Congenital cytomegalovirus infection in a neonatal intensive care unit in brazil evaluated by PCR and association with perinatal aspects

Cytomegalovirus (CMV) infection is the most common congenital infection, affecting 0.4% to 2.3% newborns. Most of them are asymptomatic at birth, but later 10% develop handicaps, mainly neurological disturbances. Our aim was to determine the prevalence of CMV shed in urine of newborns from a neonatal intensive care unit using the polymerase chain reaction (PCR) and correlate positive cases to some perinatal aspects. Urine samples obtained at first week of life were processed according to a PCR protocol. Perinatal data were collected retrospectively from medical records. Twenty of the 292 cases (6.8%) were CMV-DNA positive. There was no statistical difference between newborns with and without CMV congenital infection concerning birth weight (p=0.11), gestational age (p=0.11), Apgar scores in the first and fifth minutes of life (p=0.99 and 0. 16), mother's age (p=0.67) and gestational history. Moreover, CMV congenital infection was neither related to gender (p=0.55) nor to low weight (<2,500 g) at birth (p=0.13). This high prevalence of CMV congenital infection (6.8%) could be due to the high sensitivity of PCR technique, the low socioeconomic level of studied population or the severe clinical status of these newborns.

Monitoring human cytomegalovirus viral load in peripheral blood leukocytes of renal transplant recipients by a simple limiting dilution-PCR assay

To assess the clinical relevance of a semi-quantitative measurement of human cytomegalovirus (HCMV) DNA in renal transplant recipients within the typical clinical context of a developing country where virtually 100% of both receptors and donors are seropositive for this virus, we have undertaken HCMV DNA quantification using a simple, semi-quantitative, limiting dilution polymerase chain reaction (PCR). We evaluated this assay prospectively in 52 renal transplant patients from whom a total of 495 serial blood samples were collected. The samples scored HCMV positive by qualitative PCR had the levels of HCMV DNA determined by end-point dilution-PCR. All patients were HCMV DNA positive during the monitoring period and a diagnosis of symptomatic infection was made for 4 of 52 patients. In symptomatic patients the geometric mean of the highest level of HCMV DNAemia was 152,000 copies per 10(6) leukocytes, while for the asymptomatic group this value was 12,050. Symptomatic patients showed high, protracted HCMV DNA levels, whereas asymptomatic patients demonstrated intermittent low or moderate levels. Using a cut-off value of 100,000 copies per 10(6) leukocytes, the limiting dilution assay had sensitivity of 100%, specificity of 92%, a positive predictive value of 43% and a negative predictive value of 100% for HCMV disease. In this patient group, there was universal HCMV infection but relatively infrequent symptomatic HCMV disease. The two patient groups were readily distinguished by monitoring with the limiting dilution assay, an extremely simple technology immediately applicable in any clinical laboratory with PCR capability.

Utilization of microsatellites for the analysis of genomic alterations in colorectal cancers in Brazil

Two different pathogenetic mechanisms are proposed for colorectal cancers. One, the so-called "classic pathway", is the most common and depends on multiple additive mutational events (germline and/or somatic) in tumor suppressor genes and oncogenes, frequently involving chromosomal deletions in key genomic regions. Methodologically this pathway is recognizable by the phenomenon of loss of heterozygosity. On the other hand, the "mutator pathway" depends on early mutational loss of the mismatch repair system (germline and/or somatic) leading to accelerated accumulation of gene mutations in critical target genes and progression to malignancy. Methodologically this second pathway is recognizable by the phenomenon of microsatellite instability. The distinction between these pathways seems to be more than academic since there is evidence that the tumors emerging from the mutator pathway have a better prognosis. We report here a very simple methodology based on a set of tri-, tetra- and pentanucleotide repeat microsatellites allowing the simultaneous study of microsatellite instability and loss of heterozygosity which could allocate 70% of the colorectal tumors to the classic or the mutator pathway. The ease of execution of the methodology makes it suitable for routine clinical typing.

Quantitation and karyometry of cerebral neuroglia and endothelial cells in liver cirrhosis and in the hepatosplenic schistosomiasis mansoni

A morphological, karyometric, and quantitative study of cerebral neuroglia and endothelial cells of blood capillaries was done in cirrhotic and in hepatosplenic schistosomotic human autopsied cases. Cluster analysis applied to them revealed three subgroups (cirrhosis and schistosomiasis polar groups and one intermediate). The comparison of these three groups with a control revealed increased numbers of astrocytes, oligodendrocytes and endothelial cells, but no nuclear enlargement in the schistosomiasis group; the cirrhosis group exhibited a pronounced nuclear enlargement of both astrocyte and oligodendrocytes but no increase in cell numbers. The intermediate group, which encompasses the majority of pathological cases, is heterogeneous but on average behave as the cirrhosis group in that nuclear enlargement, but no increase in cell numbers, was noted. Such changes could represent a response of the nervous system to the metabolic disturbances present in hepatic and/or portal-systemic encephalopathy. There was a positive correlation between glial and endothelial cell numbers in cerebral cortex, suggesting a functional relationship between the glial cells and the capillary bed. This study points out the importance of clustering the cases, because the physiopathological status of individuals belonging to the same nosological condition can be different. Comparisons considering this aspect should be useful in understanding the progression of the pathological process.

The significance of paired astrocyte nuclei in normal human nervous tissue

A quantitative study of astrocytes was carried out in 80 microscopic fields and the number of paired nuclei in 100 consecutive astrocytes of the temporo-occipital gyrus cortex was determined in 13 patients with no cerebral or liver disease. No significant correlation was found between astrocyte number and the percentage of paired nuclei. When studies on astrocytes in hepatic encephalopathy, liver cirrhosis and hepatosplenic schistosomiasis are taken into consideration it is suggested that these cells are in continuous variable renewal in normal adult human nervous tissue, as occurs in other animal species.