Biomedical subjects

R Oliveira

Publications and source records attributed to R Oliveira.

11 recordsLinked to original sources

PubMed2001

Hydraulic characteristics of an anoxic rotating biological contactor: influence of biofilm.

The hydraulic characteristics of an anoxic rotating biological contactor were studied under different flow rates. The experiments were carried out with the reactor clean (without biomass) and containing denitrifying biofilm (Alcaligenes denitrificans) covering the disks. Residence Time Distribution (RTD) experiments were performed by the stimulus-response technique using lithium chloride as tracer. Experiments without biomass revealed the existence of hydraulic dead volumes (around 40% for hydraulic residence time of 0.94 and 2 hours) that occur in corners, where stagnant eddies form. When in normal operation, with the disks covered by biofilm and with biogas production, these values decreased significantly. For hydraulic residence time (HRT) of 2 hours a minimum dead volume was observed, being appropriate to run the reactor under this condition, from the hydraulic viewpoint. The Dispersion number decreased with increasing HRT from 0.94 h on, for both types of experiment, without, and in the presence of biomass. For this HRT the dispersion number was maximal in both situations. A considerable diffusion of tracer into the biofilm was detected, being faster in the more hydrated biofilm, and Justifying the long tails observed in the RTD experimental curves.

Biofilms↗

PubMed2001

[Smoking time evolution among medical students, 1986, 1991, 1996].

OBJECTIVE: To evaluate trends in smoking habits among medical students in the last ten years. METHODS: In 1996, a cross-sectional survey of smoking habits was carried out among students in the first to the fifth year of medical school. Four hundred and nine students answered the questionnaire. A regular smoker was defined as someone who smokes one or more cigarettes a day at least for one month; former smokers were the ones who used to smoke in the past but not at the moment. Similar research was conducted in 1986 and 1991. RESULTS/CONCLUSIONS: Smoking prevalence was 11% compared with 14% in 1991 and 21% in 1986. Although there was a significant reduction of smoking in the last three years, the actual decrease from 1991 to 1996 was less than that observed from 1986 to 1991. In 1961, the prevalence of smoking increased in the last years of medical school. There were no significant differences regarding gender. Most of the students were in favor of not allowing smoking in both the school areas and hospital wards. They also mentioned in their questionnaire that smoking was poorly approached during medical school.

Adult↗

PubMed2001

Successful prevention of hiv transmission from mother to infant in Brazil using a multidisciplinary team approach.

OBJECTIVES: To determine the HIV vertical transmission rate (VTR) and associated risk factors by use of zidovudine and infant care education in Brazil. METHODS: Since 1995, a prospective cohort of HIV infected pregnant women has been followed at the Federal University of Rio de Janeiro. A multidisciplinary team was established to implement the best available strategy to prevent maternal-infant HIV transmission. Patients with AIDS or low CD(4) and high viral load received anti-retroviral drugs in addition to zidovudine. Children were considered infected if they had 2 positive PCR-RNA tests between 1 and 4 months of age, or were HIV antibody positive after 18 months. Education regarding infant treatment and use of formula instead of breast feeding was provided. RESULTS: Between 1995 and August, 2000, HIV status was determined for 145 infants. Compliance with intra-partum treatment, infant treatment and use of formula was 88.2%. Intra-partum zidovudine treatment was completed in 134/145 (92.6%) of patients; 88.1% had rupture of membranes < 4 hours; 85.4% of mothers were asymptomatic. The mean CD(4) count was 428.4 cells and mean viral load 39,050 copies. HIV vertical transmission rate was 4/145 (2.75%; CI: 0.1%-5.4%). The only risk factor significantly associated with transmission was a failure to use zidovudine intra-partum in 2 of the 4 mothers (50% versus 6.4% in non-transmitting mothers). A trend toward low CD(4) and high viral load at entry, and rupture of membranes > 4 hours were associated with increased HIV transmission. CONCLUSION: HIV vertical transmission in Brazil was reduced to a level similar to other countries with the most effective prevention programs using a multidisciplinary team approach. A high level of compliance for use of anti-retroviral drugs, the provision of health education to mothers, and use of formula for all exposed infants.

Adolescent↗

PubMed2000

GUP1 and its close homologue GUP2, encoding multimembrane-spanning proteins involved in active glycerol uptake in Saccharomyces cerevisiae.

Many yeast species can utilize glycerol, both as a sole carbon source and as an osmolyte. In Saccharomyces cerevisiae, physiological studies have previously shown the presence of an active uptake system driven by electrogenic proton symport. We have used transposon mutagenesis to isolate mutants affected in the transport of glycerol into the cell. Here we present the identification of YGL084c, encoding a multimembrane-spanning protein, as being essential for proton symport of glycerol into S. cerevisiae. The gene is named GUP1 (glycerol uptake) and, for growth on glycerol, is important as a carbon and energy source. In addition, in strains deficient in glycerol production it also provides osmotic protection by the addition of glycerol. Another open reading frame (ORF), YPL189w, presenting a high degree of homology to YGL084c, similarly appears to be involved in active glycerol uptake in salt-containing glucose-based media in strains deficient in glycerol production. Analogously, this gene is named GUP2. To our knowledge, this is the first report on a gene product involved in active transport of glycerol in yeasts. Mutations with the same phenotypes occurred in two other ORFs of previously unknown function, YDL074c and YPL180w.

Amino Acid Sequence↗

PubMed2000

Anti-hyperalgesic effect of electroacupuncture in a model of post-incisional pain in rats.

Electroacupuncture has been proposed to be a low cost and practical method that allows effective pain management with minimal collateral effects. In this study we have examined the effect of electroacupuncture against the hyperalgesia developed in a model of post-incisional pain in rats. A 1-cm longitudinal incision was made through the skin and fascia of the plantar region of the animal hind paw. Mechanical hyperalgesia in the incision was evaluated 135 min after the surgery with von Frey filaments. The tension threshold was reduced from 75 g (upper limit of the test) to 1.36 +/- 0.36 g (mean +/- SEM) in control rats. It is shown that a 15-min period of electroacupuncture applied 120 min after surgery to the Zusanli (ST36) and Sanyinjiao (SP6) points, but not to non-acupoints, produces a significant and long-lasting reduction of the mechanical hyperalgesia induced by the surgical incision of the plantar surface of the ipsilateral hind paw. The tension threshold was reduced from 75 to 27.6 +/- 4.2 g in animals soon after the end of electroacupuncture. The mechanical threshold in this group was about 64% less than in control. Electroacupuncture was ineffective in rats treated 10 min earlier with naloxone (1 mg/kg, ip), thus confirming the involvement of opioid mechanisms in the antinociceptive effects of such procedure. The results indicate that post-incisional pain is a useful model for studying the anti-hyperalgesic properties of electroacupuncture in laboratory animals.

Animals↗

PubMed1999

Mitochondrial function is differentially affected upon oxidative stress.

The mechanisms that lead to mitochondrial damage under oxidative stress conditions were examined in synaptosomes treated with ascorbate/iron. A loss of membrane integrity, evaluated by electron microscopy and by LDH leakage, was observed in peroxidized synaptosomes and it was prevented by pre-incubation with vitamin E (150 microM) and idebenone (50 microM). ATP levels decreased, in synaptosomes exposed to ascorbate/iron, as compared to controls. NADH-ubiquinone oxidoreductase (Cx I) and cytochrome c oxidase (Cx IV) activities were unchanged after ascorbate/iron treatment, whereas succinate-ubiquinone oxidoreductase (Cx II), ubiquinol cytochrome c reductase (Cx III) and ATP-synthase (Cx V) activities were reduced by 55%, 40%, and 55%, respectively. The decrease of complex II and ATP-synthase activities was prevented by reduced glutathione (GSH), whereas the other antioxidants tested (vitamin E and idebenone) were ineffective. However, vitamin E, idebenone and GSH prevented the reduction of complex III activity observed in synaptosomes treated with ascorbate/iron. GSH protective effect suggests that the oxidation of protein SH-groups is involved in the inhibition of complexes II, III and V activity, whereas vitamin E and idebenone protection suggests that membrane lipid peroxidation is also involved in the reduction of complex III activity. These results may indicate that the inhibition of the mitochondrial respiratory chain enzymatic complexes, that are differentially affected by oxidative stress, can be recovered by specific antioxidants.

Adenine Nucleotides↗

PubMed1998

Effect of a protective-ventilation strategy on mortality in the acute respiratory distress syndrome.

BACKGROUND: In patients with the acute respiratory distress syndrome, massive alveolar collapse and cyclic lung reopening and overdistention during mechanical ventilation may perpetuate alveolar injury. We determined whether a ventilatory strategy designed to minimize such lung injuries could reduce not only pulmonary complications but also mortality at 28 days in patients with the acute respiratory distress syndrome. METHODS: We randomly assigned 53 patients with early acute respiratory distress syndrome (including 28 described previously), all of whom were receiving identical hemodynamic and general support, to conventional or protective mechanical ventilation. Conventional ventilation was based on the strategy of maintaining the lowest positive end-expiratory pressure (PEEP) for acceptable oxygenation, with a tidal volume of 12 ml per kilogram of body weight and normal arterial carbon dioxide levels (35 to 38 mm Hg). Protective ventilation involved end-expiratory pressures above the lower inflection point on the static pressure-volume curve, a tidal volume of less than 6 ml per kilogram, driving pressures of less than 20 cm of water above the PEEP value, permissive hypercapnia, and preferential use of pressure-limited ventilatory modes. RESULTS: After 28 days, 11 of 29 patients (38 percent) in the protective-ventilation group had died, as compared with 17 of 24 (71 percent) in the conventional-ventilation group (P<0.001). The rates of weaning from mechanical ventilation were 66 percent in the protective-ventilation group and 29 percent in the conventional-ventilation group (P=0.005): the rates of clinical barotrauma were 7 percent and 42 percent, respectively (P=0.02), despite the use of higher PEEP and mean airway pressures in the protective-ventilation group. The difference in survival to hospital discharge was not significant; 13 of 29 patients (45 percent) in the protective-ventilation group died in the hospital, as compared with 17 of 24 in the conventional-ventilation group (71 percent, P=0.37). CONCLUSIONS: As compared with conventional ventilation, the protective strategy was associated with improved survival at 28 days, a higher rate of weaning from mechanical ventilation, and a lower rate of barotrauma in patients with the acute respiratory distress syndrome. Protective ventilation was not associated with a higher rate of survival to hospital discharge.

Adult↗

PubMed1997

Identification and epidemiological relationship of Rhodococcus equi isolated from cases of lymphadenitis in cattle.

The present study was designed to comparatively investigate 10 Rhodococcus equi isolates from cases of lymphadenitis in cattle. The isolates could be identified by cultural and biochemical properties. By serotyping the R. equi isolates 9 and 1, cultures could be classified as Nakazawa's serotypes 15 and 8, respectively. The isolates did not agglutinate rabbit erythrocytes, were uniformly susceptible to most of the antibiotics tested, did not contain plasmids nor expressed virulence-associated proteins and yielded identical patterns in protein fingerprinting. To further analyze the epidemiological relationships, the isolates were additionally subjected to DNA fingerprinting. This was performed by pulsed-field gel electrophoresis (PFGE) after digestion of the chromosomal DNA with the endonuclease AsnI. PFGE analysis of the chromosomal DNA revealed 4 DNA restriction groups with DNA pattern I with 7 isolates as predominant group and DNA pattern II to IV with one isolate, respectively. The present results indicate that a single R. equi clone belonging to Nakazawa's serotype 15 and according to PFGE to DNA restriction pattern I of the present investigation seems to be responsible for most of the cases of lymphadenitis of cattle described in this study.

Actinomycetales Infections↗

PubMed1995

Short report: hepatitis E infection in the Brazilian Amazon.

This is the first report of serologic evidence of hepatitis E infection in Brazil. During a community-based survey of healthy individuals, six of 97 gold miners in the Amazon region of Mato Grosso had antibody to the virus. The mining camps have poor sanitation with a great potential for fecal-oral transmission of disease. Since levels of hepatitis E antibodies may quickly wane, studies to directly measure the incidence of seroconversion are planned to determine the intensity of transmission in this area.

Adult↗

PubMed1991

[Coronary angioplasty using last generation materials. Immediate results].

PURPOSE: To present immediate results of percutaneous transluminal coronary angioplasty (PTCA) with the use of last generation catheter devices. METHODS: 74 patients underwent PTCA mean age 55 years the majority of them with disease of one vessel (92%) and good left ventricular function (88%). There was a total of 80 lesions treated, 26 type A and 54 type B according to the Task Force for Coronary Angioplasty of the American College of Cardiology--American Heart Association Classification. Results were analysed by separate observers: one clinical cardiologist (C), one cardiovascular surgeon (S) and two hemodynamicists (H1, H2). RESULTS: A significant fail in the degree of coronary obstruction was demonstrated post PTCA in the opinion of the observers: C = 83 +/- 10.7/9.0 +/- 14; S = 86 +/- 13.0/9.3 +/- 11; H1 = 88.6 +/- 7.0/8.5 +/- 12; H2 = 88.5 +/- 8.0/8.3 +/- 12 (P less than 0.001). Angiographic success was attained in 94.6% of the cases and the complication rate was low 2.7%. CONCLUSION: The high primary success and the low complication rates seen in this series can be attributed to the careful selection of cases and advanced performance of the catheterization devices that were used.

Adult↗

PubMedDate not supplied

Effect of daily saline, drug or blank injections on the susceptibility to the convulsant effect of drugs.

The daily intraperitoneal injection to rats of doses of metrazol (30 mg/Kg), strychnin sulfate (1 mg/Kg) or picrotoxin (1.2 mg/Kg) that were initially subconvulsant, caused after a number of days which varied with the drug, clonic convulsions in a high percentage of the animals. However, after 18 daily injections of saline there was a similar increase of seizure susceptibility to the 3 drugs. The daily handling of rats as for injection, either followed or not by actual abdominal pricking (blank injection), had a similar though less pronounced effect. In animals that were housed in the same room where the others were tested, but which were not handled, the above mentioned doses of metrazol, strychnine and picrotoxin had no convulsant effect. These results indicate that the procedure of submitting rats to daily intraperitoneal injections is not as unconsequential as is usually thought to be, and that it may induce neurological changes.

Animals↗