Search PubMed⌕ Search

Biomedical subjects

S Yamada

Publications and source records attributed to S Yamada.

At least 667 records · Page 37Linked to original sources
PubMed1996

Effect of fasting and immobilization stress on estrogen receptor immunoreactivity in the brain in ovariectomized female rats.

The present study examined the effect of 48-h fasting and 1-h immobilization on estrogen receptor immunoreactivity in selected hypothalamic areas and the nucleus of the solitary tract (NTS) in ovariectomized rats. Fasting induced an increase in ER-immunoreactive cells in the paraventricular nucleus (PVN), periventricular nucleus (PeVN) and NTS compared with the unfasted control group. Similarly, immobilization caused an increase in ER-positive cells in the same areas, PVN, PeVN and NTS, versus the non-immobilized group. There was no significant increase in the number of ER-immunoreactive cells in the preoptic area (POA), arcuate nucleus (ARC) or ventromedial hypothalamic nucleus (VMH) following fasting and immobilization. Our previous work in ovariectomized rats with estrogen microimplants in the brain revealed that the PVN and A2 region of the NTS are the feedback sites of estrogen in activating the neural pathway to suppress pulsatile LH secretion during 48-h fasting. The result in the food-deprived rats suggests that estrogen modulation of the suppression of LH secretion during fasting is partly due to the increase in estrogen receptors in the PVN and A2 region. The physiological significance of the increase in neural ER following immobilization remains to be elucidated.

Animals↗
PubMed1996

Neutrophil elastase inhibitor (ONO-5046) decreases cytokine-induced neutrophil chemoattractant after reperfusion of pancreaticoduodenal transplantation in rats.

The protective effects of a neutrophil elastase inhibitor (ONO-5046) on reperfusion injury following pancreaticoduodenal transplantation in rats were studied by measuring serum concentrations of cytokine-induced neutrophil chemoattractant (CINC). Male Wistar rats were transplanted with syngeneic pancreaticoduodenal grafts. ONO-5046 was injected intravenously 5 min before vascular clamping and immediately after reperfusion at a dose of 10 mg/kg. No significant differences were observed in the peak serum concentrations of amylase between the groups treated with and treated without ONO-5046. The serum lipase concentrations in the untreated animals increased and peaked 3 hr after reperfusion. ONO-5046 significantly decreased the peak serum lipase concentration. The serum CINC concentrations, which were determined by enzyme-linked immunosorbent assay, increased and peaked 3 hr after reperfusion, decreasing gradually thereafter. However, pretreatment with ONO-5046 significantly inhibited the rise in serum CINC concentrations after reperfusion. Expression of CICN transcripts in the pancrease grafts was evaluated by Northern blot analysis and peaked 3 hr after reperfusion in untreated animals. Pretreatment with ONO-5046 also significantly inhibited the expression of CINC mRNA transcripts in the graft. ONO-5046 significantly decreased the number of neutrophils accumulated in the pancreas graft 24 hr after transplantation. In vitro CINC production by peritoneal macrophages was increased by neutrophil elastase in dose-dependent fashion. However, ONO-5046 decreased CINC production by peritoneal macrophages in response to neutrophil elastase. These results suggest that ONO-5046 prevents early neutrophil accumulation in the pancreas following ischemia/reperfusion of pancreaticoduodenal transplantation.

Animals↗
PubMed1996

Vagus nerve mediates the increase in estrogen receptors in the hypothalamic paraventricular nucleus and nucleus of the solitary tract during fasting in ovariectomized rats.

The effect of total subdiaphragmatic vagotomy on estrogen-receptor immunoreactivity (ERIR) in the paraventricular nucleus (PVN) and nucleus of the solitary tract (NTS) was examined in fasted ovariectomized rats to clarify the peripheral inputs mediating fasting-induced increase in ERIR in these two nuclei. Vagotomy abolished the effect of 48-h fasting on the expression of ER in these two areas. The result indicates that the neural signal(s) that increase the expression of ER in the PVN and A2 region of the NTS following 48-h fasting is transmitted through the vagus. The involvement of the vagus in the fasting-induced increase in ER in the PVN and A2 region may also be the same neural pathway involved in the suppression of pulsatile luteinizing hormone secretion in fasted female rats.

Animals↗
PubMed1996

Localization and synthesis of acetylcholine in human leukemic T cell lines.

In order to clarify the origin of acetylcholine (ACh) in human blood, we measured the content and synthesis activity of ACh in several human leukemic cell lines. The intracellular ACh content determined by a specific and sensitive radioimmunoassay in the human leukemic T cell lines, HSB-2, MOLT-3, and CEM, was 79.6, 36.2, and 9.5 pmol/10(6) cells, respectively. These values were 9-70-fold higher than those of other cell lines, including a helper T cell line, Jurkat. Stimulation of HSB-2 and MOLT-3 by phytohemagglutinin (PHA) increased both the intracellular content and release of ACh into the culture medium, but did not influence the intracellular content and release of ACh in CEM. ACh synthesis activity was found in all the T cell lines tested. Bromoacetylcholine (100 microM), a choline acetyltransferase (ChAT) inhibitor, and bromoacetyl-L-carnitine (100 microM), a carnitine acetyltransferase (CarAT) inhibitor, decreased ACh-synthesizing activity in MOLT-3, and HSB-2 and CEM, by about 50% and 30%, respectively, indicating that both ChAT, and to a lesser extent CarAt, are involved in ACh synthesis in T cells. These results suggest that T lymphocytes have the potential to synthesize and release ACh, which may play a role in regulating T cell-dependent immune responses.

Acetylcholine↗
PubMed1996

IL-12 produced by antigen-presenting cells induces IL-2-independent proliferation of T helper cell clones.

We investigated the role of IL-12 in proliferation of various Th cell clones (class II-alloreactive (4-86 and 4-55) and keyhole limpet hemocyanin + self I-Ek-reactive (9-16)) following stimulation with Ag on APCs. These clones proliferated in response to stimulation with rIL-2, rIL-12, or Ag/APC. The proliferation induced by Ag/APC stimulation was not affected by anti-IL-2 Ab but was markedly inhibited by anti-IL-12 Abs. Consistent with this finding was the absence of detectable IL-2 activity in culture supernatants 12 to 48 h after Ag/APC stimulation, and the detection of significant levels of IL-12 in an Ab-capture bioassay. IL-12 was produced within 12 h after Ag/APC stimulation, reaching a peak after 18 to 24 h. The production of IL-12 in cultures of Th clones and APC contrasted with the production of IL-2 but not IL-12 upon allostimulation of primary T cells and the inhibition of their proliferation exclusively by anti-IL-2 Abs. Analysis of the expression of IL-12-binding sites on Th cells revealed low levels of IL-12 receptors in resting Th clones but high IL-12R levels 2 to 3 days after Ag/APC stimulation, declining gradually thereafter. The changes in IL-12R expression levels correlated closely with the IL-12 responsiveness of Th populations at various times after Ag/APC stimulation; Th populations obtained 3 and 10 days after Ag/APC stimulation exhibited very high and weak or marginal responsiveness to rIL-12, respectively, whereas the responses to rIL-2 were comparable in both Th populations. These results indicate that the Ag/APC-stimulated proliferation of terminally differentiated Th clones, in contrast to naive T cells, depends on the production of IL-12 by APC and on the simultaneous up-regulation of IL-12R on Th cells rather than on an IL-2 autocrine mechanism.

Animals↗
PubMed1996

Digital sensory nerve conduction velocity and vibration perception threshold in peripheral neurological test for hand-arm vibration syndrome.

To evaluate peripheral neuropathy in patients with vibration syndrome, an examination was conducted of sensory nerve conduction velocity (SCV) in the digital segment of the median nerve in the middle finger and vibration perception threshold (VPT) at 125 Hz on the same middle fingertip. In addition, possible correlations were investigated between the two measurements. SCVs in the digital segment were measured by stimulating at the wrist electrically and recording from two pairs of electrodes in the finger. Fractionated SCVs were also measured in the palm-to-finger, wrist-to-palm, and elbow-to-wrist segments. The subjects were 52 patients with vibration syndrome and 40 healthy controls of similar age. SCVs in the digital segment and the wrist-to-palm segment were significantly slower in the patients than in the controls, and VPTs were higher in the patients. The strongest correlation of VPTs with SCVs among nerve segments measured was shown in the digital segment. With an increase in VPTs, SCVs in the digital segment tended to be slower, and slowed digital SCVs were encountered more frequently: 13% in VPTs below 5.0 dB and 56% in VPTs above 17.5 dB. Slowed digital SCVs were found in 43% of the patients and increased VPTs were encountered in 92%.

Arm↗
PubMed1996

Immunocytochemical localization of the Pit-1 protein in the pituitary of the rainbow trout (Oncorhynchus mykiss).

Pit-1 is a pituitary-specific transcription factor responsible for activating the growth hormone (GH) gene family. The localization of Pit-1 protein in the pituitary of rainbow trout was studied by immunocytochemical analysis. Fish Pit-1 was found to be extensively localized in the nuclei of cells in the proximal pars distalis (PPD), rostral pars distalis (RPD), and pars intermedia (PI). Sagittal sections were immunocytochemically double stained with antibodies against Pit-1, GH, prolactin (PRL), and somatolactin (SL). The results showed that Pit-1 protein was present in the GH-containing cells of the PPD, the PRL-containing cells of the RPD, and the SL-containing cells of the PI.

Animals↗
PubMed1996

Preparation of a series of sulfated tetrasaccharides from shark cartilage chondroitin sulfate D using testicular hyaluronidase and structure determination by 500 MHz 1H NMR spectroscopy.

Six tetrasaccharide fractions were isolated from shark cartilage chondroitin sulfate D by gel filtration chromatography followed by HPLC on an amine-bound silica column after exhaustive digestion with testicular hyaluronidase. Their structures were determined unambiguously by one- and two-dimensional 500 MHz 1H NMR spectroscopy in conjunction with HPLC analysis of chondroitinase AC-II digests of the tetrasaccharides. One fraction was found to contain two tetrasaccharide components. All of the seven tetrasaccharides shared the common core structure GlcA beta 1-3GalNAc beta 1-4GLcA beta 1-3GalNAc with various sulfation profiles. Four were disulfated comprising of two monosulfated disaccharide units GLcA beta 1-3GalNAc(4-sulfate) and/or GlcA beta 1-3GalNAc(6-sulfate), whereas the other three were hitherto unreported trisulfated tetrasaccharides containing a disulfated disaccharide unit GlcA(2-sulfate)beta 1-3GalNAc(6-sulfate) and a monosulfated disaccharide unit GlcA beta 1-3GalNac(4- or 6-sulfate). These sulfated tetrasaccharides were demonstrated to serve as appropriate acceptor substrates for serum alpha-N-acetylgalactosaminyltransferase, indicating their usefulness as authentic oligosaccharide substrates or probes for the glycobiology of sulfated glycosaminoglycans.

Animals↗
PubMed1996

Age-related decrease in responsiveness to L-DOPA is not due to changes in dopamine receptor mRNAs or G protein mRNAs.

To clarify the cause of the age-related decrease in the responsiveness to L-DOPA seen in parkinsonian patients, we studied age-related changes in the mRNA levels of dopamine receptors (D1, D2) and of G proteins (Gs, Gi, Go) in 22 control human brains aged 50-105 years. Neither the mRNA levels of dopamine receptors or of the G proteins changed with age. Another factor in the receptor-G protein cascade, such as guanine nucleotide binding, may cause the age-related decrease in responsiveness.

Actins↗
PubMed1996

Analysis of the STR loci HUMF13A01, HUMFXIIIB, HUMLIPOL, HUMTH01, HUMTPOX and HUMVWFA31 in a Japanese population.

Population studies on six short tandem repeat loci, HUMF13A01, HUMFXIIIB, HUMLIPOL, HUMTH01, HUMTPOX and HUMVWFA31 were carried out in a sample of unrelated Japanese individuals (n = 337-545) living in Gifu Prefecture (central region of Japan). Five alleles could be identified for HUMFXIIIB, six for HUMF13A01, HUMLIPOL, HUMTH01 and HUMTPOX, and eight for HUMVWFA31. For all/six loci no deviations from the Hardy-Weinberg equilibrium hypothesis were detected. The mean exclusion chance ranged from 0.22 to 0.60, the power of discrimination from 0.63 to 0.93, and the expected heterozygosity from 0.43 to 0.80. Allele frequency distributions for the loci in the Japanese sample were not similar to those in samples from other racial or ethnic groups except for the Chinese (for HUMTPOX). The results demonstrate that HUMTH01, HUMTPOX and HUMVWFA31 are more useful for forensic investigations in the Japanese population that the other three loci.

Alleles↗
PubMed1996

Anticoagulant pretreatment attenuates production of cytokine-induced neutrophil chemoattractant following ischemia-reperfusion of rat liver.

We investigated whether anticoagulation would diminish ischemia-reperfusion injury of the liver. Liver ischemia was induced in rats by occluding the portal vein for 30 min. Anticoagulant was injected intravenously 10 min before occlusion. Serum concentrations of cytokine-induced neutrophil chemoattractant (CINC) in untreated rats increased following reperfusion, reaching a peak at 6 hr, then decreasing gradually to control levels by 24 hr. CINC levels in rats pretreated with heparin (50 units/kg), AT-III (250 units/kg), or DEGR-Xa (10 mg/kg) peaked at 3 hr after reperfusion and declined to baseline within 12 hr; peak CINC values were significantly lower than in untreated control rats. Expression of CINC mRNA in liver tissue paralleled the CINC serum levels. Both myeloperoxidase activity and the number of neutrophils in the liver were decreased in the anticoagulant groups. In addition, significant correlations were observed between the maximum values of AST, ALT, and LDH versus the peak CINC levels following ischemia-reperfusion. These results indicate that the release of CINC after ischemia-reperfusion of the liver is mediated by activation of coagulation within the hepatic microcirculation.

Amino Acid Chloromethyl Ketones↗
PubMed1996

A sustained increase in beta-adrenoceptors during long-term therapy with metoprolol and bisoprolol in patients with heart failure from idiopathic dilated cardiomyopathy.

Effects of long-term therapy with beta 1-selective antagonists (metoprolol, bisoprolol) on beta-adrenoceptors in lymphocytes of patients with idiopathic dilated cardiomyopathy (DCM) were examined. There was a significant reduction in the number of lymphocyte beta-adrenoceptors in patients with DCM compared to that in healthy volunteers, as demonstrated by a selective decrease in maximum number of binding sites (Bmax) for (-)-[125I]iodocyanopindolol (CYP). A therapy with metoprolol and bisoprolol in these patients caused a marked increase in lymphocyte beta-adrenoceptor density. The significant increase was observed from 2 or 3 months after the start of therapy with these drugs, and it was maintained during the therapy for 24 months. The left ventricular ejection fraction in patients with DCM was improved by the long-term therapy with metoprolol and bisoprolol, and this effect seems to be correlated with an observed enhancement of lymphocyte beta-adrenoceptors in the time course. Also, the increase in lymphocyte beta-adrenoceptors appears to be correlated with a gradual amelioration in circulating catecholamine levels by the long-term therapy with beta-adrenoceptor antagonists in patients with DCM. Thus, the present study suggests that beta-adrenoceptors in lymphocytes of patients with DCM are up-regulated by a long-term therapy with metoprolol and bisoprolol.

Adrenergic beta-2 Receptor Antagonists↗
PubMed1996

Information theoretic analysis of action potential trains. II. Analysis of correlation among n neurons to deduce connection structure.

We propose a cross-correlational method based on information theory, which produces a network connection structure to account for observed patterns of action potential activity in multi-unit recordings. Firing probabilities and conditional probabilities are estimated from the action potential trains of n neurons. Two-point mutual information (2pMI) and joint conditional mutual information (JCMI) are calculated by using the estimated probabilities, and then the n-point mutual information (npMI) is calculated. A significant peak of npMI indicates that each neuron is connected to all other neurons at specified time differences, either directly or indirectly. To distinguish between direct and indirect connection, the two-point m-joint conditional mutual information (2pJCMI) is calculated over the peak region for each pair of neurons. A minimum effective connection structure among the n neurons can be deduced in this manner. The procedure for deducing the connection structure for three- and n-neuron networks is described. We apply this method to action potential trains produced by simulated neural networks. Some limitations of the method are also discussed.

Action Potentials↗
PubMed1996

Changes of lymphocyte subpopulations in pigs infected with porcine reproductive and respiratory syndrome (PRRS) virus.

Abnormal changes of T-cell subpopulation were observed in the peripheral blood lymphocytes of pigs infected with porcine reproductive and respiratory syndrome (PRRS) virus. Pigs with naturally occurring PRRS revealed increases in CD2+ and CD8+ cells, and decreases in CD4+ cells and the ratios of CD4+/CD8+ cells. Specific-pathogen-free pigs inoculated with PRRS virus showed remarkable decreases in total lymphocytes, CD4+ and CD2+ cells on Postinoculation Day (PID) 3. The decline of CD4+ cells continued for at least 14 days, while CD2+ cells showed a tendency to increase thereafter. On the other hand,CD8+ cells slightly decreased in number on PID 3, and then increased remarkably; their number was significantly larger on PIDs 28 and 35 than on PID 0. The ratios of CD4+/CD8+ cells were significantly low between PIDs 3 and 28 as compared with PID 0. However, there were no differences in thymocyte subpopulations between infected and non-infected pigs, suggesting that the PRRS virus does not modulate intrathymic T-cell differentiation. In an experiment with peripheral blood mononuclear cell cultures, PRRS virus caused neither alteration of T-cell subpopulations nor cell proliferation, suggesting that the virus is not cytotoxic for CD4+ cells and not mitogenic for CD8+ cells.

Animals↗
PubMed1996

Effect of VA-045 on central noradrenergic neuronal system in rats.

1. Administration of VA-045 [2-(nitrooxy)ethyl apovincaminate] and thyrotropin-releasing hormone (TRH) led to improvement in the closed head injury (CHI)-induced neuronal dysfunction such as the loss of righting reflex and disruption of spontaneous movement in rats. 2. The improvement seen with effect of VA-045, but not TRH, was abolished in rats pretreated with N-2-chloroethyl-N-ethyl-2-bromobenzylamine (DSP4), a selective noradrenaline (NA) neurotoxin. DSP4 reduced endogenous NA levels in all central nervous system (CNS) regions analyzed. 3. The extracellular concentrations of NA in the frontal cortex (FC) and in the locus coeruleus (LC) of urethane-anesthetized rats were measured using in vivo microdialysis coupled with high-performance liquid chromatography (HPLC) with electrochemical detection. VA-045 had no effect on extracellular concentrations of NA, in both FC and LC. Perfusion with clonidine, and alpha 2 adrenoceptor agonist, led to inhibition in NA output in both FC and LC, and VA-045 antagonized the effect of clonidine. 4. These findings indicate that the mode of action of VA-045 may be, at least in part, related to central NA neuronal systems.

Animals↗
PubMed1996

Determination of alpha 1-adrenoceptor antagonists in plasma by radioreceptor assay.

A simple, rapid and sensitive radioreceptor assay (RRA) for the quantification of alpha 1-adrenoceptor antagonists such as prazosin in plasma is described. The method involves the use of an RRA based on [3H]prazosin displacement in rat cerebral cortical membranes. The method is reliable, with intra-assay and inter-assay RSDs ranging from 5.9 to 9.2%. The limit of detection is 0.2 (prazosin hydrochloride), 0.05 (tamsulosin hydrochloride) and 0.3 (bunazosin hydrochloride) pmol per assay. Using this method the plasma levels of prazosin hydrochloride were determined in beagle dogs administered orally 2.39 mumol kg-1 of this drug. The plasma levels of prazosin in beagle dogs are in good agreement with those obtained using a high-performance liquid chromatography (HPLC). This RRA proved to be applicable to the monitoring of plasma prazosin levels in patients with essential hypertension and/or benign prostatic hypertrophy receiving therapy with this drug with the therapeutic dosage schedule. Thus, the concentrations of alpha 1-adrenoceptor antagonists in plasma can be adequately monitored by RRA as well as by HPLC.

Adrenergic alpha-1 Receptor Antagonists↗
PubMed1996

Detection of porcine reproductive and respiratory syndrome virus and Mycoplasma hyorhinis antigens in pulmonary lesions of pigs suffering from respiratory distress.

Eleven field cases of a disease characterized by severe dyspnoea or abdominal breathing were examined post mortem. The affected pigs had antibody against porcine reproductive and respiratory syndrome virus (PRRSV). The predominant lung lesions were severe proliferative and interstitial pneumonia, and slight suppurative bronchopneumonia. The lesions were closely associated with the sites at which PRRSV and Mycoplasma hyorhinis antigens were detected. Four of five pigs inoculated with PRRSV developed slight pneumonitis. The fifth animal, which died of severe pneumonitis, yielded a heavy culture of M. hyorhinis. These findings demonstrate that dual infection with M. hyorhinis and PRRSV caused severe pulmonary lesions.

Animals↗