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Biomedical subjects

K Shimada

Publications and source records attributed to K Shimada.

At least 811 records · Page 45Linked to original sources
PubMed1994

Thrombin generation as an acute effect of cigarette smoking.

The effects of acute smoking on hemostatic functions were investigated in healthy young volunteers. Immediately after the volunteers smoked, a significant increase in blood pressure and heart rate was accompanied by a rise in plasma epinephrine. Fibrinopeptide A and thrombin-antithrombin III complex as markers of thrombin generation in vivo were significantly increased after smoking. The increase in thrombin-antithrombin III complex was significantly correlated with that of plasma epinephrine. Both antigen and activity of tissue plasminogen activator and plasmin-inhibitor complex as markers of fibrinolytic activity in vivo were markedly increased after smoking, whereas D-dimer, plasminogen activator inhibitor antigen, fibrinogen, and both beta-thromboglobulin and platelet factor 4 as markers of platelet activation in vivo were not changed. No effects were observed after sham smoking under exactly identical conditions in the same subjects. Thus thrombin generation was observed as acute hemostatic effects of smoking. Enhanced fibrinolytic response may counteract an increased procoagulant activity. Patients with vascular disease might be more susceptible to a state of disequilibrium in favor of coagulation, which may partly explain a mechanism by which cigarette smoking leads to cardiovascular morbidity and mortality.

Adult↗
PubMed1994

Predictive factors for postoperative recurrence of hepatocellular carcinoma.

BACKGROUND/AIMS: The survival rate for hepatocellular carcinoma after hepatectomy remains unsatisfactorily low because of the high recurrence rate. The purpose of this study was to elucidate predictive factors for postoperative recurrence of hepatocellular carcinoma. METHODS: Univariate analysis and a multiple regression model were used to retrospectively determine the factors potentially related to recurrence in 98 patients with hepatocellular carcinoma who had undergone curative hepatic resection. RESULTS: DNA diploidy, absence of alcohol abuse, and absence of vascular invasion were determined to be independent favorable predictive factors using a multivariate analysis with Cox's proportional hazards model. A predictive index was developed using these three factors according to the following equation: 1.486 x (O = DNA diploidy or 1 = DNA aneuploidy) + 1.138 x (O = absence or 1 = presence of alcohol abuse) + 0.946 x (O = absence or 1 = presence of vascular invasion). This index was used to classify the patients into two groups with good or poor prognosis. The median time for disease recurrence for the two groups was 24.1 and 9.2 months, respectively (P < 0.001). CONCLUSIONS: The results may be useful in the determination of treatment strategies and postoperative follow-up schedules and in the design and analysis of future clinical trials of therapy for hepatocellular carcinoma.

Aged↗
PubMed1994

Involvement of adhesion molecules in human monocyte adhesion to and transmigration through endothelial cells in vitro.

Although the accumulation of monocyte-derived foam cells in the subendothelium is a key step in early atherogenesis, the mechanism responsible for monocyte adhesion to and subsequent transmigration through endothelial cells (ECs) has not been defined fully. We investigated the kinetics and the role played by adhesion molecules in the adhesion and transmigration of human monocytes using an in vitro three-dimensional model system comprising ECs cultured on collagen gels. Monocyte adhesion to untreated EC layers increased with time, reached a maximum after 3 h, and then declined. Monocyte transmigration through untreated EC layers also increased with time and reached a plateau after 3-4 h. Prestimulation of ECs with interleukin-1 beta (IL-1 beta; 25 U/ml) for 4 h enhanced monocyte adhesion (40.7 +/- 1.4%) and transmigration (37.9 +/- 1.6%) significantly compared with the value for untreated EC layers. In unstimulated EC layers, anti-leukocyte function-associated antigen-1 (LFA-1) plus anti-intercellular adhesion molecule-1 (ICAM-1) monoclonal antibodies (mAbs) inhibited monocyte adhesion and transmigration significantly by 19% and 20%, respectively, whereas anti-very late antigen-4 (VLA-4) plus anti-vascular cell adhesion molecule-1 (VCAM-1) mAbs did not. In IL-1 beta-stimulated EC layers, anti-LFA 1 plus anti-ICAM-1 mAbs inhibited the adhesion and transmigration by 32% and 30%, respectively and anti-VLA-4 plus anti-VCAM-1 mAbs did so by 18% and 27%, respectively. These results suggest that the monocyte-EC interaction in unstimulated ECs is mediated, in part, by the LFA-1-ICAM-1 pathway and in IL-1 beta-stimulated ECs, in part, by both LFA-1-ICAM-1 and VLA-4-VCAM-1 pathways.

Antibodies, Monoclonal↗
PubMed1994

Nitric oxide synthesis in rat cardiac myocytes and fibroblasts.

We investigated nitric oxide (NO) synthase activity in cultured neonatal rat cardiac myocytes and fibroblasts upon treatment with interleukin 1 beta (IL-1 beta) and lipopolysaccharide (LPS). Incubation of cardiac myocytes for 24 h with IL-1 beta or LPS caused a significant increase in NO and cGMP production. Simultaneous incubation of IL-1 beta with NG-monomethyl-L-arginine or transforming growth factor beta (TGF-beta) completely inhibited the IL-1 beta-induced NO and cGMP production in cardiac myocytes. In contrast, incubation of cardiac fibroblasts for 24 h with IL-1 beta or LPS showed no significant effect on NO or cGMP production. Addition of IL-1 beta decreased the beating rate of cardiac myocytes, but TGF-beta overcame that inhibition. These observations suggest the presence of iNOS in cardiac myocytes, which is an important regulator of contractile function of the heart.

Amino Acid Oxidoreductases↗
PubMed1994

Decreased Na,K-ATPase gene expression in cardiomyopathic hamster hearts.

We studied Na,K-ATPase mRNA expression in cardiomyopathic (Bio 14.6) and normal (F1b) Syrian hamster ventricles. In Northern blot analysis, Na,K-ATPase alpha 1, alpha 2, alpha 3 and beta 1 isoform mRNAs were detected in 3-week-old Bio 14.6 and F1b hamster ventricles. We then investigated the expression of alpha 1 subunit mRNA in Bio 14.6 hamster ventricles at the ages of 3 weeks prehypertrophic and 30 weeks hypertrophic, and in age-matched F1b hamster ventricles. The alpha 1 subunit mRNA levels in Bio 14.6 hamster ventricles were approximately 50% lower than those in F1b hamster ventricles at both 3 and 30 weeks of age. Na,K-ATPase activity measured in membrane fractions from the ventricles of 3-week-old Bio 14.6 hamsters was also approximately 20% lower than that of F1b hamsters, suggesting that the differences in the mRNA level were associated with the differences in the protein level. We conclude that Na,K-ATPase mRNA expression and enzyme activity are significantly decreased in the hearts of Bio 14.6 hamsters even before the onset of hypertrophy and cardiomyopathy, suggesting that the altered expression of Na,K-ATPase gene is an early event in the pathogenesis of cardiomyopathy in this animal model.

Animals↗
PubMed1994

Production of a group-specific antibody to 1 alpha,25-dihydroxyvitamin D and its derivatives having the 1 alpha,3 beta-dihydroxylated A-ring structure.

To obtain a group-specific antibody to 1 alpha,25-dihydroxyvitamin D and its derivatives having the 1 alpha,3 beta-dihydroxylated A-ring structure, 1 alpha-hydroxy-25,26,27-trinorvitamin D3-24-oic acid was synthesized as a haptenic derivative by a new convenient synthetic route. Three kinds of polyclonal antibodies were elicited in rabbits against the hapten conjugated with bovine serum albumin, and their specificity was examined by cross-reactivities in a radioimmunoassay procedure. One of the antibodies was found to show a suitable binding property by addition of a small amount of the plasma from vitamin D-deficient rats. Dose-response curves with measurable ranges applicable to biological specimens were obtained for 1 alpha,25-dihydroxyvitamin D3, 1 alpha,25-dihydroxyvitamin D2, (24R)-1 alpha,24,25-trihydroxyvitamin D3, (23S,25R)-1 alpha,25-dihydroxyvitamin D3 26,23-lactone, and 22-oxacalcitriol by the radioimmunoassay system using this improved antibody. The antibody will be widely useful for developing profile analyses of 1 alpha,25-dihydroxyvitamin D and its derivatives (metabolites or synthetic analogs) having the 1 alpha,3 beta-dihydroxylated A-ring, as well as immunoassays measuring each of these secosterols individually.

Animals↗
PubMed1994

Primary malignant melanoma of the oral cavity--its histological classification and treatment.

In contrast to Caucasians, the Japanese population has a relatively high incidence of malignant melanoma in the oral cavity, but its classification and treatment has not been established up to now. We present here the detailed clinical and histological features of 14 cases of oral melanoma. In 13 of the 14 patients, the lesions exhibited three phases: a nodular phase consisting of spindle-shaped or epithelioid tumor cells in the submucosa, a pigmented plaque phase consisting of preinvasive tumor cell nests in the lower epithelial layers, and a macular phase consisting of proliferation of dendritic melanocytes without apparent atypia or simple hyperpigmentation in the basal cell layer. The macroscopic and microscopic findings of 13 melanomas corresponded to those of acral lentiginous melanoma of the skin, while the one lesion showing no radial growth phase was classified as nodular melanoma. We devised a new treatment plan for oral melanoma in 1980, which includes surgical excision via an intraoral approach, therapeutic neck dissection, and adjuvant immunochemotherapy. Out of 11 patients treated in this manner, nine had a good outcome without major cosmetic and functional morbidity. This suggests that the prognosis of oral melanoma is not so poor as reported previously if adequate therapy is provided.

Adult↗
PubMed1994

Application of an electrochemical detector with a graphite electrode to liquid chromatographic determination of penicillamine and captopril in biological samples.

A high-performance liquid chromatographic determination of penicillamine and captopril in rat serum, liver and kidney samples is described. An electrochemical detector with a graphite working electrode at a potential of +0.9 V vs the Ag/AgCl reference electrode is used for the detection system. Linear responses of the peak height to the amount of samples injected were obtained in a range of 0.1-500 ng on-column and 0.5-500 ng on-column for penicillamine and captopril with correlation coefficients of 0.997 and 0.995, respectively. Detection limits at a signal-to-noise ratio of 3 were 20 and 300 pg for penicillamine and captopril, respectively. The graphite electrode has a long lifetime of about 4 months with continuous use, even with the high voltage supplied. The analytical application of this method to the determination of penicillamine and captopril in biological samples was successful.

Administration, Oral↗
PubMed1994

Specificity of the polyclonal antibodies raised against a novel 25-hydroxyvitamin D3-bovine serum albumin conjugate linked through the C-11 alpha position.

To obtain a specific antibody for use in 25-hydroxyvitamin D3 [25(OH)D3] immunoassay, a novel hapten-carrier conjugate was prepared by coupling 11 alpha-hemiglutaryloxy-25(OH)D3 with bovine serum albumin (BSA). Three polyclonal antibodies (Ab11) showing high titer and affinity for 25(OH)D3 (Ka = 0.96-2.6 x 10(9) M-1) were elicited in rabbits by repeated immunization with the conjugate. Specificity of the Ab11 was investigated by cross-reactivities with 11 related compounds in a radioimmunoassay using a tritium-labeled antigen and compared with that of conventional antibodies (Ab3) raised against 25(OH)D3 3-hemiglutarate conjugated with BSA. The Ab3 could not discriminate the A-ring modified metabolites [1,25(OH)2D3 (87-290%) and 25(OH)D3 3-sulfate (S) (130-180%)], although the cross-reactivities with the side chain modified metabolites were satisfactorily low [24,25(OH)2D3 (2.3-7.4%), 25(OH)D2 (< or = 1.1%)]. On the contrary, the Ab11 easily discriminated 1,25(OH)2D3 (0.10-2.4%) and 25(OH)D3 3S (< 0.3%), whereas significant cross-reactivities were found with 24,25(OH)2D3 (110-120%) and 25,26(OH)2D3 (66-130%) having a dihydroxylated side chain. These results show that the Ab11 are complementary to the A-ring portion of the 25(OH)D3 molecule which is opposite from the side chain structure recognized by the Ab3. Thus, the Ab11 will compensate for insufficient specificity of the Ab3 and are expected to be a useful tool for the pretreatment of biological samples in the development of various analyses of vitamin D metabolites including specific 25(OH)D3 immunoassays using the Ab3.

Animals↗
PubMed1994

Interleukin 6 gene transcripts are expressed in human atherosclerotic lesions.

Factors controlling the proliferation of vascular smooth muscle cells (SMC) are thought to be key elements in the progression of atherosclerosis. We have previously shown that interleukin 6 (IL-6) stimulates the growth of SMC in vitro and that IL-6 gene transcripts are expressed in atherosclerotic lesions of genetically hyperlipidemic rabbits. To understand the involvement of IL-6 in the development of human atherosclerosis, we investigated IL-6 mRNA expression in atherosclerotic arteries from patients undergoing surgical vascularization, utilizing reverse transcription polymerase chain reaction (RT-PCR) and in situ hybridization analyses. In RT-PCR analysis, the atherosclerotic arteries showed 10- to 40-fold levels of IL-6 mRNA expression over the non-atherosclerotic artery. In in situ hybridization analysis, IL-6 gene transcripts were observed in the thickened intimal layer of atherosclerotic lesions. These results strongly suggest the involvement of IL-6 in the development of human atherosclerosis.

Actins↗
PubMed1994

Nitric oxide synthesis in rat mesangial cells induced by cytokines.

The production of nitric oxide (NO) is increased in experimental nephritis, with NO thought to be an important mediator of cell damage. The cytokines interleukin 1 beta (IL-1 beta), IL-6, IL-8, monocyte chemotactic protein-1 (MCP-1) and transforming growth factor-beta (TGF-beta) are released from mesangial cells in vitro or are expressed in various forms of glomerulonephritis. We investigated the effects of these cytokines on NO synthesis in cultured rat mesangial cells. Incubation of mesangial cells with IL-1 beta (10 ng/ml) for 24 h increased the accumulation of NO and guanosine 3',5'-cyclic monophosphate (cGMP). IL-6, IL-8, MCP-1 and TGF-beta showed no significant effect on the production of NO or cGMP. Transcripts of the inducible NO synthase (iNOS) gene were not detected in unstimulated mesangial cells. However, exposure of cells to IL-1 beta (10 ng/ml) for 24 h resulted in the appearance of iNos mRNA. IL-1 beta-induced NO synthesis was significantly inhibited by NG-monomethyl-L-arginine, cycloheximide, actinomycin D, dexamethasone, and TGF-beta. These results indicate that, of the various cytokines studied, only IL-1 beta stimulates iNOS mRNA accumulation and NO synthesis in mesangial cells. NO may function in an autocrine manner to modulate the glomerular response to inflammation.

1-Methyl-3-isobutylxanthine↗
PubMed1994

Isolation and characterization of retinoic acid-inducible cDNA clones in F9 cells: one of the early inducible clones encodes a novel protein sharing several highly homologous regions with a Drosophila polyhomeotic protein.

To elucidate regulatory mechanisms triggering early mammalian differentiation, 17 retinoic acid (RA)-inducible clones were isolated from 1.4 x 10(5) plaques of cDNA libraries prepared from mouse embryonal carcinoma F9 cells, using the differential plaque hybridization method. Partial nucleotide sequences of these clones demonstrated that ten clones correspond to known genes. Interestingly, only 2 of the 17 clones are among the previously documented up-regulated genes. Therefore, there are many more unidentified genes up-regulated in the course of RA-induced differentiation of F9 cells. As RNAs hybridizable with one of the seven unidentified clones were induced in F9 cells after 3 h of RA treatment, we chose this 'Rae-28' clone as being representative of developmentally up-regulated unidentified clones and its properties were characterized. We determined the Rae-28 cDNA sequence and deduced the RAE-28 protein structure. The deduced RAE-28 protein shared several motifs and highly homologous regions with a Drosophila polyhomeotic protein. As the Drosophila polyhomeotic gene is involved in regulating morphogenesis, the rae-28 gene may participate in regulating early mammalian development.

Amino Acid Sequence↗
PubMed1994

Genetic analysis of HIV-1 during rapid progression to AIDS in an apparently healthy man.

We encountered a case of HIV-1 infection in a previously healthy man, which was characterized by rapid progression to AIDS and death within 7 months in association with high levels of antigenemia throughout the clinical course and no humoral immune response for at least 6 months. Genetic changes of the third variable domain (V3) of the envelope gene of HIV-1 in serum samples were analyzed at four time points during his rapid clinical course. The nucleotide changes were confined to a maximum of three substitutions among 105 nucleotides of the V3 region. A major population of the viral clones in this patient showed one amino acid substitution from aspartic acid (a negatively charged amino acid) to lysine (a positively charged amino acid) at position 30 from the first cysteine of the V3 loop. This substitution was thought to be associated with phenotypic changes, and viruses with this sequence in the V3 region had a strong syncytium-inducing ability in MT-4 cells. It appears that the lack of a humoral immune response accelerated disease progression in our patient and a genetic change that appeared to produce a phenotypic change occurred at an early stage of the disease.

Acquired Immunodeficiency Syndrome↗
PubMed1994

Retention behavior of conjugated metabolites of vitamin D and related compounds in high-performance liquid chromatography.

The retention behavior of sulfates or glucuronides of provitamin D, vitamin D, and 25-hydroxyvitamin D3, together with its fluorescent derivatives, are examined with reversed-phase high-performance liquid chromatography. Inclusion chromatography using cyclodextrin as a mobile-phase additive is also used for this purpose. Conventional reversed-phase high-performance liquid chromatography clearly separates the positionally isomeric conjugates of 25-hydroxyvitamin D3. The addition of the host compound to the mobile phase is effective in separating the pairs of fluorescent derivatives of vitamin-D3 and -D2 conjugates or provitamin-D3 and -D2 conjugates.

Calcifediol↗
PubMed1994

Sodium ion mediated regulation of Na/K-ATPase gene expression in vascular smooth muscle cells.

OBJECTIVE: Na/K-ATPase (Na,K pump) plays an important role in the regulation of intracellular ion composition. The purpose of this study is to determine whether Na+ regulates the levels of mRNA coding for Na/K-ATPase alpha and beta isoforms in cultured rat vascular smooth muscles cells. METHODS: Na/K-ATPase alpha and beta isoform mRNA expression was evaluated by northern blot analysis. The alpha 1 subunit content was determined by ELISA. A luciferase reporter gene assay was performed to study whether the alpha 1 promoter might contain Na+ responsive elements. RESULTS: Na/K-ATPase alpha 1 and beta 1 isoform mRNAs, but not alpha 2 and alpha 3 isoform mRNAs, were expressed in cultured rat vascular smooth muscle cells. Exposure of the cells to 10 microM veratridine, an Na+ channel activator, resulted in two- and threefold increases in alpha 1 and beta 1 mRNA accumulation, respectively, with a maximum at 60 min. The veratridine induced alpha 1 and beta 1 mRNA accumulation was still observed even in the absence of extracellular Ca2+. The increase in alpha 1 mRNA accumulation caused by 10 microM veratridine was associated with a significant increase in alpha 1 subunit protein accumulation. Transfection experiments with chimeric plasmids containing 5'-flanking sequences of alpha 1 isoform gene and luciferase reporter gene showed that 10 microM veratridine caused a threefold increase in luciferase activity. CONCLUSIONS: These results suggest that Na+ stimulates the transcription of Na/K-ATPase alpha 1 and beta 1 isoform genes in vascular smooth muscle cells. The transfection study further supports the premise that Na+ responsive elements are located within the 5'-flanking sequences of alpha 1 isoform gene.

Animals↗
PubMed1994

Expression of intercellular adhesion molecule-1 on rat cardiac myocytes by monocyte chemoattractant protein-1.

OBJECTIVE: Cytokine induction of intercellular adhesion molecule-1 (ICAM-1) on cardiac myocytes may be a critical step in cardiac inflammation associated with acute myocardial infarction and myocarditis. The aim of this study was to investigate the involvement of monocyte chemoattractant protein-1 (MCP-1), a homologue of mouse JE, in the neutrophil-myocyte adhesion in vitro. METHODS: MCP-1/JE and ICAM-1 mRNA expression in cultured neonatal rat cardiac myocytes was evaluated by northern blot analysis. ICAM-1 molecule content on myocytes was determined by ELISA. For adherence assay, myocytes and neutrophils were co-incubated and the number of bounded neutrophils was counted. RESULTS: MCP-1/JE transcripts were not clearly observed in cultured neonatal rat cardiac myocytes; however, its transcripts were clearly detected by exposure to interleukin 1 alpha (100 U.ml-1), lipopolysaccharide (1 microgram.ml-1), or hypoxia (95% N2 + 5% CO2). In ELISA analysis, the expression of ICAM-1 molecules on cardiac myocytes was significantly stimulated by MCP-1 in a dose dependent manner, and the effect of MCP-1 was observed as early as at 6 h. In northern blot analysis, ICAM-1 mRNA expression was constitutively observed in myocytes, and the expression was markedly stimulated by exposure to MCP-1 with a peak elevation at 2 h. In adherence assay, MCP-1 stimulated the adhesion of rat neutrophils to rat cardiac myocytes, and this effect of MCP-1 was inhibited by an anti-ICAM-1 MAb. CONCLUSIONS: These results suggest that cardiac myocytes produce MCP-1, which could in turn promote the adhesion of neutrophils to myocytes via ICAM-1 expression, suggesting the involvement of MCP-1 in cardiac inflammation associated with acute myocardial infarction and myocarditis.

Animals↗