Showing papers by "University of Costa Rica published in 1988"

Oral Contraceptives and Cervical Cancer Risk in Costa Rica: Detection Bias or Causal Association?

Abstract: To examine the relationship between cervical cancer and oral contraceptive (OC) use, we analyzed data from a population-based, case-control study in Costa Rica. Women aged 25 to 58 years in whom cervical cancer was diagnosed and reported to the National Tumor Registry were examined as two separate case groups: invasive cervical cancer and carcinoma in situ (CIS). Controls were women aged 25 to 58 years identified through a national survey. Women who had used OCs had no increased risk of invasive cervical cancer compared with women who had never used OCs (relative risk, 0.8; 95% confidence interval, 0.5 to 1.3). Women who had used OCs had an increased risk of CIS compared with those who had never used OCs (relative risk, 1.6; 95% confidence interval, 1.2 to 2.2). However, further analyses indicated that this increased risk was confined to those who had recently used OCs. Also, the risk of CIS was not elevated in subgroups in which a history of cervical smears was not strongly linked to OC use. The elevated risk of CIS among OC users may therefore reflect a bias caused by enhanced detection of disease rather than a causal association.

Structural, stratigraphic, and petrologic aspects of the Arenal-Chato volcanic system, Costa Rica: Evolution of a young stratovolcanic complex

Abstract: Geologic mapping on a scale of 1:10000 and detailed stratigraphic studies of lava flows and tephra deposits of the Arenal-Chato volcanic system reveal a complex and cyclic volcanic history. This cyclicity provides insight into the evolution of magma batches during the growth of the andesitic volcanic system. The Arenal and Chato volcanoes have a central zone comprised of a lava armor and a distal zone comprised of a tephra apron. During Arenal's last two eruptive periods major craters formed near intersections of regional fractures at the lava armortephra apron transition. We suggest that such intersections are potential sites for future major explosions. The earliest rocks, i.e., the Chato lava flows, range in composition from basaltic andesite to andesite. These rocks, except for the andesitic domes of Chatito and La Espina, appear to have evolved from a common parental magma. The last active period of Chato volcano occurred 3550 B. P. The earliest known activity of Arenal volcano is 2900 B. P. Arenal lava flows have 54–56 wt% SiO2 and may be subdivided into a high-alumina group (HAG, Al2O3 = 20 wt%) and a low-alumina group (LAG, Al2O3 = 19 wt%). Compared to the HAG, the LAG also has smaller amounts of incompatible elements and higher amounts of FeO and MgO. Arenal tephra deposits were emplaced by Plinian-Sub-Plinian explosions occurring at 300±150-yr intervals. These deposits are compositionally zoned and alternate between dacite and basalt. The stratigraphy reveals an apparent magmatic cycle consisting of (a) dacitic-andesitic tephra, (b) HAG lava flows, (c) LAG lava flows, and (d) andesitic-basaltic tephra. This magmatic cycle is repeated four times during Arenal's history and is interpreted to have developed by the crystal fractionation and crystal redistribution of a single magma batch. The period of this cycle, and consequently the “life” of a magma batch, is about 800 years. If the cyclic pattern continues, a basaltic explosive phase may occur in the next 250 years.

Natural History and Behavior of a Primitively Social Wasp, Auplopus semialatus, and Its Parasite, Irenangelus eberhardi (Hymenoptera: Pompilidae)

Abstract: Two to eight females of a neotropical, primitively social wasp, Auplopus semialatus(Pompilidae), cooperatively build and maintain mud nests. Females capture non-web-building spiders as provisions for their offspring. Cohabiting females are usually tolerant of one another and defend the nest against natural enemies, including the cleptoparasitic wasp, Irenangelus eberhardi(Pompilidae). They often become intensely competitive, however, when a spider is brought to the nest. Auplopusfemales steal spiders from both uncapped and newly capped cells and eat the previous owner's egg. Many observations highlight the primitive level of sociality in this species, and the discussion relates these observations to those based on other primitively social wasps.

The oxidative metabolism of sparteine in the Cuna Amerindians of Panama: absence of evidence for deficient metabolizers.

Abstract: Articulo cientifico -- Universidad de Costa Rica. Instituto de Investigaciones en Salud, 1988

Production of monovalent anti - bothrops asper antivenom : development of immune response in horses and neutralizing ability

Abstract: A monovalent antivenom was produced by immunizing two horses with venom of the pit viper Bothrops asper (Ophidia: VipeIidae). Although development of the immune response against four toxic and enzymatic activities of the venom was similar in both horses during the the two thirds of the immunization schedule, antibody response in one of the horses reached much higher levels in the last part of the immunization. Immunoelectrophoretic analysis indicates that there were precipitating antibodies in the sera of these horses during all the stages of immunization. However, immunoprecipitation did not correlate with the ability of sera to neutralize toxic activities of B. asper venom. Monovalent antivenom was more effective than the commercially available polyvalent antivenom in the neutralization of Bothrops asper venom. On the other hand, despite the fact that it neutralizes lethal and hemorrhagic activities of the venoms of Lachesia muta and Crotalus durissus durissus, it was less effective than polyvalent antivenom in these neutralizations. Moreover, it does not neutralize defibrinating activity induced by these two venoms, whereas it neutralizes this effect in the case of B. asper venom. It is proposed that monovalent antivenom may be highly effective in the case of envenomations induced by Bothrops asper venom; its use in treating accidents by L. muta and C. durissus would be indicated only if polyvalent antivenom is not available. Results also demonstrate that it is important to monitor antibody response individually in horses being immunized for antivenom production, due to the conspicuous variability in the response of different animals.

Cancer in Costa Rica

Abstract: Articulo cientifico -- Universidad de Costa Rica. Isntituto de Investigaciones en Salud, 1989

Ficus microcarpa L., F. benjamina L. and other species introduced in the New World, their pollinators (Agaonidae) and other tig wasps

Abstract: The invasion of the Old World fig F. mieroearpa L. (section Conosycea) in U.S.A., Mexico and Central America by its Old World pollinator Parapristina verticillata is reported. Because of the size of the seedlings growing naturally in Florida, Honduras, and the State of Morelos, Mexico, and the fact that no seedlings were found in other parts of Mexico and El Salvador, we postulate that P. verticillata probably arrived to those areas within the last five years. It is probable that P. verticillata will move south invading all the tropical and subtropical countries where F. microcarpa is abundantly planted. Walkerella, a nonpollinating wasp was also found in Brazil and Florida inhabiting the syconia of F. microcarpa.The syconia of Old World F. benjamina L. (section Conosycea) in Costa Rica, were found pollinated by the New World Pegoscapus tristani. The pollinator of F. padifolia H.B.K. (section Americana). The syconia of Old World F. religiosa L. (section Urostigma) in Miami, Florida, were found to be pollinated by the symbiotic agaonid of the native F. aurea Nutt. Hybrid seedings were found growing naturally.Species of Ficus which evolved in different geographic areas, such as islands or continents could also evolve equally or similarly attracting synomones, which can confuse foreing agaonids and other sycophilous wasps when a species of fig is introduced.

Polychaetous Annelids from the Gulf of Nicoya, Costa Rica†

Abstract: Polychaetous annelids from a soft bottom community (1–46 m) were sampled from the Gulf of Nicoya, Costa Rica. A total of 125 species was identified, 120 from a faunistic study throughout the gulf and 78 species from a time study at four stations. The number of species from the Gulf was not as high as in some temperate areas. Temporal differences were slight compared to station differences. Twenty dominant species indicated three descriptive patterns: 1) Species with a marked seasonal peak and stable densities thereafter; 2) Species with a moderate seasonal peak and stable densities thereafter; and 3) Species with no discernible seasonal peak. Although 10 polychaete feeding guilds were identified, species from six feeding guilds were the dominant groups. The effect of the rainy season on polychaete opportunism and feeding guilds was discussed.

Maize Rayado Fino and Related Viruses

Abstract: Rayado fino (Spanish for fine stippling), from which maize rayado fino virus (MRFV) derives its name, describes the characteristic fine dots and small chlorotic stripes associated with the disease induced in maize (Zea mays ssp. mays L.) by this virus (Gamez, 1969, 1980a,b). MRFV (Gamez, 1980a) is the type member of the maize rayado fino virus group, the establishment of which was approved by the International Committee on Taxonomy of Viruses in 1985 (R. I. Hamilton, personal communication). Other viruses included as possible members of the group are the serologically related oat blue dwarf virus (OBDV) (Banttari and Zeyen, 1973) and the recently described Bermuda grass etched-line virus (BELV) (Lockhart et a1., 1984, 1985).

Cervical Cancer Risk and Use of Depot-Medroxyprogesterone Acetate in Costa Rica

Abstract: A nationwide case-control study was conducted in Costa Rica in 1984-85 to examine the association between depot-medroxyprogesterone acetate (DMPA) and cervical cancer. Cases restricted to women 25-58 years of age at the time of diagnosis were women with invasive squamous cell cancer (n = 149) or carcinoma in situ (CIS n=415) reported by the National Tumor Registry during 1982-84. The 764 controls were randomly selected during a nationwide household survey. On average the CIS cases were younger than controls; the invasive cases were older than controls. Both case groups were more likely than controls to be of low socioeconomic status to have become sexually active at a young age to report a history of a sexually transmitted disease or pelvic inflammatory disease and to report having 3 or more partners in their lifetime. Ever users of DMPA had a risk of CIS of 1.1 when compared with never users. Women who 1st used DMPA before age 30 had a CIS risk of 0.6 whereas users who began use after age 39 had a risk of 2.0. Both of these risk estimates were based on small numbers of users. Ever users of DMPA had a risk of invasive cancer of 1.4 when compared with never users but all estimates for invasive cancer were based on only 10 cases who reported use of DMPA. Few of the women had used DMPA for longer than 2 years.

Diversidad y abundancia diaria y estacional del zooplancton marino de la Isla del Caño, Costa Rica

Abstract: The plankton community at Cano Island might be a mixture between neritic and oceanic plankton, due to its proximity to the mainland sorne of its fauna could be associated to the surrounding reefs. The total zooplankton (indiv./m3 ) and copepods/tn3 show a relationship with local rainfall; with a peak of abundance during the dry season and a decrease toward the rainy season. Copepods are the dominant group (41-63%). Other groups present values below 10%in abundance lfish larvae, ostracods ana mysids were the most important). The number of taxa is higher during the dry season.

Morphological evidence by scanning electron microscopy of excretion of metacyclic forms of Trypanosoma cruzi in vector's urine

Abstract: Comparision by scanning electron microscopy (SEM) of Trypanosoma cruzi flagellates attached to the cuticle of the rectal gland of infected Dipetalogaster maxima nymphs, showed marked differences before amd after feeding. Before feeding numerous metacyclic trypomastigotes were observed among the abundant epimastigotes that formed the carpet of flagellates. On the other hand, in insects that were allowed to urinate for 24 hours after a meal, the metacyclics were scarce,indicating that they had been detached by the urine flow. An asymetric type of cell division, probably originating both an epi-and a trypomastigote, was occasionally observed. The occurrence of swellings at different levels of the flagella of epimastigotes suggests that secondary sites of attachment may be common.

Thirty-five years of Tropical biology: a quantitative history.

Abstract: Citation indices are unappropriated measures of scientific output and impact. For that reason, nonparametric statistics were preferred to analyze 35 years of publication on Tropical biology in the Revista de Biologia Tropical. The most frequent subjects are animal taxonomy, human biology -including medicine- ecology and animal behavior. Botany papers are less frequent and mainly deal with morphology and taxonomy. Applied studies are not predominant. In that period, only one case of unethical experimentation with humans was discovered in a paper of Mexican origin. The proportion of foreign institutions publishing in the journal has increased from 23% (1953-1963) to 50% in the last decade; similarly, the number of studies done in the Neotropics is on the rise. English and Spanish are equally frequent, although English is the basic language of ethology and evolution and Spanish predominantes in papers on animal morphology and parasitology. Most Costa Rican authors publish in Spanish, in contrast with many of their Latin American colleages. In recent years, there is a tendency to publish shorter papers written by more than one author. The Revista de Biologia Tropical, covered by 18 data bases, accounts for most exchanges and sales in the Universidad de Costa Rica and has worldwide distribution.

AIDS and HIV infection in Costa Rica – a country in transition

Abstract: Articulo cientifico -- Universidad de Costa Rica. Instituto de Investigaciones en Salud, 1988

Biología reproductiva de la cascabel centroamericana Crotalus durissus durissus (Serpentes: Viperidae) en Costa Rica

Abstract: In Costa Rica, rattlesnakes mate during the early dry season (December and January) and births occur in the early rainy season (May-July). Gestation is therefore about 6 months. The mean number of offspring is 22.9 and is significantly correlated with the size of the female. Newborn rattlesnakes are 27,543.0 cm in length and weight 11.4 - 46.3 g. They are relatively docile. Adult males are longer and heavier than females. Females seem to have their first litter when their size exceeds 120 cm.

A new cumacean (Crustacea) genus from beaches of Golfo de Nicoya, Costa Rica *

Abstract: Coricuma nicoyensis gen.et sp. nov . (Crustacea, Cumacea) is described from material collected during 1984 at the Punta Morales intertidal mud flat (> 30% silt + clay), Gulf of Nicoya (10° N, 85° W), Costa Rica. The exact placement of the new genus is problematical and for the present time is assigned to the Bodotriinae. This is the sixth cumacean described from the Pacific coast of the Americas between California and Tierra del Fuego.

Temperature profiles from Pos Crater Lake

Abstract: In 1984, we took part in an expedition to measure the temperature field and bathymetry of the acid lake (Figure 1) that has formed in the crater of Poas volcano, Costa Rica, since its last eruption in 1953. Obtaining these data was the first step in a long-range study planned by researchers at the Center for Geophysical Research, University of Costa Rica (San Jose, Costa Rica), and the College of Oceanography, Oregon State University (Corvallis). The study will eventually consider all aspects of fluid behavior in a volcanic lake that is heated or otherwise convectively driven by energy injected at the lake bottom. Evidence of convection is clearly visible on the surface of the Poas lake most of the time. Fumarole activity has been continuous since 1953. Phreatic explosions are quite frequent, varying from weak to strong, and the height of the ejected column varies from 1 to more than 500 m. One immediately useful result of the research would be an estimate of the heat transfer from sources within the conduit to the overlying water column. As far as geophysical fluid behavior goes, we are interested in the turbulent and diffusive processes by which heat and chemical species are transferred. We are especially interested in the impact on the density stratification of the density changes that occur as particulates settle downward through the fluid column. The stratification would otherwise be controlled by the turbulent and diffusive processes driven by thermochemical factors.

El guatuso de Palenque Matrgarita: su proceso de declinación

Abstract: El numero de lenguas indigenas americanas hablado en epoca precolombina en el territorio abarcado actualmente por el estado costarricense no parece haber sido muy superior al actual (Constenla 1983:28-30).

Morfología floral del achiote, Bixa orellana L. (Bixaceae)

Abstract: In a reinvestigation of the floral morphology of Bixa orellana, it was found that several organs such as stamens and gynoecium needed a new description. Anthers are folded, horseshoeshaped, with 4 locules and lateral dehiscence. The ovary is inferior and at maturity is raised by a gynophore. The flower has a netwotk of laticifers and gum channels.

Alotipo macho de Triatoma ryckmani Zeledón y Ponce, 1972

Abstract: The male allotype of Triatoma rickmani Zeledon y Ponce, 1972 is described. One specimen was found in Arado, Guanacaste province, Costa Rica. The insect was hiden under the bark of a guanacaste tree (Enterolobium cyclocarpum), approximately 1.5 m above ground.

Use of the temperate lichen Hypogymnia physodes (Parmeliaceae) to evaluate air pollution in the Tropics

Abstract: El liquen Hypogymnill physodes se usa en Europa como especie patron para evaluar la contaminacion atmosferica. Su transplante experimental de Reutlingen (Alemania Federal) a San Jose (Costa Rica), mostro que sobrevive al menos de tres y medio a diez meses y que reacciona al medio tropical adquiriendo las caracteristicas de coloracion de las especies nativas.