Biomedical subjects

M Kawamura

Publications and source records attributed to M Kawamura.

At least 307 records · Page 17Linked to original sources

PubMed1995

Angiotensin II type 1 receptor blockade inhibits the expression of immediate-early genes and fibronectin in rat injured artery.

BACKGROUND: Vascular injury activates various kinds of genes, including proto-oncogenes, growth factors, and extracellular matrix proteins. However, the significance of activation of these genes in neointimal formation is poorly understood. Angiotensin II type 1 (AT1) receptor antagonist is shown to prevent neointimal formation after vascular injury, although the mechanism is unclear. To understand the molecular mechanism of vascular thickening, we examined the effects of AT1 receptor blockade on the gene expression of proto-oncogenes, transforming growth factor-beta 1 (TGF-beta 1), and extracellular matrix proteins after vascular injury. METHODS AND RESULTS: Endothelial denudation of the left common carotid artery in Sprague-Dawley rats was performed with a Fogarty 2F balloon catheter. TCV-116 (10 mg.kg-1.d-1), a selective nonpeptide AT1 receptor antagonist, or vehicle was administered orally to rats from 1 day before to 14 days after balloon injury. Injured left and uninjured right common carotid arteries were removed from rats at 1, 6, and 24 hours and 3, 7, and 14 days after balloon injury. Tissue mRNA levels were measured with Northern blot analysis using specific cDNA probes and corrected for 18S ribosomal RNA value. Arterial mRNAs for c-fos, c-jun, jun B, jun D, and Egr-1 increased significantly at 1 hour after balloon injury and decreased rapidly. At 6 hours, ornithine decarboxylase (ODC) mRNA expression reached the maximal levels. TGF-beta 1 and fibronectin mRNA levels started to increase at 6 hours after injury and remained enhanced until 7 days after injury. On the other hand, collagen types I, III, and IV and laminin mRNA levels were not significantly increased over 7 days. Treatment with TCV-116 significantly inhibited the induction of mRNAs for c-fos, c-jun, Egr-1, ODC, and fibronectin in injured artery, whereas the increase in TGF-beta 1 gene expression after injury was not prevented by TCV-116. Immunohistological studies indicated that TCV-116 decreased not only the intimal thickening but also the amount of these extracellular matrix proteins in the intima. CONCLUSIONS: The results indicate that AT1 receptor blockade inhibits the induction of immediate-early genes, ODC, and fibronectin in rat injured artery. Thus, inhibition of intimal thickening by AT1 receptor blockade may be mediated at least in part by suppression of multiple genes related to cell growth and migration in the very early phase after vascular injury.

Angioplasty, Balloon↗

PubMed1995

Overexpression of human lipoprotein lipase increases hormone-sensitive lipase activity in adipose tissue of mice.

An elevation of lipoprotein lipase (LPL) activity in adipose tissue is considered a possible cause of obesity. However, transgenic mice that overexpress the human LPL gene showed no increase in fat deposition as compared with controls. In the present study, we investigated effects of LPL on fat accumulation. Respiratory quotients and uptake of [3H] triolein by tissues (white and brown adipose tissue, and skeletal muscles) did not differ significantly for transgenic and non-transgenic mice. The mRNA levels of hormone-sensitive lipase (HSL) and HSL activity in adipose tissue during feeding were higher in LPL transgenic mice than in controls. Results suggest that the overexpression of LPL does not induce obesity by enhancing the hydrolysis of triglycerides in adipose tissue.

Adipose Tissue↗

PubMed1995

Rev-dependency of expression of human immunodeficiency virus type 1 gag and env genes.

Structural gene expression of human immunodeficiency virus type 1 (HIV-1) requires a viral regulatory protein, Rev transactivator. We investigated Rev-dependency of HIV-1 gene expression by various reporter systems. Expression of unspliced and single-spliced viral mRNAs was demonstrated to be differentially dependent on the Rev function. This difference of Rev-dependency was found not to be determined by cis-elements in gag, pol, and env coding sequences reported so far, and was lost when the reporter constructs containing minimum elements for Rev-responsiveness such as splice signals and rev responsive element were used for experiments. These findings indicated that the fundamental structure of HIV-1 mRNA was critical for the differential regulation of gene expression by Rev transactivator.

Animals↗

PubMed1995

Mutations of the p53 and ras genes in childhood t(1;19)-acute lymphoblastic leukemia.

We have investigated the alterations of p53 and ras genes including H-, K-, and N-ras genes in 22 acute lymphoblastic leukemia (ALL) cases and five cell lines carrying t(1;19) by use of polymerase chain reaction (PCR)-single-strand conformation polymorphism (SSCP) analysis and direct sequencing. The mutations of the p53 gene were found in 2 of 20 t(1;19)-ALL cases at diagnosis (10%), all of 4 cases at relapse (100%), and 4 of the 5 cell lines (80%). Four of the five patients who died had missense mutations at codons 49, 177, 179, and 248. In cases examined sequentially, one had the same point mutation at codon 179 at both diagnosis and relapse, and another had the same p53 gene mutation at codon 240 both in leukemic cells at relapse and in a cell line derived at that time. The other case had no mutation at diagnosis but had the mutation at codon 177 at relapse and cell lines derived from blast cells at diagnosis, suggesting that a small number of leukemic cells with the p53 gene mutation at diagnosis might have escaped PCR-SSCP analysis. In cell lines, SCMC-L9 had three point mutations in the p53 gene at codons 175, 248, and 358, whereas SCMC-L10 had frame shift at codons 209-211. One case had a rare polymorphism at codon 11. We found only one mutation of the N-ras gene that was a 2-bp substitution of GGT(Gly) to GTC(Val) at codon 13 among 22 t(1;19)-ALL cases and five cell lines. This case showed no mutation of the p53 gene and has had a good course. These results suggest that in t(1;19)-ALL, mutations of the p53 and ras genes are infrequent at diagnosis and that p53 gene alterations may be associated with relapse phase or progression of t(1;19)-ALL.

Adolescent↗

PubMed1995

Activation of JAK3, but not JAK1, is critical to interleukin-4 (IL4) stimulated proliferation and requires a membrane-proximal region of IL4 receptor alpha.

The tyrosine kinases JAK1 and JAK3 have been shown to undergo tyrosine phosphorylation in response to interleukin-2 (IL), IL4, IL7, and IL9, cytokines which share the common IL2 receptor gamma-chain (IL2R gamma), and evidence has been found for a preferential coupling of JAK3 to IL2R gamma and JAK1 to IL2R beta. Here we show, using human premyeloid TF-1 cells, that IL4 stimulates JAK3 to a larger extent than JAK1, based upon three different evaluation criteria. These include a more vigorous tyrosine phosphorylation of JAK3 as measured by anti-phosphotyrosine immunoblotting, a more marked activation of JAK3 as determined by in vitro tyrosine kinase assays and a more manifest presence of JAK3 in activated IL4-receptor complexes. These observations suggest that IL4 receptor signal transduction does not depend on equimolar heterodimerization of JAK1 and JAK3 following IL4-induced heterodimerization of IL4R alpha and IL2R gamma. Indeed, when human IL4R alpha was stably expressed in mouse BA/F3 cells, robust IL4-induced proliferation and JAK3 activation occurred without detectable involvement of JAK1, JAK2, or TYK2. The present study suggests that JAK1 plays a subordinate role in IL4 receptor signaling, and that in certain cells exclusive JAK3 activation may mediate IL4-induced cell growth. Moreover, mutational analysis of human IL4R alpha showed that a membrane-proximal cytoplasmic region was critical for JAK3 activation, while the I4R motif was not, which is compatible with a role of JAK3 upstream of the recruitment of the insulin receptor substrate-1/4PS signaling proteins by IL4 receptors.

Amino Acid Sequence↗

PubMed1995

Effects of thromboxane A2 synthase inhibitors (CV-4151 and ozagrel), aspirin, and ticlopidine on the thrombosis caused by endothelial cell injury.

The antiplatelet and antithrombotic effects of CV-4151 (isbogrel), a potent selective thromboxane A2 (TXA2) synthase inhibitor, were compared with those of ozagrel (OKY-046), aspirin, and ticlopidine in rats. Two hours after oral administration, CV-4151, ozagrel and aspirin inhibited blood TXA2 generation with ID50 values of 0.04, 0.3 and 6.4 mg/kg, respectively. These values were similar to the oral ID50 values of CV-4151 (0.06 mg/kg), ozagrel (0.92 mg/kg) and aspirin (7.0 mg/kg) for arachidonic acid (AA)-induced platelet aggregation ex vivo. Two hours after p.o. administration, CV-4151 and ozagrel inhibited femoral vein platelet-rich thrombosis caused by endothelial injury with ID50 values of 2.46 and 13.7 mg/kg, respectively. However, aspirin (100 mg/kg, p.o.) only slightly inhibited the thrombosis. Ticlopidine (300 mg/kg, p.o.) slightly but significantly inhibited AA-induced and ADP-induced platelet aggregation, however, it potently inhibited the thrombosis. CV-4151 and ozagrel given by i.v. injection showed therapeutic effects on the thrombosis with ED50 values of 0.026 and 0.066 mg/kg, respectively. These values were similar to the i.v. ED50 values of CV-4151 (0.0056 mg/kg) and ozagrel (0.042 mg/kg) for blood TXA2 generation. However, aspirin (30 mg/kg, i.v.) only moderately reduced the thrombosis. CV-4151 (> 0.3 mg/kg, p.o.), ozagrel (> 3 mg/kg, p.o.) and ticlopidine (300 mg/kg, p.o.) all significantly prolonged tail bleeding time. Aspirin (100 mg/kg, p.o.) tended to prolong the bleeding time. The antiplatelet and antithrombotic effects of CV-4151 are more potent than those of ozagrel, aspirin and ticlopidine in rats. CV-4151 may therefore be a useful drug for the treatment of thrombotic diseases.

Animals↗

PubMed1995

Evaluation of plasma 11-dehydro-thromboxane B2 as an indicator for thromboxane A2 synthesis in vivo in laboratory animals.

Since thromboxane (TX) B2 is not a reliable indicator of TXA2 generation in vivo, because of artifactual TXA2 generation during blood collection, we tested the feasibility of replacing TXB2 with 11-dehydro (dh)-TXB2 as the indicator. Plasma levels of TXB2 and 11-dh-TXB2 were measured after i.v. administration of TXB2 to rabbits, guinea pigs, rats, dogs and a monkey, and after i.v. infusion of collagen in rabbits. In the rabbits and dogs, 2,3-dinor-TXB2 levels were also measured. After intravenous injection of TXB2 (10 micrograms/kg) in rabbits, the ratio of the area under the curve (AUC) of 11-dh-TXB2 to that of TXB2 (1.94) was far higher than the AUC ratio between 2,3-dinor-TXB2 and TXB2 (0.42). When endogenous TXA2 was generated by infusion of collagen (2 mg/kg/5 min), the plasma level of 11-dh-TXB2 was significantly increased, and had a longer half-life than TXB2. In the guinea pigs, rats and monkey, the peak plasma levels of 11-dh-TXB2 were significantly increased after injection of TXB2 (10 micrograms/kg, i.v.), whereas the AUC ratios of 11-dh-TXB2/TXB2 were less than one fourth of that in rabbits. No significant increase in 11-dh-TXB2 was observed after TXB2 injection (10 micrograms/kg) in dogs, but the 2,3-dinor-TXB2 level rose significantly, its AUC ratio to TXB2 being 0.29, comparable with that in rabbits. The order of the 11-dh-TXB2/TXB2 AUC ratios was: rabbits > guinea pigs > monkey > rats >> dogs.(ABSTRACT TRUNCATED AT 250 WORDS)

Animals↗

PubMed1995

Role of macrophage colony-stimulating factor in the initial process of atherosclerosis.

The early atherosclerotic lesion is characterized by the presence of macrophage-derived foam cells. Macrophage colony-stimulating factor (M-CSF) specifically stimulates the functions of the monocyte-macrophages. To elucidate the role of M-CSF in the atherogenic process in vitro and in vivo, we studied the effects of M-CSF on enzyme activities of acidic cholesteryl ester (CE) hydrolase, neutral CE hydrolase, and acyl-coenzyme A:cholesterol acyltransferase (ACAT), and 300 micrograms of M-CSF was intravenously injected into WHHL rabbits aged 2.5 months for 8.5 months. M-CSF (100 ng/ml) enhanced acidic and neutral CE hydrolase, and ACAT activities by 3.2-fold, 4-fold, and 2.3-fold, respectively, in the presence of acetyl LDL, and M-CSF increased ratios of both acidic and neutral CE hydrolase activities to ACAT activity. After M-CSF injection into WHHL rabbits, we found very retarded progression of atherosclerosis. The accumulation of cholesterol ester was remarkably decreased in the aortae of M-CSF-treated animals (0.60 +/- 0.32 mg/g tissue), as compared to those of controls (4.21 +/- 0.65 mg/g tissue). The results suggest that M-CSF prevents the progression of atherosclerosis in WHHL rabbits by increasing net hydrolysis of cholesteryl ester in macrophages.

Animals↗

PubMed1995

Activation of JAK3, but not JAK1, is critical for IL-2-induced proliferation and STAT5 recruitment by a COOH-terminal region of the IL-2 receptor beta-chain.

A number of cytokines and growth factors use the JAK-STAT pathway to signal from the cell membrane to the nucleus. While homodimerizing cytokine receptors may transmit signal via a single form of JAK (i.e. growth hormone receptors), several multicomponent cytokine receptors have been shown to require simultaneous activation of pairs of different JAK kinases (i.e. interferon receptors). Recent evidence for a preferential coupling of JAK3 to interleukin-2 receptor-gamma (IL-2R gamma) and JAK1 to IL-2R beta supports the concept of heterotrans-activation of JAK1 and JAK3 caused by IL-2-induced heterodimerization of their receptor partners. The present study verified the ability of IL-2 to cause tyrosine phosphorylation and activation of JAK1 and JAK3, but demonstrated that IL-2 stimulated JAK3 to a significantly larger extent than JAK1 in human T lymphocytes and the YT cell line. This conclusion was based upon several independent criteria, including more vigorous tyrosine phosphorylation of JAK3, more marked enzymatic activation of JAK3 as well as higher abundance of JAK3 in activated IL-2 receptor complexes. Furthermore, when human IL-2R beta was stably expressed in murine BA/F3 cells, robust IL-2-induced proliferation and JAK3 activation occurred without detectable involvement of either JAK1, JAK2 or TYK2. We therefore propose that IL-2 receptor signal transduction does not depend on equimolar heterodimerization of JAK1 and JAK3 following IL-2-induced heterodimerization of IL-2R beta and IL-2R gamma. Nonetheless, a membrane-proximal region of human IL-2R beta (Asn240-Leu335) was critical for JAK3 activation, and the amount of JAK3 present in activated IL-2 receptor complexes increased with time, suggesting that stabilization of JAK3 binding to the receptor complex relies on both IL-2R beta and IL-2R gamma. Moreover, STAT5 was found to be the predominant STAT transcription factor used by IL-2 in human T cells, and specifically required a COOH-terminal region of IL-2R beta (Ser386-Val525), while STAT5 recruitment was not correlated to activation of IL-2R gamma or JAK3.

Amino Acid Sequence↗

PubMed1995

The expression of Na+/K(+)-ATPase beta-subunit cRNA injected into Xenopus oocytes is affected by coinjection with alpha-subunit cRNA.

The cRNA for Torpedo californica Na+/K(+)-ATPase beta-subunit (cRNA beta) was injected into Xenopus oocytes alone or with the cRNA for the Na+/K(+)-ATPase alpha-subunit (cRNA alpha). When cRNA beta was injected alone, the amount of the beta-subunit that accumulated in oocytes increased with increasing amounts of injected cRNA beta. When cRNA beta and cRNA alpha were injected simultaneously, less beta-subunit accumulated than when cRNA beta was injected alone, whereas the Na+/K(+)-ATPase activity increased markedly. The decrease in the accumulation of the beta-subunit was dose-dependent upon the cRNA alpha. The mutant beta-subunit unable to assemble with the alpha-subunit accumulated in oocytes independently of cRNA alpha, suggesting that post-translational control mechanisms may serve to reduce the accumulation of the beta-subunit.

Animals↗

PubMed1995

Biochemical studies of glycosaminoglycans in nanophthalmic sclera.

BACKGROUND: Since Brockhurst reported the connection between uveal effusion in nanophthalmic eyes and their scleral alterations and treated them with vortex vein decompression or sclerectomy, many observers have found abnormal accumulation of glycosaminoglycans (GAGs) in nanophthalmic sclera. These GAG abnormalities were thought to effect the collagen changes, though it was not clear which GAGs were changed. METHODS: GAGs were isolated and their contents were determined in scleral specimens from three nanophthalmic patients and five age-matched controls, using electrophoresis and the cetylpyridinium method. RESULTS: Hyaluronic acid, dermatan sulfate and chondroitin sulfate were the major GAGs in both nanophthalmic and control samples. Nanophthalmic sclera showed 2.4-fold, 10-fold and 5.5-fold increases in hyaluronic acid, dermatan sulfate and chondroitin sulfate, respectively, compared with the controls. CONCLUSION: The results suggest that increased levels of GAGs, particularly of dermatan sulfate and chondroitin sulfate may contribute to the abnormalities of collagen fibrillogenesis and be closely involved with the pathogenesis of nanophthalmos.

Adult↗

PubMed1995

Experimental tracheal replacement using the esophagus and an expandable metallic stent.

An experimental study was conducted to investigate whether a segment of autogenous esophagus with its lumen supported by an expandable metallic stent (EMS) could be successfully used as a tracheal substitute. Seven rings of the cervical trachea were circumferentially removed and reconstructed by interposing a pedicled segment of the esophagus with an EMS in six mongrel dogs. The interposed esophagus was observed endoscopically at various stages after the operation. By 1 month, the EMS was found to be buried under the esophageal mucosa, and the lumen was patent. The dogs died 5, 17, 61, 92, 210, and 478 days after the operation, but the cause of death could not be determined by postmortem examination and no respiratory tract complications were detected. The results of this study indicated that a segment of the esophagus with its lumen supported by an EMS could work as a reliable tracheal substitute, though its practical use is not clinically feasible. Nevertheless, we conclude that some autogenous material other than the esophagus with its lumen supported by an EMS could provide a feasible method for tracheal replacement.

Anastomosis, Surgical↗

PubMed1995

Characterization of Japanese families with early-onset type 2 (non-insulin dependent) diabetes mellitus and screening for mutations in the glucokinase and mitochondrial tRNA(Leu(UUR)) genes.

Genetic linkage studies of families with early-onset type 2 diabetes have facilitated the identification of diabetes-susceptibility genes. In order to assess the feasibility of using linkage approaches to identify genes responsible for the development of type 2 diabetes in Japanese subjects, we examined our clinical records for multigenerational families suitable for genetic studies. We identified 16 families in which at least one subject was diagnosed with type 2 diabetes before 25 years of age. Seven of these families had a pattern of inheritance consistent with a diagnosis of maturity-onset diabetes of the young (MODY) and nine families showed a complex pattern of inheritance of type 2 diabetes with transmission of diabetes-susceptibility genes from both parents. The glucokinase and mitochondrial tRNA(Leu(UUR)) genes were screened for mutations in at least one affected subject from each family in order to assess the contribution of mutations in these genes to the development of the diabetes. No mutations were found, which suggests that the diabetes in these families resulted from mutations in other genes.

Adolescent↗

PubMed1995

Functionality of chimeric Rev proteins of HIV/SIV.

Studies on functional compatibility of various Rev proteins derived from all known human and simian immunodeficiency virus subgroups have shown that this essential gene product is not always exchangeable among the viruses. In an attempt to map the region of Rev proteins responsible for the observed nonreciprocal complementation, hybrid genomic Rev expression vectors were constructed by exchanging the first and second exons of rev genes, and were examined for their abilities to activate reporter clones by transfection. With one exception, the second coding exon of rev gene determined the functional specificity of Rev proteins.

Animals↗

PubMed1995

Functional analysis of human spuma retrovirus genome.

Human spuma retrovirus (HSRV) belongs to retroviruses that possess a complex genome organization. HSRV carries at least three extra genes in the region between env and the 3' long terminal repeat, which are not found in simple retroviruses. Via alternative splicing, these HSRV genes can encode several proteins. To genetically study the requirements of these viral proteins for viral replication in tissue cultures, a number of mutant viruses were constructed from an infectious molecular clone of HSRV. All mutants grew normally in the cell lines tested, except for those lacking transcriptional transactivator activity. By reporter-based transient assay systems, no Rev/Rex equivalent was detected in the HSRV proteins.

Alternative Splicing↗

PubMed1995

Use of acetylcholine (Ach) for spreading metaphase chromosomes and application to the cytogenetic analysis of human stomach cancers.

Cytogenetic studies of biopsy specimens endoscopically obtained from gastric cancers were performed in our laboratory. The necessity for well-spread chromosomes for analysis has resulted in the development of a new technique, in which culture medium containing acetylcholine (Ach) is used; with this new technique, the number of metaphases of analyzable karyotypes was significantly increased (P < 0.01 compared with a previous method in which Ach was not used). The mean ratio of metaphase numbers of analyzable karyotypes in four cases in which Ach was used was 38.1 +/- 8.1%, a value more than four times the number in the seven cases in which Ach was not used. It is possible that Ach may decrease the viscosity of the cytoplasm in gastric cancer cells by disrupting microfilaments.

Acetylcholine↗

PubMed1995

Mitral valve replacement via right thoracotomy after coronary arterial grafting.

Mitral valve replacement was performed through a right thoracotomy using femorofemoral bypass under profound systemic hypothermia in a 62-year-old man who had undergone coronary artery bypass grafting using both internal thoracic arteries. The right thoracotomy approach minimizes the risk of injury to the arterial grafts, and deep hypothermia obviates the need to interrupt the grafts to administer cardioplegia. This technique provides excellent exposure of the mitral valve while minimizing the operative risk.

Bioprosthesis↗

PubMed1995

Adrenomedullin increases cyclic AMP more potently than CGRP and amylin in rat renal tubular basolateral membranes.

In rat renal tubular basolateral membranes, the potency to increase cAMP of adrenomedullin (AM), a novel vasorelaxant peptide originally isolated from human pheochromocytoma, was compared with those of calcitonin gene-related peptide (CGRP) and amylin. Although all three peptides raised cAMP in a time- and concentration-dependent manner with a 4-fold increase at 10(-6)-10(-5) M, the EC50 value (10(-9) M) of AM was 100-fold smaller than those of CGRP and amylin. CGRP[8-37], an antagonist for CGRP receptors, attenuated cAMP elevation induced by these peptides with the essentially similar concentration-inhibition curves. These results suggest that the receptors for AM, CGRP and amylin share a common structural homology, and that the receptors sensitive to AM are preferentially expressed in renal tubular basolateral membranes.

Adrenomedullin↗