Search PubMed⌕ Search

Biomedical subjects

T Ohta

Publications and source records attributed to T Ohta.

At least 1,351 records · Page 75Linked to original sources
PubMed1980

Amino acid diversity of immunoglobulins as a product of molecular evolution.

Based on population genetics theory of the evolution of multigene families, the sequence variability of the variable regions of immunoglobulins compiled by Kabat et al. (1976) has been analysed. An amino acid identity coefficient either within or between species is calculated separately for both the hypervariable and the framework regions. Under the somatic mutation hypothesis, the somatic component of amino acid diversity is in addition to the germ line component and should contribute an amount of change between the hypervariable and framework regions that is independent of the time since the divergence of any two immunoglobulin gene families. The relationship between the identity coefficient of the hypervariable region and that of the framework region is shown to be not in accord with such prediction. The result indicates that the rate of evolutionary accumulation of amino acid replacements in the hypervariable region is roughly three times more rapid than in the framework region and the hypervariability within a species is a necessary consequence of the high evolutionary rate.

Amino Acid Sequence↗
PubMed1980

Occurrence of ANTI-AHLG in renal transplant patients on AHLG (anti-human lymphocyte globulin).

Two patients with kidney transplants were prescribed anti-human lymphocyte gamma-globulin (AHLG) as an adjunct immunosuppressive treatment. AHLG was prepared from cultured human lymphocytes an antigen and successive anti-AHLG levels were measured using passive hemagglutination tests during and after the AHLG treatment. Anti-AHLG levels began to increase after 10-14 days of daily AHLG administration. Thereafter, the levels tends to decrease transiently by the further administration of AHLG. The titer rose again after the discontinuation of AHLG administration reaching a plateau which continued for a considerable length of time. Pretreatment levels were reverted after more than three months. The anti-sheep RBC Ab and anti-horse RBC Ab levels followed the same pattern as that seen with anti-AHLG Ab. The anti-AHLG Ab proved to be specific anti-horse gamma-globulin Ab. Alterations in the anti-AHLG levels can thus be used to monitor the optimal dosage and period of administration as well as to predict the anaphylactic reaction due to AHLG treatment. Keeping the anti-AHLG level low is mandatory to maintain good immunosuppressive conditions yet avoid anaphylactic reactions.

Adolescent↗
PubMed1980

Detection of mutagenicity of procarbazine by the host-mediated assay with polychlorinated biphenyl (aroclor 1254) as enzyme inducer.

Procarbazine [N-isoppropyl-alpha-(2-methylhydrazino)-p-toluamide] was tested for mutagenicity with Salmonella typhimurium G46 in the host-mediated assay by using male BALB/c mice pretreated orally with polychlorinated biphenyl (PCB, Aroclor 1254). Procarbazine was weakly mutagenic without PCB pretreatment, but the pretreatment greatly enhanced the mutagenicity of this compound. The administration of 500 mg PCB/kg 1 day before procarbazine dosage was suitable for the detection of the mutagenicity. Among PCB, 3-methylcholanthrene (3-MC) and phenobarbital sodium (PB), the former 2 inducers showed much stronger enhancing effects than PB. The pretreatment with 3-MC in combination with PB did not cause further enhancement compared with 3-MC alone.

Animals↗
PubMed1980

Mutagenicity screening of feed additives in the microbial system.

18 feed additives were tested for DNA-modifying effects by the repair test named "rec-assay" with Bacillus subtillis H17 (rec+) and M45 (rec-), and for mutagenicity with Escherichia coli WP2 hcr and 5 Salmonella typhimurium tester strains with the use of a top-agar overlay method. Carbadox, furazolidone, panazon and zoalene were positive in both assays. The former 3 were mutagenic for TA100, TA98 and WP2 hcr, while zoalene was mutagenic for all strains. These 4 compounds did not require a metabolic activation for their mutagenic activities. Nicarbazin was weakly mutagenic for TA1538 and TA98 with and without S9 mix. Amprolium and caprylohydroxamic acid also showed very weak mutagenicities only for TA100 with S9 mix and for WP2 hcr with and without S9 mix, resp. The mutagenic activities of carbadox, furazolidone and panazon for TA100 were reduced only by the addition of S9 mix, but not by S9 fraction or blood, whereas that of zoalene was decreased by any of the 3 factors.

Animal Feed↗
PubMed1980

A prospective study of hemodynamic changes associated with distal arterial bypass in the leg.

Twelve limbs with Buerger's disease were examined by measurement of segmental blood pressure, digital arterial oxygen saturation and flow velocity in the foot, before and after distal arterial bypass grafting. Eight out of 12 grafts were patent in a follow-up of 6 months to 2 years and one month. Patients with low distal blood pressure before operation obtained a small increase of the foot and toe pressures postoperatively, whereas patients with relatively good initial distal blood pressure were likely to acquire a remarkable recovery of the foot and toe blood pressures. In all 8 limbs with successful revascularization, blood flow velocity in the foot returned to normal, while the foot or the toe pressures remained pathological in 7 of the 8 limbs and digital arterial oxygen saturation did not revert to normal in 4 limbs, with ulceration after healing of the lesion. Postoperative normalization of the foot flow velocity was predictive of limb salvage. The most characteristic feature of peripheral arterial occlusive disease is a stagnation in the microvascular circulation and improvement of the reduced flow velocity is a goal of surgical or conservative treatment.

Adult↗
PubMed1980

Effect of reducing agents on the solubilization of renal sodium and potassium dependent ATPase with detergent.

A high concentration (0.5 M) of a reducing agent such as dithiothreitol or 2-mercaptoethanol inactivated both crude (microsomal) and purified preparations of Na+,K+-ATPase only in the presence of detergent. The concentration of SDS needed for inactivation by a reducing agent was low (around 0.3 mg/ml), and was similar to that required for activation in the absence of reduction. The subunits of the enzyme after inactivation with a reducing agent were not sedimented by centrifugation at 100,000 x g for 1 h. Electron microscopic observation of the inactivated enzyme revealed that membranous structures were dominant in the pellet obtained by centrifugation, whereas many particles were present in the supernatant. These results suggest that Na+,K+-ATPase was inactivated by reduction of disulfide bond(s) embedded within the lipid bilayer in the presence of detergent, and that the subunits of the resulting enzyme were no longer bound to the membrane.

Animals↗
PubMed1980

Purification and characterization of a poly(A) polymerase from beef liver nuclei.

Poly(A) polymerase [EC 2.7.7.19] was highly purified from beef liver nuclei by the use of column chromatographies on heparin-Sepharose 4B and Blue Dextran-Sepharose 4B. The purified enzyme showed one major protein band of the molecular weight of 57,000 in SDS polyacrylamide gel electrophoresis, which agreed with the molecular weight estimated from glycerol gradient centrifugation. The enzyme required the presence of Mn2+ for its activity but was almost completely inactive with Mg2+. It incorporated specifically ATP into polynucleotide as a sole substrate. The enzyme activity dependend entirely on the addition of exogenous polynucleotide primer. It showed certain selectivity for the primers. The most effective among the tested polynucleotides was a short poly(A), for which the Km of the enzyme was shown to be 7 microM. Poly(G, U) and short poly(U) also primed the reaction, but tRNA, phage RNA, poly(G), and poly(C) were inactive. Based on observed specificity for the primer, the role of this enzyme in the cell nuclei was discussed. Digestion of the reaction product of this enzyme by two specific exonucleases, snake venom and spleen phosphodiesterases, suggested that this enzyme catalyzed the covalent bonding of the substrate to the 3' terminus of the primer as in the manner expected for in vivo polyadenylation.

Animals↗
PubMed1980

Development of a bladder-free cuff for measuring the blood pressure of the fingers and toes.

In the present study, we investigated the technique and reliability of measuring digital blood pressure by means of a rigid, airtight container (a bladder-free cuff) and a photocell placed on the digit. As cuff pressure increased, the position of digits in the cuff was maintained in the hand by fixing one or two fingers inside the cuff and, in the foot, by using a supporting stick to keep the distance from the cuff to the bed constant. An airtight seal inside the cuff was achieved using a thin rubber sleeve and adhesive tape. Blood pressures determined by the bladder-free cuff correlated well with those obtained by the conventional cuff with bladder. By using the bladder-free cuff, blood pressure could be measured at the distal phalanx of the fingers and in all toes.

Adult↗
PubMed1980

Mechanism of cerebral arterial contraction induced by blood constituents.

In helically cut stips of cerebral, coronary, mesenteric, and renal arteries from dogs, a test solution containing hemoglobin (Hb) and soluble constituents, obtained by exposure of blood clot to distilled water, produced a dose-related contraction. The contraction of cerebral arteries was greater than that of the other arteries. Methemoglobin (metHb) caused only a slight contraction. The contractile response of cerebral arteries to the Hb-containing test solution was attenuated by aspirin (10(-5) to 2 X 10(-4) M), polypholretin phosphate (PPP, 3 X 10(-5) gm/ml), a prostaglandin (PG) antagonist, and cinanserin (10(-7) M), a serotonin antagonist. Combined treatment with these antagonists suppressed the response to the test solution, but only slightly attenuated contractions induced by K+. Phentolamine was ineffective. Contractions of measenteric arterial strips induced by the test solution were potentiated by aspirin, but were attenuated by PPP and cinanserin. Serum also produced contractions of cerebral and mesenteric arteries, which were attenuated by treatment with cinanserin or PPP. Contractile responses to Hb-containing solution and serum obtained from dogs pretreated with reserpine were weaker than those to the solutions obtained from control dogs. It may be concluded that the Hb-containing test solution releases vasoconstricting PG's from the cerebral arterial wall but vasodilating PG's from mesenteric arteries. The test solution appears to contain vasconstricting PG's and serotonin. Serum-induced contractions appear to be mediated mainly by serotonin.

Animals↗