Biomedical subjects

M Date

Publications and source records attributed to M Date.

At least 19 recordsLinked to original sources

PubMed2000

Single-strand conformation polymorphism analysis on the delta-sarcoglycan gene in Japanese patients with hypertrophic cardiomyopathy.

To elucidate the etiology of hypertrophic cardiomyopathy (HC) in humans, we analyzed the delta-sarcoglycan gene (SG), which is reported to be the causal gene for HC in the Syrian hamster BIO14.6. We performed polymerase chain reaction (PCR) single-strand conformation polymorphism (SSCP) and nucleotide sequence analyses on the delta-SG in 102 patients with HC. SSCP was detected in exon 2 of the gene, but not in the other exons. The direct sequencing analysis of exon 2 revealed a C-->T substitution at nucleotide residue 84 (TAC-->TAT) with no amino acid alteration (Tyr-->Tyr). There were no significant differences in allele frequencies of C/T between the patients with HC and the control group. Patients with HC were classified into 4 subgroups: obstructive HC, nonobstructive HC, apical HC, and familial HC. The allele frequency of C/T polymorphism in each of these groups was compared with that of the control group. The obstructive HC group showed a significantly greater frequency of the allele T than in the control group (31.6% vs 15.1%, RR = 2.6, p = 0.023). No other significant differences were observed. Thus, amino acid alteration in delta-SG may not be a common cause of HC in Japanese patients.

Adult↗

PubMed2000

Autocrine stimulatory mechanism by transforming growth factor beta in human hepatocellular carcinoma.

The serum concentration of transforming growth factor beta (TGF-beta) is elevated as tumors progress in hepatocellular carcinoma (HCC) patients. In this study, we examined whether modulation of tumor-derived TGF-beta signal transduction contributes to malignant progression. We investigated the production of TGF-beta1, the biological effects of TGF-beta and neutralizing antibody on HCC cells, activation of Smad 2, Smad 3, and Smad 4, induction of antagonistic Smads (Smad 6 and Smad 7), and promoter activities of two target genes, plasminogen activator inhibitor type 1 (PAI-1) and p15INK4B. In human cell lines HCC-M and HCC-T, TGF-beta accelerates their proliferation. Smad 2 was activated constitutively by an autocrine mechanism, because in the absence of exogenous TGF-beta, a high level of Smad 2 phosphorylation, induction of PAI-1 transcripts, and nuclear localization of Smad 2 were observed. This constitutive activation of Smad 2 was, at least in part, attributable to the lack of induction of antagonistic Smads by TGF-beta. However, Smads activated by tumor-derived TGF-beta constantly suppressed p151NK4B expression. In addition, 3 of 10 human HCC tissues showed nuclear localization of Smad 2 and low mRNA levels of p15INK4B and antagonistic Smads but a high level of PAI-1. Our observations suggest that this constant suppression of the p15INK4B gene could be involved in the malignant progression of HCC.

Autocrine Communication↗

PubMed2000

Differential regulation of activin A for hepatocyte growth and fibronectin synthesis in rat liver injury.

BACKGROUND/AIMS: Both hepatocyte growth and production of extracellular matrix such as fibronectin are essential for liver regeneration. Although activin A is reported to inhibit DNA replication in rat hepatocytes, the role of activin A for liver regeneration after acute injury has not been fully assessed. This study investigated the mechanism by which hepatocyte growth is regulated by activin A during liver regeneration and the effects of activin A on extracellular matrix production. METHODS: The mRNA for betaA subunit of activin A and activin receptors in hepatocytes and hepatic stellate cells after CCl4 administration were studied by Northern blotting. Binding of 125I-activin A was tested in these cells. Effects of activin A were examined by DNA, collagen and fibronectin synthesis. RESULTS: betaA mRNA was expressed in quiescent hepatocytes, and this expression peaked 12 h after CCl4 administration. Activin receptor mRNAs and cross-linked ligand/receptor complexes were expressed in hepatocytes and hepatic stellate cells However, these levels decreased specifically in hepatocytes at 24 h and had normalized by 72 h. The down-regulation of activin receptor was also observed after partial hepatectomy. Antiproliferative response to activin A decreased in hepatocytes at 24 h. Activin A stimulated production of fibronectin by hepatic stellate cells, but the synthesis of collagen was only slightly elevated in hepatic stellate cells following activin stimulation. CONCLUSIONS: The down-regulation of activin receptors in hepatocytes may be partly responsible for these cells becoming responsive to mitogenic stimuli. The increase of activin A at the early stage of liver injury has the potential to contribute to the regulation of fibronectin production in hepatic stellate cells.

Activin Receptors↗

PubMed2000

Regulatory mechanisms for transforming growth factor beta as an autocrine inhibitor in human hepatocellular carcinoma: implications for roles of smads in its growth.

Transforming growth factor beta (TGF-beta) initiates signaling through heteromeric complexes of transmembrane type I and type II serine/threonine kinase receptors. Activated TGF-beta type I receptor phosphorylates receptor-regulated Smads (2 and 3). Antagonistic Smad 7 forms stable association with the activated TGF-beta type I receptor, blocking phosphorylation of receptor-regulated Smads. On the other hand, elevated serum concentration of TGF-beta along with resistance to its growth-inhibitory effect is commonly observed in human hepatocellular carcinoma (HCC) patients. In this study, we investigated the mechanisms of resistance to tumor-derived TGF-beta in human HCC and hepatoblastoma-derived cell lines, focusing on the roles of receptor-regulated Smads and antagonistic Smad 7. HuH-7 and HepG2 cells showed poor response to TGF-beta-mediated growth inhibition. Because neutralization of TGF-beta in the medium or blockage of signal transduction pathway by inductions of dominant negative Smad 2/3 resulted in a stimulation of cell growth, tumor-derived TGF-beta signal acts on cell growth negatively. However, Smad 7 induced by TGF-beta negatively regulated Smad 2 action and rendered most Smad 2 proteins in the cytoplasm. Taken together, these results indicate that endogenous TGF-beta-mediated induction of Smad 7 results in a higher "threshold" for the antiproliferative signals mediated by receptor-regulated Smads, and can be involved in reduced responsiveness to the cytokine in some human HCC cells.

Carcinoma, Hepatocellular↗

PubMed2000

Modulation of transforming growth factor beta function in hepatocytes and hepatic stellate cells in rat liver injury.

BACKGROUND: Transforming growth factor beta (TGF-beta) regulates hepatocyte proliferation and biosynthesis of the extracellular matrix. AIMS: This study investigated alternations in sensitivity to TGF-beta1 and binding properties for ligand in hepatocytes and hepatic stellate cells (HSC) after CCl(4) administration. METHODS: Plasma TGF-beta1 levels in rats after CCl(4) administration were determined using ELISA. Effects of TGF-beta1 were examined by DNA synthesis in hepatocytes and by measurement of fibronectin production in HSC after CCl(4) administration. Binding of (125)I TGF-beta1 was tested in these cells. RESULTS: Plasma TGF-beta1 levels were increased as early as 24 hours and were maximal by 48 hours. The antiproliferative response to TGF-beta1 decreased in hepatocytes at 48 hours and normalised at 72 hours. Fibronectin production of both normal and injured HSC was affected by TGF-beta1 treatment. Cross linked ligand/receptor complexes were detected in normal hepatocytes and HSC. However, these levels decreased specifically in hepatocytes at 48 hours and normalised by 72 hours. CONCLUSIONS: Downregulation of TGF-beta receptor occurred in hepatocytes after chemical insult and TGF-beta1 could not transduce its antiproliferative signal. Recovery of TGF-beta receptor expression causes the signal to transduce to the nucleus at 72 hours. In HSC, whenever TGF-beta1 is increased, TGF-beta1 can transduce its signal for fibronectin production via its receptor because signalling receptors are expressed constantly.

Animals↗

PubMed2000

[Animal models of cardiomyopathy].

Animal models of cardiomyopathy have been used in many studies for our understanding of the pathophysiology of this disease. Syrian hamster, BIO 14.6, one of the most widely used models of cardiomyopathy, was reported to be caused by large deletion in the exon 1 and the promoter region of the delta-sarcoglycan gene. Cardiac hypertrophy or heart failure has been induced in dogs, rabbits, rats and many other animals by various manipulations such as drugs, pressure and/or volume overload and chronic rapid pacing. Recently, transgenic or knockout mice were examined to investigate the pathogenesis and development of the disease. It is important to select appropriate models for the aim of the studies.

Animals↗

PubMed1999

High yield refolding and purification process for recombinant human interleukin-6 expressed in Escherichia coli.

Recombinant human interleukin-6 (hIL-6), a pleiotropic cytokine containing two intramolecular disulfide bonds, was expressed in Escherichia coli as an insoluble inclusion body, before being refolded and purified in high yield providing sufficient qualities for clinical use. Quantitative reconstitution of the native disulfide bonds of hIL-6 from the fully denatured E. coli extracts could be performed by glutathione-assisted oxidation in a completely denaturating condition (6M guanidinium chloride) at protein concentrations higher than 1 mg/mL, preventing aggregation of reduced hIL-6. Oxidation in 6M guanidinium chloride (GdnHCl) required remarkably low concentrations of glutathione (reduced form, 0.01 mM; oxidized form, 0.002 mM) to be added to the solubilized hIL-6 before the incubation at pH 8.5, and 22 degrees C for 16 h. After completion of refolding by rapid transfer of oxidized hIL-6 into acetate buffer by gel filtration chromatography, residual contaminants including endotoxin and E. coli proteins were efficiently removed by successive steps of chromatography. The amount of dimeric hIL-6s, thought to be purification artifacts, was decreased by optimizing the salt concentrations of the loading materials in the ion-exchange chromatography, and gradually removing organic solvents from the collected fractions of the preparative reverse-phase HPLC. These refolding and purification processes, which give an overall yield as high as 17%, seem to be appropriate for the commercial scale production of hIL-6 for therapeutic use.

Amino Acid Sequence↗

PubMed1999

Down-regulation of TGF-beta receptors in human colorectal cancer: implications for cancer development.

Many colorectal cancer cells are resistant to the anti-proliferative effects of transforming growth factor-beta (TGF-beta). TGF-beta also acts as paracrine factor from cancer cells on their mesenchymal cells. The aim of this study was to examine the expression of TGF-beta and its receptors in human colorectal cancer tissue and determine any relationship with cancer growth. In situ hybridization and Northern blot hybridization detection of TGF-beta1, type I and type II receptor mRNA and immunohistochemical staining of TGF-beta1 were performed using 11 human colorectal adenomas, 22 colorectal cancers and ten normal colorectal mucosas as control. TGF-beta receptor mRNAs were expressed mainly by normal colorectal epithelial cells and adenoma. However, mRNAs for TGF-beta receptors were only faintly, if at all, expressed in eight of 22 human colorectal cancers. In addition, intense signals of TGF-beta1 mRNA and the protein were detected in all colorectal cancers. TGF-beta receptor mRNAs and TGF-beta1 protein were also distributed in fibroblasts and endothelial cells in the interstitium. Moreover, Smad 4 protein was translocated to nucleus in primarily cultured adenoma cells, but not in cancer cells after TGF-beta stimulation. The escape of human colon cancer from TGF-beta-mediated growth inhibition by down-regulation of TGF-beta receptors as well as the effects of TGF-beta on stroma formation and angiogenesis indicate a possible role for TGF-beta in the progression of colon cancer in an intact host.

Adenoma↗

PubMed1998

Differential expression of transforming growth factor-beta and its receptors in hepatocytes and nonparenchymal cells of rat liver after CCl4 administration.

BACKGROUND/AIMS: Transforming growth factor-beta (TGF-beta) is a family of multifunctional proteins that regulate hepatocyte proliferation, and biosynthesis of the extracellular matrix. In this study we examined whether modulation of TGF-beta receptor expression contributes to the liver diseases. METHODS: The mRNA expression of TGF-beta1, TGF-beta type I receptor (TGFbetaRI), TGF-beta type II receptor (TGFbetaRII) and TGF-beta type III receptor (TGFbetaRIII) in rat livers injured by CCl4 administration was studied by Northern blotting. The mRNA expression patterns were confirmed by in situ hybridization. RESULT: The peak of TGF-beta1 mRNA expression was observed 48 h after acute intoxication with CCl4 in nonparenchymal cells. However, the levels of TGFbetaRI and TGFbetaRII mRNA expression decreased from 24 h to 48 h and from 12 h to 48 h, respectively, and returned to the normal level by 72 h. TGFbetaRII mRNA expression was depressed more and for longer than that of TGFbetaRI mRNA. Analysis in separated hepatocytes and nonparenchymal cells from the injured livers indicated that the mRNA changes occurred in hepatocytes. Nonparenchymal cells expressed TGFbetaRI and TGFbetaRII mRNAs at constant levels during liver regeneration. TGFbetaRIII mRNA, which also decreased after 12 h, was not apparent in hepatocytes but only in nonparenchymal cells. CONCLUSIONS: These observations suggest that: (i) whenever TGF-beta1 is increased in CCl4-treated livers, it may induce liver fibrogenesis via nonparenchymal cells; (ii) the mitoinhibitory effect of TGF-beta1 on hepatocytes is transiently relieved by down-regulation of TGF-beta receptors for 72 h post-damage; and (iii) the resistance to TGF-beta growth inhibition between 24 to 48 h may be predominantly due to down-regulation of the expression of TGFbetaRII.

Animals↗

PubMed1997

Skeletal muscle fiber degeneration in mdx mice induced by electrical stimulation.

We present an in vitro model in which mouse skeletal muscle fibers undergo degeneration by increasing the current strength of tetanic stimulation. To understand the mechanisms of muscle fiber necrosis in Duchenne muscular dystrophy patients, the process of fiber degeneration was compared between mdx and control mice. The process consisted of four steps, beginning with muscle fiber contraction and extending to onset of myofibril disruption. The four processes were not observed in fibers in Krebs-HEPES (-Ca2+) buffer, nor in the presence of L-type Ca2+ channel blockers. These results suggest that this degenerative phenomenon is regulated by intracellular Ca2+, which moved into fibers mainly through voltage-dependent L-type Ca2+ channels. With the exception of myofibril disruption, mdx mice also exhibited the three other steps, but at a significantly lower current strength than in the fibers in the control mice. We postulate that excess Ca2+ flux occurs in fibers, mainly through abnormal L-type Ca2+ channels, and that the excessively accumulated calcium results in premature degeneration of the fibers by tetanic contraction. This study would provide a clue to investigate and prevent the degeneration processes in Duchenne muscular dystrophy.

Animals↗

PubMed1997

Transfer of autoimmune thyroiditis and resolution of palmoplantar pustular psoriasis following allogeneic bone marrow transplantation.

We report an unusual case of a patient who was cured of one autoimmune disease (palmoplantar pustular psoriasis (PPP)) but developed another autoimmune disease (autoimmune thyroiditis) after allogeneic BMT. A 40-year-old man suffering from AML with PPP underwent allogeneic BMT from his HLA-identical sister for the treatment of AML. The patient experienced complete clearance of the cutaneous PPP despite the cessation of immunosuppressive therapy for over 2 years. However, he developed hyperthyroidism with anti-thyroglobulin antibodies 5 months after BMT, although he had showed normal thyroid functions without anti-thyroglobulin antibodies before BMT. The donor had no history of thyroid diseases and showed normal thyroid functions but was positive for anti-thyroglobulin antibodies. Thus, even when the donor is in a subclinical state, autoimmune thyroiditis may be transferred from donors to recipients by BMT.

Adoptive Transfer↗

PubMed1997

[Rubella virus].

The paper deals with a review article of nervous system disorders caused by rubella virus (RV) infection. The diseases are categorized as acute and chronic, the former consists of acute encephalitis and peripheral neuropathy, and the latter congenital rubella syndrome and progressive rubella panencephalitis. Acute rubella encephalitis occurs one case per 6,000 rubella patients either at viremia or eruption stage which is a demyelinating disease designated as secondary encephalitis. The prognosis of those diseases are not too severe, 80% of the diseases are recovered without any sequels. Congenital rubella syndrome is a congenital malformation syndrome such as cataracts, glaucoma, ventricular and atrial septal defect, mental and motor retardation, hearing difficulty by rubella infection at first trimester of pregnancy. A Japanese case of progressive rubella panencephalitis was reported in Arch Neurol in 1987 by us and died at home after physical and mental deterioration. Although reinfection of rubella virus may occur in mother having antibody to RV during pregnancy who bears possibly baby with congenital rubella syndrome eventually, the best way to decrease patients with RV infection in nervous system is to immunize all people with live RV.

Encephalitis, Viral↗

PubMed1997

[Cousins with X-linked recessive myotubular myopathy].

We describe two cousins with severe infantile form of myotubular myopathy. In Japan this disease has previously been reported in only three families. Case 1. The propositus, a 2-year-5-month-old boy, had been on a respirator since birth. He had a history of severe neonatal asphyxia and sequential hypotonia with dyspnea. Findings diagnostic of congenital myotubular myopathy, such as central nuclei and peripheral halo of muscle fibers, were demonstrated in his biopsied muscle. Case 2. A male the cousin of case 1 had congenital myopathy and died at 3 months of age due to respiratory failure. His muscle biopsy disclosed the identical findings as had been seen in case 1. These two cases were born to twin mothers, suggesting X-linked recessive inheritance. Early diagnosis and proper treatment of myotubular myopathy are important, because this condition may be erroneously-interpreted as the sequelae of neonatal asphyxia.

Child, Preschool↗

PubMed1997

[Splenic lymphoma with villous lymphocytes and complex chromosomal abnormality].

We report a 70-year-old Japanese man who had splenic lymphoma with villous lymphocytes and a complex chromosomal abnormality. No monoclonal gammopathy was present. The peripheral blood film showed lymphocytes with thin and short villi arising from one or two poles of the cells. These cells were negative for tartrate-resistant acid phosphatase stain. Immunophenotyping of peripheral blood lymphocytes showed moderate to strong expression of surface membrane IgM, IgD, IgA, and lambda as well as CD19, CD20, CD21, CD24, and HLA-DR. In addition, there was weak CD5, CD22, and CD25 expression, but no CD10, CD11c, CD23, CD38, or B-ly-7 expression. All 20 metaphases obtained from peripheral blood cells cultured for 5 days with lipopolysaccharide showed an abnormal karyotype: 47, XY, +der(3) t(3; 13) (q26; q12) inv(3) (?), t(7; 14), (q21; q11), der(13) t(3; 13) (q26; q12). Our patient followed a relatively benign clinical course and splenectomy was not performed.

Aged↗

PubMed1997

Induction of apoptosis in megakaryocytic leukemia cell lines by MX2, a morpholino anthracycline.

Leukemia with megakaryocytic involvement has a poor prognosis. MX2 is a new morpholino anthracycline that is effective against various leukemic cell lines. This study examined the antitumor activity of MX2 against human megakaryocytic cell lines, including CMK, CMK11-5, MEG-01, and UT-7, and investigated the role of apoptosis in the cytotoxicity of this drug. To quantify the extent of apoptosis induced by MX2, we used the in situ terminal deoxynucleotide transferase assay and the histone-associated DNA fragmentation assay. The cytotoxic effect of MX2 on CMK cells was reduced by various inhibitors of apoptosis. To our knowledge, this is the first report showing that apoptosis is involved in the killing of megakaryocytic cell lines by an antileukemic agent. We suggest that MX2 may be useful for the treatment of megakaryocytic leukemia.

Antibiotics, Antineoplastic↗

PubMed1996

Tumor cell autocrine motility factor is the neuroleukin/phosphohexose isomerase polypeptide.

To date, the structure of the autocrine motility factor (AMF), a tumor-secreted cytokine which stimulates cell migration in vitro and metastasis in vivo, is unknown. Here, AMF secreted by Gc-4 PF murine fibrosarcoma into a protein-free conditioned media was isolated, purified, and microsequenced. The results demonstrate that AMF is the previously cloned cytokine and enzyme designated as neuroleukin, and phosphohexose isomerase (PHI), which has been independently implicated in cell motility, and to be a cancer progression marker. PHI catalyzes isomerization of glucose 6-phosphate to fructose 6-phosphate and is specific for both sugars. Murine AMF exhibits the enzymatic properties of PHI and rabbit heart PHI-stimulated mouse fibrosarcoma cells' motility similar to those of the endogenous AMF. Specific PHI inhibitors (carbohydrate phosphates) inhibited enzymatic activity and AMF-induced cell motility.

Amino Acid Sequence↗

PubMed1996

Establishment of a myeloid leukaemia cell line (Kasumi-4) with t(9;22;11)(q34;q11;q13), inv(3)(q21q26) and the EVI1 gene activation from a patient with chronic myelogenous leukaemia in blast crisis.

A novel human leukaemia cell line (Kasumi-4) was established from the peripheral blood of a 6-year-old girl suffering from chronic myelogenous leukaemia (CML) in blast crisis. The Kasumi-4 cells had the following characteristic features: undifferentiated blasts which were positive from CD34, CD33 and CD13 surface markers, but negative for myeloperoxidase platelet peroxidase, CD36, CD41 and CD42; chromosome abnormalities of t(9;22;11) (q34;q11;q13), inv(3)(q21q26); and elevated expression of EVI1 gene which is located at chromosome band 3q26. Megakaryocytic maturation was not observed in the liquid culture following the addition of TPA, IL3, IL-6 or GM-CSF, b2-a2 type of BCR-ABL chimaeric messenger RNA was detected by RT-PCR analysis. This the first leukaemia cell line with a three-way translocation containing the the Ph chromosome and the second cell line with an inv(3)(q21q26). This cell line appears to be useful for studying the mechanisms of leukaemogenesis involving these chromosomal abnormalities and related oncogenes.

Base Sequence↗

PubMed1995

[A case of rubella encephalitis: rubella virus genome was detected in the cerebrospinal fluid by polymerase chain reaction].

We studied a 2-year-old boy who had been diagnosed as having rubella encephalitis by detection of rubella virus genome in his cerebrospinal fluid with the reverse transcription-polymerase chain reaction (PCR). PCR was considered to be very useful not only to make an early diagnosis of rubella encephalitis but also to be applied generally to that of various viral encephalitis.

Cerebrospinal Fluid↗