Biomedical subjects

Atsuko Suzuki

Publications and source records attributed to Atsuko Suzuki.

26 records · Page 2Linked to original sources

PubMed2002

Reflex choroidal blood flow responses of the eyeball following somatic sensory stimulation in rats.

The effect of cutaneous mechanical stimulation on choroidal blood flow (ChBF) of the eyeball measured using a laser Doppler flowmeter was examined in anesthetized rats. Noxious pinching stimulation of a forepaw for 20 s produced increases in ChBF and mean arterial blood pressure (MAP), whereas brushing of a forelimb produced no changes in either parameter. After spinal transection at the fourth thoracic (T4) level, forepaw pinching stimulation did not produce any MAP changes in 9 of 11 spinalized rats. In these nine spinalized animals, pinching stimulation of a forepaw produced no significant responses in ChBF. After the cutting of cervical sympathetic trunks in five spinal rats, forepaw pinching showed no effect on MAP, but produced an increase in ChBF, which was abolished by an intravenous (i.v.) injection of 1-(2-trifluoromethylphenyl) imidazole (TRIM), a selective inhibitor of neuronal nitric oxide synthase (nNOS). In another four spinalized rats, whose cervical sympathetic trunks were intact and the superior salivary nucleus (SSN) was destroyed, forepaw pinching showed no effect on MAP, but produced a decrease in ChBF, which was abolished by an i.v. injection of phentolamine, an alpha-adrenoceptor antagonist. The present experiment shows that somatic afferent stimulation can produce reflex responses of the ChBF of the eyeball, either a vasodilative response using parasympathetic efferent fibers or a vasoconstrictive response using sympathetic efferent fibers, independent of systemic blood pressure. It was also shown that the somatically induced vasodilative response was due to a release of nitric oxide (NO) from parasympathetic nerves and the vasoconstrictive response was due to a release of noradrenaline from sympathetic nerves.

Adrenergic alpha-Antagonists↗

PubMed2002

Genome-wide analysis of changes in early gene expression induced by oestrogen.

BACKGROUND: The sex hormone 17beta-oestradiol (E2) has profound effects on many aspects of reproduction, development, as well as behaviour. Although the oestrogen receptor is well characterized on a molecular level, relatively few genes affected by E2 have been identified, and the mechanisms underlying the physiological changes caused by E2 are largely unknown. In order to identify oestrogen-regulated genes in vivo, early uterine gene expression profiles were developed using DNA microarrays. RESULTS: Ovariectomized mice were exposed to 17beta-oestradiol for 6 h, and mRNA expression analysis for 9977 genes was performed. Although a large number of genes was affected by oestrogen administration, the genes that showed higher reproducibility in repetitive experiments were selected and further examined. For most of the selected genes, expression was induced in a dose-dependent manner, and gene expression was not altered following oestrogen treatment in oestrogen receptor-alpha (ER(alpha))-deficient mice. In combination with the estimation of gene expression levels using quantitative PCR, it was revealed that multiple genes related to sterol biosynthesis, tRNA synthesis, RNA processing, and growth signalling were activated. Based on the microarray data, we selected additional genes related to sterol biosynthesis and tRNA synthesis and confirmed that these genes are also activated by oestrogen. CONCLUSION: Genes suggesting a basis for the drastic uterotrophic effect observed several days following oestrogen administration were identified. These findings not only reveal the diverse effect of oestrogen signalling on transcript levels in vivo but also demonstrate the ability of DNA microarrays to identify cellular pathways affected by oestrogen.

Animals↗

PubMed2002

Enantiomer analysis of a new street drug, 3,4-methylenedioxy-N-methyl-butanamine, in rat urine.

A new street drug, 3,4-methylenedioxy-N-methyl-butanamine (MBDB), has been found in Japan recently. The stereoisomer monitoring and the urinary excretion kinetics are not determined in biological fluids even though abused MBDB is a racemic form [enantiomer ratio (-/+) = 1.00]. The present studies were done by high-performance liquid chromatography (HPLC) equipped with a chiral activity column at 40 degrees C using urine specimens from five Wistar rats. Urine samples were collected over six time intervals after a single oral administration of racemic MBDB (30 mg/kg). Unchanged MBDB and 3,4-methylenedioxybutanamine (BDB), an N-demethylated metabolite, were found in the rats' urine. Each enantiomer of MBDB and BDB was monitored (peak resolution > 1.00) by HPLC analysis within 30 min. For both MBDB and BDB, the (+)-isomers were excreted a little more than the (-)-isomers. The stereoselective disposition of BDB was more remarkable than that of MBDB and was observed in the urine throughout the study (p < 0.05). The urinary excretion of MBDB showed significant difference between the two enantiomers from 4 to 20 h (p < 0.05). The amount of MBDB excreted up to 24 h was 34.7+/-2.8% of the administered dose: 17.6+/-1.4% for (+)-isomer and 17.1+/-1.5% for (-)-isomer. The amount of BDB was 4.9+/-1.0%; 2.9+/-0.6% for (+)-isomer and 2.0+/-0.4% for (-)-isomer. The enantiomer ratio (-/+) of MBDB and BDB was 1.00 or a little smaller. The ratio (-/+) of MBDB changed from 1.00+/-0.02 to 0.88+/-0.09 by 24 h, and that of BDB from 0.68+/-0.03 to 0.78+/-0.02. The ratio (-/+) for MBDB and BDB accumulated up to 24 h was 0.97+/-0.01 and 0.70+/-0.06, respectively, and the total ratio (-/+) of the two substances was 0.93+/-0.02 (p < 0.05). These findings suggested that the stereoselective disposition of racemic MBDB was different from that of 3,4-dimethylenedioxyamphetamine and 3,4-dimethylenedioxymethamphetamine and was similar to that of methamphetamine.

3,4-Methylenedioxyamphetamine↗

PubMed2002

Developmental toxicity of estrogenic chemicals on rodents and other species.

Antenatal sex-hormone exposure induces lesions in mouse reproductive organs, which are similar to those in humans exposed in utero to a synthetic estrogen, diethylstilbestrol. The developing organisms including rodents, fish and amphibians are particularly sensitive to exposure to estrogenic chemicals during a critical window. Exposure to estrogens during the critical period induces long-term changes in reproductive as well as non-reproductive organs, including persistent molecular alterations. The antenatal mouse model can be utilized as an indicator of possible long-term consequences of exposure to exogenous estrogenic compounds including possible environmental endocrine disruptors. Many chemicals released into the environment potentially disrupt the endocrine system in wildlife and humans, some of which exhibit estrogenic activity by binding to the estrogen receptors. Estrogen responsive genes, therefore, need to be identified to understand the molecular basis of estrogenic actions. In order to understand molecular mechanisms of estrogenic chemicals on developing organisms, we are identifying estrogen responsive genes using cDNA microarray, quantitative RT-PCR, and differential display methods, and genes related to the estrogen-independent vaginal changes in mice induced by estrogens during the critical window. In this review, discussion of our own findings related to endocrine distuptor issue will be provided.

Animals↗

PubMed2002

[Occurrence of Legionella bacteria in a variety of environmental waters--from April, 1996 to November, 2000].

The present paper deals with the occurrence of Legionella bacteria in a variety of man-made environmental waters, including whirlpool bathes, cooling towers and others, from April 1996 to November 2000 in the eastern part of Japan around Tokyo area. A total of 2,895 water samples were examined for the possible occurrence of Legionella, and 904 (31%) were demonstrated to be positive. Among the various water sources, Legionella were frequently detected both in whirlpool bathes and in cooling towers, of which detection rates were 48% and 46%, respectively. More precisely, occurrence of Legionella was higher in private-use whirlpool bathes than those for public-use; namely, the positive rate was 71% in bathes accommodated in private houses, 63% in company's club houses, 62% in company dormitories for employees, and 51% in old-people's homes. Occurrence of Legionella, on the other hand, was less common (< or = 30%) in bathes for public-use such as those installed in hotels and in hot spring facilities. Typing of L. pneumophila serogroups revealed that SG5 (34%) was dominant in whirlpool bath waters followed by SG3 (22%), whereas SG1 (32%) was dominantly found in cooling tower waters.

Hydrotherapy↗

PubMedDate not supplied

High resolution ultrasonography in eyes with angle-closure glaucoma associated with the cicatricial stage of retinopathy of prematurity.

BACKGROUND: Angle-closure glaucoma in children at the cicatricial stage of retinopathy of prematurity (ROP) has been thought to be caused by the anterior displacement of the lens-iris diaphragm resulting from contraction of a retrolental fibrous membrane. Other possible mechanisms include pupillary block and ciliary block. CASES: Three patients (three eyes) at the cicatricial stage of ROP with angle-closure glaucoma were examined by high-resolution ultrasonography before and after peripheral iridectomy. OBSERVATIONS: High-resolution ultrasonography preoperatively showed that the angle was closed. A retrolental fibrous membrane was attached behind the lens. After the iridectomy, ultrasonography showed an open angle, and the intraocular pressure was normal. CONCLUSIONS: The angle closure in our three patients was caused mainly by a pupillary block and could be treated by peripheral iridectomy.

Anterior Eye Segment↗

PubMedDate not supplied

Developmental effects of perinatal exposure to bisphenol-A and diethylstilbestrol on reproductive organs in female mice.

Reproductive tract development is influenced by estrogen. The aim of this study was to determine the effects of an environmental estrogenic chemical bisphenol-A (BPA) on prenatal and postnatal development of female mouse reproductive organs. In the prenatal treatment group, BPA or the synthetic estrogen diethylstilbestrol (DES) were given by subcutaneous (s.c.) injections to pregnant mice during gestational days 10-18. Some offspring treated prenatally with 10 and 100 mg/kg bw BPA or 0.67 and 67 microg/kg bw DES were ovariectomized at 30 days and sacrificed at 40 days of age. Vaginal smears were examined in the remaining offspring, then these offspring were mated with normal males. Prenatal exposure to 10 mg/kg BPA reduced the number of mice with corpora lutea compared to sesame oil controls at 30 days, but more than 80% of mice from either prenatally exposed BPA group were fertile at 90 days. Mice exposed prenatally to maternal doses of 67 microg/kg DES were sterile and showed ovary-independent vaginal and uterine epithelial stratification; however, mice exposed prenatally to BPA did not show ovary-independent vaginal and uterine changes. The number of offspring and litter sex ratio from mice exposed prenatally to BPA (10 or 100 mg/kg) or 0.67 microg/kg DES were not different compared to controls. In postnatal treatment group, female mice were given s.c. injections of BPA (15 or 150 microg/pup) or DES (0.3 or 3 microg/pup) for 5 days from the day of birth, then some mice were ovariectomized at 30 days and examined at 40 and 90 days. In the remaining mice, vaginal smears were examined from 61 to 90 days and ovarian histology was evaluated at 90 days. Mice exposed postnatally to 150 microg BPA exhibited ovary-independent vaginal epithelial stratification. Postnatal DES (0.3 and 3 microg) treatment also induced ovary-independent vaginal stratification. Polyovular follicles having more than one oocyte in a follicle were induced by postnatal injections of BPA (150 microg) or DES (0.3 or 3 microg) at 30 days. These findings indicate for the first time that a large dose of BPA can induce ovary-independent vaginal epithelial changes when given postnatally but not prenatally.

Animals↗

PubMedDate not supplied

Low dose effect of in utero exposure to bisphenol A and diethylstilbestrol on female mouse reproduction.

In utero exposure to bisphenol-A (BPA) at doses relevant to human consumption has been reported to accelerate weight gain and puberty in female mice, but the effect of low dose BPA on female reproduction has not been described. In this study, we investigated low dose effects of BPA on sexual maturation and reproduction in female ICR/Jcl mice. Pregnant ICR mice (F0) were injected (s.c.) with BPA (2 and 20 microg/kg), diethylstilbestrol (DES; 0.02, 0.2, and 2 microg/kg) or oil vehicle once per day from gestational days 11-17. For both female and male offspring (F1), body weights were measured on postnatal day (PND) 0 (the day of birth), 11, 22, and 60, and anogenital distance (AGD) was measured on PNDs 22 and 60. Pups were weaned at PND 22 and males were caged separately from females. Vaginal smears were taken daily beginning the day of vaginal opening for 30 days. The age at vaginal opening was significantly earlier in all exposed females except for 2 microg/kg BPA females compared to oil controls. Body weight at vaginal opening was lower than controls in all exposed females. The first vaginal estrus was earlier in all exposed females except for the 2 microg/kg BPA group females compared to controls. From PND 90 to 120, gestationally exposed F1 female mice were mated with unexposed males. Total numbers of pups and sex ratio in F1 mice exposed to BPA or DES, and those of their offspring (F2) were not different from controls in any treatment group. The present results indicate that prenatal exposure to low doses of BPA and DES induces early vaginal opening, but does not affect reproductive functioning at the first breeding.

Animals↗