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Biomedical subjects

K Ohashi

Publications and source records attributed to K Ohashi.

At least 235 records · Page 13Linked to original sources
PubMed1998

Effect of ecadotril, a neutral endopeptidase inhibitor, on myocardial hypertrophy in the rat aortic insufficiency model.

Cardiac hypertrophy develops to compensate for hemodynamic overload of the myocardium. However, cardiac hypertrophy itself poses a serious risk to patients with heart failure. Whether natriuretic peptides enhanced by ecadotril, a neutral endopeptidase inhibitor, suppress the increase of left ventricular mass in the rat aortic insufficiency model was investigated. Ecadotril suppressed the increase of the left ventricular mass without affecting blood pressure (710.9 +/- 15.6 mg in the group treated with ecadotril and 865.0 +/- 27.3 mg in the control group, P < 0.01). Although the increase of atrial natriuretic peptide in the left ventricle was trivial and did not reach statistical significance (406.5 +/- 62.2 pg/mg in the ecadotril-treated group versus 269.8 +/- 35.7 pg/mg in the control group), urinary cGMP excretion was greater in the group given ecadotril than in the control group (10.6 +/- 2.5 pmol/mL and 1.7 +/- 0.6 pmol/mL, respectively, P < 0.01). Plasma angiotensin II concentration also decreased in the group treated with ecadotril compared with the control group (116.6 +/- 25.4 pg/mL versus 358.7 +/- 98.7 pg/mL, P < 0.05). In conclusion, ecadotril suppressed the increase of left ventricular mass in the overloaded heart. In ecadotril-treated rats, cGMP synthesis was augmented and angiotensin II concentration was reduced.

Angiotensin II↗
PubMed1998

[Portal hypertensive gastropathy and colopathy].

Gastrointestinal bleeding in patients with portal hypertension is usually secondary to esophageal varices, but massive bleeding from gastric mucosal lesions and colonic mucosal lesions including colorectal varices, have been variably described. These lesions are called portal hypertensive gastropathy and colopathy. The incidence and profile of portal hypertensive gastropathy (PHG) has been frequently reported during the last decade, and many studies showed that development of PHG is influenced by coexisting esophageal varices, absence of major portal systemic shunts, severity of liver disease and sclerotherapy and is directly correlated with portal venous pressure. Although hyperdynamic congestion seems to be the underlying mechanisms for the development of PHG, results of gastric mucosal blood flow in patients with PHG is controversial. The treatment can be currently recommended to prevent bleeding, is oral administration of propranolol which decreased portal venous pressure. The clinical feature and profile of portal hypertensive colopathy is classified two groups, which are named colorectal varices and colonic mucosal lesions including vascular spider, dilated fine branching vessels. Although colorectal varices are usually seen at rectum and sigmoid colon, colonic mucosal lesions are seen all part of colon. Significant relationship between colorectal varices and liver disease has been reported and colorectal varices is highly appeared in patients with extrahepatic portal obstruction. Such patients are revealed arteriovenous communications at angiogram. In general, colonic resection or transanal ligation should be the first option for treatment of bleeding colonic varices and colonic mucosal lesions. Transendoscopic sclerotherapy may be an alternate choice.

Colonic Diseases↗
PubMed1997

Mouse LIM-kinase 2 gene: cDNA cloning, genomic organization, and tissue-specific expression of two alternatively initiated transcripts.

LIM-kinase 1 and LIM-kinase 2 (LIMK1 and LIMK2) are members of a novel protein kinase subfamily containing LIM motifs at the N-terminus. There are two isoforms of Limk2 transcripts coding proteins with distinct N-terminal structures: LIMK2a, containing two LIM motifs, and LIMK2b, with one and one-half LIM motifs. Here we report the cDNA and genomic structures of mouse LIMK2. The deduced 638-aminoacid sequence of mouse LIMK2a shows 98% identity with that of rat LIMK2a. The mouse Limk2a gene consists of at least 16 exons and spans more than 50 kb. Exon/intron boundaries of the mouse Limk2a gene are exactly conserved with those of the mouse Limk1 gene. An additional exon encoding the Limk2b-specific 5'-terminal sequence was found to be located between exons 2 and 3, suggesting that Limk2a and 2b mRNAs are transcribed from a single Limk2 gene by an alternative usage of exons near the 5' end of the gene. Limk2a and Limk2b transcripts were expressed at different ratios in a variety of mouse tissues.

Alternative Splicing↗
PubMed1997

Cell adhesion to phosphatidylserine mediated by a product of growth arrest-specific gene 6.

Gas6, a product of a growth arrest-specific gene 6, potentiates proliferation of vascular smooth muscle cells and prevents cell death of vascular smooth muscle cells. It has been also demonstrated that Gas6 is a ligand of receptor tyrosine kinases Axl, Sky, and Mer. Gas6 contains gamma-carboxyglutamic acid residues, which are found in some blood coagulation factors and mediate the interaction of the coagulation factors with negatively charged phospholipid. In this study, we clarified that Gas6 specifically bound to phosphatidylserine and the binding was dependent on Ca2+ and gamma-carboxyglutamic acid residues. Furthermore, we found that U937 cells, which express Gas6 receptor on their surfaces, adhered to phosphatidylserine-coated enzyme-linked immunosorbent assay (ELISA) plate only in the presence of Gas6 and Ca2+. U937 cells also bound to ELISA plate coated with phosphatidylinositol, but the binding was independent of Gas6 and Ca2+. On the other hand, U937 cells did not adhere to phosphatidylcholine- or phosphatidylethanolamine-coated ELISA plate even in the presence of Gas6 and Ca2+. These findings suggest that Gas6 may play a role in recognition of cells exposing phosphatidylserine on their surfaces by phagocytic cells, which is supposed to be one of the mechanisms for clearing dying cells.

Animals↗
PubMed1997

Change in the mode of gene expression of the hypopharyngeal gland cells with an age-dependent role change of the worker honeybee Apis mellifera L.

Major proteins synthesized in the hypopharyngeal gland of the worker honeybee change from bee-milk proteins to alpha-glucosidase in accordance with the age-dependent role change of the worker bee. Previously, we showed that the gene for alpha-glucosidase is expressed specifically in the forager-bee gland [Ohashi, K., Sawata, M., Takeuchi, H., Natori, S. & Kubo, T. (1996) Biochem. Biophys. Res. Commun. 221, 380-385]. Here, we describe the isolation and analysis of cDNAs for two bee-milk 56-kDa and 64-kDa proteins. The 56-kDa protein was a glycoprotein which shared 63.2% and 56.9% amino acid sequence identities with proteins encoded by cDNA for royal-jelly-related protein 57-1 (pRJP57-1) and pRJP57-2. The 64-kDa protein cDNA was identical to pRJP57-1. Thus, these bee-milk proteins seem to form a structurally related protein family. The gene for the 64-kDa protein/RJP57-1 was expressed specifically in the nurse-bee gland, whereas that for the 56-kDa protein was expressed in both the nurse-bee and forager-bee glands. mRNAs for the 56-kDa and 64-kDa proteins were detected by in situ hybridization in a whole acinus of the nurse-bee gland, whereas mRNAs for the 56-kDa protein and alpha-glucosidase were detected in that of the forager-bee gland. Therefore, the individual secretory cells of the acinus of the hypopharyngeal gland were shown to express these genes differently with the age-dependent role change of the worker bee.

Aging↗
PubMed1997

Decrease in the amount of focal adhesion kinase (p125(FAK)) in interleukin-1beta-stimulated human umbilical vein endothelial cells by binding of human monocytic cell lines.

Monocytes in the blood circulation migrate across endothelial cell monolayers lining the blood vessels and infiltrate into the underlying tissues in inflammation. However, little is known about the mechanisms by which leukocytes migrate across the endothelial barrier after binding and what molecules participate in the process. Addition of the human monocytic cell line THP-1 to interleukin-1beta (IL-1beta)-stimulated human umbilical vein endothelial cells (HUVEC) induced a decrease in the amount of focal adhesion kinase (p125(FAK)) protein, a tyrosine kinase localized at focal contacts and essential for cell attachment to the extracellular matrix, whereas little change was observed in the amount of other molecules associated with cell adhesion such as vascular cell adhesion molecule-1, alpha-catenin, and talin. A maximum decrease in the amount of p125(FAK) was observed 15-30 min after addition of THP-1 cells to HUVEC, after which the level of p125(FAK) gradually recovered. A reduction in the density of actin stress fibers in IL-1beta-activated HUVEC was observed in parallel with the decrease in p125(FAK). The p125(FAK) decrease was partially inhibited by preventing THP-1 binding to HUVEC using a mixture of antibodies to adhesion molecules. We suggest that the decrease in p125(FAK) triggered by binding of monocytes in inflammation facilitates the transendothelial migration of the monocytes by altering the adhesiveness of endothelial cells to the extracellular matrix.

Antibodies, Monoclonal↗
PubMed1997

Effects of apo E deficiency on plasma lipid levels in mice lacking APOBEC-1.

Apolipoprotein (apo) B100 mRNA undergoes site specific C to U editing, generating a stop-translation codon of apo B48 in the small intestine. This reaction is catalyzed in an editosome which contains APOBEC-1, a catalytic subunit. To clarify the functional significance of the apo B mRNA editing in lipoprotein metabolism, we have generated APOBEC-1 knockout mice and double knockout mice which are deficient in both APOBEC-1 and apo E. The apo B mRNA editing activity was markedly reduced and complete elimination of apo B48 from the plasma was observed in APOBEC-1(-/-) mice. Plasma triglyceride levels significantly increased in the double knockout mice (APOBEC-1(-/-);apo E(-/-)) as compared to apo E(-/-) mice. These results suggest that APOBEC-1(-/-) mice are a valuable model for experiments designed to understand a role of apo B mRNA editing.

APOBEC-1 Deaminase↗
PubMed1997

Bcl-2 protein inhibits oxysterol-induced apoptosis through suppressing CPP32-mediated pathway.

Oxysterols are presumed to mediate cytotoxicity of oxidized LDL in atherosclerotic lesions. To elucidate its molecular mechanism, we established murine macrophage-like P388-D1 cells which over-express Bcl-2 protein by retrovirus-mediated gene transfer. Oxysterols (7-ketocholesterol, 25-hydroxycholesterol) induced nuclear condensation and oligonucleosomal DNA fragmentation, which were partially inhibited by Bcl-2 over-expression. Though CPP32 inhibitor suppressed the cell death in control cells, it showed no additive protection in the cells over-expressing Bcl-2. These findings indicate that oxysterols induce apoptosis via Bcl-2-inhibitable and -uninhibitable pathways, and the former depends on CPP32 activation.

Animals↗
PubMed1997

Roles of gamma-carboxylation and a sex hormone-binding globulin-like domain in receptor-binding and in biological activities of Gas6.

Gas6 is a ligand for an Axl/Sky receptor tyrosine kinase subfamily and has a structure composed of a Gla domain, four EGF-like domains and a C-terminal sex hormone-binding globulin (SHBG)-like domain. When examining the role of each domain in receptor-binding and biological activities of Gas6, we found that receptor-binding and mitogenic activities were markedly reduced by inhibiting gamma-carboxylation of the Gla domain, while a Gas6 mutant composed of only an SHBG-like domain retained both of these activities. Thus, the SHBG-like domain is apparently an entity indispensable for Gas6 activities, and gamma-carboxylation of the Gla domain has a regulatory role in retaining the activity of native Gas6.

3T3 Cells↗
PubMed1997

Involvement of 8-hydroxyguanine formation in the initiation of rat liver carcinogenesis by low dose levels of N-nitrosodiethylamine.

The question of whether 8-hydroxyguanine (8-OHG) formation is involved in initiation by low dose levels of N-nitrosodiethylamine (DEN) was addressed using a rat liver model. Male Fischer 344 rats, 6 weeks of age, were administered single i.p. doses of DEN between 0.001 and 100 mg/kg body weight. The 8-OHG levels in liver DNA were measured within 72 h thereafter in randomly selected rats. The remaining rats were given either no further treatment, partial hepatectomy (PH) at hour 4, or PH with i.p. administration of 500 mg/kg body weight of colchicine on days 1 and 3. A selection procedure was performed between weeks 2 and 4, and the initiating activity of DEN was assessed in terms of development of gamma-glutamyltransferase-positive foci at week 5. The 8-OHG levels in the liver DNA were significantly elevated between hours 6 and 72 in a manner dependent on the DEN dose. Dose-dependent induction of foci was similarly noted with doses of 1-100 and 0.001-100 mg/kg body weight in the non-PH and the PH rats, respectively. The sizes of the foci were also significantly increased in a manner dependent on the DEN doses of 1-100 and 0.001-100 mg/kg body weight in the non-colchicine-treated and the colchicine-treated rats, respectively. Statistically, linear trends of 8-OHG formation due to DEN were different at 0.001-0.1 and 1-100 mg/kg body weight, but the total adducts formed within 72 h of the administration proved to be closely related to the development of foci at the termination. These results indicate that 8-OHG formation in the liver DNA may be involved in DEN initiation of hepatocarcinogenesis even at low dose levels, and that single i.p. doses of 0.001-0.1 and 1-100 mg/kg body weight might exert different effects.

2-Acetylaminofluorene↗
PubMed1997

Proliferative activity and p53 protein accumulation correlate with early invasive trend, and apoptosis correlates with differentiation grade in oesophageal squamous cell carcinomas.

Using oesophageal squamous cell carcinoma samples of both intramucosal and advanced types, proliferative activity (Ki-67 labelling index), p53 protein accumulation and apoptosis (in situ DNA nick end labelling) were assessed, and the relation of these values to progression or differentiation grade of tumours was analysed. In terms of proliferative activity and the proportion of positive cases with p53 accumulation, a statistically significant difference was demonstrated between intraepithelial carcinomas and intramucosal carcinomas with stromal invasion (17.2% vs 31.7% for the Ki-67 labelling index, and 23.5% vs 67.4% for the proportion of positive cases of p53 accumulation). Values for the latter were almost comparable to those of advanced carcinomas. Immunohistologically, Ki-67 positive, proliferating cells were distributed preferentially in the peripheral fronts of invading nests. Apoptotic cells were observed in the inner areas of the invading nests of the intramucosal carcinomas with stromal invasion and in more advanced lesions, but were rarely observed in the normal epithelium or intraepithelial carcinomas. Apoptotic cells were seen mainly around areas of keratinization, and the apoptotic cell index was higher in well and moderately differentiated types of advanced carcinomas than in the poorly differentiated type (2.59% vs 1.09%). An increase in proliferative activity and an accumulation of p53 protein are associated with the onset of early carcinomatous invasion, while apoptosis is closely linked with the differentiation grade of carcinoma cells.

Antibodies, Monoclonal↗
PubMed1997

Transthoracic transdiaphragmatic approach for hepatectomy of Couinaud's segments VII and VIII.

For hepatectomy of Couinaud's segment VII or VIII, severe compression and mobilization of the liver is required to establish the operative field via the usual transabdominal approach. Compression of the cirrhotic liver impairs hepatic and systemic blood circulation, which may cause liver dysfunction. We adopted a transthoracic transdiaphragmatic approach for hepatectomy of segment VII or VIII in cirrhotic patients to establish a good operative field without compressing the liver. The aim of this study was to evaluate the benefits of this approach. Forty-four patients with hepatocellular carcinoma (HCC) complicating liver cirrhosis who underwent limited hepatectomy of Couinaud's segment VII or VIII were studied. The patients were randomized to two groups preoperatively: group I (n = 22), transabdominal approach; group II (n = 22), transthoracic transdiaphragmatic approach. There were no differences in preoperative liver function tests, hepatic functional reserve, or extent of tumor between the two groups. The operative time in group II was significantly shorter than that in group I (243 +/- 50 versus 313 +/- 80 minutes;p < 0.01). Operative blood loss in group II was also significantly smaller than that in group I (1190 +/- 1098 versus 2679 +/- 2267 g;p < 0.01). Serum lactate dehydrogenase levels on postoperative day 1 in group II were significantly lower than those in group I (587 +/- 154 versus 791 +/- 383 IU/L;p < 0.05). Major postoperative complications were significantly fewer in group II. It was concluded that the transthoracic transdiaphragmatic approach is a useful method for hepatectomy of segments VII and VIII in cirrhotic patients.

Chi-Square Distribution↗
PubMed1997

Sympathetic nervous responses during cytokine-induced fever in conscious rabbits.

Sympathetic responses during fever induced by two representative endogenous pyrogens, interleukin-1 beta (IL-1 beta) and tumor necrosis factor alpha (TNF alpha), and their effective inducer, lipopolysaccharide (LPS), were investigated in conscious rabbits. Rectal temperature, ear skin temperature as an index for the ear skin sympathetic nerve activity (ESNA), renal sympathetic nerve activity (RSNA), mean arterial pressure (MAP) and heart rate (HR) were recorded during fever induced by intravenous injection of these pyrogens. IL-1 beta (100 ng/kg) elicited a fever accompanied by a transient activation of ESNA and long-lasting increases in RSNA, MAP and HR. Subcutaneous indomethacin (20 mg/kg) significantly attenuated all the responses induced by IL-1 beta. TNF alpha (10 micrograms/kg) also elicited fever with increases in ESNA, RSNA and HR, while MAP was not affected. All the TNF-induced responses were totally blocked by indomethacin. LPS at two doses of 500 ng/kg and 1 microgram/kg elicited fever and increased ESNA, RSNA and HR. Only the larger dose induced hypotension. The present results show in conscious rabbits exposed to thermoneutral environment that these pyrogens activate sympathetic efferents in regionally differentiated time courses. The present results also suggest that arachidonate metabolites are involved not only in the thermoregulatory vasoconstrictor response in the ear and the body temperature increase but also in simultaneously evoked renal sympathetic and haemodynamic adjustments in fever.

Animals↗
PubMed1997

Expression of the cyclin dependent kinase inhibitor p21WAF1/CIP1 in oesophageal squamous cell carcinomas.

To elucidate the role of CDK inhibitor p21WAF1/CIP1 in human oesophageal squamous cell carcinomas, we examined its expression immunohistochemically using surgically resected tissues from 25 patients, and have analyzed the relationship with alteration of p53 gene (F-SSCP analysis), proliferative activity (Ki-67 labelling index), frequency of apoptosis (in situ DNA nick end labelling), and degree of differentiation. P21 expression was observed in 11 cases (44%) with a percentage of positive cells ranging between 1% and 10%. Of the 25 cases, 4 cases showed > 5% of positive cells. As for the relationship with p53 gene, all 7 p53-mutation positive cases were negative for p21 expression, whereas 11 out of 18 mutation negative cases showed positive for p21 expression. As for the relationship with degree of tumour differentiation, 6 out of 8 well differentiated type cases showed positive for p21 expression. By contrast, all 8 cases of poorly differentiated type were negative for p21 expression. Frequency of apoptotic cells was significantly higher in p21 positive cases than negative cases although Ki-67 labelling index was almost the same regardless of the expression of p21. P21 expressing cells were distributed mainly in the middle layers of the invading nests, especially around the keratinization, which was almost similar to the distribution of apoptotic cells. Our results suggest that expression of p21 in human oesophageal squamous cell carcinomas is induced by a p53-dependent pathway and affects apoptosis and differentiation of carcinoma cells.

Adult↗
PubMed1997

Visceral organ involvement and extracellular matrix changes in beta 2-microglobulin amyloidosis--a comparative study with systemic AA and AL amyloidosis.

Patterns of amyloid distribution and extracellular matrix changes in the heart and gastrointestinal tract were compared among beta 2-microglobulin (B2M), AA (secondary), and AL (primary and multiple myeloma-associated) amyloidosis cases. B2M amyloid was found to be mainly distributed in the small arterioles, venules, endocardium and muscularis propria of these organs, the deposits characteristically forming subendothelial nodular lesions in the vessels. A marked increase of chondroitin sulfate (CS) was consistently detected in B2M amyloid. Heparan sulfate (HS) also showed an increase in amyloid deposits, but with less reactivity than CS in the small arterioles or venules. Basement membrane structures stained positively for laminin and collagen type IV were replaced by negative amyloid deposits. In the AL cases, the muscularis propria of the gastrointestinal tract was involved in amyloid deposits, as seen for the B2M type, but the vascular amyloid deposits were localized in the media and adventitia of larger vessels. Immunoreactivity for HS was more intense than that for CS, and no increase in laminin or collagen type IV was observed. In the AA cases, amyloid deposits were distributed in the capillaries, small arterioles, interstitium of the myocardium and mucosa. Immunoreactivity for laminin and collagen type IV was marked, and more intense than that for HS and CS. Although the existence of a direct relationship between increase in extracellular matrix material and amyloidogenesis remains to be proven, the observed variation in extracellular matrix changes in the background of each type of amyloidosis may indicate different binding sites of the amyloid precursor proteins, resulting in the specific histological features and distribution.

Adult↗
PubMed1997

Apoptotic cell death in atherosclerotic plaques of hyperlipidemic knockout mice.

In an attempt to understand the roles of apoptosis in the development of atherosclerosis, we classified lesions developed in the aortas of apo E- and LDL receptor-deficient mice, murine models of atherosclerosis, and determined frequency, spatial distribution and cell types of apoptotic cells in each lesion. Terminal deoxynucleotidyl transferase-mediated dUTP nick end labeling (TUNEL) and nuclear staining with propidium iodide were used to demonstrate apoptotic cells. Mean frequencies of TUNEL-positive cells were as follows: 0%, in Type I, 0.3% in Type II, 0.05% in Type III, 0.06% in Type IV and 0.06% in Type V lesions. Most of the TUNEL-positive cells were filled with fat and distributed in close proximity to lipid pools. The TUNEL-positive cells in the intimal side of the lipid cores were macrophages, while some of those in the adventitial side were smooth muscle cells. In conclusion, apoptosis is involved in the active turn-over of foam cells of both macrophage- and smooth muscle cell-lineage especially in the early atherosclerotic lesions of the hyperlipidemic mice.

Age Factors↗