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Biomedical subjects

C Yasuda

Publications and source records attributed to C Yasuda.

At least 19 recordsLinked to original sources
PubMed2005

Néel temperature of quasi-low-dimensional Heisenberg antiferromagnets.

The Néel temperature T(N) of quasi-one- and quasi-two-dimensional antiferromagnetic Heisenberg models on a cubic lattice is calculated by Monte Carlo simulations as a function of interchain (interlayer) to intrachain (intralayer) coupling J(')/J down to J(')/J approximately = 10(-3). We find that T(N) obeys a modified random-phase approximationlike relation for small J(')/J with an effective universal renormalized coordination number, independent of the size of the spin. Empirical formulas describing T(N) for a wide range of J(') and useful for the analysis of experimental measurements are presented.

Journal Article↗
PubMed2004

Quantitative nested reverse transcriptase PCR vs. real-time PCR for measuring AML1/ETO (MTG8) transcripts.

A quantitative nested reverse transcriptase polymerase chain reaction (QN-RT-PCR) method was developed using a plasmid cDNA containing the AML1/ETO (MTG8) fusion transcript from Kasumi-1 cells, an acute-myelogenous leukemia cell line with the t(8;21) translocation. In this method, the plasmid was detectable at a concentration of 10(-17) m. The fusion transcript in a mixture of 10(7) Rice94 (Burkitt lymphoma cell line) cells containing two Kasumi-1 cells was detectable at 10(-17) m. In a previously published real-time PCR method, the plasmid containing the fusion transcript was detectable at 10(-16) m or higher, and 20 or more Kasumi-1 cells were detectable in 10(7) Rice94 cells. Thus, this QN-RT-PCR method is more sensitive than the real-time PCR. When the same samples were examined by real-time PCR and our QN-RT-PCR method, in one patient in clinical remission after chemotherapy and allogeneic-bone marrow transplantation (BMT), the transcript was detected by QN-RT-PCR 60 days prior to hematological relapse, in contrast to 10 days before hematological relapse by real-time PCR. The transcript level was below 10(-17) m (undetectable) with this QN-RT-PCR in patients in clinical remission after chemotherapy and BMT, while it was 10(-15)-10(-16) m in patients in clinical remission after chemotherapy alone. The quantitative difference of the transcript level in minimal residual disease (MRD) between these two different types of clinical remission was estimated to be at least 10(2)-fold. This QN-RT-PCR method is useful for predicting hematological relapse and for quantitatively estimating MRD in different types of clinical remission.

Cell Line, Tumor↗
PubMed2000

Reversible dissociation/association of D-amino acid transaminase subunits: properties of isolated active dimers and inactive monomers.

The crystal structure of dimeric D-amino acid transaminase shows that the two Trp-139 sites are located in a hydrophobic pocket at the interface between the subunits and that the two indole side chains face one another and are within 10 A of coenzyme. This enzyme prefers an aromatic character at position 139, as previously demonstrated by the finding that Phe-139 but no other substitution tested provides the maximum degree of thermostability and catalytic efficiency. Here we show that an equilibrium between active dimers and inactive monomers can be demonstrated with the W139F mutant enzyme, whereas with the wild-type enzyme the subunit interface is so tight that a study of this equilibrium is precluded. We show how the processes of dimerization of monomers and dissociation of dimers to monomers are controlled. Lower pH (5.0) favors monomer formation from dimers. Gel filtration and activity analysis show that at higher pH (7.0) the monomers combine to form active dimers with a K(d) of 0.17 microM. This assembly process is relatively slow and takes several hours for completion, thereby permitting accurate measurement of kinetics and equilibrium parameters. Absorption and circular dichroism spectra of dimers and monomers are significantly different, indicating that the environment around the cofactor is very likely altered between them. The circular dichroism peak of the W139F dimer at 418 nm is less negative than that of the wild-type enzyme in accordance with its lower visible absorbance; the circular dichroism peak of the W139F monomer at 418 nm is more negative than that of the wild-type enzyme. The dissociation of dimers to monomers has also been studied by taking advantage of these spectral differences, thus permitting the rates of the dissociation and the reassociation to be calculated and compared. 2-Mercaptoethanol assists in the conversion of monomers to dimers. The results here describe dissociation/reassociation in the dimeric enzyme under native conditions without denaturants.

Chromatography, Gel↗
PubMed1999

Evidence for the presence of major peripheral myelin glycoprotein P0 in mammalian spinal cord and a change of its glycosylation state during aging.

Glycoproteins, which react with Lens culinaris agglutinin, in the membrane preparation of various portions of brains and spinal cords, obtained from 9-week-old rats and 29-month-old rats, were comparatively analyzed by SDS-polyacrylamide gel electrophoresis. In contrast to the samples from brain, which showed similar staining patterns in the two different age groups, the glycoprotein patterns of spinal cords showed marked differences by the age of donors. The most prominent evidence is that a glycoprotein with an apparent molecular weight of 30 kDa (gp30) was detected in the aged rats, but not in the young adult rats. Based on the amino acid sequence data around the glycosylation site, the gp30 was identified as P0, which is a member of immunoglobulin superfamily and a major structural component of mammalian peripheral nerve myelin. This is the first report indicating that P0, which has been considered as a peripheral nerve-specific glycoprotein, occurs also in the spinal cord of mammals. In addition, nonglycosylated P0 molecule could be detected in the spinal cord of young adult rats by anti-P0 polyclonal antibody. These results indicate that the glycosylation state of the P0 molecule in the spinal cord changes during aging.

Aging↗
PubMed1997

Experimental studies on potentiation of the antitumor activity of 5-fluorouracil with 3'-azido-3'-deoxythymidine for the gastric cancer cell line MKN28 in vivo.

A new method of biochemical modulation of 5-fluorouracil (5-FU) with 3'-azido-3'-deoxythymidine (AZT) was studied experimentally. Nude mice transplanted with cells of the human gastric cancer cell line MKN28 were divided into 4 groups, i.e., control, 5-FU, AZT, and 5-FU plus AZT, and the antitumor activities were compared. Based on the assessment of tumor volume, significant suppression of tumor growth was observed in the 5-FU and 5-FU plus AZT groups (P<0.05, P<0.01, versus control, respectively). The thymidylate synthase (TS) inhibition rate, an index of inhibition of the de novo pathway, was significantly higher in the 5-FU and 5-FU plus AZT groups than in the control group (P<0.01), but it did not differ from the control in the AZT group. TS-bound FdUMP tended to be higher in the 5-FU plus AZT group than in the 5-FU group. The activity of thymidine kinase (TK) and the uptake ratio of 5-bromo-2'-deoxyuridine (BrdU), indices of salvage pathway activity, were significantly lower in the AZT and 5-FU plus AZT groups than in the control group (TK, P< 0.05, P < 0.01; uptake ratio of BrdU, P < 0.01, P < 0.05, respectively). There were slight losses of body weight in the 5-FU and 5-FU plus AZT groups compared with that in the control group, but no difference between the AZT and control groups in weight loss. These findings suggest that addition of AZT plays an important role in potentiating the antitumor activity of 5-FU through both blockage of a compensatory increase of activity in the salvage pathway and also an increase in TS-bound FdUMP, and has no adverse effects. Thus, the combination of 5-FU and AZT could be useful as a new modality in gastric cancer chemotherapy.

Animals↗
PubMed1995

Insulin nonattenuation of vasoactive agent-induced responses in mesangial cells from spontaneously hypertensive rats.

We recently found that insulin attenuates intracellular calcium transients and cell contraction caused by vasoactive agents in cultured rat mesangial cells. Because altered glomerular function may be causally related to the evolution of hypertension, we examined in the present study the effects of insulin on the functions of mesangial cells derived from spontaneously hypertensive rats (SHR) of 4- and 8-weeks of age. Age-matched Wistar Kyoto rats (WKY) were used as controls. Intracellular calcium concentration ([Ca2+]i) was measured with Fura-2 method in suspended mesangial cells. Pretreatment of mesangial cells with 5 micrograms/ml insulin for 120 minutes did not affect basal [Ca2+]i in either WKY or SHR mesangial cells. However, insulin pretreatment significantly attenuated [Ca2+]i transients to vasoactive agents in WKY mesangial cells. In contrast, [Ca2+]i transients to these agents were not attenuated by insulin in SHR mesangial cells. Additionally, SHR mesangial cell contraction in response to angiotensin II (Ang II) was not altered by insulin, while WKY mesangial cell contraction to Ang II was, as in normal Wistar rats, significantly reduced by insulin. Since we previously showed the possibility that the attenuation of calcium signal by insulin is via insulin-like growth factor I (IGF-I) receptor, we also examined the effect of IGF-I. In contrast to WKY mesangial cells, IGF-I-induced attenuation of [Ca2+]i responses to platelet activating factor was absent in SHR mesangial cells. [125I]-IGF-I binding in SHR mesangial cells was not significantly different from that in WKY mesangial cells.(ABSTRACT TRUNCATED AT 250 WORDS)

Angiotensin II↗
PubMed1993

[Risk factors for coronary artery disease in Japanese patients with chronic renal failure].

We examined the records of 101 Japanese patients with chronic renal failure (CRF) to determine the influence of established risk factors on the incidence of coronary artery disease (CAD). CAD was found in 25 patients (myocardial infarction in 18, significant coronary artery stenosis by coronary angiogram in 16). In patients with CAD, there were significantly more male (80% vs 58%, p < 0.05), more smokers (80% vs 41%, p < 0.0005), more diabetics (68% vs 32%, p < 0.005) and more hypertensives (92% vs 76%, p < 0.05). However, lipoprotein (a), high-density lipoprotein cholesterol, low-density lipoprotein cholesterol, or triglycerides were not significantly different between CAD group and control group. When significant risk factors were entered into a stepwise logistic regression analysis, we found a history of smoking (p = 0.0025) and the presence of diabetes (p = 0.0141) to be independent risk factors for the presence of CAD in Japanese patients with CRF.

Adult↗
PubMed1991

[Histochemical changes of islet cells of Langerhans after hepatectomy and effect of glucagon and insulin].

It has been made by a number of studies that after hepatic resection, portal factors such as insulin and glucagon play an important role in liver regeneration. We have reported hypertrophy of Langerhans islands of dogs after partial hepatectomy. In the present study we attempted to clarify the mechanism of this hypertrophy. In a control group, a forty-percent hepatectomy was carried out. One and four weeks after surgery, 0.5g/kg of glucose was administered intravenously followed by a blood sampling from the portal vein to measure the changes of glucose, insulin and glucagon respectively. In addition area changes of the islets of Langerhans after the operation were measured with PAP technique. In a GI group, the same experiment as in the control group was done and 1mg of glucagon and 2IU/kg of insulin were administered every morning after the operation. The following results were obtained. In the GI group, there were no decrease in portal plasma insulin level and no enlargement of the sizes of the islets four weeks after surgery.

Animals↗
PubMed1990

[A case of prolonged jaundice after surgical treatment of obstructive jaundice caused by a carcinoma of the head of the pancreas relieved with dibutyryl cyclic AMP].

Recently, we experienced a case of obstructive jaundice caused by a carcinoma of the head of the pancreas which could not be relieved by reduction surgery. The operation performed was a cholecystectomy and supraduodenal choledochotomy with T-tube insertion. Glucagon and insulin were, therefore, administered with the aim towards the recovery of the liver function to be induced by the enhancement of the liver regeneration. The treatment, however, was not effective. Then, dibutyryl cyclic AMP was administered to the case by intravenous drip infusions at the rate of 5 micrograms/kg/min. Thereafter, the value of serum total bilirubin was reduced remarkably. A prolonged and intense obstructive jaundice is generally accompanied by damage to the liver function, and the condition carries a high risk of postoperative complication. In this paper, the effectiveness of dibutyryl cyclic AMP on liver cell damage caused by prolonged obstructive jaundice are reported.

Aged↗
PubMed1990

Effect of glucagon on bile acid metabolism after resection of liver cancer in patients with cirrhosis.

After hepatectomy patients with cirrhosis and liver cancer may develop progressive hepatic dysfunction and eventually hepatic failure. Insulin and glucagon are often used to treat certain kinds of hepatic dysfunction and hepatic insufficiency. We investigated the effect of glucagon on bile acid metabolism and pancreatic endocrine function. In 7 patients with severe cirrhosis and cancer of the liver, 1 mg of glucagon was injected intravenously pre- and post-operatively, and total bile acids, C-AMP, and bile acid fractions were determined. In the pre-operative glucagon tolerance test, the C-AMP level rose from a baseline of 14 +/- 0.8 PMol/ml to 362 +/- 94 PMol/ml 30 min after the injection of glucagon (p less than 0.01); and the level of total bile acids decreased from a baseline of 28 +/- 9 microMol/ml to 11 +/- 3 microMol/ml 60 min after the injection of glucagon. The post-operative C-AMP level increased from a baseline of 13 +/- 1 PMol/ml to 192 +/- 58 PMol/ml level of 30 min after the injection of glucagon (p less than 0.01), and the post-operative level of total bile acids decreased from a baseline of 64 +/- 20 microMol/ml to 26 +/- 7 microMol/ml 60 min after the injection of glucagon. There was a significant correlation between the 5-min increment ratio of C-AMP and the decrement ratio of total bile acids (p less than 0.01).(ABSTRACT TRUNCATED AT 250 WORDS)

Bile Acids and Salts↗
PubMed1990

[Clinical studies on hypercreatine phosphokinasemia in emergency diseases].

Unexplained serum creatine phosphokinase (CPK) elevation is not a rare clinical problem, especially in emergency diseases. We studied hypercreatine phosphokinasemia (hyper-CPK-emia) in 161 cases of emergency diseases. Correlations between CPK and various laboratory data, various conditions were investigated. The hyper-CPK-emia was found to obtain no correlations with GPT, GOT, LDH, creatinine and body temperature. For this reason, we could not discover the unknown factors of which contributed to elevate the serum CPK. The sources of the serum CPK in these diseases were concluded to be the skeletal muscle. This is based on the facts that CPK MM (muscle type) is specifically increased among the CPK isozymes. The elevation of serum CPK activity in emergency diseases was considered to result from muscle hypoxia due to severe stress and general circulatory failure.

Adolescent↗
PubMed1990

Effect of intravenously administered fat emulsion on liver function in totally depancreatized dogs.

Total Pancreatectomy was performed under nembutal anesthesia in 16 adult mongrel dogs after a 24-hour fast, and the depancreatized dogs were given parenteral nutrition containing fat emulsion. Serum lipids, intravenous fat tolerance and post-heparin lipolytic activity were determined and liver biopsy was done to demonstrate the presence or absence of fatty liver. The animals were divided into three groups: group A (n = 6) received fat emulsion 1 g/kg/day; group B (n = 5), fat emulsion 2 g/kg/day; and group C (n = 5), no fat emulsion. Blood levels of cholesterol and phospholipid were increased in group B, while only a mild elevation of the blood triglyceride (TG) level was noted in group A. In group C, cholesterol and phospholipid levels were decreased, and hypoglycemia was liable to occur. The rate of disappearance of blood fat (K2) was decreased two weeks after surgery in group B, but there were no significant change in the other two groups. These findings suggest that if insulin is present, the administration of fat emulsion will not cause fatty liver.

Animals↗
PubMed1990

[Two cases of allergic granulomatosis and angiitis (AGA); Churg-Strauss syndrome].

AGA is an angiitis syndrome that has some characteristic features, for example preceding asthma and polyneuritis. And histological findings are granulomatous angiitis or extravascular granuloma. We report two typical cases of AGA. Case 1; 51-year-old woman had been suffering from asthmatic dyspnea for one year and developed in 1987 multiple neuritis in her extremities. Eosinophilia and high level of IgE were noted. Pathologic diagnosis of the biopsied right calf muscle specimen was granulomatous angiitis. Case 2; 40-year-old woman had been suffering from asthmatic dyspnea for two years. She complained of severe cough and myalgia in 1986 and her chest X-ray showed homogeneous shadows in right upper and left lower fields. And her blood showed eosinophilia and high level of IgE. The histology of the biopsied subcutaneous nodules of hands showed extravascular granuloma. These two cases had specific features of AGA. About symptoms of angiitis, case 1 showed multiple neuritis and case 2 had subcutaneous nodules of hands. About laboratory data, case 1 showed WBC count of 9400/mm3 with 85% eosinophils and high level of IgE at 1400 IU/ml, case 2 had WBC count of 13200/mm3 with 22% eosinophils and IgE at 846 IU/ml. The vary of eosinophil count and IgE level were related to the degree and course of illness. These symptoms and laboratory data, except neuritis, improved by an administration of prednisolone. In early stage of AGA, prednisolone is effective, so the criteria of AGA and usage of corticosteroids must be considered.

Adult↗
PubMed1990

[Effect of glucagon on bile acid after hepatectomy in patients with hepatocellular carcinoma associated with cirrhosis].

Hepatic function frequently becomes worse, after hepatectomy in patients with hepatocellular carcinoma associated with cirrhosis. We usually use insulin and glucagon to treat patients with poor hepatic function, so we examined hepatic function in these patients in relation to bile acid metabolism. 1) Total serum bile acid levels were increased in patients with cirrhosis, and serum GCDCA, TCDCA values were especially high. After surgery, they rose even higher. 2) Glucagon was shown to stimulate C-AMP and decreased total serum bile acid, and especially serum GCDCA and TCDCA values.

Bile Acids and Salts↗
PubMed1989

[Effects of glucagon and insulin on poly(ADP-ribose) polymerase activity and blood ketone body ratio after partial hepatectomy in rats].

The effects of glucagon and insulin on liver nuclear poly(ADP-ribose) polymerase activity and blood ketone body ratio after rat partial (68%) hepatectomy were examined. Liver weight regeneration rate was enhanced by glucagon and insulin after 5th posthepatectomy day. The maximal value of poly(ADP-ribose) polymerase activity without glucagon and insulin was revealed as 368 +/- 64 pmole/mg/min on 5 days after the hepatectomy. In contrast, the enzyme activity with glucagon and insulin reached to the peak value as 253 +/- 42 pmole/mg/min on 2 days after the hepatectomy. The amounts of DNA per nuclear protein showed similar changes with the changes of poly (ADP-ribose) polymerase activity after the hepatectomy. Blood ketone body ratio showed almost similar changes in both groups, except transitional decrease in the group without glucagon and insulin on 5th postoperative day. It is suggested that, to promote remnant liver regeneration, the combined therapy of glucagon and insulin may act directly to nucleic acid metabolism through the changes of poly(ADP-ribose) polymerase activity and preserve energy charge level by the suppression of NAD consumption by massive poly(ADP-ribose) formation.

Animals↗
PubMed1989

[Anesthetic experience of a child with moyamoya disease].

The authors report four anesthetic experiences of a child with moyamoya disease for two occasions of angiography and bilateral encephalo-duro-arterio-synangiosis (EDAS). For angiography anesthesia was maintained with inhalation of halothane-nitrous oxide-oxygen under spontaneous respiration. During the first angiography PaCO2 was 59.5mmHg and 55.2mmHg and it was 56.0mmHg during the second angiography. For EDAS, anesthesia was managed under controlled ventilation and avoiding hyperventilation. Blood pressure was stable. The patient awoke well. Under anesthetic management of a child with moyamoya disease who has normal cardiopulmonary function, the significant factor causing brain ischemia is hyperventilation.

Anesthesia↗