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Biomedical subjects

M Seno

Publications and source records attributed to M Seno.

At least 91 records · Page 5Linked to original sources
PubMed1985

Vagal regulation of GRP, gastric somatostatin, and gastrin secretion in vitro.

The effect of electrical stimulation of the vagus nerves on the release of immunoreactive gastrin-releasing peptide (GRP), gastrin, and somatostatin was investigated using the isolated perfused rat stomach. Electrical stimulation (10 Hz, 1 ms duration, 10 V) of the peripheral end of the subdiaphragmatic vagal trunks produced a significant increase in both GRP and gastrin but a decrease in somatostatin. The infusion of atropine sulfate at a concentration of 10(-5) M augmented GRP release and reversed the decrease in somatostatin release in response to vagal stimulation to an increase above basal levels. However, the gastrin response to vagal stimulation was not affected by atropine. The infusion of hexamethonium bromide at a concentration of 10(-4) M significantly suppressed GRP release but did not affect gastrin secretion in response to vagal stimulation. On the other hand, the somatostatin response to vagal stimulation was completely abolished by hexamethonium. These findings lead us to conclude that the intramural GRP neurons might play an important role in the regulation of gastrin as well as somatostatin secretion and that somatostatin secretion may be controlled not only by a cholinergic inhibitory neuron but also by a noncholinergic, e.g., peptidergic stimulatory neuron, both of which may be regulated through preganglionic vagal fibers via nicotinic receptors. In addition, because the infusion of 10(-7) M GRP suppressed the somatostatin secretion, we suggest that either GRP should be excluded from the list of candidates for the noncholinergic stimulatory neurotransmitter for somatostatin secretion or that there are different mechanisms of action for endogenous and exogenous GRP.

Animals↗
PubMed1985

Effects of insulin on altered mineral and vitamin D metabolism in streptozotocin-induced diabetes.

In order to ascertain whether or not abnormal mineral and vitamin D metabolism in diabetes can be reversed by insulin therapy, plasma calcium, ionized calcium, phosphorus, parathyroid hormone (PTH) and vitamin D metabolites were measured in control, streptozotocin (STZ) diabetic and insulin-treated diabetic rats. Blood glucose levels in diabetic rats treated with insulin decreased to normal. The low plasma calcium and ionized calcium levels in diabetic rats were found to be normal in insulin-treated diabetic rats. An elevated PTH level was observed in the diabetic group, but it was at normal levels in the insulin-treated diabetic group. Plasma 25-hydroxyvitamin D (25(OH)D) and 24,25-dihydroxyvitamin D (24,25(OH)2D) in the diabetic group were decreased compared to those in control rats, but these were also fully restored to control levels by insulin therapy. However, plasma 1,25-dihydroxyvitamin D (1,25(OH)2D) levels in the untreated diabetic group tended to be lower than in controls, and the values in insulin-treated rats were significantly decreased compared to the control group. The ratio of 1,25(OH)2D to 25(OH)D in diabetic rats was higher than in controls, but it was decreased after insulin therapy and was significantly lower than in the control group. It is suggested, therefore, that the negative calcium balance and decreased 25(OH)D and 24,25(OH)2D levels are derived from the metabolic derangement due to the insulin deficiency. Furthermore, insulin seems to suppress the conversion of 25(OH)D to 1,25(OH)2D in experimental diabetes in vivo.

Animals↗
PubMed1984

A teratogenicity study of Phloxine B in ICR mice.

Pregnant Jcl:ICR mice were given Phloxine B in the diet at concentrations of 0, 1, 3 and 5% from the morning of day 6 through day 16 of gestation. The mice were killed on day 18 and foetuses were examined for external, visceral and skeletal anomalies. A significant decrease in body-weight gain was observed in all of the treated groups. Among the dams in the high-dose group, two maternal deaths, one abortion and a significant increase in liver weight were observed. A dose-related incidence of splitting of the cervical vertebral arches (nos 3-6) was noted in all of the treated groups, but this anomaly was not found in the controls. The total incidence of skeletal anomalies was also dose related and was significantly increased at the 3 and 5% dose levels. It was concluded that Phloxine B was teratogenic in mice at dietary levels of 3 and 5%, levels which resulted in maternal toxicity, and that a finding suggesting a teratogenic effect (split cervical arches) was also noted at the 1% dose level.

Animals↗
PubMed1984

Changes in insulin, somatostatin, and glucagon secretion during the development of obesity in ventromedial hypothalamic-lesioned rats.

Changes in insulin, somatostatin, and glucagon secretion during the development of obesity in rats after ventromedial hypothalamic (VMH) lesions were evaluated by measuring fasting hormone levels and their secretion from the isolated perfused pancreas. Fasting peripheral insulin levels were not altered 1 week after the VMH lesions but became progressively elevated at 3-4, 8-9, and 11-12 weeks compared to the values in sham-operated and age-matched control rats. In the portal vein, insulin levels also progressively increased in VMH-lesioned rats, but the portal-peripheral gradient of insulin in the later phase of VMH obesity was significantly lower than in the early phase after VMH lesions. On the contrary, the arginine-induced insulin release from the perfused pancreas was highest at 1 week and gradually decreased thereafter, although it continued to remain higher than that of controls. The perfusate somatostatin response to arginine also was exaggerated in the VMH-lesioned rats. However, both the peripheral glucagon level and the glucagon secretion from the perfused pancreas of the VMH-lesioned rats were not significantly different from the controls. These results show that VMH lesions result in an increased insulin and somatostatin secretion. Using the cyclically perfused liver in situ, we have found that the hepatic extraction rate of insulin is indeed reduced in rats 8-9 weeks after VMH lesioning, and so have at least partly accounted for the decreased portal-peripheral gradient of insulin in the later VMH postoperative phase.

Animals↗
PubMed1984

Relationship between bactericidal and phagocytic activities of peritoneal macrophages induced by irritants.

Cellular accumulation to the peritoneal cavity and modification of various functions of peritoneal macrophages were observed in mice injected intraperitoneally (ip) with thioglycollate medium (TG), liquid paraffin, proteose peptone and Corynebacterium parvum. The cellular composition of peritoneal exudates at 4 days after injection of irritants was almost the same in all the groups and the proportion of macrophages was increased approximately 4 times more than nontreated controls. The ability to kill Listeria monocytogenes and to generate chemiluminescence (CL) were augmented strongly in C. parvum-induced macrophages, while depressed in TG-induced macrophages. The activities of liquid paraffin- or proteose peptone-induced macrophages were almost the same as those in nontreated controls. However, the ability to phagocytose native sheep erythrocytes was greatly augmented both in C. parvum- and TG-induced macrophages. There is thus a discrepancy between bactericidal activity and phagocytic activity among macrophages induced with various irritants.

Animals↗
PubMed1983

Expression of human immunoglobulin E epsilon chain cDNA in E. coli.

Using the cDNA of human epsilon chain, three expression plasmids that code directly the constant portion of the epsilon chain (C epsilon 1-C epsilon 4, C epsilon 2-C epsilon 4 and C epsilon 3-C epsilon 4 domains) were constructed. These epsilon chain peptides were synthesized in E. coli under the control of the trp promoter-operator. The bacterially produced peptides have the antigenicity of human epsilon chain and gave the molecular weights equal to the values calculated from the amino acid sequence of the constructed plasmids.

Base Sequence↗
PubMed1983

Molecular cloning and nucleotide sequencing of human immunoglobulin epsilon chain cDNA.

DNA complementary to mRNA of human immunoglobulin E heavy chain (epsilon chain) isolated and purified from U266 cells has been synthesized and inserted into the PstI site of pBR322 by G-C tailing. This recombinant plasmid was used to transform E. coli chi 1776 to screen 1445 tetracycline resistant colonies. Nine clones (pGETI - 9) containing cDNA coding for the human epsilon chain were recognized by colony hybridization and Southern blotting analysis with a nick-translated human IgE genome fragment. The nucleotide sequence of the longest cDNA contained in pGET2 was determined. The results indicate that the sequence of 1657 nucleotides codes for 494 amino acids covering a part of the variable region and all of the constant region of the human epsilon chain. Most of the amino acid sequence deduced from the nucleotide sequence is in substantial agreement with that reported. Furthermore a termination codon after the -COOH terminal amino acid marks the beginning of a 3' untranslated region of 125 nucleotides with a poly A tail. Taking this into account, the structure of the human epsilon chain mRNA, except a part of the 5' end, is conserved fairly well in the cDNA insert in pGET2.

Amino Acid Sequence↗
PubMed1983

Mechanism of protection during the early phase of a generalized viral infection. I. Contribution of phagocytes to protection against ectromelia virus.

Effects of carrageenan and gamma-irradiation on virus titre in the liver were observed after intravenous inoculation of 8 X 10(3) p.f.u. of ectromelia virus which was not lethal for untreated mice. Trapping of virus by the liver within 30 min and an initial transient reduction in titre by day 1 were not affected by gamma-irradiation but were inhibited by pretreatment with carrageenan. An increase from day 1 to day 3 was not affected by gamma-irradiation but was augmented by pretreatment with carrageenan. Therefore, protection within 3 days may depend principally upon carrageenan-sensitive and irradiation-resistant cells, namely, fixed macrophages. Elimination of virus from day 4 to day 7 depended upon cell-mediated immunity. When carrageenan was given 3 days after virus inoculation, the titre of virus increased progressively from day 4 ultimately to kill the hosts. The cytotoxic activity of spleen cells against infected target cells was raised in carrageenan-treated mice as well as in untreated mice. Immune elimination of virus may be mediated by a mechanism requiring the cooperation of sensitized T lymphocytes and blood monocytes.

Animals↗