Pilar Lardelli

Mn2+-activated aspartat aminopeptidase activity, subcellular localization in young and adult rat brain

The levels of soluble and membrane-bound aminopeptidase activities were assayed in subcellular fractions from young (4 weeks old) and adult (20 weeks old) rat brains, using Asp-2-naphthylamide as substrate. The young rats showed the highest soluble and membrane-bound levels of activity in the microsomal fraction but no differences among fractions were found at 20 weeks of age. The membrane-bound activity was significantly higher than the soluble one in all subcellular fractions of young rats. Soluble activity of the homogenate and the mitochondrial fraction was significantly increased in adult animals when compared to that of younger ones.

Daily Rhythm of Aspartate Aminopeptidase Activity in the Retina, Pineal Gland and Occipital Cortex of the Rat

The levels of specific soluble aspartyl aminopeptidase activity were assayed in retina, occipital cortex, anterior pituitary, posterior pituitary, pineal gland and serum of adult male rats, using Asp-2-naphthylamide as substrate, in a 12:12 h light:dark cycle (7-19 h light). Significant diurnal variations appeared in retina, pineal gland, occipital cortex and serum. In addition, different patterns of diurnal variation of the enzymatic activity were observed in the tissues analyzed. A regular increase of the activity was noticed at the end of the dark period in all the tissues as a common feature, except in serum, in which the enzymatic activity reached a peak in the middle of the light period, decreasing progressively during the dark hours. After the last hours of darkness, the pattern of variation in the activity differed in each tissue. These diurnal variations in aspartyl aminopeptidase activity could reflect the functional status of its putative endogenous substrates, such as angiotensin II, and it may also suggest the existence of differential regulatory mechanisms associated with each location.

Mononuclear Cell Subsets in IgM Mesangial Proliferative Glomerulonephritis

Glomerular and interstitial leukocyte subpopulations were analyzed in renal biopsies from 18 patients with IgM mesangial proliferative glomerulonephritis (IgM MPGN), 19 patients with minimal change nephrotic syndrome (MC) and 10 patients with immune-negative mesangial proliferative glomerulonephritis (IN MPGN), by immunoperoxidase techniques with monoclonal antibodies. Mesangial cell proliferation was strongly correlated with absolute numbers of intraglomerular T lymphocytes (r = 0.71; p < 0.01) in IgM MPGN, but not in MC or IN MPGN. Significant differences were found in the numbers of macrophages, CD4- and CD8-positive glomerular cells (Students t test p < 0.01, 0.05 and 0.01, respectively) in IgM MPGN, but not in MC or IN MPGN. The numbers of CD45-, CD3- and CD8-positive cells also differed in each patient group (ANOVA p < 0.01, 0.05 and 0.05, respectively), the greatest and smallest values appearing in IgM MPGN and MC, respectively. Multiple regression test showed initial proteinuria values in IgM MPGN to be closely dependent on the density of neutrophils, macrophages, T and B lymphocytes and CD4 cell inflammatory infiltrates (r2 = 0.92; p < 0.01). At the end of the follow-up, proteinuria in IgM MPGN, but not in MC or IN MPGN, was dependent on T cell infiltrate (r2 = 0.97; p < 0.01). Our findings suggest that proteinuria in IgM MPGN results from local mesangial damage rather than from the effects of a soluble circulating factor, as has been proposed for MC. The clinical and immunohistochemical differences observed between these two processes support the notion that they should be considered as separate entities.

Correlative Detection of Human Immunodeficiency Virus (HIV) Antigen p24 and Epstein-Barr Virus DNA In Vitro : Clinical Influence on HIV Infection

The existence of molecular transactivations between EBV and HIV‐1, as well as reactivations of EBV latent infections in AIDS patients, have been recently documented. In order to shed more light on the putative association between EBV and HIV, and its role in the evolution to AIDS, we have determined simultaneously p24 protein and EBV DNA in culture supernatants of peripheral blood mononuclear cells from 47 individuals suspected of having HIV infection. The results of the in vitro assays were correlated with the clinical stage of the individuals and their serologic status to EBV. Statistical analysis showed a concordance between HIV infection and in vitro detection of EBV DNA (P < 0.002); particularly, a strong correlation between the presence of EBV DNA and p24 in culture was observed (P < 0.001). These results are consistent with the occurrence of viral interactions, manifested in vitro. However, in our series, the appearance of EBV DNA in culture was not concomitant with an elevation of anti‐VCA IgG titers, anti‐EA titers or the development of symptomatology, suggestive of a reactivation of a latent EBV infection or a progression of HIV infection. Therefore we conclude that, although interaction between both viruses may take place at the molecular level, there is no clear evidence of the repercussion that this event may have on the clinical course of HIV infection.