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Biomedical subjects

K Yanagihara

Publications and source records attributed to K Yanagihara.

195 records · Page 11Linked to original sources
PubMed1977

Inward current of the rabbit sinoatrial node cell.

Inward currents of the rabbit sinoatrial node cell were examined in voltage-clamp experiments using the two-microelectrode technique. A fast and slow inward current could be separated from each other. The slow inward current was blocked by Mn and D 600, but it was insensitive to TTX. On the contrary, the fast inward current was blocked by TTX, but not by Mn and D 600. Both the fast and slow inward currents disappeared on Na removal. The fast inward current system was fully inactivated by holding the membrane potential positive to -40 to -50 mV, while the slow inward current system was recorded with the holding potential up to -20 mV. The voltage dependence of the inactivation of the 2 inward current systems and their dependence on [Na]0 suggests that the rising phase of the spontaneous action potential in the S-A node cell is produced mainly by Na current through the slow inward current system.

Animals↗
PubMed1977

Infectious murine type-C viruses released from human cancer cells transplated into nude mice.

Type-C virus particles were revealed by electron microscope in 6 of 9 tumours of cultured and biopsied human cancers heterotransplanted into nude mice. Some tumours in nude mice were explanted for in vitro cultivation. The virus particles were also found in the cultures derived from the virus-positive tumors. They were mostly found extracellularly, but the particles in budding process were also encountered frequently. Cytological study and karyotype analysis of the cultured cells proved these virus-releasing cells as of hus of human origin. From the close correlation between the statistical virus counts and the complement fixation titers for murine gs antigen of the tumors and their cultures, these viruses propagated in human cancer cells were confirmed to be infectious viruses of nude mouse origin. The virus replicating in human cancer cells was readily infected in some of innocent human cancer cells by co-cultivation. It is to be emphasized that infection of animal endogenous viruses on heterotransplanted human cancer cells is a bothersome contamination for human cancer research, especially when searching for a human tumor virus candidate.

Animals↗
PubMedDate not supplied

Weak association between retinopathy of prematurity and neurological disorders in childhood.

An attempt was made to elucidate the association between retinopathy of prematurity (ROP) and neurological disorders in infants of very low birth weight. In this retrospective study, 1081 Japanese children weighing less than 1500 g at birth were classified into four subgroups according to birth weight. In each subgroup, the association among cerebral palsy (CP) or mental retardation (MR) and ROP, treated ROP, and cicatricial ROP was analyzed statistically. In the population as a whole, CP and MR were positively associated with ROP. However, in the birth weight subgroup analysis, no significant association was found. We can conclude that there is a weak association between ROP and CP or MR.

Cerebral Palsy↗
PubMedDate not supplied

Mutational analysis of the beta-catenin gene in gastric carcinomas.

Previous studies reported that mutation of the adenomatous polyposis coli (APC) gene was not observed in the majority of gastric cancers. To evaluate the role of the APC/beta-catenin/Tcf pathway, we analyzed mutations in the beta-catenin gene and the accumulation of beta-catenin protein in gastric carcinomas. An interstitial deletion spanning exon 3 of the beta-catenin gene was observed in 1 of 13 gastric cancer cell lines. No missense mutation was found in these 13 cell lines. Nuclear and/or cytoplasmic localization of beta-catenin was observed in 16 of 70 primary gastric carcinomas by immunohistochemistry, while we found no mutations in exon 3 in 35 carcinoma tissues available for PCR amplification. Our findings suggest that somatic mutations of the beta-catenin gene are rare in human gastric carcinomas and that accumulation of normal beta-catenin protein in a subset of gastric cancers may be due to other mechanisms of its activation.

Adenomatous Polyposis Coli Protein↗
PubMedDate not supplied

Combination therapy with fluconazole and flucytosine for pulmonary cryptococcosis.

We investigated, in vitro, the combined effects of fluconazole (FLCZ) and flucytosine (5-FC) against different strains of Cryptococcus neoformans, and retrospectively analyzed the clinical efficacy of combination therapy of FLCZ and 5-FC in patients with pulmonary cryptococcosis. The minimum inhibitory concentrations (MICs) of antifungal agents and drug interaction were determined by the broth microdilution method and checkerboard titration. FLCZ and 5-FC showed synergistic activity against 8 (32%) of 25 strains of C. neoformans. The clinical efficacy of the 2 drugs when combined together was good in 9 (90%) patients and fair in 1 (10%) patient with pulmonary cryptococcosis. Renal dysfunction occurred in 1 patient. Our results suggest that a combination therapy using FLCZ and 5-FC is clinically useful in patients with pulmonary cryptococcosis who otherwise show a limited response to monotherapy.

Adult↗
PubMedDate not supplied

Comparison of the microbicidal activities of superoxidized and ozonated water in the disinfection of endoscopes.

The microbicidal activities of superoxidized water (electrolysed strong acid water [ESAW] or electrolysed weak acid water [EWAW]), ozonated water, 0.05% chlorhexidine and 2% glutaraldehyde were tested against seven strains of clinical micro-organism isolates. Following incubation of bacterial suspensions in ESAW and EWAW for 10 s, the number of micro-organisms was reduced below the detection limit. The microbicidal activities of ESAW and EWAW were similar to that of glutaraldehyde, and superior to ozonated water and 0.05% chlorhexidine. The microbicidal activities of ESAW, EWAW and ozonated water were markedly diminished in the presence of albumin. Microbial contamination of upper gastrointestinal endoscopes was detected after 90 endoscopic procedures, but treatment of the endoscope with ESAW, EWAW or ozonated water eradicated the microbes. These results indicate that ESAW and EWAW are effective disinfectants after mechanical cleaning of upper gastrointestinal endoscopes, and can, therefore, be used in the endoscopy unit.

Acids↗
PubMedDate not supplied

Antitumor potential of interferon-gamma: retroviral expression of mouse interferon-gamma cDNA in two kinds of highly metastatic mouse tumor lines reduces their tumorigenicity.

The antitumor effects of interferon (IFN)-gamma were examined in two types of malignant metastatic mouse tumor cell lines following their transfection with the IFN-gamma gene by retroviral gene transfer. In both ovarian and lung tumor lines, but more markedly in the latter, subcutaneous (s.c.) tumor progression of the IFN-gamma-producing cells was profoundly suppressed in the normal syngeneic as well as in athymic nude mice. In addition, experimental metastasis via the tail vein of the IFN-gamma producers was also suppressed. Lung tumor suppression was abolished by X-irradiation of the syngeneic mice or by the administration of antiasialoganglioside GM1 antibodies into the nude mice. These results suggest that tumor suppression is due to the effect of the tumor-derived IFN-gamma on the host antitumor mechanisms including natural killer cells. Moreover, tumorigenicity of several unrelated tumor cells was significantly reduced when s.c. injected as a mixture with the apparently benign IFN-gamma-producing lung tumor cells, so that such 'non-malignant' IFN-gamma-producing cells may have therapeutic benefit against certain other malignant tumors.

Animals↗