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StomachGastric Secretions, Motility, Digestion and Vomiting
Published in Peter Kam, Ian Power, Michael J. Cousins, Philip J. Siddal, Principles of Physiology for the Anaesthetist, 2020
Peter Kam, Ian Power, Michael J. Cousins, Philip J. Siddal
The chief (peptic) cells at the base of the gastric gland produce pepsinogen I, which is stored as intracellular storage granules. Pepsinogen I is produced by mucous glandular cells. Pepsinogen is released by exocytosis following stimulation by cholinergic, muscarinic and β-adrenergic influences. In the acidic pH of the stomach, autocatalytic cleavage of pepsinogen produces pepsin, a proteolytic enzyme that facilitates protein digestion.
Protein and amino acids
Published in Jay R Hoffman, Dietary Supplementation in Sport and Exercise, 2019
The process of protein digestion is a critical component relative to amino acid bioavailability. With very few exceptions, dietary proteins are not absorbed in the small intestine for subsequent delivery to the portal circulation. Instead, they must first be digested into amino acids or di- and tripeptides. This occurs due to the stomach secreting pepsinogen, which is then converted to the active protease, pepsin, by stomach acid. The proteases trypsin, chymotrypsin and carboxypeptidases, secreted from the pancreas, are also involved. By way of the gastric and pancreatic proteases, dietary proteins are hydrolyzed within the lumen of the small intestine predominantly into oligopeptides for uptake by the enterocytes of the small intestine. Along the lumenal border of the small intestine, the brush border contains additional peptidases that function to further hydrolyze lumenal peptides. Along the basement membrane, the enterocyte contains sodium-dependent amino acid transporters specific for acidic, basic and neutral amino acids. These transporters are responsible for releasing the amino acids into the cytoplasm. Once inside the enterocyte, the majority of di- and tripeptides are digested into amino acids by cytoplasmic peptidases and exported across the basolateral membrane into the portal circulation by non-sodium-dependent transporters (9).
The digestive system
Published in Laurie K. McCorry, Martin M. Zdanowicz, Cynthia Y. Gonnella, Essentials of Human Physiology and Pathophysiology for Pharmacy and Allied Health, 2019
Laurie K. McCorry, Martin M. Zdanowicz, Cynthia Y. Gonnella
Pepsinogen is produced by the chief cells. Within the lumen of the stomach, this precursor molecule is split by HCl to form the active enzyme, pepsin. Optimally active at an acidic pH (pH = 2), pepsin begins protein digestion by fragmenting the proteins into smaller peptide chains.
Helicobacter Pylori Related Gastric Cancer Screening and Cost-Effectiveness Analysis: A Hospital-Based Cross-Sectional Study (SIGES)
Published in Nutrition and Cancer, 2022
Wen Xiang, Rui Wang, Dan Bai, Tian-Hang Yu, Xin-Zu Chen
Hp-GCS may potentially consider several serologic factors of virulent Hp strains, while Hp-GCS can combine certain tumor biomarkers or precancerous lesion-associated biomarkers (50). Cytotoxin-associated gene A (CagA), vacuolating cytotoxin A (VacA), helicobacter cysteine-rich protein C (HcpC), and chaperonin (GroEL), etc, which might be informative factors of virulent Hp strains in predicting gastric cancer (28, 51). Pepsinogens and gastrin-17 were associated with precancerous lesions of gastric cancer (16). Studies found the serologic pepsinogen test could be used as a supplementary screening test for high-risk individuals, but might not be ideal for gastric cancer itself (52, 53). Gastrin-17 was a serologic marker, which could reflect the function of gastric mucosa and predict gastric cancer by increasing level along with decreasing pepsinogen levels (54, 55). There were many reports on gastric cancer screening related to tumor biomarkers (56, 57). Commonly, higher levels of serologic CEA, CA724, CA125, and CA199, etc, were associated with gastric cancer risk, which could be considered as supplementary tests in the gastric cancer screening (34, 58). Besides Hp, some other pathogens might be associated with gastric cancer risk, such as Epstein-Barr virus (EBV), hepatitis B virus (HBV), human cytomegalovirus (CMV), human papillomavirus (HPV), and John Cunningham virus (JCV) (59–61). All these factors can be investigated on the effectiveness and cost-effectiveness in gastric cancer screening.
Narrow-band imaging combined with salivary pepsin to diagnose patients with laryngopharyngeal reflux
Published in Acta Oto-Laryngologica, 2021
Pepsin is a proteolytic enzyme whose precursor pepsinogen is produced only in the stomach. Therefore, an increased pepsin level in the saliva is considered a specific biomarker for gastric reflux or LPR. Detecting salivary pepsin using the fibrinogen digestion method, western blot analysis, and enzyme-linked immunosorbent assay (ELISA) is considered to be convenient and non-invasive [4]. Given the non-invasive nature of this test, it was considered to be a useful method in the diagnosis of gastroesophageal reflux disease [19]. In a study with 58 patients with GERD (diagnosed by esophagitis and/or abnormal pH) compared to 51 controls, a salivary pepsin test was performed with an 81% positive predictive value and a 78% negative predictive value [20]. In our study, we initially defined the threshold of pepsin as 33 ng/mL through ROC analysis. Further analysis showed that salivary pepsin levels were significantly correlated with RFS/RSI scores which means that salivary pepsin measurements have compared well against RFS/RSI score system.
Educational intervention can improve appropriateness of acid suppression therapy in hospitalized geriatric patients
Published in Journal of Community Hospital Internal Medicine Perspectives, 2019
Sankalp Dwivedi, Jaya Edukulla, Sindhu Rajendra, Sandesh Murali, Serge A. Sorser, Marc S. Piper, Michael Piper, Bradley J. Warren, Harsha Ramchandani
Gastric acid plays an essential role in the digestion of protein by converting pepsinogen to the active form, pepsin. It also prevents against enteric infection, bacterial overgrowth and facilitates the absorption of vitamin B12, non-heme iron, and medications such as calcium and thyroxin [1]. Consequences of hypochlorhydria have been well defined in the literature: (1) Osteoporosis and Hip Fracture [2]; (2) Hospital acquired pneumonia and community acquired pneumonia [3,4]; (3) Clostridium difficile infection [5]; (4) Vitamin B 12 deficiency [6]; (5) Alteration in the lower intestinal microflora [7]; (6) Various forms of kidney injury have also been linked to the Proton Pump Inhibitors (PPIs) use such as acute allergic interstitial nephritis, acute kidney injury, increased incidence of chronic kidney disease and progression to end stage renal disease [8].