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Biomedical subjects

T Ohta

Publications and source records attributed to T Ohta.

At least 1,315 records · Page 73Linked to original sources
PubMed1982

Allelic and nonallelic homology of a supergene family.

A model to explain the high degree of polymorphism at the major histocompatibility complex (MHC) is described. The model incorporates domain transfer between the different loci in a supergene family by either gene conversion or double unequal crossing-over. Population genetics theory is used to formulate changes in the probabilities of allelic and nonallelic gene identities and equilibrium values are obtained. The observed degree of allelic and nonallelic homology in the complex can be explained by assuming that a domain is converted at a rate of 10(-5) to 10(-6) per generation and reasonable values of other parameters. This rate of domain transfer is compatible with the observed high mutation rate at marker loci in the major histocompatibility complex.

Alleles↗
PubMed1982

Linkage disequilibrium due to random genetic drift in finite subdivided populations.

In order to clarify the mechanisms responsible for the observed linkage disequilibrium, such as that found between markers in the major histocompatibility complex of man and mouse, linkage disequilibrium between two linked loci was studied for a finite population with a subdivided structure. The infinite allele model was used. In analogy with the subdivision of the inbreeding coefficient, the linkage disequilibrium coefficient was subdivided, and various variance components of disequilibrium were defined. It was found that the disequilibrium components may get very large when migration is limited if the correlation of alleles at the two loci within a colony is taken relative to that of the entire population. In other words, with limited migration, random genetic drift of gamete types prevails in each colony. A possible test in which the variance components of disequilibrium are compared is suggested; the test discriminates between epistatic natural selection and limited migration, showing the former as the main cause of the observed linkage disequilibrium. It is pointed out that the major histocompatibility complex polymorphism is in accord with the population genetics model of multigene families that incorporate gene conversion or double unequal crossing-over between the loci in the supergene family.

Journal Article↗
PubMed1982

Duality of alpha-subunit of canine kidney sodium- and potassium-activated adenosinetriphophatase in electrophoresis.

Sodium- and potassium-activated adenosinetriphosphatase (Na+, K+-ATPase) purified from dog kidney outer medulla was examined by polyacrylamide gel electrophoresis and by photoaffinity labeling with N-(ouabain)-N'-(2-nitro-4-azidophenyl)-ethylenediamine (NAP-ouabain). The large subunit band (alpha-band) split into two bands on the gel after the enzyme was heat-treated in the presence of 1% sodium dodecylsulfate (SDS). Of the two bands (alpha I and alpha II), alpha I had the same electrophoretic mobility as the original band, while alpha II moved slightly faster. Total conversion into alpha II was not observed, about half of the original remaining as alpha I. Below 60 degree C, heat treatment did not produce alpha II. Phenylmethylsulfonyl fluoride did not prevent the appearance of alpha II. Both alpha I and alpha II were labeled with [3H]NAP-ouabain. Nonspecific incorporation of [3H]NAP-ouabain also occurred irrespective of illumination, but it was removed either by diffusion during staining and destaining of the gel or by treatment of the enzyme with trichloroacetic acid. It is tentatively concluded that the splitting of the band reflects some intrinsic differences in situ of the alpha-subunit of dog kidney membrane Na+,K+-ATPase.

Affinity Labels↗
PubMed1982

Heat-stable and fructose 1,6-bisphosphate-activated L-lactate dehydrogenase from an extremely thermophilic bacterium.

Heat-stable L-lactate dehydrogenase [EC 1.1.1.27] was purified from an extremely thermophilic bacterium belonging to the genus Thermus, and it showed an allosteric nature dependent on fructose 1,6-bisphosphate as an effector. The enzyme had a molecular weight of approximately 120,000 with a subunit molecular weight of 31,000. For pyruvate reduction, the optimal pH was found to be 4.5. At neutral pH, which is a more physiological region, little enzyme activity was observed, but marked reaction resulted from the addition of fructose 1,6-bisphosphate. This addition stabilized the enzyme toward heat treatment at up to 95 degrees C. The optimal temperature for the enzyme reaction was approximately 80 degrees C for pyruvate reduction and 95 degrees C for lactate oxidation.

Enzyme Activation↗
PubMed1982

Detection of the conformational change in the catalytic site of adenosine triphosphatase from beef liver mitochondria by affinity labeling with the dialdehyde derivative of ethenoadenosine triphosphate.

Beef liver mitochondrial F1ATPase was inactivated by the 2',3'-dialdehyde derivative of ethenoATP (epsilon ATP) in a pseudo-first order reaction. The kinetics of protection of the enzyme against inactivation by various nucleoside triphosphates (NTPs) revealed that the dial-epsilon ATP was bound to the catalytic site as an affinity label. Certain anions (sulfate or bicarbonate) were ineffective for protection. In the early phase of the reaction, inactivation was due to the binding of 1 mol dial-epsilon ATP per mol enzyme. In this phase, dial-epsilon ATP bound exclusively to the subunit beta of the enzyme, indicating that the catalytic site is in this subunit. The fluorescence of the ethenoadenosine moiety, bound exclusively to the subunit beta of the enzyme, was measured as a conformational probe of the catalytic site region. Addition of ATP or CTP to the labeled enzyme resulted in a decrease in the fluorescence intensity. GTP and other NTPs were less effective than ATP or CTP. The anions (sulfate of bicarbonate) suppressed the ability of ATP to decrease the fluorescence in a competitive manner. Quantitative analysis of these fluorescence changes suggested that they might originate from the binding of the NTP to the regulatory site of the enzyme. These findings are in good agreement with the two-site model proposed by us (Wakagi, T. & Ohta, T. (1981) J. Biochem. 89, 1205) which was deduced from the steady state kinetics of the NTPase reactions catalyzed by the F1ATPase.

Adenosine Triphosphatases↗
PubMed1982

Measurement of blood pressure in all toes in arterial occlusive disease of the leg.

In the present study, systolic blood pressure in all toes was measured by using a bladder-free cuff in 20 normal limbs and 106 limbs with arterial occlusive disease, and the clinical significance of blood pressure measurement in all toes was studied. In 97 of 106 limbs with arterial occlusion, all 5 toes showed a significantly decreased blood pressure, indicating that any toe can be used for the purpose of diagnosis of arterial occlusions. However, 41% of cases showed the difference in blood pressure of more than 15 mm Hg between any 2 toes. Great variations of blood pressure among 5 toes were observed especially in limbs with gangrene or with other skin ischemic symptoms such as cold sensitivity, numbness, or history of gangrene in the toes. In these cases, evaluation of hemodynamics in each toe is considered to be of use for prognostic study of gangrene, selection and evaluation of treatments, and follow-up study. In limbs with intermittent claudication, however, blood pressure measurement in all toes may have little value in clinical practice because of small variation among blood pressure values of 5 toes. In comparison of blood pressure values in each toe from limbs with gangrene, toes with gangrene showed a significantly lower blood pressure than toes without gangrene. However, even in these toes without gangrene, a significantly lower blood pressure was observed than in toes from limbs without gangrene. These findings indicate that severe damage to digital circulation due to an occlusive process proximal to the toes is a primarily indispensable condition for development of gangrene in arterial occlusive disease.

Adult↗
PubMed1982

[Studies on the cervicobrachial disorder among cash register operators. Part 1. Changes of characteristics of patients after improvement of working conditions].

Occupational cervicobrachial disorders (OCD) among cash register operators have become an important problem since 1969. Some improvements of working conditions, such as, shortened operating time, adoption of worker rotation system and change of mechanical registers with heavy keytouches to electronic ones with light keytouches, were introduced in 1973-1974 at supermarkets at which the authors engaged in health care activities for the prevention of the disorder. Analysis was made for characteristics of 120 cash register operators of these supermarkets suffering from OCD during the period from 1972 to 1978, with special concern for differences before and after the improvement of working conditions. The subjects were divided into three groups by the year of their first consultation, A: 1972-1973, B: 1974 and C: 1975-1976. Patients of group A had engaged in cash register operation under the working conditions before improvements, and those of group C had engaged after improvements of working conditions. The authors observed that the incidence of the disorder among group C were less than that of group A, but the proportion of severe cases to all the patients were not changed. In group C more cases with chronic onset were observed than among the other two groups, and those patients with chronic onset took longer period for recovery compared with the other patients. In patients of group C compared with those of group A fewer complaints and muscle tenderness in the hands and fingers were noticed, and more cases with lowered back strength and cinesalgia of the neck were observed. The reasons for this were considered to be that the improvement of working conditions reduced the loads to the hands, but not much reduced the loads to the neck and the back.

Adult↗
PubMed1982

[Studies on the cervicobrachial disorder among cash register operators. Part 2. A review on clinical findings and working conditions of patients].

Complaints, clinical findings and working conditions of the patients suffering from occupational cervicobrachial disorders (OCD) were discussed, with special reference to the prognosis of the patients. Subjects were 120 cash register operators with OCD engaged in supermarkets at which the authors participated in the health care activities for the prevention of the disorder. Thirty-three of them suffered from the disorder after getting well from the first onset. The authors discussed on the relationship between complaints and clinical findings of the patients and duration needed for recovery, the relationship between clinical finding and complaints of "the upper extremities" by the questionnaire of "complaints in daily life" and the relations of appearance of lowered grip strength to complaints and clinical findings. Case studies were also examined as to the influence of working conditions on the prognosis of the patients. Results were summerized as follows. 1. The severer the grade of OCD, the longer the duration needed to recover. 2. There were more complaints of arms, "the upper extremities" and "the legs", increased appearance of lowered back strength, cinesalgia of the shoulder, neck, and wrist joints, paresthesia, positiveness of Morley's test and muscle tenderness in the extensor muscles in the fingers, neck, back and so on among the patients with delayed recovery than among those recovered within 3 months. 3. Lowered back strength, muscle tenderness in the neck and in various sites of the body were observed more among the patients with many complaints of "the upper extremities" than among those without. 4. Lowered grip strength was not considered to be useful for early diagnosis of the patients. 5. Such working conditions, as carrying heavy goods and keeping upper extremities raised for a long time were considered to hamper the recovery of the disorder.

Adult↗
PubMed1982

[Basic and clinical evaluations of cefmetazole in postoperative wound infections].

The time course of the concentration of cefmetazole (CMZ) in the serum and in skin and intestinal tissues was determined after a single intravenous injection of 2 g of the drug. CMZ moved into them well. Furthermore, 41 patients with postoperative wound infection (superficial in 29 and deep in 12) were treated with CMZ 2-4 g daily. Bacteriological examination of the lesions with simultaneously carried out. As a result, 101 strains of bacteria were isolated and identified. Mixed infection was found in 27 cases (65.9%). Fifteen strains (14.9%) of E. coli, 15 (14.9%) of B. fragilis, 7 (6.9%) of Klebsiella sp. and 7 (6.9%) of Proteus sp., were the main bacteria isolated. Eight cases (19.5%) had mixed infection of E. coli and B. fragilis. The committee (3 members) evaluated CMZ to be effective in 75.6% (31 of 41 cases) and bacteria disappeared in 60.5% (23 of 38 cases). The side effects observed were pyrosis and feeling of gastric malaise in 1 case. The results suggest that CMZ is useful, which exerts an excellent effect on postoperative wound infections.

Adolescent↗
PubMed1982

Purification and immunological characterization of human pancreatic ribonuclease.

Three alkaline RNases were purified from human pancreatic juice to near homogeneity as judged by sodium dodecyl sulfate and native polyacrylamide gel electrophoreses. The molecular weights of these RNases determined by sodium dodecyl sulfate electrophoresis were 27,000, 19,000, and 13,000. The activities of these three RNases were increased by addition of Mg2+, Ca2+, Co2+, K+, Na+, spermine, and spermidine and decreased by the addition of heparin, Cu2+, and Zn2+. These RNases showed higher hydrolytic activity toward polycytidylic acid than toward polyguanylic acid, polyuridylic acid, or polyadenylic acid. The three human pancreatic RNases were immunologically identical but differed from human liver RNase, as shown by Ouchterlony double-diffusion test. Radioimmunoassay of human pancreatic RNase showed that immunologically similar RNases are present in human saliva, and serum.

Animals↗
PubMed1982

Thallium--201 myocardial imaging in Kawasaki disease.

Myocardial imaging using thallium-201 was performed in patients with Kawasaki disease. In two patients whose ECGs showed ischemic changes, the scintiscan demonstrated an area with diminished radioactivity at the site corresponding to electrocardiographic localization of the infarction. Thallium-201 myocardial imaging is useful in the diagnosis of myocardial infarction not only in adults but also in younger children.

Female↗
PubMed1982

Polyclonal increases of serum immunoglobulins and increase of immunoglobulin-bearing peripheral blood lymphocytes in children with Kawasaki disease.

Immunoglobulin-bearing peripheral blood lymphocytes were examined in 20 children with Kawasaki disease and in 13 healthy control children. Routine laboratory tests were also performed. IgG-bearing lymphocytes, IgA-bearing lymphocytes, and IgM-bearing lymphocytes increased in children with Kawasaki disease when compared with those of controls. Measurement of immunoglobulin-bearing cells in peripheral blood may be used as a clinical test in the diagnosis of Kawasaki disease.

Child↗