Search PubMed⌕ Search

Biomedical subjects

M Kubota

Publications and source records attributed to M Kubota.

At least 325 records · Page 18Linked to original sources
PubMed1994

Murine cerebellar neurons express a novel gene encoding a protein related to cell cycle control and cell fate determination proteins.

We cloned cDNAs of a novel protein (designated V-1) that has been identified from among the developmentally regulated proteins in the rat cerebellum. Protein sequencing analysis (Taoka, M., Yamakuni, T., Song, S.-Y., Yamakawa, Y., Seta, K., Okuyama, T., and Isobe, T. (1992) Eur. J. Biochem. 207, 615-620) and cDNA sequence analysis revealed that the V-1 protein consists of 117 amino acids and contains 2.5 contiguous repeats of the cdc10/SWI6 motif, which was originally found in the products of the cell cycle control genes of yeasts and the cell fate determination genes in Drosophila and Caenorhabditis elegans. In situ hybridization histochemistry revealed that the expression of the V-1 gene is transiently increased in postmigratory granule cells during postnatal rat cerebellar development and thereafter is markedly suppressed, whereas Purkinje cells constitutively express V-1 mRNA. In contrast, cerebellar granule cells of the staggerer mutant mouse continue to express the V-1 gene even when the granule cells of the normal mouse have ceased to express the V-1 gene, suggesting that the expression of the V-1 gene in granule cells is regulated through the interaction with Purkinje cells. On the basis of these results, we postulate that the V-1 protein has a potential role in the differentiation of granule cells.

Amino Acid Sequence↗
PubMed1994

Different effect of thymidine kinase loss on TTP pools; comparison among human leukemia cell lines.

Thymidine kinase (TK)-deficient cells were established from six human leukemia cell lines to evaluate the role of TK in maintaining intracellular TTP pools. The residual TK activities in mutant cells were less than 3% of those of wild-type strains, except for a B-lymphoid cell line, Ball-1 (8.7%). In a promyelocytic leukemia cell line (HL-60), a splenic B cell line (WI-L2) and Ball-1, a mutational loss of TK resulted in a decrease of TTP pools by 80%, 33% and 54%, respectively. On the other hand, in the T cell lines, Molt-3, Molt-4 and CEM, TTP did not show any significant differences between parent and TK-deficient cells. TK-deficient HL-60 cells had, however, comparable levels of dATP, dGTP and dCTP with wild-type cells. An analysis of growth characteristics showed that the decrease of TTP was not due to the change of the cell cycle distribution. These results indicate that TK plays a different role in maintaining TTP pools among human leukemia cell lines.

B-Lymphocytes↗
PubMed1994

Different mode of cell death induced by calcium ionophore in human leukemia cell lines: possible role of constitutive endonuclease.

The mechanism of cell death induced by calcium ionophore, A23187, was investigated in six human leukemia cell lines. Following exposure to 1 microM A23187, the myelogenous cell lines (HL-60, U-937, KG-1) underwent apoptosis within 3 h as determined by their morphology and DNA fragmentation assay. In contrast, T-lymphoblastic leukemia cell lines (Molt-4, Molt-3, CEM) revealed necrotic cell death after 24 h of incubation. However, an initial rise of intracellular free calcium concentrations and growth inhibition after treatment with A23187 were similar in the two cell types. We further showed that an endonuclease capable of mediating internucleosomal DNA fragmentation was constitutively expressed in the cytosol but not in the nuclei of the myelogenous cell lines, although this endonuclease was not detected in either the nuclei or the cytosol of the T-lymphoblastic cell lines. The activation of the endonuclease in myelogenous cells is calcium-independent and has an optimal pH of 7.5-9. It is inhibited by 1 mM zinc ion or 300 microM aurintricarboxylic acid. We propose that this constitutive endonuclease may be related to the susceptibility of myelogenous leukemia cell lines to apoptotic cell death.

Apoptosis↗
PubMed1994

Variable susceptibility to apoptosis induced by calcium ionophore in hybridomas between HL-60 promyelocytic and CEM T-lymphoblastic leukemia cell lines: relationship to constitutive Mg(2+)-dependent endonuclease.

We recently reported that treatment with calcium ionophore, A23187, induces apoptosis in human myelogenous leukemia cells but causes necrotic cell death in T-lymphoblastic leukemia cells. To better understand the underlying mechanisms of such different modes of cell death, we established hybridomas between HL-60 promyelocytic and CEM T-lymphoblastic leukemia cells. The resulting hybridomas were divided into three groups in terms of their susceptibility to apoptosis following exposure to A23187: (1) hybridomas highly sensitive to apoptosis, (2) hybridomas with intermediate sensitivity to apoptosis which occurs later and to a lesser extent, and (3) hybridomas resistant to apoptosis. However, growth inhibition after 72 h of incubation and an initial rise in intracellular free calcium concentrations induced by A23187 were similar in the three groups. Expression of Ca(2+)-independent/Mg(2+)-dependent endonuclease, which had an optimal pH of 7.5-8.5 and was inhibited by Zn2+, was correlated with the susceptibility of the hybridomas to A23187-induced apoptosis. Thus, this endonuclease may play, at least in part, an important role in the induction of apoptosis in leukemia cell lines. Analysis of hybridomas between apoptosis-sensitive and apoptosis-resistant cells is useful in the elucidation of genetic factors which regulate cell death.

Apoptosis↗
PubMed1994

Autoradiographic analysis of [14C]deoxy-D-glucose in thyroid cancer xenografts: a comparative study with pathologic correlation.

An experimental model of thyroid cancer was prepared for evaluating the accumulation of [14C]deoxy-D-glucose ([14C]DG) in thyroid cancer xenografts (AC2). A continuous cell line established from a biopsy specimen of a metastatic thyroid carcinoma possessed the ability to synthesize the cellular protein without increase in cell division after adding bovine TSH in vitro. The histological sections of the xenografts resected from the 131I treated nude mice mainly consisted of structures showing follicular and trabecular growth. Immunohistochemically the cytoplasm of the tumor cells was positive for human thyroglobulin(hTg). These observations provide strong evidence that the AC2 cell originates in the thyroid follicular epithelium. By comparing autoradiographic accumulation patterns of [14C]DG and histopathological examinations, it was found that the uptake of [14C]DG was higher in the granulation tissues surrounding necrosis than in viable tumor cells of trabeculary growing and follicle forming tissues. It is suggested that the degree of [14C]DG content reflects not only tumor cell viability and proliferation but also the inflammatory and degenerative reaction accompanying tumor cell growth.

Animals↗
PubMed1994

Effect of strict metabolic control on glucose handling by the liver and peripheral tissues in non-insulin-dependent diabetes mellitus.

To examine the effect of strict glycemic control on the insulin resistance of non-insulin-dependent diabetes mellitus (NIDDM), we applied euglycemic hyperinsulinemic clamp combined with an oral glucose load (OGL) to nine non-obese subjects with NIDDM and quantitated insulin-mediated glucose uptake by the liver (HGU) and peripheral tissues (PGU) simultaneously before and after 3 to 4 weeks of intimate glycemic control by preprandial regular insulin injections 3 times a day. The glucose infusion rate (GIR) required to maintain euglycemia during the clamp before OGL was considered as PGU. After OGL, the fraction of ingested glucose that is not extracted by the liver enters the systemic circulation and reduces the GIR required for the clamp. HGU was calculated from the difference between the amount of OGL and the cumulative decrements in GIR after OGL and was expressed as the ratio to the amount of OGL (%). Three to 4 weeks after initiation of strict metabolic control, FPG and HbA1c levels significantly improved (9.1 +/- 0.5 vs. 6.4 +/- 0.4 mmol/l, and 11.2 +/- 0.8 vs. 8.3 +/- 0.3%, P < 0.05). HGU significantly increased to 33.1 +/- 9.5 from 14.5 +/- 4.8%, while PGU did not change (38.2 +/- 5.2 vs. 37.4 +/- 3.9 mumol/kg.min). These data suggest that short-term strict metabolic control ameliorates insulin resistance in NIDDM mainly at the hepatic level.

Adult↗
PubMed1994

Somatic mutations at T-cell antigen receptor and glycophorin A loci in pediatric leukemia patients following chemotherapy: comparison with HPRT locus mutation.

Frequencies of somatic mutations in pediatric patients with leukemia were evaluated following intensive treatment at three different loci: the hypoxanthine-guanine phosphoribosyl transferase (HPRT), T-cell antigen receptor (TCR), and glycophorin A (GPA) gene. Thirty-two children with acute lymphoblastic leukemia (ALL), nine children with acute myelogenous leukemia (AML), and 20 age-matched healthy controls were included in the study of mutant frequencies (Mfs) at the HPRT and TCR loci. Among these patients and controls, individuals with heterozygous MN blood type, i.e., 14 children with ALL, three children with AML, and nine healthy controls, served for the further assessment of variant frequency (Vf) at the GPA locus. In ALL patients, geometric mean Mfs and Vfs at these loci were significantly higher than in healthy controls. The high Mf value at the HPRT locus persisted for up to 8 years after the end of chemotherapy. On the other hand, the Mf values at the TCR locus and Vf values at the GPA locus declined gradually with time. In AML patients, on the other hand, the geometric mean Mf only at the TCR locus was significantly higher than in the controls, albeit to a lesser degree than in ALL patients. These data suggest that anti-cancer therapy induces somatic mutations at various loci and that ALL patients are more susceptible to mutagenic intervention than are AML patients.

Adolescent↗
PubMed1994

Prevention of fibrosis reduces enzyme-altered lesions in the rat liver.

A choline-deficient L-amino acid-defined (CDAA) diet led to the development of liver cirrhosis in 100% of male Wistar rats after 16 weeks. In contrast, an ordinary (semipurified) choline-deficient (CD) diet led to the development of liver cirrhosis in only 33.3%. After 16 weeks, the liver hydroxyproline content, which reflects the amount of collagen, increased to a level more than four times higher in rats fed a CDAA diet than in rats fed a choline-supplemented L-amino acid-defined (CSAA) diet. Concurrent administration of a prolyl 4-hydroxylase inhibitor, 2,4-pyridine dicarboxylic acid bis(2-methoxyethyl amide) (HOE 077), to rats fed a CDAA diet reduced this increase in liver hydroxyproline content in a dose-dependent manner for doses up to 200 p.p.m. Microscopically, reduction in the hydroxyproline content of the liver resulted in a reduced number of pseudolobuli and thinner fibrous septa. HOE 077 showed no effect on liver hydroxyproline content in rats fed a CSAA diet. The administration of a CDAA diet for 16 weeks led to a substantial induction of GSTP-positive lesions in the liver. The concurrent administration of HOE 077 reduced the number, average diameter and percent area of GSTP-positive lesions in a dose-dependent manner, in parallel with the reduction in hydroxyproline content. These data suggest that inhibition of fibrosis may limit the development of subsequent neoplasms.

Amino Acids↗
PubMed1994

Bio-histochemical aspects of integrins (alpha 2 beta 1, alpha 6 beta 1) in invasive mammary carcinomas: an immunohistochemical study.

Immunohistochemical expression of integrins was examined in 39 human invasive mammary carcinomas, of which 34.2% and 43.6% expressed integrins alpha 2 beta 1 and alpha 6 beta 1, respectively. Immuno-electron microscopy clearly demonstrated that the integrins were in the cell membrane of the carcinoma cells. Similar expression of integrin alpha 2 beta 1 or alpha 6 beta 1 in both the intraductal component and invasive portion of the same tumor was seen in 76.9% and 85.7% of cases, respectively. This suggested that invasive carcinoma cells retained their integrin expression after invasion through the basement membrane. Reciprocal expression of integrins alpha 2 beta 1 and alpha 6 beta 1 was seen in 20 cases. Expression of alpha 2 beta 1 was seen significantly less frequently in scirrhous carcinoma than in the more differentiated papillotubular or solid tubular carcinoma (Chi-squared test, P < 0.05). Intraductal components of carcinoma were present more frequently in cases expressing integrin alpha 2 beta 1 than in those that were negative. This suggests the potential usefulness of integrins as clinical parameters in the surgical treatment of mammary carcinoma, since recent trials of conservative treatment for mammary carcinoma have focused on the intraductal spread of the tumor cells.

Antigens, CD↗
PubMed1994

A hepatic tumor associated with bilateral renal angiomyolipomas: a variant of angiomyolipoma?

Angiomyolipoma is usually derived from the kidney and composed of well developed vessels, smooth muscle and fat tissue. The liver is the only extra-renal site of angiomyolipoma. A peculiar type of hepatic tumor accompanied by bilateral renal angiomyolipomas is reported here. The tumor was mostly composed of large epithelioid cells and a small part of hyalinized large vessels and foam cell infiltration. Mature adipose tissue was absolutely absent. Epithelioid tumor cells arranged in an alveolar pattern had abundant glycogen and some diastase-resistant periodic acid-Schiff granules without obvious crystals. Immunohistochemical studies revealed that the epithelioid cells were positive for melanoma specific antibody (HMB-45), S-100 protein, aromatic L-amino acid decarboxylase and focally alpha-smooth muscle actin. Many melanosome- or premelanosome-like, electron-dense granules were observed in these cells. Thus, these cells were characterized by differentiation to both immature melanocytes and smooth muscle cells. These epithelioid cells were similar to some cells in the renal angiomyolipomas of the same patient. The hepatic tumor was considered to be a result of monotonous proliferation of the epithelioid cells seen in renal angiomyolipoma. Differential diagnosis of this tumor was discussed.

Actins↗
PubMed1994

Erythromycin improves gastrointestinal motility in extremely low birthweight infants.

Erythromycin (EM) was administered to five extremely low birthweight infants (ELBWI) with delayed enteral feeding to evaluate the clinical effect on severely impaired gastrointestinal motility. Five patients studied responded well to EM administration without any adverse effects during the course. Four patients were given 15-30 mg/kg per day EM intravenously as a loading and thereafter 3-5 mg/kg per day as a maintenance dose. One patient responded well without loading. The infants could be fed enterally 4, 5, 6, 4 and 2 days after the initiation of EM administration, respectively. Erythromycin administration is a safe and useful way to facilitate gastrointestinal motility in ELBWI who require prolonged ventilator support with an increased risk for nutrient deprivation.

Erythromycin↗
PubMed1994

A case of common variable immunodeficiency associated with cyclic thrombocytopenia.

A 12 year old boy was found to be deficient in immunoglobulins (Ig) A, G2 and G4, and common variable immunodeficiency was diagnosed. He also had cyclic thrombocytopenia at intervals of approximately 28-30 days. His bone marrow revealed normocellular with slightly decreased megakaryocytes. In vitro colony assays showed markedly imparied megakaryocytopoiesis, erythropoiesis and granulopoiesis. Platelet-associated IgG was elevated at his thrombocytopenic phase. Direct Coombs' test was repeatedly positive. Although not defined at present, we suggest the autoimmune nature of the disease.

Autoantibodies↗
PubMed1994

In vivo administration of granulocyte colony-stimulating factor promotes neutrophil survival in vitro.

We recently showed that recombinant human granulocyte-colony stimulating factor (rhG-CSF) maintained the viability of human neutrophils in incubation for up to 72 hours. However, it is not known whether rhG-CSF can enhance neutrophil survival in in vivo situations. To clarify this issue, we investigated neutrophil survival in vitro following in vivo injection of rhG-CSF. Neutrophils were obtained from 4 pediatric patients with malignancies and healthy adult volunteers before and after rhG-CSF administration. Neutrophils obtained before rhG-CSF treatment started to undergo apoptosis after 24 h of incubation. In contrast, the survival of neutrophils drawn after rhG-CSF administration increased by approximately 24 h. Concomitantly, the appearance of typical ladder-like DNA fragmentation was delayed. Such an increase in neutrophil survival was inhibited by co-incubation with either H 7 (10 mumol/l) or H 8 (20 mumol/l), which worked as protein kinase C inhibitors. Although our study did not measure neutrophil survival in vivo directly, it provides us with further evidence that rhG-CSF may function to prolong neutrophil life expectancy in vivo.

1-(5-Isoquinolinesulfonyl)-2-Methylpiperazine↗
PubMed1994

Induction of apoptosis in childhood acute leukemia by chemotherapeutic agents: failure to detect evidence of apoptosis in vivo.

This study is designed to investigate whether apoptosis occurs in vivo in pediatric patients with acute leukemia during induction therapy. When patients with common acute lymphoblastic leukemia (cALL) and acute myeloblastic leukemia (AML) were treated with prednisolone (60 mg/m2/day, p.o. or i.v.) and etoposide (150 mg/m2/day, i.v.), respectively, the blast cell counts fell to below 30% and 5%, respectively, in 1 week. However, during this cytoreduction phase, neither morphologically apoptotic cells nor fragmentation of DNA derived from peripheral blast cells were detected at any preparations. On the other hand, cALL but not AML cells spontaneously undergo apoptosis following their culture in vitro. The addition of autologous serum instead of fetal calf serum substantially prevented apoptosis from occurring spontaneously in cALL cells. When cALL and AML cells freshly obtained from patients before therapy were treated in vitro with 10 mumol/l prednisolone and 20 micrograms/ml etoposide, respectively, these cells underwent apoptosis within 6 hours, as determined by a morphological and DNA fragmentation assay. These in vivo and in vitro findings suggest that, although anticancer drugs may induce apoptosis in vivo, these apoptotic cells cannot be detected due to their rapid removal from the circulation.

Adolescent↗