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Biomedical subjects

M C Silva

Publications and source records attributed to M C Silva.

At least 55 records · Page 3Linked to original sources
PubMed1996

HTLV-I/II as a common etiology of myelopathies in Bahia, Brazil.

Infection by human T-cell lymphotrophic virus type I (HTLV-I) is associated with a myelopathy known as tropical spastic paraparesis (TSP). The prevalence of HTLV-I infection was found to be high in a pilot study in Bahia, Brazil. In the present study, among patients with myelopathy of unclear etiology, 27% (17/62) were immunoblot reactive to HTLV-I/II (serum and CSF), but none of 40 consecutive patients seen at the neurological clinic and having a well-established neurological diagnosis had detectable antibodies against those viruses (discrimination between HTLV-I and HTLV-II was not possible with the tests we used). The clinical syndrome of typical TSP with upper limb hyperreflexia was found to be a significant feature among the HTLV-I/II-seropositive patients compared to seronegative individuals. The 17 HTLV-I/II-reactive individuals had negative tests for syphilis, toxoplasmosis and schistosomiasis. TSP was also associated with female gender (P = 0.001). We conclude that TSP is strongly associated with HTLV-I/II infection in women in Bahia.

Adult↗
PubMed1995

From Carper's patterns of knowing to ways of being: an ontological philosophical shift in nursing.

Carper's 1978 article in the premiere issue of Advances in Nursing Science encouraged nurses to consider four fundamental patterns of knowing. Through illustrations from literature and the performing arts, the authors address Carper's patterns of knowing in the context of an emerging philosophical shift. First, they critique the major strengths and limitations of the article. Next, they explore an emerging philosophical shift in nursing from Carper's epistemological focus to ontological reflections on ways of being. Finally, they discuss the significance of the emerging philosophical shift and the ways of being for the science-art of nursing.

Cognition↗
PubMed1995

Effect of cellular physiology on PCR amplification efficiency.

Culture conditions, and other variables that modulate a cell's physiology, can bias a polymerase chain reaction (PCR) amplification against generating a representative population profile. Two Pseudomonas putida nahR alleles were constructed in pUC19 that differ solely in a 31-bp internal segment whose sequence has been inverted. After PCR amplification, the products could be distinguished on the basis of a change in a unique restriction site. When an Escherichia coli strain carrying one nahR allele is submitted to different growth conditions, the consequences of such variations on the relative PCR amplification of whole cells can be ascertained through coamplification with a strain carrying the other allele and subsequent restriction analysis. Cells in stationary phase displayed improved amplifiability while cells grown at 42 degrees C were equally amplifiable as compared to cells grown at 37 degrees C. However, sublethal levels of tetracycline or growth in minimal medium made the PCR target in these cells relatively less amplifiable. When cells are completely lysed and the plasmid DNA is purified beforehand, the coamplification bias is eliminated. These results suggest that mixed populations containing cells in different physiological states may not be representatively amplified by PCR unless a DNA extraction step is included.

Alleles↗
PubMed1994

Quantitative cell lysis of indigenous microorganisms and rapid extraction of microbial DNA from sediment.

This study reports improvements in two of the key steps, lysis of indigenous cells and DNA purification, required for achieving a rapid nonselective protocol for extracting nucleic acids directly from sodium dodecyl sulfate (SDS)-treated sediment rich in organic matter. Incorporation of bead-mill homogenization into the DNA extraction procedure doubled the densitometrically determined DNA yield (11.8 micrograms of DNA.g [dry weight] of sediment-1) relative to incorporation of three cycles of freezing and thawing (5.2 micrograms of DNA.g [dry weight] of sediment-1). The improved DNA extraction efficiency was attributed to increased cell lysis, measured by viable counts of sediment microorganisms which showed that 2 and 8%, respectively, survived the bead-mill homogenization and freeze-thaw procedures. Corresponding measurements of suspensions of viable Bacillus endospores demonstrated that 2 and 94% of the initial number survived. Conventional, laser scanning epifluorescence phase-contrast, and differential interference-contrast microscopy revealed that small coccoid bacterial cells (1.2 to 0.3 micron long) were left intact after combined SDS and bead-mill homogenization of sediment samples. Estimates of the residual fraction of the fluorescently stained cell numbers indicated that 6% (2.2 x 10(8) cells.g [dry weight] of sediment-1) of the original population (3.8 x 10(9) cells.g [dry weight] of sediment-1) remained after treatment with SDS and bead-mill homogenization. Thus, lysis of total cells was less efficient than that of cells which could be cultured. The extracted DNA was used to successfully amplify nahR, the regulatory gene for naphthalene catabolism in Pseudomonas putida G7, by PCR.(ABSTRACT TRUNCATED AT 250 WORDS)

Bacteriolysis↗
PubMed1994

The heterogeneity of the beta s cluster haplotypes in Brazil.

The beta s cluster haplotypes were determined for 74 Brazilian patients with sickle cell anemia from three cities separated by 1,400 to 2,300 km. The cities are representative of the regions which have the largest Black populations of the country. All 138 chromosomes with typical haplotypes had one of the three most common African haplotypes. No example of the Asian or of the Cameroon haplotypes was found. The Bantu haplotype predominates in all three regions (54.8 to 73.1%), followed by the Benin haplotype (25.4 to 45.2%) and a small number of cases with the Senegal haplotype (0 to 6.9%). The mean prevalence of the Bantu haplotype of 65.9% agrees closely with historical data which indicate that 70% of the African slaves brought to Brazil originated from regions of Bantu populations.

Anemia, Sickle Cell↗
PubMed1994

[Cryoglobulins in rheumatoid arthritis: exhaustive detection, immunochemical findings and clinical expression].

Cryoglobulins were measured in 29 patients (24 female, age 53.8 +/- 9.8 years) with rheumatoid arthritis (70% active). The cryoprecipitate was isolated, characterized and quantified. Cryoglobulinemia, always polyclonal or type III, was found in 83% of patients. The most frequent immunochemical isotypes found were IgG and A. Acrocyanosis was found in 50% and Raynaud phenomenon in 32% of patients with cryoglobulinemia. It is concluded that exhaustive detection of cryoglobulinemia in rheumatoid arthritis demonstrated a higher frequency than previously reported an is important for understanding pathogenesis of the disease.

Adult↗
PubMed1993

Body weight gain and hippocampal volumes of rats exposed neonatally to psychostimulants.

There is increasing evidence that early exposure to psychostimulants exerts long-lasting effects on the central nervous system. Yet, analysis of the body weight gain and volumetric determinations of brain areas have not been performed by comparing the effects of neonatal exposure to cocaine and amphetamine. Male (Wistar) rats were given cocaine hydrochloride (15 mg/kg body weight/day), D-amphetamine sulphate (25 mg/kg body weight/day) or saline, s.c., twice daily, from postnatal day (PND) 1 to 30. The experimental design used random permuted blocks of 4 males per litter -9 litters for body weight gain evolution and 9 for the analysis of body, brain and cerebellum at PND30. Volumes of the hippocampal formation were calculated in horizontal serial sections of celloidin embedded material from 6 animals per group. The analysis of body weight gain evolution was performed using discriminant functions and allowed the separation of the amphetamine group from the remainder and the control from the psychostimulants group; weight gain in PND 24-30 period presented the highest discriminating power. The mean volume of the hippocampal formation was lower in the psychostimulants group, and the differences were significant in the molecular layer of the dentate gyrus of cocaine and amphetamine exposed animals when compared with the controls.(ABSTRACT TRUNCATED AT 250 WORDS)

Amphetamine↗
PubMed1993

Changes in the retinal ganglion cell layer and optic nerve of rats exposed neonatally to cocaine.

The effects of neonatal exposure to cocaine upon the structure of the visual system are poorly understood despite the evidence of eye abnormalities in infants exposed in utero to cocaine. We previously demonstrated alterations in the optic nerve of rats exposed neonatally to cocaine, although no changes were detected in the number of its axons. This study was undertaken to investigate the retinal ganglion cell layer and the size distribution of the optic axons, in an attempt to assess further changes in the visual pathways. Groups of rats (Wistar strain) were given subcutaneous injections of cocaine hydrochloride (15 mg kg-1 body weight day-1) divided into two daily doses, from the day following birth until postnatal day 30 Controls were given subcutaneous saline throughout the same experimental period. Per group, five animals from three different litters were evaluated morphometrically. Following perfusion with aldehydes, samples from the median ventral and dorsal parts of the retina and the optic nerves were processed for electron microscopy. Morphometric techniques at light and electron microscopic levels allowed us to determine the following. (a) In the optic nerve: (1) frequency size-distribution of myelinated nerve fibres; and (2) number of myelin sheaths per fibre. (b) In the retina: (1) thickness of the layers; (2) frequency size-distribution of ganglion layer neurons; (3) mean cell nuclear size; and (4) packing density of ganglion cell layer neurons.(ABSTRACT TRUNCATED AT 250 WORDS)

Animals↗
PubMed1993

Prognostic significance of aromatase and estrone sulfatase enzymes in human breast cancer.

The aromatase and estrone sulfatase enzymes are important sources of local synthesis of biologically active estrogens in human breast cancer. Significant intratumoral aromatase activity was detected in 91/145 (63%) of tumors and estrone sulfatase was detected in 93/104 (89%) of tumors. There was no relationship between aromatase activity and tumor size, site, nodal status, menopausal status or estrogen receptor status. There was a significant correlation between the aromatase activity and histological grade, with an excess of aromatase-positive in the high grade tumors (P = 0.03). There was a marginally inverse correlation between the aromatase activity and time to relapse (P < 0.1), a significant correlation between aromatase activity and survival after relapse (P < 0.05) but not with overall survival (P > 0.1). Intratumoral estrone sulfatase activity was not significantly correlated to any putative prognostic factors, nor with time to relapse nor overall survival time.

Aromatase↗