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Biomedical subjects

T Suzuki

Publications and source records attributed to T Suzuki.

At least 19 recordsLinked to original sources
PubMed2025

Impact of Chewing Behavior Change on Cognition and Cerebral Hemodynamics.

BACKGROUND: Impaired chewing ability is a recognized risk factor for cognitive decline in older adults, potentially due to reduced neural stimulation in cognition-related brain regions. While short-term studies have demonstrated transient increases in neural activity from chewing, the sustained cognitive and neurophysiological effects of encouraging thorough chewing habits in daily life remain unclear. OBJECTIVE: This randomized controlled trial investigated whether promoting thorough chewing during meals could improve cognitive function and cerebral hemodynamics in older adults. METHODS: Fifty participants aged 65 y or older were randomly assigned to either a 1-mo intervention group, which used a wearable device to monitor and increase chewing strokes during meals, or a control group that maintained usual chewing habits. Chewing behavior, cognitive performance (including memory and executive function via the color Stroop test), and cerebral hemodynamics in the dorsolateral prefrontal cortex (DLPFC) were measured at baseline and after 1 mo. Statistical analyses included t tests, chi-square tests, 2-way analysis of variance with post hoc tests, Pearson correlations, and generalized linear models to evaluate group differences and associations between chewing and cognitive outcomes. RESULTS: Significant time-by-group interactions were observed for memory, F(1, 48) = 6.24, P = 0.043, and hemodynamic responses in the left DLPFC, F(1, 48) = 6.19, P = 0.013. The intervention group showed increased chewing frequency (P = 0.017), improved memory performance, and reduced left DLPFC responses compared with controls. Chewing frequency was positively correlated with Stroop test scores (r = 0.53, P = 0.010) and negatively with hemodynamic changes in the left DLPFC (r = -0.30, P = 0.040). Although improvements in other cognitive outcomes and hemodynamic measures favored the intervention group, these differences did not reach statistical significance. CONCLUSIONS: Promoting intentional chewing habits for 1 mo may enhance memory-related cognitive performance and neural efficiency in the DLPFC during working memory tasks in older adults. This nonpharmacologic, low-burden strategy warrants further research with longer interventions to support cognitive health and dementia prevention. TRIAL REGISTRATION ID: UMIN000044280Knowledge Transfer Statement:This study demonstrates that promoting thorough chewing habits in older adults can improve memory and enhance neural efficiency in the brain. Encouraging intentional mastication is a simple, nonpharmacologic approach that may help maintain cognitive health and prevent dementia, providing a practical strategy for clinicians and policymakers to support healthy aging.

Humans↗
PubMed1979

Periarteritis nodosa in spontaneously hypertensive rats -- incidence and distribution.

SHR rats (Nihon Rat Inc.) were used to study spontaneous arterial lesions morphologically resembling human periarteritis nodosa (PN). Male SHR rats (159) developed PN in 76.1%, whereas females (39) in 10.3% during a period of 2 to 15 months of age. The frequency of PN in male SHR rats tended to increase with ageing and reached 100% at 9 months of age. PN lesions were widely distributed with only the lungs, brain and aorta being spared. PN in females was restricted to the tongue, parametrium and mesenterium. Male SHR rats with hypertension of more than 180 mm Hg showed PN in 81.7%, whereas in females with the same hypertension PN was found in only 17.4%. Although there was apparent sex difference in the incidence and background of hypertension, male SHR rats might be a useful animal model of human PN.

Age Factors↗
PubMed1979

Effects of dietary cadmium on rhesus monkeys.

Ten male rhesus monkeys, each weighing 3.5 kg, were divided into four groups of 3, 3, 2, and 2, and were fed daily with 100 g pelleted food containing 300, 30, 3, and 0 ppm cadmium, respectively. Urine samples were collected every 2 weeks and blood samples every 4 weeks. One monkey each of the 300 and 30 ppm groups was autopsied for pathological examination and tissue cadmium determination at the week 24 of the experiment; the remaining 8 animals were killed after 55 weeks. The lowest exposed group (3 ppm) did not show any specific biological response to cadmium over a period of 55 weeks. In the 30 ppm group, no significant changes were observed for up to 24 weeks, although cadmium concentration in the renal cortex and urine at 24 weeks were 300 mug/g wet weight and 18 mug/l., respectively. Plasma urea nitrogen and urine protein (quantitative determination) increased after 30 and 36 weeks. At 55 weeks of the experiment, qualitative tests were negative for low molecular weight proteinuria and glycosuria, and the results remained normal for renal and liver function tests and blood analysis, although cadmium concentrations in the renal cortex of two monkeys were 460 and 730 mug/g wet weight and those in the liver were 110 and 160 mug/g wet weight, respectively. In the highest exposure group (300 ppm), urine cadmium increased to 250 mug/l. by 11 weeks, and urine retinol-binding protein, plasma GOT, GPT, and LDH increased after 12 weeks. Proteinuria (quantitative determination), glycosuria, aminoaciduria (panaminoaciduria), and erythrocytopenia were observed after 16 weeks, when urine cadmium was 500-900 mug/l. Hypohemoglobinopathy and proteinuria (qualitative determination) were observed after 20 and 24 weeks, while cadmium concentrations in the renal cortex and the liver were 760 and 430 mug/g wet weight at 24 weeks, respectively. Slightly depressed tubular reabsorption of phosphate, increased urine beta(2)-microglobulin, increased plasma urea nitrogen, and increased plasma alpha(2)-globulin fraction (electrophoresis) were observed between 28 and 30 weeks of the experiment. Creatinine clearance and plasma cholinesterase decreased after 47 and 54 weeks, respectively. Cadmium concentrations in the renal cortex and the liver of two monkeys at 55 weeks were 350 and 580 mug/g wet weight and 410 and 630 mug/g wet weight, respectively. Pathological examinations revealed denaturation, destruction, and regeneration of the epithelial cells in renal proximal tubules, but no pathological changes in osseous tissues. Critical cadmium concentration in the renal cortex was estimated to be 380 mug/g wet weight for low molecular weight proteinuria and 470 mug/g wet weight for proteinuria, glycosuria, and aminoaciduria. Critical concentration in the liver was also estimated to be 210 mug/g wet weight. The apparent biological half-time of cadmium in monkeys at autopsied stage was calculated to be 0.66, 6.4, 5.2, and 22.4 years for the 300, 30, 3, and 0 ppm groups, respectively.

Animals↗
PubMed1978

Effects of Kö 1366 on the hemodynamics of the normotensive and hypertensive elderly subjects.

The hemodynamic effects of a new adrenergic beta-receptor blocking agent, Kö 1366 were investigated in normotensive and hypertensive elderly subjects. This study, in its important part, was carried out to clarify whether the intrinsic sympathomimetic activity of Kö 1366 modified the hemodynamic changes due to beta-adrenergic blocking action or not. Hemodynamic changes elicited by intravenously administered Kö 1366 (0.05 mg/Kg) were correlated with age, cardiac index, and electrocardiographic findings, respectively. With reference to age in normotensive subjects, Kö 1366 caused no significant differences in rate of changes of various hemodynamic items between 3 age groups. Normotensive elderly subjects were divided into 3 groups according to cardic index. Cardiac index decreased greatly in high cardiac index group, slightly in normal cardiac index group, whereas it increased greatly in low cardiac index group. Stroke volume index showed the same tendency as cardiac index. Hypertensive elderly subjects were, also divided into 2 groups according to cardiac index. Again, cardiac index decreased in higher cardiac index group, while it increased in lower cardiac index group, though a statistical evaluation showed only a tendency of significant difference between 2 groups. In the next, hypertensive elderly subjects were divided into 2 groups according to electrocardiographic findings of left ventricular hypertrophy. Cardiac index decreased in the subjects without electrocardiographic changes, while it increased in the subjects with electrocardiographic changes. Stroke volume index of both groups increased: a greater increase in the subjects with electrocardiographic changes and a tendency of significant difference between 2 groups was recognized. These results suggested that Kö 1366 exhibited the intrinsic symathomimetic activity on the inotropism in the hearts with depressed contractile function of both normotensive and hypertensive subjects, thereby canceling the negative chronotropic action of this agent. This could be a more advantageous point of Kö 1366 in the treatment of elderly subjects with cardiac diseases than other agents without the intrinsic sympathomimetic activity.

Adrenergic beta-Antagonists↗
PubMed1978

Abnormal serum immunoglobulin levels in Down's syndrome patients.

Serum immunoglobulin levels were measured in 20 patients with Down's syndrome and 16 mentally retarded cerebral palsy control patients. Significant elevation of IgG and IgD levels were found in the Down's syndrome as compared with the control patients. Serum IgD level in Down's syndrome individuals significantly decreased with increasing age. Serum IgA level was significantly elevated in older Down's syndrome patients but showed no change in younger Down's syndrome patients. Serum IgM and IgE levels were slightly elevated in Down's syndrome patients, but these differences were not significant. The elevated immunoglobulin levels in Down's syndrome individuals seem to be a response to increased frequency of infection.

Adolescent↗
PubMed1978

[Quarantine and health control of the squirrel monkey (Saimiri sciureus) (author's transl)].

A total of two hundreds and seventy squirrel monkeys (Saimiri sciureus) of both sexes were imported from South America through an animal dealer of the U. S. A. in eight lots from May, 1973 to July, 1974. They were investigated for the presence of the parasites for a maximum of fifteen months including nine weeks of quarantine period from the time of import. The mortality rate before or immediately after arrival at our laboratory reached 56.7% in the first two lots. This, however, could be reduced later to 4.8% by improving some conditions of transportation. Bacteriological surveys revealed no shigella or salmonella infections during the quarantine period. No tuberculin positive reactors were also detected. Filarial infestations seemed to be common in this species; about 45.5% had adult worms in the peritoneal cavity and about 65% harbored microfilaria in the peripheral blood. Acanthocephla was also found in a high rate in the lower alimentary tracts. It has been suggested that the worms disappear in fifteen months by keeping animals in the intermediate host-free circumstances. The sarcocyst was found in the femoral muscle of 7 (18.9%) of 37 animals examined histologically.

Acanthocephala↗