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J Sakurai

Publications and source records attributed to J Sakurai.

At least 19 recordsLinked to original sources
PubMed1992

Altered regulation of Cyp1a-1 gene expression during cultivation of mouse hepatocytes in primary culture.

Alterations in Cyp1a-1 gene expression in adult C57BL/6 mouse hepatocytes were followed after transferring them to primary culture during the initial 5 days. Changing the medium to a fresh one was associated with considerable amounts of Cyp1a-1 gene mRNA with a peak at around 6 hr after the medium change, followed by a decrease to negligible levels 24 hr later. Treatment of hepatocytes with cycloheximide increased the medium change-associated mRNA expression, the levels being equivalent to those observed after treatment with 3.2-25.6 nM 3-methylcholanthrene plus cycloheximide. With increasing length of culture period, cycloheximide-aided enhancement of the medium change-associated mRNA transcription increased. Although the chemical alone did not induce Cyp1a-1 gene transcripts in hepatocytes at day 1 or 2 of cultivation, for which medium had been changed 24 hr previously, prominent induction of transcripts was evident at later periods, the levels being elevated in accordance with length of time in culture. To examine whether or not the mRNA transcribed under these culture conditions was translatable, the cells were treated with actinomycin D after washing out the cycloheximide, in order to inhibit degradation of the generated mRNA (Nemoto N and Sakurai J, Carcinogenesis 12: 2115-2121, 1991). After these procedures significant elevation of aryl hydrocarbon hydroxylase activity was observed in hepatocytes, the rise being well correlated with elevated levels of mRNA transcripts. The observations suggest that the Cyp1a-1 gene might be expressed at low levels during the initial phase of cultivation of mouse hepatocytes in primary culture. Whether this expression might be essential for mouse hepatocytes to adapt to culture conditions is unclear. The findings do suggest, however, that superinducibility of the gene expression after cycloheximide treatment might be a result of a regulatory mechanism operating after adaptation to culture.

Animals↗
PubMed1992

Effect of p-chloromercuribenzoate on Clostridium perfringens beta toxin.

p-Chloromercuribenzoate (PCMB) was shown to bind to Clostridium perfringens beta toxin. Treatment of the toxin with N-ethylmaleimide (NEM), 5,5'-dithio-bis(2-nitro-benzoic acid) (DTNB), o-iodosobenzoate (OIBA) and metal ions such as Cu2+ and Ag+ decreased the lethal activity, but PCMB did not affect the lethal activity. On the other hand, the binding of PCMB to the toxin was inhibited by DTNB and NEM in a dose-dependent manner. Furthermore, the lethal activity of beta toxin pretreated with PCMB was not blocked by treatment with NEM, DTNB, OIBA, Cu2+ and Ag+. However, the PCMB-treated toxin treated with reduced glutathione, dithiothreitol, 2-mercaptoethanol, liver homogenate or serum from mice was inactivated by NEM.

Animals↗
PubMed1992

Differences in regulation of gene expression between Cyp1a-1 and Cyp1a-2 in adult mouse hepatocytes in primary culture.

The regulation of expression of Cyp1a-1 and Cyp1a-2 genes was investigated in adult C57BL/6NCrj mouse hepatocytes for up to 5 days after transferring to either monolayer or spheroid (multi-cellular aggregate) primary culture. The expression of 3-methylcholanthrene (MCA)-induced CYP1A1 mRNA remained high during the observation period under both monolayer and spheroid culture conditions. In contrast, while levels of CYP1A2 mRNA in spheroid culture were also appreciable throughout, they rapidly decreased in monolayer culture to become negligible. An increase in intracellular cyclic nucleotide content induced CYP1A1 mRNA in the later culture period in either spheroid or monolayer cultures. A significant elevation of both basal and MCA-induced 7-ethoxycoumarin-O-deethylase, and MCA-induced aryl hydrocarbon hydroxylase and 7-methoxyresorufin-O-demethylase activities was observed in the presence of intracellular cyclic nucleotide content-increasing agents, although the extent of enhancement far exceeded that expected from the scarce changes in MCA-induced CYP1A1 mRNA levels. Basal and MCA-induced CYP1A2 mRNA expression were not changed by altering intracellular cyclic nucleotide content. The level of CYP1A1 mRNA after MCA treatment was elevated in the presence of cycloheximide. Furthermore, with increasing culture time, addition of this agent caused expression of Cyp1a-1 gene in MCA-untreated cells. In contrast, the presence of cycloheximide did not increase constitutive or MCA-induced CYP1A2 mRNA. These observations indicate that expression of Cyp1a-1 and Cyp1a-2 genes may be regulated by different mechanisms.

7-Alkoxycoumarin O-Dealkylase↗
PubMed1992

High-affinity binding of Clostridium perfringens epsilon-toxin to rat brain.

125I-epsilon-toxin showed high affinity to rat brain homogenates and synaptosomal membrane fractions, having single binding phases with dissociation constants (Kds) of 2.5 and 3.3 nM, respectively. Treatment of synaptosomal membrane fractions with pronase and neuraminidase lowered the binding of the labeled toxin, whereas treatment with trypsin and phospholipase C did not. Heating of the fractions resulted in a decrease in the binding of the toxin. These data suggest that interaction of epsilon-toxin with cell membranes in the brain is facilitated by a sialoglycoprotein. On the other hand, treatment of the membrane fractions with lipase resulted in complete loss of binding, suggesting that the interaction may require an appropriate lipid environment. These data suggest the presence of specific binding sites in brain tissue for epsilon-toxin.

Animals↗
PubMed1991

Enzyme-linked immunosorbent assay for rapid detection of toxins from Clostridium perfringens.

An enzyme-linked immunosorbent assay (ELISA) with antibodies specific to beta, epsilon and iota ib toxins of Clostridium perfringens was developed to detect beta, epsilon and iota ib toxins, respectively. The ELISA was sensitive enough to detect as little as 1.0 ng/ml of purified beta and iota ib toxins and 0.1 ng/ml of purified epsilon toxin. By means of the ELISA method, 192 isolates of C. perfringens from food samples in Japan and Thailand, and 58 isolates from patients suffering from gas gangrene or gastroenteritis were examined. One isolate from food samples in Japan, three from food samples in Thailand and five from stools of patients with gastroenteritis were C. perfringens type D. One type B and one type C were detected from the stools of patients with gastroenteritis.

ADP Ribose Transferases↗
PubMed1991

Distribution of labeled Clostridium perfringens epsilon toxin in mice.

The in vivo distribution of labeled Clostridium perfringens epsilon toxin after i.v. administration to mice was investigated. High amounts of radioactivity were found in the kidneys and the brain, and small amounts were in the heart, lungs, liver and stomach. On the other hand, the prior administration of epsilon prototoxin resulted in significant inhibition of the uptake of the radioactivity in the brain, but no effect in the other organs tested. The labeled prototoxin or toxin was dose-dependently accumulated in the brain after i.v. injection. However, the prototoxin inhibited the uptake of the toxin injected within 10 min after the administration of the prototoxin. The prototoxin also inhibited the uptake of labeled bovine serum albumin caused by the toxin in the brain. In the present paper, these data show that the toxin is specifically bound to the brain of mice.

Animals↗
PubMed1991

Increase of CYP1A1 mRNA and AHH activity by inhibitors of either protein or RNA synthesis in mouse hepatocytes in primary culture.

Regulation of CYP1A1 gene expression in mouse hepatocytes from C57/BL6 strain in primary culture was investigated with respect to aryl hydrocarbon hydroxylase (AHH) activity and mRNA levels. Small amounts of the CYP1A1 gene transcripts were detected without the presence of any known AHH inducers but after medium change. Maximal level of expression was approximately 6-9 h after the procedure, followed by a decrease to an undetectable level 24 h later. After temporary treatment of hepatocytes for 10 h with cycloheximide, an inhibitor of protein synthesis, AHH activity measured 14 h later was at a normal low level, although medium-change-associated CYP1A1 mRNA were increased by cycloheximide treatment. However, if cells were treated with either actinomycin D, alpha-amanitin or cordycepin, which are inhibitors of RNA synthesis, after exposure to cycloheximide, prominent induction of AHH activity was observed, the levels being almost equal to those for hepatocytes treated with benz[a]anthracene, a potent AHH inducer. With the same experimental protocol benz[a]anthracene-induced AHH activity was enhanced approximately 4-fold. After washing out cycloheximide and/or benz[a]anthracene, the decrease in the mRNA amounts was delayed in the presence of actinomycin D and half amounts were found even 12 h later; while without actinomycin D they reduced with a half-life of 3-4 h. The observations indicate that CYP1A1 gene expression might be regulated at the post-transcriptional level with compensatory mRNA stabilization under conditions of blocked further production, resulting in elevation of AHH activity.

Amanitins↗
PubMed1991

Regulation of mouse P(1)450 gene expression in monolayer-cultured hepatocytes from responsive and non-responsive strains.

Regulation of P(1)450 gene expression in mouse hepatocytes from responsive (C57BL/6) and non-responsive (DBA/2) strains in primary culture was investigated with respect to aryl hydrocarbon hydroxylase (AHH) activity and P450 transcript levels. Although significant induction of AHH activity in C57BL/6 mouse hepatocytes after exposure to benz[aanthracene (BA) or 2,3,7,8-tetrachlorodibenzo-p-dioxin (TCDD) was observed 24 h after the beginning of cultivation, the response was more prominent after longer periods. AHH induction in DBA/2 mouse hepatocytes by TCDD was also evident after 24 h treatment, but that by BA was delayed, only becoming significant after 3 days. Limited treatment with cycloheximide (CHI) for the initial 8 h affected AHH activity measured after 24 h; BA-induced AHH activity was decreased if the treatment started day 1 after seeding of the cells from either strain, whereas if started at day 3 the enzyme activities in hepatocytes from C57BL/6 strain were approximately doubled and those from DBA/2 increased to 130%. Treatment with dibutyryl cAMP or forskolin, a specific activator for adenyl cyclase, increased BA-induced AHH activities. 3-Methoxybenzamide, a specific inhibitor of poly(ADP-ribose) polymerase, significantly increased both basal and BA-induced AHH activities of hepatocytes from both strains at days 3 and 5, reduction of P(1)450 transcripts also being evident in the latter case. The observations indicate qualitatively similar but quantitatively different regulation of AHH induction in both responsive and non-responsive mouse strains. Furthermore the regulation changed with increasing cultivation period. Previously described regulation mechanisms in cultured cells were observed to operate a few days after seeding, possibly after adaptation of hepatocytes to the culture conditions.

Animals↗
PubMed1991

Effect of Clostridium perfringens alpha toxin on contraction of isolated guinea-pig diaphragm.

The effect of Clostridium perfringens alpha toxin on contraction induced by electric stimulation of isolated guinea-pig diaphragm was investigated. The toxin inhibited electrically stimulated contraction of the tissue in a dose- and incubation time-dependent manner. Tetrodotoxin resulted in no effect of the action of the toxin. Nifedipine dose-dependently delayed the action of the toxin, but verapamil and diltiazem did not. On the other hand, treatment of the toxin with N-acetylimidazole caused significant reduction of the inhibitory activity of the toxin on contraction, but did not cause significant loss of phospholipase C activity (PN activity) as measured by hydrolysis of p-nitrophenylphosphorylcholine. The data showed that the toxin impairs contraction of isolated guinea-pig diaphragm.

Animals↗
PubMed1991

Proline is required for transcriptional control of the aromatic hydrocarbon-inducible P(1)450 gene in C57BL/6 mouse monolayer-cultured hepatocytes.

Expression of aryl hydrocarbon hydroxylase (AHH) and the corresponding gene, Cyp1A1, or P(1)450 in mice, in C57BL/6 mouse hepatocytes in primary culture was investigated after exposure to benz[a]-anthracene with respect to proline-related metabolic regulation. When the cells were cultivated in complete Waymouth MB752/1 (Way), prominent induction of AHH by benz[a]anthracene was observed, whereas the induction was inefficient in the same but proline-deficient medium [Way-(-pro)]. Constitutive AHH activities decreased with increasing culture period. P(1)450 gene transcripts were slightly expressed when the medium was changed, independently of whether the cells were cultivated in either Way or Way(-pro), followed by decreased within 24 h and no apparent induction of AHH. However, treatment with delta 1-pyrroline-5-carboxylic acid (P5C), a biosynthetic precursor for proline, dose-dependently increased basal AHH activities in the cells cultivated in Way-(-pro). Benz[a]anthracene induction of AHH in cells cultivated in Way(-pro) was additively increased in the presence of P5C as much as with proline. Treatment with o-aminobenzaldehyde, which inactivates P5C, drastically reduced the induced AHH activities in hepatocytes cultivated in either P5C-added Way(-pro) or Way medium. Benz[a]anthracene induced both P(1)450 and P(3)450 mRNAs. Neither proline nor P5C increased the induced transcripts within 12 h after the start of benz[a]-anthracene treatment, but the two compounds increased the amounts of P(1)450 mRNA found at later time points. After treatment with actinomycin D, the half-life of the induced P(1)450 mRNA was approximately 12 h, being independent of the presence of either proline or P5C. Our observations suggest that induction of AHH after treatment with polycyclic aromatic hydrocarbon is dependent on proline-related metabolism which influences the transcriptional process of P(1)450 gene expression.

Animals↗
PubMed1991

[Marfan's syndrome with annulo-aortic ectasia and ruptured mitral chorda--a case report of combined composite valve graft replacement of the aortic root and mitral valve replacement].

We report a case of Marfan's syndrome with acute heart failure caused by a ruptured mitral chorda that was successfully treated by one operation of combined composite valve graft replacement of aortic root and mitral valve replacement (MVR). A 23-year-old man was admitted to our hospital presenting severe dyspnea and chest pain. Echocardiography and cardiac catheterization studies demonstrated marked annulo-aortic ectasia, aortic regurgitation and significant mitral regurgitation due to a ruptured chorda. In operation, it was found that a chorda of the mitral posterior leaflet had been torn, with the leaflet completely prolapsed to the left atrium, and that the aortic root was dilated to 90 mm in diameter. The ascending aorta was extensively resected leaving those areas of aortic tissue involving the coronary ostia. Then the mobilized coronary arteries were reattached to the composite graft. MVR was performed with preservation of the whole anterior and posterior mitral valve apparatus except for that small part with the torn chorda. Histopathological findings of the aortic wall and mitral valve were compatible with those of Marfan's syndrome.

Adult↗
PubMed1991

[Cardiopulmonary support in PTCA for severe coronary artery disease: its efficacy].

Percutaneous transluminal coronary angioplasty (PTCA) assisted by cardiopulmonary femorofemoral bypass was performed in 4 patients who were considered to be candidates for this technique because of their severe coronary artery diseases, including 2 with left main trunk disease, one with cardiogenic shock, and one with severe 3-vessel disease. Here we report the efficacy of cardiopulmonary support in PTCA. Case 1: An 85-year-old man with persistent unstable angina despite maximal doses of medications. Stenosis of the left anterior descending coronary artery (90%) was resolved by PTCA with cardiopulmonary bypass and intraaortic balloon pumping (IABP). Case 2: An 83-year-old man with unstable angina had high grade stenoses in the distal left main, left anterior descending and right coronary arteries. Although IABP was instituted for sustained chest discomfort and ST depression, the patient developed congestive heart failure. PTCA of the left main coronary artery with cardiopulmonary bypass was successfully performed. Case 3: A 64-year-old man with acute myocardial infarction. PTCA of the occluded left anterior descending coronary artery resulted in shock despite IABP, which was resolved by cardiopulmonary bypass with percutaneous insertion of cannulae, the technique we developed. Case 4: A 74-year-old man with unstable angina. He had a severe 3-vessel disease and a thrombus in the right coronary artery.(ABSTRACT TRUNCATED AT 250 WORDS)

Aged↗
PubMed1990

Acquisition of aryl hydrocarbon hydroxylase inducibility by aromatic hydrocarbons in monolayer-cultured hepatocytes from nonresponsive mouse strains.

The expression of P1450 and P3450 genes isolated from C57BL26 mouse liver in mouse hepatocytes from responsive (BALB/c, C3H/He, C57BL/6, and CBA) and nonresponsive (AKR, DBA/2, NZB, and NZW) strains in primary culture after exposure to aromatic hydrocarbons was investigated with respect to aryl hydrocarbon hydroxylase (AHH) activity and corresponding P450 transcript levels. Constitutive AHH activity in all strains decreased with an increasing culture period. The AHH activity of cells treated with either benz(a)anthracene, benzo(a)pyrene, 3-methylcholanthrene, or TCDD continuously or 24 h before harvesting was measured during observation periods for up to 5 days. Slight induction of AHH activity by benz(a)anthracene, benzo(a)pyrene, and 3-methylcholanthrene was observed in hepatocytes from the CBA and C3H/He strains during the first half of the observation period, followed by a steep increase thereafter. Enzyme activities in hepatocytes from BALB/c mice were the same as or lower than the control values during the first half of the observation period, and in the C57BL/6 mouse high levels of AHH activities were observed even during this period. AHH activities in hepatocytes from the AKR, DBA/2, NZB, and NZW mice after treatment with aromatic hydrocarbons were lower than control levels during the first half of the observation period; however, significant induction was observed thereafter. P450 transcripts including both P1450 and P3450 RNA species were detected when the treatment was started during the early incubation period, whereas only P1450 RNA was found at the later periods. The amounts of P1450 transcript also correlated well with AHH activity, higher levels being found after starting treatment with benz(a)anthracene at day 3 or 4 than at day 1. Our observations indicate that, although AHH induction was genetically determined in each strain, activity can be induced in hepatocytes of so-called nonresponsive as well as responsive mouse strains by treatment with aromatic hydrocarbons after transfer of the cells to primary culture.

Animals↗
PubMed1990

Contraction induced by Clostridium perfringens alpha toxin in the isolated rat ileum.

Clostridium perfringens alpha toxin caused contraction of the isolated rat ileum in a dose-dependent manner. The contraction caused by the toxin was inhibited by verapamil, nifedipine, cinnarizine, but not by tetrodotoxin or incubation in a low Na+ medium. The toxin stimulated Ca2+ uptake in the ileum in a dose-dependent manner. Nifedipine completely inhibited the Ca2+ uptake into the ileum induced by the toxin. Furthermore, TMB-8, trifluoperazine, W-7 and H-7 significantly blocked the toxin-induced contraction. On the other hand, the toxin activated de novo production of phosphatidic acid and phosphatidylinositol in the tissue. These data suggest that the toxin-induced contraction is due to an increased Ca2+ permeability across the tissue, and activation of phospholipid metabolism.

Animals↗
PubMed1990

Effect of prior treatment with Clostridium perfringens epsilon toxin inactivated by various agents on lethal, pressor and contractile activities of the toxin.

Lethal and pressor activities, and the contractile responses of rat isolated ileum to Clostridium perfringens epsilon toxin, were significantly prevented by the prior administration of epsilon toxin inactivated by 1-ethyl-3-(3-diethyl-aminopropyl) carbodiimide in the presence of glycine methyl ester (EDC), 2,4,6-trinitrobenzene sulfonic acid (TNBS), succinic anhydride (SA) and ethoxyformic anhydride (EFA). However, the prior administration of the toxin inactivated by N-acetylimidazole (NAI), tetranitromethane (TNM) and N-bromosuccinimide (NBS) resulted in no inhibition of these biological activities. These data suggest that the toxin interacts with specific site(s) on target organs or tissues. The relationship between amino acid residues and the actions of the toxin is described.

Animals↗
PubMed1990

[Mitral valve replacement with preservation of ventricular annular continuity].

We evaluated clinical effects of mitral valve replacement with preservation of ventricular annular continuity in 53 patients with isolated mitral stenosis and regurgitation. The patients were divided into 3 groups; Group 1: the patients had conventional mitral valve replacement, Group 2: with preservation of posterior leaflet ventricular annular continuity (VAC) (33 patients), and Group 3: preservation of both anterior and posterior leaflet (8 patients). Operative technique was described for pure mitral regurgitation and mitral stenosis. There was one patient died within 30 days operatively in each group. In Group 1 the patient died for poor LV function, in Group 2, the patient died for postoperative GVHD, and in Group 3, the death caused by postoperative LV rupture. We have observed no late death. Minor thromboembolization in early stage were seen in 2 cases of Group 2 and there were no apparent correlation with operative technique. Postoperative cardiac catheterization data (Pulmonary Artery wedge pressure, C.O, LVEF, LVEDV1) showed no significant difference among these 3 groups. Segmental wall contraction in left ventriculography demonstrated good contraction in Group 2 and Group 3 compared with that of Group 1. Left ventricular contraction index with heart rate corrected mean Vcf (Vcfc) and left ventricular end-systolic wall stress (sigma es) relation using two dimensional cardiac echogram demonstrated almost normal range in the groups 2 and 3. These findings suggests that mitral valve replacement with preservation of ventricular annular continuity has beneficial effects on postoperative left ventricular function and requires to be further investigated.

Adolescent↗