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Biomedical subjects

S S Silva

Publications and source records attributed to S S Silva.

At least 37 records · Page 2Linked to original sources
PubMed1994

Babesia bovis: infectivity of an attenuated strain of Brazilian origin for the tick vector, Boophilus microplus.

In order to verify the infectivity and transovarian transmission of one strain of Babesia bovis of Brazilian origin, attenuated by repeated passages in splenectomized calves to the biological tick vector, Boophilus microplus, an inoculation of that strain was performed in hemoparasite-free calves infested with hemoparasite-free ticks. Subsequently, engorged female ticks were collected to examine hemolymph and progeny for presence of developing stages of Babesia bovis. Using an optical microscope, intrahemocytic merozoites were observed in female hemolymph on the second and fourth days, respectively, after ticks dropped from calves. By histological observation of F1 larvae, after more than 24 h of adherence on calves, sporokinetes and small merozoites were present in the samples of hemolymph. These results confirmed the maintenance of infectivity by the vaccine strain attenuated after 26 passages for tick Boophilus microplus.

Animals↗
PubMed1994

Mitral valvuloplasty with a new prosthetic ring. Analysis of the first 105 cases.

From October 1987 to March 1993, 105 patients were studied who have undergone valvuloplasty with an open ring. They ranged from 5 to 79 years (mean 30); 33 (31.4%) were under 16. All patients had mitral insufficiency, alone in 62 (59.0%) and associated with mitral stenosis (double mitral lesion) in 43 (41.0%). In the majority of the cases, the aetiology was rheumatic (78.1%); active in 10 (9.5%) patients. Three patients (2.9%) were in class II, 42 (40.0%) in class III, 57 (54.3%) in class IV and 3 (2.9%) in class V. Ten patients (9.5%) had isolated ring implantation while the remaining underwent associated procedures on the leaflets, chordae and papillary muscles. There were two (1.9%) hospital deaths, and six patients (5.7%) had to be reoperated. On the 30th (mean) postoperative day, 75 (71.4%) patients were reevaluated by catheterization, echo Doppler or both to confirm the effectiveness of the techniques employed. The mitral valve was functioning normally or with mitral regurgitation + in 63 (84.0%) patients, mitral regurgitation + + in 2 (2.7%), mitral regurgitation + + + in 5 (6.7%), mitral stenosis + in 4 (5.3%), and mitral stenosis + + in 1 (1.3%) patient. The results were therefore considered excellent in 63 (84.0%) patients with either normal mitral valve or mitral regurgitation +, good in 6 (8.0%) patients with mitral regurgitation + + and/or mitral stenosis +, and poor in 6 (8.0%) patients with mitral regurgitation + + + and/or mitral stenosis + +. Two deaths (1.9%) occurred within the first 7 months of follow-up. Patients were evaluated clinically 1-67 months postoperatively (mean 27):90 (85.7%) were in class I, 4 (3.8%) in class II, 4 (3.8%) in class III and 1 (1.0%) in class IV.(ABSTRACT TRUNCATED AT 250 WORDS)

Actuarial Analysis↗
PubMed1994

[Use of tranexamic acid for bleeding control in myocardial revascularization].

PURPOSE: To compare two groups of 80 patients undergoing to myocardial revascularization with the use of antifibrinolytic drug tranexamic acid and its efficacy in reduce bleeding and blood transfusion. METHODS: Prospective analysis of two groups of 80 patients. Group A-no antifibrinolytic therapy (dec 91-may 92) and group B-fibrinolytic therapy-tranexamic acid-10g EV (jun-dec/92). Quantification of mediastinal drainage over 12h as well as the blood or derivatives received at the same time. RESULTS: Hospital mortality: group A-3.8%, group B-2.5%. Drainage (12h): group A-602 +/- 547 ml and group B-260 +/- 260 ml (p < 0.001). Blood transfusion (12h): group A-1,782 +/- 1,163 ml and group B-1,105 +/- 839 ml (p < 0.001). COMPLICATIONS: group A-two cases of intraoperative myocardial infarction, one episode of jaundice; group B-one case of intraoperative MI, one reoperation for bleeding control, one episode of jaundice, one of renal insufficiency, two mediastinitis and one seizure. The mean hospitalization time was ten days in both groups. CONCLUSION: Tranexamic acid was an effective drug in bleeding control and in reducing blood transfusion in the postoperative of patients submitted to myocardial revascularization.

Adult↗
PubMed1994

[Surgical correction of anomalous venous connection of the left lung without extracorporeal circulation].

Surgical correction of anomalous pulmonary venous connection from the left lung to the innominate vein (through a vertical vein) without cardiopulmonary bypass, was performed in two patients, with excellent evolution. After median sternotomy, the ascending vertical vein was cut obliquely close to the vein, and connected to the left atrial appendage. In the postoperative period, the patients were in NYHA class I and the hemodynamic study showed normal venous drainage from the left lung to the left atrium.

Adolescent↗
PubMed1990

[A new reconstructive technique in cases of mitral insufficiency caused by the elongation of the chordae tendineae of the anterior cusp. A case report].

A new technique is proposed for mitral incompetence due to elongated chordae tendineae of the anterior leaflet. It consists in shortening the chordae tendineae of the leaflet level. First, we make a longitudinal orifice in the anterior leaflet just near its free edge and the elongated chordae tendineae. Through the orifice and with the help of a micro nerve hook we pull the elongated chordae the necessary to keep the anterior leaflet in the same level of the posterior leaflet. The orifice is then closed with a polipropilene 5-0 suture. The mitral annuloplasty was performed with a Gregori IMC prosthetic ring. The excellent clinical and laboratorial data suggest that mitral insufficiency due to elongated chordae tendineae can be corrected by this technique.

Adolescent↗
PubMedDate not supplied

Xylitol production from sugarcane bagasse hydrolyzate in fluidized bed reactor. Effect of air flowrate.

Cells of Candida guilliermondii immobilized onto porous glass spheres were cultured batchwise in a fluidized bed bioreactor for xylitol production from sugarcane bagasse hemicellulose hydrolyzate. An aeration rate of only 25 mL/min ensured minimum yields of xylose consumption (0.60) and biomass production (0.14 g(DM)/g(Xyl)), as well as maximum xylitol yield (0.54 g(Xyt)/g(Xyl)) and ratio of immobilized to total cells (0.83). These results suggest that cell metabolism, although slow because of oxygen limitation, was mainly addressed to xylitol production. A progressive increase in the aeration rate up to 140 mL/min accelerated both xylose consumption (from 0.36 to 0.78 g(Xyl)/L.h) and xylitol formation (from 0.19 to 0.28 g(Xyt)/L.h) but caused the fraction of immobilized to total cells and the xylitol yield to decrease up to 0.22 and 0.36 g(Xyt)/g(Xyl), respectively. The highest xylitol concentration (17.0 g(Xyt)/L) was obtained at 70 mL/min, but the specific xylitol productivity and the xylitol yield were 43% and 22% lower than the corresponding values obtained at the lowest air flowrate, respectively. The concentrations of consumed substrates and formed products were used in material balances to evaluate the xylose fractions consumed by C. guilliermondii for xylitol production, complete oxidation through the hexose monophosphate shunt, and cell growth. The experimental data collected at variable oxygen level allowed estimating a P/O ratio of 1.35 mol(ATP)/mol(O) and overall ATP requirements for biomass growth and maintenance of 3.4 mol(ATP)/C-mol(DM).

Bioreactors↗
PubMedDate not supplied

Aspects of the cell growth of Candida guilliermondii in sugar cane bagasse hydrolysate.

In this work the behavior of the growth of Candida guilliermondii FTI 20037 in sugar cane bagasse hemicellulosic hydrolysate on various oxygen transfer rates was investigated. The yeast was able to grow and produced xylitol at different performance levels. At 1.0 vvm (volume of air per volume of medium per minute) the highest growth with 24.4 g/l was observed, but no xylitol was produced. At aeration rate of 0.5 vvm the growth was lower, but therefore slight amounts of xylitol (xylitol yield factor-Yp/s = 0.15 g/g) were observed. The lowest cell concentration (10.7 g/l) and the highest xylitol yield (Yp/s = 0.46 g/g) was observed when aeration was changed from 0.5 vvm to 0.05 vvm after 14 h.

Aerobiosis↗
PubMedDate not supplied

Upstream parameters affecting the cell growth and xylitol production by Candida guilliermondii FTI 20037.

The effects of yeast extract (0-10 g/l), methanol (0-10% v/v), acetic acid (0-1.0 g/l), furfural (0-0.5 g/l), glucose (0-30 g/l), inoculum age (15-70 h) and product concentration (18-230 g/l) on the xylose-xylitol conversion by Candida guilliermondii FTI 20037 were studied. The xylitol specific productivity increased about 35% at a yeast extract concentration of 1.0 g/l, whereas glucose showed a strong inhibitory effect on the xylitol production and a stimulating effect on the growth of C. guilliermondii. Methanol, acetic acid and furfural under the employed concentrations did not show any positive effect neither on the growth or on the xylose-xylitol conversion by the yeast. The inoculum age showed a strong influence on xylitol formation and the best fermentative parameters were attained using a 40-h inoculum age. A xylitol concentration in the fermentation medium higher than 80 g/l inhibited markedly the xylitol productivity by the yeast C. guilliermondii.

Acetic Acid↗
PubMedDate not supplied

Downstream processing for xylitol recovery from fermented sugar cane bagasse hydrolysate using aluminium polychloride.

Xylitol, a sweetener comparable to sucrose, is anticariogenic and can be consumed by diabetics. This sugar has been employed successfully in many foods and pharmaceutical products. The discovery of microorganisms capable of converting xylose present in lignocellulosic biomass into xylitol offers the opportunity of producing this poliol in a simple way. Xylitol production by biotechnological means using sugar cane bagasse is under study in our laboratories, and fermentation parameters have already been established. However, the downstream processing for xylitol recovery is still a bottleneck on which there is only a few data available in the literature. The present study deals with xylitol recovery from fermented sugar cane bagasse hydrolysate using 5.2 g/l of aluminium polychloride associated with activated charcoal. The experiments were performed at pH 9, 50 degrees C for 50 min. The results showed that aluminium polychloride and activated charcoal promoted a 93.5% reduction in phenolic compounds and a 9.7% loss of xylitol from the fermented medium, which became more discoloured, facilitating the xylitol separation.

Alum Compounds↗