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Biomedical subjects

Y Kobayashi

Publications and source records attributed to Y Kobayashi.

At least 379 records · Page 21Linked to original sources
PubMed2000

Comparative analyses of megakaryocytes derived from cord blood and bone marrow.

Thrombocytopenia is typically observed in patients undergoing cord blood transplantation. We hypothesized that delayed recovery of the platelet count might be caused by defects in the megakaryocytic differentiation pathway of cord blood progenitors. To test this hypothesis, we compared the features of in vitro megakaryocytopoiesis between cord blood progenitors and those in bone marrow cells after isolation of CD34+ cells as progenitors. The proliferative responses of the progenitors in cord blood are higher than those in bone marrow cells in the presence of interleukin (IL)-3, stem cell factor (SCF) and thrombopoietin (TPO). However, the ability to generate mature megakaryocytes was higher in bone marrow progenitors than in cord blood in the same in vitro culture system, when examined by the expression of CD41, polyploidy and proplatelet formation. Furthermore, an earlier induction of c-mpl protein, a receptor for TPO, was observed in the progenitors from bone marrow than in those from cord blood in the presence of SCF and IL-3. Therefore, the ability to generate mature megakaryocytes in bone marrow progenitors is superior to that in cord blood, and the delayed engraftment of platelets after cord blood transplantation might be attributed to the features of cord blood megakaryocyte progenitors.

Antigens, CD34↗
PubMed2000

Involvement of natural killer cells in patients with myelodysplastic syndrome carrying monosomy 7 revealed by the application of fluorescence in situ hybridization to cells collected by means of fluorescence-activated cell sorting.

Monosomy 7 is the most frequent chromosome abnormality among patients with secondary myelodysplastic syndrome (MDS). We used fluorescence in situ hybridization (FISH) and fluorescence-activated cell sorting (FACS) in order to clarify the lineage involvement. Four patients, three with de novo MDS and one with secondary MDS, were enrolled in this study. Monosomy 7 was observed in pluripotent stem cells (CD34(+)Thy-1(+)), and in B (CD34(+)CD19(+)) and T/natural killer (NK) progenitors (CD34(+)CD7(+)). The number of abnormal cells of B (CD19(+)) and T (CD3(+)) cells was below the cut-off value, but approximately 60% of the NK cells (CD3-CD56(+)) contained monosomy 7 in three of the patients.

Aged↗
PubMed2000

Serum interferon-gamma-inducing factor/IL-18 levels in primary biliary cirrhosis.

Primary biliary cirrhosis is an autoimmune disease of the liver in which T helper 1 cytokines predominate over those of T helper 2 in the pathogenesis. Interleukin- 18 (IL-18), for which the gene was recently cloned, is a novel T helper 1 cytokine, which augments interferon-gamma production. We designed this study to clarify the role of IL-18 in primary biliary cirrhosis and to examine whether serum IL-18 level can be a prognostic indicator for the disease. Serum IL-18 levels were measured using an enzyme linked immuno sorbent assay with mouse monoclonal antibodies. Twenty-two healthy volunteers, 31 patients with primary biliary cirrhosis (Scheuer's stage I, 13; II, 10; and IV, 8), 20 patients with autoimmune hepatitis, 11 patients with virus-related liver cirrhosis and six patients with obstructive jaundice were enrolled. Significant differences of serum IL-18 levels were observed between patients with Scheuer's stage IV and those with stage I, or II, virus-related liver cirrhosis and obstructive jaundice (P < 0.05). The IL-18 levels in primary biliary cirrhosis increased according to the disease progression, and fell promptly after living-related liver transplantation. Moreover, serum IL-18 levels in primary biliary cirrhosis were correlated with serum bilirubin concentrations and the Risk scores of the Mayo Clinic prognostic model for the disease. The IL-18 levels observed in patients with autoimmune hepatitis were also elevated, and correlated with the activity of the disease. These results indicate that serum interleukin-18 levels reflect the severity of primary biliary cirrhosis, the activity of autoimmune hepatitis, and may be an additive prognostic indicator in primary biliary cirrhosis.

Autoimmune Diseases↗
PubMed2000

Molecular mechanism of a cross-talk between oestrogen and growth factor signalling pathways.

Oestrogen (E2) plays significant roles in variety of biological events such as the development and maintenance of female reproductive organs, bone and lipid metabolisms. More recently, from study of knock-out mice deficient in oestrogen receptor (ER) alpha and ERbeta it turned out that normal spermatogenesis requires the E2 actions. Furthermore, this female steroid hormone is also well known to be deeply involved in many pathophysiological events such as osteoporosis and cancer development in female reproductive organs. It is particularly well known that most breast cancer is dependent on E2 in its development. Such E2 actions are thought to be mediated through two subtypes of ERs. Growth factors have been shown to synergize in this E2 signalling pathway, although the actual molecular mechanism largely remains unknown. Recently, we found that the MAP kinase activated by growth factors phosphorylates the Ser118 residue of the human ERalpha A/B domain and this phosphorylation potentiates the N-terminal transactivation function (AF-1) of human ERalpha, indicating the possible molecular mechanism of a novel cross-talk between E2 and growth factor signalling pathways. More recently, we have identified a coactivator associating with the hERalpha AF-1 in a MAPK-mediated phosphorylation-dependent manner. In this review, the molecular mechanism of this cross-talk is discussed in terms of the transactivation function of ERs, and their coactivators.

Animals↗
PubMed2000

Molecular analysis of zebrafish photolyase/cryptochrome family: two types of cryptochromes present in zebrafish.

BACKGROUND: Cryptochromes (CRY), members of the DNA photolyase/cryptochrome protein family, regulate the circadian clock in animals and plants. Two types of animal CRYs are known, mammalian CRY and Drosophila CRY. Both CRYs participate in the regulation of circadian rhythm, but they have different light dependencies for their reactions and have different effects on the negative feedback loop which generates a circadian oscillation of gene expression. Mammalian CRYs act as a potent inhibitor of transcriptional activator whose reactions do not depend on light, but Drosophila CRY functions as a light-dependent suppressor of transcriptional inhibitor. RESULTS: We cloned seven zebrafish genes that carry members of the DNA photolyase/cryptochrome protein family; one (6-4)photolyase and six cry genes. A sequence analysis and determination of their in vitro functions showed that these zebrafish cry genes constitute two groups. One has a high sequence similarity to mammalian cry genes and inhibits CLOCK:BMAL1 mediated transcription. The other, which has a higher sequence similarity to the Drosophila cry gene rather than the mammalian cry genes, does not carry transcription inhibitor activity. The expressions of these cry genes oscillate in a circadian manner, but their patterns differ. CONCLUSIONS: These findings suggest that functionally diverse cry genes are present in zebrafish and each gene has different role in the molecular clock.

ARNTL Transcription Factors↗
PubMed2000

Interaction of ribosome recycling factor and elongation factor EF-G with E. coli ribosomes studied by the surface plasmon resonance technique.

BACKGROUND: Ribosome recycling factor (RRF), in concert with elongation factor EF-G, is required for disassembly of the post-termination complex of a ribosome after the release of polypeptides. How RRF dissociates the complex has long been puzzling. Crystal structures of RRF molecules have been solved recently and shown to mimic a transfer RNA (tRNA) shape, which prompted us to examine whether RRF binds to the ribosome as tRNA does. RESULTS: The formation of ribosome complexes on the surface-coupled RRF and elongation factor EF-G of Escherichia coli was monitored in real time with a BIACORE 2000 instrument based on the surface plasmon resonance technique. RRF interacted with 70S ribosomes as well as 50S and 30S subunits, although it interacted preferentially with 50S subunits, which was clearly seen under high but physiological ionic conditions. This 50S interaction was diminished by a single amino acid substitutions for Arg132 of RRF, which did not appreciably affect the protein folding but nullified the activity in vivo and in vitro. Moreover, a set of antibiotics that inhibited the RRF-50S interaction were also inhibitory to the polysome breakdown activity of RRF in vitro. The BIACORE technique also worked very well in demonstrating the action of the antibiotics thiostrepton and fusidic acid, which are inhibitory to the RRF function by freezing the pre- and post-translocation intermediates catalysed by EF-G. CONCLUSIONS: These results suggest that the preferential interplay of RRF with the 50S subunit may be of biological significance, probably reflecting the mode of RRF action. The BIACORE technique proved useful for real-time monitoring of the interaction between the ribosome and translation factors, as well as for screening of potential inhibitors for ribosome recycling factor.

Amino Acid Substitution↗
PubMed2000

Primary choriocarcinoma and human chorionic gonadotrophin-producing giant cell carcinoma of the lung: are they independent entities?

AIMS: Human chorionic gonadotrophin (hCG) is a useful marker for chorionic proliferative disorders, such as choriocarcinoma. Although hCG synthesis in lung cancers is frequent, primary pulmonary choriocarcinoma (PCC) is rare. To clarify the differences between primary choriocarcinoma and hCG-producing giant cell carcinoma (GCC) of the lung, we compared the clinicopathological and immunohistochemical findings of these tumours. METHODS AND RESULTS: Three patients, one with PCC and two with hCG-producing GCC, were included in this study. They were all middle-aged men and habitual smokers. The growth of these tumours and the progression of the clinical courses were extremely rapid, and the patients all died within 8 months after the pulmonary tumours were found. Haemorrhagic appearance was a common macroscopic feature of the specimens obtained. Microscopically, both types of tumours mainly consisted of atypical polygonal cells. While PCC contained many syncytial trophoblast-like multinucleated cells that had strong immunoreactivity for anti-hCG, such cells were relatively few in hCG-producing GCC. These histological and immunohistochemical findings reflected the serum test result for hCG, which was higher in the case of PCC. CONCLUSIONS: There are a few differences between PCC and hCG-producing GCC, as described above. Reliable distinction between them seems to be difficult for pathologists and worthless for clinicians.

Carcinoembryonic Antigen↗
PubMed2000

Analysis of histamine-producing cells at the late phase of allergic inflammation in rats.

To identify histamine-producing cells at the late phase of allergic inflammation, the expression of L-histidine decarboxylase (HDC) was examined in the infiltrating leucocytes in the inflammatory locus. HDC activity and HDC mRNA levels in the infiltrating leucocytes in the pouch fluid of the immunized rats (that were injected with the antigen solution into the air pouch) were increased compared with those in the infiltrating leucocytes of the non-immunized rats. When infiltrating leucocytes collected 8 hr after antigen injection were cultured, histamine production by the cells from the immunized rats was higher than that from the non-immunized rats. In situ hybridization of HDC mRNA revealed that almost all the infiltrating leucocytes of the immunized rats, 4 hr after injection of the antigen, expressed HDC mRNA with high intensity, while those of the non-immunized rats showed only a weak intensity of HDC mRNA. In the immunized rats, approximately 90% of leucocytes infiltrating in the pouch fluid at 4 hr were neutrophils and 8% were monocytes/macrophages. Neither mast cells nor basophils were detected in the infiltrating leucocytes. When rat peritoneal neutrophils were incubated in the presence of 12-O-tetradecanoylphorbol 13-acetate, histamine production was significantly increased. These findings suggest that the leucocytes, mainly neutrophils, infiltrating at the inflammatory locus are responsible for histamine production at the late phase of allergic inflammation.

Animals↗
PubMed2000

Congenic rats for hypertension: how useful are they for the hunting of hypertension genes?

1. Linkage studies have revealed quantitative trait loci (QTL) for blood pressure in the rat genome using genetic hypertensive rat models. To identify the genes responsible for hypertension, the construction of congenic rats is essential. 2. To date, several congenic strains have been obtained from spontaneously hypertensive or Dahl salt-sensitive rats. The results of these studies should be interpreted according to whether the rats carry the whole QTL region or not. 3. After establishing congenic strains, three strategies are possible: (i) an orthodox positional cloning in which, using subcongenic strains, the QTL region is cut down to smaller fragments suitable for physical mapping; (ii) a positional candidate strategy in which candidate genes in the QTL regions are studied; or (iii) physiological studies in which intermediate phenotypes directly associated with the hypertension gene are explored. Several other experimental strategies are also available using congenic strains as new animal models for hypertension. 4. To make the most of advances in DNA technology, the precise evaluation of the phenotypic difference between congenic strains carrying different QTL or between a congenic and parental strain is critical.

Animals↗
PubMed2000

Temporal and spatial dispersion of repolarization during premature impulse propagation in human intact ventricular muscle: comparison between single vs double premature stimulation.

AIMS: This study was performed to determine whether or not the kinetics of action potential duration restitution during double premature stimuli (S3) differ from that during single premature stimuli (S2) in the human intact right ventricle. METHODS AND RESULTS: A monophasic action potential (MAP) was simultaneously recorded from the right ventricular apex (RVA) and outflow tract (RVOT) during programmed ventricular pacing in 11 patients with symptomatic bradyarrhythmias (five males, six females, mean age 58 years). In the five most recent patients, the RV pressure and its dp/dt were also obtained during the protocol. A substantial difference in the restitution of the MAP duration (MAPD) between S2 and S3 was observed at short diastolic intervals (< l00 ms), that is, the restitution curve of S2 showed an early biphasic pattern (upward hump), while such a phenomenon was not seen during the restitution of S3. All the quantitative parameters of MAPD restitution representing its kinetics were significantly greater in S3 than S2. Maximum attainable dispersion of repolarization between the two MAPs was significantly greater during S3 than S2 (76 +/- 17 vs 59 +/- 17 ms, P<0.05) and was mainly caused by the difference in the MAPD difference, thus by the difference in the restitution kinetics of S2 and S3. The dp/dt of the RV pressure was significantly greater during S3 than S2 for all diastolic intervals tested. CONCLUSION: It was concluded that similar to previously reported canine experimental studies, the APD restitution of S3 is substantially different from that of S2 in the human intact ventricle (endocardium).

Action Potentials↗
PubMed2000

Expression of telomerase-associated protein 1 and telomerase reverse transcriptase in hepatocellular carcinoma.

To know whether two protein components of human telomerase (human telomerase-associated protein 1 (hTEP1) and human telomerase reverse transcriptase (hTERT) are useful markers for telomerase activation in human liver diseases, we examined mRNA levels of these and telomerase activity in human liver samples. Twenty-three human hepatocellular carcinomas (HCCs) and corresponding adjacent livers were analysed for hTEP1 and hTERT expression by semiquantitative reverse transcription-polymerase chain reaction, and for telomerase activity by a telomeric repeat amplification protocol assay. Thirteen liver samples (ten HCCs and three dysplastic nodules) that were biopsied with 21-gauge needles were analysed for hTERT expression. hTEP1 was expressed in all samples examined. No correlation between hTEP1 expression and telomerase activity was observed. hTERT expression significantly correlated with telomerase activity (P< 0.001). The positivity of hTERT for HCC and corresponding non-cancerous liver was 100% and 30.4% respectively (P < 0.001). Seventy-four per cent (17/23) of HCCs showed strong hTERT expression, but none of the non-cancerous liver tissues did. hTERT expression of the 21-gauge needle biopsied specimens showed no significant difference from that of the surgical samples. The present study revealed that hTERT is strongly expressed in most HCCs, and that hTERT but not hTEP1 is a key component regulating telomerase activity in human liver.

Adult↗
PubMed2000

Abnormalities of the FHIT gene in human oral carcinogenesis.

The abnormalities of the fragile histidine triad (FHIT) gene in tissue samples of oral squamous cell carcinomas (SCCs) along with several leukoplakias and an erythroplakia were examined to determine whether the FHIT gene is actually a frequent target in vivo for alteration during oral carcinogenesis. Abnormal transcripts of the FHIT gene were found in eight of 15 oral SCCs. Although these abnormal transcripts varied widely, deletion patterns incorporating a deletion of exon 5 were the most common. Loss of heterozygosity (LOH) analysis demonstrated that the abnormal FHIT transcripts found in cancer cells were attributable to abnormalities of the FHIT gene. Abnormal FHIT transcripts were also observed in two of seven premalignant lesions. Interestingly, in the case of one patient with a premalignant lesion showing an abnormal FHIT transcript, subsequent oral SCC developed during a 3-year follow-up period. On the other hand, in the two patients from whom both leukoplakia and SCC samples were taken simultaneously, abnormal FHIT transcripts were found only in the SCCs. Although the functional role of FHIT remains to be clarified, these results suggest that the FHIT alteration is actually involved in carcinogenesis of the oral epithelium.

Acid Anhydride Hydrolases↗
PubMed2000

The bronchoconstrictive action of evodiamine, an indoloquinazoline alkaloid isolated from the fruits of Evodia rutaecarpa, on guinea-pig isolated bronchus: possible involvement on vanilloid receptors.

Evodiamine, a constituent of Evodiae Fructus (Evodia rutaecarpa Benth., Rutaceae), produced a bronchial contraction that is resistant to atropine and abolished by pretreatment with a mixture of the NK1 and NK2 receptor antagonists. Contractile responses to evodiamine were examined in guinea-pig isolated bronchus and compared with those to capsaicin. Both compounds evoked bronchial contraction in a concentration-dependent manner. Maximal contractions for evodiamine and capsaicin were observed at concentrations of 3 microM and 1 microM, respectively. Capsazepine (10 microM), an established antagonist of vanilloid receptor (capsaicin receptor), competitively inhibited the bronchial contraction evoked by evodiamine, suggesting that evodiamine activated vanilloid receptors. Evodiamine (3 microM) and capsaicin (1 microM) produced complete crossed tachyphylaxis. Both compounds desensitized tissues to subsequent additions of either evodiamine or capsaicin. These results suggest that the evodiamine-induced contractile response of the bronchus could be attributed to the resultant tachykinin release from sensory neurons by binding of evodiamine to vanilloid receptors. Rutaecarpine, which belongs to the same indoloquinazoline-type alkaloid as evodiamine, showed neither bronchoconstrictive, desensitizing effects nor vanilloid antagonistic effects at all the concentrations examined (up to 200 microM).

Animals↗
PubMed2000

Expression of apolipoprotein B-100 in isolated human small intestine epithelium.

Apolipoprotein B-48 (apoB48) is synthesized in the small intestine and becomes a component of chylomicrons (CM). Apolipoprotein B-100 (apoB100) is synthesized in liver and becomes a component of both very low density lipoprotein (VLDL) and low density lipoprotein (LDL). To evaluate whether apoB100 is present in the human small intestine, we performed immunohistochemical staining using anti-apoB100 monoclonal antibody (mAb). Jejunal samples stained positive and the granular staining was noted in the supranuclear region of epithelial cells. We also identified apoB100 expression in the epithelial cells by immunoblotting and dot-blotting of PCR-amplified cDNA. In order to exclude submucosal stroma contaminated with blood, we used isolated epithelium from human small intestine obtained by a crypt isolation technique. The results indicate that not only apoB48, but also apoB100 are expressed in human small intestine epithelium. The expression of apoB100 suggests that the dietary VLDL may be synthesized in human small intestine epithelium and converted into LDL, which might play an important role in atherosclerosis.

Apolipoprotein B-100↗
PubMed2000

Serum markers of graft-versus-host disease after bone marrow transplantation.

BACKGROUND: Graft-versus-host disease is one of the major complications after allogenic bone marrow transplantation, but it is not easy to anticipate the onset. OBJECTIVES: The purpose of this study was to determine clinically useful markers of acute graft-versus-host disease. METHODS: We measured the serum levels of tumor necrosis factor-alpha, soluble tumor necrosis factor receptor 1, soluble c-kit, soluble Fas, soluble intercellular adhesion molecule-1, growth-related oncogene protein-alpha, thrombomodurin, and interleukin-16 in 13 patients at 1 to 7 weeks after allogenic bone marrow transplantation. RESULTS: The patients with acute graft-versus-host disease showed a significant increase of tumor necrosis factor, soluble tumor necrosis factor receptor 1, soluble Fas, soluble intercellular adhesion molecule-1, and growth-related oncogene protein-alpha, although there was a decrease of soluble c-kit. The increases of serum soluble tumor necrosis factor receptor 1, intercellular adhesion molecule-1, and growth-related oncogene protein-alpha were preceded by the elevation of soluble Fas. CONCLUSION: The patients with acute graft-versus-host disease had increased serum levels of tumor necrosis factor-alpha, soluble tumor necrosis factor receptor 1, soluble Fas, and soluble intercellular adhesion molecule 1 and a decreased soluble c-kit level. Tumor necrosis factor-alpha and soluble c-kit were shown to be sensitive and specific parameters for graft-versus-host disease after bone marrow transplantation, and soluble Fas was shown to be a predictor of acute graft-versus-host disease after bone marrow transplantation.

Adolescent↗