Search PubMed⌕ Search

Biomedical subjects

T Kohsaka

Publications and source records attributed to T Kohsaka.

At least 55 records · Page 3Linked to original sources
PubMed1997

Clinical role for a superantigen in Yersinia pseudotuberculosis infection.

Yersinia pseudotuberculosis is an enteric pathogen that causes a variety of clinical symptoms in the human. Recently, we reported the production of a superantigen (Y. pseudotuberculosis-derived mitogen, YPM) by this organism and characterized the gene structure of ypm. To further study the potential pathogenic role of YPM in Y. pseudotuberculosis infection, we assayed IgG anti-YPM antibodies and T cell antigen receptor-Vbeta expression of the T cells in peripheral blood and in mesenteric lymph node in patients acutely infected with Y. pseudotuberculosis. 20 out of 33 patients (61%) had an elevated antibody titer compared with healthy controls (P = 0.0001). Patients with systemic symptoms such as lymphadenopathy, transient renal dysfunction, and arthritis had significantly higher titers of anti-YPM than patients with gastrointestinal tract symptoms alone. T cells bearing the Vbeta3 gene segment were significantly increased (P = 0.009) among acute phase patients compared with healthy children. During the convalescence phase of the illness, there was a reduction in the abnormal level of Vbeta3 T cells. Moreover, in the mesenteric lymph node, an elevated level of Vbeta3 T cells compared with peripheral blood and a sequence diversity in the junctional region of the T cell antigen receptor beta-chain containing Vbeta3 element was observed in one patient. Together, these findings suggest that YPM was produced in vivo and played an important role in the pathogenesis of Y. pseudotuberculosis infection.

Adolescent↗
PubMed1997

In staphylococcus enterotoxin B (SEB)-stimulated human PBMC, the LAK activity of non-T cells might have a major role in the mechanism of glomerular endothelial cells' injury.

In this study the SEB-activated LAK cytotoxicity was identified and characterized in human peripheral blood lymphocytes (PBMC). After 3 days of SEB stimulation, the PBMC acquired a cytotoxicity against traditional LAK targets, K-562 and Daudi, beside that human glomerular endothelial cells (HGEC) were effectively lysed. The magnetic separation of SEB-stimulated CD5+ T cells revealed that the dominant LAK cytotoxicity remained in the CD5- lymphocyte fraction. The major part of the SEB-generated cytotoxicity of CD5- cells could be blocked with specific antibodies to IL-2 and IFN-gamma. The IFN-gamma pretreatment of HGEC reduced the target sensitivity, but because of the upregulation of MHC class II on HGEC surface, these cells were able to present SEB to CD5+ cells. These results suggested that in bacterial superantigen-mediated infection, the non-T (NK cells-derived) LAK cells might have a primary pathogenic role, and the adverse effect of IFN-gamma, that was massively secreted from superantigen-stimulated cells, requires greater consideration.

Antibodies↗
PubMed1997

Influence of ETR-p1/f1 antisense peptide on endothelin-induced constriction in rat renal arcuate arteries.

1. This study set out to examine the endothelin receptor subtypes mediating vasoconstriction in the rat renal arcuate artery. This was done in isolated vessels 120-200 microns in diameter, incubated with a selective agonist and the novel 'antisense' peptide to part of the human endothelinA receptor. 2. Groups of vessels (n = 6) were incubated with increasing concentrations of endothelin-1 (ET-1), from 1 to 100 nM, which caused a 65% maximal contraction at the highest dose with an pEC50 of 8.16 +/- 0.11 M. By contrast, in six other vessels sarafotoxin 6c over the same dose range gave a minimal contraction (around 5% of maximum). 3. Preincubation of six vessels with the antisense peptide ETR p1/f1 at 1 microM had no effect on the ET-1 induced vasoconstriction, in terms of displacement of the concentration-response curve or the maximal tension achieved by the agonist. In the six vessels exposed to 4 microM ETR p1/f1, there was a significant shift of the concentration-response curve and a lower pEC50 at 7.78 +/- 0.09 M (P < 0.05). At the highest concentrations of ETR p1/f1, there was a marked suppression of all responses to ET-1, which at the maximal concentrations tested, 0.1 microM, only reached some 10% of the maximal achievable contraction. 4. Increasing ET-1 concentrations up to 2 microM in vessels incubated with 40 microM ETR-p1/f1 showed that the blockade could be overcome and that the relationship was shifted to the right (P < 0.001) by approximately one log unit with a pEC50 of 7.13 +/- 0.11 M. A Schild plot of the data indicated the antagonist to be acting competitively at a single population of receptors. 5. At the highest concentrations tested, 40 microM, ETR-p1/f1 had no effect on noradrenaline-induced contractions, indicating a lack of non-specific actions. 6. Together, these data suggest that at the rat renal arcuate artery the endothelinA receptor is the predominant functional receptor mediating contraction. Furthermore, this study has shown the potential usefulness of this novel type of 'antisense' peptide in blocking receptor activation.

Amino Acid Sequence↗
PubMed1997

Linkage analysis and identification of deletion in Alagille syndrome gene.

Alagille syndrome (AGS) is a genetic disease and the responsible gene has already been mapped at 20p12. To more accurately detect the region of the AGS gene on the linkage map of chromosome 20p, 14 yeast artificial chromosome (YAC) clones were screened to construct a YAC contig in the candidate region and 13 locus markers and 2 sequence-tagged sites (STS) were ordered. Combining all of the analyses, a 1.3 Mb critical region from D20S507 to D20S61 for the AGS gene was identified. As the human Jagged 1 gene (JAG1) lies just in this region and is responsible for the AGS disease, the genomic DNA in an AGS family without a visible deletion were analyzed by single-strand conformational polymorphism (SSCP) and direct DNA sequencing, and a 2-bp (CT) deletion mutation at exon 26 of the JAG1 was identified.

Alagille Syndrome↗
PubMed1997

Intraalveolar expression of tumor necrosis factor-alpha gene during conventional and high-frequency ventilation.

The effects of conventional mechanical ventilation (CMV) and high-frequency oscillatory ventilation (HFO) on intraalveolar expression of the tumor necrosis factor-alpha (TNF-alpha) gene were studied in surfactant-depleted rabbits. After lung lavage with saline, 13 rabbits were administered either CMV (n = 6) or HFO (n = 7) for 1 h at an FiO2 of 1.0 and a mean airway pressure of 13 cm H2O. Lung lavage was then repeated. The rabbits' RNA was extracted from the lavage cells, and mRNA for TNF-alpha was quantitated by reverse-transcription polymerase chain reaction using glyceraldehyde 3-phosphate dehydrogenase (GAPDH) as an internal standard. At 1 h of ventilation, PaO2 was slightly lower with CMV than HFO, while lavage cell counts and cytology were similar between the two groups. The ratio of TNF-alpha mRNA to GAPDH mRNA increased with CMV (control, 0.48 +/- 0.04 [SE] versus 1 h, 1.02 +/- 0.14, p < 0.01) but did not change with HFO (0.55 +/- 0.07 versus 0.73 +/- 0.09). In a separate series of experiments, ten surfactant-depleted rabbits continued to be ventilated for 4 h either by CMV (n = 5) or HFO (n = 5). Conventional mechanical ventilation resulted in a progressive hypoxemia, decreased lung compliance, increased number of neutrophils in lung lavage fluid, and substantial morphological changes including hyaline membrane formation and neutrophil accumulation, whereas HFO was associated with minimal changes in such physiological and pathological abnormalities. These results suggest that activation of alveolar macrophages and production of proinflammatory cytokines may play a pivotal role in the early stage of ventilator-induced lung injury, and that ventilator mode (CMV or HFO) substantially modulates macrophage activation and hence the degree of lung injury.

Animals↗
PubMed1997

[The old and new problems of the antibiotics treatment in hemorrhagic enterocolitis and hemolytic uremic syndrome, according to Japanese epidemiological studies].

The treatment for hemorrhagic enterocolitis due to O157 E. coli infection has been discussed to prevent its aggravation to HUS, especially in terms of the effect of antibiotics. In June, 1996, massive outbreak of the infection occurred in Sakai city, Osaka, Japan. For the purpose of the prevention against secondary infection, antibiotics therapy was employed routinely in Sakai. The epidemiological results were as follows. A total of 25996 school children probably faced infection. Among them 4671 (admission 995) children became symptomatic and 102 developed HUS, leading the ratio of HUS versus symptomatic children to 2.18% which is significantly less than the average occurrence ratio of 4.0% at the same age group nationwide. We studied the possibility of lowering the incidence of HUS by the early diagnosis and the use of antibiotics. According to our survey(86-95), we examined 193 diarrhea associated HUS cases on the effect of antibiotics. There is no meaningful change despite treatment of antibiotics during enterocolitis stage in reducing the complication of HUS, but antibiotics therapy after the onset of HUS brought the prolongation of disease course. These two results were controversial, but the main factor might be the age difference between the two study groups. As previously reported, we could'nt propose the administration of antibiotics to the infants with hemorrhagic enterocolitis due to E. coli O157.

Adolescent↗
PubMed1996

Dual recognition of a human cytotoxic T-cell clone for melanoma antigens.

It is well known that tumor-specific CTLs have a crucial role in the elimination of tumors and that different CTL populations recognize tumor antigens in MHC-restricted and MHC-unrestricted manners. We have established two alpha beta CTL clones that recognize melanoma antigens in both human lymphocyte antigen (HLA)-A2-restricted and HLA-unrestricted manners. Flow cytometry analysis showed that these CTL clones carry CD3, CD8, and alpha beta T-cell receptor (TCR) and express low levels of CD56. In contrast, these CTL clones do not express CD16, indicating that they do not contain natural killer cells. TCR analysis of these CTL clones using an anchored PCR method revealed that each clone carries a single alpha beta TCR. Both CTL clones contained the same Valpha and Vbeta gene segments although they carried different Jalpha and Jbeta gene segments. Taken together, these results confirm that CTL clones that carry a single alpha beta TCR recognize melanoma antigens in both HLA-A2-restricted and HLA-unrestricted manners. It is strongly suggested that the dual recognition of these CTL clones for the melanoma antigens is mediated by TCRs. The novel mechanism for antitumor immunity by these CTLs may be important in the effective elimination of tumors in vivo.

Amino Acid Sequence↗
PubMed1996

Periapical lesions in rats with streptozotocin-induced diabetes.

The purpose of this study was to investigate histologically and histometrically the changes in pulpal periapical tissues after pulpal exposure in streptozotocin-induce diabetic rats. Control rats were injected with citrate buffer. Experimental rats were injected with streptozotocin dissolved in citrate buffer. All animals received a pulpal exposure in the left mandibular first molar. Blood glucose concentration was measured at, 0, 7, 14, 28, and 42 days. All animals were killed at 7, 14, 28, and 42 days after pulpal exposure, and their mandibles were evaluated histologically and histometrically. Blood glucose levels in the experimental rats were significantly higher than those in the control rats. In experimental rats, inflammation in the apical periodontal ligament and root resorption and alveolar bone resorption were more severe than that in control rats. This study also revealed histometrically that, in experimental rats, lesions in the periapical area were significantly larger than those in control rats.

Alveolar Bone Loss↗
PubMed1996

Primary cytotoxicity of SEB-activated human PBMC and separated CD8+ and CD4+ T lymphocytes elicited by two different stimulation protocols.

The primary cytotoxicity of Staphylococcal enterotoxin B (SEB)-stimulated PBMC and separated CD8+ and CD4+ T cells against Burkitt's lymphoma target cells has been characterized by applying two stimulation protocols. In the bulk protocol, the PBMC were stimulated with 100 ng/mL SEB for 3 days before separation to CD4+ and CD8+ T subsets. In the direct protocol, the separated CD4+ and CD8+ T cells were stimulated with 100 ng SEB preabsorbed to mitomycin C (MMC)-treated APC. Comparison of the results of the two different protocols revealed the following differences: (i) PBMC in the direct protocol provided greater cytolytic activity than in the bulk protocol; and (ii) the CD4+ T cells acquired cytotoxicity only in the direct protocol. Unexpectedly, the superantigen-dependent cellular cytotoxicity (SDCC) of SEB-stimulated cells was not dominant compared with the basal cytotoxicity. The classical NK target, K-562 was also sensitive to SEB-augmented cytotoxicity. The parallel stimulation with IL-2 and SEB caused a similar extent of cytotoxicity enhancement against both types of target cells. However, the cyclosporin A (CSA) inhibited only the SEB-induced cytotoxicity. The results suggest that SEB-induced PBMC acquire mainly a LAK-like cytotoxicity, as a consequence of newly produced lymphokines. This observation might propose a different approach in pathological studies.

Antigen-Presenting Cells↗
PubMed1996

High concentrations of immunoreactive inhibin in the plasma of mares and fetal gonads during the second half of pregnancy.

Plasma concentrations of immunoreactive (ir)-inhibin were measured in seven pregnant mares from around Day 140 of gestation to Day 2 after parturition using a heterologous bovine-based radioimmunoassay (RIA). Concentrations of luteinizing hormone (LH), follicle-stimulating hormone (FSH), oestradiol-17 beta, progesterone and relaxin were also measured in the same samples. A marked increase in plasma concentrations of ir-inhibin, FSH and LH occurred between Day 220 and Day 300 of gestation but the concentrations of all three hormones returned to baseline by about Day 320 (three weeks before parturition). In contrast, circulating concentrations of the three placental hormones, oestradiol-17 beta, progesterone and relaxin, increased during the final weeks of pregnancy and then decreased markedly to basal values within two days of parturition. There was a positive correlation between circulating concentrations of ir-inhibin and FSH (r = 0.75, P < 0.01) rather than the expected negative correlation. ir-inhibin was not detected in homogenates obtained at Day 190 of pregnancy and form term placenta, but high concentrations of ir-inhibin were present in homogenates of fetal and newborn gonads. Despite the high concentrations of ir-inhibin in these homogenates, they failed to exert any suppressive bioactivity on FSH secretion by rat pituitary cells cultured in vitro. Furthermore, immunohistochemical staining revealed the presence of inhibin in the interstitial cells of equine fetal gonads at Day 190 of gestation. These findings demonstrate for the first time that high concentrations of ir-inhibin, LH and FSH are secreted into the peripheral circulation of the mare during the second half of pregnancy. However, ir-inhibin present in the plasma of pregnant mares appears to be biologically inactive. This hormone is not presumed to be of placental origin but it is proposed that either the enlarged fetal gonads or the maternal ovaries, or both of these organs, may be a source of inhibin in response to the coincident increase in circulating concentrations of LH and FSH.

Animals↗
PubMed1996

Neuro-regulation of interleukin-6 gene expression in the spontaneously hypertensive rat kidney.

OBJECTIVE: To assess the influence of elevated renal sympathetic nerve activity on renal interleukin-6 (IL-6) and interleukin-1 alpha (IL-1 alpha) production and to compare the specificity of the constitutive production of these cytokines in the spleen and kidney of the spontaneously hypertensive rat (SHR). DESIGN: In acute studies, using anaesthetized and surgically stressed rats, the renal nerves either were not stimulated or were stimulated electrically to reduce renal blood flow by 15 or 30% for 1 h. The kidneys were then extracted for analysis. For the chronic study, Wistar rats and SHR aged 9 weeks were briefly anaesthetized and kidneys and spleen extracted for cytokine measurement. METHODS: Tissue samples were subjected to reverse transcriptase and polymerase chain reaction amplification to assess levels of IL-6 and IL-1 alpha. RESULTS: Renal nerve stimulation decreased levels of IL-6 messenger RNA in the SHR kidney, from a control value of 0.677 +/- 0.043 units to 0.624 +/- 0.049 and 0.383 +/- 0.078 units during the 15 and 30% reductions in renal blood flow induced neurally. The chronic experiments showed that, although there was no difference in constitutive production of IL-1 alpha between the kidney and spleen of Wistar rats and SHR, spleen levels of IL-6 were higher in the SHR and IL-6 was expressed constitutively neither in the Wistar rat nor in the SHR kidney. CONCLUSION: These data demonstrate that renal IL-6 gene expression is low in the SHR kidney under conditions of anaesthesia and surgical stress and that it is further decreased when the kidney is subjected to adrenergic influences. These studies help to define the deficiencies and abnormalities of the SHR Immune system.

Animals↗
PubMed1996

Regulation of the C3 production by gamma interferon from peripheral blood T cells in patients with membranoproliferative glomerulonephritis and poststreptococcal acute glomerulonephritis.

This study assessed the regulatory role of peripheral blood T cells in the C3 production in patients with poststreptococcal glomerulonephritis and branoproliferative glomerulonephritis. Peripheral blood T cells from patients at various stages of disease were cultured and the supernatants tested for gamma interferon (IFN-gamma) content and the capacity to stimulate C3 production by HuH-7 cells. Supernatants from patients with membranoproliferative glomerulonephritis and from convalescent patients with poststreptococcal glomerulonephritis significantly stimulated the C3 production; the degree of stimulation correlated with the IFN-gamma content of the supernatants. Similar results were obtained using recombinant IFN-gamma. In both cases, the effect was blocked by the addition of anti-IFN-gamma monoclonal antibody to the cultures. Interleukin 2 and interleukin 6 levels in supernatants from T cell cultures of patients and controls were essentially the same. In summary, IFN-gamma plays a regulatory role in C3 production by human hepatoma cell lines.

Acute Disease↗
PubMed1996

Complement 4 locus II gene deletion and DQA1*0301 gene: genetic risk factors for IgA nephropathy and Henoch-Schönlein nephritis.

There have been several reports suggesting that the deficiency of complement 4 (C4) and/or deletion of C4 genes are the genetic risk factors in patients with IgA nephropathy (IgAN) and Henoch-Schönlein nephritis (HSN). In the current study, we tried to clarify the genetic structure of deleted C4 genes as well as the isotype deficiency of the patients. Also, we investigated the DQB and DRB genes which are located near the C4 genes to identify a possible linkage and to find the associated allele. Our results showed that locus II deletion of C4, not the C4B sequence loss, is a risk factor for these diseases and the deleted gene can be either C4A or C4B. There was no specific isotype deficiency or specific allotype which was significantly increased or decreased in the patients. But, there was an increased frequency of DQA1*0301 gene in the patient group (corrected p = 0.04), which suggests that DQA1*0301 as well as C4 gene deletion could be genetic risk factors for these diseases.

Adult↗
PubMed1996

[CD45 gating for flow cytometric analysis of acute leukemia].

Gating of leukemic cells for immunophenotyping by flow cytometry is currently set on two dimensional display of forward scatter (FSC) and side scatter (SSC). However, this gating method can not descriminate leukemic cells from contaminated normal cells (especially normal lymphocytes). Thus, in this paper, we used CD45 monoclonal antibody to detect leukemic cells (CD45dim cells) in conjunction with SSC parameter. This CD45-SSC gating revealed that this method is very useful in AML and ALL, especially leukemia with low percentage blasts. We recommend that this new gating method should be employed for more accurate immunophenotyping of acute leukemia.

Antibodies, Monoclonal↗
PubMed1995

Effects of complement activation on the expression of CD59 by human mesangial cells.

Human mesangial cells (HMC) were analyzed for their expression of 20-kDa homologous restriction factor (CD59), a glycophospholipid-anchored regulatory protein of the complement cascade. Flow cytometric analysis showed that CD59 was expressed on the HMC membrane and, following the activation of the terminal pathway complement components, CD59 expression on the HMC membrane increased. Northern blot analysis showed that CD59 mRNA levels increased by complement activation. Of interest, CD59 mRNA levels increased by soluble complement activation product, zymosan-activated C8-depleted serum, but not zymosan-activated C5-depleted serum. This effect of soluble complement activation product was due to the presence of the action of C5a. Thus, recombinant C5a increased CD59 mRNA levels. The capacity of CD59 to reinsert into rat E and inhibit C-mediated lysis was inhibited by mAb against CD59 (1F5). Metabolic labeling using [35S]cysteine showed that the molecular mass of CD59 in HMC was 20 kDa. In conclusion, CD59 is present on HMC and the expression of CD59 is controlled by at least two steps of complement activation pathway, C5 and C8.

Antigen-Antibody Complex↗