Cerebral toxoplasmosis is the most common cerebral focal lesion in AIDS and still accounts for high morbidity and mortality in Brazil. Its occurrence is more frequent in patients with low CD4⁺T-cell counts. It is directly related to the prevalence of anti-Toxoplasma gondiiantibodies in the population. Therefore, it is important to evaluate sensitive, less invasive, and rapid diagnostic tests. We evaluated the value of PCR using peripheral blood samples on the diagnosis of cerebral toxoplasmosis and whether its association with immunological assays can contribute to a timely diagnosis. We prospectively analyzed blood samples from 192 AIDS patients divided into two groups. The first group was composed of samples from 64 patients with cerebral toxoplasmosis diagnosed by clinical and radiological features. The second group was composed of samples from 128 patients with other opportunistic diseases. Blood collection from patients with cerebral toxoplasmosis was done before or on the third day of anti-toxoplasma therapy. PCR forT. gondii, indirect immunofluorescence, enzyme-linked immunosorbent assay, and an avidity test for toxoplasmosis were performed on all samples. The PCR sensitivity and specificity for diagnosis of cerebral toxoplasmosis in blood were 80% and 98%, respectively. Patients with cerebral toxoplasmosis (89%) presented higher titers of anti-T. gondiiIgG antibodies than patients with other diseases (57%) (P< 0.001). These findings suggest the clinical value of the use of both PCR and high titers of anti-T. gondiiIgG antibodies for the diagnosis of cerebral toxoplasmosis. This strategy may prevent more invasive approaches.

Highly active antiretroviral therapy has decreased the incidence of opportunistic infections in the central nervous system in AIDS patients. However, neurological abnormalities still remain important causes of mortality and morbidity in developing countries. In Brazil, cerebral toxoplasmosis is the most common cerebral mass lesion in AIDS patients. For these reasons, early, inexpensive, and sensitive diagnostic tests must be evaluated. The aim of this study was to evaluate PCR, using cerebrospinal fluid (CSF) samples to detectToxoplasma gondiiDNA, and to determine if the association of PCR with immunological assays can contribute to a timely diagnosis. We studied two sample groups. First, we analyzed stored CSF samples from 29 newborns and from 39 adults with AIDS without a definitive diagnosis of toxoplasmosis. The goal of this step was to standardize the methodology with a simple and economical procedure to recover theT. gondiiDNA. Next, we prospectively evaluated CSF samples from 12 AIDS patients with a first episode of cerebral toxoplasmosis and 18 AIDS patients with other neurological opportunistic diseases and without previous cerebral toxoplasmosis. In all PCR samples, an indirect immunofluorescent assay and an enzyme-linked immunosorbent assay were performed. Samples from all patients with cerebral toxoplasmosis presented positive PCR results (sensitivity, 100%), and a sample from one of the 18 AIDS patients with other neurological diseases also presented positive PCR results (specificity, 94.4%). These findings suggest the clinical utility of PCR in the diagnosis of cerebral toxoplasmosis in developing countries.

Bioactive molecules stored in dentin, such as transforming growth factor beta1 (TGF-b1), may be involved in the signaling events related to dental tissue repair. The authors conducted an in vitro evaluation of the amount of TGF-b1 released from dentin slices after treatment with 10% ethylenediaminetetraacetic acid (EDTA), 2.5% sodium hypochlorite (NaOCl) or phosphate-buffered saline (PBS), and the effect of this growth factor on stem cell migration from human exfoliated deciduous teeth (SHED). Sixty 1-mm-thick tooth slices were prepared with or without the predentin layer, and treated with either 10% EDTA for 1 minute, 2.5% NaOCl for 5 days or kept in PBS. Tooth slice conditioned media were prepared and used for TGF-b1 ELISA and migration assays. Culture medium with different concentrations of recombinant human TGF-b1 (0.5, 1.0, 5.0 or 10.0 ng/mL) was also tested by migration assay. The data were evaluated by ANOVA and Tukey's test. Optical density values corresponding to media conditioned by tooth slices either containing or not containing the predentin layer and treated with 10% EDTA were statistically greater than the other groups and close to 1 ng/mL. Increased rates of migration toward media conditioned by tooth slices containing the predentin layer and treated with PBS, 10% EDTA or 2.5% NaOCl were observed. Recombinant human TGF-b1 also stimulated migration of SHED, irrespective of the concentration used. EDTA may be considered an effective extractant of TGF-b1 from the dentin matrix. However, it does not impact SHED migration, suggesting that other components may account for the cell migration.