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Biomedical subjects

Tatsuo Nagai

Publications and source records attributed to Tatsuo Nagai.

12 recordsLinked to original sources
PubMed2006

Impact of angiotensin-converting enzyme inhibition on renal cortical nitrotyrosine content during increased extracellular glucose concentration.

OBJECTIVES: Experiments evaluated the hypothesis that angiotensin-converting enzyme (ACE) inhibition suppresses hyperglycemia-induced nitrotyrosine (NT) production in the renal cortex. DESIGN AND METHODS: Rats were untreated (UNTR, n = 6) or received the ACE inhibitor enalapril (20 mg/kg/day; ENAL, n = 6) for 2 weeks. Renal cortical slices were incubated for 90 min in media containing 5 (normal) or 20 mmol/L (high) glucose. Superoxide anion (O2*-) and nitrate + nitrite (NO(X)) levels were measured in the media. Superoxide dismutase (SOD) activity and NT content were measured in the tissue homogenate. RESULTS: In the UNTR group, high glucose increased O2*- and NO(X) production by the renal cortex (P < 0.05 vs. normal glucose). Likewise, NT content and SOD activity of the renal cortex augmented (P < 0.05 vs. normal glucose). In the ENAL group, O2*- production and NT content were glucose-insensitive, but high glucose exerted an exaggerated impact on NO(X) production and SOD activity (P < 0.01 vs. UNTR in high glucose). CONCLUSION: Accelerated NT content in the renal cortex during high-glucose conditions was prevented by ACE inhibitor treatment. It was suggested that, apart from its anti-hypertensive effect, the mechanism of suppressed NT degradation in the renal cortex by the ACE inhibitor enhances both O2*- degradation per se and antioxidative effects including SOD activation.

Angiotensin-Converting Enzyme Inhibitors↗
PubMed2006

Apoptosis and adhesion of hemocytes during molting stage of silkworm, Bombyx mori.

To clarify the regulatory mechanism of the rapid changes in the hemocyte density in the silkworm, Bombyx mori, during ecdysis, we evaluated the relationship between the hemocyte density and the incidence of apoptosis during this stage. We also evaluated the role of the sugar chains on the adhesion of hemocytes by analyzing the effects on the hemocyte density of the injection of enzymes that cut sugar chains and monosaccharides into the body cavity. The hemocyte density was increased in the molting stage and spinning, and then decreased after the ecdysis. During spinning, the diameter of the granulocytes markedly increased, in which fatty granules in the cytoplasm increased, becoming foamy. They were identified to be apoptotic hemocytes using the Hoechst staining and the Comet assay. The decrease in the hemocyte density during spinning was mainly caused by the apoptosis of granulocytes. Next, we focused on the fluctuation of hemocyte density during the molting stage. Examination of the changes in the hemocyte density induced by injecting glycoside hydrolases, neuraminidase, sialic acid, or monosaccharides into the body cavity during the fourth molt stage and the third day in fifth instar larva demonstrated that the alteration of hemocyte density was regulated by the attachment and detachment of hemocytes via a selectin ligand, sugar chains. As with the injection of glycoside hydrolase, neuraminidase, sialic acid and fucose raised the hemocyte detachment, and it was assumed that the selectin ligands include the sialyl Lewis x like sugar chains, the same as mammalian lymphocytes.

Animals↗
PubMed2005

Anti-ribosomal P protein antibody in human systemic lupus erythematosus up-regulates the expression of proinflammatory cytokines by human peripheral blood monocytes.

OBJECTIVE: Autoantibodies to ribosomal P proteins (anti-P antibodies) are detected in 12-16% of patients with systemic lupus erythematosus (SLE) and have been found to be associated with some manifestations of the disease, including lupus psychosis and hepatitis. Recent studies have disclosed that anti-P antibodies react with activated T cells but not with B cells, suggesting possible direct effects of anti-P antibodies on immune regulation. The present study was designed to explore the presence of the epitope recognized by anti-P antibodies on human peripheral blood monocytes. METHODS: Highly purified peripheral blood monocytes obtained from healthy donors were cultured with or without interferon-gamma (IFNgamma) in the presence of either anti-P antibodies purified by affinity chromatography from the sera of patients with SLE or control IgG. RESULTS: Flow cytometry analysis disclosed that fresh (day 0) monocytes did not express the ribosomal P epitope, whereas expression of the ribosomal P epitope was induced on annexin V-negative monocytes after activation through plastic adherence for 48 hours. More important, anti-P antibodies (compared with normal IgG or IgG from SLE patients devoid of anti-P antibodies) enhanced the production of tumor necrosis factor alpha (TNFalpha) and interleukin-6 (IL-6) by activated monocytes. Accordingly, anti-P antibodies also up-regulated the expression of TNFalpha and IL-6 messenger RNA in activated monocytes. Of note, F(ab')(2) fragments of anti-P antibodies, which do not result in Fcgamma receptor (FcgammaR) crosslinking, also effectively up-regulated the expression of TNFalpha and IL-6. CONCLUSION: These results indicate that human peripheral blood monocytes express the ribosomal P epitope upon activation, irrespective of induction of apoptosis. Moreover, the data suggest that anti-P antibodies might modify a variety of inflammatory responses through up-regulation of the expression of proinflammatory cytokines in monocytes, in a manner that does not involve FcgammaR crosslinking.

Autoantibodies↗
PubMed2003

Detection, using a novel method, of a high prevalence of cryoglobulinemia in persistent hepatitis C virus infection.

To elucidate precisely the prevalence and significance of cryoglobulinemia in hepatitis C, we examined the prevalence of serum cryoglobulin (CG) among 232 consecutive hepatitis C virus carriers (23 asymptomatic carriers, 164 with chronic hepatitis, 45 with cirrhosis), 30 consecutive hepatitis B virus carriers and 100 age- and sex-matched healthy volunteers. We used a gel-diffusion procedure that detects CG with greater sensitivity and specificity than the conventional precipitation method. Among the 232 patients, 166 were tested for the presence or absence of CG by the precipitation method also, which showed 60 (36.1%) patients to be positive for CG. On the other hand, 164 of the 232 patients (70.7%) were positive for CG using the diffusion method. 5 (16.7%) of the 30 HBV carriers and 2 (2%) of the healthy volunteers also were positive for CG using the gel-diffusion procedure. CG was detected more frequently among the patients with chronic hepatitis or cirrhosis than the asymptomatic carriers. In spite of the high prevalence of CG positivity, only one patient had symptoms related to cryoglobulinemia. Positivity for CG was not related to viral serogroup, viral load or the presence of antinuclear antibody, but it was related closely to CH50: 58 of 63 (92.1%) patients with lower levels of CH50 were positive for serum CG. In conclusion, cryoglobulinemia is a very common feature of chronic hepatitis C.

Journal Article↗
PubMed2002

Viral infection of infants and children with benign transient hyperphosphatasemia.

In this study, we screened serum samples for transient hyperphosphatasemia (TH) using cellulose acetate membrane electrophoresis over a period of 3 years. In the patients found to suffer from TH, we examined the relationship between the clinical condition and viral infection. The frequency of TH was 0.26%, and all of the cases detected were in infants or young children. The female to male ratio of TH was 1.29/1. While there was no clear seasonal fluctuation or periodicity in the appearance of TH, two peaks were recognized in spring and autumn. Research on the clinical manifestations clarified that most of the TH cases had infectious diseases of the upper airways accompanied by symptoms of fever and diarrhea. We examined antibody titers for viruses causing upper airway infectious diseases and identified antibodies for enteroviruses such as Echo 22, Entero 71, and Coxsackie B4. Our results suggested that TH might be caused by an infection of the enterovirus group.

Age Distribution↗