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Biomedical subjects

G Rojas

Publications and source records attributed to G Rojas.

At least 91 records · Page 5Linked to original sources
PubMed1985

Neutralization of proteolytic and hemorrhagic activities of Costa Rican snake venoms by a polyvalent antivenom.

The polyvalent antivenom produced at the Instituto Clodomiro Picado, Costa Rica, was tested for its capacity to neutralize proteolytic and hemorrhagic activities of ten Costa Rican crotaline venoms. In experiments with preincubation of venom and antivenom, the latter efficiently neutralized proteolytic activities of nine venoms, with ED50 ranging from 50 to 300 microliters antivenom/mg venom. The venom of Bothrops nummifer was neutralized less efficiently (ED50 = 760 microliters/mg.) Antivenom was also very effective in neutralizing hemorrhagic activity, having its lowest neutralizing ability against the venom of B. picadoi (ED = 430 microliters/mg) and its highest towards the venom of B. asper (Pacific region) (ED50 = 47 microliters/mg). There was a significant correlation between the ability of antivenom to neutralize proteolytic and hemorrhagic effects. In spite of the ability of antivenom to neutralize hemorrhage when incubated with venom prior to injection, hemorrhage was only partially neutralized when antivenom was administered i.v. at different time periods after envenomation. This suggests that the rapid development of local hemorrhage, instead of the absence of antivenom antibodies, is the explanation for the poor neutralization observed in these types of experiments.

Animals↗
PubMed1975

Aroapyrgus costaricensis, hydrobiid snail host of paragonimiasis in Costa Rica.

A small freshwater hydrobiid snail found in narrow shallow steams at various altitudes in Costa Rica is the intermediate host of Paragonimus mexicanus. Based on the morphology of its shell and soft parts the snail is assigned to the species Aroapyrgus costaricensis (Mörch). It is easily maintained in the laboratory; the female is ovoviviparous, carries up to 40 embryos in its brood pouch, and young-to-young cycle is about 10 weeks. Natural infection rates with rediae and cercariae of Paragonimus mexicanus are less than 1%, the majority of the naturally infected snails are of medium size (about 2 mm in height), but all sizes (ages) can be experimentally infected. The microcercous cercairae of P. mexicanus emerge from A. costaricensis in late afternoon and evening, about 2 months after exposure to the miracidia.

Animals↗
PubMedDate not supplied

The venom of Bothrops asper from Guatemala: toxic activities and neutralization by antivenoms.

Bothrops asper is responsible for approximately half of the snakebite envenomations in Central America. Despite its medical relevance, only the venom of Costa Rican populations of this species has been studied to some detail, and there is very little information on intraspecies variability in venom composition and toxicity. Venom of B. asper from Guatemala was analyzed by sodium dodecyl sulphate-polyacrylamide gel electrophoresis and two-dimensional gel electrophoresis, and its basic pharmacological activities were investigated with standard laboratory assays. Venom has lethal, hemorrhagic, myotoxic, edema-forming, coagulant, defibrinating and phospholipase A(2) activities, showing a similar toxicological profile to the one previously described for B. asper from Costa Rica. In addition, polyvalent antivenoms produced in Mexico and Costa Rica, and currently used in Guatemala, were tested for their ability to neutralize venom's toxic activities. Both antivenoms were effective against all effects studied, although the Costa Rican product showed higher potency against most activities tested and higher antibody titer against venom components, as determined by enzyme immunoassay. It is suggested that different dosage regimes should be considered when using these antivenoms in B. asper envenomations in Guatemala.

Animals↗