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Biomedical subjects

A Tapia

Publications and source records attributed to A Tapia.

49 records · Page 3Linked to original sources
PubMed1977

Role of the pneumococcal autolysin (murein hydrolase) in the release of progeny bacteriophage and in the bacteriophage-induced lysis of the host cells.

The pneumococcal bacteriophage Dp-1 seems to require the activity of the N-acetylmuramic acid-L-alanine amidase of the host bacterium for the liberation of phage progeny into the medium. This conclusion is based on a series of observations indicating that the exit of progeny phage particles is prevented by conditions that specifically inhibit the activity of the pneumococcal autolysin. These inhibitory conditions are as follows: (i) growth of the bacteria on ethanolamine-containing medium; (ii) growth of the cells at pH values that inhibit penicillin-induced lysis of pneumococcal cultures and lysis in the stationary phase of growth; (iii) addition of trypsin or the autolysin-inhibitory pneumococcal Forssman antigen (lipoteichoric acid) to the growth medium before lysis; (iv) infection of an autolysin-defective pneumococcal mutant at a multiplicity of infection less than 10 (treatment of such infected mutant bacteria with wild-type autolysin from without can liberate the entrapped progeny phage particles); (v) release of phage particles and culture lysis can also be inhibited by the addition of chloramphenicol to infected cultures just before the time at which lysis would normally occur. Bacteria infected with Dp-1 under conditions nonpermissive for culture lysis and phage release secrete into the growth medium a substantial portion of their cellular Forssman antigen in the form of a macromolecular complex that has autolysin-inhibitory activity. We suggest that a phage product may trigger the bacterial autolysin by a mechanism similar to that operating during treatment of pneumococci with penicillin (Tomasz and Waks, 1975).

Amidohydrolases↗
PubMed1976

Suppression of the lytic and bactericidal effects of cell wallinhibitory antibiotics.

The bacteriolytic effect of beta-lactam antibiotics on Bacillus subtilis and on Streptococcus pneumoniae was found to be a function of the pH; lysis was suppressed if the pH of the pneumococcal culture was below 6.0 during penicillin treatment. In the case of B. subtilis, growth at pH 6.6 prevented penicillin-induced lysis. In pneumococci, the addition of trypsin to the growth medium also protected against lysis. The pH-dependent protection phenomenon resembled in several respects the antibiotic "tolerance" of pneumococci with a defective autolytic system. (i) At the pH nonpermissive for lysis, the bacteria retained their normal sensitivity to beta-lactam and to other cell wall inhibitors; however, instead of lysis, the drug-treated bacteria simply stopped growing. Loss of viability of the cells was also greatly reduced. (ii) Protection against lysis was independent of the dose and chemical nature of the cell wall inhibitors. (iii) The protection effect was reversible; lysis and loss of viability could be triggered by a postincubation of the drug-treated bacteria at the pH permissive for lysis.

Anti-Bacterial Agents↗
PubMedDate not supplied

Evolution of the vertical scar in Lejour's mastoplasty technique.

This paper presents a series of 54 consecutive cases of vertical mastoplasty carried out over the period February 1994 to April 1995. In 30 cases breast reduction was performed, in 19 pure mastopexy, and in the remaining 5, a mastopexy-breast augmentation with a silicon gel prosthesis was carried out. The parameters used for analyzing the persistence of vertical scarring were: inframammary cutaneous folds, wrinkling of the skin, and puckering at 1, 3, and 6 months during the postoperative period. An attempt has been made to establish how the vertical scar has evolved over this period. The study done by age groups as well as the study of the breast's cutaneo-glandular characteristics provides data as to with which morphotype and worst results were obtained.

Adolescent↗
PubMedDate not supplied

Improving the aesthetics of the cheek bone projection during facial lifting.

This paper shows how one of the flaps of the SMAS, which is normally eliminated during a facelift as excess tissue, can be folded up and used to improve the projection of cheekbone. The improvement of the projection of this facial area enhances the aesthetic result, when the desired aesthetic result is discreet, in rhytidectomy without having to resort to biomedical material or complex surgical techniques. Our technique, which is safe and easy to handle, simplifies this procedure, providing a long-lasting satisfactory result for both the patient and the surgeon. Our report was done following rhytidectomy on 126 female patients and after an approximately 3-year follow-up.

Adult↗