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Biomedical subjects

K Murakami

Publications and source records attributed to K Murakami.

At least 487 records · Page 27Linked to original sources
PubMed1995

Cytotoxicity of brefeldin A correlates with its inhibitory effect on membrane binding of COP coat proteins.

The fungal metabolite brefeldin A (BFA) causes the inhibition of protein secretion and the disruption of the structure and function of organelles along the exocytic and endocytic pathways including the Golgi complex. Such effects of BFA have been ascribed in large part to its ability to prevent recruitment of cytosolic coat proteins onto organelle membranes. Here we show that mammalian cell lines differ from one another with respect to sensitivity to this drug. The BFA sensitivity of a given cell line appears to be dependent on the species or the order from which the cell line originates, rather than on the cell line itself. In each cell line, the dose of BFA required for inhibition of cell growth and of protein secretion correlates with the dose required for inhibition of binding of beta-COP, a coat protein of COP-coated vesicles, but not that for inhibition of binding of gamma-adaptin, a component of HA-I/AP-1 adaptor of clathrin-coated vesicles. These observations suggest that: (i) there are at least two targets for BFA that differ from each other in sensitivity to this drug, (ii) the difference in the sensitivity to BFA of the beta-COP binding is determined by the difference in the structure of a target protein for this drug, and (iii) the cytotoxicity of BFA is ascribed mainly to its inhibitory effect on the membrane binding of COP-coat proteins.

3T3 Cells↗
PubMed1995

Electron microscopic evidence that axon terminals from the mediodorsal thalamic nucleus make direct synaptic contacts with callosal cells in the prelimbic cortex of the rat.

A combined study of anterograde axonal degeneration and HRP retrograde labeling has shown that there exist monosynaptic connections between afferent fibers from the mediodorsal thalamic nucleus (MD) and callosal cells in the prelimbic cortex of the rat. Degenerating axon terminals from MD made asymmetrical synaptic contacts with dendritic spines from apical dendrites of layer III pyramidal cells that were retrogradely labeled with HRP after its injection into the prelimbic cortex contralateral to MD lesions.

Afferent Pathways↗
PubMed1995

Endotoxin-induced pulmonary vascular injury is mainly mediated by activated neutrophils in rats.

Acute respiratory failure is a common complication in patients with disseminated intravascular coagulation associated with sepsis. To elucidate the role of coagulation abnormalities in acute lung injury in sepsis, we investigated the effect of anticoagulants on the pulmonary vascular injury in rat induced by lipopolysaccharide (LPS). When administered intravenously, LPS (5 mg/kg body weight) significantly increased the accumulation of 111indium-labeled neutrophils in lung 30 min after administration. Subsequently, the pulmonary vascular permeability and the serum level of fibrin and fibrinogen degradation products (E) [FDP (E)] increased and remained elevated for several hours. Neither heparin alone, heparin plus antithrombin III, or dansyl-Glu-Gly-Arg-chloromethyl ketone-treated factor Xa, a selective inhibitor of thrombin generation, prevented LPS-induced vascular injury 6 hours after LPS administration, whereas these substances significantly inhibited the increase in serum FDP (E) at that time. LPS-induced pulmonary vascular injury was significantly attenuated in rats with methotrexate-induced leukocytopenia or treated with ONO-5046, a potent granulocyte elastase inhibitor, although ONO-5046 did not inhibit the LPS-induced increase in serum FDP (E). Thus, activated leukocytes play a more important role than coagulation abnormalities in the pathogenesis of LPS-induced pulmonary vascular injury in an experimental rat model of endotoxemia.

Amino Acid Chloromethyl Ketones↗
PubMed1995

Characterization of angiotensin II receptor type 2 during differentiation and apoptosis of rat ovarian cultured granulosa cells.

We examined the change in the content of angiotensin II (AII) receptor type 2 (AT2) during differentiation and apoptosis of rat ovarian granulosa cells in culture. The AT2 content was not changed by follicle stimulating hormone (FSH), a differentiation factor of granulosa cells, but was markedly increased in FSH-free media. The cells cultured without FSH underwent internucleosomal DNA fragmentation characteristic of apoptosis, which occurs during follicle atresia. AII augmented the increase in the AT2 content in the absence of FSH. This AII-induced augmentation was suppressed by the AT2-selective antagonist PD123319 but not by Dup753, an antagonist specific for type 1 receptor, suggesting that AII up-regulates the AT2 expression via AT2 itself. These data strongly support the hypothesis that AT2 might modulate the onset and progression of follicle atresia involving apoptosis of granulosa cells.

Angiotensin II↗
PubMed1995

Determination of urinary valproylcarnitine by gas chromatography-mass spectrometry with selected-ion monitoring.

A modified method for the determination of valproylcarnitine in urine samples of patients receiving sodium valproate by gas chromatography-mass spectrometry with selected-ion monitoring is described. The chemically analogous internal standard 2-ethylpentanoylcarnitine was added to the urine samples. Valproic acid and its metabolites were removed by extraction with chloroform at pH 5.0. The samples were then applied onto a C18 Sep-Pak column. Inorganic and water soluble compounds were washed out with water. Valproylcarnitine and internal standard were eluted with methanol and were derivatized to the corresponding acyl-containing lactones by heating at 100 degrees C for 60 min in dimethylformamide. Urinary valproylcarnitine levels of epileptic patients receiving valproate were determined according to the present method. The data obtained might be useful for diagnosis of carnitine deficiency.

Calibration↗
PubMed1995

Expression of renin in coagulating glands is regulated by testosterone.

BACKGROUND: The presence of extrarenal or local renin-angiotensin system (RAS) has been noted in several tissues, although its functions have not yet been clarified. Renin from the coagulating gland (CG) is the most recently discovered local RAS and is a significant subject for investigation because large amounts of both mRNA and proteins are detected in this organ. Recently, it has been reported that testosterone influences renin synthesis in several extrarenal tissues, although it has no effect on intrarenal renin. Therefore, it is possible that CG renin is also regulated by testosterone. METHODS: Forty-four male C57BL/6 mice, aged 3 wk to 6 mo, were used in studies on the ontogeny and androgen regulation of the RAS in the CG. The tissues were fixed with Bouin's solution and paraffin sections were stained with immunohistochemical methods using antirenin antiserum. In each immunostained section, the relative number of renin-containing cells in terminal portions of the CG were counted. RESULTS: Immunoreactivity for renin was first detected at 6 wk after birth. After that time, the number of renin-containing cells gradually increased throughout the experiment. In adults, several patterns of renin immunoreactivity were demonstrated in almost all epithelial cells of CGs, specifically; (1) basolateral granular reaction, (2) diffuse immunoreactivity throughout the cytoplasm, and (3) restricted nuclear reaction. Excretory products of some terminal lumina were also found to be positive for renin. At 10 days after castration, renin-containing cells in ductal termini were decreased and remained at low levels until at 4 wk after castration. After testosterone injection, numerical values of renin-containing cells were high at 1 wk and then decreased at 2-3 wk. CONCLUSION: It is suggested that CG renin of the mouse is expressed together with sexual maturation during development and that it depends on the testis, possibly the male sex hormone.

Animals↗
PubMed1995

Heritable formation of neuroectodermal tumor in transgenic mice carrying the combined E1 region gene of adenovirus type 12 with the deregulated human renin promoter.

Adenovirus early 1 (E1) region gene products, including E1A and E1B, are required for transcriptional regulation of viral and cellular promoters in infected and transfected culture cells and for transformation of primary rodent cells. Here, we established a line of transgenic mice carrying the E1 region gene of human adenovirus type 12 under the control of the human renin promoter, in which a neuroectodermal tumor derived from retroperitoneal, olfactory, and/or pelvic regions was heritably developed with varying degrees of incidence and the phenotype was successfully passed through six generations. The transgenes were located in the region E2-E3 bands of chromosome 7 with which no genetic linkage to neuroectodermal tumors was previously demonstrated, and expressed only in the tumors but not in another tissue examined. Notably, in addition to the expression of a neural marker gene N-CAM, the three nuclear oncogenes, c-, L-, and N-myc, were coexpressed in the tumors. These results suggest that E1A and E1B are cooperatively involved in the heritable formation of neuroectodermal tumors associated with co-expression of the three sets of myc family genes.

Adenovirus E1 Proteins↗
PubMed1995

Effects of Helicobacter pylori infection on gastric mucosal defense factors in Japanese monkeys.

The pathogenic role played by Helicobacter pylori in gastric mucosal defense was investigated in Japanese monkeys infected with H. pylori. Serum gastrin levels and ammonia concentrations in gastric juice were compared in H. pylori-infected (n = 6) and control (n = 7) groups. The gastritis score, the intracellular content of periodic acid-Schiff (PAS)-positive substance and hexosamine, and the bromodeoxyuridine (BrdU) labeling index in the gastric mucosa were compared in the two groups in the antrum and the corpus. The ammonia concentration in the gastric juice was significantly higher in the infected group (P < 0.01). The gastritis scores were significantly higher in the antrum and corpus in the infected group (P < 0.01, and P < 0.05, respectively). The content of PAS-positive substance and hexosamine was significantly decreased in the antrum of the infected group compared with that in the controls (P < 0.01, and P < 0.05, respectively), but there was no significant difference between the two groups in the corpus. The BrdU labeling indices were significantly higher in the antrum and corpus of the infected group (P < 0.01, and P < 0.01, respectively). Colonization by H. pylori injures the gastric mucosa by depressing the gastric mucosal defense factors, and, consequently, the cell kinetics are accelerated.

Ammonia↗
PubMed1995

Effects of ethanol on the pancreas of disulfiram-treated rats.

To study the effects of ethanol on disulfiram-treated rats, we administered ethanol orally at a does of 2000 mg/kg, twice daily for 5 days. The administration of ethanol or disulfiram alone produced no recognizable changes in pancreatic acinar cells. Ethanol administration, in disulfiram-treated rats resulted in a decrease in the content of zymogen granules in acinar cells, and the appearance of intraplasmic vacuolization. Electron microscopically, these vacuoles appeared on the basal side of nuclei. In addition, similar vacuoles appeared in liver cells, and these vacuolizations seemed to show lipid inclusions. However, ethanol administration to disulfiram-treated rats did not cause inflammatory changes or edema in the pancreas. A comparison of blood ethanol levels in rats receiving ethanol alone and disulfiram plus ethanol showed no significant difference, but acetaldehyde levels in rats receiving ethanol plus disulfiram rats were significantly higher than those in rats receiving ethanol alone. These findings suggested that acetaldehyde caused a decrease of zymogen granules and the presence of lipid inclusions in pancreatic acinar cells.

Acetaldehyde↗
PubMed1995

Cucurbitacin glycosides from Cabeça-de-negro.

Five cucurbitacin glycosides named cabenosides D-L were isolated from 'Cabeça-de-negro', the roots of Caput nigri. Among them, the structures of cabenosides D-H were elucidated as 10 alpha-cucurbit-5-en-11-oxo-3 beta,24R,25-triol-3-O-beta-D-glucopyranoside, 10 alpha-cucurbit-5-en-24-oxo-3 beta, 11 alpha,25-triol-25-O-beta-D- glucopyranosyl, [3,O-beta-D-glucopyranoside, 3-O-beta-D-glucopyranosyl-(1-2)-beta-D-glucopyranoside, 3-O-beta-D-glucopyranosyl-(1-6)-beta-D-glucopyranoside] and 10 alpha-cucurbit-5-en-11,24-dioxo-3 beta,25-diol-25-O-beta-D- glucopyranosyl, 3-O-beta-D-glucopyranosyl-(1-6)-beta-D-glucopyranoside, respectively, on the basis of chemical and spectral evidence.

Carbohydrate Sequence↗
PubMed1995

Cucurbitacin glycosides from Caput nigri.

The chemical structures of cabenosides I-L were investigated. These are four of the 12 cucurbitacin glycosides isolated from 'Cabeça-de-negro', the roots of Caput nigri. By means of chemical analyses the structures of cabenosides I-L were elucidated as 10 alpha-cucurbit-5-ene-3 beta,11 alpha,20S,24 xi,25-pentaol [3, 25-di-O-beta-D-glucopyranoside, and 3-O-beta-D-glucopyranosyl-(1-2)-beta-D-glucopyranosyl (sophorosyl), 25-O-beta-D-glucopyranoside], and 10 alpha-cucurbit-5,20,24-triene-11-oxo-3 beta,26-diol [3-O-beta-D-glucopyranosyl-(1-6)-beta-D-glucopyranosyl (gentiobiosyl), 26-O-beta-D-glucopyranoside and 3,26-di-O-gentiobioside], respectively.

Glycosides↗
PubMed1995

The induction of micronuclei in mice hepatocytes and reticulocytes by tetrachloroethylene.

The clastogenicity of tetrachloroethylene (tetra) was detected by means of the micronucleus assay using hepatocytes and reticulocytes from ddY male mice, to understand its effects in upon hepatocellular carcinomas in mice. The frequency of micronucleated hepatocytes of mice that received a single injection of tetra after partial hepatectomy increased to levels that were significantly higher than those of controls treated with solvent. However, the micronucleus assay using peripheral blood reticulocytes from ddY male mice, revealed that tetra did not induce to a statistically significant increase in micronucleus frequency. These results suggested that tetra metabolites have a clastogenic effect in vivo upon mouse liver but not upon bone marrow cells.

Animals↗
PubMed1995

Validation of transthoracic myocardial ultrasonic tissue characterization: comparison of transthoracic and open-chest measurements of integrated backscatter.

To investigate whether myocardial integrated backscatter (IB) can be measured through the chest wall, myocardial IB parameters were measured in five adult mongrel dogs with a newly developed IB imaging system capable of measurements of myocardial IB relative to backscatter from the blood. There was no significant difference in the calibrated myocardial IB between the closed chest and the open chest conditions either in the septum or in the posterior wall if a 2.5- or 3.5-MHz frequency transducer was used. There was no significant difference in the magnitude of cyclic variation in IB between the closed chest and the open chest conditions independent of the frequency of the transducer used. These data suggest that we can accurately measure not only the magnitude of cyclic variation in IB but also the calibrated myocardial IB through the chest wall with a 2.5- or 3.5-MHz frequency transducer. Such data may validate measurements of myocardial IB parameters through the chest wall even in humans.

Algorithms↗
PubMed1995

Long-term nifedipine treatment reduces calcium overload in isolated reperfused hearts of diabetic rats.

1. Streptozotocin-induced diabetic rats showed poor post-ischemic recovery in isolated working rat hearts. 2. Diabetic rats showed myocardial Na+ accumulation after ischemia, and Ca2+ level and water content elevation after reperfusion. 3. A 6-wk nifedipine treatment improved post-ischemic recovery of cardiac parameters and prevented myocardial Na+ accumulation after ischemia and myocardial Ca2+ level and water content elevation after reperfusion of diabetic rats. 4. Results suggest that nifedipine treatment improves cardiac dysfunction in the reperfused ischemic hearts of diabetic rats through normalization of the Na+-Ca2+ imbalance and water content.

Animals↗
PubMed1995

Synergistic activation by cis-fatty acid and diacylglycerol of protein kinase C and protein phosphorylation in hippocampal slices.

cis-Unsaturated fatty acid, which activates protein kinase C in vitro, stimulates protein phosphorylation in intact hippocampal slices. Two protein bands (44,000 and 47,000 mol. wt) are particularly sensitive to cis-fatty acid and are phosphorylated in a dose- and time-dependent manner. The cis-fatty acid-stimulated protein phosphorylation can be further potentiated with diacylglycerol or 12-O-tetradecanoylphorbol 13-acetate. Several lines of evidence indicate that the cis-fatty acid-stimulated phosphorylation of these proteins is mediated by protein kinase C. First, the cis-fatty acid effect is mimicked by other protein kinase C activators such as diacylglycerol. Second, the stimulation of the phosphorylation by these activators can be blocked by staurosporine, which potently inhibits protein kinase C. Third, a concomitant application of cis-fatty acid and diacylglycerol or 12-O-tetradecanoylphorbol 13-acetate enhances the 44,000 and 47,000 mol. wt phosphorylation in a synergistic manner, which is a novel activation mode for protein kinase C. Fourth, they can be phosphorylated by purified protein kinase C (type III: alpha). Moreover, the synergistic activation of purified protein kinase C by cis-fatty acid and diacylglycerol leads to a drastic increase in the phosphorylation of these two protein bands. Two-dimensional gel electrophoresis and immunoblot analysis revealed that they are both acidic proteins. The 47,000 mol. wt band consists of two protein components; one is found to be F1/growth-associated protein-43 (pI = 4.5), and the other 47,000 mol, wt protein has broad pI ranging from 4.6 to 4.9. The 44,000 mol. wt component is a major phosphoprotein with pI of 4.8-5.1. Our results strongly indicate that cis-fatty acid can act as a regulator of endogenous protein kinase C in concert with diacylglycerol, and stimulate protein phosphorylation of its substrates such as F1/growth-associated protein-43 in the hippocampus.

Animals↗