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Biomedical subjects

M Kihara

Publications and source records attributed to M Kihara.

At least 289 records · Page 16Linked to original sources
PubMed1982

Induction of choline kinase by polycyclic aromatic hydrocarbons in rat liver. I. A comparison of choline kinases from normal and 3-methylcholanthrene-induced rat liver cytosol.

Choline kinase in rat liver has been shown to be induced up to 2-fold by the administration of polycyclic aromatic hydrocarbon carcinogens such as 3-methylcholanthrene and 3,4-benzo[a]pyrene (Ishidate, K., Tsuruoka, M. and Nakazawa, Y., (1980) Biochem. Biophys. Res. Commun. 96, 946-952). In order to characterize the nature of choline kinase induction by these carcinogens, the 3-methylcholanthrene-induced form as well as the normal form of choline kinase were partially purified from rat liver cytosol through acid treatment, (NH4)2SO4 precipitation and DEAE-cellulose column chromatography with linear KCl-gradient elution, and the catalytic properties were compared between the two preparations. Both enzyme activities were purified about 17-fold with a yield of 50% through the purification steps and there appeared no detectable difference in the elution pattern from either DEAE-cellulose column or Sephadex G-200 gel filtration. On the other hand, some differences were observed in catalytic properties between the two enzyme preparations; (1) the induced form showed a higher apparent Km value for choline (0.19 mM) when compared to the normal form (0.11 mM) and (2) the addition of polyamines caused a considerable increase in the maximum reaction velocity for the normal form whereas no remarkable change for the induced form, when the activities were plotted as a function of choline concentration. The overall results suggest that the 3-methylcholanthrene-induced form of choline kinase in rat liver could be different from the normal form, or that there exist several isoenzymes of choline kinase in rat liver, and one or some of them are inducible by the administration of polycyclic aromatic hydrocarbons.

Adenosine Triphosphate↗
PubMed1982

Isolated adrenocorticotropic hormone (ACTH) deficiency.

The case to be reported is that of a 72-year-old woman with isolated adrenocorticotropic hormone (ACTH) deficiency, who complained of anorexia and generalized malaise. The secretions of human growth hormone (HGH), prolactin (PRL), luteinizing hormone (LH), follicle stimulating hormone (FSH), and thyroid stimulating hormone (TSH) were all within normal limit. In spite of the extremely low level of cortisol, the plasma level of ACTH would not rise sufficiently, but a marked response of cortisol to ACTH stimulation was recognized. The postmortem examination revealed a decrease in basophilic or PAS-positive cells of the anterior pituitary gland which also showed a selective loss of ACTH-secreting cells over immunohistochemical study. Electron microscope could easily visualize somatotroph, mammotroph, thyrotroph, FSH- and LH-gonadtroph, but corticotroph was difficult to be discerned. Adrenocortical cells demonstrated atrophy and degeneration, for which the zona fasciculata and zona reticularis were narrowed. The zona glomerulosa was slightly enlarged in width.

Adrenal Glands↗
PubMed1982

Symptomatological classification in the development of stroke in stroke-prone spontaneously hypertensive rats.

The developmental course of cerebrovascular diseases was examined by comparative neurological and pathological studies in stroke-prone SHR (SHRSP) which died spontaneously or were sacrificed. Behavioral status during their life span could be simply divided into 4 patterns, i.e., "no abnormalities", "irritable", "lethergic" and "akinetic" named Grades 0, I, II and III, respectively (Yamori's Classification). Grades I, II and III of behavioral status corresponded well to symptomato-pathoanatomically divided 3 stages (relating to brain edema), i.e., Stages I, II and III, respectively.

Animals↗
PubMed1982

Dietary risk factors of stroke and hypertension in Japan -- Part 1: Methodological assessment of urinalysis for dietary salt and protein intakes.

In our attempt to design a method which would be more reliable than dietary survey interviews when estimating salt and protein intakes in a population survey, a urinalysis-related study was done on volunteers. Urinary sodium (Na), urea nitrogen (UN) and inorganic sulfate (SO4), all indices of dietary salt, protein and sulfoamino acids, respectively, were confirmed to reflect the nutritional condition. Interaction between salt and protein was not observed at least at the dietary levels used in the present study (for salt, 0.33 and 0.1 g/kg body weight/day; for protein, 1.6 and 0.7 g/kg body weight/day). Excretion of components was delayed several days or more after dietary ingestion, and nutritional estimation by urinalysis, therefore, may not be so much affected by daily variables in the diet intake. Further, partial urine samples proved to have a highly significant correlation with 24-hour (hr) urine, as for urinary Na, potassium (K), SO4, UN and their creatinine (Cr) ratios, thus indicating the availability of partial urine samples as substitutes for 24-hr urine specimens. Thus, urinalysis is a more readily facilitated, more scientific and more quantitative method for epidemiological nutritional surveys.

Adult↗
PubMed1982

Dietary risk factors of stroke and hypertension in Japan -- Part 2: Validity of urinalysis for dietary salt and protein intakes under a field condition.

Utility of urinalysis as a method for estimating dietary salt and protein intakes was examined in volunteers from farming and fishing villages in Japan and the data was compared to findings in a survey on diets. We found that partial urine samples and even a fasting single spot urine in the a.m. could serve as valid substitutes for 24-hour (hr) urine collections. Further, significant correlations were obtained between levels of salt in the diet estimated by survey interviews and urinary sodium (Na) and between interview-estimated dietary total or animal protein and urinary inorganic sulfate (SO4). In comparative studies between farming and fishing villages, almost the same findings, higher salt in a farming village and higher animal protein in a fishing village, were obtained in the urinalysis and the survey on diets. These findings clearly indicate that urinalysis, as a method for estimating dietary salt and protein intake in population surveys, has distinct advantages.

Adult↗
PubMed1982

Dietary risk factors of stroke and hypertension in Japan -- Part 3: Comparative study on risk factors between farming and fishing villages in japan.

General medical examinations were performed in two rural areas of Shimane Prefecture in Japan, one was a farming village and the other a fishing village where incidences of death due to stroke differed, higher in the former and lower in the latter. Comparisons were made on salt and protein intake by analyzing the fasting single spot urine collected in the morning and by blood tests. Urine samples were analyzed for sodium (Na), potassium (K), urea nitrogen (UN), inorganic sulfate (SO4) and creatinine (Cr) and blood samples for cholesterol (Chl), triglyceride (TG), hematocrit (Ht) and hemoglobin (Hb). Blood pressure, Na/Cr, Na/K and Ht were higher in the farming village and K/Cr, UN/Cr, SO4/Cr, SO4/UN, Chl and TG were higher in the fishing village. These findings indicate the higher salt intake and lower intake of K, animal protein and fat in the farming village. This typical dietary pattern of the Japanese may explain the higher incidence of hypertension and stroke in the farming village.

Adult↗
PubMed1981

Mechanisms of structural vascular changes in genetic hypertension: analyses on cultured vascular smooth muscle cells from spontaneously hypertensive rats.

1. The basic mechanism underlying the structural vascular changes occurring in hypertension was studied in cultured aortic smooth muscle cells (SMC) obtained by an explant method from spontaneously hypertensive rats (SHR) and stroke-prone SHR (SHRSP) and compared with that in normotensive Wistar--Kyoto (WKY) rats. 2. The growth rate of SMC from SHR and SHRSP at the age of 2.5--11 months was greater than that of SMC from WKY rats even after repeated passages. 3. [3H]Thymidine and [14C]leucine incorporation, and ornithine decarboxylase (ODC) activity of SMC were increased in SHR and SHRSP in comparison with WKY rats. 4. The application of isoprenaline but not noradrenaline to the culture media increased ODC activity acutely in SMC from WKY rats and this increase was blocked by propranolol. 5. These results indicate that SMC from SHR and SHRSP are more prone to proliferate than those from WKY rats and that a beta-adrenergic neurohumoral mechanism accelerates SMC growth independently of blood pressure.

Animals↗
PubMed1981

Cytoplasmic pH mediates pH taxis and weak-acid repellent taxis of bacteria.

Bacteria migrate away from an acid pH and from a number of chemicals, including organic acids such as acetate; the basis for detection of these environmental cues has not been demonstrated. Membrane-permeant weak acids caused prolonged tumbling when added to Salmonella sp. or Escherichia coli cells at pH 5.5. Tethered Salmonella cells went from a prestimulus behavior of 14% clockwise rotation to 80% clockwise rotation when 40 mM acetate was added and remained this way for more than 30 min. A low external pH in the absence of weak acid did not markedly affect steady-state tumbling frequency. Among the weak acids tested, the rank for acidity (salicylate greater than benzoate greater than acetate greater than 5,5-dimethyl-2,4-oxazolidinedione) was the same as the rank for the ability to collapse the transmembrane pH gradient and to cause tumbling. At pH 7.0, the tumbling responses caused by the weak acids were much briefer. Indole, a non-weak-acid repellent, did not cause prolonged tumbling at low pH. Two chemotaxis mutants (a Salmonella mutant defective in the chemotaxis methylesterase and an E. coli mutant defective in the methyl-accepting protein in MCP I) showed inverse responses of enhanced counterclockwise rotation in the first 1 min after acetate addition. The latter mutant had been found previously to be defective in the sensing of gradients of extracellular pH and (at neutral pH) of acetate. We conclude (i) that taxes away from acid pH and membrane-permeant weak acids are both mediated by a pH-sensitive component located either in the cytoplasm or on the cytoplasmic side of the membrane, rather than by an external receptor (as in the case of the attractants), and (ii) that both of these taxes involve components of the chemotaxis methylation system, at least in the early phase of the response.

Acetates↗
PubMed1981

Genetic markers in spontaneously hypertensive rats.

Establishment of various models for hypertensive diseases such as spontaneously hypertensive rats (SHR) and stroke-prone SHR (SHRSP) clarified the importance of genetic factors in the pathogenesis of these diseases and further accelerated studies on their genetic mechanisms. Although various biochemical abnormalities have been detected and can be used as biochemical markers in these models, they have not been always closely related to blood pressure in F2 generation obtained by cross breeding between SHR and normotensive Wistar-Kyoto rats. Recent studies indicate that biomembrane abnormalities detected in erythrocytes and other membranes of SHR and SHRSP may not only be biochemical markers but also related to the pathogenesis of hypertensive diseases.

Animals↗
PubMed1981

[Effect of Bromovincamine on noradrenaline and 5-hydroxytryptamine contents, and glucose metabolism in rat brain: analysis using spontaneously hypertensive rats (SHR) (author's transl)].

Effects of Bromovincamine (BV) on cerebral noradrenaline (NA) and 5-hydroxytryptamine (5-HT) contents, and glucose metabolism in the brain were studied using stroke-prone spontaneously hypertensive (SHR-SP), stroke-resistant spontaneously hypertensive (SHR), age-matched normotensive Wistar Kyoto (WKR) and Wistar rats. In the SHR-SP which have a low level of NA in the hypothalamus, a continuous administration of BV for 1 week induced a normalization of the hypothalamic NA content. Under the same experimental conditions, a tendency toward normalization of hypothalamic NA was also observed in SHR. 5-HT contents in the cerebellum, striatum, hypothalamus, midbrain and hippocampus of SHR showed a significant increase following a single injection of BV. Similarly, 5-HT contents in the cerebellum and cerebral cortex of Wistar, WKR and SHR showed a significant increase following a continuous administration of BV for 1 week. Both in vitro and in vivo administration of BV significantly inhibited the high concentration of K+ evoked glucose consumption in cerebral cortical slices from SHR, WKR and Wistar rats, whereas glucose consumption in cerebral cortical slices from SHR determined in the absence of high concentration of K+ increased significantly following continuous in vivo administration of BV. The present results suggest that BV may be an useful drug for improving abnormal cerebral metabolisms of NA, 5-HT and glucose.

Animals↗
PubMed1980

Epidemiological analysis on the mechanism of cigarette smoking as a risk factor in cardiovascular diseases.

To clarify the mechanism involved in the contribution of cigarette smoking to increased mortality in patients of cardiovascular diseases (CVD), blood pressure (BP), serum cholesterol (Chl), triglycerides (TG), obesity index (OI), hematocrit (Ht), hemoglobin (Hb) etc, were examined in male smokers and non-smokers among 2500 inhabitants of a farming village in Japan. Smokers were classified by age and by the number (n) of cigarettes smoked per day into mild smokers (1 smaller than or equal to n < 20), moderate smokers (20 smaller than or equal to n < 30) and heavy smokers (n larger than or equal to 30). Ht was increased with the number of cigarettes smoked and was significantly higher in heavy smokers than in non-smokers, in most all the age groups. BP, Chl, TG, OI, Hb etc, showed no significant quantitative relation to the number of cigarettes smoked. This increase in Ht in smokers may represent a risk factor in increasing the morality rate in CVD.

Adult↗