Isolation of Paracoccidoides brasiliensis from armadillos (Dasypus novemcinctus) captured in an endemic area of paracoccidioidomycosis

Paracoccidioides brasiliensis, the causative agent of paracoccidioidomycosis (PCM), was first isolated from the Amazonian gerion where the mycosis is uncommon. In the present study, we report on the high incidence of PCM infection in armadillos from a hyperendemic region of the disease. Four nine-banded armadillos (Dasypus novemcinctus) were captured in the endemic area of Botucatu, Sao Paulo, Brazil, killed by manual cervical dislocation and autopsied under sterile conditions. Fragments of lung, spleen, liver and mesenteric lymph nodes were precessed for histology, cultured on Mycosel agar at 37ºC, and homogenized for inoculation into the testis and peritoneum of hamster. The animals were killed from week 6 to week 20 postinoculation and fragments of liver, lung, spleen, testis, and lymph nodes were cultured on brain heart infusion agar at 37ºC. Paracoccidioides brasiliensis was isolated from three armadillos both by direct organ culture and from the liver, spleen, lung, and mesenteric lymph node hamster. In addition, one positive armadillo presented histologically proven PCM disease in a mesenteric lymph node. The three aramdillos isolates (Pb-A1, Pb-A2, and Pb-A4) presented thermodependent dimorphism, urease activity, and casein assimilation, showed amplification of the gp43 gene, and were highly virulent in intratesticulary inoculation hamster. The isolates expressed the gp43 glycoprotein, the immunodominant antigen of the fungus, and reacted with a pool of sera from PCM patients. Taken together, the present data confirm that armadillos are a natural reservoir of P. brasiliensis and demonstrate that the animal is a sylvan host to the fungus

Audiosensitization and desensitization control seizure susceptibility in hamsters

This study demonstrates that a brief exposure [90 seconds] to sound of door bell at an intensity of 95 decibels during a critical period in development of hamster induces seizure susceptibility in a nonsusceptible strain. Repeated stimulation at specific intervals induced an anticonvulsant state against the spontaneous sizure in epileptic hamsters. The critical age of audiosensitivity was found to be from 28 to 31 days. The increase of the age with increase of the interval between stimulation and test was associated with a decrease in seizure susceptibility

Effect of extra-weight loading and aerobic running training on contractile properties of gastrocnemius muscle in hamsters

The effect of extra-weight loading was studied using Syrian [CHF 148] hamsters. Thirty animals were divided into three groups: sedentary control [SC], sedentary extra-weight loaded [SEW] and extra-weight loaded and aerobic running training [EWAT]. The animals were made to carry extra weight [15% of body weight] continuously for 8 weeks. Additionally, aerobic running training was provided to the EWAT group with gradually increased loading. Contractile characteristics of gastrocnemius muscles were determined in vitro. Means of body mass and gastrocnemius mass were compared. Body mass and gastrocnemius mass increased significantly in the SEW group. Twitch tension was enhanced in both the SEW and EWAT groups. Tetanic tension was significantly higher only in the EWAT group. Compared to the SC group, time to peak and half relaxation time significantly increased in gastrocnemius muscles of SEW hamsters and decreased in EWAT hamsters. The tension values for development during tetanic contraction and decline during relaxation were considerably higher for the EWAT group. Similar values were obtained for the SC and SEW groups. The findings indicate that, whereas constant extra-weight loading may increase muscle mass, it decreases muscle contraction speed and does not affect muscle tension. In contrast, constant extra-weight loading combined with aerobic running training enhances the contractile characteristics of muscles

Relationship between sperm concentration and the rate of fertilization in vitro of golden hamster eggs

El éxito de la fecundación depende de una interacción gamética adecuada. La evidencia disponible sugiere que el espermatozoide atravesará la zona pelúcida sólo cuando se asocia con ella en foram oblicua a través de sus bordes dorsal/ventral y anterior. Esta asociación es mediada por receptores espermáticos presentes en el borde externo de la zona pelúcida. La eficiencia de la penetración espermática podría estar asociada con la posibilidad que el espermatozoide pueda establecer ese tipo de asociación. Esta hipótese de trabajo se ensayó con un estudio realizado in vitro en el cual ovocitos de hamster con zona pelúcida se inseminaron con espermatozoides capacitados a concentraciones de 1.000, 24.111 y 48.000 espermatozoides/µl. Los resultados mostraron que al aumentar la concentración espermática, la tasa de fecundación bajó de un 97.7%, con la concentración espermática más baja, a un 63% con la concentración más alta. De la misma manera se observó que el promedio de 2,77 cuando se usó la concentració más alta. En ambos casos las diferencias fueron estadísticamente significativas (P < 0.001). Las observaciones con el microscopio electrónico de barrido mostraron que al usar concentraciones bajas de espermatozoides, éstos se asociaban con la zona pelúcida por sus bordes dorsa/ventral y anterior. Al usar concentraciones altas de espermatozoides, éstos se asociaban a través de su borde anterior. En el primer caso la asociación resultaba en una penetración exitosa, en cambio en el segundo caso, muchos espermatozoides eran incapaces de cruzar la zona