R La Licata

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The effects of various reaction conditions and the influence of urea and its hydrolysis products on Ureaplasma ATP synthesis were assayed using of a pH stat system which avoids the unfavourable changes of the external pH. The results proved that ATP synthesis required the presence of an optimal phosphate concentration and was dependent on the urea content(More)
The localization of some enzymic activities in cell fractions of Ureaplasma urealyticum was studied. A quantitative evaluation of the effectiveness of several cell lysis procedures was obtained by using labeled membranes and sucrose density gradient centrifugation. Ultrasonic treatment was found to be the most effective procedure for lysing the cells,(More)
The pattern of free and antibody-complexed HIV antigen and the antibody profile were investigated retrospectively in 305 serum samples taken from 22 AIDS patients before and during the development of AIDS and from 40 apparently healthy seropositive individuals. Most AIDS patients were found positive for both free and complexed antigen and had high gp41(More)
Ureaplasma urealyticum lacks the conventional mechanisms for adenosine 5-triphosphate (ATP) generation, such as glycolysis or arginine breakdown, present in other mycoplasmas. The possibility that ATP may be generated in these organisms through the formation of an ion gradient coupled to urea hydrolysis has been suggested by Masover and Hayflick (Ann NY(More)
Although considerable attention has been devoted to the urea-hydrolyzing activity of Ureaplasma urealyticum, there is as yet no firmly established function for this enzyme. Present results support the idea that its activity generates a chemical gradient across the membrane which drives adenosine 5'-triphosphate synthesis through a chemiosmotic type of(More)
Adenosine triphosphatase activity of U. urealyticum is an integral membrane-bound protein which cannot be detached from the membrane by mild treatment with EDTA in low-ionic strength media nor by ionic detergents which rapidly inactivated the enzyme. The enzyme was Mg++ dependent; Mn++ and Co++ could replace Mg++ to some extent. A slight stimulatory effect(More)
The cell membranes of a T-strain of mycoplasma, obtained by ultrasonic disruption, were as effective as whole organisms in eliciting metabolism-inhibiting and complement-fixing antibodies. The soluble fraction separated from cell membranes by centrifugation at 35,000 X g showed a minor ability to elicit an antibody response as measured by metabolism(More)
Broth cultures infected with ureaplasmas for 48 hrs were unable to support further growth of reinoculated ureaplasmas even when reconstituted with fresh ureaplasma medium. The apparent toxicity of spent cultures was ascribed to the presence of non viable ureaplasmas still containing a fully active urease since all the procedures adopted to abolish or reduce(More)
263 human serum samples obtained from 9 controls and 42 patients with clinical diagnosis suggestive for toxoplasmosis were examined by means of Sabin and Feldman's dye test (DT) in comparison with complement fixation test (CF) with a whole toxoplasma antigen. 6 out of 9 controls and 21 out of 42 patients showed analogous behaviour in both methods while the(More)