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Biomedical subjects

A E Silva

Publications and source records attributed to A E Silva.

At least 19 recordsLinked to original sources
PubMed2003

Echocardiographic evaluation of fetal hydrothorax: the effusion ratio as a diagnostic tool.

OBJECTIVE: Fetal hydrothorax may lead to hydrops and is associated with mortality as high as 50%. The objective of this study was to define the pathophysiology of fetal hydrothorax and its relation to hydrops. METHODS: Measurements from echocardiograms of 33 fetuses diagnosed with hydrothorax were made, and included diameters of the thorax, heart, inferior vena cava, right ventricle (RV), left ventricle (LV) and aortic and pulmonary valves. Doppler-derived velocities were measured in the aorta and pulmonary artery just above the aortic and pulmonary valves. The ratio of the area of the effusion to the area of the thorax (effusion ratio) was calculated. Variables were converted into Z-scores from regression equations based on normal data. Features of fetuses with and without hydrops were compared. RESULTS: Higher effusion ratios were noted in hydropic versus non-hydropic fetuses. Compared to a normal population, study subjects had smaller dimensions of LV, RV and aortic and pulmonary valves. They also had higher pulmonary artery peak velocities. The comparison between non-hydropic and hydropic fetuses revealed lower values for LV and pulmonary valve dimensions, and peak aortic velocity in hydropic fetuses. The severity of LV compression correlated significantly with effusion ratio. CONCLUSION: Fetal hydrothorax is accompanied by compression of the cardiac structures, resulting in altered cardiac hemodynamics. Echocardiographic assessment, including the measurement of effusion ratio, may be a useful tool in guiding fetal therapy.

Blood Flow Velocity↗
PubMed2003

Renal artery aneurysm in hand-assisted laparoscopic donor nephrectomy: case report.

We report a living donor who underwent laparoscopic nephrectomy using a hand-assisted device (HALD). At preoperative arteriography the donor showed a renal artery aneurysm. The patient was a 37-year-old female, 166 cm height, white, weighing 87 kg, HLA identical to the recipient. HALD was indicated due to the better visualization of renal pedicle and greater security in an obese patient. Renal artery aneurysm is a rare condition, with many possible complications. The method proved to be adequate and safe for donor nephrectomy, despite a renal artery aneurysm.

Aneurysm↗
PubMed2000

Influence of glial growth factor and Schwann cells in a bioresorbable guidance channel on peripheral nerve regeneration.

Using an established rat peripheral nerve regeneration model, we investigated the role of glial growth factor (GGF) in nerve regeneration in combination with a novel bioresorbable poly(lactic-co-glycolic) acid (PLGA) guide in vivo. Schwann cells, established from a 1-cm segment of excised rat sciatic nerve, were isolated and seeded onto nerve guides with or without GGF (n = 24/group). Living nerve guides were re-established in these animals, and nerve regeneration was assessed over a period of 12 weeks. Histological studies revealed a reduction in the total axon count and the number of myelinated axons in the presence of exogenously added Schwann cells compared to saline controls. In contrast, the addition of GGF alone enhanced the total number of axons and significantly increased the number of blood vessels. Although combining GGF with Schwann cells negated the enhanced numbers of axons and blood vessels seen with GGF alone, this combination resulted in the highest myelination index and the fastest conduction velocities recorded. The PLGA guide material did not trigger any histologically detectable host response and was permissive for nerve regeneration in this animal model. The results from this study demonstrate the potential utility of this guide in vivo and establish a promotional role for GGF in nerve regeneration.

Animals↗
PubMed2000

Developing porosity of poly(propylene glycol-co-fumaric acid) bone graft substitutes and the effect on osteointegration: a preliminary histology study in rats.

Bioresorbable bone graft substitutes could eliminate disadvantages associated with the use of autografts, allografts and other synthetic materials. We investigated a bioresorbable bone graft substitute made from the unsaturated polyester poly(propylene fumarate) which is crosslinked in the presence of soluble and insoluble calcium filler salts. This compact bone graft substitute material develops porosity in vivo by leaching of the soluble filler salts. In attempt to develop materials whose in vivo porosity can be designed such that implant degradation would occur at a rate that remains supportive of the overall structural integrity of the repairing defect site, we studied the early tissue response upon implantation in a bony defect. Three grout formulations of varying solubilities using slightly soluble hydroxyapatite (HA) and soluble calcium acetate (CA) were evaluated in 3 mm holes made in the anteromedial tibial metaphysis of 200 g Sprague Dawley rats (n = 16 per formulation for a total of 48 animals). Grout formulations cured in situ. Animals from each formulation were sacrificed in groups of 8 at 4 days and 3 weeks postoperatively. Histologic analysis of the healing process revealed improved in vivo osteointegration of bone graft substitutes when a higher loading of calcium acetate was employed. All formulations maintained implant integrity and did not provoke sustained inflammatory responses. This study suggested that the presence of a soluble salt permits in vivo development of porosity of a poly(propylene fumarate) based bone graft substitute material.

Acetates↗
PubMed2000

A prospective and randomized study using ribavirin as monotherapy for the treatment of naïve patients with chronic hepatitis C.

In order to evaluate the response to ribavirin in previously untreated patients with chronic hepatitic C, 39 patients were selected for a double-blind prospective and randomized trial, and divided into two groups: ribavirin-group (19 patients) and placebo-group (20 patients). Ribavirin was administered orally for 24 weeks (600 mg/day, followed by 1,000 mg/day and 1,200 mg/day each one for 8 weeks). After 3 months of drug administration, the patients were evaluated by measuring biochemical, virologic and histologic responses. After this phase, ribavirin was offered to the patients who had received placebo (second phase). The results showed that the patients who received ribavirin showed a higher reduction in serum alanine aminotransferase (ALT) activity than patients in the placebo group. Among the patients in the ribavirin-group, a complete biochemical response (ALT levels normalized) was observed in 3 patients (16%), and a partial response (reduction greater than 50% of the initial value of ALT activity) in 4 (21%). In the 20 patients in the placebo group, only 1 showed a partial response (5%). In the second phase of the study, among 16 patients who received ribavirin, 4 (25%) showed a complete and 5 (31%) a partial biochemical response. HCV-RNA did not become negative in any patient during the two phases. A reduction in the score of portal and lobular activity was observed in patients who received ribavirin, but statistical analysis did not identify differences. This study showed that ribavirin alone induces a biochemical response (ALT reduction) in some patients with chronic hepatitis C, which may be associated with a reduction in hepatic inflammatory activity reduction, but the changes are not sufficient to recommend initial monotherapy with ribavirin.

Administration, Oral↗
PubMed1999

Augmentation of osteoinduction with a biodegradable poly(propylene glycol-co-fumaric acid) bone graft extender. A histologic and histomorphometric study in rats.

We investigated the feasibility of enhancing the regeneration of skeletal tissues by augmenting bone grafts with a composite biodegradable bone graft extender material based on the polymer poly(propylene fumarate), PPF. The material was mixed with autograft and allograft and placed directly into a cylindrical metaphyseal defect made in the rat tibia. These formulations were compared to defects without any graft material, autografts, allografts and PPF alone. Nine animals were included in each group. Animals were sacrificed at 1 and 4 weeks postoperatively. Implantation sites were then evaluated using histologic and histomorphometric methods. Results of this study showed that defects did not heal in sham operated animals. In the experimental groups, there was early new woven bone formation in the autograft group with near complete healing of the defect at four weeks. When PPF was used alone, gradual ingrowth of new bone was seen. Mixing of the PPF bone graft extender with either allograft or autograft material resulted in enhancement of new bone formation with both allo- and autograft. However, significantly more new bone formation than in the autograft group was only seen when the PPF bone graft extender was mixed with fresh autograft. Histomorphometry corroborated these findings. Results of this study suggest that a PPF-based material may be used to increase the volume of smaller amounts of bone grafts supporting the concept of "bone graft extenders" by application of engineered biodegradable porous scaffolds.

Absorbable Implants↗
PubMed1998

Hepatitis B virus DNA in persons with isolated antibody to hepatitis B core antigen who subsequently received hepatitis B vaccine.

Serum samples from 133 persons who were positive only for antibody to hepatitis B core antigen (anti-HBc) by enzyme immunoassay (EIA) were retested for seromarkers of hepatitis B virus (HBV) by radioimmunoassay and for HBV DNA by polymerase chain reaction analysis. All persons were subsequently vaccinated with hepatitis B vaccine. HBV DNA was found in only five persons, four of whom remained positive during retesting. Most persons had a primary antibody response with three doses of hepatitis B vaccine. Evidence of HBV DNA was not detected in 96% of persons with isolated anti-HBc by EIA.

DNA, Viral↗
PubMed1996

Fulminant hepatitis in patients undergoing liver transplantation: evidence for a non-A, non-B, non-C, non-D, and non-E syndrome.

Fulminant hepatic failure (FHF) in the absence of serum markers of hepatitis A (HAV) or B (HBV) infection or another cause is called non-A, non-B (NANB) FHF. The pathogenetic role of viral infection in NANB FHF remains controversial. To better define this relationship, we studied patients who underwent orthotopic liver transplantation (OLT) for FHF. Thirty-six patients with FHF underwent transplantation between 1987 and 1992. Pre-OLT serum was available for 24 patients, 14 with NANB FHF (all female; mean age, 32 years), and 10 (3 males, 7 females; mean age, 20 years) with a defined origin for FHF who formed the control group. Sera were tested using polymerase chain reaction for HAV, HCV, HDV, and HEV RNA and HBV DNA, and also serologically for antibodies to these viruses. In the NANB group, pre-OLT serum was negative for all viruses tested. Four patients in the control group had HBV serologically, 2 with HBV DNA in serum. One of these 4 also had hepatitis C and one hepatitis D infection. There was no difference in intensive care unit or hospital stay between the groups. The only significant difference in laboratory data was for peak creatinine pre-OLT (0.94 mg/dL in NANB v 1.62 mg/dL; P < .05). Two patients in the NANB groups and 3 in the control group required early retransplantation for graft primary nonfunction. One case of NANB FHF appeared to recur at 6 months but not after subsequent retransplantation. NANB FHF is not associated with hepatitis A, B, C, D, or E in plasma. It has a later age of onset but a similar clinical course to other forms of FHF and appears to preferentially affect women.

Adolescent↗
PubMed1996

[Intermittent prophylaxis in febrile seizures with oral diazepam: study of 82 cases].

We present our results of intermittent prophylaxis with oral diazepam in febrile seizures. We treated 82 patients aged between 3 months and 5 years. They have had simple or complex febrile seizures. Recurrence occurred in 22 patients (26%), none had a long-lasting febrile convulsion. Transient side effects occurred in 21.95% of the cases. We conclude that diazepam is a safe and effective drug for prophylaxis of febrile seizures when used as soon as any sign of illness appears. We suggest, however, that the administration of the drug should be indicated if the child presents at least one consistent predictor of risk of recurrent febrile seizures.

Child, Preschool↗
PubMed1996

Significance of the presence of antibodies against hepatitis C virus in asymptomatic blood donors.

In order to determine the significance of anti-hepatitis C virus (anti-HCV) antibodies in blood donors, 46 consecutive asymptomatic individuals were recruited at the blood bank of Hospital São Paulo, São Paulo, Brazil. They were submitted to an interview to collect epidemiological data and to clinical examination and blood samples were obtained for biochemical, serological and virological analysis. All patients were followed for a minimum period of six months and those with abnormal mean alanine aminotransferase (ALT) levels were submitted to a liver biopsy after giving informed consent. Hepatitis C virus RNA (HCVRNA) was detected by the polymerase chain reaction (PCR) in 22/47 (47.8%) patients and this finding was associated with parenteral risk factors (P = 0.03) and ethanol abuse (P = 0.03). HCVRNA positivity was also associated with abnormal levels of ALT (P < 0.001) and gamma-glutamyl transpeptidase (gamma-GT) (P = 0.01). Abnormal ALT levels were good marker of viremia, with 86.4% sensitivity and 79.2% specificity. Twenty-three patients with elevated mean ALT levels were submitted to a liver biopsy and histopathological changes were observed in 17 of them (73.9%). HCVRNA positivity was associated with severe forms of hepatic disease (chronic hepatitis and cirrhosis). These results indicate the need for a judicious evaluation of all anti-HCV-positive blood donors, including clinical examination, biochemical tests and liver histology when ALT is persistently elevated.

Adult↗
PubMed1995

Comparison of three different schedules of vaccination against hepatitis B in health care workers.

Health care workers (HCW) are a group at risk for hepatitis B virus (HBV) infection; as a result, vaccination is recommended. However, elevated cost of the vaccination schedule is one of the limiting factors to this approach. Our aim in this study was to evaluate alternative schedules for vaccination against hepatitis B, in order to obtain safe immunization with reduced costs. We studied 300 HCW, randomized to be submitted to one of three vaccination schedules against hepatitis B: Group A--three doses of 20 micrograms i.m. (n = 103); Group B--first dose i.d. (2 micrograms), second and third doses i.m. (20 micrograms) (n = 97); Group C--first and second doses i.d. (2 micrograms), third dose i.m. (20 micrograms) (n = 100). All individuals received recombinant vaccine at 0, 1 and 6 months. After the first dose, there was no difference among the three schedules, either in terms of anamnestic response or in seroconversion rate. After the second dose, there was statistical difference among the three schedules (A > B > C), in terms of seroconversion rates. After the third dose, seroconversion rates were 92.2% in Group A and 92.8% in group B; geometric mean titers (GMT) in Group B (789.6 UI l-1) were similar to group A (1248.0 UI l-1). Group C presented a seroconversion rate of 78% and a GMT of 323.0 UI l-1, both statistically inferior to other schedules. We concluded that the schedule applied in Group B had similar results when compared to schedule A, with estimated savings of 30% in vaccine costs.(ABSTRACT TRUNCATED AT 250 WORDS)

Adult↗
PubMed1995

Environmental transmission of hepatitis B and hepatitis C viruses within the hemodialysis unit.

The hepatitis B virus (HBV) can be transmitted in the dialysis setting through blood transfusions and environmental surfaces. Transfusion related hepatitis C virus (HCV) infection is very well known, but only recently the environmental transmission of this virus was postulated. In order to study the prevalence, mechanisms of transmission, and the ALT patterns of HBV and HCV infections in hemodialysis and CAPD patients before the implementation of HBV vaccination and HCV screening in the blood bank, we conducted a study from January 1987 to January 1990. Sera from 185 hemodialysis and 124 CAPD patients were stored in this period and later analyzed for HBsAg, anti-HBc, anti-HBs, and anti-HCV (second generation ELISA). The prevalence of any HBV marker was 55.7% (103/185) for hemodialysis patients and 31.5% (39/124) for CAPD patients (hemodialysis vs. CAPD, p < 0.001). The prevalence of positive anti-HCV was 35.1% (65/185) for hemodialysis and 33.9% (42/124) for CAPD patients (not significant). There was a significant association between HBV markers positivity and anti-HCV positivity. The multivariate analysis of risk factors revealed an association of the positivity of each virus with the duration of renal replacement therapy (RRT), number of previous blood transfusions, and past history of hemodialysis treatment. Thus, besides the transfusion-related transmission, hemodialysis environmental transmission may also occur for both viruses. The findings of a high prevalence of both viruses and evidence for environmental transmission in the dialysis setting are of major importance for the planning of future preventive measures.

Adolescent↗
PubMed1995

Incidence of and risk factors for hepatitis B virus and hepatitis C virus infection among haemodialysis and CAPD patients: evidence for environmental transmission.

Hepatitis B virus (HBV) serum markers (HBsAg, anti-HBs, anti-HBc) and antihepatitis C antibody (anti-HCV) were prospectively followed in haemodialysis and CAPD patients. From January 1987 to January 1990, 185 patients on haemodialysis and 124 on CAPD were analysed. Among patients susceptible to HBV (69 on haemodialysis and 70 on CAPD), there were 17 HBsAg seroconversions on haemodialysis (0.19/patient-year) and 1 on CAPD (0.01/patient-year). A Cox proportional hazards model showed that haemodialysis treatment was the only risk factor significantly associated with HBV infection, thus suggesting transmission through the environment. Regarding hepatitis C, 83 anti-HCV-negative patients on haemodialysis and 46 on CAPD were followed. There were 18 seroconversions on haemodialysis (0.15/patient-year) and two seroconversions on CAPD (0.03/patient-year). Haemodialysis treatment was also the only risk factor significantly associated with a higher risk of HCV infection. The hazard ratio for HCV infection in haemodialysis patients was 5.7 compared to CAPD patients. Nevertheless, for one patient on CAPD treatment transfusions were the only possible source of HCV infection. In conclusion, both viruses were transmitted mainly through the haemodialysis environment, but the role of transfusions could not be excluded.

Adolescent↗