Biomedical subjects

K Toshida

Publications and source records attributed to K Toshida.

7 recordsLinked to original sources

PubMed1998

Influences of the accommodative stimulus and aging on the accommodative microfluctuations.

The effects of the accommodative stimulus and age on the accommodative microfluctuations were investigated in human subjects. Accommodative responses were measured by using an infrared (IR) optometer, and accommodative microfluctuations were quantified by power spectrum analysis. Two frequency bands were determined: low frequency components (< 0.5 Hz, LFC) and high frequency components (1.3 to 2.2 Hz, HFC). Among younger subjects, the changes in the HFC in response to the accommodative stimuli differed between subjects. The activity of the HFC reached a peak in the center of the accommodation range, whereas the activity of the LFC was its maximum in the presence of darkness or blur in the over-accommodation range. Smaller changes in the magnitude of the HFC were observed in older subjects. Although the LFC may be controlled neurologically, the HFC seems to arise from mechanical and elastic properties of the lens, and may be modulated by other physiological rhythmic variations.

Accommodation, Ocular↗

PubMed1993

Evidence for 5-HT2 receptor involvement in the stimulation of preovulatory LH and prolactin release and ovulation in normal cycling rats.

The participation of serotonin (5-HT) in the control of LH secretion and ovulation has been reported in numerous pharmacological experiments, although the results have been contradictory. In this study to determine the physiological involvement of 5-HT2 receptors in the control of preovulatory LH and prolactin (PRL) release and ovulation, ketanserin (KET), a selective 5-HT2 receptor antagonist, was administered to normal cycling rats. Oral administration of KET at 10 mg/kg BW between 0900h and 1300h on the day of proestrus completely blocked ovulation, while the administration after 1500h did not. The ovulation was confirmed 2 days after treatment with KET. There was no consistent effect on the number of ova ovulated. Co-administration of KET with 5-methoxy-N,N-dimethyltryptamine (5-MeDMT), a 5-HT agonist, at a dose of 2 mg/kg BW ip reversed KET-induced inhibition of ovulation. The highest rate (89%) of reversal was obtained by co-administration at 1500h. KET administered at 1100h completely blocked the preovulatory surge of LH and PRL observed in control animals at 1800h. The present study suggests that 5-HT stimulates preovulatory LH and PRL surge and ovulation via 5-HT2 receptor under physiological conditions and that the effect of 5-HT depends on the critical period and the 24-hour periodicity.

Animals↗

PubMed1993

Serotonin stimulates steroidogenesis in rat preovulatory follicles: involvement of 5-HT2 receptor.

The role of serotonin (5-HT) in the regulation of steroidogenesis in the ovary via 5-HT2 receptor was studied in normal cycling rats and their preovulatory follicles. Oral administration of ketanserin (KET), a selective 5-HT2 antagonist, at 10 mg/kg BW at 1100h on the day of proestrus resulted in a marked decrease in serum estradiol levels immediately after the administration. 5-HT stimulated estradiol secretion by preovulatory follicles incubated for 5 hrs in Krebs-Ringer bicarbonate buffer. 5-HT (2.5 microM) -enhanced estradiol secretion was inhibited by KET (1-100 microM) in a dose-dependent manner. Secretion of progesterone and testosterone was also inhibited by about the same order of magnitude as estradiol. Addition of pregnenolone (1 microgram/ml) prevented the KET-inhibited progesterone production. Both testosterone and estradiol increased at the same ratio by the addition of progesterone (1 microgram/ml). The inhibition of secretion of these hormones was overcome by dbcAMP (0.1 mM). The present study suggests that 5-HT stimulates steroidogenesis in the metabolic pathway prior to pregnenolone in rat preovulatory follicles and the action of 5-HT could possibly be mediated by a 5-HT2 receptor.

Animals↗

PubMed1993

[Aging changes in accommodation--comparison of subjective method with objective method].

We investigated age-related changes in accommodation of the human eye by measuring the subjective amplitude of accommodation with a Visual Display Terminals Accommodometer (Tokyo-Medical NP-200) and the objective amplitude with an Auto Refkeratometer (Canon, RK-1). The accommodative responses of 5 normal eyes of 5 subjects ranging from 29 to 32 years of age were measured with 6 different sizes of targets. A distinct tendency for the subjective amplitude of accommodation to increase was observed with the targets of larger sizes, but no definite tendency was found in the objective amplitude. The accommodative responses of 92 normal eyes of 92 subjects ranging from 15 to 58 years of age were measured. Both the subjective and objective amplitude of accommodation decreased with aging. In subjects under 44 years of age, the objective amplitude was 2.2-2.5D less than the subjective amplitude, but over 45 the difference between the subjective and objective amplitude was 1.2-1.4D.

Accommodation, Ocular↗

PubMed1991

[Occurrence of Escherichia coli in urinary tract infection].

Regarding P-fimbriae, K1 antigen, sero O-type and factors on the host (age, sex and morbidity) with are the pathogenic factors in E. coli, an assessment has been made as to what relations these factors have in urinary tract infection. By age, cases of P-fimbriae is seen in large numbers among pregnant women and infants but less among the people aged 16-30. A similar trend was observed regarding K1 antigen. An assessment made by sex show a trend that E. coli which carries P-fimbriae tends to emerge frequently in males. By morbidity, P-fimbriated strain was seen in many severe cases among pregnant women and infants. The fact has become evident further as a result of making an investigation with K1 antigen added. However, the result of an assessment made in adult cases showed that P-fimbriae was seen frequently in simple cystitis conversely. As the reason for P-fimbriae being observed more in males, participations of immunological stage and anatomical factors on the host side in the pathogenicity was resumed, and the main cause that P-fimbriae is seen more in severe pregnant and infantile cases was presumed to be vesicoureteral reflux. Regarding group sero O-type and morbidity, the types reported so far were detected also at our hospital, but a very interesting finding we have obtained was that the stains P-fimbriae and K1 antigen were observed in types 2, 12, 18 and 75.

ABO Blood-Group System↗

PubMed1990

An analysis of subretinal fluid in bullous retinal detachment.

A patient with bilateral bullous retinal detachment underwent drainage of the subretinal fluid. The analysis of the subretinal fluid revealed a high protein concentration--17.4 g/dl OD, 27.5 g/dl OS--which was 3-5 times higher than that of the patient's serum. The protein fractionations of the subretinal fluid were almost the same as those of the serum. These findings may well explain the shifting fluid and support the theory that bullous retinal detachment is caused by the breakdown of retinal pigment epithelial function as a barrier between the choroid and retina.

Adult↗

PubMed1985

[Therapeutic effect of TRQ on chronic liver injury model in rats induced by CCl4].

Rats were treated with CCl4 for 12 weeks to induce chronic liver injury. An administration of tritoqualine (TRQ) to rats was begun 3 weeks after the first CCl4 treatment, and the therapeutic effect of TRQ on this model was investigated. On the 12th week after CCl4 treatment, a marked increase in content of hydroxyproline and histamine in the liver was found. In addition, increased fibrosis around Glisson's sheath was observed under microscopic observation. The increase in these biochemical parameters was suppressed significantly in the rats administered TRQ at doses of 25-100 mg/kg. The histopathological observation demonstrated the suppression of the formation of pseudolobules with fibrinogenesis in the liver of TRQ administered rats. In addition, there was a noticeable improvement in the activity of the liver protein synthesis in the TRQ administered rats when the parameters that represented the hepatic functions were measured. Glutamic oxaloacetic transaminase in the serum of TRQ-administered rats also decreased significantly, compared with the CCl4 treated control rats. From these results, TRQ was shown to exhibit a marked therapeutic effect on liver damage accompanied by chronically accelerated fibrosis in rats which have been treated with CCl4 for 12 weeks.

Alanine Transaminase↗