Biomedical subjects

M Okamoto

Publications and source records attributed to M Okamoto.

At least 19 recordsLinked to original sources

PubMed1992

Preparation of a fluorescent derivative of benzoylecgonine, and preliminary studies of its application to the analysis of urine.

A sensitive high-performance liquid chromatographic method using 3-bromomethyl-6,7-dimethoxy-1-methyl-2(1H)-quinoxalinone (Br-DMEQ) as a fluorescent labeling reagent is described for the determination of benzoylecgonine (BE) and ecgonine (EC). The Br-DMEQ derivatives of BE and EC were separated on a C18 column and detected at 455 nm with excitation at 370 nm. The detection limits of the proposed method were 18.7 fmol for BE and 12.5 pmol for EC at a signal-to-noise ratio of 3. Relative standard deviations of five replicate measurements were 1.94% (10 pmol) and 2.98% (50 pmol) for BE and 6.3% (250 pmol) and 5.62% (1.25 pmol) for EC. This method was applied to the determination of BE in human urine. BE was extracted from urine by solvent extraction with chloroform-isopropyl alcohol (9:1, v/v) solution. Levels of 2.5.10(-8) M BE in urine (25 pmol/ml) could be determined.

Chromatography, High Pressure Liquid↗

PubMed1992

[Results of radiation therapy of extrahepatic bile duct carcinoma].

From January 1975 to August 1988, 40 patients with extrahepatic bile duct carcinoma were treated by external irradiation at Chiba University Hospital and the National Medical Center Hospital. Thirty-four patients (male: 20, female: 14) were evaluable. Eighteen patients were postoperative cases because the surgical margin was positive for tumor cells in the postoperative pathological examination; the other 16 were inoperable cases. Survival in postoperative and inoperable cases was not significantly different, with median survival times of 13.8 and 8.1 months, respectively. Survival in the recanalization-positive and negative-groups was significantly different (p less than 0.05) after irradiation, with median survival times of 13.5 and 6.0 months, respectively. Complications of therapy were recognized in 68% of all cases. They were mainly gastrointestinal symptoms such as nausea, vomiting, erosive gastritis and loss of appetite, but they were not severe. Distant metastasis was recognized in only 4 patients (10%): three had bony metastasis and one had supraclavicular and pulmonary hilar lymph node metastasis. Ninety percent of all cases died from hepatic failure or peritonitis carcinomatosa due to failure to obtain local control by external irradiation. A more effective modality of treatment is necessary to cure these patients.

Aged↗

PubMed1992

Group II phospholipase A2 induced by interleukin-1 beta in cultured rat gingival fibroblasts.

Previously, we reported the presence of group II-like phospholipase A2 activity in the soluble fraction of rat gingiva. In the present study, we found that treatment of rat gingival cells with human recombinant interleukin-1 beta resulted in dose-dependent stimulation of intracellular and extracellular phospholipase A2 activity. Antisera against group II phospholipase A2 totally blocked the interleukin-1 beta-induced phospholipase A2 activity, but antisera against group I phospholipase A2 did not. Moreover, immunoblot analysis showed that the induced phospholipase A2 was group II phospholipase A2. These findings suggest that the induced enzyme belongs to the group II phospholipase A2 family of proinflammatory enzymes.

Animals↗

PubMed1992

Effect of chronic pre- and post-natal low-dose ethanol exposure on brain enolase isoenzyme activities.

Sprague-Dawley dams were treated with 3 v/v % ethanol in liquid diet from the 8th day gestation through 3 weeks nursing period. Offsprings, ages 1, 2 and 3 weeks, and their dams were studied. Brain weights and their total proteins were not affected by this ethanol treatment. Total enolase activity/mg protein and its isoenzymes, i.e. non-neuron-specific, hybrid and neuron-specific, (mumol/min/mg protein) in 100,000 g supernate, were significantly lower in the treated. Additionally, enolase isoenzyme transformation was delayed.

Animals↗

PubMed1992

Antigen-induced apoptotic death of Ly-1 B cells responsible for autoimmune disease in transgenic mice.

Studies on transgenic mice expressing immunoglobulins against self-antigens have shown that self-tolerance is maintained by active elimination (clonal deletion), functional inactivation (clonal anergy) of self-reactive B cells, or a combination of both. We have established and characterized a transgenic mouse line expressing an anti-erythrocyte autoantibody. In contrast to other autoantibody transgenic lines, about 50% of the animals of this transgenic line suffer from autoimmune disease, indicating a loss of self-tolerance. Here we show that peritoneal Ly-1 B cells (also known as B-1 cells) are responsible for this autoimmune disease in our transgenic mice. A few self-reactive Ly-1 B cells that have somehow escaped the deletion mechanism expand in the peritoneum because of the absence of self-antigen. These Ly-1 B cells are eliminated in vivo by apoptosis once exposed to self-antigen. On the basis of these results we propose a novel autoantibody production mechanism whereby self-reactive B cells sequestered in compartments free of self-antigens may survive, proliferate and be activated for generation of pathogenic autoantibodies in autoimmune diseases.

Anemia, Hemolytic, Autoimmune↗

PubMed1992

Insulin resistance in Werner's syndrome.

Insulin resistance in Werner's syndrome (WS) was studied using the glucose clamp technique, and compared with physiologically aged and young subjects. Fasting immuno-reactive insulin (IRI) was increased in patients with Werner's syndrome compared with aged and young subjects. Metabolic clearance rate (MCR) of glucose was decreased in the aged and WS. A rightward shift of the dose-response curves of insulin and MCR of glucose was observed in the aged and WS with a more pronounced shift in the latter. MCR of insulin was also decreased in WS. [125I]insulin binding to erythrocytes was similar in the three groups. These results suggest that insulin resistance associated with WS is due to a post-binding defect manifested by a rightward shift of the dose-response curve of insulin-induced glucose disposal and a decrease in insulin clearance rate.

Adult↗

PubMed1992

Alternating non-cross-resistant chemotherapy for non-Hodgkin's lymphoma of intermediate-grade and high-grade malignancy. A pilot study.

Thirty-two patients with advanced non-Hodgkin's lymphoma (NHL) with aggressive histologic findings were treated with cyclophosphamide, doxorubicin, methotrexate with leucovorin rescue, bleomycin, vincristine, etoposide, ifosfamide, and prednisolone (CAMBO-VIP), in which presumably non-cross-resistant myelosuppressive and nonmyelosuppressive agents were administered during alternate weeks for 12 weeks. To ensure the high-dose intensity of the protocol, dose reduction and delay in treatment were minimized. Three patients were treated inadequately. Twenty-six (89.7%) of 29 evaluable patients had a complete response, and three had a good partial response. Relapse occurred in four patients, with a median follow-up of 29 months. The actuarial overall survival and disease-free survival were estimated to be 87.6% and 75.9%, respectively. The CAMBO-VIP treatment was well tolerated; myelosuppression was severe but transient and caused no serious infections. Side effects that affected dose intensity were oral ulceration, occurring in 28 patients, and blister formation under the thickened skin of palms and/or soles, followed by desquamation (5 patients). Hepatic toxicity was generally mild to moderate; it was severe in one patient. A 12-week regimen of CAMBO-VIP was effective for advanced NHL with aggressive histologic findings.

Adolescent↗

PubMed1992

Factor XIII-dependent generation of 5th complement component(C5)-derived monocyte chemotactic factor coinciding with plasma clotting.

Blood coagulation or plasma clotting caused generation of a monocyte chemotactic factor(s) in vitro. The chemotactic factor, of which the apparent molecular mass was 75 kDa, shared antigenicity with complement C5 and possessed the affinity to monocytes, but not to polymorphonuclear leukocytes. The generation of the chemotactic factor was hindered in the presence of a thiol enzyme inhibitor, p-chloromercuriphenyl sulfonic acid, at the concentration of 1 mmol/l, although the gelation of plasma was apparently completed. Furthermore, the generation of chemotactic factor was not observed when a plasma deficient in blood coagulation factor XIII, which is a precursor of a thiol enzyme, plasma transglutaminase, was used; and the activity normally appeared when the deficient plasma was reconstituted with purified factor XIII or with a tissue transglutaminase prior to clotting. When the human sera were injected into guinea pig skin, the serum derived from normal plasma or from the reconstituted factor XIII deficient one caused mononuclear cell infiltration, however, the serum from the deficient plasma without reconstitution infiltrated to a significantly smaller extent. These results indicated that the complement system was initiated somehow during the clotting process resulting in the generation of the C5-derived monocyte chemotactic factor in cooperation with factor XIIIa (activated factor XIII).

Animals↗

PubMed1992

Monoclonal antibodies possibly recognize conformational changes in the human erythrocyte glucose transporter.

Two monoclonal antibodies (MAG17 and MAG20) were raised against the human erythrocyte glucose transporter, which was purified on an immunoaffinity column using a polyclonal antibody to the C-terminal peptide (residues 477-492) of the glucose transporter of HepG2 cells. To obtain antibodies which recognize the native glucose transporter integrated in the membrane, hybridomas were screened both by e.l.i.s.a. with purified glucose transporter and by dot-blotting with erythrocyte membranes. The antibodies immunoprecipitated D-glucose-inhibitable [3H]cytochalasin B-photoaffinity-labelled glucose transporters, but did not recognize the transporter on Western blotting. The presence of the C-terminal peptide did not inhibit the binding of these antibodies to the glucose transporter, suggesting that the antibodies recognized sites different from the transporter C-terminus. D-Glucose (0.1-100 microM) inhibited the binding of MAG17 and MAG20 to the transporter by 50%, indicating that the conformation of the epitopes was altered allosterically by D-glucose. Cytochalasin B inhibited the binding of MAG17 to the transporter, but enhanced the binding of MAG20 at low concentrations (less than 0.02 microM). These data suggest that the glucose transporter has high- and low-affinity binding sites for D-glucose and cytochalasin B, and that binding of D-glucose and cytochalasin B induces conformational changes in the transporter. Monoclonal antibodies which recognize the tertiary structure of the glucose transporter can be used for investigating its function and structure when integrated in the membrane.

Amino Acid Sequence↗

PubMed1992

A transgenic model of autoimmune hemolytic anemia.

We made double transgenic mice bearing immunoglobulin heavy and light chain genes encoding an autoantibody against the mouse erythrocyte by the cross of C57BL/6 mice carrying the transgene for each chain of the immunoglobulin. Although no obvious disorders were found in the single-chain transgenic mice, severely anemic symptoms were found in some of the double transgenic mice, in which most B cells express, at least on their surface, the autoantibody reactive to self-antigens on the erythrocyte. Individual double-transgenic mice showed a wide variation of phenotypes between severe anemia and no symptoms. Both deletion and anergy of autoreactive B cells were seen in each individual mouse, but their relative contribution to self-tolerance was variable and not directly related to the severity of anemia or the amount of the autoantibody produced. This transgenic system provides a good autoimmune disease model for exploring its onset mechanism, and means of its treatment and prevention.

Anemia, Hemolytic↗

PubMed1992

Doppler echocardiographic measurement of cardiac output in man using mitral annulus method.

The mitral inflow method of measuring cardiac output with pulsed Doppler two-dimensional echocardiography was developed and validated against the thermodilution technique in 42 patients. A mitral inflow method combined the velocity of left ventricular inflow at the mitral annulus (apical long-axis view) with the cross-sectional area of the annulus calculated from its diameter (parasternal long-axis view). A good correlation was observed between thermodilution and Doppler measurements of cardiac output (r = 0.93). The ratio of Doppler measurements to thermodilution measurements will be between 0.76 and 1.15 for about 95% of cases. There was a good correlation between percentage change in thermal cardiac output and those in Doppler cardiac output (r = 0.95); the limits of agreement were -11.5% to 10.5%, suggesting that this method can be most useful for assessing relative changes in cardiac output.

Blood Flow Velocity↗

PubMed1992

Natural Echinococcus multilocularis infection in a Norway rat, Rattus norvegicus, in southern Hokkaido, Japan.

Forty-two rats, Rattus norvegicus, captured at a garbage dump in southern Hokkaido, Japan, were examined, and one was found to be infected with Echinococcus multilocularis. The lesions were found in the liver, lung, mesenteric lymph nodes, greater omentum and also free in the abdominal cavity. No necrosis was observed in any of the lesions, and inflammatory reactions were mild. Protoscoleces were observed in the large liver cysts. A homogenate of these cysts, when transplanted into the abdominal cavity of three Mongolian gerbils and a rat, yielded numerous fully developed protoscoleces at 4-7 months post-inoculation. Judging from this, it is postulated that the rat could become a natural intermediate host for E. multilocularis in this area.

Animals↗

PubMed1992

Nicotine-induced sensitization to ambulatory stimulant effect produced by daily administration into the ventral tegmental area and the nucleus accumbens in rats.

Bilateral injections of nicotine (30 micrograms/side) into the ventral tegmental area (VTA) and the nucleus accumbens (NACC) increased the ambulatory activity in rats. Moreover, daily injections of nicotine (10, 20 and 30 micrograms/side) into the VTA and the NACC for 6 successive days produced sensitization to the ambulatory stimulant effect of nicotine. Sensitization produced by daily injections of nicotine (20 micrograms/side) into both the sites was maintained for withdrawal periods of 10 days. Mecamylamine (2 mg/kg, i.p.), SCH23390 (0.05 mg/kg, i.p.) and spiperone (0.1 mg/kg, i.p.) antagonized nicotine-induced sensitization to the ambulatory stimulant nicotine-induced sensitization to the ambulatory stimulant effect produced by daily injections into the VTA. These results suggest that nicotine-induced sensitization to the ambulatory stimulant effect involves the stimulation of the mesolimbic dopaminergic pathway through the nicotinic acetylcholine receptor (nAChR) in the VTA and the NACC.

Animals↗

PubMed1992

Biochemical switching device: biomimetic approach and application to neural network study.

There are many examples of enzymes that share substrates or cofactors in a cyclic manner. Techniques have been developed that use cyclic enzyme systems to assay quantitatively small amounts of biochemical substances (cofactor, substrate), however, only a few studies of the control of these systems have been published. The author previously showed with computer simulations that cyclic enzyme systems have the reliability of ON-OFF types of operation (McCulloch-Pitts' neuronic equation) capable of storing short-memory, and the applicability for a switching circuit in a biocomputer. This paper introduces a unique switching mechanism of cyclic enzyme system (basic switching element), and next, building the integrated biochemical switching system being composed of the basic switching element, shows the physiological phenomenon termed 'selective elimination of synapses' generally produced as a result of low-frequency train of electrical stimuli to the synapses (Kuroda, Y. 1989) Neurochem. Int. 14, 309-319).

Electric Stimulation↗

PubMed1992

Molecular biology of rat steroid 11 beta-hydroxylase [P450(11 beta)] and aldosterone synthase [P450(11 beta, aldo)].

The molecular features of rat steroid 11 beta-hydroxylase [P450(11 beta)] and aldosterone synthase [P450(11 beta, aldo)] are discussed. P450(11 beta) is biosynthesized as a precursor form composed of 499 amino acids, having a 24-amino acid extension peptide. Two species of P450(11 beta, aldo) were identified; a precursor form of P450(11 beta, aldo)-1 is 510 amino acids long and has a 34-amino acid extension peptide, while that of P450(11 beta, aldo)-2 is 500 amino acids long and has a 24-amino acid extension peptide. The 286th amino acid of P450(11 beta, aldo)-1 is Glu, while that of P450(11 beta, aldo)-2 is Lys. The cDNA-expression studies showed that P450(11 beta, aldo)-1 had the aldosterone producing activity whereas P450(11 beta, aldo)-2 had no activity, suggesting that Glu286 of P450(11 beta, aldo) plays an important role in the catalysis. The amino acid sequence of a region in P450(11 beta) from Leu337 through Pro352 is highly conserved among the steroidogenic P450s. Functional expression studies on the cDNAs for two P450(11 beta)s showed that P450(11 beta) catalyzes the 11 beta-, 18- and 19-hydroxylations of 11-deoxycorticosterone, but not the aldosterone synthesis. P450(11 beta, aldo), on the other hand, catalyzes the conversion of 11-deoxycorticosterone to corticosterone, 18-hydroxycorticosterone and aldosterone. The two P450(11 beta)s were also shown to catalyze the conversion of 11-deoxycortisol to cortisol, 18-hydroxycortisol and cortisone.

Amino Acid Sequence↗

PubMed1992

Functional expression of cDNAs for bovine 11 beta-hydroxylase-aldosterone synthases, P450(11 beta)-2 and -3 and their chimeras.

Two molecular species of bovine P450(11 beta), P450(11 beta)-2 and P450(11 beta)-3 have been identified, in which the amino acid differences were found at the 6th, 36th and 82nd positions from the NH2-termini of the mature proteins. They catalyzed the 11 beta-, 18- and 19-hydroxylation and aldosterone formation from 11-deoxycorticosterone, and the rate of production of 18-hydroxycorticosterone and aldosterone by P450(11 beta)-3 was greater than that by P450(11 beta)-2 [Morohashi et al., J. Biochem. 107 (1990) 635-640]. In this study, chimeric clones were constructed whose 6th, 36th and 82nd amino acid residues were exchanged with each other. Two original clones and six chimeric clones were expressed in COS-7 cells, and their steroidogenic activities studied. The ratio of aldosterone or 18-hydroxycorticosterone production to corticosterone production by one clone was compared with that of the other. The ratios for the four clones having Gly36 [P450(11 beta)-3 type] were 0.08-0.22, whereas those for the clones having Ser36 [P450(11 beta)-2 type] were 0.03-0.05, suggesting that the Gly36 structure is important for aldosterone production.

Animals↗

PubMed1992

Very-low-calorie-diet therapy in severe obesity.

This study investigated the effects of very-low-calorie-diet (VLCD) therapy on body weight, plasma glucose, and lipid metabolism in severely obese patients. Ninety-one patients were subjected to VLCD therapy for 4-24 wk. Reduction of body weight was remarkable during the first 4 wk, then leveled off despite continuous treatment. Fasting plasma glucose, triglyceride, and 75-g oral glucose-tolerance test showed a significant improvement. Total cholesterol fell in the early stages but then increased more than the pretreatment level during VLCD. VLCD therapy is useful for the treatment of severe obesity.

Adult↗

PubMed1992

The effects of pravastatin on hyperlipidemia in renal transplant recipients.

Hyperlipidemia may be one of the risk factors in the development of atherosclerotic disease in renal transplant recipients. In the present study, 24 kidney recipients with hyperlipidemia were treated with an HMG-CoA reductase inhibitor, pravastatin (10 mg/day). All recipients had been treated with cyclosporine (CsA), azathioprine (Az), and prednisolone (Pred). The mean total cholesterol (T-chol) level decreased from 323 +/- 7.4 to 261 +/- 7.9 mg/dl at one month after starting treatment (P less than 0.01) and this level did not change during treatment for further 6 months. The mean LDL cholesterol level was also decreased from 205.9 +/- 11.2 to 118.7 +/- 8.1 mg/dl at 3 months after starting treatment (P less than 0.01). On the other hand, pravastatin did not affect the levels of HDL-cholesterol and triglycerides. Pravastatin did not show any effects on the white blood cell, monocyte, and lymphocyte counts, or the hemoglobin concentration (NS). One patient displayed a slight elevation of aspartate aminotransferase and alanine aminotransferase levels, but this was not sufficient to cease treatment. Pravastatin did not adversely affect the renal function or creatinine phosphokinase (CPK) levels. Two recipients developed nausea and vomiting and their treatment was stopped. Pravastatin appears to be a safe and efficacious method of treating hyperlipidemia in renal transplant recipients.

Cholesterol↗