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Biomedical subjects

A Amar

Publications and source records attributed to A Amar.

At least 109 records · Page 6Linked to original sources
PubMed1979

Binding of lectins to membranes of mycoplasmas from aging cultures.

The binding of iodinated concanavalin A (Con A) and Ricinus communis agglutinin (RCA) to intact cells and isolated membranes of Acholeplasma laidlawii, Mycoplasma hominis and Mycoplasma capricolum decreased with the progression of the culture from the mid- to the late-logarithmic phase of growth. The binding of the lectins to Acholeplasma laidlawii membranes had no significant effect on membrane fluidity, as assessed by electron-paramagnetic resonance spectroscopy of spin-labelled fatty acids, and had no effect on several membrane-associated enzymic activities. Temperature affected the binding of Con A and RCA in an opposite manner: the binding of Con A increased, whereas that of RCA decreased, on raising the temperature from 4 degrees C to 37 degrees C. No significant difference in lectin binding was found between oleate- and elaidate-enriched membranes at low temperatures where the former was in the liquid-crystalline state and the latter in the gel state, suggesting that membranes fluidity does not influence the binding of Con A and RCA to Acholeplasma laidlawii membranes.

Acholeplasma laidlawii↗
PubMed1976

Characterization of the mycoplasma membrane proteins. VI. Composition and disposition of proteins in membranes from aging Mycoplasma hominis cultures.

Membranes of Mycoplasma hominis cells from cultures progressing from the mid to the end of the logarithmic phase of growth became richer in protein, poorer in phospholipids and cholesterol, heavier in density, and more viscous as determined by EPR. The membrane-bound ATPase activity declined steeply. Electrophoretic analysis failed to show marked changes in membrane protein composition on aging, apart from an increase in the staining intensity of one protein band (Mr approximately 130 000) concomitant with a decrease in the staining intensity of several minor protein bands of high molecular weight. To test for possible changes in the disposition of the various membrane proteins on aging of cultures, a comparison was made of the susceptibility of membrane proteins of intact cells and isolated membranes to trypsinization and lactoperoxidase-mediated iodination. The iodination values and the percent of membrane protein released by trypsinization of intact cells were similar in cells from cultures of different ages, indicating no significant changes in the organization of the proteins on the outer surface. On the other hand, trypsinization and iodination of isolated membranes were found to be most markedly affected by the culture age, indicating significant changes in the organization of the proteins on the inner membrane surface. Thus, the iodination values of isolated membranes decreased by almost two fold, while the percentage of protein released from the membrane by trypsin increased from 28% to 50% during the experimental period. It is suggested that aging in M. hominis cultures is accompanied by a continuous increase in the packing density of the protein molecules on the inner surface of the cell membrane.

Bacterial Proteins↗
PubMedDate not supplied

Donor lymphocyte infusions to displace residual host hematopoietic cells after allogeneic bone marrow transplantation for beta-thalassemia major.

PURPOSE: Donor lymphocyte infusion (DLI) was used to reverse relapse after allogeneic bone marrow transplantation (BMT) in a patient with beta-thalassemia major. PATIENTS AND METHODS: The patient with unstable mixed chimerism after BMT was treated with graded increments of donor lymphocytes (10(5) T cells/kg to 5 x 10(7) T cells/kg) to displace residual hematopoietic host cells. RESULTS: DLI resulted in complete donor-derived reconstitution of the hematopoietic compartment. The patient developed mild graft-versus-host disease (GVHD) that could be controlled by steroid treatment. CONCLUSIONS: This case report shows that DLI can effectively eradicate host stem cells in mixed chimeras after BMT in nonmalignant hematopoietic diseases.

Bone Marrow Transplantation↗
PubMedDate not supplied

[Clinical and epidemiological characteristics of squamous cell carcinoma of the oral cavity in women].

BACKGROUND: Squamous cell carcinoma (SCC) of the oral cavity occurs mainly in the male population. The objective of the study is to identify the main clinical and epidemiological differences of the oral SCC between men and women. METHODS: Retrospective analysis of the charts of 228 cases of SCC of the oral cavity in women treated at the Head & Neck Surgery Service, Heliopolis Hospital, São Paulo, Brazil from 1977 to 1996. The clinical and epidemiological characteristics of these cases were compared with those of 849 male patients. RESULTS: The mean age of women was 60.7 years (ranging 2 to 100 years) and in the male group was 55.6 years (p<0.00001). In cases where the alcohol intake and tobacco use were absent, the tumors ocurred in older patients. The isolated tobacco use didn't affect the distribuction by age but for the alcohol intake (alone or combined with tobacco) the patients were younger. On the alcohol intake, 71% of the women and 8% of the man used no alcohol. The most common sites of tumors were tongue and floor of the mouth but in the women group the incidence of tumors in these sites were 43% compared with 61% in the men. CONCLUSIONS: The highest incidence of SCC the of oral cavity occurs later in women, than in men. This could be explained by a lesser exposure to alcohol and tobacco in women. Other factors seem to be involved in this issue.

Adolescent↗
PubMedDate not supplied

[Factitious lithiasis: Case report from Western Algeria].

A 19-year-old woman with recurrent lithiasis was admitted to the urology department for renal colic. Although radiologic examinations and laboratory tests were negative, the patient regularly brought into consultations small "stones", resembling gravel, that she said had been spontaneously expelled. These 42 samples were the object of a preliminary morphological analysis under a binocular magnifier to detect their particulate components. A non-metabolic origin was suspected from the organoleptic characteristics of their surfaces and sections. In view of the diversity of the materials of these apparently false calculi, methods of precise physical analysis were necessary to ascertain their exact origin and thereby confirm the diagnosis of factitious lithiasis. The use of two methods of physical analysis, infrared spectrophotometry and x-ray diffraction, enabled us to determine their exact chemical and mineralogical composition. The samples claimed to be of urinary origin actually consisted of exogenous products of various compositions. Some samples were made of pure calcite, others of mixed calcite and silicates. Moreover several samples of the patient's first morning urine showed no correlation between the nature of the crystalluria and the composition of these stones. These tests made it possible to direct the clinician towards useful complementary investigations. This strange case represents 0.1% of the urinary calculi analysed in Western Algeria.

Adult↗