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Biomedical subjects

H Sankaran

Publications and source records attributed to H Sankaran.

47 records · Page 3Linked to original sources
PubMed1978

Sphincteric mechanism of the main pancreatic duct in the dog. An experimental model of the isolated sphincteric preparation.

This study describes an in vitro experimental model of the sphincter at the lower end of the main pancreatic duct in the dog. This model, employing a drop counter to measure the drop rate, monitors the perfusion rate of Tyrode through the sphincter. Acetylcholine (ACh), employed to establish the sensitivity and viability of the isolated sphincter, produced a contraction of the sphincter which was concentration-response related. Saline, as a control, atropine and hexamethonium did not affect the drop rate. Atropine (20 microgram) partially abolished the contraction produced by 50 microgram of ACh; hexamethonium (50 microgram) did not have an effect. Caerulein 50 microgram produced a relaxation of the sphincter; adrenaline 50 microgram a contraction. Both sympathetic and parasympathetic mechanisms seem to play a role in the regulation of sphincteric activity of the main pancreatic duct in dogs.

Acetylcholine↗
PubMed1976

Experimental studies on the aetiology of acute scorpion pancreatitis.

This study examined the action of the venom of the scorpion Tityus trintatis on the pancreas and gastrointestinal tract in anaesthetized dogs, on the isolated extracorporeal haemoperfused canine pancreas and on the isolated canine sphincter of Oddi. The venom induces exocrine secretion in both the isolated and intact pancreas and causes contraction of the isolated sphincter of Oddi. These results are discussed in relation to the pathogenesis of acute scorpion pancreatitis and possibly of some other forms of acute pancreatitis.

Acute Disease↗
PubMedDate not supplied

Attempts to prepare 'insulin-free plasma' from human subjects: effects of serial dilution and insulin recovery studies on immunoreactive insulin activity of partially insulin-free plasma.

The reason for attempts to prepare insulin-free plasma from human plasma is discussed. Binding agent, employed to prepare insulin-free plasma, had a capacity to bind 40% of insulin in the system. Insulin recovery from the filtrate of human standard insulin-binding agent reaction was 60%. Human plasma incubated with binding agent gave a filtrate--partially insulin-free plasma (PIFP)--which contained significantly higher amounts of insulin compared to calculated values. Insulin in PIFP was not augmented by serial dilution. Human standard insulin added to PIFP was recovered in full and the mixture was not dilution augmentable. Incubation of human plasma--human standard insulin (106 microunits/ml) mixture with binding agent gave a PIFP which had 60% of total insulin in the mixture. Dialysis did not alter the immunoreactive insulin activity of plasma. Dialysed samples showed augmentation of insulin activity on serial dilution. These observations strongly suggest the presence of a high molecular-weight, insulin-like inhibitory component in human plasma.

Antigens↗
PubMedDate not supplied

Bioassayable cholecystokinin in the brain of the goldfish, Carassius auratus.

Cholecystokinin (CCK)-gastrin peptides are shown to be present in the brain of all the species ranging from coelenterates to mammals. Differentiation between CCK and gastrin, presumed to be evolved from a common ancestral cerulein-like peptide, has been suggested to occur at the level of the amphibians. We examined the presence of bioassayable CCK, as determined by its potency to stimulate enzyme secretion from isolated rat pancreatic acini, in the brain of the goldfish Carassius auratus, a more primitive vertebrate than the amphibian. Among the various regions tested, the brain stem, telencephalon and spinal cord possess the highest levels of bioassayable CCK followed in decreasing order by gustatory lobes, optic tectum and duodenum. No detectable levels of CCK were found in the cerebellum. The observed bioactivity was not due to gastrin because: radioimmunoassay of the brain homogenates for gastrin revealed very low or nondetectable levels of gastrin; amylase release dose-response curves for standard CCK8 and the brain homogenate were identical; and proglumide, a competitive antagonist of CCK8, inhibited homogenate CCK-induced enzyme release with a parallel rightward shift in the dose-response curve. These observations provide evidence for the distinct presence of CCK in the brain of the goldfish suggesting that the differentiation of CCK as a distinct neuropeptide, from that of gastrin, occurs at the level of Osteichthyes (bony fish).

Amino Acid Sequence↗
PubMedDate not supplied

Isolation and characterization of biologically active and inactive cholecystokinin-octapeptides from human brain.

Cholecystokinin-like immunoreactivity (CCK-LI) in 0.9 kg human brain was extracted by 2% trifluoroacetic acid at 4 degrees C. Sephadex G50 gel filtration of crude extract revealed one main molecular form of CCK, detected by a carboxy-terminal antibody (5135), that eluted in the position of CCK8. When the CCK-LI in the extract was purified by affinity chromatography using another carboxyl-terminal CCK antibody followed by several steps of reverse phase high pressure liquid chromatography (HPLC), a component was isolated that was found by sequence analysis to be identical to the carboxyl-terminal CCK-octapeptide of porcine CCK33, isolated from intestinal mucosa, and to CCK-octapeptide, isolated from sheep brain. This component possessed comparable biological potencies to synthetic sulfated CCK8 in eliciting amylase release and in competitively displacing radioiodinated CCK33 from isolated mouse pancreatic acini. Furthermore, it exhibited a similar binding characteristic to CCK8 in binding to specific receptors on mouse brain cortical particulate preparations. On high pressure liquid chromatography another minor, earlier eluting immunoreactive peak was observed, which had the same amino acid composition and sequence as CCK8. These findings suggested that this material was oxidized CCK8. This earlier eluting component, exhibiting CCK8-like immunoreactivity, did not induce amylase release from acini and had no or minimal effect in inhibiting tracer CCK33 binding to receptors on isolated acini or on mouse brain cortical particulate preparations at the concentrations tested.

Amino Acids↗