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Biomedical subjects

H Hayashi

Publications and source records attributed to H Hayashi.

At least 289 records · Page 16Linked to original sources
PubMed2000

Activation of G-protein coupled fMLP or PAF receptor directly triggers glucose transporter type 1 (GLUT1) translocation in Chinese hamster ovary (CHO) cells stably expressing fMLP or PAF receptor.

The chemoattractants, fMLP and PAF, stimulate glucose uptake in phagocytes to obtain an energy source for host defense. Glucose uptake in phagocytes is mainly regulated via glucose transporter type 1 (GLUT1). To examine molecular mechanisms of facilitated glucose uptake in response to fMLP or PAF, we established CHO cells stably expressing fMLP or PAF receptor with c-myc epitope tagged GLUT1 which could immunologically detect GLUT1 on the cell surface. In the CHO cells, both fMLP and PAF directly triggered GLUT1 translocation from the intracellular pool to the cell surface, and stimulated glucose uptake. Therefore, in phagocytes, we propose that fMLP and PAF also trigger GLUT1 translocation to stimulate glucose uptake as an energy source for host defense.

Amino Acid Sequence↗
PubMed2000

Overexpression of wild-type Akt1 promoted insulin-stimulated p70S6 kinase (p70S6K) activity and affected GSK3 beta regulation, but did not promote insulin-stimulated GLUT4 translocation or glucose transport in L6 myotubes.

We have developed a simple, direct and sensitive method to detect GLUT4 on the cell surface. Using this system, we found that PI3-kinase plays a key role in the signaling pathway of insulin-stimulated GLUT4 translocation. One of the down stream effectors of PI3-kinase is serine-threonine kinase Akt (protein kinase B, RAK-PK), but the involvement of Akt in insulin-stimulated GLUT4 translocation is controversial. To investigate whether Akt1 regulates insulin-stimulated GLUT4 translocation and glucose uptake in L6 myotubes, we established L6 myotubes stably expressing c-myc epitope-tagged GLUT4 (GLUT4myc) and mouse wild type (WT) Akt1. We found that overexpression of WT Akt1 promoted insulin-stimulated p70S6 kinase (p70S6K) activity and increased the basal activity of GSK3 beta, but did not promote insulin-stimulated GLUT4 translocation or glucose uptake. These data supported the result that Akt is not a main signaling molecule to transmit the signal of insulin-stimulated GLUT4 translocation or glucose uptake from insulin-activated PI3-kinase.

Amino Acid Sequence↗
PubMed2000

[Esophageal dilation therapy for achalasia of the esophagus].

Esophageal dilation therapy for esophageal achalasia has a 300-year history and remains the first-line therapy because of its low cost, progressively decreasing morbidity and mortality, and possibility of surgery for patients who do not improve. Another advantage is the feasibility of repeated trial even after surgery. The aim of this procedure is to produce a controlled tear in the lower esophageal sphincter muscle. Precise esophagographic, endoscopic, and manometric diagnosis is necessary for successful esophageal dilation therapy. In addition, the exclusion of pseudoachalasia using echogram or CT scan is important. The procedure should be carried out accurately to prevent complications. If perforation occurs, appropriate, timely management is required.

Catheterization↗
PubMed2000

[Refraction and anterior chamber depth change after vitrectomy for pseudophakia].

PURPOSE: To evaluate the association between the vitreous and the refractive error in pseudophakia. METHODS: Vitrectomy was performed in 67 eyes of 61 patients who underwent cataract surgery. Vitrectomy was needed for epiretinal membrane in 30 eyes, macular edema in 22 eyes, macular hole in 3 eyes, lamelar macular hole in 2 eyes, vitreous opacity in 6 eyes, and vitreous hemorrhage in 4 eyes. Refraction was measured before the operation, and 1 month, 3 months, 6 months, and 12 months after operation. Anterior chamber depth was measured in 10 eyes before the operation, and 1 month, 3 months, and 6 months after operation. We evaluated the refractive error after vitrectomy in 49 eyes that had predicted refraction. RESULTS: The mean value of refractive change was -0.3 D 1 month postoperatively, and then gradually became positive. The variation of refraction (6-month postoperative refraction minus preoperative refraction) was negatively correlated with preoperative refraction (p = 0.0052, R2 = 0.146). If preoperative refraction was more myopic than -1.5 D, then refraction became positive. If preoperative refraction was not more myopic than -1.5 D, then refraction became negative. CONCLUSION: About 15% of postoperative refractive error may be associated with the vitreous, but further investigation is required.

Aged↗
PubMed2000

Epidemiological analysis of methicillin resistant Staphylococcus aureus in Thailand.

The geographical distribution of 65 clinical isolates of methicillin resistant Staphylococcus aureus (MRSA) recovered from 7 hospitals in Thailand was investigated. The presence of mecA gene in MRSA was determined by specific PCR with the use of primers 5'-GTAGTTGTCGGGTTTGGT-3' and 5'-GGTATCATCTTGTACCCA-3'. Chromosomal DNA restriction analysis with SmaI was resolved by pulsed-field gel electrophoresis (PFGE) compared with antibiotype analysis and phage type analysis. All 65 strains carried mecA gene. They all were resistant to penicillin, tetracycline, erythromycin, amoxicillin/clavulanic acid and variably resistant to gentamicin, ofloxacin, trimethoprim-sulfamethoxazole, chloramphenicol, fosfomycin and clindamycin; and all isolates were susceptible to vancomycin. A total of 19 PFGE patterns designated as type A, A1, A2, A3, A4, B, B1, C, D, E, E1, E2, F, F1, F2, G, H, I and J was identified. Type A4 and E were commonly found in every studied areas. Phage typing showed even greater variability that 52 (80%) isolates belonged to 25 different phage types; 13 (20%) isolates were non-typable. The clarity and polymorphism of the PFGE patterns enable us to discriminate between isolates which could not be differentiated by antibiogram or phage type analysis. The findings demonstrate the existence of a common epidemic MRSA clone in Thailand.

Bacterial Typing Techniques↗
PubMed2000

Role of cardiac renin-angiotensin system in sarcoplasmic reticulum function and gene expression in the ischemic-reperfused heart.

The aim of this study was to explore the possible participation of cardiac renin-angiotensin system (RAS) in the ischemia-reperfusion induced changes in heart function as well as Ca2+-handling activities and gene expression of cardiac sarcoplasmic reticulum (SR) proteins. The isolated rat hearts, treated for 10 min without and with 30 microM captopril or 100 microM losartan, were subjected to 30 min ischemia followed by reperfusion for 60 min and processed for the measurement of SR function and gene expression. Attenuated recovery of the left ventricular developed pressure (LVDP) upon reperfusion of the ischemic heart was accompanied by a marked reduction in SR Ca2+-pump ATPase, Ca2+-uptake and Ca2+-release activities. Northern blot analysis revealed that mRNA levels for SR Ca2+-handling proteins such as Ca2+-pump ATPase (SERCA2a), ryanodine receptor, calsequestrin and phospholamban were decreased in the ischemia-reperfused heart as compared with the non-ischemic control. Treatment with captopril improved the recovery of LVDP as well as SR Ca2+-pump ATPase and Ca2+-uptake activities in the postischemic hearts but had no effect on changes in Ca2+-release activity due to ischemic-reperfusion. Losartan neither affected the changes in contractile function nor modified alterations in SR Ca2+-handling activities. The ischemia-reperfusion induced decrease in mRNA levels for SR Ca2+-handling proteins were not affected by treatment with captopril or losartan. The results suggest that the improvement of cardiac function in the ischemic-reperfused heart by captopril is associated with the preservation of SR Ca2+-pump activities; however, it is unlikely that this action of captopril is mediated through the modification of cardiac RAS. Furthermore, cardiac RAS does not appear to contribute towards the ischemia-reperfusion induced changes in gene expression for SR Ca2+-handling proteins.

Animals↗
PubMed2000

[Three cases of severe hyponatremia under taking selective serotonin reuptake inhibitor (SSRI)].

The association between selective serotonin reuptake inhibitors(SSRIs) and hyponatremia has been documented throughout the world. In Japan, since SSRIs have recently come into use for patients with depression, there are only a few reports of hyponatremia associated with SSRIs. We present here three cases of the syndrome of inappropriate secretion of antidiuretic hormone(SIADH) associated with the administration of fluvoxamine for depression. They were admitted to our hospital because of deep coma, and revealed severe hyponatremia. Their serum sodium levels were 103-112 mEq/l, serum osmolalities were 227-241 mmol/kg, urine sodium levels were 38-107 mEq/l, and urine osmolalities were 352-781 mmol/kg. These patients were started on fluvoxamine 3 days-3 months previously. The diagnosis of SIADH in these patients was made based on hyponatremia, and low serum and high urine osmolalities. The fluvoxamine treatment was discontinued, and hypertonic saline was infused. Their serum sodium levels and osmolalities were subsequently normalized. None of the other known causes of hyponatremia, including diuretic therapy, tumors, and respiratory and central nervous system diseases, were present. High plasma AVP levels observed in the two cases suggest that SSRIs stimulate AVP secretion, thereby causing SIADH. Many reports have shown that people older than 70 years were at a particularly high risk of developing hyponatremia when SSRIs were used. In the future, since the use of SSRIs will be increasing, the water and electrolyte balance of elderly patients should be monitored carefully during SSRIs therapy.

Aged↗
PubMed2000

Pathogenesis and the role of Ca2+ overload during myocardial ischemia/reperfusion.

To study the regulation of [Na+]i and [Ca2+]i during myocardial ischemia/reperfusion, [Na+]i and [Ca2+]i were measured simultaneously using guinea pig ventricular myocytes which were dual-loaded with SBFI/AM and fluo-3/AM. It was suggested that: (1) [Na+]i increased during metabolic inhibition (MI: 3.3 mM amytal and 5 microM CCCP) by both the activated Na+ influx via Na+/H+ exchange and the suppressed Na+ extrusion via the Na+/K+ pump; (2) Na+/Ca2+ exchange was inhibited during MI, causing the dissociation between [Na+]i and [Ca2+]i; (3) Na+/Ca2+ exchange could be reactivated by energy repletion, resulting in a significant increase in [Ca2+], Furthermore, a Ca2+ influx via the reverse-mode of Na+/Ca2+ exchange may play a key role in the mechanism of Ca2+ overload on reoxygenation; and (4) cell contracture during MI was related to rigor due to energy depletion, while cell contracture after energy repletion was likely to be related to Ca2+ overload.

Animals↗
PubMed2000

1-Methyl-3-isobutylxanthine delays apoptosis induced by deprivation of growth factors in vascular endothelial cells.

AIM: To investigate the effects of 1-methyl-3-isobutylxanthine (MIBX) on apoptosis induced by deprivation of acidic fibroblast growth factor (aFGF) and serum in vascular endothelial cells (VEC). METHODS: Nuclear fragmentation was observed by fluorescence microscopy. Viability was determined by counting the cells that attached to dishes after treatments. DNA fragmentation was measured by agarose gel electrophoresis. RESULTS: The cells deprived of aFGF and serum were treated with MIBX 25-200 mumol/L for 3, 6, 9, and 12 h, respectively. Morphological changes including the formation of apoptotic bodies and DNA fragmentation of these cells were significantly suppressed by IBMX 50-200 mumol/L at 3 h and 6 h. But after 12-h treatment, no difference was observed between the treated and untreated cells. CONCLUSION: MIBX delays apoptosis of vascular endothelial cells induced by deprivation of aFGF and serum.

1-Methyl-3-isobutylxanthine↗
PubMed2000

Trichinella spiralis-specific monoclonal antibodies and affinity-purified antigen-based diagnosis.

Hybridomas secreting monoclonal antibodies (MAbs) to Trichinella spiralis were produced. Myeloma cells were fused with splenocytes of a mouse immunized with excretory-secretory (E-S) antigen of infective larvae. A large percentage of growing hybrids secreted antibodies cross-reactive to many of 23 heterologous parasites tested. Only 6 monoclones (designated 3F2, 5D1, 10F6, 11E4, 13D6 and 14D11) secreted MAbs specific to the E-S antigen and/or a crude extract (CE) of T. spiralis infective larvae. The 6 monoclones secreted IgM, IgG3, IgM, IgG3, IgG3 and IgG3, respectively. Clone 5D1 was selected to mass produce MAbs which were then coupled to CNBr-activated Sepharose CL-4B to prepare an affinity-purified antigen. Dot-blot ELISA with either purified antigen or CE was evaluated. There were 17 patients with acute trichinellosis and 76 individuals convalescing from T. spiralis infection (group 1). Controls were 170 patients with parasitic infections other than trichinellosis (group 2) and 35 healthy parasite-free controls (group 3). CE-ELISA was positive in all group 1 patients. However, sera from many group 2 patients also were reactive (opisthorchiasis-44.2%, schistosomiasis-44%, gnathostomiasis-30%, paragonimiasis-28.6%, taeniasis-27.3%, strongyloidiasis-23.1% and hookworm infections-20%). Affinity-purified antigen was 100% specific, all sera from group 2 and group 3 individuals tested negative. Although 74 of 76 patients (97.4%) with convalescing trichinellosis tested positive, sera from only 3 of 17 patients (17.6%) with acute T. spiralis were reactive. Thus, CE antigen is appropriate when sensitivity is needed, while purified antigen should be used when specificity is required. Dot-blot ELISA is easier to perform, more rapid and less expensive than indirect ELISA. Many samples can be assayed simultaneously, special equipment is not required, and results can be preserved for retrospective analysis. Dot-blot ELISA is therefore the method of choice for the rapid diagnosis of trichinellosis, particularly when more complex laboratory tests are unavailable.

Animals↗
PubMed1999

Expression of the mRNA for two isoforms of neural plakophilin-related arm-repeat protein/delta-catenin in rodent neurons and glial cells.

Neural plakophilin-related arm-repeat protein (NPRAP) is a mammalian brain protein of the armadillo family. Here, in an attempt to elucidate its function, we determined the mouse brain regions and cell types expressing the mRNAs for two NPRAP isoforms (the longer and the shorter isoforms), and examined the regulation of expression of the NPRAP mRNAs during the differentiation of P19 cells into neurons. Reverse transcription-polymerase chain reaction (RT-PCR) analysis revealed that both variants were expressed in various mouse brain regions, but the mRNA for the short isoform was predominant in most regions. Primary cultures of both neurons and glial cells exhibited high expression levels of both the mRNAs, indicating that NPRAP mRNA expression is not neuron-specific. The expression of the two NPRAP mRNA variants was dramatically induced even prior to the terminal neuronal and glial differentiation of P19 cells after retinoic acid treatment. These data suggest that the two NPRAP isoforms function not only in neurons and glial cells in the brain, but also play a role in the differentiation of precursor cells into neurons and glial cells.

Animals↗
PubMed1999

Interdependence of Anion and Cation Exchanges in Calcium Hydroxyapatite: Pb(2+) and Cl(-).

The ion exchange of Pb(2+) and Cl(-) into calcium hydroxyapatite from aqueous solutions is studied at 293 K. Although the exchange of Cl(-) into CaHAp and PbHAp was not observed, in the presence of both Pb(2+) and Cl(-) in aqueous solution the exchange of both Pb(2+) and Cl(-) into CaHAp occurred, and, at least at intermediate concentrations of HCl, a proportionality between the sorbed quantities of these two ions was observed. The dissolution of CaHAp is shown to be dependent upon the pH, while the quantity of Pb(2+) exchanged into the solid is not a function of the proton content; consequently, the exchange is not primarily a dissolution-precipitation process. Copyright 1999 Academic Press.

Journal Article↗
PubMed1999

Study on the concentration of circulating primordial germ cells (cPGCs) in early chick embryos.

Experiments were conducted to elucidate the factor that influences the concentration of circulating primordial germ cells (cPGCs) in two-day old chick embryos. The concentration of cPGCs was observed to be highest at stage 14 (66.9 +/- 23.2 microliters) and decreased thereafter. However, considerable egg to egg variations in cPGC concentration, especially at stages 13, 14, 15, and 16 were observed. After conducting experiments to elucidate the source of egg to egg variation in cPGC concentration among embryos, it was revealed that there are hens that lay eggs which contain either constantly high (more than 80 PGCs/microliter) or constantly low (less than 30 PGCs/microliter) concentration of cPGCs. The results obtained from the present experiments showed that one of the major source of egg to egg variation in the concentration of cPGCs was due to the individual differences among females that produced the eggs.

Animals↗
PubMed1999

Association of stomatin (band 7.2b) with Glut1 glucose transporter.

Employing a monoclonal antibody directed against the C-terminal peptide of glucose transporter molecule 1 (Glut1), we identified a approximately 30-kDa polypeptide which coimmunoprecipitated with Glut1 from sample of human red blood cells (RBC) membranes. The approximately 30-kDa polypeptide reacted with an antibody directed against stomatin, an integral plasma membrane protein which is also present at a high abundance in the human RBC plasma membrane. Likewise, employing anti-stomatin antibody, we found that Glut1 coimmunoprecipitated with stomatin from samples of RBC membranes. However, neither band 3, which is the most abundant integral membrane protein in the RBC, nor actin coimmunoprecipitated with Glut1, indicating a specific interaction between Glut1 and stomatin. Similar to the results obtained in the RBC, Glut1 and stomatin immunoprecipitated with each other in lysates of Clone 9 cells, a rat liver cell line in which Glut1 is expressed at approximately 1/200 the level present in RBC. Employing conditions that resulted in immunoprecipitation of approximately 10% of Glut1 in RBC membranes led to a approximately 3% coimmunoprecipitation of stomatin. A mixed population of Clone 9 cells stably transfected with a plasmid overexpressing the mouse stomatin exhibited 30 +/- 3% reduction in the basal rate of glucose transport compared to control cells or cells stably transfected with the empty vector. The above results suggest that stomatin is closely associated with Glut1 in the plasma membrane and that overexpression of stomatin results in a depression in the basal rate of glucose transport.

Animals↗