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Biomedical subjects

E Villegas

Publications and source records attributed to E Villegas.

12 recordsLinked to original sources
PubMed2006

Use of the pupal/demographic-survey technique to identify the epidemiologically important types of containers producing Aedes aegypti (L.) in a dengue-endemic area of Venezuela.

As dengue continues to emerge as a major public-health problem world-wide, efforts to control the dengue vector Aedes aegypti must become more effective and efficient. Results from larval and pupal surveys applied in Venezuela illustrate the uniqueness of the information gained from pupal surveys; information that is lost when traditional Stegomyia indices are calculated. As most Ae. aegypti pupae will emerge to become adults, controlling the containers that produce the most pupae could have the greatest impact on the adult population. Pupal-survey results in Venezuela showed that large (150- to 200-litre) water drums produce the greatest number of pupae throughout the year. In the rainy season, approximately 70% of all pupae are found in these drums or in tyres, buckets and tanks. Over 80% of pupae in the dry season are found in drums and tanks alone. By targeting only those domestic breeding containers that produce the greatest number of pupae, control efforts may be streamlined to have the greatest impact on reducing the local adult Ae. aegypti population.

Aedes↗
PubMed2004

Rapid and efficient identification of cysteine-rich peptides by random screening of a venom gland cDNA library from the hexathelid spider Macrothele gigas.

We identified novel 10 multi-cysteine peptides, namely Magi 7-16, from the spider Macrothele gigas by simple random cDNA screening of the venom gland. Mass analysis of the crude venom detected the mass numbers of the cross-linked forms of all peptides, confirming their presence in the venom. Magi 11, a C-terminus amidated peptide, was chemically synthesized and was indistinguishable from the native peptide proving the feasibility of the method for peptide identification. Moreover, toxicological assays showed diverse lethal or paralytic activities of these peptide toxins on mice and/or insects.

Amino Acid Sequence↗
PubMed2001

Characterization of unique amphipathic antimicrobial peptides from venom of the scorpion Pandinus imperator.

Two novel antimicrobial peptides have been identified and characterized from venom of the African scorpion Pandinus imperator. The peptides, designated pandinin 1 and 2, are alpha-helical polycationic peptides, with pandinin 1 belonging to the group of antibacterial peptides previously described from scorpions, frogs and insects, and pandinin 2 to the group of short magainin-type helical peptides from frogs. Both peptides demonstrated high antimicrobial activity against a range of Gram-positive bacteria (2.4-5.2 microM), but were less active against Gram-negative bacteria (2.4-38.2 microM), and only pandinin 2 affected the yeast Candida albicans. Pandinin 2 also demonstrated strong haemolytic activity (11.1-44.5 microM) against sheep erythrocytes, in contrast with pandinin 1, which was not haemolytic. CD studies and a high-resolution structure of pandinin 2 determined by NMR, showed that the two peptides are both essentially helical, but differ in their overall structure. Pandinin 2 is composed of a single alpha-helix with a predominantly hydrophobic N-terminal sequence, whereas pandinin 1 consists of two distinct alpha-helices separated by a coil region of higher flexibility. This is the first report of magainin-type polycationic antimicrobial peptides in scorpion venom. Their presence brings new insights into the mode of action of scorpion venom and also opens new avenues for the discovery of novel antibiotic molecules from arthropod venoms.

Amino Acid Sequence↗
PubMed1998

Serum and muscle levels of alpha-tocopherol, ascorbic acid, and retinol are normal in chronic alcoholic myopathy.

Some authors have suggested a possible loss of antioxidant factors in alcoholic skeletal myopathy. To assess the relationship between ethanol consumption and serum and muscle levels of alpha-tocopherol, ascorbic acid, and retinol in chronic alcoholics with and without skeletal myopathy, a prospective cross-sectional study was performed in the Alcohol Unit of a 1000-bed university hospital. Twenty-five chronic male alcoholic patients (10 with skeletal myopathy) and 15 male controls of similar age were included. Evaluation of daily and lifetime ethanol consumption, assessment of anthropometric and protein nutritional parameters, and open biopsy of the left deltoid muscle were performed, as well as determinations of serum and muscle levels of retinol, alpha-tocopherol, and ascorbic acid by HPLC analysis. Ten of the 25 chronic alcoholic patients presented histological criteria of skeletal myopathy. Four alcoholics presented caloric malnutrition and three protein malnutrition. All of the muscle biopsies of the control group were entirely normal, as were their nutritional studies. The serum and muscular levels of alpha-tocopherol, ascorbic acid, and retinol were normal and were similar in both alcoholics and controls. Except for serum retinol, these values were also similar in alcoholic patients with or without skeletal myopathy. In the univariate analysis, we identified the total lifetime dose of ethanol (p < 0.003), the muscle arm area (p < 0.05), and serum levels of prealbumin (p < 0.03) and retinol-binding protein (p < 0.05) as factors influencing the development of alcoholic myopathy. However, in multivariate analysis, the total lifetime dose of ethanol was the only independent factor in relation to alcoholic myopathy (p < 0.003). Serum and muscle levels of the antioxidants alpha-tocopherol, ascorbic acid, and retinol do not influence the presence of skeletal myopathy in chronic alcoholic patients.

Adult↗
PubMed1997

Primary central nervous system lymphoma of T-cell origin: description of two cases and review of the literature.

Primary lymphomas of the central nervous system (PLCNS) of T-cell lineage are unusual. It has been suggested that T-cell PLCNS, compared to those of B-cell origin, present some differences in relation to age of presentation, gender, location of the tumor and survival. We describe two cases with T-cell PLCNS and review 22 parenchymatous T-cell PLCNS reported in the English literature. Age, gender and survival of the whole series of 24 T-cell PLCNS did not differ from that reported in large series of PLCNS where the great majority were of B-cell origin. In contrast, a location in the posterior fossa was found in 54% of T-cell PLCNS, whereas this location ranged from 12 go 29% in series of, mostly B-cell, PLCNS. T-cell PLCNS had a higher frequency (33%) of the histologic low grade small lymphocytic lymphoma than B-cell PLCNS (5%). Analysis of six T-cell PLCNS long-term survivors showed that half of them had low grade lymphomas. We conclude that T-cell PLCNS do not differ from those of B-cell origin in age of presentation or gender, but they have a preference to develop in the posterior fossa and a higher frequency of low grade histology which would probably explain the longer survival in some patients.

Adult↗
PubMed1994

Human retina expresses both constitutive and inducible isoforms of nitric oxide synthase mRNA.

The present study provided evidence for the presence of two forms of nitric oxide synthase(NOS) gene in the human retina. Expression of retinal constitutive type(rbNOS) and inducible type(riNOS) of NOS was detected in human retinal poly A+RNA by reverse transcriptase polymerase chain reaction (RT-PCR) method. The deduced amino acid sequence of the human retinal rbNOS showed more than 99% homology with human brain bNOS and that of riNOS was identical to the chondrocytes inducible iNOS with the exception for one amino acid. These differences in amino acid sequences of rbNOS and riNOS, with their counterparts in human brain and human chondrocytes sequences, were only in the non-cofactor binding sites. Northern blot analysis of the human retinal poly A+RNA and total RNA, using the PCR-amplified riNOS probe revealed the existence of riNOS message with the appearance of the band with the expected size of 4.4kb, while the message for rbNOS was not detectable. This was the first report of the deduced nucleotide sequence identification of two NOS genes from a human tissue, while there had been earlier reports from culture cells.

Adolescent↗
PubMed1993

Solid state fermentation: acid protease production in controlled CO2 and O2 environments.

The effect of the partial pressure of O(2) and CO(2) on the acid protease production in solid state fermentation by Aspergillus niger on wheat bran was studied. A fermentation system was used, which allowed on-line reactor measurements and continuous data acquisition of pH, temperature, gas flow, pressure drop and CO(2) production. Six paired combinations of CO(2) and O(2) concentrations were studied. The results showed a direct relationship between pressure drop, production of CO(2) and temperature increase. The pH evolution patterns were similar in all cases but different if the measurements were made on-line or on a liquid homogenate of the fermented substrate. Acid protease production was increased when the gas had 4% CO(2), (vol/vol), and it reached its highest level, a 43% increase over air, with a mixture of 4% CO(2) and 21% O(2). The protease production was strongly related to the mold metabolic activity as represented by the total CO(2) evolved.

Journal Article↗
PubMed1993

Growth of Candida utilis in solid state fermentation.

In this work, the growth of the yeast Candida utilis on different solid substrate (wheat bran) and supports (sugarcane bagasse and Amberlite resin) imbibed with a liquid culture medium was studied. Growth was followed by sugars consumption, carbon dioxide production rate (CDPR) and cell count. The results showed the ability of the yeast to grow on the three solid media with fairly good viability and total dextrose consumption in the case of sugarcane bagasse and Amberlite, and partial consumption of wheat bran sugars. After two or three days of culture, a five hundred fold increase in cell population was observed.

Journal Article↗
PubMed1993

Relationship between ethanol-related diseases and nutritional status in chronically alcoholic men.

Two-hundred and fifty chronically alcoholic men (mean age, 41 +/- 11 years) entering an alcoholism treatment program were studied. Detailed clinical history, nutritional assessment and measurement of muscle strength by electronic myometer were performed in each case. In addition, hepatic ultrasonography and liver biopsy, echocardiography and radionuclide cardiac scanning, and electrophysiologica testing of peripheral nerves were performed when there was clinical evidence of liver disease, cardiomyopathy or neuropathy, respectively. Alcoholic cirrhosis was diagnosed in 20 cases, skeletal myopathy in 117, dilated cardiomyopathy in 20 and peripheral neuropathy in 41 cases. No patients with chronic myopathy or cardiomyopathy showed either clinical or laboratory evidence of malnutrition. Patients with cirrhosis showed a significantly lower lean body mass than controls (P = 0.03) and significantly lower nutritional protein levels than those alcoholics without cirrhosis. Alcoholics with peripheral neuropathy had significantly lower anthropometric parameters and nutrition protein levels than their counterparts (P < 0.001). However, in the multivariate analysis, the only independent factor for developing these complications of alcoholism was the total lifetime dose of ethanol (P < 0.001). We conclude that alcohol-related diseases are common in asymptomatic alcoholic men and these diseases appear to be due to an accumulative toxic effect of ethanol. Age and nutritional status do not seem to play a part in the development of such diseases.

Alcoholism↗