Showing papers by "University of Costa Rica published in 1992"

The gene for an inherited form of deafness maps to chromosome 5q31

Abstract: Primary--i.e., nonsyndromal-postlingual deafness is inherited as an autosomal dominant phenotype in a large kindred in Costa Rica. Genetically susceptible individuals begin to lose hearing at low frequencies at about age 10 years, after language and speaking are learned. Deafness inevitably progresses by age 30 years to bilateral hearing loss of all frequencies. Intelligence, fertility, and life expectancy are normal. The family traces its ancestry to an affected founder born in Costa Rica in 1754. We have mapped the gene for deafness in this kindred to chromosome 5q31, between the markers IL9 and GRL, by linkage analysis involving 99 informative relatives.

Diarrheal disease as a cause of malnutrition.

Abstract: Although long associated with infectious diseases, malnutrition is recognized as a major effect of specific infections, especially those of the gastrointestinal tract. Synergistic exacerbation of infections and nutritional deficiency commonly begin with weaning, where the impact of repeated infections and possible monocyte mediator release may have an even greater effect on malnutrition of young children than that of deficient diets in many areas. Reviewed here are the detailed host alterations seen with specific enteric infections that lead to malnutrition. These include mucosal dysfunction, systemic metabolic responses, impaired intake, digestion and absorption, nutrient losses, altered immune responses, and ultimately, impaired growth, development, and nutrition. The tremendous health impact of diarrhea on both morbidity and mortality in many developing areas must be recognized and controlled along with correction of food shortages in order to improve the nutrition, growth, and survival of impoverished children.

Antibodies to Helicobacter pylori and pepsinogen levels in children from Costa Rica: comparison of two areas with different risks for stomach cancer.

Abstract: In children and adolescents from two areas of Costa Rica with contrasting gastric cancer risks, two factors suspected to be linked to the natural history of the disease were tested: serum antibodies to Helicobacter pylori and serum pepsinogen levels. One hundred fifty-five subjects from the high-risk area of Turrubares were compared to 127 from the low-risk area of Hojancha. No significant differences were found in the prevalence of IgG or IgA antibodies to Helicobacter pylori between the two regions. The prevalence of IgG was 65.8% in the high-risk area and 72.4 in the low-risk area, and that of IgA was 43% in both areas. The levels of pepsinogen, especially pepsinogen C, were significantly elevated in subjects with H. pylori antibodies in their serum. The mean levels of pepsinogen C in those negative, positive, and strong positive for H. pylori antibodies were 8.7, 14.3, and 21.1 ng/ml. These findings suggest that H. pylori-associated gastritis, predominantly of antral localization, is very prevalent in Costa Rican children and adolescents. Such gastritis might be associated with a high prevalence of intestinal metaplasia and a high gastric cancer risk in the inland, but not the coastal rural populations. H. pylori may therefore be an insufficient cause whose role in gastric carcinogenesis is contingent upon the presence of other factors.

Chirality and field activity of rhynchophorol, the aggregation pheromone of the American palm weevil

Abstract: The American palm weevil, Rhynchophoruspalmarum (L.) (Coleoptera: Curculionidae), is the major vector of Rhadinaphelenchus cocophilus, a nematode which causes red ring disease in oil and coconut palms throughout Central and South America [1]. Losses to this disease are significant, and its incidence has been correlated with weevil population density [1]. Trapping with insecticide-treated pieces of palm is practiced but traps lose their attractancy after a few days [2]. Therefore, the availability of a stable semiochemical to enhance trap attractancy would be of significant value in control of this pest. Recently, Rochat et al. [3] reported the identification and laboratory activity of a male-produced aggregation pheromone, 6-methyl-2(E)-hepten-4-ol (1) for this weevil. Weevils were collected on sawn sections of oil palm trunk in the Palma Tica plantations at Quepos and Coto 47, Costa Rica. They were maintained in laboratory cultures on fresh sugarcane or apples. Volatiles were collected by drawing air over 20 25 male or female R. palmarum in a Nalgene desiccator fitted with a charcoal filter at the inlet and a Porapak Q trap at the outlet. Aerations were carried out for 2 4 days at a flow rate of 85 1/h [4]. Trapped volatiles were extracted from the Porapak Q with pentane which was concentrated by distillation [4]. Gas chromatographic analysis conducted

The anthocerote chloroplast: a review

Abstract: SUMMARY This review covers previous data, together with new information from our laboratories, on the subject of the anthocerote chloroplast. Unlike all other archegoniates, most species of anthocerote have pyrenoids in their chloroplasts. The pyrenoid is the site of accumulation of the first enzyme in the C3 photosynthetic cycle, ribulose bispbosphate carboxylase/oxygenase. Unlike most algae, the hornwort pyrenoid is composed of distinct subunits, numbering up to several hundred. Pyrenoid morphology is quite variable among the genera in shape, fine structure, and distribution of inclusions. Another unique feature of the anthocerote chloroplast is the presence of thylakoids that connect adjacent granal stacks at right angles to the long axis of the granum (so-called channel thylakoids), resulting in a 'spongy’arrangement of the thylakoid system. The granal stacks of anthocerotes are like the‘pseudograna’of green algae because they lack the highly-curved end membranes typical of all other embryophytes. The channel thylakoids are enriched in photosystem (PS) I and the grana are enriched in PS II. The chloroplast envelope is a double membrane structure with regions of appression, much like that of other green plants. The apieal cell of the gametophyte contains chloroplasts similar to the mature chloroplasts of the thallus, although certain gametophytic tissues may contain underdeveloped plastids. Chloroplasts in cells around Nostoc colonies and in cells invaded by mycorrhizal fungi have thylakoids mainly in pairs, and small or absent pyrenoids. A number of similarly reduced plastids are noted in the placental cells at the sporophyte/gametophyte junction and in developing spores. The greatest reduction is observed in spermatid cell plastids, which at maturity consist of only a small starch grain surrounded by the envelope. Chromoplast-like organelles are found in the cells of the antheridial jacket in some genera; these contain numerous osmiophilic globules that are probably pigment aggregations. Colourless bead-like plastids occur in the rhizoids; these seem to develop by fragmentation of the single chloroplast in the rhizoid initials, concomitant with the loss of chlorophyll. Chloroplast division is a tightly controlled process and, in uniplastidic species, always occurs just before nuclear division, with the participation of a unique system of chloroplast-associated microtubules. The number of chloroplasts per cell is quite variable in some genera, although most species have but a single chloroplast in each cell of the gametophyte. Chloroplast shape is also variable from ellipsoidal, dumbbell-shaped, to irregular. These data indicate that the anthocerote chloroplast is unique among the embryophytes and are in line with the notion of an isolated position in the plant kingdom. Certain features of chloroplast morphology appear to be typical of certain genera and might prove useful in taxonomic decisions at the generic level.

Individual expression patterns of myotoxin isoforms in the venom of the snake Bothrops Asper.

Abstract: 1. 1. In order to investigate the distribution of myotoxin isoforms in the snake Bothrops asper, venoms from individual specimens were analyzed by a cathodic system for basic proteins under native conditions. 2. 2. The electrophoretic resolved at least five bands with slight differencesin mobility, corresponding to the fastest migrating proteins in the venom. The identity of the bands was confirmed by immunoblotting, using a rabbit anti-myotoxin serum. 3. 3. There were clear differences in the individual patterns of myotoxin isoform expression, both in specimens from the Altlantic and Pacific regions of Costa Rica. Some individuals possessed all five variants 4. 4. In agreement with previous reports, the venoms of ten newborn (less than 10 days of age) specimens completely lacked myotoxin bands, indicating on ontogenetic regulation in the expression of these toxins in B. asper. 5. 5. One of the bands, corresponding to the lysine-49 phospholipase myotoxin II, was the only isoform present in all individuals studied, suggesting a possible selective pressure for the conservation of this type of protein in the venom of B. asper.

A eficácia do antiveneno botrópico-crotálico na neutralização das principais atividades do veneno de Bothrops jararacussu

Abstract: A mionecrose e um dos efeitos causados pelo veneno de Bothrops jararacussu. Uma miotoxina com homologia estrutural a fosfolipase A2 (PLA2), mas sem atividade enzimatica, foi isolada desse veneno. O veneno de Crotalus durissus terrificus apresenta tambem atividade miotoxica, que vem sendo atribuida a crotoxina e a PLA2 (crotoxina B), o componente basico do complexo crotoxina. O veneno de Bothrops jararacussu apresenta tres proteinas, que tem identidade imunologica com a PLA2 da crotoxina. O presente trabalho comparou a eficiencia dos antivenenos polivalentes comerciais produzidos pelo Instituto Butantan - o antiveneno botropico (AB) e o antiveneno botropico-crotalico (AB/C) - na neutralizacao das atividades letal, hemorragica, coagulante e miotoxica do veneno de B. jararacussu. Os dois antivenenos neutralizaram de maneira semelhante a atividade hemorragica, mas o AB/C foi tres vezes mais potente que o AB em neutralizar a acao miotoxica e duas vezes mais potente na neutralizacao da letalidade e na acao coagulante do veneno de B. jararacussu. Os dados sugerem que a utilizacao do AB/C pode ser vantajosa no tratamento de pacientes picados por serpentes dessa especie

Once-weekly oral doses of fluconazole 150 mg in the treatment of tinea pedis.

Abstract: Seventy adult out-patients with tinea pedis participated in a multicentre open non-comparative study of the safety and efficacy of once-weekly doses of oral fluconazole 150 mg. A mean of 3 doses of fluconazole was administered; patients infected with Candida required an average of 2 doses compared to 3-4 doses in patients infected with other organisms. Clinical cure was obtained in 45 of 61 (74%) evaluable patients at the last post-treatment evaluation, with 15 patients being substantially improved and one patient failing clinically. At long-term follow-up, 28-30 days after the last dose was administered, 46 of 60 (77%) patients were clinically cured, 13 (22%) patients were improved and one patient failed. Trichophyton rubrum was isolated most frequently (47 of 60 mycologically evaluable patients). Mycological evidence of infection was eradicated from 52 of 60 (87%) patients post-treatment. At the long-term follow-up, infection was eradicated from 46 of 59 (78%) patients, persisted in five (8%) patients and relapsed in eight (14%) patients, six of whom were infected with T. rubrum and two of whom were infected with both T. rubrum and Candida. The number of doses received did not correlate with either the mycological response or relapse rates at long-term follow-up. The subgroup of 16 patients with infection of the sole of the foot, which is often considered to be more difficult to eradicate, responded similarly. Only 5 of 70 (7%) fluconazole-treated patients reported adverse effects, which were mild to moderate in severity, transient and did not result in discontinuation of therapy.(ABSTRACT TRUNCATED AT 250 WORDS)

Once-weekly oral doses of fluconazole 150 mg in the treatment of tinea corporis/cruris and cutaneous candidiasis

Abstract: Ninety-five adult out-patients with tinea corporis and/or tinea cruris participated in a multicentre open non-comparative study investigating the safety and efficacy of 1-4 once-weekly doses of oral fluconazole 150 mg. Trichophyton rubrum was isolated most frequently (67 of 86 mycologically evaluable patients). A mean of 2.6 doses of fluconazole was administered; patients infected with Candida albicans or Epidermophyton floccosum required an average of 2 doses compared to 3-4 doses in patients infected with other organisms. Clinical cure was obtained in 85 of 92 (92%) patients at the last post-treatment evaluation, with the remaining seven patients being substantially improved. At long-term follow-up, 28-30 days after the last dose, 80 of 91 (88%) patients were assessed as clinically cured, three (3%) patients were improved and eight (9%) patients failed. Among the long-term clinical failures, there was one diagnosis of tinea corporis (3% failure rate) and seven diagnoses of tinea cruris (12% failure rate). Mycological evidence of infection occurred in only 1 of 86 patients assessed at the last post-treatment follow-up. Mycological relapse occurred in nine (11%) patients at long-term follow-up; one patient was infected with Trichophyton mentagrophytes and eight patients were infected with T. rubrum. Relapse occurred in 2 of 29 (7%) patients with tinea corporis and eight of 57 (14%) patients with tinea cruris (one patient who relapsed had both tinea corporis and cruris). There was no correlation between the number of doses received and the mycological response or relapse rates at long-term follow-up.(ABSTRACT TRUNCATED AT 250 WORDS)

The influence of weather and microclimate on Dalbulus maidis (Homoptera: Cicadellidae) flight activity and the incidence of diseases within maize and bean monocultures and bicultures in tropical America

Abstract: Summary Mixed cropping systems in tropical America have been shown to be less prone than monocultures to damage from pathogens carried by insects. This finding formed the basis for a series of experiments conducted in Costa Rica to evaluate the hypothesis that mixed cropping systems create a physical environment that influences vector movement and consequently the spread of leafhopper-borne pathogens. The principle finding of the study is that both the mixture of plants and planting density have little influence on the spread of pathogens by Dalbulus maidis, an oligophagus leafhopper which prefers maize, within maize and bean single and mixed cropping systems. Leafhopper flight activity proved similar for high and low density monocultures and bicultures. The number of leafhoppers immigrating to and emigrating from a field appears dependent on the size of the field, not the density of maize plants. Single and mixed crops with the same density of maize plants were equally prone to damage by pathogens carried by leafhoppers. The lower percentage infection in high density than in low density maize treatments resulted from fewer vectors per plant in the former.

Microevolution of the Chibcha-speaking peoples of lower Central America: rare genes in an Amerindian complex.

Abstract: Articulo cientifico -- Universidad de Costa Rica, Instituto de Investigaciones en Salud. 1992. Este documento es privado debido a limitaciones de derechos de autor.

Angiostrongylus costaricensis natural infection in Vaginulus plebeius in Nicaragua.

Abstract: A study of 94 slugs, collected from urban and rural areas in and around Leon, Nicaragua, was carried out in order to confirm the role of Vaginulus plebeius as an intermediate host of Angiostrongylus costaricensis. Third-stage larvae of A. costaricensis were obtained from these molluscs. Some of these larvae were then orally inoculated into two laboratory-bred rats Sigmodon hispidus and adult worms of A. costaricensis were recovered two months later. The infection rate of these slugs ranged from 4 % in urban areas to 85 % in rural areas. These data suggest that contamination to man is a major risk especially in rural areas and that abdominal angiostrongyliasis could be a health problem in Nicaragua.

Los arrecifes coralinos del Refugio Nacional de Vida Silvestre Gandoca-Manzanillo, Limón, Costa Rica

Abstract: El Refugio Nacional de Vida Silvestre Gandoca-Manzanillo se localiza en la costa Caribe de Costa Rica, junto a la frontera con Panama. Los arrecifes coralinos del Refugio estan bien desmollados y relativamente poco alterados. Cinco tipos de arrecifes se encuentran alli: (a) rampa escaloanda distal, (b) arrecifes marginales (c) parches arrecifales, (ch) baocos carbonatados, y (d) arrecifes de base angosta, el cual se describe por primera vez para el Caribe. Una especie de coral, Meandrina meandrites y otra de octocoralario, Pterogorgia anceps, solamente se encontraron en el Refugio y en ningun otro arrecife de Costa Rica. Las dos especies principales fueron: Diploria strigosa, mayor porcentaje de cobertura del sustrato y Siderastrea siderea, mayor cantidad de colonias y segunda en cobertura. La importancia de estas dos especies vario con la profundidad: S . siderea fue mas abunante en aguas someras (menos de 8.5 m) y D. strigosa en aguas profundas. Los dos problemas ambientales principales en el Refugio fueron la sedimentacion y la extraccion de corales. Se recomienda que no se permita la recoleccion de corales u otros orgaismos arrecifales y que se proteja en forma efectiva los bosques costeros y de las cuencas de los rios y riachuelos locales.