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Biomedical subjects

Y Takeda

Publications and source records attributed to Y Takeda.

At least 595 records · Page 33Linked to original sources
PubMed1994

Decreased activity of 11 beta-hydroxysteroid dehydrogenase in mesenteric arteries of Dahl salt-sensitive rats.

11 beta-Hydroxysteroid dehydrogenase (11 beta-HSD) activity in mesenteric arteries of 4-week- and 8-week-old Dahl rats was determined to evaluate the relationship between glucocorticoids and norepinephrine in hypertension, 11 beta-HSD activity (expressed as the percentage conversion of 3H-corticosterone (B) to 3H-11-dehydrocorticosterone (A)) significantly decreased in 8-week-old Dahl salt-sensitive (DS) rats (11.4 +/- 1.4%) compared with Dahl salt-resistant (DR) rats (15.3 +/- 0.3%) (p < 0.05) when each group was fed a high-sodium chow (7%) for 4 weeks. There were no significant differences in 11 beta-HSD activity in the 4-week-old DS and DR rats. The enhanced response of mesenteric arteries to norepinephrine was observed only in 8-week-old DS rats. Our results suggest that a decreased 11 beta-HSD activity in the vascular walls contributes to the increased response of norepinephrine by local increment of glucocorticoids in DS hypertensive rats.

11-beta-Hydroxysteroid Dehydrogenases↗
PubMed1994

Expression of 11 beta-hydroxysteroid dehydrogenase mRNA in rat vascular smooth muscle cells.

The enzyme 11 beta-hydroxysteroid dehydrogenase (11-HSD) converts corticosterone to the inactive 11-dehydrocorticosterone in the rat. The bioactivity of 11-HSD, expressed as the percentage conversion of 3H-corticosterone to 3H-11-dehydrocorticosterone, was 13.7 +/- 0.4% in rat vascular smooth muscle cells (rVSMC). Cells treated with 100 nM dexamethasone (Dex) showed a 1.4-fold (p < 0.05) increase in 11-HSD activity. Insulin (100 microM) decreased 11-HSD activity by 0.8-fold (p < 0.05). Expression of 11-HSD mRNA was also confirmed in rVSMC by Northern blot analysis. Dexamethasone increased and insulin decreased the levels of 11-HSD mRNA in parallel with the increase in bioactivity. Vascular smooth muscle cells express 11-HSD activity; the access of corticosterone to vascular smooth muscle receptors may be modulated by the enzyme.

11-beta-Hydroxysteroid Dehydrogenases↗
PubMed1994

The activities of 5 beta-reductase and 11 beta-hydroxysteroid dehydrogenase in essential hypertension.

The activities of 11 beta-hydroxysteroid dehydrogenase (11 beta-HSD) and 5 beta-reductase were analyzed in 39 normotensive controls and 128 patients with essential hypertension. The activity of 11 beta-HSD was obtained by dividing the 24-hour urinary tetrahydrocortisone by the sum of tetrahydrocortisol (THF) and allotetrahydrocortisol (aTHF), whereas the activity of 5 beta-reductase was obtained by dividing the 24-hour urinary THF by aTHF. The activity of 5 beta-reductase was significantly lower in essential hypertensives compared with normotensive controls (P < 0.05). However, the activity of 11 beta-HSD did not differ between normotensive controls and essential hypertensives. A positive correlation between the activities of 11 beta-HSD and 5 beta-reductase was observed in essential hypertensives (r = 0.60, P < 0.01). Neither 11 beta-HSD nor 5 beta-reductase activity correlated with indices of renal mineralocorticoid receptor activation, which were assessed by determination of plasma potassium and urinary excretion of sodium as well as potassium. Taken together, these results suggest that disturbances of one of the inactivation pathways of cortisol may contribute to the pathogenesis of hypertension.

11-beta-Hydroxysteroid Dehydrogenases↗
PubMed1994

Analysis of glycosaminoglycans by high-performance liquid chromatography.

Glycosaminoglycan chains were liberated from proteoglycan by successive digestion with protease and endo-beta-xylosidase. The glycosaminoglycan chains were then labeled with a fluorescent reagent, 2-aminopyridine, by reductive amination. The resulting pyridylamino-glycosaminoglycans, including hyaluronic acid, heparan sulfate, chondroitin sulfate/dermatan sulfate and heparin, were separated by ion-exchange high-performance liquid chromatography using a TSK gel SAX analytical column with a limit of sensitivity in the picomol range. With the combined use of a dermatan sulfate-degrading enzyme, chondroitinase B, chondroitin sulfate and dermatan sulfate were identified and quantified, separately. About 50 mg of wet animal tissue was enough for analysis of each glycosaminoglycan with satisfactory results. This method facilitates rapid separation and microanalysis of glycosaminoglycans.

Animals↗
PubMed1994

Effect of antitumor polysaccharide SPR-901 on antitumor activity in combination with 5-FU.

We have examined the effects of the antitumor polysaccharide SPR-901 in combination with 5-fluorouracil (5-FU) on the antitumor activities against mouse syngeneic tumors. SPR-901 was administered p.o. from day 1 to day 10 at the dose rate of 30 mg/kg, and 5-FU was injected i.p. from day 1 to day 5 at the dose rate of 20 mg/kg after BALB/c mice were injected s.c. with 6 x 10(4) cells/mouse of Meth A on day 0. Tumor sizes of mice treated with both SPR-901 and 5-FU were significantly smaller than those from the untreated control group on days 10, 15 and 20. LAK activity of spleen cells from mice treated with both SPR-901 and 5-FU was higher than that from the untreated control group and either the SPR-901 or 5-FU treated group. Flow cytometrical analysis revealed that spleen cells from mice treated with both SPR-901 and 5-FU were much more abundant in both T-cell receptor alpha/beta+ and IL-2 receptor alpha+ T-cells. Furthermore, spleen cells from both the SPR-901- and 5-FU-treated groups exhibited higher growth responses to IL-2 than that from the untreated control group and either of the SPR-901- or 5-FU-treated groups. Therefore, the effects of the antitumor polysaccharide SPR-901 used in combination with 5-FU were augmented as compared with single drug use.

Animals↗
PubMed1994

Enhancement of the positive inotropic effect mediated by alpha 1-adrenoceptors in pertussis toxin-treated rabbit papillary muscles.

1. In rabbit papillary muscles, pretreatment with pertussis toxin (PTX) significantly increased the positive inotropic response to isoprenaline and abolished the inhibitory action of carbachol on the isoprenaline response. 2. Phenylephrine in the presence of propranolol produced a positive inotropic effect and prolonged action potential duration through activation of alpha 1-adrenoceptors. Both of the effects of phenylephrine were significantly enhanced by PTX pretreatment. 3. Accumulation of [3H]inositol monophosphate (IP1) in papillary muscles prelabeled with myo-[3H]inositol was increased by phenylephrine in a concentration-dependent manner, which was antagonized by prazosin. Although PTX pretreatment significantly elevated the basal level of [3H]IP1 formation, the phenylephrine-induced increase in [3H]IP1 formation was unaffected. 4. It is concluded that the cardiac responses to alpha 1-adrenoceptor stimulation studied in these experiments are not transduced by a PTX sensitive G protein (Gi). However, the positive inotropic effect and prolongation of action potential duration mediated by alpha 1-adrenoceptor may be negatively regulated by Gi.

Action Potentials↗
PubMed1994

Effect of aging on urinary excretion of 18-hydroxycortisol.

The secretion of aldosterone declines with age. We reported that sodium depletion increased urinary excretion of 18-hydroxycortisol (18-OH-F). To elucidate the effect of aging on urinary excretion of 18-OH-F, we measured urinary 18-OH-F in 30 normotensive subjects aged 20-70 yr. There were significant negative correlations between age and urinary excretion of 18-OH-F or of aldosterone (r = -0.49, r = -0.58, P < 0.05, respectively) but not of urinary free cortisol. These results suggest that angiotensin may contribute to chronic regulation of 18-OH-F.

Adult↗
PubMed1994

Biosynthetic pathway of 19-noraldosterone in isolated rat glomerulosa cells.

The biosynthetic pathway of 19-noraldosterone (19-noraldo) in isolated rat glomerulosa cells (GC) and fasciculata-reticular cells (FC) was studied by analyzing [14C]pregnenolone metabolism using HPLC and quantification by specific RIA. In GCs, 18,19-dihydroxycorticosterone was detected after 15 min incubation with [14C]pregnenolone, 18-hydroxy-19-norcorticosterone was detected after 30 min and 19-noraldo was detected after 45 min before the appearance of an aldosterone peak. These three mineralocorticoids were not detected in FCs. The results demonstrate that 19-noraldo is synthesized in GCs and then undergoes further metabolism.

18-Hydroxycorticosterone↗
PubMed1994

Biomechanical function of the human anterior cruciate ligament.

Knowledge about the biomechanical function of the anterior cruciate ligament (ACL) is very important in the treatment of the ACL deficient knee. This article presents an overview of the biomechanical function of the ACL, including its structural and mechanical properties as well as its role in knee stabilization and normal kinematics. Tensile properties of the prospective biological grafts and future directions in ACL research are also discussed.

Anterior Cruciate Ligament↗
PubMed1994

Physiological characteristics of inferior vena cava pulse waveform during foetal development.

Non-invasive measurements of pulsatile diameter changes (pulse waveform) in the foetal inferior vena cava (IVC) during foetal development using an ultrasonic phase-locked echo tracking system with high sampling frequency (3000 Hz) are described. Successful human foetal IVC pulse waveform recording was achieved cross-sectionally in 56 out of 68 (82%) women at 20-23, 24-27, 28-31, 32-35, and 36-39 weeks' gestation. The pulse waveform in the foetal IVC consisted of four waves (A, X, V, and Y waves). An increase in the depth of the X and Y descents was observed during the second trimester. It was considered that this was due to the decrease in placental resistance. A slightly decreased foetal heart rate during the third trimester affected the time for right ventricular diastolic filling. Our findings indicate that the alterations in resistance to right ventricular afterload produced by growth in the placenta and right atrioventricular filling patterns with advancing gestational age are reflected in the foetal IVC pulse waveform. In addition, foetal systemic and placental vascular resistance profoundly influence right atrioventricular filling patterns. It is possible to record the foetal IVC pulse waveform simply, using a quite different ultrasound methodology (phase-locked echo tracking) from that used for normal pulse echo or Doppler measurements. Such studies provide important physiological information about the normal foetus.

Adult↗
PubMed1994

Spread of Vibrio cholerae O139 Bengal in India.

Vibrio cholerae serogroup O139 Bengal, a novel strain with epidemic potential, completely displaced V. cholerae serogroup 01 in Calcutta in January 1993, which was followed by an epidemic caused by V. cholerae O139 in March-May 1993. From November 1992 to July 1993, 95.6% of 916 V. cholerae isolates submitted to the National Institute of Cholera and Enteric Diseases from 28 locations in India were confirmed as serogroup O139. As of July 1993, V. cholerae O139 had been isolated from 13 Indian states and a union territory, and large outbreaks of cholera caused by the O139 serogroup had occurred in several cities. The extent of spread of V. cholerae O139 Bengal in India and its ability to swiftly disseminate leaves little doubt that this is the beginning of the eighth pandemic of cholera.

Adolescent↗
PubMed1994

Neural cell adhesion proteins and neurological diseases.

Neural cell adhesion proteins play important roles in neural development and are involved in various neurological diseases. P0, a major protein in mammalian peripheral myelin, mediates not only homophilic cell adhesion but also neurite outgrowth. The P0 glycopeptide inhibits the cell adhesion, but not the neurite outgrowth. Several point mutations of the P0 gene in human chromosome 1q22-23 were found in Charcot-Marie-Tooth (CMT) disease type 1B and Dejerine-Sottas (DS) disease. PASII/PMP22 and connexin 32 were also reported as target proteins of similar hereditary neuropathies. L1 is a large multifunctional protein involved in cell adhesion, neurite outgrowth, fasciculation, and neuronal cell migration. A short isoform of L1 localizes in non-neuronal cells in contrast to the complete L1 exclusively expressed in neurons. Recently various L1 mutations have been reported in X-linked hydrocephalus, MASA syndrome with mental retardation and spastic paraplegia type 1. Further studies on the mutations and disease phenotypes are important and interesting.

Animals↗
PubMed1994

Vibrio mimicus with multiple toxin types isolated from human and environmental sources.

A collection of 13 strains of Vibrio mimicus, including both clinical and environmental isolates from different geographic regions, was examined for various toxins. One strain of environmental origin produced cholera-like toxin (CT) which was completely absorbed with anti-CT immunoglobulin G, five strains produced a haemolysin that cross-reacted with the thermostable direct haemolysin of V. parahaemolyticus and DNA from two strains hybridised with a DNA probe specific for the heat-stable enterotoxin of V. cholerae non-O1. Culture supernates of all strains produced a factor that was cytotoxic to Vero and Chinese hamster ovary cells. In this study, we were able to identify strains of V. mimicus that produced, or had the genetic potential to produce, several toxin types simultaneously. The role of these strains as genetic reservoirs is discussed.

Animals↗
PubMed1994

Specific detection of a verotoxin 2 variant, VT2vp1, by a bead-enzyme-linked immunosorbent assay.

A bead-enzyme-linked immunosorbent assay to specifically detect a Verotoxin 2 variant, VT2vp1, was developed. The sensitivity of the bead-ELISA was 200 pg/ml of the purified VT2vp1 and it did not react with 20 ng/ml of the purified VT2. The specificity of the bead-ELISA was examined with 107 strains of Verocytotoxin-producing Escherichia coli that include VT1-, VT2-, VT2vha-, VT2vhb- and VT2vp1-producing E. coli, and only VT2vp1-producing E. coli that were confirmed by VT2vp1-specific polymerase chain reaction gave positive results. It was noted that all 58 VT2vp1-producing E. coli strains were from pigs, but not from cows and humans.

Animals↗
PubMed1994

Construction of mutant genes for a non-toxic verotoxin 2 variant (VT2vp1) of Escherichia coli and characterization of purified mutant toxins.

The gene encoding a Verotoxin 2 variant, VTvp1, was mutated by oligonucleotide-directed site-specific mutagenesis. Among 6 mutant toxins encoded by the mutated genes, E167Q-R170L (glutamic acid at position 167 and arginine at position 170 from N-terminus of the A subunit were replaced by glutamine and leucine, respectively) was found to have markedly decreased activities; inhibition of protein synthesis, Vero cell cytotoxicity and mouse lethality of the purified E167Q-R170L were 1/1,900, 1/125,000 and 1/2,000, respectively, of those of the purified wild-type VT2vp1. Since the antigenic property of the E167Q-R170L was demonstrated to be similar to that of the wild-type VT2vp1 by Ouchterlony double gel diffusion test and by neutralization test of Vero cell cytotoxicity of the VT2vp1, a possibility to use the mutant VT2vp1, E167Q-R170L, as a toxoid is discussed.

Animals↗