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Gulkis M, Luo M, Chipman P, Mietzsch M, Söderlund-Venermo M, Bennett A, McKenna R. Structural Characterization of Human Bufavirus 1: Receptor Binding and Endosomal pH-Induced Changes. Viruses 2024; 16:1258. [PMID: 39205232 PMCID: PMC11360561 DOI: 10.3390/v16081258] [Citation(s) in RCA: 0] [Impact Index Per Article: 0] [Reference Citation Analysis] [Abstract] [Key Words] [MESH Headings] [Grants] [Track Full Text] [Download PDF] [Figures] [Journal Information] [Subscribe] [Scholar Register] [Received: 07/01/2024] [Revised: 07/30/2024] [Accepted: 08/03/2024] [Indexed: 09/04/2024] Open
Abstract
Bufaviruses (BuV) are members of the Parvoviridae of the Protoparvovirus genus. They are non-enveloped, T = 1 icosahedral ssDNA viruses isolated from patients exhibiting acute diarrhea. The lack of treatment options and a limited understanding of their disease mechanisms require studying these viruses on a molecular and structural level. In the present study, we utilize glycan arrays and cell binding assays to demonstrate that BuV1 capsid binds terminal sialic acid (SIA) glycans. Furthermore, using cryo-electron microscopy (cryo-EM), SIA is shown to bind on the 2/5-fold wall of the capsid surface. Interestingly, the capsid residues stabilizing SIA binding are conserved in all human BuVs identified to date. Additionally, biophysical assays illustrate BuV1 capsid stabilization during endo-lysosomal (pH 7.4-pH 4) trafficking and capsid destabilization at pH 3 and less, which correspond to the pH of the stomach. Hence, we determined the cryo-EM structures of BuV1 capsids at pH 7.4, 4.0, and 2.6 to 2.8 Å, 3.2 Å, and 2.7 Å, respectively. These structures reveal capsid structural rearrangements during endo-lysosomal escape and provide a potential mechanism for this process. The structural insights gained from this study will add to the general knowledge of human pathogenic parvoviruses. Furthermore, the identification of the conserved SIA receptor binding site among BuVs provides a possible targetable surface-accessible pocket for the design of small molecules to be developed as anti-virals for these viruses.
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Affiliation(s)
- Mitchell Gulkis
- Department of Biochemistry and Molecular Biology, University of Florida, Gainesville, FL 32611, USA; (M.G.); (M.L.); (P.C.); (M.M.)
| | - Mengxiao Luo
- Department of Biochemistry and Molecular Biology, University of Florida, Gainesville, FL 32611, USA; (M.G.); (M.L.); (P.C.); (M.M.)
| | - Paul Chipman
- Department of Biochemistry and Molecular Biology, University of Florida, Gainesville, FL 32611, USA; (M.G.); (M.L.); (P.C.); (M.M.)
| | - Mario Mietzsch
- Department of Biochemistry and Molecular Biology, University of Florida, Gainesville, FL 32611, USA; (M.G.); (M.L.); (P.C.); (M.M.)
| | - Maria Söderlund-Venermo
- Department of Virology, University of Helsinki, P.O. Box 21 (Haartmaninkatu 3), FIN-00014 Helsinki, Finland;
| | - Antonette Bennett
- Department of Biochemistry and Molecular Biology, University of Florida, Gainesville, FL 32611, USA; (M.G.); (M.L.); (P.C.); (M.M.)
| | - Robert McKenna
- Department of Biochemistry and Molecular Biology, University of Florida, Gainesville, FL 32611, USA; (M.G.); (M.L.); (P.C.); (M.M.)
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Weitschies W, Müller L, Grimm M, Koziolek M. Ingestible devices for studying the gastrointestinal physiology and their application in oral biopharmaceutics. Adv Drug Deliv Rev 2021; 176:113853. [PMID: 34192551 DOI: 10.1016/j.addr.2021.113853] [Citation(s) in RCA: 15] [Impact Index Per Article: 3.8] [Reference Citation Analysis] [Abstract] [Key Words] [MESH Headings] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 03/31/2021] [Revised: 06/22/2021] [Accepted: 06/23/2021] [Indexed: 12/17/2022]
Abstract
Ingestible sensor systems are unique tools for obtaining physiological data from an undisturbed gastrointestinal tract. Since their dimensions correspond to monolithic oral dosage forms, such as enteric coated tablets or hydrogel matrix tablets, they also allow insights into the physiological conditions experienced by non-disintegrating dosage forms on their way through the gastrointestinal tract. In this work, the different ingestible sensor systems which can be used for this purpose are described and their potential applications as well as difficulties and pitfalls with respect to their use are presented. It is also highlighted how the data on transit times, pH, temperature and pressure as well as the data from different animal models commonly used in drug product development such as dogs and pigs have contributed to a deeper mechanistic understanding of oral drug delivery.
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Affiliation(s)
- Werner Weitschies
- Institute of Pharmacy, Center of Drug Absorption and Transport, University of Greifswald, Greifswald, Germany.
| | - Laura Müller
- Institute of Pharmacy, Center of Drug Absorption and Transport, University of Greifswald, Greifswald, Germany
| | - Michael Grimm
- Institute of Pharmacy, Center of Drug Absorption and Transport, University of Greifswald, Greifswald, Germany
| | - Mirko Koziolek
- NCE Formulation Sciences, AbbVie Deutschland GmbH & Co. KG, Ludwigshafen, Germany
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The Coordination Chemistry of Bio-Relevant Ligands and Their Magnesium Complexes. Molecules 2020; 25:molecules25143172. [PMID: 32664540 PMCID: PMC7397051 DOI: 10.3390/molecules25143172] [Citation(s) in RCA: 14] [Impact Index Per Article: 2.8] [Reference Citation Analysis] [Abstract] [Key Words] [Track Full Text] [Download PDF] [Figures] [Journal Information] [Subscribe] [Scholar Register] [Received: 06/22/2020] [Revised: 07/07/2020] [Accepted: 07/08/2020] [Indexed: 12/15/2022] Open
Abstract
The coordination chemistry of magnesium (Mg2+) was extensively explored. More recently; magnesium; which plays a role in over 80% of metabolic functions and governs over 350 enzymatic processes; is becoming increasingly linked to chronic disease—predominantly due to magnesium deficiency (hypomagnesemia). Supplemental dietary magnesium utilizing biorelevant chelate ligands is a proven method for counteracting hypomagnesemia. However, the coordination chemistry of such bio-relevant magnesium complexes is yet to be extensively explored or elucidated. It is the aim of this review to comprehensively describe what is currently known about common bio-relevant magnesium complexes from the perspective of coordination chemistry.
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pH-dependent activation of cytokinesis modulates Escherichia coli cell size. PLoS Genet 2020; 16:e1008685. [PMID: 32203516 PMCID: PMC7117782 DOI: 10.1371/journal.pgen.1008685] [Citation(s) in RCA: 14] [Impact Index Per Article: 2.8] [Reference Citation Analysis] [Abstract] [Track Full Text] [Download PDF] [Figures] [Journal Information] [Subscribe] [Scholar Register] [Received: 09/24/2019] [Revised: 04/02/2020] [Accepted: 02/19/2020] [Indexed: 01/21/2023] Open
Abstract
Cell size is a complex trait, derived from both genetic and environmental factors. Environmental determinants of bacterial cell size identified to date primarily target assembly of cytosolic components of the cell division machinery. Whether certain environmental cues also impact cell size through changes in the assembly or activity of extracytoplasmic division proteins remains an open question. Here, we identify extracellular pH as a modulator of cell division and a significant determinant of cell size across evolutionarily distant bacterial species. In the Gram-negative model organism Escherichia coli, our data indicate environmental pH impacts the length at which cells divide by altering the ability of the terminal cell division protein FtsN to localize to the cytokinetic ring where it activates division. Acidic environments lead to enrichment of FtsN at the septum and activation of division at a reduced cell length. Alkaline pH inhibits FtsN localization and suppresses division activation. Altogether, our work reveals a previously unappreciated role for pH in bacterial cell size control. Bacteria are constantly under assault from endogenous and environmental stressors. To ensure viability and reproductive fitness, many bacteria alter their growth and replication in response to stressful conditions. Previous work from many groups has identified regulatory mechanisms linking cell division with nutrient availability and metabolic state. However, comparatively little is known about how the cell division machinery responds to physical and chemical cues in the environment. Here, we identify a fundamental property of the extracellular environment—environmental pH—as a significant contributor to bacterial cell size. Our genetic and cytological data indicate pH-dependent changes in E. coli cell size are in part due to differential localization of the cell division activator FtsN across pH environments. Increased abundance of FtsN at midcell in acidic environments promotes cell division at a reduced cell volume, while decreased abundance of FtsN at midcell in alkaline environments effectively delays cell division until a larger size is reached. Altogether, our work identifies pH as an environmental determinant of E. coli cell division and illuminates FtsN recruitment as a mediator of cell size.
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Mueller EA, Egan AJ, Breukink E, Vollmer W, Levin PA. Plasticity of Escherichia coli cell wall metabolism promotes fitness and antibiotic resistance across environmental conditions. eLife 2019; 8:40754. [PMID: 30963998 PMCID: PMC6456298 DOI: 10.7554/elife.40754] [Citation(s) in RCA: 58] [Impact Index Per Article: 9.7] [Reference Citation Analysis] [Abstract] [Key Words] [Track Full Text] [Download PDF] [Figures] [Journal Information] [Subscribe] [Scholar Register] [Received: 08/05/2018] [Accepted: 03/23/2019] [Indexed: 11/13/2022] Open
Abstract
Although the peptidoglycan cell wall is an essential structural and morphological feature of most bacterial cells, the extracytoplasmic enzymes involved in its synthesis are frequently dispensable under standard culture conditions. By modulating a single growth parameter-extracellular pH-we discovered a subset of these so-called 'redundant' enzymes in Escherichia coli are required for maximal fitness across pH environments. Among these pH specialists are the class A penicillin binding proteins PBP1a and PBP1b; defects in these enzymes attenuate growth in alkaline and acidic conditions, respectively. Genetic, biochemical, and cytological studies demonstrate that synthase activity is required for cell wall integrity across a wide pH range and influences pH-dependent changes in resistance to cell wall active antibiotics. Altogether, our findings reveal previously thought to be redundant enzymes are instead specialized for distinct environmental niches. This specialization may ensure robust growth and cell wall integrity in a wide range of conditions. Editorial note This article has been through an editorial process in which the authors decide how to respond to the issues raised during peer review. The Reviewing Editor's assessment is that all the issues have been addressed (see decision letter).
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Affiliation(s)
- Elizabeth A Mueller
- Department of Biology, Washington University in St. Louis, St. Louis, United States
| | - Alexander Jf Egan
- Centre for Bacterial Cell Biology, Institute for Cell and Molecular Biosciences, Newcastle University, Newcastle upon Tyne, United Kingdom
| | - Eefjan Breukink
- Membrane Biochemistry and Biophysics, Department of Chemistry, Faculty of Science, Utrecht University, Utrecht, Netherlands
| | - Waldemar Vollmer
- Centre for Bacterial Cell Biology, Institute for Cell and Molecular Biosciences, Newcastle University, Newcastle upon Tyne, United Kingdom
| | - Petra Anne Levin
- Department of Biology, Washington University in St. Louis, St. Louis, United States
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Jiang H, Yu W, Oscai M, Ziaie B. A Smart Capsule With a Hydrogel-Based pH-Triggered Release Switch for GI-Tract Site-Specific Drug Delivery. IEEE Trans Biomed Eng 2018; 65:2808-2813. [PMID: 29993401 DOI: 10.1109/tbme.2018.2818463] [Citation(s) in RCA: 19] [Impact Index Per Article: 2.7] [Reference Citation Analysis] [Abstract] [MESH Headings] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 11/05/2022]
Abstract
In this paper, we present a smart capsule that can release its payload after a predetermined/adjustable delay subsequent to passing from the stomach into the small intestine. The described capsule (9 mm × 22 mm) comprises a pH-sensitive hydrogel-based switch, an electronic compartment containing a capacitor charged to 2.7 V, and a drug reservoir capped by a taut fusible thread intertwined with a nichrome wire. The nichrome wire, capacitor, and pH-responsive electrical switch are connected in series. The pH transition the capsule encounters when it enters the small intestine triggers controlled swelling of the pH-responsive hydrogel, which pushes a conductive elastic membrane to close an electrical switch. This initiates a sequence of events, i.e., the discharge of the capacitor, heating the nichrome wire, breakage of the fusible thread, and release of the payload stored in the capsule reservoir through the unlatched cap. The time lag between initiation of hydrogel swelling (by the near-neutral pH of the small intestine) and payload release is controlled by the deflection of the conductive elastic membrane and the gap separating the contacts. The release time can be set to within ±5 min after one hour in the small intestine (start of the swelling) increasing to ±40 min after 4 h.
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Jain SK, Tiwari A, Jain A, Verma A, Saraf S, Panda PK, Gour G. Application Potential of Polymeric Nanoconstructs for Colon-Specific Drug Delivery. ACTA ACUST UNITED AC 2018. [DOI: 10.4018/978-1-5225-4781-5.ch002] [Citation(s) in RCA: 5] [Impact Index Per Article: 0.7] [Reference Citation Analysis] [Abstract] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 12/13/2022]
Abstract
Numerous applications of colon-specific drug delivery have been found in a wide array of diseases like irritable bowel syndrome (IBS), inflammatory bowel diseases (ulcerative colitis and Crohn's disease), colorectal cancer, and diverticulitis. Drug delivery to the colon has different anatomic and pathophysiological barriers. In recent advancements, these barriers were overcome by using biodegradable polymeric nanoconstructs, which are exhibiting minimal systemic adverse effects. Various polymeric nanoconstructs (PNCs) such as nanoparticles, micelles, and dendrimers have been exploited for effective targeting to pathological sites of colon. PNCs on oral administration not only protect the bioactive from physicochemical degradation but also prevent premature leakage in the upper parts of gastrointestinal tract. The chapter summarizes various PNCs-based approaches for colon-specific drug delivery.
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Wang YT, Mohammed SD, Farmer AD, Wang D, Zarate N, Hobson AR, Hellström PM, Semler JR, Kuo B, Rao SS, Hasler WL, Camilleri M, Scott SM. Regional gastrointestinal transit and pH studied in 215 healthy volunteers using the wireless motility capsule: influence of age, gender, study country and testing protocol. Aliment Pharmacol Ther 2015. [PMID: 26223837 DOI: 10.1111/apt.13329] [Citation(s) in RCA: 112] [Impact Index Per Article: 11.2] [Reference Citation Analysis] [Abstract] [Track Full Text] [Journal Information] [Submit a Manuscript] [Subscribe] [Scholar Register] [Indexed: 12/28/2022]
Abstract
BACKGROUND The wireless motility capsule (WMC) offers the ability to investigate luminal gastrointestinal (GI) physiology in a minimally invasive manner. AIM To investigate the effect of testing protocol, gender, age and study country on regional GI transit times and associated pH values using the WMC. METHODS Regional GI transit times and pH values were determined in 215 healthy volunteers from USA and Sweden studied using the WMC over a 6.5-year period. The effects of test protocol, gender, age and study country were examined. RESULTS For GI transit times, testing protocol was associated with differences in gastric emptying time (GET; shorter with protocol 2 (motility capsule ingested immediately after meal) vs. protocol 1 (motility capsule immediately before): median difference: 52 min, P = 0.0063) and colonic transit time (CTT; longer with protocol 2: median 140 min, P = 0.0189), but had no overall effect on whole gut transit time. Females had longer GET (by median 17 min, P = 0.0307), and also longer CTT by (104 min, P = 0.0285) and whole gut transit time by (263 min, P = 0.0077). Increasing age was associated with shorter small bowel transit time (P = 0.002), and study country also influenced small bowel and CTTs. Whole gut and CTTs showed clustering of data at values separated by 24 h, suggesting that describing these measures as continuous variables is invalid. Testing protocol, gender and study country also significantly influenced pH values. CONCLUSIONS Regional GI transit times and pH values, delineated using the wireless motility capsule (WMC), vary based on testing protocol, gender, age and country. Standardisation of testing is crucial for cross-referencing in clinical practice and future research.
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Affiliation(s)
- Y T Wang
- Neurogastroenterology Group (GI Physiology Unit), Blizard Institute of Cell and Molecular Science, Queen Mary University, London, UK
| | - S D Mohammed
- Neurogastroenterology Group (GI Physiology Unit), Blizard Institute of Cell and Molecular Science, Queen Mary University, London, UK
| | - A D Farmer
- Neurogastroenterology Group (GI Physiology Unit), Blizard Institute of Cell and Molecular Science, Queen Mary University, London, UK.,University Hospitals of North Midlands, Royal Stoke University Hospital, Stoke on Trent, UK
| | - D Wang
- Biostatistics Unit, Department of Clinical Sciences, Liverpool School of Tropical Medicine, Liverpool, UK
| | - N Zarate
- Department of Gastroenterology, University College London Hospital, London, UK
| | | | - P M Hellström
- Department of Medical Sciences, Uppsala University Hospital, Uppsala, Sweden
| | | | - B Kuo
- Gastroenterology Unit, Massachusetts General Hospital, Harvard Medical School, Boston, MA, USA
| | - S S Rao
- Section of Gastroenterology and Hepatology, Georgia Health Sciences University, Medical College of Georgia, Augusta, GA, USA
| | - W L Hasler
- Division of Gastroenterology, University of Michigan Health System, Ann Arbor, MI, USA
| | - M Camilleri
- Clinical Enteric Neuroscience Translational and Epidemiological Research (CENTER), Division of Gastroenterology and Hepatology, Mayo Clinic, Rochester, MN, USA
| | - S M Scott
- Neurogastroenterology Group (GI Physiology Unit), Blizard Institute of Cell and Molecular Science, Queen Mary University, London, UK
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Ringel-Kulka T, Choi CH, Temas D, Kim A, Maier DM, Scott K, Galanko JA, Ringel Y. Altered Colonic Bacterial Fermentation as a Potential Pathophysiological Factor in Irritable Bowel Syndrome. Am J Gastroenterol 2015; 110:1339-46. [PMID: 26303129 PMCID: PMC4983766 DOI: 10.1038/ajg.2015.220] [Citation(s) in RCA: 102] [Impact Index Per Article: 10.2] [Reference Citation Analysis] [Abstract] [Key Words] [MESH Headings] [Grants] [Track Full Text] [Journal Information] [Submit a Manuscript] [Subscribe] [Scholar Register] [Received: 12/30/2014] [Accepted: 06/20/2015] [Indexed: 12/11/2022]
Abstract
OBJECTIVES Dysbiosis leading to abnormal intestinal fermentation has been suggested as a possible etiological mechanism in irritable bowel syndrome (IBS). We aimed to investigate the location and magnitude of altered intestinal bacterial fermentation in IBS and its clinical subtypes. METHODS IBS patients who satisfied the Rome III criteria (114) and 33 healthy controls (HC) were investigated. Intestinal fermentation was assessed using two surrogate measures: intestinal intraluminal pH and fecal short-chain fatty acids (SCFAs). Intraluminal pH and intestinal transit times were measured in the small and large bowel using a wireless motility capsule (SmartPill) in 47 IBS and 10 HC. Fecal SCFAs including acetate, propionate, butyrate, and lactate were analyzed by capillary gas chromatography in all enrolled subjects. Correlations between intestinal pH, fecal SCFAs, intestinal transit time, and IBS symptom scores were analyzed. RESULTS Colonic intraluminal pH levels were significantly lower in IBS patients compared with HC (total colonic pH, 6.8 for IBS vs. 7.3 for HC, P=0.042). There were no differences in total and segmental pH levels in the small bowel between IBS patients and HC (6.8 vs. 6.8, P=not significant). The intraluminal colonic pH differences were consistent in all IBS subtypes. Total SCFA level was significantly lower in C-IBS patients than in D-IBS and M-IBS patients and HC. The total SCFA level in all IBS subjects was similar with that of HC. Colonic pH levels correlated positively with colon transit time (CTT) and IBS symptoms severity. Total fecal SCFAs levels correlated negatively with CTT and positively with stool frequency. CONCLUSIONS Colonic intraluminal pH is decreased, suggesting higher colonic fermentation, in IBS patients compared with HC. Fecal SCFAs are not a sensitive marker to estimate intraluminal bacterial fermentation.
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Affiliation(s)
- Tamar Ringel-Kulka
- Gillings School of Global Public Health, University of North Carolina, Chapel Hill, NC, USA
| | - Chang Hwan Choi
- Division of Gastroenterology and Hepatology, Center for Gastrointestinal Biology and Disease, University of North Carolina at Chapel Hill, Chapel Hill, North Carolina, USA
- Department of Internal Medicine, Chung-Ang University College of Medicine, Seoul, Republic of Korea
| | - Daniel Temas
- Division of Gastroenterology and Hepatology, Center for Gastrointestinal Biology and Disease, University of North Carolina at Chapel Hill, Chapel Hill, North Carolina, USA
| | - Ari Kim
- Gillings School of Global Public Health, University of North Carolina, Chapel Hill, NC, USA
- Department of Obstetrics and Gynecology, Institute of Wonkwang Medical Science, Wonkwang University College of Medicine, Iksan, Republic of Korea
| | - Daniele M Maier
- Division of Gastroenterology and Hepatology, Center for Gastrointestinal Biology and Disease, University of North Carolina at Chapel Hill, Chapel Hill, North Carolina, USA
| | - Karen Scott
- Rowett Institute of Nutrition and Health, University of Aberdeen, Aberdeen, United Kingdom
| | - Joseph A Galanko
- Division of Gastroenterology and Hepatology, Center for Gastrointestinal Biology and Disease, University of North Carolina at Chapel Hill, Chapel Hill, North Carolina, USA
| | - Yehuda Ringel
- Division of Gastroenterology and Hepatology, Center for Gastrointestinal Biology and Disease, University of North Carolina at Chapel Hill, Chapel Hill, North Carolina, USA
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Gastrointestinal pH and Transit Time Profiling in Healthy Volunteers Using the IntelliCap System Confirms Ileo-Colonic Release of ColoPulse Tablets. PLoS One 2015; 10:e0129076. [PMID: 26177019 PMCID: PMC4503763 DOI: 10.1371/journal.pone.0129076] [Citation(s) in RCA: 83] [Impact Index Per Article: 8.3] [Reference Citation Analysis] [Abstract] [Track Full Text] [Download PDF] [Figures] [Journal Information] [Subscribe] [Scholar Register] [Received: 12/30/2014] [Accepted: 05/03/2015] [Indexed: 01/01/2023] Open
Abstract
INTRODUCTION ColoPulse tablets are an innovative development in the field of oral dosage forms characterized by a distal ileum and colon-specific release. Previous studies in humans showed release in the ileo-colonic region, but the relationship between gastrointestinal pH and release was not experimentally proven in vivo. This information will complete the in vivo release-profile of ColoPulse tablets. MATERIALS AND METHODS Release from ColoPulse tablets was studied in 16 healthy volunteers using the dual label isotope strategy. To determine gastrointestinal pH profiles and transit times the IntelliCap system was used. A ColoPulse tablet containing 13C-urea and an uncoated, immediate release tablet containing 15N2-urea were taken simultaneously followed by a standardized breakfast after three hours. Five minutes after intake of the tablets the IntelliCap capsule was swallowed and pH was measured until excretion in the feces. Breath and urine samples were collected for isotope analysis. RESULTS Full analysis could be performed in 12 subjects. Median bioavailability of 13C -urea was 82% (95% CI 74-94%, range 61-114%). The median lag time (5% release of 13C) was 5:42 h (95% CI 5:18-6:18 h, range 2:36-6:36 h,) There was no statistically significant difference between lag time based on isotope signal and colon arrival time (CAT) based on pH (median 5:42 vs 5:31 h p = 0.903). In all subjects an intestinal pH value of 7.0 was reached before release of 13C from the ColoPulse tablet occurred. DISCUSSION AND CONCLUSIONS From the combined data from the IntelliCap system and the 13C -isotope signal it can be concluded that release from a ColoPulse tablet in vivo is not related to transit times but occurs in the ileo-colonic region after pH 7.0 is reached. This supports our earlier findings and confirms that the ColoPulse system is a promising delivery system for targeting the distal ileum and colon. TRIAL REGISTRATION ISRCTN Registry 18301880.
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Assessment of Tandem Measurements of pH and Total Gut Transit Time in Healthy Volunteers. Clin Transl Gastroenterol 2015; 6:e100. [PMID: 26158610 PMCID: PMC4816255 DOI: 10.1038/ctg.2015.22] [Citation(s) in RCA: 23] [Impact Index Per Article: 2.3] [Reference Citation Analysis] [Abstract] [Track Full Text] [Download PDF] [Figures] [Journal Information] [Submit a Manuscript] [Subscribe] [Scholar Register] [Received: 10/29/2014] [Accepted: 03/13/2015] [Indexed: 01/20/2023] Open
Abstract
OBJECTIVES The variation of luminal pH and transit time in an individual is unknown, yet is necessary to interpret single measurements. This study aimed to assess the intrasubject variability of gut pH and transit time in healthy volunteers using SmartPill devices (Covidien, Minneapolis, MN). METHODS Each subject (n=10) ingested two SmartPill devices separated by 24 h. Mean pH values were calculated for 30 min after gastric emptying (AGE), before the ileocecal (BIC) valve, after the ileocecal (AIC) valve, and before body exit (BBE). Intrasubject variability was determined by comparing mean values from both ingestions for an individual subject using standard deviations, 95% limits of agreement, and Bland-Altman plots. RESULTS Tandem device ingestion occurred without complication. The median (full range) intrasubject standard deviations for pH were 0.02 (0.0002-0.2048) for AGE, 0.06 (0.0002-0.3445) for BIC, 0.14 (0.0018-0.3042) for AIC, and 0.08 (0.0098-0.5202) for BBE. There was a significant change in pH for AIC (mean difference: -0.45±0.31, P=0.0015) observed across all subjects. The mean coefficients of variation for transit time were 12.0±7.4% and 25.8±15.8% for small and large bowels, respectively (P=0.01). CONCLUSIONS This study demonstrates the safety and feasibility of tandem gut transit and pH assessments using the SmartPill device. In healthy individuals and over 24 h, the gut pH profile does not markedly fluctuate in a given region with more variation seen in the colon compared with the small bowel, which has important implications for future physiology and drug delivery studies.
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Ma Y, Fuchs AV, Boase NRB, Rolfe BE, Coombes AGA, Thurecht KJ. The in vivo fate of nanoparticles and nanoparticle-loaded microcapsules after oral administration in mice: Evaluation of their potential for colon-specific delivery. Eur J Pharm Biopharm 2015; 94:393-403. [PMID: 26117186 DOI: 10.1016/j.ejpb.2015.06.014] [Citation(s) in RCA: 38] [Impact Index Per Article: 3.8] [Reference Citation Analysis] [Abstract] [Key Words] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 03/19/2015] [Revised: 06/11/2015] [Accepted: 06/12/2015] [Indexed: 01/08/2023]
Abstract
Anti-cancer drug loaded-nanoparticles (NPs) or encapsulation of NPs in colon-targeted delivery systems shows potential for increasing the local drug concentration in the colon leading to improved treatment of colorectal cancer. To investigate the potential of the NP-based strategies for colon-specific delivery, two formulations, free Eudragit® NPs and enteric-coated NP-loaded chitosan-hypromellose microcapsules (MCs) were fluorescently-labelled and their tissue distribution in mice after oral administration was monitored by multispectral small animal imaging. The free NPs showed a shorter transit time throughout the mouse digestive tract than the MCs, with extensive excretion of NPs in faeces at 5h. Conversely, the MCs showed complete NP release in the lower region of the mouse small intestine at 8h post-administration. Overall, the encapsulation of NPs in MCs resulted in a higher colonic NP intensity from 8h to 24h post-administration compared to the free NPs, due to a NP 'guarding' effect of MCs during their transit along mouse gastrointestinal tract which decreased NP excretion in faeces. These imaging data revealed that this widely-utilised colon-targeting MC formulation lacked site-precision for releasing its NP load in the colon, but the increased residence time of the NPs in the lower gastrointestinal tract suggests that it is still useful for localised release of chemotherapeutics, compared to NP administration alone. In addition, both formulations resided in the stomach of mice at considerable concentrations over 24h. Thus, adhesion of NP- or MC-based oral delivery systems to gastric mucosa may be problematic for colon-specific delivery of the cargo to the colon and should be carefully investigated for a full evaluation of particulate delivery systems.
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Affiliation(s)
- Yiming Ma
- Australian Institute of Bioengineering and Nanotechnology, The University of Queensland, Brisbane, Australia; Centre for Advanced Imaging, The University of Queensland, Brisbane, Australia
| | - Adrian V Fuchs
- Australian Institute of Bioengineering and Nanotechnology, The University of Queensland, Brisbane, Australia; Centre for Advanced Imaging, The University of Queensland, Brisbane, Australia
| | - Nathan R B Boase
- Australian Institute of Bioengineering and Nanotechnology, The University of Queensland, Brisbane, Australia; Centre for Advanced Imaging, The University of Queensland, Brisbane, Australia
| | - Barbara E Rolfe
- Australian Institute of Bioengineering and Nanotechnology, The University of Queensland, Brisbane, Australia
| | - Allan G A Coombes
- The International Medical University, School of Pharmacy, No. 126 Jalan Jalil Perkasa 19, Bukit Jalil, 57000 Kuala Lumpur, Malaysia
| | - Kristofer J Thurecht
- Australian Institute of Bioengineering and Nanotechnology, The University of Queensland, Brisbane, Australia; Centre for Advanced Imaging, The University of Queensland, Brisbane, Australia; ARC Centre of Excellence in Convergent BioNano Science and Technology, Australia.
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Rani GU, Dey KP, Bharti S, Mishra S. Controlled drug release of 5-amino salicylic acid by poly(2-hydroxyethylmethacrylate) grafted agar. Front Chem Sci Eng 2014. [DOI: 10.1007/s11705-014-1452-8] [Citation(s) in RCA: 20] [Impact Index Per Article: 1.8] [Reference Citation Analysis] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 11/25/2022]
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14
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Bioavailability of AREDS1 micronutrients from softgel capsules and tablets: a pilot study. Mol Vis 2014; 20:1228-42. [PMID: 25352732 PMCID: PMC4164907] [Citation(s) in RCA: 0] [Impact Index Per Article: 0] [Reference Citation Analysis] [Abstract] [Download PDF] [Figures] [Journal Information] [Subscribe] [Scholar Register] [Received: 02/12/2014] [Accepted: 09/09/2014] [Indexed: 11/01/2022] Open
Abstract
PURPOSE The benefits of antioxidant micronutrients in slowing progression to advanced stages of age-related macular degeneration (AMD) was supported by the 4/day tablet form investigated in the Age-related Eye Disease Study 1 (AREDS1) and the 2/day softgel form in the Age-related Eye Disease Study 2 (AREDS2). However, the choices of excipient, dosage form, and ingredient chemistry as well as the patient physiologies and pathologies can influence bioavailability and efficacy. The objective of the study was to explore the influence of dosage form on the bioavailability of the five primary AREDS1 and Tier-2 AREDS2 micronutrients: the metals zinc and copper, β-carotene, and vitamins E and C. The intent was to establish by chemical analysis the relative bioavailabilities of these five micronutrients in plasma, or serum for the metals, as well as to identify any opportunities for improvements. METHODS A total of 15 healthy men (5) and women (10) were recruited for a controlled, randomized, three-arm, crossover trial of the AREDS1 micronutrients. The study investigated responses in bioabsorption to a single dose of either four tablets or two softgels at the full dose level, or one softgel at the half-dose level. The bioavailability of each micronutrient was based on the pharmacokinetic profiles established through 15 samplings for each ingredient/dosage form in plasma/serum over the course of one week. RESULTS Bioavailability was estimated using model-independent and model-dependent procedures. A statistical advantage of the dosage form was observed in only two cases from the exaggerated effects using the half-dose softgel and for the tablet dosage form for β-carotene and vitamin E. An unanticipated complexity was suggested by the bimodal absorption of zinc. For these micronutrients, no disadvantage (though potential advantage) was inferred for the water-soluble components presented in a softgel formulation. Increased fractional absorption was observed for the smaller dose (one capsule versus two), but it was not sufficient to reach the level achieved by the full dose of either four tablets or two softgels. A model-dependent analysis permitted an estimation of the percentage of micronutrients absorbed, with zinc, the single most important ingredient, absorbed at about a 10% level. CONCLUSIONS The results suggest modestly contradictory requirements in the dosage form for water-soluble and lipid-soluble ingredients, as based on a goal of improved bioavailability. Comparative consistency in bioavailability was observed across dosage forms, and most nutrients between AREDS1 and AREDS2 (full dose) formulations relative to the significant variations observed within this controlled population. The results emphasize the importance of defining the requisite bioavailability of each micronutrient and the influence of the dosage form that provides it. With the recognition of global and population-specific micronutrient deficiencies, notably in the elderly populations afflicted with AMD and their significant metabolic and health consequences, establishing efficient means of supplementation are of continuing epidemiologic interest.
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Dimitrijevic J, Krapf L, Wolter C, Schmidtke C, Merkl JP, Jochum T, Kornowski A, Schüth A, Gebert A, Hüttmann G, Vossmeyer T, Weller H. CdSe/CdS-quantum rods: fluorescent probes for in vivo two-photon laser scanning microscopy. NANOSCALE 2014; 6:10413-10422. [PMID: 25080095 DOI: 10.1039/c4nr02702g] [Citation(s) in RCA: 18] [Impact Index Per Article: 1.6] [Reference Citation Analysis] [Abstract] [MESH Headings] [Track Full Text] [Subscribe] [Scholar Register] [Indexed: 06/03/2023]
Abstract
CdSe/CdS-Quantum-dots-quantum-rods (QDQRs) with an aspect ratio of ∼ 6 are prepared via the seeded growth method, encapsulated within a shell of crosslinked poly(isoprene)-block-poly(ethylene glycol) (PI-b-PEG) diblock copolymer, and transferred from the organic phase into aqueous media. Their photoluminescence quantum yield (PLQY) of 78% is not compromised by the phase transfer. Within a period of two months the PLQY of QDQRs in aqueous solution at neutral pH decreases only slightly (to ∼ 65%). The two-photon (TP) action cross sections of QDQRs (∼ 10(5) GM) are two orders of magnitude higher than those of CdSe/CdS/ZnS-core/shell/shell quantum dots (QDs, ∼ 10(3) GM) with comparable diameter (∼ 5 nm). After applying PI-b-PEG encapsulated QDQRs onto the small intestinal mucosa of mice in vivo, their strong red fluorescence can easily be observed by two-photon laser scanning microscopy (TPLSM) and clearly distinguished from autofluorescent background. Our results demonstrate that PI-b-PEG encapsulated CdSe/CdS-QDQRs are excellent probes for studying the uptake and fate of nanoparticles by two-photon imaging techniques in vivo.
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Affiliation(s)
- Jelena Dimitrijevic
- Institute of Physical Chemistry, University of Hamburg, Grindelallee 117, 20146 Hamburg, Germany.
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Nokhodchi A, Asare-Addo K. Drug release from matrix tablets: physiological parameters and the effect of food. Expert Opin Drug Deliv 2014; 11:1401-18. [DOI: 10.1517/17425247.2014.924498] [Citation(s) in RCA: 15] [Impact Index Per Article: 1.4] [Reference Citation Analysis] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 11/05/2022]
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Farmer AD, Mohammed SD, Dukes GE, Scott SM, Hobson AR. Caecal pH is a biomarker of excessive colonic fermentation. World J Gastroenterol 2014; 20:5000-5007. [PMID: 24803812 PMCID: PMC4009533 DOI: 10.3748/wjg.v20.i17.5000] [Citation(s) in RCA: 38] [Impact Index Per Article: 3.5] [Reference Citation Analysis] [Abstract] [Key Words] [MESH Headings] [Track Full Text] [Download PDF] [Journal Information] [Submit a Manuscript] [Subscribe] [Scholar Register] [Received: 09/06/2013] [Revised: 10/22/2013] [Accepted: 01/05/2014] [Indexed: 02/07/2023] Open
Abstract
AIM: To ascertain whether caecal pH is different in patients with irritable bowel syndrome (IBS), whose primary symptoms are bloating and distension, to healthy controls.
METHODS: Motility and pH data were reviewed from 16 patients with Rome III defined IBS and 16 healthy controls, who had undergone a wireless motility capsule (WMC) study using a standardized protocol. Motility measures were anchored around known anatomical landmarks as identified by compartmental pH changes. Sixty-minute epochs were used to quantify antral, duodenal, ileal, caecal and distal colonic contractility. The maximum and minimum pH was measured either side of the ileo-caecal junction.
RESULTS: No differences were seen in motility parameters, compartmental transit times or maximal ileal pH between the two groups. Caecal pH was significantly lower in patients compared to controls (5.12 ± 0.05 vs 6.16 ± 0.15, P < 0.0001). The ileal:caecal Δchange was greater in patients than controls (-2.63 ± 0.08 vs -1.42 ± 0.11, P < 0.0001). There was a significant correlation between caecal pH and right colonic contractility (r = 0.54, P = 0.002).
CONCLUSION: Patients with bloating and distension have a lower caecal pH compared to controls. The measurement of caecal pH using the WMC provides a quantifiable biomarker of fermentation potentially identifying those patients that may preferentially benefit from antibiotic or dietary interventions.
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Physiological responses to short-term fasting among herbivorous, omnivorous, and carnivorous fishes. J Comp Physiol B 2014; 184:497-512. [DOI: 10.1007/s00360-014-0813-4] [Citation(s) in RCA: 33] [Impact Index Per Article: 3.0] [Reference Citation Analysis] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 10/13/2013] [Revised: 01/29/2014] [Accepted: 02/06/2014] [Indexed: 10/25/2022]
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Ma Y, Coombes AGA. Designing colon-specific delivery systems for anticancer drug-loaded nanoparticles: An evaluation of alginate carriers. J Biomed Mater Res A 2013; 102:3167-76. [DOI: 10.1002/jbm.a.34988] [Citation(s) in RCA: 14] [Impact Index Per Article: 1.2] [Reference Citation Analysis] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 07/15/2013] [Revised: 09/23/2013] [Accepted: 10/02/2013] [Indexed: 01/30/2023]
Affiliation(s)
- Yiming Ma
- Pharmacy Australia Centre of Excellence; The University of Queensland; Woolloongabba Queensland 4102 Australia
| | - Allan G. A. Coombes
- Pharmacy Australia Centre of Excellence; The University of Queensland; Woolloongabba Queensland 4102 Australia
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Cummins J, Casey PG, Joyce SA, Gahan CGM. A mariner transposon-based signature-tagged mutagenesis system for the analysis of oral infection by Listeria monocytogenes. PLoS One 2013; 8:e75437. [PMID: 24069416 PMCID: PMC3771922 DOI: 10.1371/journal.pone.0075437] [Citation(s) in RCA: 13] [Impact Index Per Article: 1.1] [Reference Citation Analysis] [Abstract] [MESH Headings] [Track Full Text] [Download PDF] [Figures] [Journal Information] [Subscribe] [Scholar Register] [Received: 03/13/2013] [Accepted: 08/14/2013] [Indexed: 11/18/2022] Open
Abstract
Listeria monocytogenes is a Gram-positive foodborne pathogen and the causative agent of listerosis a disease that manifests predominately as meningitis in the non-pregnant individual or infection of the fetus and spontaneous abortion in pregnant women. Common-source outbreaks of foodborne listeriosis are associated with significant morbidity and mortality. However, relatively little is known concerning the mechanisms that govern infection via the oral route. In order to aid functional genetic analysis of the gastrointestinal phase of infection we designed a novel signature-tagged mutagenesis (STM) system based upon the invasive L. monocytogenes 4b serotype H7858 strain. To overcome the limitations of gastrointestinal infection by L. monocytogenes in the mouse model we created a H7858 strain that is genetically optimised for oral infection in mice. Furthermore our STM system was based upon a mariner transposon to favour numerous and random transposition events throughout the L. monocytogenes genome. Use of the STM bank to investigate oral infection by L. monocytogenes identified 21 insertion mutants that demonstrated significantly reduced potential for infection in our model. The sites of transposon insertion included lmOh7858_0671 (encoding an internalin homologous to Lmo0610), lmOh7858_0898 (encoding a putative surface-expressed LPXTG protein homologous to Lmo0842), lmOh7858_2579 (encoding the HupDGC hemin transport system) and lmOh7858_0399 (encoding a putative fructose specific phosphotransferase system). We propose that this represents an optimised STM system for functional genetic analysis of foodborne/oral infection by L. monocytogenes.
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Affiliation(s)
- Joanne Cummins
- Department of Microbiology, University College Cork, Cork, Ireland
| | - Pat G. Casey
- Department of Microbiology, University College Cork, Cork, Ireland
- Alimentary Pharmabiotic Centre, University College Cork, Cork, Ireland
| | - Susan A. Joyce
- Department of Microbiology, University College Cork, Cork, Ireland
- Alimentary Pharmabiotic Centre, University College Cork, Cork, Ireland
| | - Cormac G. M. Gahan
- Department of Microbiology, University College Cork, Cork, Ireland
- Alimentary Pharmabiotic Centre, University College Cork, Cork, Ireland
- School of Pharmacy, University College Cork, Cork, Ireland
- * E-mail:
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Modified tamarind kernel polysaccharide: A novel matrix for control release of aspirin. Int J Biol Macromol 2013; 58:296-300. [DOI: 10.1016/j.ijbiomac.2013.04.002] [Citation(s) in RCA: 23] [Impact Index Per Article: 1.9] [Reference Citation Analysis] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 01/18/2013] [Revised: 03/13/2013] [Accepted: 04/07/2013] [Indexed: 11/18/2022]
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Krishnaiah YSR, Khan MA. Strategies of targeting oral drug delivery systems to the colon and their potential use for the treatment of colorectal cancer. Pharm Dev Technol 2012; 17:521-40. [PMID: 22681390 DOI: 10.3109/10837450.2012.696268] [Citation(s) in RCA: 33] [Impact Index Per Article: 2.5] [Reference Citation Analysis] [Abstract] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 01/19/2023]
Abstract
Colorectal cancer (CRC) is the third most common cause of cancer-related death in both men and women. Often, surgical intervention remains the choice in treating CRC. Traditional dosage forms used for treating CRC deliver drug to wanted as well as unwanted sites of drug action resulting in several adverse side effects. Targeted oral drug delivery systems are being investigated to target and deliver chemotherapeutic and chemopreventive agents directly to colon and rectum. Site-specific delivery of a drug to colon increases its concentration at the target site, and thus requires a lower dose with reduced incidence of side effects. The major obstacle to be overcome for successful targeting of drug to colon through oral route is that drug absorption/degradation must be avoided in stomach and small intestine before the dosage form reaches colon. The review includes discussion of physiological factors that must be considered when targeting drugs directly to colorectal region, an outline on drugs used for treatment and prevention of CRC, and a brief description of various types of colon-targeted oral drug delivery systems. The focus is on the assessment of various formulation approaches being investigated for oral colon-specific delivery of drugs used in the treatment and prevention of CRC.
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Affiliation(s)
- Yellela S R Krishnaiah
- Division of Product Quality Research, Office of Testing and Research, Office of Pharmaceutical Science, Center for Drug Evaluation and Research, Food and Drug Administration, Silver Springs, MD 20993, USA.
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Gastrointestinal pH profile in subjects with irritable bowel syndrome. Ann Gastroenterol 2012; 25:333-337. [PMID: 24714241 PMCID: PMC3959422] [Citation(s) in RCA: 0] [Impact Index Per Article: 0] [Reference Citation Analysis] [Abstract] [Key Words] [Download PDF] [Figures] [Journal Information] [Submit a Manuscript] [Subscribe] [Scholar Register] [Received: 05/23/2012] [Accepted: 07/02/2012] [Indexed: 11/24/2022] Open
Abstract
AIM To investigate the small bowel pH profile and small intestine transit time (SITT) in healthy controls and patients with irritable bowel syndrome (IBS). METHODS Nine IBS patients (3 males, mean age 35 yr) and 10 healthy subjects (6 males, mean age 33 yr) were studied. Intestinal pH profile and SITT were assessed by a wireless motility pH and pressure capsule (Smart Pill). Mean pH values were measured in the small intestine (SI) and compared both within and between groups. Data presented as mean or median, ANOVA, P <0.05 for significance. RESULTS We found the pH for the first (Q1), second (Q2), third (Q3), and fourth quartile (Q4) of the SI in healthy versus IBS patients was 5.608 ± 0.491 vs. 5.667 ± 0.297, 6.200 ± 0.328 vs. 6.168 ± 0.288, 6.679 ± 0.316 vs. 6.741 ± 0.322, and 6.884 ± 0.200 vs. 6.899 ± 0.303, respectively. We found no significant group difference in pH per quartile (P=0.7979). The proximal SI was significantly more acidic, compared to distal segments, in both healthy subjects and IBS patients (P<0.0001). We found no significant difference in the measured SITT between IBS and control groups with a mean SITT of 218.56 ± 59.60 min and 199.20 ± 82.31 min, respectively (P=0.55). CONCLUSION This study shows the presence of a gradient of pH along the SI, in both IBS and healthy subjects, the distal being less acidic. These finding may be of importance in small bowel homeostasis.
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Zarate N, Mohammed SD, O'Shaughnessy E, Newell M, Yazaki E, Williams NS, Lunniss PJ, Semler JR, Scott SM. Accurate localization of a fall in pH within the ileocecal region: validation using a dual-scintigraphic technique. Am J Physiol Gastrointest Liver Physiol 2010; 299:G1276-86. [PMID: 20847301 DOI: 10.1152/ajpgi.00127.2010] [Citation(s) in RCA: 61] [Impact Index Per Article: 4.1] [Reference Citation Analysis] [Abstract] [Track Full Text] [Journal Information] [Submit a Manuscript] [Subscribe] [Scholar Register] [Indexed: 01/31/2023]
Abstract
Stereotypical changes in pH occur along the gastrointestinal (GI) tract. Classically, there is an abrupt increase in pH on exit from the stomach, followed later by a sharp fall in pH, attributed to passage through the ileocecal region. However, the precise location of this latter pH change has never been conclusively substantiated. We aimed to determine the site of fall in pH using a dual-scintigraphic technique. On day 1, 13 healthy subjects underwent nasal intubation with a 3-m-long catheter, which was allowed to progress to the distal ileum. On day 2, subjects ingested a pH-sensitive wireless motility capsule labeled with 4 MBq (51)Chromium [EDTA]. The course of this, as it travelled through the GI tract, was assessed with a single-headed γ-camera using static and dynamic scans. Capsule progression was plotted relative to a background of 4 MBq ¹¹¹Indium [diethylenetriamine penta-acetic acid] administered through the catheter. Intraluminal pH, as recorded by the capsule, was monitored continuously, and position of the capsule relative to pH was established. A sharp fall in pH was recorded in all subjects; position of the capsule relative to this was accurately determined anatomically in 9/13 subjects. In these nine subjects, a pH drop of 1.5 ± 0.2 U, from 7.6 ± 0.05 to 6.1 ± 0.1 occurred a median of 7.5 min (1-16) after passage through the ileocecal valve; location was either in the cecum (n = 5), ascending colon (n = 2), or coincident with a move from the cecum to ascending colon (n = 2). This study provides conclusive evidence that the fall in pH seen within the ileocolonic region actually occurs in the proximal colon. This phenomenon can be used as a biomarker of transition between the small and large bowel and validates assessment of regional GI motility using capsule technology that incorporates pH measurement.
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Investigation of the mechanisms by which Listeria monocytogenes grows in porcine gallbladder bile. Infect Immun 2010; 79:369-79. [PMID: 20937762 DOI: 10.1128/iai.00330-10] [Citation(s) in RCA: 51] [Impact Index Per Article: 3.4] [Reference Citation Analysis] [Abstract] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 01/06/2023] Open
Abstract
The food-borne pathogen Listeria monocytogenes is known to colonize the lumen of the gallbladder in infected mice and to grow rapidly in this environment (J. Hardy et al., Science 303:851-853, 2004). However, relatively little is known about the mechanisms utilized by the pathogen to survive and grow in this location. We utilized gallbladder bile (GB bile) isolated directly from porcine gallbladders as an ex vivo model of gallbladder growth. We demonstrate that GB bile is generally nontoxic for bacteria and can readily support growth of a variety of bacterial species including L. monocytogenes, Lactococcus lactis, Salmonella enterica serovar Typhimurium, and Escherichia coli. Significantly, L. monocytogenes grew at the same rate as the nonpathogenic species Listeria innocua, indicating that the pathogen does not possess specialized mechanisms that enable growth in this environment. However, when we reduced the pH of GB bile to pH 5.5 in order to mimic the release of bile within the small intestine, the toxicity of GB bile increased significantly and specific resistance mechanisms (Sigma B, BSH, and BilE) were essential for survival of the pathogen under these conditions. In order to identify genetic loci that are necessary for growth of L. monocytogenes in the gallbladder, a mariner transposon bank was created and screened for mutants unable to replicate in GB bile. This led to the identification of mutants in six loci, including genes encoding enzymes involved in purine metabolism, amino acid biosynthesis, and biotin uptake. Although GB bile does not represent a significant impediment to bacterial growth, specific metabolic processes are required by L. monocytogenes in order to grow in this environment.
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Mudie DM, Amidon GL, Amidon GE. Physiological parameters for oral delivery and in vitro testing. Mol Pharm 2010; 7:1388-405. [PMID: 20822152 DOI: 10.1021/mp100149j] [Citation(s) in RCA: 319] [Impact Index Per Article: 21.3] [Reference Citation Analysis] [Abstract] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 12/19/2022]
Abstract
Pharmaceutical solid oral dosage forms must undergo dissolution in the intestinal fluids of the gastrointestinal tract before they can be absorbed and reach the systemic circulation. Therefore, dissolution is a critical part of the drug-delivery process. The rate and extent of drug dissolution and absorption depend on the characteristics of the active ingredient as well as properties of the dosage form. Just as importantly, characteristics of the physiological environment such as buffer species, pH, bile salts, gastric emptying rate, intestinal motility, and hydrodynamics can significantly impact dissolution and absorption. While significant progress has been made since 1970 when the first compendial dissolution test was introduced (USP apparatus 1), current dissolution testing does not take full advantage of the extensive physiologic information that is available. For quality control purposes, where the question is one of lot-to-lot consistency in performance, using nonphysiologic test conditions that match drug and dosage form properties with practical dissolution media and apparatus may be appropriate. However, where in vitro-in vivo correlations are desired, it is logical to consider and utilize knowledge of the in vivo condition. This publication critically reviews the literature that is relevant to oral human drug delivery. Physiologically relevant information must serve as a basis for the design of dissolution test methods and systems that are more representative of the human condition. As in vitro methods advance in their physiological relevance, better in vitro-in vivo correlations will be possible. This will, in turn, lead to in vitro systems that can be utilized to more effectively design dosage forms that have improved and more consistent oral bioperformance.
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Affiliation(s)
- Deanna M Mudie
- College of Pharmacy, University of Michigan, Ann Arbor, MI 48109-1065, USA
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Camilleri M, Thorne NK, Ringel Y, Hasler WL, Kuo B, Esfandyari T, Gupta A, Scott SM, McCallum RW, Parkman HP, Soffer E, Wilding GE, Semler JR, Rao SS. Wireless pH-motility capsule for colonic transit: prospective comparison with radiopaque markers in chronic constipation. Neurogastroenterol Motil 2010; 22:874-82, e233. [PMID: 20465593 PMCID: PMC2911492 DOI: 10.1111/j.1365-2982.2010.01517.x] [Citation(s) in RCA: 137] [Impact Index Per Article: 9.1] [Reference Citation Analysis] [Abstract] [Key Words] [Track Full Text] [Journal Information] [Submit a Manuscript] [Subscribe] [Scholar Register] [Indexed: 12/19/2022]
Abstract
BACKGROUND Colon transit (CT) measurements are used in the management of significant constipation. The radiopaque marker (ROM) method provides limited information. METHODS We proposed to validate wireless motility capsule (WMC), that measures pH, pressure and temperature, to ROM measurement of CT in patients with symptomatic constipation evaluated at multiple centers. Of 208 patients recruited, 158 eligible patients underwent simultaneous measurement of colonic transit time (CTT) using ROM (Metcalf method, cut off for delay >67 h), and WMC (cutoff for delay >59 h). The study was designed to demonstrate substantial equivalence, defined as diagnostic agreement >65% for patients who had normal or delayed ROM transit. KEY RESULTS Fifty-nine of 157 patients had delayed ROM CT. Transit results by the two methods differed: ROM median 55.0 h [IQR 31.0-85.0] and WMC (43.5 h [21.7-70.3], P < 0.001. The positive percent agreement between WMC and ROM for delayed transit was approximately 80%; positive agreement in 47 by WMC/59 by ROM or 0.796 (95% CI = 0.67-0.98); agreement vs null hypothesis (65%) P = 0.01. The negative percent agreement (normal transit) was approximately 91%: 89 by WMC/98 by ROM or 0.908 (95% CI = 0.83-0.96); agreement vs null hypothesis (65%), P = 0.00001. Overall device agreement was 87%. There were significant correlations (P < 0.001) between ROM and WMC transit (CTT [r = 0.707] and between ROM and combined small and large bowel transit [r = 0.704]). There were no significant adverse events. CONCLUSIONS & INFERENCES The 87% overall agreement (positive and negative) validates WMC relative to ROM in differentiating slow vs normal CT in a multicenter clinical study of constipation.
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Affiliation(s)
| | - Nyree K. Thorne
- Wake Forest University Medical Center, Winston Salem, North Carolina
| | - Yehuda Ringel
- University of North Carolina Medical Center, Chapel Hill, North Carolina
| | | | - Braden Kuo
- Department of Medicine, Massachusetts General Hospital, Boston, Massachusetts
| | - Tuba Esfandyari
- Department of Medicine, Kansas University Medical Center, Kansas City, Kansas
| | - Alok Gupta
- University of Buffalo VA Medical Center, Buffalo, New York
| | | | | | - Henry P. Parkman
- Department of Medicine, Temple University, Philadelphia, Pennsylvania
| | - Edy Soffer
- Cedars-Sinai Medical Center, Los Angeles, California
| | - Gregory E. Wilding
- Department of Biostatistics, State University of New York at Buffalo, Buffalo, New York
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Microwave initiated synthesis of polyacrylamide grafted guar gum (GG-g-PAM)—Characterizations and application as matrix for controlled release of 5-amino salicylic acid. Int J Biol Macromol 2010; 47:164-70. [DOI: 10.1016/j.ijbiomac.2010.05.004] [Citation(s) in RCA: 102] [Impact Index Per Article: 6.8] [Reference Citation Analysis] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 03/06/2010] [Revised: 04/19/2010] [Accepted: 05/05/2010] [Indexed: 11/20/2022]
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Abstract
The most widely used pharmacological therapies for obesity and weight management are based on inhibition of gastrointestinal lipases, resulting in a reduced energy yield of ingested foods by reducing dietary lipid absorption. Colipase-dependent pancreatic lipase is believed to be the major gastrointestinal enzyme involved in catalysis of lipid ester bonds. There is scant literature on the action of pancreatic lipase under the range of physiological conditions that occur within the human small intestine, and the literature that does exist is often contradictory. Due to the importance of pancreatic lipase activity to nutrition and weight management, the present review aims to assess the current body of knowledge with regards to the physiology behind the action of this unique gastrointestinal enzyme system. Existing data would suggest that pancreatic lipase activity is affected by intestinal pH, the presence of colipase and bile salts, but not by the physiological range of Ca ion concentration (as is commonly assumed). The control of secretion of pancreatic lipase and its associated factors appears to be driven by gastrointestinal luminal content, particularly the presence of acid or digested proteins and fats in the duodenal lumen. Secretion of colipase, bile acids and pancreatic lipase is driven by cholecystokinin and secretin release.
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Sen G, Pal S. A novel polymeric biomaterial based on carboxymethylstarch and its application in controlled drug release. J Appl Polym Sci 2009. [DOI: 10.1002/app.30762] [Citation(s) in RCA: 23] [Impact Index Per Article: 1.4] [Reference Citation Analysis] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 11/11/2022]
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Microwave initiated synthesis of polyacrylamide grafted carboxymethylstarch (CMS-g-PAM): Application as a novel matrix for sustained drug release. Int J Biol Macromol 2009; 45:48-55. [DOI: 10.1016/j.ijbiomac.2009.03.012] [Citation(s) in RCA: 77] [Impact Index Per Article: 4.8] [Reference Citation Analysis] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 02/16/2009] [Revised: 03/31/2009] [Accepted: 03/31/2009] [Indexed: 11/23/2022]
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Ibekwe VC, Fadda HM, McConnell EL, Khela MK, Evans DF, Basit AW. Interplay Between Intestinal pH, Transit Time and Feed Status on the In Vivo Performance of pH Responsive Ileo-Colonic Release Systems. Pharm Res 2008; 25:1828-35. [DOI: 10.1007/s11095-008-9580-9] [Citation(s) in RCA: 153] [Impact Index Per Article: 9.0] [Reference Citation Analysis] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 01/09/2008] [Accepted: 03/25/2008] [Indexed: 11/30/2022]
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Chen EP, Mahar Doan KM, Portelli S, Coatney R, Vaden V, Shi W. Gastric pH and gastric residence time in fasted and fed conscious cynomolgus monkeys using the Bravo pH system. Pharm Res 2007; 25:123-34. [PMID: 17612796 DOI: 10.1007/s11095-007-9358-5] [Citation(s) in RCA: 36] [Impact Index Per Article: 2.0] [Reference Citation Analysis] [Abstract] [MESH Headings] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 01/22/2007] [Accepted: 05/18/2007] [Indexed: 02/07/2023]
Abstract
PURPOSE To measure fasted and fed gastric pH and gastric residence time (GRT) in Cynomolgus monkeys using Bravo radiotelemetry capsules. METHODS Continuous pH measurements were recorded with Bravo capsules, which were either attached to the monkeys' stomach or administered as free capsules. Meals (either slurry or standard), were administered at designated times with monkeys chair-restrained during slurry meal ingestion. RESULTS From the attached capsule studies, the fasted gastric pH (~1.9-2.2) was consistent among monkeys. Under fasted conditions, pH spikes were infrequently observed (once every 7.9 min to 3.6 h) with peaks reaching pH 9.4 and having short durations (<1 min). After feeding, the gastric pH rose quickly and remained alkaline for approximately 4.5-7.5 h before returning to baseline. Although significantly different (p < 0.05), there was overlap between the fasted (153 +/- 87 min) and fed (436 +/- 265 (slurry) and 697 +/- 193 (standard) min) GRT due to considerable inter- and intra-subject variability. CONCLUSIONS Fasted gastric pH was similar between monkeys and literature human values. After a meal, the monkey gastric pH was elevated for a longer duration than that in human. The monkey GRT appears longer than that observed in human under both fasted and fed conditions, although this is likely dependent on the Bravo capsule size.
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Affiliation(s)
- Emile P Chen
- Department of Preclinical Drug Metabolism and Pharmacokinetics, GlaxoSmithKline, King of Prussia, PA 19406, USA.
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Grabovac V, Schmitz T, Föger F, Bernkop-Schnürch A. Papain: An Effective Permeation Enhancer for Orally Administered Low Molecular Weight Heparin. Pharm Res 2007; 24:1001-6. [PMID: 17372680 DOI: 10.1007/s11095-006-9226-8] [Citation(s) in RCA: 13] [Impact Index Per Article: 0.7] [Reference Citation Analysis] [Abstract] [MESH Headings] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 07/10/2006] [Accepted: 12/22/2006] [Indexed: 10/23/2022]
Abstract
PURPOSE The purpose of this study was to evaluate an effect of the proteolytic enzyme papain on permeation of low molecular weight heparin (LMWH) in vitro and in vivo. MATERIALS AND METHODS In vitro permeation studies were performed using rat small intestine as permeation barrier. In order to determine the ratio of papain to heparin resulting in the highest heparin permeation rate, molar ratios 1:1, 1:2 and 2:1 of papain to heparin were tested. Interactions of heparin with papain were investigated spectro-photometrically. For in vivo studies, 15 mg tablets containing heparin (13%), papain (64%) and hydroxyethylcellulose (22%) were orally administered to rats. RESULTS Since molar ratio papain to heparin 1:1 resulted in the highest permeation rate, it was used for in vivo studies. The results of binding studies of papain with heparin indicated a strong interaction between papain and heparin. Oral administration of tablets containing LMWH/papain/HEC resulted in sevenfold improvement of plasma anti-Xa activity in comparison to control. For tablets based on heparin/papain/HEC, a relative bioavailability of 9.1% vs. subcutaneous injection was obtained, whereas the relative bioavailability of control was 2.4%. CONCLUSION The co-administration of papain with heparin represents a new approach in improvement of absorption and bioavailability of orally administered heparin.
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Affiliation(s)
- Vjera Grabovac
- Institute of Pharmacy, Department of Pharmaceutical Technology, University of Innsbruck, Innrain 52, 6020, Innsbruck, Austria
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Abstract
Oral drug delivery to the colon has attracted significant attention during the past 20 years. Colon targeting is recognised to have several therapeutic advantages, such as the oral delivery of drugs that are destroyed by the stomach acid and/or metabolised by pancreatic enzymes. Sustained colonic release of drugs can be useful in the treatment of nocturnal asthma, angina and arthritis. Local treatment of colonic pathologies, such as ulcerative colitis, colorectal cancer and Crohn's disease, is more effective with the delivery of drugs to the affected area. Likewise, colonic delivery of vermicides and colonic diagnostic agents requires smaller doses. This article aims to provide an insight into the design and manufacturing considerations, and an evaluation of colonic drug delivery systems in order to understand why there are still few delivery technologies that have reached the market, despite intensive research in this field. For this purpose, various approaches to colon-specific drug delivery are discussed.
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Affiliation(s)
- Guy Van den Mooter
- Johnson & Johnson Pharmaceutical Research and Development, Turnhoutseweg 30, 2340 Beerse, Belgium.
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Schmitz T, Huck CW, Bernkop-Schnürch A. Characterisation of the thiol–disulphide chemistry of desmopressin by LC, μ-LC, LC-ESI-MS and Maldi-Tof. Amino Acids 2005; 30:35-42. [PMID: 16133762 DOI: 10.1007/s00726-005-0241-6] [Citation(s) in RCA: 11] [Impact Index Per Article: 0.6] [Reference Citation Analysis] [Abstract] [MESH Headings] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 07/22/2005] [Accepted: 07/23/2005] [Indexed: 10/25/2022]
Abstract
To date, the majority of therapeutic peptides and proteins have to be administered via parenteral routes, which are painful and inconvenient. In order to gain sufficient high blood concentrations after oral application, various barriers in the gastrointestinal tract have to be overcome. Apart from a poor membrane uptake and intense enzymatic degradation, this study will demonstrate that thiol-disulphide reactions are an underestimated essential part of the presystemic metabolism. Glutathione, integrative part of the antioxidant defence system in the gastrointestinal tract, may play an important role in the inactivation of orally given peptides and proteins. In order to verify this hypothesis, desmopressin which bears a single disulphide bond was used as model peptide drug. Desmopressin was incubated with GSH in various concentrations, and the extent of thiol/disulphide exchange reactions between the peptide drug and GSH was investigated in dependence on pH and ratio of reactants determined as a function of time via HPLC, LC-MS and Maldi-Tof-MS analyses. Results showed that desmopressin is degraded by 1% reduced glutathione at pH 4 and pH 5.5. In presence of 0.01%, 0.1% and 1% of reduced glutathione 6.1%, 19.4% and 52.1% of desmopressin, respectively, were degraded. The masses of the conjugates after deconvolution measured by liquid chromatography and electrospray ionisation mass spectrometric detection were m/z 1069.67, m/z 1376.50, m/z 1683.40 and m/z 2138. These molecular masses, confirmed by Maldi-Tof-MS analysis, correspond with the masses of conjugates expected in theory. Under defined conditions, these results reveal that thiol-disulphide exchange reactions have a considerable impact on the alteration of peptide drugs and proteins.
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Affiliation(s)
- T Schmitz
- Department of Pharmaceutical Technology, Institute of Pharmacy, Leopold-Franzens-University Innsbruck, Innsbruck, Austria
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38
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Johannessen EA, Wang L, Cui L, Tang TB, Ahmadian M, Astaras A, Reid SWJ, Yam PS, Murray AF, Flynn BW, Beaumont SP, Cumming DRS, Cooper JM. Implementation of Multichannel Sensors for Remote Biomedical Measurements in a Microsystems Format. IEEE Trans Biomed Eng 2004; 51:525-35. [PMID: 15000383 DOI: 10.1109/tbme.2003.820370] [Citation(s) in RCA: 98] [Impact Index Per Article: 4.7] [Reference Citation Analysis] [Abstract] [MESH Headings] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 11/10/2022]
Abstract
A novel microelectronic "pill" has been developed for in situ studies of the gastro-intestinal tract, combining microsensors and integrated circuits with system-level integration technology. The measurement parameters include real-time remote recording of temperature, pH, conductivity, and dissolved oxygen. The unit comprises an outer biocompatible capsule encasing four microsensors, a control chip, a discrete component radio transmitter, and two silver oxide cells (the latter providing an operating time of 40 h at the rated power consumption of 12.1 mW). The sensors were fabricated on two separate silicon chips located at the front end of the capsule. The robust nature of the pill makes it adaptable for use in a variety of environments related to biomedical and industrial applications.
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Affiliation(s)
- Erik A Johannessen
- Department of Electronics and Electrical Engineering, University of Glasgow, Rankine Building, Oakfield Avenue, Glasgow G12 8LT, UK.
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Cooper JM, Johannessen EA, Cumming DRS. Bridging the Gap Between Micro and Nanotechnology: Using Lab-on-a-Chip to Enable Nanosensors for Genomics, Proteomics, and Diagnostic Screening. LECTURE NOTES IN COMPUTER SCIENCE 2004. [DOI: 10.1007/978-3-540-30141-7_75] [Citation(s) in RCA: 5] [Impact Index Per Article: 0.2] [Reference Citation Analysis] [Track Full Text] [Subscribe] [Scholar Register] [Indexed: 12/22/2022]
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40
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Nakano Y, Kawamoto T, Takano Y. Phosphatase activities of rat intestinal enterocytes and their relation to diverse luminal pH, with special references to the possible localization of phytase along the brush border membrane. ARCHIVES OF HISTOLOGY AND CYTOLOGY 2001; 64:483-92. [PMID: 11838708 DOI: 10.1679/aohc.64.483] [Citation(s) in RCA: 7] [Impact Index Per Article: 0.3] [Reference Citation Analysis] [Abstract] [MESH Headings] [Track Full Text] [Subscribe] [Scholar Register] [Indexed: 11/11/2022]
Abstract
Phosphatase activities associated with the intestinal brush border membrane (BBM) of the rat were examined histochemically in relation to the characteristic environment of the intestine, where luminal pH fluctuates drastically between alkaline and acid pH ranges. Special attention was given to intestinal alkaline phosphatase (IALP) and phytase on the BBM. Whole body fresh-frozen sections of young rats and their rapidly frozen and freeze-substituted small intestines, embedded in Technovit 7100, were processed for the histochemical demonstration of phosphatase activity at three different pH values (9.2, 7.3, and 5.2), representing the deviation of luminal pH in vivo. Either an azo-dye method or lead-salt method was employed using naphthol AS-MX phosphate and ATP as substrate, respectively. With the azo-dye method, intense phosphatase reactions were demonstrated along the BBM at all three pH ranges. Phosphatase reactions of the BBM at pH 9.2 and 7.3 were abolished by L(+)-phenylalanine, heat pre-treatment, and EDTA chelation although some reaction remained at pH 7.3 after the treatment with EDTA or L(+)-phenylalanine. Phosphatase reactions of the BBM at pH 5.2 were resistant to L(+)-phenylalanine, L(+)-tartrate, PCMB and EDTA chelation, implying that the characteristics of the enzyme responsible for phosphohydrolysis at acid pH values differed from those at higher pH values. The lead-salt method in which ATP was used as substrate revealed intense reactions--which were dependent on Mg++ and stimulated by Ca++ and resistant to L(+)phenylalanine--to be localized along the BBM at alkaline and neutral pH values, but not at acid pH values. In vitro experiments showed progressive hydrolysis of naphthol AS-MX phosphate by purified phytase at pH 5.2, in a dose-dependent manner, and suggested the possible involvement of phytase in the phosphatase reactions of the BBM at acid pH. These data indicate that the phosphatase reactions at alkaline and neutral pH values, associated with the BBM of the rat intestine, represent IALP and Mg++/ Ca++-ATPase, while those at acid pH appear to correspond to phytase activity, something which has not been demonstrated by histochemical methods despite the availability of extensive data based on biochemical analyses.
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Affiliation(s)
- Y Nakano
- Graduate School of Tokyo Medical and Dental University, Japan
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41
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Nugent SG, Kumar D, Rampton DS, Evans DF. Intestinal luminal pH in inflammatory bowel disease: possible determinants and implications for therapy with aminosalicylates and other drugs. Gut 2001; 48:571-7. [PMID: 11247905 PMCID: PMC1728243 DOI: 10.1136/gut.48.4.571] [Citation(s) in RCA: 481] [Impact Index Per Article: 20.0] [Reference Citation Analysis] [Abstract] [MESH Headings] [Track Full Text] [Journal Information] [Submit a Manuscript] [Subscribe] [Scholar Register] [Indexed: 12/12/2022]
Abstract
Measurements of luminal pH in the normal gastrointestinal tract have shown a progressive increase in pH from the duodenum to the terminal ileum, a decrease in the caecum, and then a slow rise along the colon to the rectum. Some data in patients with ulcerative colitis suggest a substantial reduction below normal values in the right colon, while limited results in Crohn's disease have been contradictory. Determinants of luminal pH in the colon include mucosal bicarbonate and lactate production, bacterial fermentation of carbohydrates and mucosal absorption of short chain fatty acids, and possibly intestinal transit. Alterations in these factors, as a result of mucosal disease and changes in diet, are likely to explain abnormal pH measurements in inflammatory bowel disease (IBD). It is conceivable that reduced intracolonic pH in active ulcerative colitis impairs bioavailability of 5-aminosalicylic acid from pH dependent release formulations (Asacol, Salofalk) and those requiring cleavage by bacterial azo reductase (sulphasalazine, olsalazine, balsalazide), but further pharmacokinetic studies are needed to confirm this possibility. Reports that balsalazide and olsalazine may be more efficacious in active and quiescent ulcerative colitis, respectively, than Asacol suggest that low pH may be a more critical factor in patients taking directly pH dependent release than azo bonded preparations. Reduced intracolonic pH also needs to be considered in the development of pH dependent colonic release formulations of budesonide and azathioprine for use in ulcerative and Crohn's colitis. This paper reviews methods for measuring gut pH, its changes in IBD, and how these may influence current and future therapies.
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Affiliation(s)
- S G Nugent
- Department of Surgery, St George's Hospital Blackshaw Road, London, UK
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42
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Gnoth MJ, Kunz C, Kinne-Saffran E, Rudloff S. Human milk oligosaccharides are minimally digested in vitro. J Nutr 2000; 130:3014-20. [PMID: 11110861 DOI: 10.1093/jn/130.12.3014] [Citation(s) in RCA: 205] [Impact Index Per Article: 8.2] [Reference Citation Analysis] [Abstract] [MESH Headings] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 11/12/2022] Open
Abstract
In examining the functional aspects of human milk oligosaccharides (HMO), it is not known whether they are digested during the passage through the infant's gastrointestinal tract. HMO were prepared from individual milk samples (n = 6) and separated into neutral and acidic compounds by chromatography. These oligosaccharide fractions were studied for their digestibility by human salivary amylase, porcine pancreatic amylase and brush border membrane vesicles (BBMV) isolated from porcine small intestine; we also examined the effect of low pH on these structures. The characterization of HMO and their digestion products was performed by high-pH anion-exchange chromatography with pulsed amperometric detection (HPAEC-PAD) as well as TLC. It was shown that neither salivary amylase nor pancreatic amylase cleaved HMO. Only after a 2-h incubation with BBMV were slight modifications of the HMO observed. HPAEC-PAD analysis revealed two new components within the neutral oligosaccharide fractions; these were characterized by mass spectrometric analysis as lacto-N:-triose and galactose. Only lacto-N:-triose was present within digestion assays of oligosaccharides, which did not contain fucosyl or N:-acetylneuraminic acid residues. These results suggest that <5% of the HMO are digested in the intestinal tract. Hence, HMO may play a role as prebiotics or as factors influencing the local immune system of the intestine in breast-fed infants.
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Affiliation(s)
- M J Gnoth
- Research Institute of Child Nutrition, Dortmund, Germany. Institute of Nutrition, University of Giessen, Giessen, Germany
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43
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Liu JJ, Nilsson A, Duan RD. Effects of phospholipids on sphingomyelin hydrolysis induced by intestinal alkaline sphingomyelinase: an in vitro study. J Nutr Biochem 2000; 11:192-7. [PMID: 10827341 DOI: 10.1016/s0955-2863(00)00064-4] [Citation(s) in RCA: 17] [Impact Index Per Article: 0.7] [Reference Citation Analysis] [Abstract] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 12/19/2022]
Abstract
Digestion of dietary sphingomyelin (SM) is catalyzed by intestinal alkaline sphingomyelinase (SMase) and may have important implications in colonic tumorigenesis. Previous studies demonstrated that the digestion and absorption of dietary SM was slow and incomplete and that the colon was exposed to SM and its hydrolytic products including ceramide. In the present work, we studied the influences of glycerophospholipids and hydrolytic products of phosphatidylcholine (PC; i.e., lyso-PC, fatty acid, diacylglycerol, and phosphorylcholine) on SM hydrolysis induced by purified rat intestinal alkaline SMase in the presence of 10 mM taurocholate. It was found that various phospholipids including PC, phosphatidylserine (PS), phosphatidylinositol (PI), phosphatidylethanolamine (PE), and phosphatidic acid (PA) inhibit alkaline SMase activity in a dose-dependent manner, with the degree of inhibition being in the order PA > PS > PI > PC > PE. Similar inhibition was also seen in a buffer of pH 7.4, which is close to the physiologic pH in the middle of the small intestine. When the effects of hydrolytic products of PC were studied, lyso-PC, oleic acid, and 1,2-dioleoyl glycerol also inhibited alkaline SMase activity, whereas phosphorylcholine enhanced SMase activity. However, in the absence of bile salt, acid phospholipids including PA, PS, and PI mildly stimulated alkaline SMase activity whereas PC and PE had no effect. It is concluded that in the presence of bile salts, glycerophospholipids and their hydrolytic products inhibit intestinal alkaline SMase activity. This may contribute to the slow rate of SM digestion in the upper small intestine.
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Affiliation(s)
- J J Liu
- Department of Cell Biology 1, University Hospital of Lund, Lund, Sweden
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44
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Ewe K, Schwartz S, Petersen S, Press AG. Inflammation does not decrease intraluminal pH in chronic inflammatory bowel disease. Dig Dis Sci 1999; 44:1434-9. [PMID: 10489931 DOI: 10.1023/a:1026664105112] [Citation(s) in RCA: 64] [Impact Index Per Article: 2.5] [Reference Citation Analysis] [Abstract] [MESH Headings] [Track Full Text] [Journal Information] [Submit a Manuscript] [Subscribe] [Scholar Register] [Indexed: 12/12/2022]
Abstract
Intestinal inflammation may influence intraluminal pH. Profiles of the gastrointestinal pH were evaluated in 15 patients with active Crohn's disease of the ileocecal area. In addition, five patients with moderate (1) or severe (4) ulcerative colitis were studied. Fifteen healthy subjects served as controls. Intraluminal pH of the different parts of the gastrointestinal tract was measured by a free-floating pH-sensitive telemetering capsule. A metal sphere was attached to the capsule for exact localization by a metal detector. Physiological patterns of pH were maintained throughout the gastrointestinal tract including the inflamed segments. Median pH in the terminal ileum of the patients with Crohn's disease was 7.5 vs. 7.7 and in the rectum in ulcerative colitis 7.8 vs. 7.2 in the controls. In conclusion, intraluminal pH is not decreased by inflammatory changes in Crohn's disease and ulcerative colitis, allowing eudragit-coated pH-controlled-release formulations of mesalazine to dissolve in diseased areas also.
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Affiliation(s)
- K Ewe
- Medizinische Klinik und Poliklinik Johannes Gutenberg University Mainz, Germany
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45
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Abstract
Specific targeting of drugs to the colon is recognized to have several therapeutic advantages. Drugs which are destroyed by the stomach acid and/or metabolized by pancreatic enzymes are slightly affected in the colon, and sustained colonic release of drugs can be useful in the treatment of nocturnal asthma, angina and arthritis. Treatment of colonic diseases such as ulcerative colitis, colorectal cancer and Crohn's disease is more effective with direct delivery of drugs to the affected area. Likewise, colonic delivery of vermicides and colonic diagnostic agents require smaller doses. This article is aimed at providing insight into the design considerations and evaluation of colonic drug delivery systems. For this purpose, the anatomy and physiology of the lower gastrointestinal tract are surveyed. Furthermore, the biopharmaceutical aspects are considered in relation to drug absorption in the colon and hence various approaches to colon-specific drug delivery are discussed.
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Affiliation(s)
- R Kinget
- Laboratorium voor Farmacotechnologie en Biofarmacie, Katholieke Universiteit Leuven, Belgium
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46
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47
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Porter EM, van Dam E, Valore EV, Ganz T. Broad-spectrum antimicrobial activity of human intestinal defensin 5. Infect Immun 1997; 65:2396-401. [PMID: 9169780 PMCID: PMC175332 DOI: 10.1128/iai.65.6.2396-2401.1997] [Citation(s) in RCA: 172] [Impact Index Per Article: 6.1] [Reference Citation Analysis] [Abstract] [MESH Headings] [Grants] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 02/04/2023] Open
Abstract
Defensins are antibiotic peptides expressed in human and animal myeloid and epithelial cells. Due to the limited availability of natural peptides, the properties of human epithelial defensins have not been studied. We assayed the microbicidal activity of recombinant human intestinal defensin 5 (rHD-5) in the presence of salt (O to 150 mM NaCl) with varied pH (pH 5.5 to pH 8.5) and trypsin (25 and 250 microg/ml). rHD-5 exhibits microbicidal activity against Listeria monocytogenes, Escherichia coli, and Candida albicans. In contrast to cryptdins, the mouse intestinal defensins, rHD-5 is active against both mouse-virulent wild-type Salmonella typhimurium and its isogenic, mouse-avirulent phoP mutant. In the presence of salt, rHD-5 activity was reduced, and at 100 mM NaCl, activity against S. typhimurium was abolished. However, at all salt concentrations tested, rHD-5 remained bactericidal to L. monocytogenes. Activity against L. monocytogenes was not pH dependent but was diminished at pH 5.5 against wild-type S. typhimurium. This acid-induced resistance may have been mediated by the virulence gene regulator phoP, since the phoP mutant was equally sensitive at pH 5.5 and pH 7.4. In the presence of trypsin, rHD-5 was partially cleaved, but even then, rHD-5 at 100 microg/ml decreased the number of CFU of wild-type S. typhimurium by more than 99%. The persistence of microbicidal activity of rHD-5 under these conditions supports the notion that naturally occurring human intestinal defensin is an effective arm of mucosal host defense.
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Affiliation(s)
- E M Porter
- Department of Medicine, UCLA School of Medicine, Los Angeles, California 90095, USA
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48
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Affiliation(s)
- G Järnerot
- Department of Medicine, Orebro Medical Centre Hospital, Sweden
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49
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Abstract
In this article, we review the currently available techniques for measuring small intestinal and colonic transit. In addition, we describe the characteristics of an ideal test that provided the rationale for the development and validation of a gastrointestinal and colonic transit test at the Mayo Clinic. This new technique assesses regional transit of solid radiolabeled particles of the same size through the entire digestive tract and provides further insights into motor physiologic processes of the gut. By means of a delayed-release methacrylate-coated capsule, isotopically labeled pellets are delivered to the colon as a single bolus; thereby, dispersion of isotope throughout the small bowel is avoided because of the gradual emptying of chyme from the stomach. Similar pellets labeled with a different isotope can be used to assess gastric and small bowel transit. These new methods for measuring transit have also led to insights into the pathogenesis of unexplained gastrointestinal symptoms and disease states. Thus, we demonstrated that in healthy subjects, ileocolonic transfer of chyme occurs in boluses; this transfer is impaired in patients with myopathic pseudo-obstruction. The emptying rate of the proximal colon is an important determinant of the pathophysiologic features of colonic disease; thus, colonic transit is delayed in cases of severe idiopathic constipation. In contrast, rapid emptying of the proximal colon influences stool weight in diarrhea-predominant irritable bowel syndrome. An integrated approach for studying gastric, small bowel, and colonic transit by using the same radiolabeled particle provides a useful, clinically applicable method for evaluating gastrointestinal symptoms and for measuring motor function of the entire digestive tract without need for intubation; cost and radiation exposure are acceptable.
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Affiliation(s)
- M R von der Ohe
- Gastroenterology Research Unit, Mayo Clinic, Rochester, MN 55905
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50
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Lillienau J, Schteingart CD, Hofmann AF. Physicochemical and physiological properties of cholylsarcosine. A potential replacement detergent for bile acid deficiency states in the small intestine. J Clin Invest 1992; 89:420-31. [PMID: 1371123 PMCID: PMC442868 DOI: 10.1172/jci115601] [Citation(s) in RCA: 39] [Impact Index Per Article: 1.2] [Reference Citation Analysis] [Abstract] [MESH Headings] [Grants] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 11/17/2022] Open
Abstract
The properties of cholylsarcosine (the synthetic N-acyl conjugate of cholic acid with sarcosine [N-methylglycine]) were examined to determine its suitability as a bile acid replacement agent for conditions of bile acid deficiency in the small intestine, which causes fat malabsorption. Previous studies in rodents had shown that the compound was well transported by the liver and ileum and underwent neither deconjugation nor dehydroxylation during enterohepatic cycling. By 1H-nuclear magnetic resonance, cholylsarcosine was found to exist in dilute aqueous solution as an almost equimolar mixture of two geometric isomers--cis and trans (around the amide bond)--in contrast to cholylglycine, which was present entirely in the trans form. The critical micellization concentration was 11 mmol/liter, similar to that of cholylglycine (10 mmol/liter). By nonaqueous titrimetry, the pKa' of cholylsarcosine was 3.7, only slightly lower than that of cholylglycine (3.9). Cholylsarcosine was poorly soluble below pH 3.7, but highly soluble above pH 4. In vitro, cholylsarcosine behaved as cholylglycine with respect to promoting lipolysis by lipase/colipase. There was little difference between cholylsarcosine and cholylglycine in their solubilization of an equimolar mixture of oleic acid, oleate, and monoolein (designed to simulate digestive products of triglyceride) or in their solubilization of monooleyl-glycerol alone. When a [3H]triolein emulsion with either cholylsarcosine or cholyltaurine was infused intraduodenally in biliary fistula rats, recovery of 3H in lymph was 52 +/- 10% (mean +/- SD) for cholylsarcosine and 52 +/- 11% for cholyltaurine. When perfused into the colon of the anesthetized rabbit, cholylsarcosine (5 mmol/liter) did not influence water absorption or permeability to erythritol, in contrast to chenodeoxycholate, which induced vigorous water secretion and caused erythritol loss. We conclude that cholylsarcosine possesses the physicochemical and physiological properties required for a suitable bile acid replacement in deficiency states.
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Affiliation(s)
- J Lillienau
- Department of Medicine, University of California, San Diego, La Jolla 92093
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