Neutralization of bitis parviocula (Ethiopian mountain adder) venom by the south african institute of medical research (SAIMR) antivenom

BACKGROUND: The Ethiopian mountain adder (Bitis parviocula) is a viperid known only from a few locations in southwestern Ethiopia. METHODS: a total of 30 µg of B. arietans and B. parviocula venoms were run on a 10-20% Tricine gel. To assay lethality dose fifty (LD50), five groups of eight mice for each venom were used. Hemorrhagic activity for crude venom was tested. Fibrinogenolytic activity of crude venom was measured using (2.5 mg/mL) of fibrinogen solution and (0.03 mg/mL) of crude venom. Gelatinase activity of the venom was tested on a Kodak X-OMAT TM film. Crude venoms of B. parviocula and B. arietans were tested for their abilities to affect clotting time, clotting rate and platelet function on whole human blood. RESULTS: The (SAIMR) antivenom was confirmed in this study to neutralize the lethal activity of venom from Bitis parviocula. The ED50s of SAIMR antivenom on B. parviocula and B. arietans neutralized half of 18.2 and 66.7 mg of venom, respectively. The hemorrhagic activities (MHDs) of B. parviocula and B. arietans were 0.88 and 1.7 µg, respectively. Bitis arietans and B. parviocula venoms degradated α and β chains at different times. The γ chains remained unaffected. Bitis parviocula venom did not exhibit gelatinase activity, while B. arietans had a MGD of 6.9 µg. At 3 mg/mL, the crude venoms of B. parviocula and B. arietans did not significantly affect clotting time or clotting rate. CONCLUSIONS: The SAIMR antivenom is very effective in neutralizing the venom of B. parviocula and should be considered in treating envenomations by these snakes.

MODELES DES TRANSFERTS RADIATIFS A L'INTERIEUR DES COUVERTS VEGETAUX LES SOLUTIONS ANALYTIQUES

Cette étude décrit la modélisation mathématique des transferts radiatifs en milieu végétal, en focalisant l'attention sur le régime du rayonnement solaire au sein des couverts végétaux homogènes. Le rayonnement solaire est traité en quatre composantes principales: rayonnement primaire et complémentaire, chacune de ces parties étant constituée des composantes directe et diffuse. On a présenté, dans un contexte assez général, les équations différentielles ou les systèmes d'équations différentielles qui gouvernent les différents processus de interaction rayonnement-végétation, et des solutions analytiques sont proposées pour les différentes composantes.

Effects of anthropogenic impacts on benthic macroinvertebrates assemblages in subtropical mountain streams

The nature of the riparian and surrounding landscape has been modified by anthropogenic activities, which may subsequently alter the composition and functional structure of macroinvertebrate assemblages. The effect of these changes on function of benthic fauna is difficult to assess due to the scarce knowledge on functional structures in tropical streams. In this study we evaluate whether sites impacted and unimpacted by anthropogenic alterations differed in assemblage composition and density, richness and diversity of each functional feeding group. The selection of the sites was related to their distinct riparian characteristics, following the QBRy riparian quality index. Collector-gatherer was the dominant functional feeding group, comprising 91% of total density, whereas the proportion of shredders was very low, representing less of 0.5% of total density. Asemblage composition of macroinvertebrates differed between impacted and unimpacted sites. Predators were dominant in taxa number, representing about 60% of total taxa richness. In addition, the diversity and richness of collector-gatherers differed significantly between degraded and unimpacted sites, reflecting the sensitivity of this group to environmental changes and the utility to be used in the assessment of anthropogenic modifications. The results of this study reinforce the idea that riparian corridor management is critical for the distribution of macroinvertebrate assemblages as well as functional organization of lotic streams.

Occurrence of Hirudinea species in a post urban reach of a Patagonian mountain stream

Temporal (May 2005 to February 2006) and habitat distribution (pools and riffles) of Hirudinea species was analyzed at a post urban reach from Esquel stream (Chubut province, Patagonia, Argentina). Site was located 5.7 km downstream a Waste Treatment Plant. Mean values of nutrients: ammonia, nitrates and soluble reactive phosphate, as well water conductivity, turbidity and total suspended solids indicated physical and organic pollution. Leeches assemblage was composed by the glossiphonids: Helobdella scutifera Blanchard, 1900, H. michaelseni (Blanchard, 1900), H. simplex (Moore, 1911), Helobdella sp., H. hyalina Ringuelet, 1942, H. obscura Ringuelet, 1942 and the semiscolecid Patagoniobdella variabilis (Blanchard, 1900). From these H. hyalina and H. obscura are new records for Chubut province. Helobdella hyalina (810 ind.m-2) and H. simplex (465 ind. m-2) clearly dominated the assemblage at the reach. Only H. simplex displayed a spatial preference being significantly more abundant in pools than in riffle habitats (p<0.001). Species recruitment occurred mostly at September, December and March when juveniles were very abundant. Although several species of Helobdella were able to live in the disturbed section of the stream, only H. simplex and H. hyalina sustained large populations at the site and can be considered as tolerant to organic enrichment. This information is valuable to future studies on stream condition assessment in mountainous areas in Patagonia, and in other areas in which these species are present.

Leishmaniose en Bolivie: IV. Le chien dans les cycles des leishmanioses en Bolivie

En Bolivie le chien domestique est impliqué dans le cycle de la leishmaniose viscérale (Leishmania (Le.) chagasi) das les Yungas (alt. 1,000-2,000 m) et aussi dans le cycle de la leishmaniose tégumetaire (Le. (V.) braziliensis) dans l'Alto Beni (alt. 400-600 m). Mais il joue un rôle différent dans les deux cycles. Il est le prencipal résevoir, peut-être l'unique de Le. (Le.) chagasi dans les Yungas, et la source de contamination de l'home. Dans l'Alto Beni, il n'est seulement qu'une victime, comme l'home, de Le. (V.) braziliensis, dont le réservoir reste inconnu, les soupçons se portant sur des mammifères sauvages.