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Respiratory system
Published in Jagdish M. Gupta, John Beveridge, MCQs in Paediatrics, 2020
Jagdish M. Gupta, John Beveridge
In cystic fibrosis there are no changes in intestinal disaccharidase levels. Over the last 20 years the life expectancy of cystic fibrosis patients has increased from 10 to more than 20 years. The incidence in the offspring of unaffected siblings is approximately 1 in 300 (1/3x¼×1/25). Neonatal bowel obstruction is usually due to meconium ileus or may be due to ileal atresia with or without meconium peritonitis. Neonatal screening with immunoreactive trypsin gives both false positive and false negative results.
Inherited Differences in Alpha1-Antitrypsin
Published in Stephen D. Litwin, Genetic Determinants of Pulmonary Disease, 2020
Active site titration of trypsin [33] makes it possible to determine the amount of active enzyme in a preparation. The inhibition values for serum (and other biologic fluids) are, of course, lower when a correction factor for active trypsin is used. Corrected values for normal human serum ranged from 0.5 to 0.9 mg trypsin inhibited with a mean of 0.64 ± 0.25 SD mg/ml.
Hereditary Pancreatitis
Published in Dongyou Liu, Handbook of Tumor Syndromes, 2020
The PRSS1 gene on chromosome 7q34 spans 12.8 kb and encodes a 247 aa, 26.5 kDa cationic trypsinogen (or trypsinogen-1, an inactive form of trypsin), which is a member of the trypsin family of serine proteases. Secreted by the pancreas, trypsinogen is cleaved of an eight-amino-acid trypsinogen activation peptide (TAP) by enterokinase to form active trypsin in the small intestine. TAP may be also cleaved by trypsin in the presence of calcium and association with a binding site formed in the activation region. The resultant active (mature) trypsin is an endopeptidase that cleaves peptide chains following a lysine or arginine, and converts inactive zymogens produced by the pancreas into active digestive enzymes in the duodenum upon food exposure. A second calcium-binding site in trypsinogen as well as trypsin may be occupied by calcium, which prevents trypsin degradation by trypsin on the autolysis site (Arg-122), and by chymotrypsin C (CTRC) at Leu-81 within the calcium binding site [9].
Recent advances in proteolytic stability for peptide, protein, and antibody drug discovery
Published in Expert Opinion on Drug Discovery, 2021
Xianyin Lai, Jason Tang, Mohamed E.H. ElSayed
The pancreas produces trypsinogen, an inactive precursor of trypsin. Trypsinogen is then secreted into the duodenum through the pancreatic duct. Once in the small intestine, the trypsinogen is activated by the enzyme enteropeptidase via proteolytic cleavage [54,55]. Trypsin is an endopeptidase and breaks peptide bonds down via a serine catalysis mechanism at an optimal pH of 7.5–8.5 [56]. The salmon calcitonin is a small peptide of 32 amino acids with a molecular weight of 3,432 Da and is a more potent analog of human calcitonin [57]. The salmon calcitonin was incubated with 0.5 μM trypsin in a sodium acetate (50 mM) buffer and it was completely degraded in 15 min [58]. The human granulocyte colony stimulating factor (G-CSF) is a major cytokine regulator of neutrophilic granulocytes and is able to stimulate the growth of neutrophil colonies from human bone marrow progenitor cells with a molecular weight of about 30,000 Da [59]. The incubation of 100 ug/ml of G-CSF with 1 ug/ml of trypsin revealed that G-CSF was susceptible to trypsin digestion and had about 30% intact protein at 4 h incubation [60].
Trypsinogen and chymotrypsinogen: potent anti-tumor agents
Published in Expert Opinion on Biological Therapy, 2021
Aitor González-Titos, Pablo Hernández-Camarero, Shivan Barungi, Juan Antonio Marchal, Julian Kenyon, Macarena Perán
The pancreas plays a very important role in the digestive function through the secretion of several enzymes necessary for the degradation of nutrients. These enzymes are secreted by acinar cells as zymogens (inactive forms also known as (pro)enzymes) [3]. Once secreted, they are transferred to the small intestine where they are activated. The most studied zymogens are Trypsinogen and Chymotrypsinogen. In the case of Trypsinogen, it is activated to Trypsin in the small intestine by enterokinase. Once activated, it is capable of activating the rest of the pancreatic zymogens, including Chymotrypsinogen into Chymotrypsin [4]. A failure in the production of these proteins can cause poor absorption of nutrients, the most common diseases that lead to exocrine pancreatic insufficiency are chronic pancreatitis and cystic fibrosis [5].
Frederick Banting’s actual great idea: The role of fetal bovine islets in the discovery of insulin
Published in Islets, 2021
Banting and Best freely acknowledged that the studies of Ibrahim21 and Carlson and Drennan22 influenced them.10 As for Ibrahim’s study, the importance to Banting of not having to deal with trypsin in fetuses up to 4 months gestation is obvious. Carlson and Drennan had found that pregnant dogs undergoing pancreatectomies near term did not become diabetic and speculated: “the internal secretion of the fetal pancreas passes through the uterine membranes in sufficient quantity to prevent diabetes in the mother”22p393 However, it should be noted that this conclusion was highly tenuous as it was based on a small number of dogs and, since it had been performed in 1910 before blood glucose measurements were practical,23 only a few urine sugar measurements over 2–3 d. Banting and Best wrote: “The most natural interpretation of Carlson’s result is that the pancreas of the fetus furnishes to the mother an internal secretion which is necessary for the metabolism of sugar.”10p464 However, they cautiously noted that another investigator had been unable to replicate Carlson’s study.10