Search PubMed⌕ Search

Biomedical subjects

T Yoshimura

Publications and source records attributed to T Yoshimura.

At least 433 records · Page 24Linked to original sources
PubMed1993

Relationship between resting cytosolic Ca2+ and responses induced by N-methyl-D-aspartate in hippocampal neurons.

Cytosolic calcium concentrations ([Ca2+]i) in cultured hippocampal neurons from rat embryos were measured using fura-2. Neurons with higher resting [Ca2+]i showed greater [Ca2+]i responses to N-methyl-D-aspartate (NMDA) and K+ depolarization. There was a strong relationship between resting [Ca2+]i and the maximal changes in [Ca2+]i (delta[Ca2+]i), which fit the our proposed equation to describe this relationship.

Animals↗
PubMed1993

Antibodies to macrophage stimulating protein (MSP): specificity, epitope interactions, and immunoassay of MSP in human serum.

Macrophage stimulating protein (MSP) is a member of a family of proteins characterized by a triple disulfide loop structure (kringle). We developed antibodies to human MSP for detection in Western blots, quantification in biological fluids, and neutralization of activity. Immunogens included native MSP, reduced and alkylated alpha and beta chains, and peptides of MSP regions with minimal sequence similarity to other kringle proteins. We found three antibody categories based on interaction with the following types of epitope: primary sequence, discontinuous (dependent on disulfide bonds), and cryptic (not exposed in native MSP). None of the antibodies reacted with related kringle proteins. A specific sandwich ELISA was developed for measuring human MSP. The mean serum concentration was 4 nM. Serum MSP did not increase over a 24-h period in response to intravenous lipopolysaccharide, indicating that MSP is not an acute phase protein. These findings are consistent with the hypothesis that regulation of MSP activity is by conversion of pro-MSP to MSP rather than by rapid changes in rates of synthesis.

Amino Acid Sequence↗
PubMed1993

Effect of myasthenic IgG on degradation of junctional acetylcholine receptor.

We investigated the effect of the IgG from patients with myasthenia gravis (MG) on the degradation of normal rat junctional acetylcholine receptor (AChR) labeled with 125I-alpha-bungarotoxin (BuTx) and calculated the degradation rate (DR). The DR for the IgG from these patients was significantly higher than that from healthy volunteers and patients with other autoimmune diseases. For MG, DR was significantly correlated with the severity of the disease but not with anti-AChR antibody titer. DR was accelerated by IgG from patients with generalized MG whose antibody titers were in the normal range and by IgG from patients with ocular MG. These results indicate that measurement of the DR of junctional AChR in normal rats is more closely correlated with the severity of the disease than is measurement of anti-AChR antibody and that the former is a sensitive and confirmatory method for evaluating MG.

Adolescent↗
PubMed1993

Monocyte chemoattractant protein-1 (MCP-1) in inflammatory joint diseases and its involvement in the cytokine network of rheumatoid synovium.

Macrophages infiltrated into synovium play an important role in joint destruction in inflammatory joint diseases. In this study we focused on the production of monocyte chemoattractant protein-1 (MCP-1), a recently identified monocyte chemotactic protein, by inflammatory synovium. Synovial fluid (SF) from rheumatoid arthritis (RA), osteoarthritis, gout, and traumatic arthritis contained MCP-1. MCP-1 was produced in the synovium of patients with RA and other inflammatory joint disease in in vitro culture systems; differences in the amounts produced were not significant. Synovial MCP-1 production in RA was further investigated. Levels of MCP-1 were significantly correlated with levels of IL-1 beta, IL-6, and IL-8 in the culture supernatants of synovia from RA. Using immunohistochemical techniques, MCP-1 was detected in the lining and sublining cells and in the vascular endothelial cells of rheumatoid synovia. Rheumatoid synovia with active inflammation were stained more intensely by anti-MCP-1 antibody than were those with weak or inactive inflammation. IL-1 beta and TNF-alpha stimulated the expression of MCP-1 mRNA and de novo MCP-1 synthesis by cultured synovial cells. These results suggest the production of MCP-1 by synovium of various inflammatory joint diseases. In rheumatoid synovium, a cytokine network involving MCP-1 and other proinflammatory cytokines (IL-1 beta, IL-6, IL-8, and TNF-alpha) contributes to the immunopathogenesis of RA.

Arthritis↗
PubMed1993

Secretion of monocyte chemoattractant protein-1 (MCP-1) by human mononuclear phagocytes.

Concentrations of MCP-1 and NAP-1 in culture fluids of human leukocytes were measured by sandwich ELISA. PPD caused PBMC's from tuberculin-sensitive subjects to secrete MCP-1 and NAP-1. PPD did not stimulate secretion by cells from a tuberculin-negative subject. Since the amounts secreted were more than could be produced by the few PPD-sensitized lymphocytes in the culture, we postulate that other cells were stimulated to secrete these chemoattractants. This study evaluated secretory capacity of one of the cell types in the PBMC culture. Unstimulated monocytes did not secrete MCP-1 or NAP-1. In order of increasing effect, IL-2 + IFN gamma, IL-1 alpha, and LPS caused monocyte secretion of MCP-1. The rank order for NAP-1 secretion was the same. TNF alpha did not cause secretion of MCP-1, but caused about the same amount of NAP-1 secretion as IL-2 + IFN gamma. Composition of the culture medium was especially critical for LPS-induced secretion of MCP-1, which was greatly enhanced by FCS and by Iscove's DMEM compared to RPMI 1640. IL-4 inhibited LPS-induced secretion of both MCP-1 and NAP-1. Secretory patterns were also a function of mononuclear phagocyte phenotype. LPS-induced secretion of MCP-1 was much greater for monocytes cultured several days in CSF-1 than for freshly isolated monocytes. LPS stimulation of bronchoalveolar macrophages caused NAP-1 secretion, but no secretion of MCP-1 above a relatively low baseline level.

Chemokine CCL2↗
PubMed1993

Chromosomal location and structure of amplicons in two human cell lines with coamplification of c-myc and Ki-ras oncogenes.

Gene amplification is a major mechanism through which oncogenes and genes responsible for drug resistance are overexpressed in neoplastic cells, and several models for structure of amplified units (amplicons) are postulated. In order to identify consistent changes associated with oncogene amplification, we analyzed chromosomal location and physical distance of amplicons of two independent human cell lines that have coamplified c-myc and Ki-ras oncogenes. In one cell line, KHC287, amplified c-myc genes were localized in two chromosomes and Ki-ras in three chromosomes. One marker chromosome was almost entirely encompassed by both amplified genes. In the other cell line, Lu-65, both of the amplified genes shared the same locus, on chromosome 12q+. The two genes, however, are more than 1500 kb apart in both cell lines. The above findings indicate that two different amplified genes became associated on one chromosome in two independent cell lines. This suggests that a common mechanism is associated with chromosomal rearrangements affecting different amplified genes.

Chromosome Mapping↗
PubMed1993

Nuclear DNA content as a prognostic predictor in carcinoma of the pancreas.

Eighty-six patients with carcinoma of the pancreas were studied retrospectively. Paraffin-embedded specimens and flow cytometry were used to evaluate the accuracy of the measurement of nuclear DNA as a predictor of the postoperative prognosis. From the series of 86 patients, 72 with a diagnosis of tubular adenocarcinoma (Japanese classification) were selected, and their DNA ploidy pattern and clinical and pathological features were correlated; 52.3% of the 86 patients and 52.8% of the 72 tubular adenocarcinoma patients showed DNA aneuploidy. Histological examinations of the tubular adenocarcinomas showed 42.9% DNA aneuploidy in well differentiated, 56.8% in moderately differentiated, and 71.4% in poorly differentiated types. The DNA ploidy showed a statistically significant positive correlation with the T category. The presence or absence of retroperitoneal invasion was thought to be the most important prognostic factor. Cumulative survival rates showed that the prognosis for patients with retroperitoneal invasion and DNA aneuploidy was significantly worse than for those with DNA diploidy or those without retroperitoneal invasion.

Adenocarcinoma↗
PubMed1993

Serial changes in atrial and brain natriuretic peptides in patients with acute myocardial infarction treated with early coronary angioplasty.

To examine the role of brain natriuretic peptide (BNP) in acute myocardial infarction (AMI), we measured the plasma concentration of immunoreactive (ir) BNP together with that of atrial natriuretic peptide (ANP) over the 4-week course of AMI in 16 patients treated with early coronary angioplasty. Both the plasma ir-ANP and ir-BNP levels were increased on the first day of the infarction compared with the values in normal subjects. During the clinical course of the infarction, the plasma ir-ANP concentration soon decreased, while the plasma ir-BNP level remained elevated at 2 weeks after the infarction, also exhibiting a high level at 4 weeks. Plasma ir-BNP levels on day 1 or days 14 and 28 were inversely correlated with left ventricular ejection fraction obtained by left ventriculography at the acute or chronic phase, respectively. Plasma ir-BNP concentrations on days 14 and 28 were positively correlated with the maximal myosin light chain I level, an indicator of infarct size. These observations suggest that the plasma ir-BNP level increased to compensate for the ventricular dysfunction associated with the size of the infarct in AMI. BNP may act as a cardiac hormone in AMI, differing somewhat from ANP in its synthetic, secretory, or clearance behavior.

Angioplasty, Balloon, Coronary↗
PubMed1993

An efficient synthesis of 4 beta- and 6 alpha-hydroxylated bile acids.

An efficient method for the preparation of 4 beta- and 6 alpha-hydroxylated bile acids has been developed. It involved a highly stereoselective acetoxylation at the 4 beta and 6 alpha positions of 3- and 7-oxo bile acids, respectively, with lead tetraacetate in the presence of boron trifluoride etherate in acetic acid. Reduction of the resulting alpha-acetoxy ketones with sodium borohydride or tert-butylamine borane complex, and alkaline hydrolysis, provided the desired bile acids in good yields.

Acetates↗
PubMed1993

Detection of monocyte chemoattractant protein-1 in human atherosclerotic lesions by an anti-monocyte chemoattractant protein-1 monoclonal antibody.

The infiltration of blood monocytes into the subendothelial space is thought to be one of the most important pathologic events in early atherogenesis. To examine the mechanism of monocyte migration in early atherosclerotic lesions we investigated immunohistochemically the production of monocyte chemoattractant protein-1 (MCP-1) in various atherosclerotic lesions, including diffuse intimal thickening, fatty streaks, and atheromatous plaques, obtained during autopsies of patients of various ages. A highly specific anti-MCP-1 monoclonal antibody that does not cross-react with neutrophil-activating, attractant protein-1/interleukin-8 or platelet proteins that have an amino acid sequence similar to MCP-1 was used to localize MCP-1 in situ. To characterize the cells constituting the atherosclerotic lesions a panel of monoclonal and polyclonal antibodies that are specific to smooth muscle cells (HHF-35), monocyte/macrophages (HAM56, Leu-M3, Leu-M5, EBM11, and PM-2K), and endothelial cells (anti-von Willebrand factor) was used. Double immunohistochemical staining with anti-MCP-1 and one of the cell type-specific antibodies was performed to identify the nature of MCP-1-positive cells. Endothelial cells stained positively for MCP-1 in nine of 14 diffuse intimal thickening lesions. Scattered macrophages in thickened intima also were positive for MCP-1. Endothelial staining of MCP-1 was observed in 14 of 21 fatty streak lesions. Subendothelial macrophages were strongly stained for MCP-1 in all fatty streak lesions examined. Subendothelial macrophages were stained for MCP-1 in atherosclerotic plaques; however, endothelial cells were only slightly positive for MCP-1. A few smooth muscle cells in the intima were positive for MCP-1 in atheromatous plaques. From these results it is concluded that the cell populations positive for MCP-1 are different in early and advanced atherosclerotic lesions, and that the endothelial cells and subendothelial macrophages are considered to be the major sources of MCP-1 in early atherosclerotic lesions.

Adolescent↗
PubMed1993

A direct enzyme immunoassay for 18-hydroxycortisol in urine: a new tool for screening primary aldosteronism.

A microplate enzyme immunoassay has been developed for the measurement of 18-hydroxycortisol in urine. An antiserum was produced by immunization of rabbits with a 3-O-(carboxymethyl)oximino-18-hydroxycortisol-bovine serum albumin conjugate. IgG was isolated from the antiserum and was biotinylated. Newly synthesized p-nitrophenyl ester of the oxime was used for the preparation of steroid-horseradish peroxidase conjugate. After an incubation of diluted urine samples (or standards) and the steroid-enzyme conjugate with the biotinylated antibody, the resulting antigen-antibody complex was separated by adding a portion of the reaction mixture into the avidin-coated microtiter plate. Peroxidase bound to solid phase was measured colorimetrically. The standard curve was linear from 0.25 to 10 ng/well. Intra- and interassay coefficients of variation were 5.5-8.8 and 7.8-8.2%, respectively. The assay was specific except for 18-hydroxycortisone with minor cross reaction. Urinary 18-hydroxycortisol excretion ranged 836-7460 and 26-696 nmol/24 h, respectively, in patients with primary aldosteronism (n = 8) and in control subjects (n = 40). This simple and rapid (< 4 h) assay is suitable for screening patients with primary aldosteronism.

Animals↗
PubMed1993

Site-directed mutagenesis of a hexapeptide segment involved in substrate recognition of phenylalanine dehydrogenase from Thermoactinomyces intermedius.

Phenylalanine dehydrogenase from Thermoactinomyces intermedius and leucine dehydrogenase from Bacillus stearothermophilus show a 59% sequence similarity in their substrate-binding domains, although their substrate specificities are different. We prepared a phenylalanine dehydrogenase mutant enzyme whose inherent hexapeptide segment (124F-V-H-A-A-129R) in the substrate-binding domain was replaced by the corresponding part of leucine dehydrogenase (M-D-I-I-Y-Q) in order to investigate the mechanism of substrate recognition by phenylalanine dehydrogenase. The catalytic efficiencies (kcat/Km) of the mutant enzyme with aliphatic amino acids and aliphatic keto acids as substrates were 0.5 to 2% of those of the wild-type enzyme. In contrast, the efficiencies for L-phenylalanine and phenylpyruvate decreased to 0.008 and 0.035% of those of the wild-type enzyme, respectively. These results suggest that the hexapeptide segment plays an important role in the substrate recognition by phenylalanine dehydrogenase.

Amino Acid Oxidoreductases↗
PubMed1993

MCP-1 mRNA expression in basal keratinocytes of psoriatic lesions.

In addition to hyperproliferation of keratinocytes, psoriasis is characterized by pronounced leukocytic infiltration. In contrast to the epidermal localization of neutrophils and T lymphocytes, macrophages are almost exclusively restricted to the dermal compartment. By immunohistologic analysis, these dermal macrophages were mainly encountered in the papillary dermis and arranged along the rete ridges in close proximity to proliferating keratinocytes. Monocyte chemoattractant protein (MCP-1) anti-sense RNA probes yielded abundant signals over the proliferating basal keratinocytes of the tips of the rete ridges, and, to a lesser extent, in cells in the papillae. Thus, the strongest MCP-1 message in psoriatic lesions is found above the dermal-epidermal junction and this may explain the characteristic sub-basal distribution of dermal macrophages. These results suggest that MCP-1 is important in regulating the interaction between proliferating keratinocytes and dermal macrophages in psoriasis pathogenesis.

Antigens, CD↗
PubMed1993

Detection of Mycobacterium tuberculosis in clinical specimens by polymerase chain reaction and Gen-Probe Amplified Mycobacterium Tuberculosis Direct Test.

The polymerase chain reaction (PCR) using oligonucleotides based on the repetitive sequence (IS986) of Mycobacterium tuberculosis as a primer and the Gen-Probe Amplified Mycobacterium Tuberculosis Direct Test (MTD), which combines an M. tuberculosis rRNA amplification method with the hybridization protection assay format, were evaluated for detection of M. tuberculosis in clinical samples. The detection limits of these two assay systems based on nucleic acid amplification for cultured M. tuberculosis were less than 10 cells per reaction. A total of 135 sputum specimens were examined by the two assay systems. The PCR and the MTD systems for detection of M. tuberculosis gave overall positivity rates of 84.2% (32 of 38) and 91.9% (34 of 37), respectively, as compared with 71.9% (23 of 32) by smear and 96.9% (31 of 32) by culture in the liquid medium MB-Check. Procedures for sample preparation used in the two methods were different. Although the sensitivities of the PCR and MTD appeared to be similar to that of culture with the MB-Check system, the two methods based on nucleic acid amplification should be very useful for rapid detection of M. tuberculosis infections without the long time required for culture of M. tuberculosis.

Bacteriological Techniques↗
PubMed1993

LPS-induced MCP-1, IL-1 beta, and TNF-alpha mRNA expression in isolated erythrocyte-perfused rat kidney.

The capacity of the lipopolysaccharide (LPS)-stimulated isolated erythrocyte-perfused rat kidney (IEPK) to produce monocyte chemoattractant protein-1 (MCP-1), interleukin-1 beta (IL-1 beta), and tumor necrosis factor-alpha (TNF-alpha) mRNA was investigated. The IEPK was chosen to exclude the influence of circulating neutrophils and monocytes that can produce both these mediators when exposed to LPS. The control minimal LPS group (LPS < 10 pg/ml) showed a small increase in mRNA expression for MCP-1, IL-1 beta, and TNF-alpha in the cortex and medulla after 80 min of perfusion when compared with the unperfused left kidney in which no IL-1 beta or TNF-alpha mRNA and only minimal amounts of MCP-1 mRNA were detected. LPS stimulation (1 microgram/ml for 40 or 80 min) increased MCP-1, IL-1 beta, and TNF-alpha mRNA expression, which was found predominately in peritubular capillary endothelial cells by in situ hybridization. The changes were not due to a marked perturbation of LPS on renal hemodynamics. The renal vascular resistance (RVR) remained constant (40 min LPS exposure) or increased only slightly during the last 5-10 min (80 min LPS exposure) compared with a progressive increase in RVR of the minimal LPS group. The hemodynamic effects of LPS on the IEPK appear to counteract the gradual increase in RVR seen in the minimal LPS group.

Animals↗
PubMed1993

Diagnosis of drug allergy by the lymphocyte stimulation test with the MTT [3-(4,5-dimethyl thiazol-2-yl)-2,5-diphenyl tetrazolium bromide] assay.

The lymphocyte stimulation test (LST) is one of the most useful laboratory tests for the identification of allergy to a specific drug. The present study was conducted to examine utility of the LST using the [3-(4,5-dimethyl thiazol-2-yl)-2,5-diphenyl tetrazolium bromide] (MTT) assay as a method for diagnosing drug allergy. The basic experimental conditions for the MTT assay were determined by using CTLL cells from human T-lymphoma, dependent on IL-2, and human peripheral blood lymphocytes. The amount of MTT needed was 0.5 mg per well and the peak maximum of MTT formazan was close to 565 nm. The blastogenesis of the lymphocytes was expressed as a Stimulation Index (SI). The value of the SI was almost constant at cell numbers ranging from 5 x 10(5) to 1 x 10(6) cells/ml. The SI of some drugs using normal peripheral blood lymphocytes was less than 1.3. We used the MTT assay in the LST to examine the allergenicity of 83 drugs which were used in 43 cases of suspected drug-induced hepatitis. The range of SI was 0.92-2.02. An SI of 1.2 or more was seen in 62.8% of cases, 1.3 or more in 51.2% of cases, and 1.4 or more in 41.9% of cases. There were 26 drugs with SI greater than 1.3. Seven of these were antibiotics, while the rest included antihypertensives, analgesics, psychotropics, antiallergics and antiepileptics. This method is extremely well suited for the diagnosis of drug allergy in a clinical situation. The greatest benefit of the MTT assay is that the complete test procedures can be carried out in a general laboratory.

Adult↗
PubMed1993

Treatment of myasthenia gravis: a comparison of the natural course and current therapies.

Ninety-five patients with generalized myasthenia gravis were followed for 10 years to evaluate the long term effects of prednisolone, thymectomy, or both, and they were compared with a group only with anticholinesterase treatment. Only 15.0% of the patients with anticholinesterase alone had showed improvement 10 years after the onset, but more than 60% of those treated with prednisolone, thymectomy, or both showed improvement. Especially thymectomy induced complete remissions at 10 years after surgery in more than 20% of the patients. There was no difference between the histology of the thymi and clinical severity, or anti-acetylcholine receptor (AChR) antibody titer. In patients who showed improvement classified "good" of higher 10 years after thymectomy with or without prednisolone, anti-AChR antibody titers swiftly decreased to 37.8% of the value before surgery, and remained low thereafter. This result suggests that the marked decrease in anti-AChR antibody titers within 1 month after thymectomy is a favorable prognostic sign in myasthenia gravis patients who have undergone thymectomy.

Adolescent↗