Biomedical subjects

Katsuhiko Yokoi

Publications and source records attributed to Katsuhiko Yokoi.

6 recordsLinked to original sources

PubMed2006

Effects of zinc and/or iron deficiency on rectal temperature in rats.

O'Dell et al. reported that rectal temperature was decreased by zinc deficiency in rats. However, it is not known whether a combined deficiency of zinc and iron affects rectal temperature. Forty 4-wk-old male Sprague-Dawley rats were assigned into four dietary treatment groups of 10 rats each for the 4-wk study: zinc-deficient group (4.5 mg Zn and 35 mg Fe/kg diet; -Zn), iron-deficient group (30 mg Zn/kg diet, no supplemental iron; -Fe), zinc/iron-deficient group (4.5 mg Zn/kg diet, no supplemental iron; -Zn-Fe), and control group (AIN-93G; Cont). At d 24-27, the rectal temperature was determined. The rectal temperature of the -Zn group was significantly lower than the Cont group. The rectal temperature of the -Zn-Fe group was similar to that of the Cont group, although thyroid-stimulating hormone and total thyroxin concentrations were the lowest in the -Zn-Fe group among all groups. The pattern of the plasma nitrate/nitrite concentrations across groups was similar to rectal temperature. Although observation of the rectal temperature is not conclusive, the balance between zinc and iron intake seems to determine the body temperature set point. These results suggest that the thermogenic effect of thyroid hormones is not thought to influence the paradoxical maintenance of rectal temperature in combined deficiency of zinc and iron.

Animals↗

PubMed2005

Zinc deficiency decreases plasma erythropoietin concentration in rats.

In 1985, Paterson and Bettger found hypoplastic hematopoiesis in severely zinc-deficient rats. Therefore, we investigated plasma erythropoietin concentration in zinc-deficient rats. Forty 4-wk-old male Sprague- Dawley rats were assigned into 4 dietary treatment groups of 10 for the 4-wk study: zinc-deficient group (4.5 mg zinc and 35 mg iron/kg; -Zn), iron-deficient group (30 mg zinc/kg, no supplemental iron; -Fe), zinc/ iron-deficient group (4.5 mg zinc/kg, no supplemental iron; -Zn-Fe), and control group (AIN-93G; Cont). Water intake determined at d 19 was similar among all treatment groups. At d 27-28, bioimpedance was measured. The intracellular water/extracellular water ratio was significantly increased in the -Zn group (p < 0.05). Compared to the Cont, group, the plasma erythropoietin concentration was increased by iron deficiency and decreased by zinc deficiency (p < 0.01). Hematocrit was significantly decreased in both the -Fe and -Zn-Fe groups and was significantly increased in the -Zn group (p < 0.01). Transferrin saturation in the -Fe and -Zn-Fe groups was significantly lower than the Cont group (p < 0.01), and that of the -Zn group was highest among all groups. The low plasma erythropoietin concentration might account for depressed hematopoiesis associated with zinc deficiency.

Animals↗

PubMed2003

Association between plasma zinc concentration and zinc kinetic parameters in premenopausal women.

The objective of this study was to measure relationships between plasma zinc (Zn) concentrations and Zn kinetic parameters and to measure relationships of Zn status with taste acuity, food frequency, and hair Zn in humans. The subjects were 33 premenopausal women not taking oral contraceptives and dietary supplements containing iron and Zn. Main outcomes were plasma Zn concentrations, Zn kinetic parameters based on the three-compartment mammillary model using 67Zn as a tracer, electrical taste detection thresholds, and food frequencies. Lower plasma Zn was significantly (P < 0.01) associated with smaller sizes of the central and the lesser peripheral Zn pools, faster disappearance of tracer from plasma, and higher transfer rate constants from the lesser peripheral pool to the central pool and from the central pool to the greater peripheral pool. The break points in the plasma Zn-Zn kinetics relationship were found between 9.94 and 11.5 micromol/l plasma Zn. Smaller size of the lesser peripheral pool was associated with lower frequency of beef consumption and higher frequency of bran breakfast cereal consumption. Hypozincemic women with plasma Zn <10.7 micromol/l or 700 ng/ml had decreased thresholds of electrical stimulation for gustatory nerves. Our results based on Zn kinetics support the conventional cutoff value of plasma Zn (10.7 micromol/l or 700 ng/ml) between normal and low Zn status.

Adolescent↗

PubMed2003

Nickel deficiency diminishes sperm quantity and movement in rats.

Early studies on nickel essentiality with rats and goats indicated that nickel deprivation impaired reproductive performance. Nickel also has been found to influence cyclic nucleotide gated channels (CNG); these types of channels are important in sperm physiology. Thus, two experiments were conducted to test the hypothesis that nickel deficiency affects sperm physiology in a manner consistent with nickel having an essential function related to CNG channel functions. The experiments were factorially arranged with four treatment groups of eight weanling rats in each. In experiment 1, the treatments were supplemental dietary nickel of 0 and 1 mg/kg and N(omega)-nitro-L-arginine methyl ester (L-NAME, a nitric oxide synthase inhibitor) added to the drinking water (50 mg/100 mL) the last 3 wk of an 8-wk experiment. In experiment 2, the treatments were supplemental dietary nickel at 0 and 1 mg/kg and supplemental dietary sodium chloride (NaCl) at 0 and 80 g/kg. The NaCl and L-NAME variables were included to act as stressors affecting CNG channel activity. The basal diet contained per kilogram about 27 microg of nickel and 1 g of sodium. After 8 wk in experiment 1 and 16 wk in experiment 2, urine while fasting and testes and epididymis in both experiments, and seminal vesicles and prostates in experiment 2 were harvested for analysis. Nickel deprivation significantly decreased spermatozoa motility and density in the epididymides, epididymal transit time of spermatozoa, and testes sperm production rate. Nickel deficiency also significantly decreased the weights of the seminal vesicles and prostate glands. Excessive NaCl had no effect on sperm physiology; however, it decreased prostate gland weights. The findings support the hypothesis that nickel has an essential function that possibly could affect reproductive performance in higher animals, perhaps through affecting a CNG channel function.

Animals↗

PubMed2003

Numerical methods for estimating iron requirements from population data.

The estimation of iron requirements is crucial for nutrition and food policy. The traditional methods for estimating iron requirements are balance methods based on iron intakes and excretions and factorial methods based on estimated iron absorption rates and estimated iron losses from body compartments. As an alternative, numerical methods for estimating iron requirements from population data of iron status were developed. The iron status data reported by Satoh (1991) were used in the sixth edition of Recommended Dietary Allowances for Japanese. The menstrual iron losses in Japanese premenopausal women were estimated from the literature to calculate total iron losses as the sum of basal iron losses and menstrual iron losses. The use of this alternative method is illustrated by analyzing the same population data comprising the prevalence of iron deficiency and the distribution of iron intake. The estimated average requirements were affected by the form of distribution function, the relative standard deviation of requirements, and the correlation coefficient between iron intakes and requirements. We conclude that numerical methods can be very useful for estimating iron requirements and to elucidate dietary recommendations of iron. These methods may contribute to determining requirements of other nutrients as well as iron.

Absorption↗

PubMed2002

Colorimetric determination of chloride in biological samples by using mercuric nitrate and diphenylcarbazone.

A colorimetic method is outlined for the determination of the chloride ion in biological samples (blood serum, plasma, and urine). The present method is based on the quantitative reduction of free mercuric ions by chloride ions. Chloride ions form an indissociable complex with mercuric ions. The remaining free mercuric ions form a purple complex with diphenylcarbazone with an absorption maximum at 550 nm. The reduction of color intensity at 550 nm is directly proportional to chloride concentration in the sample. The linear concentration range in the final reaction mixture was 0-100 microM with a correlation coefficient of -0.9997. The coefficient of variation for the 50 microM chloride ion in the final reaction mixture was 0.9% (n = 6). The analyzed value of chloride concentration in the human control serum Accutrol Normal (Sigma) was 101+/-4 mM (mean+/-SD, n = 12). The certified value of chloride in Accutrol Normal by Sigma is 102 mM, with a mean in the range 91-113 mM. This method was applied to the measurement of urinary chloride excretion in experimental rats. During 16-h urine collection, no food was given and rats had free access to purified water. The urinary excretion rate of chloride was 23.6+/-9.3 micromol/h (mean+/-SD, n = 8) and 126.2+/-28.0 micromol/h (n = 8) for rats fed a normal diet (2.6 g NaCl/kg diet) and a high-salt diet (82.6 g NaCl/kg diet) for 70 d prior to urine collection, respectively. This method is appropriate for low concentrations of chloride in samples or when sample volume is limiting, as in many animal studies such as metabolic urine collection from rats.

Animals↗