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M Shigemura

Publications and source records attributed to M Shigemura.

10 recordsLinked to original sources
PubMed1993

Octanol/water partition coefficient of ortho-substituted aromatic solutes.

The partition coefficient (P) of some mono- and di-ortho-substituted aromatic compounds was measured in a 1-octanol/water system. For each series of compounds with the same functional group, the pi value (the difference in the log P value between the substituted and unsubstituted compound) was analyzed on the same basis as the values of meta- and para-substituted isomers by an extended Hammett-Taft procedure. In the procedure, we considered the intramolecular electronic and steric effects, operating between substituents and governing the relative hydrogen-bonding solvation with partitioning solvents for solutes in which internal hydrogen-bond formation can be ignored. The pi value for mono- and di-ortho-substituted derivatives was adequately included in the correlation equation for the values of the meta- and para-substituted derivatives in each series. The effect of di-ortho substituents on partition behaviors could be roughly expressed by the sum of the effects of the 2- and 6-position substituents.

Hydrocarbons↗
PubMed1990

[Comparison of cardiac output between in DDD and in VVI by pulsed Doppler echocardiographic method (correction with Swan-Ganz catheter method)].

Difference of cardiac output and stroke volume between that in DDD and that in VVI was studied by pulsed Doppler echocardiography at different pacing rates. Moreover, to evaluate the usefulness of the method by pulsed Doppler echocardiography, cardiac output by the Swan-Ganz catheter method was measured and compared. Fourteen patients age 37-83 years (mean 65 years) with sick sinus syndrome and implanted multiprogrammable dual chamber pacemakers were studied. Cardiac output was measured as the product of the echocardiographically determined cross sectional area of the aortic anulus and the Doppler-determined mean velocity of left ventricular outflow over systole. Cardiac output was greater in DDD with atrial kick than in VVI at each pacing rate, and increased with elevation of the rate, but it was smaller at 120 PPM than at 110 PPM in DDD. Stroke volume was greater in DDD than in VVI at each pacing rate, and maximum volume was at 60 PPM in both modes. The data by pulsed Doppler echocardiography and by Swan-Ganz catheter method have high correlation. Besides being related with pulse rate, these results may be related with such things as myocardial contractility, preload and afterload. For example, the tension of autonomic nervous system, the changing of venous return volume, the disease of arteriosclerosis and old myocardial infarction, temperature, blood viscosity and so on. We will continue the study considering these factors.

Adult↗
PubMed1985

[Clinico-pathological studies on small obese mice occurring in C57BL/6J-ob/ob mice].

Eight small obese mice, 10 to 79 weeks of age, which occurred in C57BL/6J obese mice, were examined clinico-pathologically. These mice were characterized by small-sized obesity, and showed hyperglycemia without hyperinsulinemia and glucosuria without ketonurina throughout their life span. Morphologically, neither hypertrophy nor hyperplasia were found in the islets of Langerhans. There were an increase of A cells and a decrease of B cells in their islets. In the kidney, thickening of mesangial matrix in glomeruli and deposition of glycogen in the nucleus of epithelial cells of the distal tubules were seen. These findings suggest that the small obese mice are an obese-diabetic animal of different type from the usual obese mice (C57BL/6J-ob/ob). The mechanism for development of this condition was unknown.

Animals↗
PubMed1985

[Pulmonary calcification in C3H mice].

C3H mice including aged retired breeding females, aged virginal females, young virginal females and young males were examined for the incidence and severity of pulmonary calcification. Pulmonary calcification appeared in aged females, but not in young mice of either sex, and the lesions in aged breeders were more severe and frequent than in aged virgins. These results indicate that spontaneous pulmonary calcification is observed in aged females of the C3H strain. The findings of increased incidence and severity of pulmonary lesions in aged breeders suggest that pregnancy, delivery and lactation are important enhancing factors. Calcified lesions were also observed in kidney, heart, brain, ovary, choroid plexus, cornea and artery in the animals examined.

Aging↗
PubMed1981

Characteristics of 106 spontaneous mammary tumours appearing in Sprague-Dawley female rats.

Pathological studies were undertaken on 106 mammary tumours (89 benign, 17 malignant) appearing spontaneously in 95 normal female Sprague-Dawley rats which were killed at Day 756. The benign tumours comprised those with a predominant acinar hyperplasia and those with adenomatous or fibroadenomatous pattern. No significant differences were found histochemically between the acinar cells of the benign tumours and of the lactating gland, except that the amount of fibrous interstitial connective tissue was larger in the former. 3H- or 35S-glycosaminoglycan synthesis by the benign tumours was found to be much higher. The prolactin value in the plasma of the benign-tumour-bearing rats was about 27 times that of 6-month-old virgin rats, and similar to that of rats on the 7th day post partum. Carcinomatous proliferation of tubuloacinar cells could be seen in 5 of the 89 benign tumours. The incidence of benign tumours increases with the age of the rats.

Animals↗