[An ultrastructural evaluation of Pneumocystis carinii]. / Evaluación ultraestructural del Pneumocystis carinii.

The pneumocystis carinii (PNC) is a challenge, because its taxonomy has not been completely explained. PNC seems to be a chimera with fungal and parasitic characteristics. The objective of the present study is to analyze the different stages observed in PNC using transmission electron microscopy in order to correlate them with bibliographic reports regarding a possible taxonomic classification. The trophic stage was the form most frequently encountered in alveolar spaces and their organisms varying in size and shape from 6 to 20 microns. Cyst were round or oval, with diameters ranging between 4 and 12 microns, showing four intracystic bodies were individually limited by a membrane. Connections between the membrane of intracystic bodies and junctions between them and the inner cell membrane of the cyst wall were also observed. Our ultrastructural findings appear to be in agreement with several reports which considered PNC among the fungi, most likely related them to the non-gemating Ascomycetes.

[Importance of transmission electron microscopy in the diagnosis of a Venezuelan equine encephalitis outbreak in 1995 in the Venezuelan Guajira]. / Importancia de la microscopía electrónica de transmisión en el diagnóstico de la epidemia de encefalitis equina venezolana de 1995 en la Guajira Venezolana.

Transmission electron microscopy of the brain in 25 newborn mice was performed. Mice were intracerebrally inoculated with cultured VERO cells infected with VEE to be used as positive control, with samples of serum of cerebrospinal fluid from patients with clinical symptoms and signs of encephalitis, with serum from healthy patients or with serum from sick equines. Borate bovine albumin serum was also inoculated in some mice to be used as negative control. All samples were obtained during the epizootic and epidemic outbreak in the Venezuelan Guajira area, northern of Zulia State during October 1995. The ultrastructural study was blindly performed, however the presence of Togavirus particles were detected in 100% of the virologically positive cases. The usefulness, accuracy and speed of the employed methodology is stressed.