A mass collection of Triatoma ryckmani (Hemiptera: Reduviidae)from Stenocereus eichlamii (Cactaceae)in the semiarid region of Guatemala

A population of 216 specimens of Stenocereus eichlamii (Cactaceae,Subfamily Cereoideae) was surveyed for Triatoma ryckmani (vector of Chagas disease)in a one hectare plot of semiarid habitat in Guatemala. Out of 44 plants that had dead and dry sections,24 plants had a total of 103 specimens of T.ryckmani .In comparison with other areas of Guatemala,T.ryckmani is well established in the semiarid ecosystem (Infestation index 54.5,density =2.3 and crowding index 4.3).The insects were mainly found (52.4%)in the dead portions of S.eichlamii 2.0 to 3.2 m above the ground (X2 =26.0,P<0.00001),followed by dry cactus sections between 3.2 and 5.0 m (35.9%).They were less frequent 0.2 to 2.0 m above the ground.A considerable proportion (75.7%)had no aparent blood in their digestive systems.To determine the presence of flagellates,43 of the bugs were dissected,but none were found.This is the first report on T.ryckmani population dynamics in this habitat

En Guatemala,en una hectárea de la región semiárida,se encontraron 216 cactus de Stenocereus eichlamii (Cactaceae),44 de ellos tenían alguna parte del tallo en condiciones secas.103 Triatoma ryckmani fueron halladas en 24 de esos 44 S.eichlamii .Una comparación de los índices entomológicos con otros vectores domiciliares de la enfermedad de Chagas en Guatemala,da la idea que T. ryckmani está bien establecida en el ecosistema semiárido (índice de infestación de 54.5,índice de densidad de 2.3 e índice de hacinamiento de 4.3).Los triatominos fueron hallados preferentemente en las partes muertas de S.eichlamii entre 2.0 a 3.2 m sobre el nivel del suelo (52.4%de triatominos colectados,X ²=26.0,p<0.00001),el siguiente entre 3.2 a 5.0 m (35.9%)y finalmente 0.2 a 2.0 m (11.6%). El 75.7 %estaba en condiciones de ayuno y 24.3 %estaban llenas de sangre.Para determinar la presencia de flagelados,43 T.ryckmani fueron disectadas, (primera evaluación de parasitemia en esta especie).Ningún flagelado fue hallado en estos triatominos.Este es el primer reporte de la dinámica poblacional de T.ryckmani en su hábitat silvestre

Effect of beta-lactamase inhibitors on minimum inhibitory concentration of ampicillin and amoxicillin for Staphylococcus aureus strains.

Seventy strains of Staphylococcus aureus isolated from the nasopharynx (80%), urinary tract (16%), skin (1 strain) and eyes (2 strains) of patients at the clinical laboratory "El eritrocito" were analyzed. Susceptibility to 12 antibiotics was tested by the method of Kirby-Bauer. Minimal inhibitory concentration (MIC) of ampicillin, ampicillin + sulbactam, amoxicillin and amoxicillin + clavulanic acid were determined by plate dilution. Percentages of resistance were: Penicillin and ampicillin (100%), ceftazidime (81.4%), erythromycin (68.6%), tetracycline (31.4%) trimethoprim-sulphametoxasol (25.7%), dicloxacillin and pefloxacin (12.8%), cefuroxime and cefotaxime (4.3%), gentamicin (2.8%), cephalothin (0%). All strains were resistant to three or more antibiotics, with higher percentages of resistance to four (31.4%), three (27.1%), five (21.4%) and six (12.9%) drugs. One strain was resistant to nine antibiotics and 5.9% were resistant to seven. 97.5% of the strains were beta-lactamase-positive. The MIC50 of ampicillin and amoxicillin was 500 micrograms/ml and the MIC90 were 1727 micrograms/ml and 2000 micrograms/ml, respectively. beta-lactamase inhibitors sulbactam and clavulanic acid reduced these values eightfold, except for the MIC50 of ampicillin + sulbactam whose reduction was sixteen fold. These results show that the combination of beta-lactamic + beta-lactamase inhibitor was more efficient than cephalosporins for killing these beta-lactamase-positive strains.

Potenciales evocados auditivos de tallo cerebral en rana catesbeiana / Brainstem auditory evoked responses on rana catesbeiana

Se estudió la sensibilidad de la vía auditiva a través del registro de los potenciales auditivos de tallo cerebral en 10 anfibios sanos de la especie Rana catesbiana. Las respuestas auditivas se efectuaron a 70, 50, 40 y 30 dB NA, en dos grupos de diferente peso. El primero de 17 a 27 gr y el otro grupo de 36 a 86.5 gr, los electrodos fueron insertados subcutáneamente y la estimulación fue por clicks en campo libre dentro de una cámara sonoamortiguada. A 70 dB las respuestas fueron de dos ondas en los primeros milisegundos, a 50 dB la onda II se separó en dos subcomponentes (IIa y IIb). El umbral electrofisiológico se estableció en 40 dB

Facilitation of the effect testosterone on male sexual behavior in rats deprived of REM sleep.

The possibility of rapid eye movement sleep deprivation (REMd) altering the effect of testosterone on masculine sexual behavior was investigated. Adult castrated male Wistar rats with no sexual experience were randomly assigned to the following three groups: REMd (using the water tank technique) for 7 days, large platform control for 7 days, and undisturbed sleep control. All subjects were treated with 1 mg testosterone propionate daily for 14 days. Masculine sexual behavior was assessed 3 consecutive days prior to steroid administration and was evaluated daily during the treatment. Frequencies and latencies of mounts, intromissions, and ejaculations, as well as the postejaculatory refractory period were recorded. One hundred percent of the REMd subjects presented mounts, intromissions, and ejaculations sooner than the control group. In almost all parameters, a clear facilitation of sexual activity was observed in the REMd group.