Ami Klein

The effect of HIV-1 infection on the lipid fatty acid content in the membrane of cultured lymphocytes

Elevations in the levels of unsaturated fatty acids (FAs) in membrane lipids lead to an increase in cell membrane fluidity and may also be involved in cell fusion and death through the loss of normal membrane function and integrity. Since the infection of susceptible cells with HIV leads to cell fusion and subsequent loss of viability, the present study was undertaken to see whether HIV infection can alter the relative content of unsaturated FAs in the host cell membrane and to determine whether this change correlates with cell death. Peripheral lymphocytes (PBLs) of a healthy donor and two CD4+ cell lines were chosen: MT-4, which is killed following HIV infection, with significant cell death being observed 5 days postinfection, and H9 which is not killed. Measurements of FA content of the two cell lines and PBLs, either before or at 6, 24, and 48 h after infection, showed a significant rise in the concentration of unsaturated FAs followed by a drop in the concentration of saturated FAs in the MT-4 cell line. With regard to the H9 cell line similar results were obtained at 6 h from infection. However, at 24 and 48 h the concentrations of saturated FAs returned to preinfection levels while the concentrations of unsaturated FAs dropped to levels even lower than those obtained at zero time. No significant changes in FA composition were found with PBLs.

A difference between human B and T lymphocytes regarding their capacity to metabolize cortisol.

Abstract Since T lymphocytes are more sensitive than B lymphocytes to Cortisol treatment, the cortisol metabolism in these two cell groups was measured and compared. Known concentrations of human T and B lymphocytes were incubated with [1,2- 3 H]-cortisol and the products isolated by thin layer chromatography and paper chromatography. Cells from the B lymphocytes group were found more active than those from the T cells, whereas the distribution of the cortisol metabolites showed no significant difference between the groups. These findings suggest that the higher resistance to cortisol of B cells compared with that of T cells, are due to the relatively higher metabolism of cortisol by B lymphocytes and that this may act as defence mechanism against the hormone.

Delta-T-lymphocytosis in a patient with thymoma.

Background. Malignant thymoma is composed of neoplastic epithelial cells and small lymphocytes. Rarely, patients also may have peripheral T‐lymphocytosis. These lymphocytes have been considered nonneoplastic because of their microscopic appearance and immunophenotype, as well as gene rearrangement studies.

Inhibition of 11β-hydroxylation of deoxycorticosterone in mitochondria of bovine adrenal cortex

Abstract The kinetics of inhibition of 11β-hydroxylation of deoxycorticosterone in bovine mitochondria was determined for dehydroepiandrosterone (DHA) and metyrapone. Both compounds inhibited competitively the 11β-hydroxylase. The Michaelis-Menten constant of the reaction using intact mitochondria was evaluated at K m = 102 μmol. The K i for DHA was found to be 72 × 10 -5 mol and that for metyrapone K i = 28 × 10 -5 mol.