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Biomedical subjects

M Miwa

Publications and source records attributed to M Miwa.

At least 37 records · Page 2Linked to original sources
PubMed2001

[Nursing interagency referral forms are important for cooperation within the nursing profession upon patient transfer from hospital to home care].

The purpose of this study was to clarify factors concerning hospital discharge notification in Shizuoka. The subjects, nurses at 146 hospitals and 93 public health centers or municipal health centers, were surveyed by means of a questionnaire. The data were analyzed by the chi-squared test and multiple logistic linear regression analysis. The results showed that hospital discharge notification was provided by 92.6% of hospitals having a hospital discharge notification form, but only 7.4% of hospitals without such a form. There was a significant difference in hospital discharge notification between hospitals with and without a nursing interagency referral form, indicating that the latter is an important factor in provision of information on transfer of patients from the care of hospital nurses to that of public health nurses (p < 0.001). There were no significant links between providing hospital discharge notification and the number of beds, the existence of a visiting nurse room, the MSW, the examination of nursing assistance methods after discharge, or the notification of hospitalization. These results indicated that the nursing interagency referral form to be important for notification purposes.

Adult↗
PubMed2000

Poly(ADP-ribose) polymerase localizes to the centrosomes and chromosomes.

Poly(ADP-ribose) polymerase (PARP) takes part mainly in regulation of DNA repair, thereby maintaining genomic stability in the nucleus. However, what role PARP plays in mitotic cells is not known. Centrosomes play an important role in maintaining the fidelity of chromosome distribution during cell division. Loss of these functions might cause chromosomal instability and aneuploidy. p53 and BRCA1 were recently found to localize to the centrosome at mitosis. We found that PARP is localized to the centrosomes and the chromosomes at cell-division phase and interphase by indirect immunofluorescence. Furthermore, by analysis of isolated centrosomes PARP protein was found to associate with the centrosomes during mitosis. These data suggest that PARP may be involved in maintenance of chromosomal stability.

Cell Line↗
PubMed2000

Activation of coagulation in C57BL/6 mice given verotoxin 2 (VT2) and the effect of co-administration of LPS with VT2.

To obtain better insight into the pathogenesis of verotoxin-producing Escherichia coli-associated diseases, in this study, we explored the effect of verotoxin 2 (VT2) on coagulation in an animal model. After being given VT2 (50 ng/kg, lethal dose), C57BL/6 mice showed progressively increasing expression of TF mRNA in the kidney and brain and elevated plasma levels of thrombin-antithrombin III complex (TAT), normotest, fibrinogen, and PAI-1 paralleling the disease course over 24 hours; platelet counts were decreased at 48 hours with hemorrhage in the kidney and brain. Co-administration of lipopolysaccharide (LPS, 0.5 mg/kg) with VT2 (50 ng/kg) exhibited more prominant and/or prolonged increase in not only expression of TF and PAI-1 mRNAs in the kidney and brain but also plasma levels of TAT, fibrinogen, and PAI-1 and was associated with more remarkable hemorrhage in the tissues. Although VT2 (5 ng/kg) was not a lethal dose, co-administration of LPS (0.5 mg/kg) with VT2 (5 ng/kg) enhanced the susceptibility to VT2, resulting in more prolonged elevation of TAT levels during the first 24 hours than that in the LPS group and a second elevation at 72 hours, followed by death. Plasma IL-1beta level reached a maximum at 24 hours after VT2 (50 ng/kg) injection prior to the increase in TAT levels, whereas the increase in TNFalpha level immediately after injection was associated with the increase in PAI-1 mRNA. These observations indicate that the activation of coagulation by VT2 may occur through a mechanism different from that used by LPS, since plasma TAT levels rose in the mice immediately after LPS injection and returned to normal over 36 hours.

Animals↗
PubMed2000

Inhibition of rabbit platelet aggregation by nucleoside 5'-alkylphosphates: correlation with inhibition of agonist-induced calcium influx.

We investigated the effects of uridine 5'-alkylphosphates on agonist-induced aggregation, increased intracellular calcium concentration [Ca(2+)](i), and Ca(2+) (Mn(2+)) influx in washed rabbit platelets. Uridine 5'-hexadecylphosphate (UMPC16) and uridine 5'-eicosylphosphate (UMPC20) at a concentration of 1 x 10(-5) M inhibited platelet aggregation induced by platelet-activating factor (PAF), thrombin, arachidonic acid, and ADP. UMPC16 did not cause significant interference in the binding of [(3)H-acetyl]PAF to platelets. The inhibition of PAF-induced platelet aggregation by UMPC16 was dependent upon the addition time; UMPC16 was ineffective at 60 sec when the extracellular calcium uptake reached the maximum level in PAF-stimulated platelets. Furthermore, UMPC16 inhibited guanosine 5'-O-(3-thiotriphosphate)-induced platelet aggregation but did not affect ionophore A23187- and calcium-independent agonist phorbol 12-myristate 13-acetate-induced platelet aggregation. UMPC16 markedly inhibited the Ca(2+) (Mn(2+)) influx induced by PAF and ADP, and partly inhibited the [Ca(2+)](i) increase induced by the receptor-mediated stimulation. On the other hand, UMPC16 did not affect the [Ca(2+)](i) increase and Ca(2+) (Mn(2+)) influx induced by ionomycin. These experiments suggest that inhibition of calcium influx associated with receptor-mediated platelet activation may be involved in the action of UMPC16.

Adenosine Diphosphate↗
PubMed2000

Cloning and expression of rat neutral sphingomyelinase: enzymological characterization and identification of essential histidine residues.

Using cross-species sequence homology, we cloned a cDNA for rat neutral sphingomyelinase (nSMase) composed of 422 amino acids that shares 87.6 and 79.0% identity with the mouse and human forms respectively. The rat nSMase expressed in Escherichia coli catalyzed sphingomyelin hydrolysis at neutral pH in a Mg(2+)-dependent manner, and required Triton X-100, dithiothreitol, and KCl for its full activity. The cloned rat enzyme shares conserved sequences with nSMases from both eukaryotes and prokaryotes. Introduction of single mutations into either of the histidine residues at positions 136 and 272, putative active sites, entirely abolished the activity, supporting a common mechanism for the nSMase family independent of the species. However, mutation in histidine 151, conserved only in eukaryotes, also abolished the activity, suggesting eukaryote-specific control of nSMase linked to this histidine 151. This enzyme also catalyzed the hydrolysis of lyso-platelet activating factor to yield 1-alkylglycerol at a rate that is slightly lower than that with sphingomyelin.

Amino Acid Sequence↗
PubMed2000

Disorders in the immune responses of T- and B-cells in mice administered intravenous verotoxin 2.

To obtain a better insight into the pathogenesis of verotoxin-producing Escherichia coli (VTEC)-associated diseases, we explored the effect of verotoxin 2 (VT2) on the immune response in mice. The distribution of lymphocyte phenotypes and the lymphocyte immune response were examined after intravenous administration of VT2 to mice. Among the peripheral lymphocytes and splenocytes of 4-week-old C57BL/6 mice, there was first of all a decrease in T-cells, which began 24 h after intravenous administration of VT2 (50 ng/kg, lethal dose). The CD4+ cell subpopulations of the peripheral blood and spleen were significantly decreased at 24 h, while the B220+ splenocyte subpopulation was markedly decreased at 45 h after VT2 administration. In the thymus, a decrease in CD4+CD8+ cells was predominantly observed near death. Interestingly, in E. coli lipopolysaccharide (LPS)-responder mouse strains (C57BL/6 and C3H/HeN) cotreated with LPS, the susceptibility to VT2 was enhanced, and the increase in B220+ cells induced by LPS alone was suppressed. Furthermore, splenocytes from C57BL/6 mice treated with VT2 (50 ng/kg) 6-24 h earlier reduced LPS-induced proliferative responses to 50-52% of that in control cells, indicating that the effect of VT2 on the immunoresponse seen in vivo may be negatively exerted on the proliferation of the cells. In addition, the number of splenocytes that produced anti-sheep red blood cell antibody was decreased in mice treated with VT2. These results suggest that VTEC infection may eliminate CD4+ and CD8+ T-cells and B-cells by affecting their survival and proliferative responses, leading to reduced antibody production.

Animals↗
PubMed2000

The design and synthesis of a new tumor-selective fluoropyrimidine carbamate, capecitabine.

To identify an orally available fluoropyrimidine having efficacy and safety profiles greatly improved over those of parenteral 5-fluorouracil (5-FU: 1), we designed a 5-FU prodrug that would pass intact through the intestinal mucisa and be sequentially converted to 5-FU by enzymes that are highly expressed in the human liver and then in tumors. Among various N4-substituted 5'-deoxy-5-fluorocytidine derivatives, a series of N4-alkoxycarbonyl derivatives were hydrolyzed to 5'-deoxy-5-fluorocytidine (5'-DFCR: 8) specifically by carboxylesterase, which exists preferentially in the liver in humans and monkeys. Particularly, derivatives having an N4-alkoxylcarbonyl moiety with a C4-C6 alkyl chain were the most susceptible to the human carboxylesterase. Those were then converted to 5'-deoxy-5-fluorouridine (5'-DFUR: 4) by cytidine deaminase highly expressed in the liver and solid tumors and finally to 5-FU by thymidine phosphorylase (dThdPase) preferentially located in tumors. When administered orally to monkeys, a derivative having the N4-alkoxylcarbonyl moiety with a C5 alkyl chain (capecitabine: 6) The highest AUC and Cmax for plasma 5'-DFUR. In tests with various human cancer xenograft models, capecitabine was more efficacious at wider dose ranges than either 5-FU or 5'-DFUR and was significantly less toxic to the intestinal tract than the others in monkeys.

Administration, Oral↗
PubMed2000

Platelet-activating factor acetylhydrolase gene mutation in Japanese children with Escherichia coli O157-associated hemolytic uremic syndrome.

Platelet-activating factor (PAF) may be involved in the pathogenesis of Escherichia coli O157-associated hemolytic uremic syndrome (HUS). PAF is degraded to inactive products by PAF acetylhydrolase. In this study, we investigated whether a PAF acetylhydrolase gene mutation (G-->T transversion at position 994) is involved in HUS in Japanese children. A point mutation in the PAF acetylhydrolase gene (G994T) was identified using polymerase chain reaction in 50 Japanese children with E coli O157-associated HUS and 100 healthy Japanese. We then determined the relationship between the PAF acetylhydrolase G994T gene mutation and clinical features of HUS. There was no difference in genotype and allele frequencies between patients with HUS and healthy controls. The mean duration of oligoanuria was significantly longer in patients with the GT genotype than in those with the GG genotype (P = 0.012). Although 11 of 15 patients (73%) heterozygous for the mutant allele (GT) required dialysis, only 13 of the 35 wild-type homozygotes (GG; 37%) required dialysis (P = 0. 030). Mean plasma PAF acetylhydrolase activity was significantly less in patients with the GT genotype than in those with the GG genotype (P < 0.0001). In conclusion, we have shown an association between the G994T PAF acetylhydrolase gene mutation and the severity of renal damage in E coli O157-associated HUS. Our study suggests that analysis of the PAF acetylhydrolase gene mutation in Japanese children with E coli O157-associated HUS may allow the prediction of the severity of HUS.

1-Alkyl-2-acetylglycerophosphocholine Esterase↗
PubMed2000

Induction of apoptosis in bovine articular chondrocyte by prostaglandin E(2) through cAMP-dependent pathway.

OBJECTIVE: Regulation of important biological processes such as proliferation and differentiation of articular chondrocytes is known to be mediated by prostaglandin E(2) (PGE(2)) in both normal and pathological states. Articular chondrocytes also undergo apoptosis, a biological phenomenon implicated in many physiological processes. Whether or not PGE(2) induces apoptosis in articular chondrocytes, however, is not known. DESIGN: Bovine articular chondrocytes were cultured with or without PGE(2) for 24 h and amounts of fragmented DNA, which is a distinct characteristic of apoptosis, were measured by enzyme-linked immunosorbent assay. Also effect of cyclic AMP (cAMP), which is one of the intracellular downstream mediator of PGE(2), on chondrocyte apoptosis was investigated. RESULTS: Administration of exogenous PGE(2) on bovine articular cartilage grown as a monolayer culture resulted in the induction of DNA fragmentation. This DNA fragmentation was accompanied with a marked dose-dependent increase in intracellular cAMP. Also cultured cells were treated with cAMP analogue, dibutyryl-cAMP or forskolin, a direct activator of adenylate cyclase, and the incidence of apoptosis in the chondrocytes was determined. As well as PGE(2), dibutyryl-cAMP and forskolin stimulated chondrocyte DNA fragmentation. CONCLUSIONS: It is the first report that PGE(2) can induce articular chondrocyte apoptosis in vitro. It is also suggest that apoptosis of chondrocytes by PGE(2) is linked with cAMP-dependent pathway.

Animals↗
PubMed2000

Involvement of arachidonic acid in chemical stress-induced interleukin-6 synthesis in osteoblast-like cells: comparison with heat shock protein 27 induction.

In a previous study, we have demonstrated that sodium arsenite (arsenite) as chemical stress stimulates heat shock protein 27 (HSP27) induction and arachidonic acid release in osteoblast-like MC3T3-E1 cells, and that the response of HSP27 induction is coupled with metabolic activity of the arachidonic acid cascade. In the present study, we examined the effect of exposure to arsenite on the synthesis of interleukin-6 (IL-6) in these cells. Arsenite induced the synthesis of IL-6 after 6 h from the stimulation up to 48 h. The effect of arsenite on IL-6 synthesis was dose-dependent in the range between 10 and 500 microM. The arsenite-induced IL-6 synthesis was enhanced by the pretreatment with indomethacin, an inhibitor of cyclooxygenase. Nordihydroguaiaretic acid, a lipoxygenase inhibitor, significantly amplified the arsenite-induced IL-6 synthesis. Melittin, an activator of phospholipase A2, which by itself hardly affected the levels of IL-6, markedly enhanced the arsenite-induced IL-6 synthesis. These results strongly suggest that chemical stress induces IL-6 synthesis in osteoblasts, and that the IL-6 synthesis is coupled to the arachidonic acid cascade as well as the HSP27 induction by arsenite.

3T3 Cells↗
PubMed2000

Plasma platelet-activating factor acetylhydrolase deficiency is associated with atherosclerotic occlusive disease in japan.

PURPOSE: Plasma platelet-activating factor acetylhydrolase (PAF-AH) is known to catalyze platelet-activating factor, thereby inactivating its inflammatory function. Deficiency of this enzyme is caused by a missense (G(994)-->T) in exon 9 of the plasma PAF-AH gene. In this study, we investigated a possible association of this mutation with the risk of atherosclerotic occlusive disease (AO) in Japanese patients. METHODS: We studied 104 patients with AO. The control group consisted of 114 subjects matched for age and sex. Plasma PAF-AH activity was measured in the patients with AO. RESULTS: The prevalence of the mutant genotype (GT + TT ) was significantly more frequent in patients with AO than in control subjects (36.5% vs 23.7%; P <.05). Among the patients with AO, those with the mutant allele had significantly more risk factors of prior stroke or ischemic heart disease than patients with normal genotypes. Plasma PAF-AH activity was higher in patients with AO than in control subjects in normal genotype subgroups. CONCLUSIONS: The missense (G(994)-->T) in exon 9 of the plasma PAF-AH gene is associated with AO in Japanese people.

1-Alkyl-2-acetylglycerophosphocholine Esterase↗
PubMed2000

Quantification of ischemic muscle deoxygenation by near infrared time-resolved spectroscopy.

The purpose of this study was to quantify muscle deoxygenation in human skeletal muscles using near infrared time-resolved spectroscopy (NIRTRS) and compare NIRTRS indicators and blood saturation. The forearm muscles of five healthy males (aged 27-32 yrs.) were monitored for changes in hemoglobin saturation (SO2) during 12 min of arterial occlusion and recovery. SO2 was determined by measuring the temporal profile of photon diffusion at 780 and 830 nm using NIRTRS, and was defined as SO2-TRS. Venous blood samples were also obtained for measurements of SvO2, and PvO2. Interstitial PO2(PintO2) was monitored by placing an O2 electrode directly into the muscle tissue. Upon the initiation of occlusion, all parameters fell progressively until reaching a plateau in the latter half of occlusion. It was observed at the end of occlusion that SO2-TRS (24.1 +/- 5.6%) agreed with SvO2 (26.2 +/- 6.4) and that PintO2 (14.7 +/- 1.0 Torr) agreed with PvO2 (17.3 +/- 2.2 Torr). The resting O2 store (oxygenated hemoglobin) and O2 consumption rate were 290 microM and 0.82 microM s-1, respectively, values which reasonably agree with the reported results. These results indicate that there was no O2 gradient between vessels and interstisium at the end of occlusion.

Adult↗
PubMed2000

Bicyclo[3.2.1]octane and 6-oxabicyclo[3.2.2]nonane type neolignans from Magnolia denudata.

From the ethyl acetate soluble fraction of twigs of Magnolia denudata (Magnoliaceae), seven new neolignan derivatives, 1-7, were isolated along with eighteen known lignan and neolignan derivatives, 8-25. The structures of the new neolignans were elucidated by means of spectral methods, especially by 1H-NMR and 13C-NMR spectra, and two dimensional NMR methods such as 1H-detected heteronuculear multiple bond connectivity1 (HMBC), 1H-detected multiple quantum coherence (HMQC) and 1H-1H-correlation spectroscopy (COSY). Compounds 1-4 have novel structures possessing a 6-oxabicyclo[3.2.2]nonane skeleton and compounds 5-8 also have novel structures possessing a bicyclo[3.2.1]octane skeleton. The anti-platelet-activating factor (PAF) activity of these compounds was tested by measurement of inhibition activity against acetyl transferase to lyso-PAF.

Bridged Bicyclo Compounds, Heterocyclic↗
PubMed2000

Application of a single-cell gel electrophoresis (comet) assay to screen the antimutagenic activity in foods.

Three cell lines (HL60, U937 and RAW264.7) were studied for their sensitivity against mutagens by using a single-cell gel electrophoresis (comet) assay. RAW264.7, the most sensitive one, was chosen to screen the antimutagenic activity in swine and bovine offal. Aqueous extracts of the swine stomach (0.2 mg/ml) and heart (10 mg/ml) were found to have antimutagenic activity against MeIQx (+ S9mix)-treated cells.

Animals↗