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Biomedical subjects

M Yoshida

Publications and source records attributed to M Yoshida.

At least 235 records · Page 13Linked to original sources

Effect of salicylate and short-term sound exposure on extracochlear electrically-evoked otoacoustic emissions.

The effects of salicylate and acoustic overstimulation on the electromotility of the cochlear outer hair cells (OHCs) were assessed in vivo using electrically-evoked otoacoustic emissions (EEOAEs). Alternating currents to evoke the EEOAE were delivered by means of an extracochlear electrode on the round window, with which the compound action potentials (CAPs) were also monitored before and after the manipulations. The EEOAE outputs were a linear function of the injected currents between 52 and 267 microA rms. Administration of salicylate (500 mg/kg) reduced the EEOAE outputs significantly at 5 and 8 kHz (p < 0.005). while no change in EEOAEs was observed at any frequency after exposure to a 4 kHz pure tone at 100 dB SPL for 10 min or at 120 dB SPL, for 30 min. These results indicate that administration of salicylate reduces the electromotility of the OHCs, and thus produces losses in neural sensitivity of the cochlea. In contrast, the electromotility of OHCs appears to be protected against short-term intense sound exposure.

Acoustic Stimulation↗

Two distinct mechanisms are involved in stent thrombosis under flow conditions.

The mechanism of stent thrombosis was evaluated by a flow chamber model. A Palmaz-Schatz stent was placed on glass surfaces coated with type I collagen in a parallel-plate flow chamber. Platelets were rendered fluorescent with mepacrine and whole blood was perfused through the chamber. Platelet thrombi formed around the implanted stents were continuously recorded by epi-fluorescent video-microscopy. Platelet thrombi appeared on the collagen surface within a few minutes in the absence of function blocking monoclonal antibodies. Antibody blocking vWF interaction with GP Ib alpha completely inhibited the platelet thrombi around the stent, but had no effect on platelet thrombus formation in the space between the stents and collagen, while both were inhibited by anti-GP IIb/IIIa. Our results suggest that two distinct mechanisms, one mediated by vWF interaction with GP Ib alpha occurring at high shear rates, and the other mediated exclusively by GP IIb/IIIa occurring at low shear rates, are involved in the process of platelet thrombus formation in the presence of stents.

Animals↗

Intragastric endoscopic mucosal resection through a temporary gastrostomy for early gastric cancer: usefulness of Buess-type endoscope.

OBJECTIVE: To assess the feasibility of cure of early gastric cancer by the endoscopic procedure done through a temporary gastrostomy and to use it to treat patients with various severe complications. DESIGN: Prospective study. SETTING: University hospital, Japan. SUBJECTS: Four patients who required gastric mucosal resection for early gastric cancer. MAIN OUTCOME MEASURES: Ease of the procedure, cure rate, safety under epidural anaesthesia, and outcome. RESULTS: All patients had the procedure under epidural anaesthesia without pain or complaints during operation. Mean operation time was 120 minutes (60-200). Histological examination showed that the surgical margin was free of tumour in 3 of the cases. One patient who had microscopic invasion of lymph nodes subsequently underwent second-look conventional gastrectomy with lymphadenectomy. Postoperative recovery was rapid, and all patients were discharged from the hospital uneventfully. CONCLUSION: This organ-preserving procedure enables good visualisation of the tumour and is useful even for high-risk patients.

Adult↗

Postoperative chemoendocrine therapy for women with node-positive stage II breast cancer with combined cyclophosphamide, tamoxifen, and 1-hexylcarbamoyl-5-fluorouracil.

OBJECTIVE: To find out whether the addition of 1-hexylcarbamoyl-5-fluorouracil to a postoperative regimen of oral cyclophosphamide and tamoxifen improved the prognosis of carcinoma of the breast. DESIGN: Randomised controlled clinical trial. SETTING: 127 Institutions in Japan. SUBJECTS: 785 Patients with stage II carcinoma (palpable axillary nodes) who had total mastectomy and axillary clearance. INTERVENTIONS: The control group were given oral cyclophosphamide 50 mg/day and tamoxifen 20 mg/day for 2 years; the experimental group were given these drugs plus 1-hexylcarbamoyl-5-fluorouracil 300 mg/day for 2 years. RESULTS: There was no survival advantage (and more toxicity) in the experimental group, except in a subgroup with 1-3 axillary nodes involved. CONCLUSION: The advantage of triple chemotherapy in the subgroup must be substantiated by a new randomised trial confined to patients with 1-3 axillary nodes involved.

Administration, Oral↗

Release behavior of ketoprofen from poly(acryloyl-L-proline methyl ester) gels having different crosslinked networks.

In order to clarify the relationship between the crosslinked structure of thermo-responsive polymer and drug release profile, polymer gels based on acryloyl-L-proline methyl ester (A-ProOMe) were synthesized in a mixture of water and acetone by the following two methods: a simultaneously occurring process of radiation-induced polymerization and crosslinking without a crosslinker (self-bridging method), and radiation-induced polymerization in the presence of the crosslinker tetradecaethylene glycol dimethacrylate (crosslinker method). The pronounced gap in thermo-response between two A-ProOMe gels, with an apparent degree of crosslinking of 11 for 1-propanol, shows a different shrinking pattern in the initial stage of time. The gels, which were obtained with the self-bridging method and the crosslinker method, were kept constant at a swelling ratio of 17 in water at 0 degree C for all systems. However, those values fell to 0.5 and 4, respectively, at 10 min after the temperature was increased to 37 degrees C. The release mechanism of ketoprofen from two gel devices showed an anomalous (non-Fickian) transport, in which the release of ketoprofen with a low water-solubility could be directly related to the rapid release of water accompanying a gel shrinkage.

Anti-Inflammatory Agents, Non-Steroidal↗

CD4 T cells monospecific to ovalbumin produced by Escherichia coli can induce colitis upon transfer to BALB/c and SCID mice.

Although some animal models suggest an involvement of CD4 T cells reactive to luminal microbial antigen(s) for the pathogenesis of inflammatory bowel diseases (IBD), direct linkage between microflora-driven clonal expansion of CD4 T cells and the development of colitis has not been well studied. Here, BALB/c and SCID mice were given CD4 T cells purified from Rag-2(-/-) mice crossed to transgenic mice expressing TCR specific to ovalbumin (OVA) then administered with antibiotic-resistant Escherichia coli producing OVA (ECOVA) or LacZ (ECLacZ) via the rectum. The ECOVA-inoculated BALB/c and SCID mice developed a subacute colitis with microscopic features of distortion of crypt architecture, loss of goblet cells, and focal infiltration by mononuclear cells in the lamina propria (LP) and submucosa. Expanding OVA-specific CD4 T cells were detected in colonic follicles of mice with ECOVA. Early in colitis, OVA-specific CD4 T cells producing IFN-gamma predominate in the LP of the colon, which was followed by an emergence of OVA-specific CD4 T cells producing IL-4 and IL-10 at a later time point. Co-transfer of an IL-10-secreting OVA-specific CD4 T cell line prevented colitis. Thus, an expansion of CD4 T cells monospecific to OVA, an antigen non-cross-reactive to colonic tissue, can mediate both induction and inhibition of the colitis which was associated with hyperplasia of lymph follicles.

Administration, Rectal↗

Budding of fowlpox and pigeonpox viruses at the surface of infected cells.

Chick embryo fibroblasts and chorioallantoic membranes infected with fowlpox virus (FWPV) or pigeonpox virus (PPV) were examined by transmission and scanning electron microscopy. Immature virus particles were observed in finely granular areas, i.e. virus factories, of the cytoplasm. These particles had various forms depending on their stages of development. Many tubular structures were also seen in these regions. Mature virus particles with ellipsoidal or brick-shaped forms enclosing electron-dense cores were detected throughout the cytoplasm. Notably, there was a high frequency of virus budding at the cell surface, but only occasional virus wrapping in the cytoplasm. Another remarkable feature of the infected cells was accumulation of many virions just beneath the plasma membrane, indicating that this phenomenon is closely related to virus budding. Based on the observed frequency of budding, this mechanism seems to be the predominant way for FWPV and PPV to exit the cell.

Animals↗

Nitric oxide increases matrix metalloproteinase-1 production in human uterine cervical fibroblast cells.

Since uterine cervical ripening is an active biochemical process similar in part to an inflammatory reaction, nitric oxide (NO) has been proposed as a key mediator of this event. However, the mechanism by which NO modulates human cervical ripening has not been fully elucidated. In the present study we investigated the presence of NO synthases in human uterine cervix by immunohistochemistry and reverse transcriptase-polymerase chain reaction analysis. Furthermore, we examined the presence of NO-mediated regulation of matrix metalloproteinase-1 (MMP-1) production in cultured human uterine cervical fibroblast cells using enzyme-linked immunosorbent assay and Northern blot analysis. Endothelial and inducible NO synthases were detected in the form of mRNA and protein expression in pregnant uterine cervix. Interleukin-1alpha (IL-1alpha) increased the expression of inducible NO synthase mRNA in cultured human uterine cervical fibroblast cells. IL-1alpha also increased MMP-1 secretion from the cultured cervical fibroblast cells. This IL-1alpha-augmented MMP-1 secretion was partially but significantly blocked by an NO synthase inhibitor, N(G)-nitro-L-arginine methyl ester. On the other hand, NO donors increased MMP-1 production in the cultured cervical fibroblast cells. These findings together suggest that NO contributes to the process of cervical ripening via enhancement of MMP-1 production, and that IL-1alpha increases MMP-1 secretion from cervical fibroblasts at least in part via NO synthesis.

Basic Helix-Loop-Helix Proteins↗

HMG box A in HMG2 protein functions as a mediator of DNA structural alteration together with box B.

Nonhistone protein HMG2, like HMG1, binds with B-DNA in a sequence-nonspecific manner and causes structural alterations in DNA such as bending, kinking and unwinding. Here, we studied the functions of HMG2 domains in the DNA structural alteration and modulation by using various HMG2 peptides, and we demonstrated several new findings. The HMG box itself as a DNA-binding motif may have the basic function of inducing curvature, resulting in the apparent DNA bending in the DNA cyclization assay, but not of abruptly kinking DNA. The DNA-binding activity of HMG box B, which is enhanced by the presence of box A, together with the flanking regions of box B, causes DNA bending accompanying the kinking of the DNA main chain. The DNA unwinding accompanied by DNA kinking diminishes cruciform structures in supercoiled DNA. Analysis using mutant peptides for box A confirmed that box A in HMG2 functions as a mediator of DNA structural alteration together with box B. The present studies on the functional properties of the respective regions of HMG2 may help to elucidate the protein function.

Amino Acid Motifs↗

Functions and ATP-binding responses of the twelve histidine residues in the TF1-ATPase beta subunit.

The C2 proton signals of all (twelve) histidine residues of the TF1 beta subunit in the 1H-NMR spectrum have been identified and assigned by means of pH change experiments and site-directed substitution of histidines by glutamines. pH and ligand titration experiments were carried out for these signals. Furthermore, the ATPase activity of the reconstituted alpha3beta3gamma complex was examined for the twelve mutant beta subunits. Two of three conserved histidines, namely, His-119 and 324, were found to be important for expression of the ATPase activity. The former fixes the N-terminal domain to the central domain. His-324 is involved in the formation of the interface essential for the alpha3beta3gamma complex assembly. The other conserved residue, His-363, showed a very low pK(a), suggesting that it is involved in the tertiary structure formation. On the binding of a nucleotide, only the signals of His-173, 179, 200, and 324 shifted. These histidines are located in the hinge region, and its proximity, of the beta subunit. This observation provided further support for the conformational change of the beta monomer from the open to the closed form on the binding of a nucleotide proposed by us [Yagi et al. (1999) Biophys. J. 77, 2175-2183]. This conformational change should be one of the essential driving forces in the rotation of the alpha3beta3gamma complex.

Adenosine Triphosphate↗

Efficient folding of the insect neuropeptide eclosion hormone by protein disulfide isomerase.

Eclosion hormone is an insect neuropeptide that consists of 62 amino acid residues including three disulfide bonds. We have previously reported its hypothetical 3D structure consisting mainly of three alpha-helices. In this paper, we report the effects of chaperone proteins on the refolding of denatured eclosion hormone in a redox buffer containing reduced and oxidized glutathione. Urea-denatured eclosion hormone was spontaneously reactivated within 1 min with a yield of more than 90%, while beta-mercaptoethanol-denatured eclosion hormone was reactivated in a few minutes with a yield of 75%. Under the same experimental conditions, eclosion hormone treated with beta-mercaptoethanol and urea was reactivated slowly with a yield of 47% over a period of 2 h. Protein disulfide isomerase, a eucaryotic chaperone protein, markedly increased the reactivation yield and rate of the totally denatured hormone. GroE oligomers slightly improved the reactivation yield but peptidyl prolyl isomerase had no influence on yield or rate. We propose that the folding pathway of eclosion hormone involves at least two rate-limiting steps, and that protein disulfide isomerase is likely to be involved in the folding in insect neuronal cells.

Animals↗

Exposure of neonatal female rats to p-tert-octylphenol disrupts afternoon surges of luteinizing hormone, follicle-stimulating hormone and prolactin secretion, and interferes with sexual receptive behavior in adulthood.

The present study investigated the effects of exposure of neonatal female rats to p-tert-octylphenol (OP) on estrogen-induced afternoon surges of LH, FSH, and prolactin (PRL) secretion, and on sexual behavior in adulthood. After birth, one group of female Wistar rat pups received s.c. injections of OP (100 mg/kg body weight [BW]; OP group) dissolved in DMSO, while the control group received DMSO only (DMSO group). In order to make a qualitative comparison, a third group was injected with estradiol-17beta (500 microg/kg BW; estradiol group) dissolved in DMSO. Injections were given on Days 1, 3, 5, 7, 9, 11, 13, and 15 of age. The rats from the OP and estradiol groups that were used for subsequent experiments were in persistent vaginal estrus. Spontaneous LH surge measured at Postnatal Days (PND) 78-81 was observed only in the DMSO group on the afternoon of the day of proestrus. At PND 115, randomly selected rats from each of three treatment groups were bilaterally ovariectomized (ovx), and 8 days later, Silastic capsules containing estradiol-17beta were implanted under the skin. Estrogen implants stimulated afternoon surges of LH, FSH, and PRL for two consecutive days in the DMSO group, but not in the OP and estradiol groups. Rats from the OP and DMSO groups underwent ovx at PND 186, and 6 days later they were treated with a combination of estradiol benzoate s.c. (15 microg/kg BW) and progesterone s.c. (2 mg/kg BW) to test the lordosis reflex. In response to this hormone treatment and mounting stimulus delivered by the stud male rats, the OP-treated rats were less receptive compared with control DMSO-treated rats, and thus the lordosis quotient and lordosis rating were significantly (P < 0.05) reduced in the OP group compared with the DMSO group. Analysis of the area of the sexually dimorphic nucleus of the preoptic area of the brain revealed that the area of this nucleus was larger in the OP group than it was in control DMSO rats. We conclude that the exposure of neonatal female rats to higher doses of OP disrupts the cyclic release of LH, FSH, and PRL, and interferes with the display of sexual receptive behavior in adulthood.

Aging↗

Cardiovascular responses to the induction of mild hypothermia in the presence of epidural anesthesia.

BACKGROUND: The combining of epidural anesthesia with general anesthesia impairs central and peripheral thermoregulatory control and therefore is often accompanied by unintended intraoperative hypothermia. However, little is known about the cardiovascular response to hypothermia during combined epidural and general anesthesia. The authors assessed the effects of hypothermia during such combined anesthesia. METHODS: The authors randomly assigned 30 mongrel dogs anesthetized with isoflurane (1.0%) to three groups of 10: control, receiving general anesthesia alone; thoracic injection, additionally receiving thoracic epidural anesthesia; and lumbar injection, additionally receiving thoracolumbar epidural anesthesia. Core temperature was lowered from 38.5 degrees C to approximately 34 degrees C (mild hypothermia) using a femoral arteriovenous shunt in an external cool water bath. During hypothermia, the authors measured heart rate, cardiac output, and plasma catecholamine concentrations in each group. Ejection fraction was also measured using echocardiography. RESULTS: Compared with measurements during baseline conditions (general anesthesia alone with no epidural injection and no hypothermia) in the control, thoracic, and lumbar injection groups, the injections followed by hypothermia produced 17, 32, and 41% decreases in heart rate; 22, 32, and 47% reductions in cardiac output; 66, 85, and 92% decreases in the epinephrine concentrations; and 27, 44, and 85% decreases in the norepinephrine concentrations. In contrast, ejection fraction did not change in any group. CONCLUSION: Mild hypothermia during combined epidural anesthesia and general anesthesia markedly reduced cardiac output in dogs, mainly by decreasing heart rate.

Anesthesia, Epidural↗

Lysophosphatidylcholine induces apoptosis in AR42J cells.

Phospholipase A2 (PLA2) has been suggested to play an important role in the pathogenesis of acute pancreatitis, in part through the PLA2-generated phospholipid by-products, most notably lysophosphatidylcholine (lyso-PC). The effects of lyso-PC on pancreatic acinar cells, other than the induction of necrosis, are poorly characterized. Here we examined the effects of lyso-PC on the induction of apoptosis in rat pancreatic AR42J cells. Lyso-PC induced apoptosis in a dose-dependent manner at 10 and 25 microM, but induced cell lysis at > or = 50 microM. Lyso-PC-induced (at 25 microM) apoptosis was not blocked by a protein kinase C inhibitor (staurosporine) or by inhibitors of caspases (acetyl-DEVD-aldehyde and benzoyloxycarbonyl-VAD-fluoromethylketone). Lyso-PC at 10 and 25 microM induced the expression of clusterin mRNA and wild-type p53. Apoptosis induction by lyso-PC (at 25 microM) was not inhibited by a specific antagonist of platelet-activating factor (PAF) receptor, suggesting that the action was independent of th

Animals↗

Gynecologic malignancies accompanied by benign hormone-dependent diseases.

OBJECTIVE: To investigate the correlation between benign gynecologic diseases and hormone-dependent malignancies such as endometrial carcinoma in postmenopausal women. DESIGN: We retrospectively analyzed the prevalence of myoma uteri and adenomyosis uteri in 136 cases of endometrial carcinomas. We used 222 uterine prolapse cases as controls. RESULTS: The results showed that 21.6% and 9.9% of healthy postmenopausal women (control) had myoma uteri and adenomyosis uteri, respectively, after the cessation of menses. However, postmenopausal women with endometrial carcinomas had a 1.5- to 2-fold higher prevalence, respectively, for myoma uteri and adenomyosis uteri as compared with the postmenopausal control women. CONCLUSION: There was a higher prevalence of myoma uteri and adenomyosis uteri in postmenopausal patients with endometrial carcinomas than in the control population.

Aged↗

Pregnancy complicated with Bartter's syndrome: a case report.

Bartter's syndrome is a rare renal disorder, and since there are few case reports of Bartter's syndrome complicating pregnancy are few, the changes of electrolytes and hormonal metabolism during pregnancy are unknown. We describe and discuss the course of pregnancy complicated with Bartter's syndrome.

Adult↗

Potential role of recombinant annexin II in diabetic vascular injury.

Hyperinsulinemia and hyperglycemia have been associated with vascular injury such as atherosclerosis in diabetes mellitus. Recently, annexin II, a member of annexin family proteins, has been found to work as co-receptor on endothelial cells for plasminogen and tissue plasminogen activator, facilitating plasmin generation on the surface of vascular endothelium. In this review, we overviewed the effect of glucose and insulin on plasmin generation in endothelial cells and its potential modulation by recombinant annexin II (rAN II) based on our data.

Annexin A2↗