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Biomedical subjects

Taro Takahashi

Publications and source records attributed to Taro Takahashi.

10 recordsLinked to original sources
PubMed2006

Prenatal stress suppresses cell proliferation in the early developing brain.

Although prenatal stress has been repeatedly shown to inhibit adult neurogenesis in the dentate gyrus of offspring, its effects on embryonic and early postnatal brain development are not well described. Here, using the cell proliferation marker 5-bromo-2'-deoxyuridine, we examine for the first time the effect of prenatal stress at the embryonic stage on cell proliferation in the hippocampus, nucleus accumbens and amygdala. We show that prenatal stress induces a significant decrease in density of 5-bromo-2'-deoxyuridine-positive cells in the nucleus accumbens (40%) and hippocampus (60%), and a nonsignificant decrease in the amygdala (30%). Taken together, these results demonstrate the adverse effects of prenatal maternal stress on early development in limbic brain regions and the potential mechanisms are discussed.

Animals↗
PubMed2004

Southern Ocean iron enrichment experiment: carbon cycling in high- and low-Si waters.

The availability of iron is known to exert a controlling influence on biological productivity in surface waters over large areas of the ocean and may have been an important factor in the variation of the concentration of atmospheric carbon dioxide over glacial cycles. The effect of iron in the Southern Ocean is particularly important because of its large area and abundant nitrate, yet iron-enhanced growth of phytoplankton may be differentially expressed between waters with high silicic acid in the south and low silicic acid in the north, where diatom growth may be limited by both silicic acid and iron. Two mesoscale experiments, designed to investigate the effects of iron enrichment in regions with high and low concentrations of silicic acid, were performed in the Southern Ocean. These experiments demonstrate iron's pivotal role in controlling carbon uptake and regulating atmospheric partial pressure of carbon dioxide.

Atmosphere↗
PubMed2003

Decadal variation of the surface water PCO2 in the western and central equatorial Pacific.

The equatorial Pacific Ocean is one of the most important yet highly variable oceanic source areas for atmospheric carbon dioxide (CO2). Here, we used the partial pressure of CO2 (PCO2), measured in surface waters from 1979 through early 2001, to examine the effect on the equatorial Pacific CO2 chemistry of the Pacific Decadal Oscillation phase shift, which occurred around 1988 to 1992. During the decade before the shift, the surface water PCO2 (corrected for temperature changes and atmospheric CO2 uptake) in the central and western equatorial Pacific decreased at a mean rate of about -20 microatm per decade, whereas after the shift, it increased at about +15 microatm per decade. These changes altered the CO2 sink and source flux of the equatorial Pacific significantly.

Journal Article↗
PubMed2003

Ingestion of water-soluble soybean fiber prevents osteopenia and hypercholesterolemia induced by ovariectomy in rats.

This study examined the effects of feeding water-soluble soybean fiber (WSSF), a highly fermentable dietary fiber with low viscosity, on intestinal calcium (Ca) absorption, bone mineral content, and serum total cholesterol levels using female Sprague-Dawley rats (5 weeks old) with or without ovariectomy (OVX). The rats in each group were fed a WSSF (50 g/kg of diet) or WSSF-free diet for 4 weeks. Ca absorption was higher in OVX rats fed the WSSF diet than in OVX rats fed the WSSF-free diet. Femoral Ca content in both sham and OVX rats fed the WSSF diet was higher than that in rats fed the WSSF-free diet. The serum total cholesterol levels were elevated after OVX compared with that in the sham rats, and this elevation was prevented by the WSSF diet. In conclusion, ingestion of WSSF prevented osteopenia and hypercholesterolemia induced by ovariectomy in rats.

Animals↗
PubMed2003

Comparison of hangover effects among triazolam, flunitrazepam and quazepam in healthy subjects: a preliminary report.

The aim of the present study was to compare the hangover effects of night-time administration of triazolam (0.25 mg), flunitrazepam (1 mg) and quazepam (15 mg) in healthy subjects. Daytime sleepiness and performance level following the night-time administration of the drugs were assessed using Standford Sleepiness Scale (SSS), Sleep Evaluation Questionnaire (SEQ), Multiple Sleep Latency Test (MSLT), actigraphy recordings and Continuous Performance Test (CPT). Fifteen healthy volunteers were given one of the three hypnotics at each drug session, which lasted for 1 week, in a single-blind cross-over fashion. No significant between-drug difference was observed for the psychomotor performance assessed by CPT. Subjective hangover effects assessed by SSS and SEQ in the morning were prominent for flunitrazepam and quazepam relative to triazolam, whereas objective indices such as MSLT or activity counts obtained in actigraphy indicated a marked hangover effect of quazepam compared with the other two compounds restrictively in the afternoon, which were nearly in accordance with their pharmacokinetic profiles.

Activities of Daily Living↗
PubMed2002

Towards robust regional estimates of CO2 sources and sinks using atmospheric transport models.

Information about regional carbon sources and sinks can be derived from variations in observed atmospheric CO2 concentrations via inverse modelling with atmospheric tracer transport models. A consensus has not yet been reached regarding the size and distribution of regional carbon fluxes obtained using this approach, partly owing to the use of several different atmospheric transport models. Here we report estimates of surface-atmosphere CO2 fluxes from an intercomparison of atmospheric CO2 inversion models (the TransCom 3 project), which includes 16 transport models and model variants. We find an uptake of CO2 in the southern extratropical ocean less than that estimated from ocean measurements, a result that is not sensitive to transport models or methodological approaches. We also find a northern land carbon sink that is distributed relatively evenly among the continents of the Northern Hemisphere, but these results show some sensitivity to transport differences among models, especially in how they respond to seasonal terrestrial exchange of CO2. Overall, carbon fluxes integrated over latitudinal zones are strongly constrained by observations in the middle to high latitudes. Further significant constraints to our understanding of regional carbon fluxes will therefore require improvements in transport models and expansion of the CO2 observation network within the tropics.

Journal Article↗
PubMedDate not supplied

Ingestion of water-soluble soybean fiber improves gastrectomy-induced calcium malabsorption and osteopenia in rats.

OBJECTIVE: Total gastrectomy produces calcium malabsorption and osteopenia. We examined the effects of feeding water-soluble soybean fiber (WSSF), a highly fermentable dietary fiber with low viscosity, on calcium absorption and bone characteristics in totally gastrectomized rats. METHODS: Male Sprague-Dawley rats were assigned to two groups: sham operation and gastrectomy. After the postoperative recovery period, rats of each group were fed diets with or without WSSF (50 g/kg diet) for 4 wk. RESULTS: Net calcium absorption and femoral dry weight and calcium content and maximum breaking force were lower in the gastrectomy groups than in the sham groups. In the gastrectomy groups, calcium absorption and these femoral parameters were higher in rats fed the WSSF diet than in rats fed the WSSF-free diet. Feeding WSSF increased the concentrations of short-chain fatty acids and soluble calcium and decreased the pH in cecal contents. Net calcium absorption in gastrectomized rats correlated positively with the concentration of total short-chain fatty acids (the sum of acetic, propionic, and butyric acids) in cecal contents (r = 0.545, P < 0.05) and negatively with cecal pH (r = -0.628, P < 0.05). CONCLUSIONS: These findings indicate that ingestion of WSSF partly prevents the diminished calcium absorption after total gastrectomy in rats, resulting in the improvement of postgastrectomy osteopenia. The increase of calcium absorption may be associated with cecal fermentation of WSSF.

Acetic Acid↗
PubMedDate not supplied

Condensation reaction between angiotensin II and dicarboxylic acid in water at high temperature without any catalytic agent additive.

The condensation reaction of angiotensin II and tartaric acid in water at 100-140 degrees C proceeded without any added catalytic agent. One of the products, N-CO-tartarylangiotensin II, was confirmed by LC-MS, positive-ion MALDI-MS, and the fluorescamine method as a condensation product. The initial concentration of the substrates, temperatures, and initial pH affected the yield of the product. The higher concentrations and temperatures increased the concentration of the condensation product. The optimal pH for the condensation reaction was 3.0. The other C4 saturated dicarboxylic acids, malic and succinic acids, were also condensed by angiotensin II.

Angiotensin II↗