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Biomedical subjects

F Shimizu

Publications and source records attributed to F Shimizu.

At least 163 records · Page 9Linked to original sources
PubMed1985

Identification and some biochemical properties of the major XBL gene product of bovine leukemia virus.

Using a rabbit antiserum directed against a synthetic oligopeptide whose sequence was deduced from the nucleotide sequence of the XBL gene of bovine leukemia virus, we detected a 38-kDa protein in virus-producing cell lines. In vitro translation of hybrid-selected RNA unequivocally demonstrates that this protein, designated p38(XBL), is indeed encoded by the XBL gene. Unlike the other virus-encoded proteins, however, p38(XBL) resides within the cells without being incorporated into virions. It undergoes no gross post-translational modifications and has a relatively short half-life (5-6 hr) in vivo. Furthermore, cell fractionation combined with pulse-chase experiment reveals that a significant fraction (more than half) of the p38(XBL) localizes to the nucleus of the infected cell after synthesis. We conclude that the XBL gene of bovine leukemia virus is a functional gene encoding a nonvirion protein p38(XBL), which possibly functions within the nucleus of the infected cell to regulate viral or cellular gene expression. p38(XBL) is presumably translated from a doubly spliced, bicistronic mRNA that has the capability to encode another small polypeptide in a different reading frame.

Antibodies, Viral↗
PubMed1985

p27x-III and p21x-III, proteins encoded by the pX sequence of human T-cell leukemia virus type I.

Human T-cell leukemia virus type I (HTLV-I) is an etiological agent of adult T-cell leukemia and has a unique sequence, pX, that contains four possible open reading frames, I-IV. p40x was previously identified as the gene product of frame IV (x-lor) and was suggested to mediate transcriptional trans-activation of the viral long terminal repeats. We have identified two pX gene products, p27x-III and p21x-III, encoded by frame III, which mostly overlapped frame IV. These proteins were detected with rabbit antiserum against the synthetic peptide predicted from the 3' end of frame III. p27x-III is phosphorylated in cultured cells, and the phosphoprotein (pp27x-III) is localized in nuclei; some pp27x-III was tightly bound to nuclear components. p27x-III was detected in a number of cell lines that express other viral antigens, including a cell line previously reported to express only p40x as a viral protein. The function(s) of p27x-III and p21x-III is not known, but the tight binding of pp27x-III to nuclear components suggests that it is associated with regulation of viral gene expression.

Amino Acid Sequence↗
PubMed1985

Studies on the 'linear pattern' in renal glomeruli demonstrated with immunofluorescence.

We have experimentally induced the 'linear pattern' in immunofluorescence: the linear deposition of endogenous immunoglobulin (Ig) along the glomerular basement membrane (GBM) in rats injected with both protamine and nephrotoxic serum. This Ig was demonstrated to have no specific antibody activity against GBM or rabbit serum. Our findings could be of value in the analysis of the mechanism and pathological meaning of the 'linear pattern' of endogenous Ig in immunofluorescence.

Alloxan↗
PubMed1985

Long-term observation of passive Heymann nephritis.

Chronic renal lesion with membranous changes and massive proteinuria similar to human membranous nephropathy was induced in rats through repeated intravenous injections of gamma-globulin fraction of rabbit anti-rat F X 1A antisera (GRAFA) 0.37-1.5 mg/100 g body weight. The injections were administered every 2 or 3 days over a 68-day period for a total of 26 times. It is suggested that a sufficient amount of GRAFA was given to the rats to induce renal lesion, judging from the result that no remarkable differences were observed between the severity of the histopathological and clinical changes in each rat given the various doses of GRAFA. Furthermore, this renal lesion is considered to correspond to human membranous nephropathy morphologically and clinically, judging from the fact that the protein excretion was kept at a plateau, and the capillary lumen was kept almost intact with advanced membranous changes.

Animals↗
PubMed1985

Inhibitory effect of interferon on the production of insulin.

Viral and bacterial infections may produce abnormalities in carbohydrate metabolism in normal subjects and profound changes in glucose homeostasis in insulin-dependent diabetics. Using an RIA with [125]porcine insulin, the effect of rat interferon (IFN) on the production/secretion of immunoreactive insulin (IRI) in cultured cells was investigated. We found that, after incubation of rat insulinoma cells with rat IFN, a decrease in the production of IRI was observed. The decrease correlated with the concentration of IFN and the length of the incubation. IFN also caused a decrease in the production/secretion of IRI from rat pancreatic beta-cells in primary culture. This IFN has all of the properties of IFN including species specificity, and the insulin inhibitory effect cannot be dissociated from the antiviral activity of IFN. These data suggest that one possible explanation for abnormalities in glucose metabolism associated with viral or bacterial infections is that virus-or bacteria-induced production of IFN may alter the concentration of insulin.

Animals↗
PubMed1985

Decreased binding of insulin to erythrocytes in myotonic dystrophy.

Recent several studies have shown that the insulin resistance exists in patients with myotonic dystrophy. Using in vitro radioreceptor assay with 125I-labeled insulin, we evaluated the binding of insulin to erythrocytes in patients with myotonic dystrophy. It was found that there was a decreased binding of insulin to erythrocytes in the patients with myotonic dystrophy. On quantitative analysis, this decrease in binding was found to be the result of a decrease in receptor affinity rather than receptor concentration. There was no evidence that the alteration in insulin receptor affinity was due to hyperinsulinemia. All of 7 patients with myotonic dystrophy also were shown to have an excessive response of endogenous insulin to a glucose challenge. No circulating antibody to insulin was found. These data suggest that a decrease in affinity of insulin receptors may, in part, cause insulin resistance and a compensatory elevation of the plasma insulin concentration in patients with myotonic dystrophy.

Adolescent↗
PubMed1985

Effects of mononuclear phagocyte system modulating agents on Fc and C3 receptors of adherent cells.

Agents which modulate the mononuclear phagocyte system (MPS) were examined for their effects on Fc and C3 receptors of adherent cells (A-cells) as judged by rosette formation. Dextran sulphate, carrageenan, and immune complexes, known as MPS suppressants, reduced the percentage of receptor-positive A-cells, while levamisole, known as a MPS-activator, increased the percentage in vitro. The changes in the percentage of Fc receptor were parallel to those of the C3 receptor in vitro. The effects of these agents were also examined in vivo.

Animals↗
PubMed1985

A nephropathy induced by immunization of rats with EHS tumour.

Immunization of rats with Engelbreth-Holm-Swarm tumour induced a nephropathy immunohistopathologically similar to Heymann nephritis except that IgG was deposited along the tubular basement membranes. Autoantibodies against both brush border and basement membranes of proximal tubules were found in the sera. Immunoperoxidase staining of the tumour cells and absorption studies suggested that the tumour cells produced the FX1A-related antigens. Immunodiffusion analysis suggested that the antigens which induced this nephropathy differed from gp 330 and gp 600 which have been reported to be responsible for Heymann nephritis.

Animals↗
PubMed1985

[Clinicopathological study of a malignant lesion in the remnant stomach].

Thirty-six cases of malignant lesion in the remnant stomach were studied clinicopathologically. Ten had been surgically managed as benign lesions and eight were suspected of being metachronous multiple gastric cancer. The pathological characteristics of the malignant lesions and the operation interval (mostly more than 10 years) were similar in these two groups. Although malignant lesion in the remnant stomach is difficult to differentiate clearly when there is no sufficient histological evidence, the operation interval of more than 10 years can be one of the criteria for differential diagnosis.

Adult↗
PubMed1984

Identification of gag and env gene products of human T-cell leukemia virus (HTLV).

The gag and env gene products of human T-cell leukemia virus (HTLV) were identified with rabbit antisera against the synthetic peptides and a polypeptide produced in Escherichia coli, which corresponded to parts of the proteins predicted from the nucleotide sequence of HTLV [M. Seiki, S. Hattori, Y. Hirayama, and M. Yoshida (1983). Proc. Natl. Acad. Sci. USA 80, 3618-3622]. Viral proteins were detected by immunoprecipitation in two HTLV-producing cell lines. The precursor of gag products was a protein with an apparent molecular weight of 53,000 (Pr53), and was shown to be processed into three mature gag proteins, p19, p24, and p15, in this order, from the 5' end of the gag gene. The processing sites were confirmed to be the same as those predicted from the nucleotide sequence. The env gene product was identified as a glycoprotein of 62,000 Da (gp62), which was processed into gp46 and p20E. All the viral antigens described above were also detected with sera from ATL patients, indicating that all these proteins are expressed in the patients.

Amino Acid Sequence↗
PubMed1984

Effect of short-term exposure to O3 on antibody response in mice.

The effect of short-term exposure to ozone (O3) on antibody response in mice was investigated. BALB/c mice were continuously exposed to 0.4 and 0.8 ppm O3 for 1, 3, 7, and 14 days. Lung weights increased significantly after 3, 7, and 14 days O3 exposure. Spleen weights of mice exposed for 1 and 3 days were decreased compared to those of controls. However, exposure for 7 and 14 days showed no alterations in spleen weight. In the thymus, all O3 exposures markedly decreased its weights. Primary antibody response to sheep red blood cells (SRBC) in the spleens of mice exposed to 0.8 ppm O3 was suppressed in all exposure periods. However, no suppression was observed in primary antibody response to DNP-Ficoll of exposed spleens. These results suggest that the impairment of T-lymphocyte function in spleen and thymus was induced by short-term exposure to 0.8 ppm O3.

Animals↗
PubMed1984

Purification by sucrose density gradient zonal centrifugation and affinity column chromatography of antigenic substances from the livers of mice infected with Tyzzer's disease.

Antigenic substances from livers of mice infected with Tyzzer's disease were purified by means of sucrose density gradient zonal centrifugation and affinity column chromatography using antiserum and checking antigenicity with the complement fixation test. Fractions obtained from zonal centrifugation fell into three main groups with different molecular weights, two of which (Fr. I and Fr. II) positively reacted with antiserum in the complement fixation tests. Both fractions were further purified by affinity column chromatography. The molecular weights of the main antigenic substances derived from Fr. I and Fr. II were determined to be about 52 000 and 66 000, respectively, by means of SDS-PAGE.

Animals↗
PubMed1984

Restoration of antigenicity of tissue antigens, cell-bound immunoglobulins and immune deposits in paraffin-embedded tissue. The influence of fixation and proteolytic enzymatic digestion.

The possibility of preservation and restoration of antigenicity of some antigens in paraffin-embedded tissue was evaluated by direct immunofluorescent technique on deparaffinized sections. Fixation with 96% ethanol-1% acetic acid, 10% neutral buffered formalin and p-formaldehyde was useful for the preservation of tissue antigens and immune deposits, whose antigenicity could be easily restored by trypsin digestion. Neutral buffered formalin was also a satisfactory fixative in immunofluorescent staining on lymphocyte/plasma cell-bound immunoglobulins. Fixation with alcohol-Bouin's fluid showed contrast results; feasible for staining of cell-bound immunoglobulins, but poor for that of glomerular immune deposits. After papain digestion, BSA and lysozyme, antigens of immune complexes, were easily detected in experimental chronic serum sickness glomerulonephritis. Pepsin was more efficient than trypsin in restoring the antigenicity of renal tissue antigens such as fibronectin and polyantigenic basement membrane, but the brush border antigen of the proximal renal tubules was frail to the pepsin digestion. In general, the enzymatic digestion time necessary for the restoration of antigenicity was in parallel with fixation time. Results obtained have shown that deparaffinized sections could be used as satisfactory substrate for immunohistochemistry when proper fixation and efficient proteolytic enzymatic pretreatments were performed.

Animals↗
PubMed1984

Experimental glomerulonephritis induced by human IgG in rats.

Experimental immune complex glomerulonephritis was induced with human IgG (HIgG) in two strains of rats, Wistar-King-Aptekman (WKA) and spontaneously hypertensive rats (SHR). The rats were pre-immunized s.c. with 1 mg of HIgG in Freund's complete adjuvant, and 8 weeks later were given a daily i.v. 2 mg of HIgG injections for 4 weeks. Renal tissue, obtained at weekly intervals after the beginning of i.v. injections, was examined by light, immunofluorescence and electron microscopic tests. SHR developed an endocapillary proliferative glomerulonephritis with heavy proteinuria after the administration of HIgG for 4 weeks. They had massive depositions of HIgG, rat IgG, and rat C3 both in the mesangial area and along the capillary wall. On the other hand, in WKA rats, the proliferative lesions were scarcely seen and the immune deposits were observed almost exclusively in the mesangium. Moreover, urinary protein excretion of these rats was within normal range. In comparison with bovine serum albumin (BSA) nephritis in SHR, HIgG-induced glomerular lesion was relatively mild. This difference seemed attributable to the nature of the HIgG, such as its molecular weight and immunogenicity.

Animals↗
PubMed1984

Monoclonal antibodies to rat renal antigens.

We have developed hybridoma cell lines which secrete monoclonal antibodies to some rat renal antigens, namely the brush border of proximal tubular epithelium and the cytoplasm of tubular cells. The immunoglobulin class of the hybridoma was found to be IgG1. Specific antibody activity against either glomerular basement membrane (GBM) and tubular basement membrane (TBM) or Bowman's capsule and a part of TBM was observed, although these hybridoma cell lines have not yet been successfully established. In particular, the hybridoma secreting antibodies to TBM did not remain stable during antibody production, and was lost during the culture and cloning procedures. These monoclonal antibodies should be of value in research on the pathogenesis of human glomerulonephritis.

Animals↗