Biomedical subjects
Publications and source records attributed to M Kohno.
A 36-year-old woman with systemic lupus erythematosus (SLE) developed septicaemia and subsequently suppurative coxitis due to Salmonella typhimurium. Although systemic treatment with antibiotics eradicated salmonella from the arterial blood, cup arthroplasty and irrigation of the operative wounds with effective antibiotics were needed for eradication of the organism from the affected joints.
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In 28 patients (pts) (5 normal subjects (N), 12 pts with valvular heart disease, 6 with cardiomyopathy, and 5 with ischemic heart disease), left ventricular (LV) pressure was measured using Millar's catheter tip transducer simultaneously with LV posterior wall thickness (W) by echocardiography. After the control recording, LV peak systolic pressure was altered by about 30 mmHg from the control level by angiotensin (20 ng/kg/min) or nitroprusside (1 gamma/kg/min) to attain two (18 pts) or three (10 pts) different end-systolic pressure points, determined after the steady state was achieved. LV end-systolic pressure and wall thickness (P-W) relation a the three different end-systolic pressure points was found to be linear (r = 0.996) in each of the 10 pts, suggesting that end-systolic P-W relation is independent of afterload. Isoproterenol infused in 4 pts, which led to an increase in peak positive (+) dp/dt by a mean of 28%, increased the slope of the P-W relation by 43.4% of the control value (P less than 0.001), while propranolol, which led to a decrease in peak (+) dp/dt by a mean of 16.7%, reduced the slope by 27.3% (p less than 0.001). This indicates the sensitiveness of the slope of P-W relation to the inotropic change of the myocardium. In N, the slope of the P-W relation was -29.7 +/0 6.0 mmHg/mm (mean +/- SD), while the value in 4 pts with decreased functional capacity (NYHA III or IV) was significantly lower (-13.7 +/- 2.9 mmHg/mm; p less than 0.001). Thus, the present study suggests that the slope of the end-systolic P-W relation is useful in assessing regional myocardial contractility in man.
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In order to obtain further evidence for the modulatory role of dopamine in chemoreceptors, effects of haloperidol, a potent dopamine antagonist, on chemoreceptor reflex ventilatory response were studied in the rabbit carotid body. An injection of 30 microgram of haloperidol into the external carotid artery induced evident ventilatory excitation which became more marked and sustained at a higher dose. The response was produced by blockade inhibitory dopamine receptors since it was completely abolished in the catecholamine depleted animals. The NaCN-induced excitation of ventilation was potentiated by prior treatment of the carotid body with haloperidol, whereas the treatment blocked the induction of the postexcitatory depression of ventilation. The results indicate the negative feedback as the most possible mechanism by which dopamine exerts its suppressor effect on chemoreceptor nerve activity.
Two DNA polymerases were detected in Tetrahymena pyriformis, strain GL. One (enzyme I) was sensitive to N-ethylmaleimide, while the other (enzyme II) was insensitive. The molecular weight of the enzymes, as determined by glycerol gradient centrifugation analysis, were approximately 130,000 and 70,000, respectively. Optimal concentration of MgCl2 was 10mM for enzyme I and 18mM for enzyme II. KCl inhibited enzyme I but stimulated enzyme II. Poly (dA-dT) served effectively as a template for enzyme I, while poly(dA).(dT)12-18 was an effective template for enzyme II. Enzyme I activity increased with cell growth and sharply declined after the cells reached the stationary phase. On the other hand, enzyme II activity appeared only at the end of log phase. In cells synchronized by starvation-refeeding technique enzyme I was markedly stimulated in correspondence to the rate of DNA synthesis, whereas the level of enzyme II activity changed to lesser extent. By ethidium bromide treatment, only enzyme I activity was induced.
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A procedure was established whereby most of the major viral proteins were isolated to apparent homogeneity in biologically and immunologically active forms from a single batch of avian sarcoma virus QV2. For the initial step of purification, gently disrupted virions were fractionated by CsCl centrifugation into envelope proteins, RNA-dependent DNA polymerase, and viral core proteins. Further purification of envelope glycoproteins and DNA polymerase was performed by affinity chromatography on agarose columns cross-linked with plant lectins and poly(C), respectively. On the other hand, core proteins were fractionated by a combination of gel filtration and ion-exchange column chromatography into components p27, p19, and p15. The core protein p15 thus isolated retained proteolytic activity even after storage for 6 months. The present study also demonstrated that QV2 p19 is structurally altered from the corresponding protein of avian myeloblastosis virus (AMV), a reference avian leukosis-sarcoma virus having a well-characterized polypeptide composition.
1. The RNA-dependent DNA polymerase associated with cytoplasmic A-type particles of murine mammary tumor virus was isolated to near homogeneity by a procedure which includes dissociation of proteins from RNA by centrifugation in a step gradient of cesium chloride, followed by an affinity chromatography on poly(rC)-agarose column. Two species of DNA polymerase were separated by the chromatography: enzyme I in 0.55 M NaCl and enzyme II in 0.80 M NaCl eluate, respectively. 2. The purified DNA polymerases consist of two major polypeptides, with molecular weights of 94,000 and 42,000, as the intrinsic subunits. Both enzyme protomers with a sedimentation coefficient of 6.3--6.4 S and a molecular weight of 115,000--120,000 associate to form active oligomers in low-ionic-strength buffer. 3. Both enzymes catalyzed the hydrolysis of RNA in RNA . DNA hybrids as well as the RNA-dependent synthesis of DNA; these are the intrinsic activities of the reverse transcriptase from B-type particles of murine mammary tumor virus as well as from avian and mammalian C-type oncornaviruses. The general catalytic properties are similar to those of the enzyme from B-type particles. Compared with DNA polymerases I, DNA polymerase II exhibited a high affinity for all the template-primers tested and, in addition, a high preference for (rC)N . (dG)12--18.
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An RNA-directed DNA polymerase was found to be associated with intracytoplasmic A-particles from DBA/2 mouse leukemia cells. The enzyme activity was detected after disrupting the purified particles with 2 M NaCl-20 mM dithiothreitol. The presence of a divalent cation and all four deoxyribonucleoside triphosphates was essential for this enzyme activity. The enzyme had a clear preference for Mg2+ over Mn2+. Cesium sulfate isopycnic gradient centrifugation of the DNA product synthesized in the actinomycin D-containing reaction revealed the presence of DNA-RNA hybrid. Furthermore, the purified DNA product was found to hybridize with RNA isolated from A-particles. These observations strongly indicate that the endogenous A-particle RNA serves as the template for the DNA polymerase.
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