Biomedical subjects

H Muto

Publications and source records attributed to H Muto.

150 records · Page 9Linked to original sources

PubMedDate not supplied

Effects of oxytocin, arginine-vasopressin and lysine-vasopressin on insulin and glucagon secretion in sheep.

The effects of the posterior-pituitary peptides oxytocin (OT), arginine-vasopressin (AVP) and lysine-vasopressin (LVP) on insulin and glucagon secretion were examined in adult sheep. Each peptide was injected intravenously at doses from 1 to 3000 pmol kg-1. All three peptides increased plasma insulin and glucagon concentrations, but their dose-response relationships revealed differences between them. The maximal insulin responses induced by OT and AVP were very similar, but the threshold and maximal doses of AVP for increasing plasma insulin were higher than those of OT. OT and AVP had the same activity for stimulating glucagon secretion in respect of the threshold and maximal doses and the maximal hormone response. LVP also increased plasma insulin and glucagon concentrations, but it had the weakest activity for stimulating both hormones. These results suggest that in sheep posterior-pituitary peptide may play a role in regulating nutrient metabolism by influencing pancreatic hormone secretion.

Animals↗

PubMedDate not supplied

Effects of C-terminal fragments of cholecystokinin on plasma insulin and glucagon concentrations in sheep.

The effects of three C-terminal fragments of cholecystokinin (CCK) (CCK-8-sulphated form [SF], CCK-8-non-sulphated form [NSF] and CCK-4) on insulin and glucagon secretion were examined in sheep in vivo. Each CCK fragment was injected intravenously at a wide range of doses (1 pmol to 3 x 10(5) pmol kg-1). CCK-8(SF) had the lowest threshold dose (10 pmol kg-1) and a maximal response dose of 10(3) pmol kg-1 for increasing plasma insulin concentration; the respective threshold doses of CCK-8(NSF) and CCK-8 for increasing plasma insulin were 30 and 100 times greater than that of CCK-8(SF). A maximal insulin response was not obtained at the highest doses of CCK-8(NSF) or CCK-4 tested (3 x 10(3) and 3 x 10(5) pmol kg-1, respectively). These results indicate that CCK-A type receptors rather than CCK-B receptors may be involved in CCK-induced insulin secretion in sheep. None of the CCK fragments affected plasma glucagon concentration. The lack of a glucagon response to exogenous CCK-fragments may be one of the characteristics of the endocrine pancreatic responses of ruminant species.

Animals↗

PubMedDate not supplied

Dioxins in cigarette smoke.

Dioxins in cigarettes, smoke, and ash were determined using gas chromatography/mass spectrometry. The total concentration of polychlorinated dibenzo-p-dioxins (PCDDs) in cigarette smoke was approximately 5.0 micrograms/m3 at the maximum level, whereas various congeners from tetra-octa-chlorodibenzo-p-dioxin (-CDD) were detected. Particullary, the total concentration of hepta-CDD congeners was the highest among these congeners. Mass fragmentograms of various PCDD congeners were similar to those in flue gas samples collected from a municipal waste incinerator. The PCDD congeners that were not present in the cigarettes were found in the smoke samples. The 2,3,7,8-TCDD toxic equivalent value--an index for effects on humans--for total PCDDs in smoke was 1.81 ng/m3 using the toxic factor of the United States Environment Protection Agency. Daily intake of PCDDs by smoking 20 cigarettes was estimated to be approximately 4.3 pg.kg body weight/day. This value was close to that of the ADIs: 1-5 pg.kg body weight/day reported in several countries. A heretofore unrecognized health risk was represented by the presence of PCDDs in cigarette smoke.

Chromatography↗

PubMedDate not supplied

Treatment of hypertension in hemodialysis patients with nifedipine.

The hemodynamic effects of nifedipine were studied in nine patients with acute or chronic renal failure undergoing hemodialysis. Arterial blood pressure was lowered within 15 minutes of oral administration of nifedipine 10 mg. Mean arterial pressure and total systemic peripheral resistance were significantly decreased, whereas cardiac index and heart rate revealed slight but statistically insignificant changes. Changes in pulmonary artery diastolic pressure and mean right atrial pressure which were closely related to cardiac preload were not significant. However, the antihypertensive effect was enhanced in patients with lower pretreatment preload. Results show that oral nifedipine is effective in rapidly reducing blood pressure during or following hemodialysis.

Adult↗

PubMedDate not supplied

Impaired neutralizing capacity of duodenal mucosa following luminal acidification in recurrent duodenal ulcer.

To investigate the role of the mucus-bicarbonate barrier in the prevention of duodenal ulcer recurrence, duodenal mucosal neutralizing capacity and mucosal prostaglandin (PG) synthesis were examined in 5 normal controls (NC) and 12 duodenal ulcer (DU) patients. DU patients were divided into non-recurrent (NR,7) and recurrent (R,5) groups based on endoscopic follow-up study. The recovery time (RT) was significantly longer and the mucosal PGE2 synthesis was significantly lower in R than in NC and NR groups. There was a proportional correlation between mucosal PG synthesis and RT in DU These results indicate that impaired neutralizing capacity caused by reduced endogenous PG synthesis in duodenal mucosa may contribute to recurrence of DU.

Adult↗

PubMedDate not supplied

Predetermining postoperative hepatic function for hepatectomies.

To perform major resections safely in liver cancer operations, we have developed a reliable preoperative method to estimate postoperative liver function. We first conducted a series of studies using dogs to determine the various correlations between the volume of the remaining liver and postresectional hepatic function. We calculated Indocyaningreen (ICG) plasma disappearance and retention rates 15 minutes after intravenous injection of ICG at 0.5 mg/kg and found a 1:1 ratio, thus: ICG(K) postop. = ICG(K) preop. x functional remaining rate. This was applicable in our study of dogs with normal livers; in clinical cases complicated by liver cirrhosis and cancer, however, the functional rate of the remaining liver cannot be calculated only by the volumetric ratio of the whole liver and the remaining part. In clinical cases it must also be calculated by using hepatic vein catheterization and by measuring the ICG extraction rate of each segment of the part to be resected and the part to remain. By using this segmental liver function test, the postoperative hepatic function can be estimated accurately before the operation, thus enabling the surgeon to perform major hepatectomies safely and efficiently.

Animals↗