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Y Kitamura

Publications and source records attributed to Y Kitamura.

At least 505 records · Page 28Linked to original sources
PubMed1992

Age-related changes in NMDA-induced [3H]acetylcholine release from brain slices of senescence-accelerated mouse.

From the brain slices of normal mice (ddY strain, subcloned from dd strain in National Institute of Health in Japan), N-methyl-D-aspartic acid (NMDA) at 0.01-1 mM evoked [3H]acetylcholine (ACh) release in a concentration dependent manner. [3H]ACh release evoked by 1 mM NMDA was significantly inhibited by 2-amino-5-phosphonovaleric acid (APV), phencyclidine (PCP) and 5-methyl-10,11-dihydroxy-5H-dibenzo[a,d]cyclohepten-5,10-imine maleate (MK-801). The effects of NMDA were not seen in the Ca2+ free medium and were inhibited by physiological concentration (0.83 mM) of Mg2+. NMDA seems to cause ACh release from nerve terminals through the receptor-ion channel mediated mechanism in the mouse brain. Based upon these results, we determined the activity of a high K(+)- or NMDA-evoked [3H]ACh release using prone/8 strain of senescence-accelerated mouse (SAM-P/8) (a murine model of accelerated aging and memory dysfunction) and SAM-resistance/1 strain (SAM-R/1) (normal aging mice as the control) and these release activities were compared between both strains and during aging. [3H]ACh release evoked by 30 mM KCl was significantly lower than that of age-matched SAM-R/1 at 9 and 12 months. NMDA evoked the [3H]ACh release at 2, 6, 10 and 14 months in R/1 mice. In SAM-P/8 mice the activity of NMDA-evoked release was seen at 2 months, but markedly decreased afterwards. Nonsignificant difference was observed on the uptake of [3H]choline and on the spontaneous release of [3H]ACh between SAM-P/8 and SAM-R/1 strains, and during aging.(ABSTRACT TRUNCATED AT 250 WORDS)

Acetylcholine↗
PubMed1992

Glutamate inhibits adenylate cyclase activity in dispersed rat hippocampal cells directly via an N-methyl-D-aspartate-like metabotropic receptor.

Three major subtypes of glutamate receptors that are coupled to cation channels--N-methyl-D-aspartate (NMDA), kainate, and alpha-amino-3-hydroxy-5-methylisoxazole-4-propionate (AMPA) receptors--are known as ionotropic receptors in the mammalian CNS. Recently, an additional subtype that is coupled to GTP binding proteins and stimulates (or inhibits) metabolism of phosphoinositides has been proposed as a metabotropic receptor. Incubation of dispersed hippocampal cells from adult rats with glutamate or NMDA decreased forskolin-stimulated cyclic AMP (cAMP) accumulation; half-maximal effects were obtained with 5.6 +/- 2.2 and 6.4 +/- 2.3 microM, respectively. Kainate and quisqualate were less potent. The effect of glutamate was antagonized by 2,3-diaminopropionate and 2-amino-5-phosphonovalerate, NMDA/glutamate receptor antagonists, but not by 0.5 microM Joro spider toxin, a specific blocker of the AMPA receptor. The inhibitory effect of glutamate on cAMP formation was not blocked by 2 microM tetrodotoxin or by the absence of Ca2+. In hippocampal membranes, glutamate, similar to carbachol, inhibited adenylate cyclase activity in a GTP-dependent manner. These findings suggest that the glutamate inhibition of adenylate cyclase is direct and is not due to a result of the release of other neurotransmitters. The effect of glutamate on cAMP accumulation was observed in an assay medium containing 0.7 mM MgCl2, which is known to inhibit both ionotropic NMDA receptor/channels in the hippocampus and metabotropic NMDA receptors in the cerebellum. The inhibitory effect of glutamate was abolished by pertussis toxin treatment.(ABSTRACT TRUNCATED AT 250 WORDS)

Adenylyl Cyclase Inhibitors↗
PubMed1992

The pH dependent uptake of enoxacin by rat intestinal brush-border membrane vesicles.

The mechanism of the intestinal transport of enoxacin, an orally active fluoroquinolone antibiotic, has been investigated using brush-border membrane vesicles isolated from rat small intestine. The initial rate and time-course of enoxacin uptake were considerably dependent upon the medium pH (pH 5.5 greater than pH 7.5) and upon the percent ionization of the carboxyl group (pKa 6.2, anionic charge), namely, the degree of uptake of cationic form was higher than that of the zwitterionic form. There was evidence of transport into the intravesicular space as shown by the effect of extravesicular medium osmolarity on enoxacin uptake at steady state (30 min). This transport across the brush-border membrane was stimulated by the valinomycin-induced K(+)-diffusion potential (interior negative) and an outward H(+)-diffusion potential. Furthermore, changing the pH of the medium from 5.5 to 7.5 significantly decreased the effect of valinomycin-induced K(+)-diffusion potential on the enoxacin uptake. These results suggest that the uptake behaviour of the cationic form of enoxacin plays an important role in the intestinal absorption process of enoxacin.

Animals↗
PubMed1992

Gynecomastia and ectopic human chorionic gonadotropin production by transitional cell carcinoma of the bladder.

We report a patient with gynecomastia and ectopic production of human chorionic gonadotropin (HCG) by a transitional cell carcinoma of the bladder. In the present case, serum HCG levels and gynecomastia paralleled the clinical course. On admission, the patient was suffering from invasive transitional cell carcinoma (grade 3) of the bladder with metastasis to the left inguinal lymph nodes, together with gynecomastia. The serum HCG level was also elevated. After anticancer chemotherapy, the apparent bladder lesion and gynecomastia disappeared, and the serum HCG level declined to within normal limits. About 2 months after discharge, when the patient suffered from recurrent invasive tumors of the bladder, gynecomastia reappeared and the serum HCG level again became elevated. beta-HCG was demonstrated in biopsy tissue using the immunoperoxidase technique. The presence of beta-HCG was always focally demonstrated and was shown to be localized in the cytoplasm of the tumor cells.

Carcinoma, Transitional Cell↗
PubMed1992

[Incidence of renal cell carcinoma in Chiba Prefecture, Japan; ten years experience].

Many reports about the increase of renal cell carcinoma patients have been published in Japan recently, however, the real fluctuations in the total number of patients in relation to the change of population have not been reported yet. Most of the patients with renal cell carcinoma in the last 10 years were examined in Chiba prefecture, which has a population of about five million and 25 active urological offices. Histologically confirmed cases were investigated by sending questionnaire letters. The items were as follows; sex, age, address, occupation, family history, past history, symptoms, examination methods that first detected the tumor, operation date, tumor diameter and clinical stage. Twenty two offices returned answers and 560 cases who lived in Chiba were found to have renal cell carcinoma from 1980 to 1989. Yearly incidence rates per 100,000 persons demonstrated a significant increase from 0.32 to 2.07. Small, asymptomatic and low stage cancers have been increasing rapidly, however, the rate of metastatic disease has not shown any decrease. The main cause of rapid increase seems to be attributed to progress in diagnostic methods and increase of early detection, but the possibility of an increase in some carcinogenic factors can not be ruled out.

Adult↗
PubMed1992

[Prognostic factors in patients with invasive differentiated thyroid carcinoma who underwent palliative resection].

In order to determine surgical strategy for locally advanced thyroid carcinoma, a multivariate analysis of prognostic factors was carried out with 70 patients of locally advanced thyroid carcinoma who underwent palliative surgery. Multivariate analysis was conducted by Cox's proportional hazard model. The patients have been followed up from 5 to 26 years. We have demonstrated the influence of age, sex, distant metastasis, pathological findings, numbers of adjacent organs, infiltrated, extent of resection, external irradiation and 131I therapy on survival. The result of this study showed that age had an impact on survival. The survival rate of the patients under 40 years was much better than that of the patients 40 years and over. The result implies that aggressive surgery and postoperative adjuvant therapy should be considered in the old patients, but not always be indication in the young patients.

Adenocarcinoma↗
PubMed1992

[An evaluation of perioperative and continuous infusion of tegafur as surgical adjuvant chemotherapy of resected gastric cancer].

Perioperative continuous intravenous infusion of Tegafur (FT) seems theoretically an effective adjuvant chemotherapy for patients with gastric carcinoma. Then we estimated the clinical effect of this therapy on the survival of patients who had undergone curative (Stage I, II, III) and non-curative (Stage IV) resection of a primary gastric carcinoma. One hundred fifty patients received chemotherapy and two hundred thirty-seven were observed. Results showed a significant difference in survival curves of Stage I (p less than 0.01) and Stage III (p less than 0.01). The 5-year survival rate was 100% for the adjuvant therapy arm and 82% for the observation arm in Stage I. In stage III, the survival curve of both arms was similar from the beginning to the 5th year, but the 7-year survival rate was 53% and 39%, respectively. There was no serious side effect of chemotherapy. These results demonstrate that this chemotherapy regimen is beneficial and recommendable as a perioperative adjuvant chemotherapy for resected gastric cancer in which the cancer cells were almost removed.

Chemotherapy, Adjuvant↗
PubMed1991

Anemia and mast cell depletion in mutant rats that are homozygous at "white spotting (Ws)" locus.

Mice possessing two mutant alleles at the W or Sl locus are anemic and deficient in mast cells. These mouse mutants have black eyes and white hair. Because homozygous mutant rats at the newly found white spotting (Ws) locus were also black-eyed whites, the numbers of erythrocytes and mast cells were examined. Suckling Ws/Ws rats showed a severe macrocytic anemia and were deficient in mast cells. When bone marrow cells of normal (+/+) control or Ws/Ws rats were injected into C3H/He mice that had received cyclophosphamide injection and whole-body irradiation, remarkable erythropoiesis occurred in the spleen of +/+ marrow recipients but not in the spleen of Ws/Ws marrow recipients. When skin pieces of Ws/Ws embryos were grafted under the kidney capsule of nude athymic rats, mast cells did develop in the grafted skin tissues. Therefore, the anemia and mast cell deficiency of Ws/Ws rats were attributed to a defect of precursors of erythrocytes and mast cells. Because the magnitude of the anemia decreased and that of the mast cell deficiency increased in adult Ws/Ws rats, this mutant is potentially useful for investigations about differentiation and function of mast cells.

Anemia↗
PubMed1991

6-Deoxy-D-talan and 6-deoxy-L-talan. Novel serotype-specific polysaccharide antigens from Actinobacillus actinomycetemcomitans.

Serotype-specific polysaccharide antigens from Actinobacillus actinomycetemcomitans ATCC 29523 (serotype a) and NCTC 9710 (serotype c) were extracted from whole cells by autoclaving and purified by ion-exchange chromatography and gel filtration. Analysis of component sugars by gas-liquid chromatography-mass spectrometry, high performance liquid chromatography, and NMR together with optical rotation data showed that the serotype a antigen was composed solely of 6-deoxy-D-talose, whereas the serotype c antigen consisted of 6-deoxy-L-talose. Structural analysis indicated that both of these antigens were composed of closely related repeating units, -3)-6-deoxy-alpha-D-Talp-(1-2)-6-deoxy-alpha-D-Talp-(1-(sero type a) and -3)-6-deoxy-alpha-L-Talp-(1-2)-6-deoxy-alpha-L-Talp-(1-(sero type c). 1H and 13C NMR analysis showed that both of these serotype antigens contained one acetyl group/2 sugar residues. These acetyl groups localized at the O-2 position of 3-linked 6-deoxy-D-talose (serotype a) or O-4 position of 3-linked 6-deoxy-L-talose residues (serotype c), respectively. These results coupled with our previous findings on the serotype b antigen (Amano, K., Nishihara, T., Shibuya, N., Noguchi, T., and Koga, T. (1989) Infect. Immun. 57, 2942-2946) showed that the serotype antigens from A. actinomycetemcomitans are a group of novel polysaccharides with structural features closely related biosynthetically.

Actinobacillus↗
PubMed1991

Illegitimate recombination in a bovine papillomavirus shuttle vector: a high level of site specificity.

Recombination in a bovine papillomavirus shuttle vector carrying direct repeats of Moloney murine leukemia virus LTR sequence was examined. Differently from similar vectors carrying direct repeats of SV40 polyA addition signal or neomycin resistance gene, the vector exhibited no homologous recombination between the repeats. Instead, illegitimate recombination took place. There were two major types of recombination products from the restriction cleavage pattern. The plasmids in independent cellular clones belonging to the same recombination type shared the identical crossover point. Thus, in this plasmid, illegitimate recombination occurred at preferential sites involving exactly the same sequences.

Animals↗
PubMed1991

In vitro "progression" of bovine papillomavirus-transformed cells: loss of contact sensitivity after multiple rounds of selection.

The transformed phenotype of C127 cells harboring bovine papillomavirus shuttle vector pdBPVMMT neo(342-12) was suppressed by direct contact with untransformed C127 cells. By repeated selections of rare foci developing on untransformed cell monolayers, we obtained a cellular clone of BPV transformants which formed foci on the untransformed C127 cells as efficiently as on plastic surface. The BPV genome in the mutant cells showed extensive genetic rearrangements, duplication of upstream regulatory region and deletion of pBR322-derived sequence and its flanking. There was an increase in BPV-transformant in contact with the untransformed C127 cells resulted in a marked reduction of the BPV transcripts, while in the case of the mutant transformant the reduction was much slighter. This indicates that the transcription level of the BPV genome was controlled by a cell-cell contact signal.

Animals↗
PubMed1991

Nerve growth factor induces development of connective tissue-type mast cells in vitro from murine bone marrow cells.

The effect of nerve growth factor (NGF) on proliferation/differentiation of mast cells was investigated in vitro. Although NGF alone neither supported colony formation of bone marrow-derived cultured mast cells (BMCMC) nor induced development of mast cell colonies from nonadherent bone marrow cells (NBMC), addition of NGF to the suboptimal dose of interleukin 3 (IL-3) significantly increased the numbers of mast cell colonies produced by BMCMC or NBMC in methylcellulose. When stimulated by IL-3 alone, cells in mast cell colonies were not stained by berberine sulfate, a fluorescent dye. In contrast, mast cells developing in methylcellulose cultures obtaining both IL-3 and NGF were stained by berberine sulfate. The fluorescence was abolished by the treatment of heparinase but not of chondroitinase ABC, suggesting that mast cells stimulated by IL-3 and NGF produced and stored heparin proteoglycan. The histamine content of BMCMC maintained by IL-3 was also increased by addition of NGF. Since BMCMC showed mucosal mast cell-like phenotype, NGF appeared to induce the phenotypic change to connective tissue-type mast cells (CTMC). In the culture containing BMCMC, 3T3 fibroblasts, and IL-3, the phenotypic change of BMCMC to CTMC was observed as well. Since NGF was detected in this coculture and since addition of anti-NGF monoclonal antibody suppressed the phenotypic change, NGF produced by fibroblasts appeared to induce the phenotypic change. Neither BMCMC alone nor IL-3 alone increased the concentration of NGF. Therefore, there is a possibility that BMCMC stimulated by IL-3 may induce the production and/or release of NGF by fibroblasts.

Animals↗
PubMed1991

Homologous recombination in bovine papillomavirus shuttlevecter; effect of relative orientation of substrate sequences.

Relative orientation of recombination substrates, neo gene, strongly influenced homologous recombination events in a bovine papillomavirus shuttle vector. Between direct repeats, recombination occurred at a high frequency while between inverted repeats, it was rare. Double strand break near the mutation site increased the recombination frequency between inverted repeats but not between direct repeats. Formation of long heteroduplex as a recombination intermediate may explain this apparently paradoxical phenomenon.

Base Sequence↗
PubMed1991

Anaesthetic management of phaeochromocytoma associated with tricuspid atresia.

The anaesthetic management of a patient with phaeochromocytoma, tricuspid atresia and pulmonary vascular stenosis is reported. The patient received no preoperative preparation with adrenergic blockers. Anaesthesia was induced and maintained with fentanyl, diazepam and sevoflurane. Intraoperative blood pressure was controlled with sodium nitroprusside, sevoflurane, phentolamine, and propranolol. For hypotension after resection of the tumour norepinephrine was required. This patient did not have a systemic to pulmonary shunt procedure performed, so the maintenance of pulmonary blood flow in the presence of haemodynamic instability during operation for phaeochromocytoma was a major concern. Monitoring of oxyhaemoglobin saturation (SpO2) with a pulse oximeter was considered to be useful because SpO2 may reflect pulmonary flow. During serious haemodynamic disturbances due to the manipulation of the tumour, the heart rate was inversely correlated with SpO2, but the relationship between mean arterial pressure and SpO2 was weak. Therefore, control of heart rate appeared to be more important than control of blood pressure in this case.

Adolescent↗
PubMed1991

Effect of dexamethasone on uterine cell death.

Oestrogen, progesterone and androgen inhibit uterine cell death after the depletion of oestrogen. In the present study, we investigated effects of glucocorticoid on death of mouse uterine cells. Castrated female mice were given a daily injection of 17 beta-oestradiol (0.2 microgram/mouse/day) for 3 days, and then an injection of 5'-[125I]iodo-2'-deoxyuridine ([125I]IdUrd) to label DNAs of uterine cells with 125I. Mice were killed at intervals during subsequent treatments, and the retention of [125I]IdUrd incorporated into the whole uterus was determined. On subsequent injection of vehicle only, the 125I-radioactivity retained in the whole uterus rapidly decreased. Injections of dexamethasone (50 micrograms/mouse/day) reduced the loss of 125I-radioactivity slightly but significantly. Dexamethasone also showed synergistic effects on the retention of 125I-radioactivity when it was daily injected together with 17 beta-oestradiol, progesterone or 5 alpha-dihydrotestosterone. The present results suggest that glucocorticoid may affect the processes involved in the uterine cell death, in a manner such as inhibiting the uterine cell death or delaying the removal of DNAs of dead cells from the uterus.

Animals↗
PubMed1991

Fibroblast-dependent differentiation/proliferation of mast cells.

Fibroblast-dependent differentiation and proliferation of mast cells were reviewed from the viewpoint of mast cell-deficient mutant animals. Mice of W/Wv, Sl/Sld or mi/mi genotype are deficient in mast cells. However, since T cell-dependent differentiation and proliferation of mast cells are intact in these mutant mice, mast cells do develop when bone marrow cells of these mutant mice were cultured in the presence of T cell-derived growth factors. Cultured mast cells (CMC) of W/Wv mice cannot receive the proliferative stimulus from fibroblasts whereas fibroblasts derived from Sl/Sld embryos cannot provide normal (+/+) CMC with the proliferative stimulus. The W locus encodes a tyrosine kinase receptor and the Sl locus the ligand for the receptor. Although +/+ CMC acquire the phenotype resembling connective tissue-type mast cells when cocultured with fibroblasts in medium containing T cell-derived growth factors, mi/mi CMC do not. We recently found a mast cell-deficient mutant of rats. Biological features of the mast cell-deficient rats were very similar to those of W/Wv mice. The mast cell-deficient mutant animals are invaluable tools for investigations of differentiation/proliferation and functions of mast cells.

Animals↗