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Biomedical subjects

S Yoshimoto

Publications and source records attributed to S Yoshimoto.

At least 19 recordsLinked to original sources
PubMed1992

Effect of chromium administration on glucose tolerance in stroke-prone spontaneously hypertensive rats with streptozotocin-induced diabetes.

The present study was conducted to assess the effect of chromium (Cr) administration on glucose tolerance in insulin-dependent diabetes that accompanies hypertension. Four rat groups were used: stroke-prone spontaneously hypertensive rats (SHRSP) and normotensive Wistar Kyoto rats (WKY) with and without streptozotocin (SZ, 40 mg/kg)-induced diabetes. Each group of rats was subdivided to the Cr-dose group and the control group. The Cr-dose group, which was intraperitoneally administered Cr solution (20 micrograms trivalent chromium/kg body weight/d for 4 weeks), and the control group (saline) were studied for plasma glucose and plasma insulin during intraperitoneal glucose tolerance test (IPGTT) and insulin action by isolated adipocytes. For diabetic SHRSP showing the highest plasma glucose and lowest plasma insulin among the four groups, Cr administration led to the greatest reduction in plasma glucose without a significant effect on plasma insulin during IPGTT. For each diabetic WKY and normal SHRSP and WKY, those given Cr showed lower levels of plasma glucose with lower levels of plasma insulin than the controls. For diabetic SHRSP, glucose uptake by isolated adipocytes in the Cr-dose group was higher than that in the control group. This effect of Cr administration involved enhancement of insulin responsiveness and sensitivity, attributed to enhanced affinity of the insulin receptor. A similar tendency was observed for diabetic WKY. However, for normal SHRSP and WKY, the increase in glucose uptake due to Cr administration coincided only with enhanced insulin responsiveness.(ABSTRACT TRUNCATED AT 250 WORDS)

Animals↗
PubMed1992

Decrease in plasma GLP-1 immunoreactivity in starved rats.

To determine whether starvation affects the metabolism of glucagon-like peptide-1 (GLP-1), we measured the plasma levels of proglucagon-derived peptides and the biosynthesis and posttranslational processing of proglucagon in groups of six rats starved for 1, 3 and 5 days. The plasma levels of GLP-1 immunoreactivity (GLP-1 IR) and glucagon-like immunoreactivity (GLI) decreased during starvation reaching 79 and 56% of the respective control values by day 5 (P less than 0.05 and less than 0.01 vs control). The same is true of the plasma IRI level. The ileal contents of GLP-1 IR and GLI were 50.8 +/- 3.8 pmol/g wet weight and 161.8 +/- 13.2 pmol/g wet weight, respectively, on day 5 of starvation, which were significantly lower (P less than 0.01) than the respective values of 94.8 +/- 16.6 pmol/g wet weight and 262.7 +/- 28.1 pmol/g wet weight in control rats. However, the pancreatic contents of proglucagon-derived peptides tended to increase during starvation, although their increases were not statistically significant. No significant change in the posttranslational processing of proglucagon was detected during starvation. The decrease in the ileal proglucagon-derived peptides content was not associated with a decrease in intestinal proglucagon mRNA transcripts. These results suggested that decreased synthesis of proglucagon-derived peptides by the intestine was largely responsible for the reductions in their circulating levels in starved rats.

Analysis of Variance↗
PubMed1992

[A study of factors affecting the concentration of serum lipid peroxide in the elderly inhabitants in a rural area].

Among 16 male (mean age of 66.6 years) and 51 female (mean age of 65.3 years) inhabitants of a rural area, the concentration of serum lipid peroxide measured as malondialdehyde (MDA) by Yagi's method was analyzed by physicochemical and food intake items. The MDA level in serum showed a peak of 6.2 nmol/ml at fifties years old in females and showed constant values of 4.6 and 6.1 nmol/ml for females and males, respectively, in those aged 60 more. The MDA level significantly correlated positively to total- or LDL-cholesterol level and urinary K/Cr, thus MDA level seemed to be a risk factor of arteriosclerosis. Fruit intake significantly positively correlated to MDA level in male. The MDA level showed a significantly higher level in the group with both higher total-cholesterol and urinary K/Cr levels, than in the other groups. It is suggested that a high intake of potassium increases the MDA level in the group with higher total-cholesterol level.

Aged↗
PubMed1992

[A case of pulmonary atypical mycobacteriosis complicated with aplastic anemia, treated with surgical resection and postoperative sparfloxacin].

A few weeks after treatment with INH, RFP and SM, severe aplastic anemia developed in a 49-year-old man with pulmonary atypical mycobacteriosis due to M. kansasii. All drugs were discontinued immediately after bone marrow examination revealed severely hypoplastic marrow, but pancytopenia continued for several months. Although M. kansasii was sensitive to other drugs including CS and TH, these two drugs were also discontinued because of their respective psychiatric and hepatic adverse effects. Ofloxacin (OFLX), to which M. kansasii was sensitive, was administered without clinical improvement and complete resistance to OFLX developed after several months treatment. Right upper and middle lobectomy and S6 partial lobectomy was performed, and postoperative sparfloxacin (SPFX) administration resulted in cure of the disease. Drug sensitivity testing revealed that the organism had acquired resistance to OFLX, but was still sensitive to SPFX. Thus, SPFX appears to be an useful drug for the treatment of atypical mycobacteriosis.

Anemia, Aplastic↗
PubMed1992

[Secondary sideroblastic anemia caused by long term administration of anti-tuberculous agents including isoniazid].

A 54 year-old man, who had been treated for several years with isoniazid, was transferred to our hospital because of intractable pulmonary tuberculosis. He was given several anti-tuberculous agents including INH, CS and/or PZA for a long period of time without improvement of the pulmonary tuberculosis. After 7 years' treatment with INH, hypochromic microcytic anemia developed. Parenteral administration of iron preparation failed to improve the anemia. The bone marrow findings revealed erythroid hyperplasia and a few erythroblasts showed megaloblastic change. The bone marrow iron staining revealed increased sideroblasts of which 88% were ringed-form. INH was then discontinued and pyridoxal phosphate was administered with rapid complete improvement of the anemia. INH is well known as a causative agent for acquired secondary sideroblastic anemia, however only one case of INH-induced sideroblastic anemia has been reported in Japan. This is the second reported Japanese case of INH-induced secondary sideroblastic anemia, which appears to be a very rare condition because of genetically determined rapid acetylation of INH in Japanese.

Anemia, Sideroblastic↗
PubMed1992

[Post-gastrectomized vitamin B12 deficient anemia with marked leukoerythroblastosis and ringed sideroblasts].

A 77 year-old man, who had received total gastrectomy and splenectomy 11 years ago for gastric cancer was transferred to our hospital because of severe macrocytic anemia. He had been treated with vitamin B1, B2, C and iron preparations for several weeks. Ten days before admission numbness developed in his legs. On physical examination he appeared severely anemic. Laboratory findings revealed severe macrocytic anemia with poikilocytosis, anisocytosis, polychromasia, red cell fragmentation, Howell-Jolly bodies, Cabot rings and marked erythroblastosis (421/100 WBC). Hypersegmented neutrophils and immature granulocytes were also seen in the blood. The bone marrow picture showed marked erythroid hyperplasia, but erythroblasts revealed only slight megaloblastic changes. On bone marrow iron staining all erythroblasts were classified as type III sideroblasts and 15% of them were ringed-form. Serum vitamin B12 was low (44 pg/ml). Methylcobalamin given intramuscularly led to the rapid improvement of all hematological abnormalities including leukoerythroblastosis. Two weeks after vitamin B12 administration, ringed sideroblasts could no longer be detected in the bone marrow. Post-gastrectomy vitamin B12 deficiency anemias combined with erythroblastosis and ringed sideroblasts is a rare condition. Splenectomy is thought to play an important role in the pathogenesis of these conditions.

Aged↗
PubMed1991

Potentiating effect of NH4Cl on vasoconstriction in rat aorta.

The effect on the vasocontractile response of pretreatment with NH4Cl at a concentration (10 mM) that made almost no change in the resting tension was investigated using aortic strips from rats. NH4Cl pretreatment for 10 min significantly potentiated strip contractions induced by KCl (less than or equal to 30 mM), BAY K 8644 (0.1 microM) and phenylephrine (0.01 microM). This potentiating action of NH4Cl was eliminated in presence of nifedipine (1 microM). KCl (14.7 mM)-stimulated 45Ca uptake in rat aorta was significantly potentiated by pretreatment with NH4Cl (10 mM) for 10 min, but this NH4Cl effect was also eliminated in the presence of nifedipine. These results suggest that NH4Cl potentiates contractions induced by KCl and agonists in rat aorta by facilitating calcium influx through the nifedipine-sensitive calcium channel.

3-Pyridinecarboxylic acid, 1,4-dihydro-2,6-dimethy↗
PubMed1991

The role of cerebral microvessel endothelium in regulation of cerebral blood flow through production of endothelin-1.

We have previously reported the production of endothelin-1 (ET-1) by the cerebral microvessel endothelia and suggested an important role of ET-1 and microvessel endothelia in the regulation of local blood flow within the brain. In the present study, radioimmunoassay of ET-1 revealed that ET-1, produced by cultured cerebral microvessel endothelia grown on a filter, is released mainly to the basal side (corresponding to the basement membrane side), not to the apical side (corresponding to the vascular lumen side). This might indicate that ET-1 constricts arterioles locally at the same place where it is produced by endothelia. The present results also show that cultured cerebral microvessel endothelia produce less ET-1 under low oxygen pressure and that they produce more ET-1 under low carbon dioxide pressure. Taken together, our results may suggest that the negative feedback regulation of cerebral blood flow through oxygen and carbon dioxide pressure is mediated by ET-1 produced locally by cerebral microvessel endothelia.

Capillaries↗
PubMed1978

[Studies on circadian susceptibility rhythm to haloperidol (author's transl)].

Rats were given haloperidol in a variety of doses and time combinations and the sedation period were then measured. A clear-cut daily fluctuation in the sedative effect was observed, and the pattern of fluctuation differed depending on the dosage. In an attempt to elucidate the mechanism of this phenomenon, haloperidol was administered at two different times between which there was a significant difference in the sedation period. No difference was found. Thus it is presumed that daily fluctuation in the sedative effect of haloperidol may be ascribed not to the daily fluctuation in the levels of absorption, excretion, metabolism, or distribution of this drug, but rather to the daily fluctuation at the level of catecholamine receptors in the brain. There was a daily fluctuation in the antiapomorphine effect of haloperidol in a variety of doses and time combinations, and the pattern of fluctuation almost equaled that of the sedative effects of haloperidol. The daily fluctuation of the sedative effect is probably due to effects of circadian rhythm in brain dopamine receptors.

Animals↗