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Biomedical subjects

H Sekimoto

Publications and source records attributed to H Sekimoto.

At least 37 records · Page 2Linked to original sources
PubMed1994

The enzymatic formation of 1 alpha,25-dihydroxyvitamin D3 from 25-hydroxyvitamin D3 in the liver of fetal rats.

We have confirmed the existence of 25-hydroxyvitamin D3 (25-OH-D3)-1 alpha-hydroxylase in the liver of fetal rats, in addition to that in the kidney, by in vitro experiments. The findings are similar to those in the fish liver as reported previously (Takeuchi et al., Life Sci. 32, 275-282, 1991). When [3H]-25-OH-D3 was incubated with liver homogenates of vitamin D-deficient fetal rats, a peak corresponding to [3H]-1 alpha,25-dihydroxyvitamin D3 (1,25-(OH)2D3) was observed in the profile of high-performance liquid chromatography (HPLC). The formation of the metabolite was confirmed by thermal isomerization into the pre-isomer, binding affinity to the receptor and mass fragmentography. Lineweaver-Burk plot analysis of mitochondrial 25-OH-D3-1 alpha-hydroxylase in the liver gave an apparent Km value of approximately 2 microM of 25-OH-D3 and a Vmax value of 0.2 pmol of 1,25(OH)2D3/30 min/mg protein. These findings suggest that the enzyme in the liver disappeared with the growth of the fetus and became predominant in the kidney of mature rats.

Aging↗
PubMed1992

Simultaneous cardio-cerebral ultrasonic measurement technique for assessing the interrelationship between cardiac and cerebral circulations in elderly subjects: a preliminary study.

To assess the interrelationship between the cardiac and cerebral circulations, simultaneous measurements of cardiac output (CO) and common carotid blood flow volume (CCBFV) was performed by M-mode echocardiography of the left ventricle, and quantitative ultrasonic Doppler blood flowmetry of the common carotid artery. The subjects studied were 12 healthy persons living in a home for the elderly ranging in age from 62 to 99 years. These subjects were divided into two groups: those who were in their 90s (Group I, 5 females) with a mean age of 93.6 +/- 3.5 years (mean +/- SD), and those who were in their 60s to 80s (Group II, 1 male and 6 females) with a mean age of 77.1 +/- 8.1 years. The average CO in Group I was 2.85 +/- 0.37 L/min, and 4.18 +/- 0.52 L/min in Group II. The average CCBFV was 4.74 +/- 0.64 dl/min in Group I, and 4.44 +/- 1.01 dl/min in Group II. The ratio of CCBFV to CO was 16.6 +/- 1.32% in Group I, and 10.6 +/- 1.45% in group II. Good linear correlations of y = 1.44x +0.65 (r = 0.82) in Group I and y = 1.58x - 2.15 (r = 0.81, p less than 0.05) in Group II were observed between CO (x) and CCBFV (y). No such close correlations were observed between CCBFV and other indices of left ventricular function such as circumferential fiber shortening or fractional shortening of the diameter of the left ventricle (r less than or equal to 0.56, p greater than 0.05).(ABSTRACT TRUNCATED AT 250 WORDS)

Aged↗
PubMed1991

[Echocardiographic assessment of the effect of aging on the diastolic and systolic functions of the left ventricle].

The effects of aging on the diastolic and systolic functions of the left ventricle were studied by echocardiography as follows. (1). Maximum velocity of circumferential fiber lengthening (negative peak Vcf) and shortening (peak Vcf) was assessed by digital M-mode echocardiography in 20 healthy young subjects and 26 healthy elderly subjects. The mean value of negative peak Vcf (-cir/sec) was -3.87 +/- 0.85 in the 20's. -4.48 +/- 1.14 in the 30's, -3.71 +/- 1.21 in the 40's, -2.70 +/- 0.90 in the 60's, -2.57 +/- 0.64 in the 70's, -2.33 +/- 0.77 in the 80's and -2.57 +/- 0.65 in the 90's showing significant difference among young and elderly groups (p less than 0.05- p less than 0.005). The mean value of peak Vcf showed no significant difference among young and elderly groups except for the group in the 30's which showed significant (p less than 0.05) difference between other groups. (2). Indices of the left ventricular systolic and diastolic functions were calculated by standard M-mode echocardiographic technique in 227 healthy subjects from 5 to 94 years in age by dividing them into 3 young groups and 4 elderly groups. As for the left ventricular internal diameters a tendency of increase was observed in the end diastolic diameter of the left ventricle in accordance with ageing. Fractional shortening of the left ventricular diameter which ranged from 36.2% to 36.7% in the 3 young groups and 36.9 to 40.3% in the 4 elderly groups and cardiac output showed no age dependent decrease.(ABSTRACT TRUNCATED AT 250 WORDS)

Adolescent↗
PubMed1991

Osteopenic changes in high sugar diet-induced diabetic rabbits (HSDD-R).

Rabbits maintained on a persistent high sugar diet eventually develop diabetes mellitus with a marked decline in glucose tolerance, but no studies have been conducted on the associated bone changes in these high sugar diet-induced diabetic rabbits (HSDD-R). Radiographs have revealed a significant thinning of the femoral cortex of these rabbits with markedly decreased bone mass. Scanning electron microscopy of the femoral cortex using the freeze-fractured technique have revealed the loss of a typical structure of Haversian canals and the surrounding concentric and radiating lamellar bones and also the loss of fibrous components in the section. The border created by the cement line was indistinct and resulted in amorphous changes. Formation of heterogenous bundles of fibrous components different from the usual reticular structure was seen within the subendothelial space of the Haversian canals. These results indicate that qualitative changes can apparently occur in the bone along with the development of osteopenia in the diabetic state.

Animals↗
PubMed1991

[Pathophysiological study of corona radiata infarcts by clinically available diagnostic methods].

The authors evaluated 18 patients who presented with corona radiata infarction, one of the 'water-shed infarctions', on CT and/or MRI to determine its etiology and pathophysiology using cerebral angiography, single-photon emission computed tomography (SPECT), and tests of hemostatic function including hematocrit, platelet aggregation and adhesiveness. On angiography, 8 of these 18 patients had ulcerative lesions in the common carotid artery bifurcation with or without minimal stenosis and exhibited no or a minimal area of hypoperfusion localized to the corona radiata on SPECT. In these, microembolism from the lesions at the common carotid bifurcation seemed play an important role in the genesis of corona radiata infarction. In 7 of the remaining 10 patients, cerebral angiography showed occlusive lesions of the internal carotid artery around its origin in 3, more than 90% stenosis of the internal carotid artery in 1, severe stenosis of the M1 segment of the middle cerebral artery in 2, and M1 occlusion in 1. In 5 of these 7, SPECT demonstrated a larger area of hypoperfusion than the corona radiata in the involved hemisphere. In the remaining 2, SPECT demonstrated a hypoperfusion area localized to the corona radiata. In all 7, the hematocrit was elevated. A collateral blood supply was visualized in 5 of 7 on cerebral angiography. In these 7 patients, hemodynamic disturbance was considered to contribute to the pathogenesis of infarction in the corona radiata. In the final three patients, cerebral angiography showed significant occlusive lesions in the main trunk of the cerebral arteries.(ABSTRACT TRUNCATED AT 250 WORDS)

Aged↗
PubMed1990

[The application of the glycemic index to the treatment of diabetes mellitus in the elderly].

For the application of the glycemic index (GI) to the therapy of diabetes mellitus (DM) in the elderly, effects of aging and foods were studied in 3 groups of subjects, conducting 3 oral tests of equal calories, namely, glucose, white bread (high-GI meal) and kidney beans (low-GI meal). Group I: healthy adults (N = 7), Group II: elderly non-DM (N = 7), Group III: elderly DM (N = 7). No significant changes with age could be found in blood glucose or GI. However, ingestion of a low-GI meal revealed excellent inhibitory effects upon postprandial glycemic elevation in the elderly diabetics. This implies the clinical usefulness of a low-GI meal (beans) for postprandial glycemic regulation in elderly diabetes mellitus.

Adult↗
PubMed1990

[Echocardiographic assessment of mitral annular calcification in hypertrophic cardiomyopathy with asymmetric septal hypertrophy and healthy elderly cases].

The prevalence and degree of mitral annular calcification (MAC) in elderly cases of hypertrophic cardiomyopathy with asymmetric septal hypertrophy (ASHCM) were studied in comparison with healthy elderly and chronic hypertensive elderly with concentric left ventricular hypertrophy (HT + LVH) by echocardiography. In seven elderly patients with ASHCM (mean age 77.3 +/- 8.1 years) severe MAC was observed in all cases (1 male and 6 females) and systolic anterior motion of the mitral valve (SAM) was present in 3 cases, incomplete in 2 and absent in 2 cases. Of 57 healthy elderly with a mean age of 78.8 +/- 8.8 years, 8 subjects (1 male and 7 females, 14%) showed MAC. The prevalence of MAC was 0% in the sixties, 14% in the seventies, 16% in the eighties and 29% in the nineties. MAC was severe in four subjects above eighty years old. In 3 cases with HT + LVH with a mean age of 72.3 +/- 4.7 years no MAC was observed and SAM was present in one, partially observed in one and absent in one case, respectively. Serum calcium (Ca) and phosphorus (P), reported to be related with the formation of MAC, and fasting blood sugar level (FBS) were evaluated. In healthy elderly with MAC, serum Ca was 8.78 +/- 0.46 mg/dl, P 3.55 +/- 0.37 mg/dl and FBS 97.75 +/- 29.01 mg/dl, P 3.55 +/- 0.37 mg/dl and FBS 97.75 +/- 29.01 mg/dl.(ABSTRACT TRUNCATED AT 250 WORDS)

Aged↗
PubMed1986

Evaluation of the effects of photoradiation therapy on brain tumors with in vivo P-31 MR spectroscopy.

In vivo phosphorus-31 magnetic resonance (MR) spectra were obtained by a surface coil method from rat glioma tissue inoculated subcutaneously in CD Fisher rats, and the effects of photoradiation therapy on tumors were evaluated by sequentially observing spectral changes. In the control group, the nucleoside triphosphate (NTP) and phosphomonoester peaks were large, the phosphocreatine peak was small, and the inorganic phosphate (Pi) peak was intermediate. In all eight cases in the group in which a dose of 10 mg/kg of hematoporphyrin derivatives (HpD) was given before photoirradiation, NTP peaks decreased, and the Pi peak increased remarkably within 1 hour after the 60-minute white-light irradiation. Spectral changes were observed before histologic changes were apparent. Histologic examinations 3 days after irradiation showed extensive necrosis in the tumor tissue. With preinjection of 5 mg/kg HpD, three of the eight cases showed spectrum changes after the irradiation. No spectrum changes were observed in the group with preinjection of 2.5 mg/kg. In vivo P-31 MR spectra measurements are useful not only to investigate the energy metabolism of tumor tissue in vivo but also to evaluate the effects of photoradiation therapy on tumors.

Animals↗
PubMed1983

Changes of serum total cholesterol and triglyceride levels in normal subjects in Japan in the past twenty years. Research committee on familial hyperlipidemia in Japan.

Serum lipid levels of 10,977 normal Japanese subjects in 1980 were determined by a joint study of 14 institutions, specializing in lipid research, located in 9 districts of Japan. The data obtained were compared with those in 1960 and 1970. Total cholesterol (TC) levels in 1980 increased with age except for the 1st decade and reached maximum (205 mg/dl) at the 7th decade. The mean value in any age was higher than that of 20 years ago by 10-15 mg/dl. Triglyceride (TG) levels also increased with age and reached maximum (130 mg/dl) at the 7th decade. The mean values of subjects over the 5th decade were higher than those of 10 years ago by 10-20 mg/dl. In contrast with TC and TG, HDL-cholesterol levels were highest at the 1st decade and declined gradually with age. TC and TG levels of younger age (1st to 3rd decade) were equal to or even higher than those of Americans in 1972-76. It was concluded that serum lipid levels of Japanese have increased in the past 20 years and approached to the levels of Europeans and Americans.

Adolescent↗