Biomedical subjects

A F Furtado

Publications and source records attributed to A F Furtado.

At least 19 recordsLinked to original sources

PubMed2004

[Comparative studies on endemic areas of bancroftian filariasis in Greater Recife, Brazil].

Two districts in Recife (Santo Amaro and Campo Grande) and two districts in Olinda (Sapucaia and Salgadinho), were selected for a comparative study of bancroftian filariasis in Greater Recife. Selection parameters included similar socio-economic, demographic, and endemic levels of lymphatic filariasis. In the districts studied, streets were chosen randomly. These clusters consisted of 110 people each. A population sample was stratified by sex and age: 0-4, 5-9, 10-14, 15-19, 20-29, 30-39, 40-49, 50-59 and 60 years old and over. The parasitological data were obtained by measuring thick blood smears (60 micro l), collected from 8:00 to 12:00 PM and processed and stained with hematoxylin. The data were described in tables, and logarithimic expression graphics were used to analyze parasitic densities. In general, Recife showed a prevalence of 13.5%, and Olinda 12.3%. Mean parasitic densities were 41 and 70 microfilariae/60 micro l (mf/60 micro l), respectively. Higher microfilaremic rates were observed in Recife for the 20-29-year age bracket and in Olinda in the 30-39-year bracket. The authors concluded that the disease has returned to former endemic levels, and the data described call for a reevaluation of control campaigns carried out by the Brazilian National Health Foundation, since the endemic has already reached serious proportions.

English Abstract↗

PubMed2003

Genetic differentiation of Aedes aegypti (Diptera: Culicidae), the major dengue vector in Brazil.

In 2000, Brazil reported 180,137 cases of dengue, approximately 80% of the total in the Americas. However, little is known about gene flow among the vector populations in Brazil. Random amplified polymorphic DNA (RAPD) was used to study the genetic structure of Aedes aegypti in 15 populations from five states, with a range extending 2,800 km. An analysis of 47 polymorphic RAPD loci estimated gene flow at the macro- (different states) and micro- (different cities) geographical levels. Genetic polymorphism was high (H(S) = 0.274), and high levels of genetic differentiation existed both between different states (G(ST) = 0.317) and between cities or neighborhoods in each state (G(ST) = 0.085-0.265). These values are higher than those described for any other populations of A. aegypti.

Aedes↗

PubMed2003

Screening of exogenous enzymes for ruminant diets: relationship between biochemical characteristics and in vitro ruminal degradation.

With the objective of developing a rational approach for the selection of feed enzymes for ruminants, 22 commercial enzyme products were examined in terms of protein concentration, enzymic activities on model substrates, and hydrolytic capacity, the latter determined from the release of reducing sugars from alfalfa hay and corn silage. An in vitro ruminal degradation assessment was carried out using the same substrates, untreated or treated with the 22 enzyme products at 1.5 microL/g forage DM. Stepwise regressions were then performed to establish relationships between these factors. Protein concentration and enzymic activities explained at least 84% (P < 0.01) of the variation in the release of reducing sugars from alfalfa and corn silage. Alfalfa DM degradation after incubation with ruminal fluid for 18 h was positively related to xylanase activity (R2 = 0.29, P < 0.01), but the same activity was negatively related to DM degradation of corn silage (R2 = 0.19, P < 0.05). Protease activity explained a further 10% of the alfalfa DM degradation (P < 0.10). Following sequential steps involving the determination of rate and extent of DM and fiber degradation, the best candidates for alfalfa and corn silage were selected. Enzyme products effective with alfalfa hay seemed to exert part of their effect during the pretreatment period, whereas enzymes effective with corn silage worked exclusively after ruminal fluid was added. This finding suggests that different modes of action of exogenous enzymes are attacking different substrates and may partly explain enzyme-feed specificity. In alfalfa, it seems that effective enzymes work by removing structural barriers that retard the microbial colonization of digestible fractions, increasing the rate of degradation. In corn silage, effective enzymes seem to interact with ruminal enzymes to degrade the forage more rapidly, which is consistent with previous findings of synergism between exogenous and ruminal enzymes.

Animal Feed↗

PubMed2002

Effect of a fibrolytic enzyme preparation from Trichoderma longibrachiatum on the rumen microbial population of dairy cows.

The effects of supplementing a dairy cow diet with incremental levels of a fibrolytic enzyme preparation (preparation B) from Trichoderma longibrachiatum on the rumen microbial population were investigated. Two cows fitted with rumen cannulae were each fed a diet containing barley-based concentrate (52%), maize silage (29%), and chopped alfalfa hay (19%), supplemented with 0, 1, 2, 5, or 10 L of preparation B per tonne of dry matter (DM). Preparation B stimulated numbers of total viable bacteria in a quadratic manner (P < 0.05), to approximately 230, 330, 390, and 250% at 1, 2, 5, and 10 L x t(-1) DM, respectively. Preparation B increased the numbers of cellobiose-utilizing (P < 0.01), xylanolytic (P < 0.05), and amylolytic bacteria (P < 0.05), but had no effect (P > 0.05) on numbers of cellulolytic bacteria. However, when bacterial numbers enumerated on each substrate were expressed as a proportion of total viable bacterial numbers, only cellobiose utilizers were stimulated, and this stimulation was limited to the 1 L x t(-1) DM level of preparation B (P < 0.05). The results of this study demonstrate that the inclusion of an exogenous fibrolytic enzyme preparation in dairy cow diets increased the numbers of rumen bacteria that utilize hemicelluloses and secondary products of cellulose digestion.

Animal Feed↗

PubMed2002

Genetic diversity in Brazilian populations of Aedes albopictus.

Random amplified polymorphic DNA (RAPD) analysis technique was undertaken in Aedes albopictus populations from three states in Brazil, Rio de Janeiro (RJ), Minas Gerais (MG) and Pernambuco (PE), to estimate the level of genetic variability and levels of genetic exchange between populations. Allele and genotype frequencies were measured on 47 RAPD loci. Average observed heterozigosity (Ho) ranged from 0.282 in MG to 0.355 in Casa Forte (PE) population. Genetic distances estimates indicated that RJ and MG were more genetically similar than populations from PE. Genetic variation observed in local Brazilian populations was attributed to genetic drift associated with restricted gene flow in recently established populations.

Aedes↗

PubMed1998

Absence of lysozyme (muramidase) in the intestinal Paneth cells of newborn infants with necrotising enterocolitis.

AIM: To determine immunocytochemically whether preterm and newborn infants with necrotising enterocolitis (NEC) show differences in numbers of lysozyme positive Paneth cells compared with normal controls, and to relate the findings to the possibility that lysozyme deficiency may facilitate the bacterial infections thought to be associated with this condition. METHODS: Tissues from 10 infants with NEC and from 11 matched controls were sectioned and stained immunocytochemically for lysozyme. Differences in the numbers of Paneth cells and degree of lysozyme positivity in the tissues were assessed. RESULTS: Tissues from NEC patients showed no, or very few, lysozyme positive Paneth cells, whereas controls showed strong positive staining. CONCLUSIONS: A deficiency or developmental defect in Paneth cells, resulting in an absence of lysozyme, may render the intestine more susceptible to bacterial infection, allowing organisms to adhere and translocate across the mucosa. Such enhancement of infection may contribute to the pathogenesis of NEC.

Bacterial Infections↗

PubMed1998

The LYMFASIM simulation program for modeling lymphatic filariasis and its control.

The LYMFASIM modeling framework for the transmission and control of the tropical parasitic disease lymphatic filariasis is described and its use in the context of an endemic community in north-eastern Brazil is illustrated. Lymphatic filariasis is a disease with a complex natural history with many unknowns. This complicates decision making with respect to control strategies. With LYMFASIM, a variety of hypotheses can be tested about the life history of the parasite Wuchereria bancrofti, its transmission from man to man through mosquitoes, the role of the immune system in regulating parasite numbers, the development of disease symptoms, and the effects of control measures (drug treatment or mosquito control). The implications of alternative assumptions and uncertainty about the quantification of parameters for the effectiveness of control strategies can be investigated. Thanks to the use of stochastic microsimulation, LYMFASIM is highly flexible and can be adapted and extended as new knowledge emerges.

Adolescent↗

PubMed1997

Intra-abdominal sepsis: an immunocytochemical study of the small intestine mucosa.

AIM: To investigate immunocytochemical changes in intestinal tissues from patients with intra-abdominal sepsis, and to relate the changes to the possibility of enhanced bacterial adhesion and translocation. METHODS: Tissues from 17 patients suffering from intra-abdominal sepsis and from controls were sectioned and stained immunocytochemically for IgA, IgM, secretory component, J chain, and HLA-DR. Differences in the distribution and characteristics of positively staining cells between the patient groups were assessed. RESULTS: Patients with intra-abdominal sepsis had noticeable reductions in numbers of IgA and IgM plasma cells, reduced J chain staining, and had little immunoglobulin on the surfaces of enterocytes. In contrast, HLA-DR positive cells were increased in the sepsis compared with the control group. The plasma cells present showed cytological changes suggestive of apoptosis. CONCLUSIONS: Stress associated with sepsis and its immediate causes might result in increased plasma glucocorticoid levels that bring about apoptosis of mucosal plasma cells (or their precursors). The consequent reduction in expression of IgA and IgM may favour bacterial adhesion to the enterocytes and facilitate bacterial translocation into the tissues.

Adult↗

PubMed1995

A monoclonal antibody against blood forms of Trypanosoma cruzi lyses the parasite in vitro and inhibits host cell invasion.

Monoclonal antibodies (mAbs) of the IgM isotypes were produced from mice immunized with blood forms of Trypansoma cruzi Y strain. Characterization of the epitope recognized by one of the mAbs, 164C11, as well as the effects of this mAb on complement-mediated lysis and host cell invasion are reported. Immunocytochemical analysis showed that the mAb was reactive with various strains of T. cruzi (Y, WSL, and Colombiana) as well as other trypanosomatids. The mAb 164C11 demonstrated a high complement-mediated lytic activity against bloodstream trypomastigotes, being more effective than chronic mouse serum. A protein with an apparent molecular weight of 72 kDa was detected by this mAb on all developmental stages of T. cruzi. Studies using periodate and endoglycosidase treatments suggested that the epitope is not a carbohydrate and seems to be located on the parasite membrane. In addition, preliminary results are presented, suggesting that the 72-kDa protein is involved in adhesion/or internalization of bloodstream trypomastigotes.

Animals↗

PubMed1995

Abnormal lymphatic function in presymptomatic bancroftian filariasis.

Despite the common association of filarial infection with elephantiasis, the great majority of those infected are in fact clinically asymptomatic microfilariae carriers. The assumption has been that infection but not disease exists in these presymptomatic persons. In an area Brazil where Wuchereria bancrofti is endemic, flow studies done with dynamic radionuclide lymphoscintigraphy were used to compare 30 limbs from asymptomatic microfilaremic subjects with 16 control limbs. Geometric mean values for T1/2 (19.8 vs. 37.7 min; P < .001), appearance time (7.9 vs. 27.9 min; P < .001), percent uptake at the region of interest (0.67% vs. 0.14%; P < .001), and peak activity (62.6 vs. 2.6 cps; P < .001) each indicated an enhanced pattern of rapid, increased lymph flow in asymptomatic microfilaremic subjects. The abnormal lymphatic function in these subjects indicates that current passive intervention strategies may need to change if the debilitating sequelae of this parasitic infection are to be avoided.

Adolescent↗

PubMed1995

Lymphoscintigraphic assessment of the effect of diethylcarbamazine treatment on lymphatic damage in human bancroftian filariasis.

Despite many millions of doses administered over the past 40 years, basic and crucial issues regarding the use, mode of action, and effectiveness of diethylcarbamazine (DEC) in many clinical situations remain unresolved. To directly investigate whether the well-known microfilaricidal and macrofilaricidal actions of DEC actually result in subsequent improvement in existing damage to lymphatic vessels or lymph nodes, 29 study subjects in Recife, Brazil were stratified into three groups according to the severity of clinical manifestations of lymphatic insufficiency. After baseline radionuclide lymphoscintigraphy was performed, subjects were treated with two courses of DEC separated by at least a six-month interval and then rescanned one year after the baseline scan. A side-by-side comparison of images obtained at baseline with those obtained at follow-up in 13 asymptomatic microfilaremic individuals, six individuals with filarial fever, and in 10 individuals with chronic pathology demonstrated essentially unchanged lymphatic morphology in all but one individual whose disease actually progressed in the face of therapy. We conclude that two 12-day treatment courses of DEC did not have a demonstrable direct or indirect effect on existing structural damage to the lymphatic system even in those individuals with preclinical disease.

Acute Disease↗

PubMed1994

Production of 2-aminobutyrate by Megasphaera elsdenii.

Production of the amino acid 2-aminobutyrate was studied in four strains of Megasphaera elsdenii grown on a lactate-based growth medium containing Bacto-casamino acids and yeast extract. Supplementation with threonine increased the production of 2-aminobutyrate in three of the four strains, but no substantial increase in production was noted with serine, methionine, or aspartate, all of which are potential sources for the precursor of 2-aminobutyrate, 2-oxobutyrate. L-Cycloserine, an inhibitor of alanine transaminases, decreased both alanine and 2-aminobutyrate production, suggesting that 2-aminobutyrate synthesis may share the same metabolic pathway as alanine synthesis or that 2-oxobutyrate can act as a substrate for alanine transaminases. Decreases in the production of 2-aminobutyrate were associated with a reduction in the catabolism of branched-chain amino acids in two of the four strains.

Amino Acids↗

PubMed1992

A simple method for detection of monoclonal isotypes.

A simple rapid method of enzyme labeled anti-isotype assay (ELIA) for detection of monoclonal isotype on hybridoma cells is proposed. This alternative method was first carried out on hybridoma cell lines 147C11 and 257C11 produced against Trypanosoma cruzi and male accessory secretion of Panstrongylus megistus, respectively. The monoclonal antibodies produced by these hybridoma were characterized by this method as IgM (147C11) and IgG1 (257C23) isotypes, allowing evaluation of isotype without having to wait until the concentration of antibody present in the supernatant itself rises. Results were confirmed by Ouchterlony immunodiffusion. The proposed method offers the advantages of a permanent rapid procedure for light microscopy.

Animals↗

PubMed1992

Study of humoral immune response in mammals immunized with Plasmodium falciparum antigenic preparations.

Six Plasmodium falciparum protein fractions, isolated under reducing conditions, were used to immunize mice, rabbits and the squirrel monkey Saimiri sciureus. Five or seven subcutaneous injections of each antigenic preparation, in conjunction with Freund's complete or incomplete adjuvants, were administered. This led to the development of specific antibodies detected by IFAT, ELISA or immunoblotting which inhibited merozoite reinvasion in in vitro P. falciparum cultures. This activity seems to be associated with rhoptry proteins contained in fractions Pf F2 and Pf F4.

Animals↗

PubMed1991

Partial purification and some properties of a hemolymph lectin from Panstrongylus megistus (Hemiptera, Reduviidae).

Hemagglutinating activity was studied in homogenates of three embryonic stages, and in the hemolymph of most instar larvae and in adult insects of Panstrongylus megistus, an important Chagas' disease vector in Brazil. A hemolymph lectin from the 5th instar larvae of P. megistus was purified through a biospecific adsorption by using formaldehyde-treated erythrocytes. The lectin fraction was desorbed with 0.2M D-galactose in 0.15M NaCl. The lectin fraction activity was inhibited by L-rhamnose, D-lactose, raffinose, D-galactose, and D-fucose. The electrophoretic pattern to native and acidic proteins resolved lectin fraction in two main bands with lectin activity. These bands were considered as multiple molecular forms or isoforms of P. megistus lectin. Under denaturating conditions, isoform 1 showed one band with apparent mol wt (MW) of 64 kDa while isoform 2 was resolved in two bands with MW of 64 and 33 kDa.

Adsorption↗

PubMed1987

Secretory activity and endocrine regulation of male accessory glands in the blood-sucking bug Panstrongylus megistus (Hemiptera: Reduviidae).

The epithelial cells of Panstrongylus megistus male accessory glands (MAG) present ultrastructural characteristics of a secretory cell. Their secretory products are accumulated in the lumen of the four MAG lobes. During the first 8 days of adult life a strong secretion activity occurs, accumulating enough material to produce the first spermatophore. Cerebral neurosecretions as well as juvenile hormone are both involved in MAG secretory activity regulation. Juvenile hormone seems to be the responsible for the stimulation of most protein synthesis in male accessory glands. Cerebral neurosecretion seems to be necessary to stimulate juvenile hormone production and release by the corpus allatum. Furthermore, neurosecretion is required for some polypeptides synthesis by MAG. Although topic application of precocene II to adult males does not reproduce the same effects on MAG as does allatectomy, this compound causes strong reduction on male reproductive capacity.

Animals↗

PubMedDate not supplied

Efficacy of Bacillus sphaericus in control of the filariasis vector Culex quinquefasciatus in an urban area of Olinda, Brazil.

The efficacy of Bacillus sphaericus 2362 against Culex quinquefasciatus was tested in 1991-94 in a major Brazilian endemic zone for bancroftian filariasis. Continuous selection pressure against the mosquito population was sustained for 18 months through treatment of 2500 potential breeding sites occurring within a 5.7-km2 urban area in the Metropolitan Region of Recife. The impact of this control intervention was evaluated by comparing entomological indices with those from an untreated area. Application of the larvicide kept the Cx. quinquefasciatus population density significantly lower when compared to the untreated area, despite some operational difficulties. Adult densities remained lower for at least 5 months after spraying ceased. Pre-trial microfilaria rates from the untreated and operational area were 13.1% and 7.2%, respectively. A 60% reduction in human exposure to infective bites was recorded as a consequence of this vector population control.

Animals↗

PubMedDate not supplied

Diagnosis of Wuchereria bancrofti infection by the polymerase chain reaction using urine and day blood samples from amicrofilaraemic patients.

A sensitive and specific polymerase chain reaction (PCR) based on a highly repeated deoxyribonucleic acid (DNA) sequence (188 bp; SspI repeat) was tested for the detection of Wuchereria bancrofti DNA in blood and urine samples collected during the day from individuals in Coque, Recife, Brazil, an endemic area for W. bancrofti. All microfilaraemic individuals were also positive by PCR, irrespective of the samples used. The PCR system was capable of detecting W. bancrofti DNA in amicrofilaraemic individuals: c. 93% were positive by PCR when day blood samples were used and 59.7% when urine samples collected at 07:00 were used. Thus, nocturnally periodic W. bancrofti infection can be detected in blood samples collected during the day, which is convenient for large-scale screening. In addition, non-invasive urine collection provided suitable samples for PCR, which is clearly advantageous for preliminary mass diagnosis.

Animals↗