PubMed Health⌕ Search

Biomedical subjects

F Parenti

Publications and source records attributed to F Parenti.

48 records · Page 3Linked to original sources
PubMed1968

In vitro Protein Synthesis by Plastids of Phaseolus vulgaris. II. The Probable Relation Between Ribonuclease Insensitive Amino Acid Incorporation and the Presence of Intact Chloroplasts.

Amino acid incorporation into protein by chloroplasts from primary leaves of Phaseolus vulgaris L., var. Black Valentine is only partially inhibited by 400 mug/ml ribonuclease. The rate of incorporation, in the presence of ribonuclease, is progressively inhibited with time, and ceases after about half an hour. Preincubation of chloroplasts at 25 degrees , in the absence of ribonuclease, increases the inhibitory effect of ribonuclease on the initial rate of incorporation of amino acid into protein. Examination of electron micrographs of freshly prepared chloroplast suspensions shows that chloroplasts are largely intact. However, after incubation at 25 degrees for 1 hour the chloroplasts are disrupted, as indicated by loss of their stroma contents. It is concluded that the intact chloroplast membrane is relatively impermeable to ribonuclease. Amino acid incorporating activity probably becomes inhibited as the inside of the chloroplast is made accessible to ribonuclease by breakage of membranes during incubation at 25 degrees .

Journal Article↗
PubMed1968

In vitro Protein Synthesis by Plastids of Phaseolus vulgaris. III. Formation of Lamellar and Soluble Chloroplast Protein.

Chloroplasts from leaves of plants which had been grown in the dark, and then illuminated for 12 hours were isolated, and allowed to incorporate (14)C-leucine into protein, and the products of this incorporation were studied. Lamellar and soluble proteins are the principal products, and are formed in about equal amounts. Only some of the soluble proteins become heavily labeled. Those with highest specific activity have a molecular weight of the order of 140,000, while the higher molecular weight Fraction I protein has a much lower specific activity. The soluble protein as a whole does not serve as a precursor for the lamellar protein, and vice-versa, although a precursor-product relationship between a minor component of the soluble fraction and the lamellar fraction has not been ruled out. The relative protein synthesizing capabilities of chloroplasts and mitochondria are discussed with reference to the data presented.

Journal Article↗
PubMed1967

In Vitro Protein Synthesis by Plastids of Phaseolus vulgaris. I. Localization of Activity in the Chloroplasts of a Chloroplast Containing Fraction from Developing Leaves.

The incorporation of uniformly labeled leucine-(14)C into protein by a chloroplast containing fraction from developing primary leaves of bean is reported. Chloroplasts, obtained from week old plants grown in darkness, and then illuminated with white light for 12 hours, were shown to be the principal sites of incorporating activity. Incorporation may continue for 2 hours. Rates of up to 50 mumumole leucine incorporated per mg protein per hour are observed when a 1 hour assay period is used. Incorporation is only partially sensitive to ribonuclease.

Journal Article↗
PubMedDate not supplied

Diffusion of teicoplanin and vancomycin in agar.

Teicoplanin, although more active than vancomycin [by minimum inhibitory concentration (MIC)], produces smaller inhibition zones in sensitivity testing with 30-microgram disks. Our data support the hypothesis that this is due to lower diffusion of teicoplanin in agar media. After 6 hr of incubation, approximately 70% of vancomycin, but only 20% of teicoplanin entered the agar from a paper disk charged with 30 micrograms of antibiotic. This is due to a difference between the diffusion coefficients: 0.47 mm2/hr for teicoplanin and 0.72 mm2/hr for vancomycin. With the methodology used in this work, it is possible to calculate the range of concentrations of the antibiotic occurring at times likely to include the critical time--the time when the inhibition zone is formed--of most strains at any given distance from the reservoir. One can thus estimate the breakpoint diameter for a given MIC breakpoint; for example, an MIC breakpoint of less than or equal to 4 micrograms/ml would correspond to a greater than or equal to 15-mm breakpoint diameter for vancomycin (30-microgram disk) and a greater than or equal to 13-mm breakpoint diameter for teicoplanin (30-microgram disk).

Agar↗
PubMedDate not supplied

New experimental drugs for the treatment of tuberculosis.

New antitubercular agents are needed for two main purposes: to further simplify therapy (through reductions in the number of medicaments used, the number of doses administered, and the duration of treatment required), thus facilitating supervision and improving compliance, and to combat resistant mycobacteria. Reduction in the number of medicaments has been achieved by combining two or more drugs in a single tablet while retaining a degree of bioavailability similar to that of the single components. The adverse effects observed with once-weekly high doses of rifampin have limited the development of widely spaced intermittent regimens of treatment. For this reason new rifamycins have been developed that are as active as rifampin against mycobacteria but that also offer the advantage of high and prolonged serum levels and thus have the potential for once-weekly administration. The in vitro and in vivo properties of these drugs have been studied. Three classes of drugs show promise for the treatment of drug-resistant tuberculosis: spiropiperidyl rifamycin, the fluoroquinolones, and combinations of beta-lactam agents and beta-lactamase inhibitors.

Animals↗
PubMedDate not supplied

Rifampin therapy for brucellosis, flavobacterium meningitis, and cutaneous leishmaniasis.

Rifampin has a broad antibacterial spectrum. At high concentrations it also is active in vitro against protozoa, i.e., different species of Leishmania. Rifampin has been used against bacterial and occasionally protozoal infections. Addition of rifampin to a tetracycline regimen was found to reduce the number of relapses in patients with acute and chronic brucellosis. In a few cases of meningitis due to Flavobacterium meningosepticum, which failed to respond to other drugs, patients were treated successfully with rifampin administered either orally or intravenously. Rifampin at doses of greater than or equal to 600 mg daily has been administered to patients with cutaneous leishmaniasis. Healing of skin lesions was observed in the majority of treated patients. Controlled studies are needed to assess the usefulness of rifampin in this disease.

Brucellosis↗