Search PubMed⌕ Search

Biomedical subjects

M Afnan

Publications and source records attributed to M Afnan.

43 records · Page 3Linked to original sources
PubMed1991

Synergistic killing of gram-negative bacilli by cefotaxime, its desacetyl metabolite and human polymorphonuclear neutrophils.

Using an in-vitro model the effects of sub-MIC cefotaxime and its desacetyl metabolite singly and in combination on killing of E. coli by PMNs were studied. Our purpose was to determine if the parent compound and its metabolite had a synergistic effect on killing of E. coli by PMNs. Thymidine-labelled serum resistant Escherichia coli 018:K1:H7 were incubated during log phase growth with varying sub-MICs (1/2, 1/8, 1/32) of cefotaxime, its desacetyl metabolite and both agents together, or phosphate buffered saline (PBS) as a control for 90 min at 37 degrees C. The bacteria were then washed and a series of opsonization experiments was performed using intact and sonicated PMNs. Killing of bacteria was determined at 3, 10 and 20 min. Uptake and killing of bacteria by PMNs were measured using standard techniques. Pre-treatment of E. coli with cefotaxime alone and desacetyl cefotaxime and cefotaxime together resulted in significantly enhanced bacterial killing by PMNs at all three exposure times to PMNs. Pre-treatment of the bacteria with sub-MICs of desacetyl cefotaxime alone showed enhanced killing only after exposure for three minutes. In all cases, any increased killing was independent of ingestion by the phagocytes. The opsonization experiments demonstrated that contact between bacteria and PMNs was necessary for optimal killing to occur. The enhanced killing of the sub-MIC antibiotic pre-treated bacteria was seen even when sonicated PMNs were used. The extent of bacterial killing, however, was less than that seen with intact PMNs.

Cefotaxime↗
PubMed1991

Mechanisms of interaction among subinhibitory concentrations of antibiotics, human polymorphonuclear neutrophils, and gram-negative bacilli.

Our hypothesis was that pretreatment of bacteria with subinhibitory concentrations (sub-MICs) of antibiotics enhances the susceptibility of the organisms to killing by human polymorphonuclear neutrophils (PMNs). Our purpose was to study a variety of drugs with different mechanisms of action and to determine whether the mechanism and locus of action altered the sub-MIC effect. The following outcome measures were used: ingestion and killing of bacteria by PMNs, bacterial killing in the absence of phagosome formation, and binding requirements of the bacteria to PMNs. The antibiotics used were representative of a variety of classes, including beta-lactams (piperacillin and imipenem) and quinolones (ciprofloxacin). Bacterial uptake and killing were measured by using standard techniques, and results were analyzed by using the analysis-of-variance technique and Dunnett's t test. Pretreatment of Escherichia coli with all drugs showed significantly enhanced killing of bacteria by PMNs, which was independent of ingestion by the phagocytes. Even in the absence of phagosome formation, statistically significant killing persisted with piperacillin-pretreated bacteria but not with imipenem- or ciprofloxacin-pretreated organisms. The opsonization experiments showed that contact between bacteria and PMNs was necessary for killing to occur. The sub-MIC effect appears to be independent of the locus or mechanism of action of the antibiotic. It results in enhanced killing by PMNs which is independent of ingestion and also may persist even in the absence of phagosome formation. Killing is dependent upon specific contact between bacteria and an intact phagocyte.

Anti-Bacterial Agents↗
PubMed1991

Chemotactic inhibitors in sera of patients with neoplastic disease.

Our objective was to define the functional characteristics of chemotactic inhibitors in sera of patients with various neoplastic diseases. Fifty-nine patients were studied: lung cancer (15), breast cancer (11), lymphoma (20), leukemia (13). Chemotaxis and random motility were measured using a modified agarose technique with C5a and a bacterial filtrate of E. coli as the chemoattractants. Two types of inhibitors were found: chemotactic factor inhibitors and cell-directed inhibitors. The type of inhibitor as well as the specificity of the inhibitor for the chemoattractant (C5a or bacterial filtrate) varied depending upon the underlying neoplasm. Cell-directed inhibitors were reversible and none of the inhibitors affected random motility. Contrary to previous reports, the chemotactic factor inhibitors were heat-stable (p less than 0.001). Morphometric analysis of inhibited and non-inhibited cells using scanning electron photomicrographs showed a significant alteration in shape of the inhibited cells (p less than 0.003). The results indicate greater heterogeneity of the chemotactic inhibitors than was previously thought, as well as a tumour-dependent specificity of the inhibitors for the chemoattractants.

Breast Neoplasms↗
PubMed1984

Granulosa cell steroidogenesis before in vitro fertilization.

Endocrine and gametogenic functions of the ovulatory follicle may be linked. To verify this, we studied granulosa cell steroidogenesis in relation to oocyte fertilization and preimplantation embryo development in vitro. Multiple follicles were stimulated in in vitro fertilization patients with clomiphene citrate and ovulation was induced with human chorionic gonadotropin (hCG). Oocytes were fertilized with husband's sperm and normal embryos were replaced 48 h later. Granulosa cells were separated from follicular fluid from 64 follicles and incubated for 3 h with and without aromatase substrate (1 microM testosterone). Progesterone and estradiol levels were measured in follicular fluid and incubation medium. Follicular fluid steroid levels and granulosa cell steroidogenesis showed no significant differences for oocytes which cleaved normally and those which did not. Granulosa cell aromatase activity was high in all follicles, suggesting that the low periovulatory follicular fluid estradiol level is not explained by a fall in granulosa cell aromatase after hCG. High granulosa cell progesterone production and follicular fluid progesterone were consistent with advanced granulosa cell luteinization. Oocytes undergoing polyspermic activation were from larger follicles with elevated follicular fluid progesterone levels, suggesting that follicular size and follicular fluid progesterone are correlated with "over-ripeness" and polyspermy. No simple relationship exists between oocyte function and the present indices of granulosa cell steroid metabolism.

Adult↗
PubMedDate not supplied

Demonstration of avian influenza-A virus in Iran by immunodiffusion technique.

A total of 1000 chicken serum samples (CSS) and 235 turkey serum samples (TSS) were tested by an immunodiffusion procedure against soluble antigen (S-antigen) prepared from avian influenza-A virus (AIAV), T/Calif/5142/66. None of the CSS tested developed any precipitin line, whereas 8.9% of the TSS tested developed well-defined precipitin lines against S-antigen. This observation confirmed the presence of AIAV in Iran.

Animals↗
PubMedDate not supplied

Organisation of a local revision course for postgraduate examinations.

Revision courses for postgraduate examinations are usually held at central teaching hospitals. The ingredients for these courses, however, are available at most local hospitals. This article describes the practicalities of organising a successful local revision course for postgraduate examinations.

Clinical Competence↗