PubMed Health⌕ Search

Biomedical subjects

S Yoshimura

Publications and source records attributed to S Yoshimura.

At least 37 records · Page 2Linked to original sources
PubMed1991

Immunological tolerance induced by liver grafting in the rat: splenic macrophages and T cells mediate distinct phases of immunosuppressive activity.

In the rat combination DA into PVG, liver grafts are not rejected but induce donor-specific transplantation tolerance. We have examined the immunosuppressive properties of spleen cells from PVG recipients of DA liver grafts at various times post-grafting. The results indicate the development of two phases of cell-mediated suppressor activity, which appear to be mediated by separate spleen cell populations. Mitomycin-C-treated spleen cells taken from animals between 5 and 28 days post-grafting were able to suppress rat mixed lymphocyte reactions (MLRs). These 'early' suppressor cells were glass adherent and absent from populations purified by passage through nylon wool or G10 Sephadex columns. Suppression of MLR by purified glass adherent cells was not specific for either stimulator or responder haplotypes and was blocked by indomethacin. Nylon wool purified T cells were not suppressive at this time. Spleen cell suppressor activity declined to background levels after 35 days post-grafting. However, spleen cells from long-term surviving liver graft recipients (20 weeks or more) were again able to suppress MLR; the 'late' suppressor cells were nylon wool non-adherent and suppression was specific for the donor (DA) MHC type. We conclude that liver grafting in this combination generates early and late phases of suppression among spleen cells, that the early phase is produced by macrophages and mediated by prostaglandins and that the late phase is dependent on allospecific suppressor T cells.

Animals↗
PubMed1991

Exact ultrastructural localization of glutathione peroxidase in normal rat hepatocytes: advantages of microwave fixation.

Glutathione peroxidase (GSH-PO), a highly soluble, selenium-dependent enzyme metabolizing lipid peroxides, is allegedly distributed in both the cytosol and mitochondria. With the pre-embedding method of immunoelectron microscopy for GSH-PO employing conventional immersion-fixation, the nuclei of rat hepatocytes stain positively, whereas mitochondria are negative. Such observations are inconsistent with the results of biochemical and immunoblot analyses using isolated subcellular fractions. In the present study, we employed the combination of microwave irradiation and fixation in 4% paraformaldehyde (PFA), with or without 0.1% glutaraldehyde (GA), to enhance the accuracy of ultrastructural localization of GSH-PO in rat liver. A small block of liver was irradiated by microwave for 10 sec in cold cacodylate-buffered 4% PFA containing 0.1% GA. After further immersion of the tissue in 4% PFA at 4 degrees C for 1-6 hr, the standard procedure for pre-embedding immunoelectron microscopy was employed. We observed partial inhibition of artifactual diffusion of cytosolic GSH-PO into the nuclei and consistent GSH-PO localization in mitochondria. Dual localization of this enzyme in the cytosol and mitochondria of normal rat hepatocytes was thus confirmed.

Animals↗
PubMed1991

[Multiple aspergillus brain abscess complicated with systemic lupus erythematosus--case report].

A 15-year-old female was hospitalized for the treatment of systemic lupus erythematosus complicated with nephritis. She improved with administration of steroid hormones and an immunosuppressant, plasma exchange, and dialysis. However, a lung abscess developed 6 months after admission, and multiple brain abscesses appeared 2 months after the onset of the lung abscess. The lung abscess faded with oral administration of fluocytosine and intravenous administration of miconazole, but the brain abscesses enlarged. Intrathecal administration of miconazole was not effective. Therefore, the abscess in the right frontal lobe was surgically removed and an Ommaya's reservoir was placed in the anterior horn of the right lateral ventricle. Aspergillus was identified in the removed abscess. Subsequently, miconazole was administered intraventricularly through the Ommaya's reservoir 10 mg daily for 1 month. The abscesses in the left parietal lobe gradually diminished. One year later, she complained of right hypesthesia again. Computed tomography scan revealed enlargement of the abscess. Miconazole was administered intravenously and intraventricularly for 1 month. Second craniotomy was performed 16 months after the first surgery and the abscess was completely removed. She was discharged with mild hypesthesia of the right leg. It is concluded that intraventricular administration of miconazole through an Ommaya's reservoir is an effective therapy for central nervous system aspergillosis.

Adolescent↗
PubMed1991

Expression of heat shock protein 70 and c-myc protein in human breast cancer: an immunohistochemical study.

The major heat shock protein, HSP70, protects cells from a variety of stressful stimuli, while c-myc protein allegedly stimulates the expression of HSP70 by transacting on the HSP70 promotor. The present study was aimed at correlating the expression of HSP70 with that of c-myc protein in benign and malignant breast lesions. Indirect immunoperoxidase and immunoblotting techniques using monoclonal antibodies were employed. Fresh frozen sections were prepared from five fibroadenomas and 59 breast carcinomas. Immunohistochemically, both substances were localized in the nuclei and/or cytoplasm of normal and neoplastic epithelial cells. The stromal cells were positive for c-myc protein but negative for HSP70. The expressions of HSP70 and c-myc protein were comparable to each other in the malignant cells from 37 (63%) carcinomas. In 17 (29%) carcinomas, c-myc protein expression predominated over that of HSP70, whereas in five (8%) carcinomas, HSP70 was predominant. Carcinomas with high-grade nuclear atypia often showed negative HSP70 staining, whereas tumors with nuclear HSP70 localization tended to accompany lower-grade nuclear atypia. A similar relation was also observed between c-myc protein expression and nuclear atypia of the tumor. All five fibroadenomas and most of the non-neoplastic epithelial cells adjacent to cancer showed strong reactivities with both substances. Immunoblot analysis for HSP70 revealed a clear, single band in the extract of tumors with strong HSP70 staining, but no, or only faint, bands were seen in the extract of immunohistochemically HSP70-negative carcinomas. The discrepancy between the expressions of each substance in a certain percentage of breast carcinomas may suggest the presence of HSP70 production mechanisms other than the c-myc protein-triggered promotor pathway.

Adenofibroma↗
PubMed1991

Structural analysis of the human HOX4A homeobox gene.

The HOX4A gene, one of a cluster of homeobox-containing genes on human chromosome 2, has been isolated by screening a genomic cosmid library with the HOX4B cDNA probe. The amino acid sequence was predicted according to the conceptual translation of 13 homology groups of human HOX genes (1). The HOX4A gene consists of at least two exons separated by a long intron of 1860 bp. The HOX4A protein predicted from the nucleotide sequence of the HOX4A gene is comprised of 416 amino acid residues. Comparison of the predicted HOX4A protein with the HOX2G protein revealed three regions of sequence similarity: an N-terminal octapeptide, a hexapeptide (pre-box) upstream of the homeodomain, and the homeodomain at the C-terminus.

Animals↗
PubMed1991

[Visual impairment complicated with meningioma].

Among 106 patients of meningioma surgically experienced the past 10 years between 1981 and 1990, twelve of meningioma with progressive visual impairment were analyzed in relation to postoperative visual outcome. There were four males and eight females, and the age ranged from 33 to 61 years with the average 48 years. The distribution of tumor location was 6 cases in tuberculum sellae, 3 cases in the inner side of sphenoid ridge, and 3 cases in olfactory groove. The size of tumor in each case was 2 to 7 cm in diameter, and in 8 cases more than 3 cm. The duration of visual disturbance was between 3 months and 10 years with the average 3 years. For all cases, surgical removal of the tumor was performed totally by pterional and bifrontal approach. Consequently, 58.3% of 7 cases had improved vision postoperatively, 16.7% of 2 cases remained unchanged, and 25.0% of 3 cases were worse, including one case of malignant meningioma, Visual outcome was mainly affected by a duration of symptoms, a tumor size, a preoperative visual impairment, and in special, a situation of optic nerve where compression of tumor itself and adherence to the surrounding tissues took place. On operation, great care should be paid for a case of long-standing, severe visual disturbance as demonstrating hemianopsia with visual narrowing less than 50 degree by perimetry, and also for preservation of the feeding arteries of optic nerves.

Adult↗
PubMed1991

Glutathione peroxidase and glutathione S-transferase, class alpha, in rat intestine. Immunohistochemical and immunoblotting studies on changes in expression of these antilipoperoxidative enzymes during normal development.

Glutathione peroxidase (GSH-PO) and glutathione S-transferase (GST), class alpha, showing GSH-PO-like enzymatic activity, were localized immunohistochemically in frozen sections of rat intestine in order to elucidate changes in the expression of these antilipoperoxidative enzymes during normal development. The direct immunoperoxidase method was performed using specific rabbit antibodies (Fab fragments) against the enzymes purified from rat liver. Immunoreactive GSH-PO and GST-alpha were demonstrated in the intestinal villous epithelial cells. In the duodenum, GSH-PO was positive during the period from 19 days of gestation to 1 week after birth, while GST-alpha was negative during this period. Two weeks after birth, positivity for GST-alpha appeared, and GSH-PO became undetectable. In the ileum, both of the enzymes were observed until 2 weeks of age, but after weaning their expression disappeared. These immunohistochemical findings were confirmed by immunoblot analysis using intestinal tissue extracts. To evaluate environmental effects on the expression of these enzymes, germ-free animals, common bile duct-ligated rats, and Hank's solution-fed infant rats were prepared. No remarkable alterations in the immunohistochemical localization pattern were observed. Since the switching of enzyme expression around the time of weaning was not influenced by these experimentally induced environmental conditions, it appears that these enzymatic changes are genetically predetermined.

Aging↗
PubMed1991

Molecular cloning of human plasma glutathione peroxidase gene and its expression in the kidney.

A genomic clone containing the human plasma glutathione peroxidase (GSH-Px) gene has been isolated using a rat plasma GSH-Px cDNA as a probe. The partial nucleotide sequence of the clone completely matched the sequence of the human plasma GSH-Px cDNA. The results of Southern blot hybridization indicate that the human plasma GSH-Px gene consists of at least 4 exons and 3 introns, and spans about 12 kb. RNA blot analysis demonstrated that the human plasma GSH-Px gene is expressed in the kidney.

Animals↗
PubMed1991

[Drug concentration in cancerous large bowel tissue and thymidylate synthase inhibition rate after administration of tegafur and UFT].

Tegafur and UFT are most widely used for the treatment of cancers of the gastrointestinal tract. FdUMP, a metabolite of 5-fluorouracil(5-FU), is known to have an inhibitory activity of thymidylate synthase (TS). We administered 600 mg/day of tegafur or UFT to 37 patients with cancer of the large bowel beginning 1 week prior to surgery and then measured the concentrations of tegafur and 5-FU, and TS inhibition rate in the excised tissue. Our results showed that the concentrations of 5-FU in tumor were 0.077 +/- 0.026 microgram/g in tegafur group and 0.208 +/- 0.143 microgram/g in UFT group, with the UFT showing significantly higher levels (p less than 0.05). On the other hand, TS inhibition rates in tumor tissue were 45.5 +/- 13.3% in tegafur group and 56.1 +/- 13.0% in UFT group, with a significantly higher level existing in the latter group (p less than 0.05). Furthermore, the same high 5-FU concentration and TS inhibition rates were observed in the lymph nodes affected by metastasis. No difference between the tegafur and UFT groups was noted in normal tissue or normal lymph nodes, and compared to tegafur, UFT showed an effective action on cancerous large bowel tissue.

Antineoplastic Agents↗
PubMed1990

Role of active oxygen species in diethyldithiocarbamate-induced gastric ulcer in the rat.

Diethyldithiocarbamate, an inhibitor of Cu,Zn-superoxide dismutase, was recently found to be ulcerogenic in the rat stomach, and active oxygen species were found to be responsible for its ulcerogenicity. To clarify which active oxygen species play a role in ulcerogenesis, the effects of various scavengers and iron-chelators were studied. As superoxide dismutase and catalase reduced the ulcerogenesis induced by diethyldithiocarbamate, the superoxide radical and hydrogen peroxide were considered to play a pathogenic role in this ulcer model.

Animals↗
PubMed1990

Mitogenic activity of soluble preparations from Plasmodium berghei-infected erythrocytes to L3T4+, Lyt2- and L3T4-, Lyt2+ T-cell subsets.

The mitogenic activity of soluble preparations of Plasmodium berghei-infected erythrocytes (PBEP) in cultures of T or non-T cells isolated from spleens of naive mice was investigated. The proportion of cells at each phase in the cell cycle was examined by flow cytometry after incubation with various concentrations of PBEP; the proliferation index (PI-cell numbers at S, G2 and M phases/cell numbers at all phases x 100) was calculated. An addition of PBEP led to significant increases in the PI levels of T cells, but not in those of non-T cells. Moreover, when PBEP were added to L3T4+, Lyt2- (helper) or L3T4-, Lyt2+ (suppressor) T-cell fractions separated from rosette-forming T cells in spleens, significant increases in PI levels were detectable in both helper and suppressor T-cell cultures. These results indicate that PBEP have a mitogenic activity directed to both helper and suppressor T-cell fractions isolated from spleens of naive mice and that PBEP or Plasmodium parasites may in this way induce complicated immune responses during malaria infection.

Animals↗
PubMed1990

An immunohistochemical study of copper, zinc-containing superoxide dismutase detected by a monoclonal antibody gastric mucosa and gastric cancer.

The immunohistochemical localization of copper, zinc-superoxide dismutase (Cu,Zn-SOD) in human gastric mucosa and gastric cancer was studied using a monoclonal antibody. In gastric mucosa, parietal cells, pyloric glandular cells and foci of intestinal metaplasia showed positive staining in the cytoplasm and/or nucleus. The wide distribution of Cu, Zn-SOD in the gastric mucosa suggests cell function may be vulnerable to active oxygen species. In gastric cancer, 34 of 70 cases showed a positive reaction for Cu, Zn-SOD. There was a relationship between the grade of Cu,Zn-SOD immunoreactivity and the histological type of gastric cancer, well-differentiated types of gastric cancer being more frequently positive. The positive cases of poorly-differentiated adenocarcinoma were characterized by a pattern of diffusely infiltrative invasion. These results suggest that some types of gastric cancer are resistant to active oxygen species.

Adenocarcinoma↗
PubMed1990

Immunohistochemical and immunoblotting detection of cytokeratin in smooth muscle tumors.

Forty-six smooth muscle tumors, including 35 of gastrointestinal origin, were studied immunohistochemically for the localization of cytokeratin using a variety of monoclonal antibodies. In formalin-fixed, paraffin-embedded material, six of 40 leiomyomas, two of five leiomyosarcomas and one leiomyoblastoma were immunoreactive for cytokeratin in a few tumor cells. A proportion of non-neoplastic smooth muscle cells also exhibited a positive reaction. In fresh frozen sections of one gastric leiomyosarcoma, a high percentage of tumor cells were reactive with nine of the eleven anti-cytokeratin monoclonal antibodies examined. Cytokeratin-positive cytoplasmic filaments were further demonstrated by immunoelectron microscopy. By immunoblot analysis, an extract of this immunohistochemically cytokeratin-positive leiomyosarcoma showed a distinct band at the same position as an extract of pancreas, whereas no bands were seen in an extract of a cytokeratin-negative esophageal leiomyosarcoma. These immunohistochemical and immunoblotting findings indicate that a certain subset of smooth muscle neoplasms express genuine cytokeratin filaments.

Humans↗
PubMed1990

The effect of the follicular fluid adenosine 3',5'-monophosphate degradation rate on successful fertilization and cleavage of human oocytes.

Follicular fluid (FF) and oocytes were obtained from 19 women for in vitro fertilization. Ovulation was induced with clomiphene citrate and human menopausal gonadotropin. Thirty-seven FF samples containing mature oocyte-corona-cumulus complexes were used to measure steroids, gonadotropins, and cAMP. The FF specimens were divided into three groups: follicles yielding ova that were fertilized and cleaved (group A), follicles containing fertilized ova without further cleavage (group B), and follicles containing nonfertilized oocytes (group C). The FF levels of progesterone, 17 beta-estradiol, LH/hCG, and FSH did not differ significantly among the groups. Mean FF cAMP concentrations declined from 17.5 +/- 2.5 pmol/mL 15 min after follicle aspiration to 3.6 +/- 0.9 pmol/mL after 3 h. The initial FF cAMP concentration did not differ significantly among three groups. However, the cAMP degradation rate in group A (119 +/- 13 X 10(-4) pmol/min) was significantly greater than that in group B (62 +/- 10 X 10(-4) pmol/min) or group C (75 +/- 8 X 10(-4) pmol/min). In conclusion, an increased intrafollicular cAMP degradation rate was associated with successful fertilization and cleavage of human oocytes in vitro. These data suggest that the degradation rate of FF cAMP may be a marker of optimal follicular development and oocyte maturation.

Adult↗
PubMed1990

Suppression of messenger ribonucleic acid for glutathione peroxidase in chemically induced rat hepatocellular carcinoma and its biological significance.

Deviations of the enzyme activity, immunoreactivity and messenger ribonucleic acid (mRNA) levels of glutathione peroxidase (GSH-PO) in 3'-methyl-4-dimethylaminoazobenzene- induced hepatocellular carcinoma of the rat were investigated. Enzyme activities of GSH-PO were significantly lower in hepatocellular carcinomas than those in the normal control rat liver. Immunohistochemically, GSH-PO was strongly localized in normal hepatocytes, but was only faintly stained in hepatocellular carcinoma cells. Heterogeneous staining patterns of GSH-PO were observed among individual cancer cells. In Northern blot analysis, GSH-PO mRNA in the cancer tissue was decreased to two thirds of the level in normal hepatocytes. It was suggested that suppressed expression of GSH-PO in carcinogen-induced hepatocellular carcinomas occurred at the level of mRNA transcription.

Animals↗
PubMed1990

Molecular cloning of cDNA coding for rat plasma glutathione peroxidase.

The plasma glutathione peroxidase (PGSH-PO), which is different from erythrocyte glutathione peroxidase (EGSH-PO) in immunochemical property and substrate specificity, was purified from male Wistar rat serum. The amino acid sequence of 5 independent peptides were determined and a cDNA clone for this enzyme was isolated from placental cDNA library. The nucleotide sequence of the cDNA revealed that, similar to EGSH-PO cDNA, the seleno-cysteine was genetically encoded by "TGA" codon. On comparing the nucleotide sequences of EGSH-PO and PGSH-PO, no significant homology was found in the vicinities of "TGA" codons of both enzymes.

Amino Acid Sequence↗
PubMed1990

[Oocyte fertilizability and hormonal environment of human preovulatory follicles in hyperstimulated cycles in an in vitro fertilization program: Are mature preovulatory follicles undergoing atresia?].

Steroid hormones in preovulatory follicular fluid, maturity of the oocyte-corona-cumulus complex (OCCC), and oocyte fertilizability were studied in 55 hyperstimulated cycles in 40 patients who were indicated for in vitro fertilization and embryo transfer due to tubal infertility. Aspirated follicles were categorized into four groups according to the degree of oocyte maturation and fertilizability, i.e. follicle (Fol)-1 (non-fertilized, intermediate maturation), Fol-2 (fertilized, intermediate maturation), Fol-3 (fertilized, full maturation), and Fol-4 (non-fertilized, full maturation). Estradiol (E2), progesterone (P), and delta 4- androstenedione (delta 4A) concentrations were highest in Fol-3, being lower in Fol-2 and Fol-1 sequentially. Fol-3 contained significantly more E2 and P than did Fol-1, showing that the degree of oocyte maturation and fertilizability correlate with concentrations of E2 and P in the follicles. A comparison of Fol-3 and Fol-4 revealed significantly higher concentrations of delta 4A in Fol-4, whereas differences in E2 and P concentrations were not significant although Fol-4 values were lower. This comparison indicated that Fol-4 were already undergoing atresia at the time of oocyte retrieval, containing morphologically mature OCCC which had lost fertilizability. This study shows that steroid hormones in the follicular fluid reflect oocyte viability and fertilizability, and suggests that preovulatory follicles with mature oocytes can also undergo atresia.

Chorionic Gonadotropin↗