Seasonal variations of female aggressiveness and population dynamics of Culex quinquefasciatus Say 1823 in Abidjan (Republic of C?te d'Ivoire)

Seasonal variations of Culex quinquefasciatus aggressiveness were studied in Abidjan where this mosquito is very harmful. Abidjan is crossed from East to West by the Ebrié lagoon, which is a vast expanse of brackish water (about 566 km2). In the North of this expanse of water lay continental plateaux and in the South lay low-plateaux. The city is composed of 10 districts, most of which are situated on the continental plateaux. Culex quinquefasciatus adult populations were caught monthly in 1989 on human bait traps in Abidjan 10 districts, one study place was located in each district. Captures took place outside the houses, in the dusk and during the first part of night, that is to say between 4 p.m. and 1 a.m. In Abidjan, Culex quinquefasciatus population density varies considerably within the city area. In the areas where the species is numerous, a high percentage of it seems to be developing all year through from breeding places which are, in most cases, permanent. Besides, the aggressiveness seasonal cycle which was registered in the above mentioned areas is particularly diversified.     

Ilioinguinal block dissection for malignant melanoma

A retrospective analysis of 41 patients treated for metastatic inguinal lymph node malignant melanoma is presented: 16 underwent inguinal node excision and 25 ilioinguinal node excision. The two groups were well matched for age, sex and other characteristics. The mean time in hospital (inguinal 20 days, ilioinguinal 18 days) and the complication rates (inguinal, ten of 16 patients, ilioinguinal, 13 of 25) were similar in each group. The incidence of groin relapse, defined as the development of symptomatic melanoma in the region of the inguinal or iliac node basins following block dissection, was lower after ilioinguinal block dissection (inguinal, three patients; ilioinguinal, none). Histological examination demonstrated a high proportion of iliac node involvement (13 of 25 patients), even in those with a single mobile inguinal lymph node clinically and no clinical or computed tomographic evidence of iliac node involvement. This supports the value of ilioinguinal block dissection and suggests that the associated morbidity need not be greater than that associated with inguinal clearance alone.     

Structural destabilization of synaptosomal particles by lysis and sequential chemical treatments

Synaptosomes from rat brains were subjected to a sequence of treatments: osmotic lysis, buffered saline wash, nonionic detergent, EGTA and EDTA. After each treatment, particulate samples were fixed in 2% glutaraldehyde-1% formaldehyde and centrifuged to form pellets which were then processed for and examined by electron microscopy. Five morphological classes of synaptic particle were defined in terms of character and presence of synaptic vesicles, flocculent and stranded material, designated as intervesicular scaffolding (IVS), and presynaptic membrane. During osmotic lysis, the presynaptic compartment was altered by loss of most, but not all, small synaptic vesicles, by increase in proportion of large vesicles, and by disappearance of the presynaptic densities. The retention of vesicles was interpreted in terms of IVS struts interconnecting anchorage sites on synaptic vesicles and the presynaptic junctional membrane. Treatment of lysed synaptosomes with nonionic detergent or EGTA resulted in loss of vesicles and IVS from the junctional region in most particles. The apposition of pre-and postsynaptic junctional membranes along the synaptic cleft was disrupted more by EGTA than by detergent. The final result of the sequential treatments was a sediment containing a high proportion of synaptic particles, about half of which had lost their presynaptic junctional membranes.