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Biomedical subjects

Z Samra

Publications and source records attributed to Z Samra.

114 records · Page 7Linked to original sources
PubMed1978

Transport of tetracyclines through the bacterial cell membrane assayed by fluorescence: a study with susceptible and resistant strains of Staphylococcus aureus and Escherichia coli.

The fluorescence of 12 tetracyclines in buffered solutions was measured by excitation at 400 nm and emission at 520 nm. The fluorescence varied markedly for different tetracyclines at equivalent concentrations. Demethylchlortetracycline exhibited more fluorescence than both chlortetracycline and demthyltetracycline; minocycline was virtually non-fluorescent at the conditions of the study. Fluorescence was highly dependent on the polarity of the solvent; when the buffer solution in water was replaced by a solvent containing 50% methanol, fluorescence increased significantly, but to various degrees for different tetracyclines. The most striking influence of the addition of methanol was observed for doxycycline (5-oxy 6-deoxy-tetracycline), whereas the influence on anhydrotetracycline was negligible. When suspensions of a susceptible strain of Staphylococcus aureus were added to solutions of tetracyclines, membrane permeation of the drugs could be monitored by an increase in fluorescence. This increase varied strikingly with the different drugs and could not be correlated with the concentrations for 50% growth inhibition (Ki). This might be due to the quantitative variations in the intracellular level corresponding to a certain external concentration of the respective drug. When tetracycline-resistant strains of S. aureus and Escherichia coli were exposed to tetracycline, the intensity of fluorescence observed was less than for the corresponding susceptible strains; in spite of this, the quantitative differences of fluorescence exhibited by the susceptible and resistant strains seemed slight in relation to the differences in susceptibility. It was demonstrated that minocycline inhibits the membrane transport of tetracycline in S. aureus and E. coli. This inhibition seems to be competitive for S. aureus, but not for E. coli.

Biological Transport↗
PubMed1972

Influence of magnesium and manganese on some biological and physical properties of tetracycline.

Accumulation of (3)H-tetracycline in nonproliferating cells of susceptible and resistant strains of Escherichia coli and Staphylococcus aureus in tris(hydroxymethyl)aminomethane (Tris) buffer (10 mm, pH 7.5) was significantly decreased in the presence of 5 to 40 mm MgCl(2) and increased in the presence of 5 to 10 mm MnCl(2). When the bacteria first accumulated (3)H-tetracycline in plain Tris.HCl, and the metal salts were thereafter added, a prompt decrease or increase in radioactivity of the cells was observed after the addition of Mg(2+) or Mn(2+), respectively. In phosphate buffer (10 mm, pH 7.5), the effect of Mg(2+) was delayed. Three minutes after addition of (3)H-tetracycline, uptake was as in the control cell suspension, but thereafter it dropped rapidly. When (3)H-tetracycline was incubated with Mg(2+) before addition to the bacterial suspension, uptake was scarcely measurable. The addition of Mg(2+) to growing cultures of S. aureus and E. coli caused a marked decrease in susceptibility; in contrast, no increase in susceptibility could be demonstrated when Mn(2+) was added. It was also demonstrated that Mg(2+) and Mn(2+) had distinct influences on the absorption spectrum, the optical rotatory dispersion, the circular dichroism, and the lipid solubility of tetracycline.

Absorption↗
PubMedDate not supplied

Isolation of Chlamydia trachomatis from prostatic tissue of patients undergoing transurethral prostatectomy.

Chlamydia trachomatis was isolated from three of 100 prostatic tissue specimens obtained from patients undergoing transurethral resection of the prostate. All examined patients were free from symptoms of urethral or prostatic inflammation. Our findings are in accordance with the high incidence of asymptomatic chlamydial infection of the lower genital tract and the increasing evidence that C. trachomatis can cause infection of the prostate.

Aged↗
PubMedDate not supplied

Etiology of acute pelvic inflammatory disease proven by laparoscopy.

BACKGROUND: Only a few studies have investigated the etiology of acute pelvic inflammatory disease (PID) in laparoscopy-proven cases using pelvic samples for culture. Most of these studies were conducted in North America and Scandinavia. GOAL OF THE STUDY: To study the microbial etiology of laparoscopy-proven acute pelvic inflammatory disease in Israeli women. STUDY DESIGN: A prospective survey of women admitted to a hospital for treatment of acute pelvic inflammatory disease. All diagnoses were laparoscopy confirmed. Specimens for culture were obtained from the pelvic cavity via the laparoscope, and two serum samples were sent for serologic studies. RESULTS: Forty patients were studied. Their mean age was 34.4 years of age, and 27.5% had a history of PID. Chlamydia trachomatis infection was diagnosed in 14 (35%) patients (group A). Facultative and/or anaerobic bacteria were isolated from pelvic specimens of 7 (17.5%) patients (group B), one of these patients also had positive chlamydial serology. Mycoplasma hominis was cultured from a pelvic specimen of one woman, and herpes simplex virus grew from a pelvic sample of another patient in whom C. trachomatis was also found. In 19 (47.5%) women, the microbial etiology could not be determined (group C). In no case was Neisseria gonorrhoeae isolated. Stage I (mild) PID was diagnosed most often in group A (75% vs. 14% in group B [P < 0.02]), whereas the opposite was true for stage III (severe) PID (71.4% in group B vs 25% in group A [P = 0.07]). Tubal abscess was mainly diagnosed in group B patients (57% vs 16.6% in group A [P = 0.09]). CONCLUSION: In Israel, C. trachomatis is the most common cause of PID, while gonococci are rarely involved in this infection.

Acute Disease↗