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Scanning ion-conductance microscopy allowed us to document an external Ca2+ dependent ATP driven volume increase (ATPVI) in capacitated human sperm heads. We examined the involvement of purinergic receptors (PRs) P2X2R and P2X4R in ATPVI using their co-agonists progesterone and Ivermectin (Iver), and Cu2+, which co-activates P2X2Rs and inhibits P2X4Rs. Iver enhanced ATPVI and Cu2+ and 5BDBD inhibited it, indicating P2X4Rs contributed to this response. Moreover, Cu2+ and 5BDBD inhibited the ATP-induced acrosome reaction (AR) which was enhanced by Iver. ATP increased the concentration of intracellular Ca2+ ([Ca2+]i) in >45% of individual sperm, most of which underwent AR monitored using FM4-64. Our findings suggest that human sperm P2X4R activation by ATP increases [Ca2+]i mainly due to Ca2+ influx which leads to a sperm head volume increase, likely involving acrosomal swelling, and resulting in AR.

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Transcranial magnetic stimulation (TMS) has been shown to be effective in modulating cerebral cortex activity. Most of the published controlled studies have reported that left temporoparietal area stimulation with 1 Hz frequencies has managed to improve auditory hallucinations at least partially and transiently in patients suffering from schizophrenia. These stimulation parameters have been demonstrated to be useful in otologic patients with tinnitus sensation. The clinical relevance of these findings has already been discussed. However, in spite of the clinical benefit of TMS for these or other patients, it is revealing new data and new questions about the neurobiological basis of mental disorders. For example: which is the common substrate in tinnitus and auditory hallucinations that could explain such a therapeutic coincidence? In this work we present two representative clinic cases and we discuss this question.

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La estimulación magnética transcraneal (EMT) se ha demostrado capaz de modular la actividad de la corteza cerebral. La estimulación del área temporoparietal izquierda con frecuencias de 1 Hz ha conseguido mejorar, al menos de forma parcial y transitoria, las alucinaciones auditivas de pacientes con esquizofrenia en la mayoría de los estudios controlados publicados. Lo mismo podemos decir de dichos parámetros de estimulación aplicados a pacientes otológicos con sensación de tinnitus. Se discute todavía la relevancia clínica de estos hallazgos. Sin embargo, aparte del beneficio clínico que pueda aportar en un futuro la EMT a estos u otros pacientes, nos está aportando nuevos datos y nuevas preguntas sobre las bases neurobiológicas de los trastornos mentales. Por ejemplo: ¿qué tienen en común el tinnitus y las alucinaciones auditivas para semejante coincidencia terapéutica? En este trabajo se presentan dos casos clínicos ilustrativos y se discute acerca de la pregunta formulada (AU)

Transcranial magnetic stimulation (TMS) has been shown to be effective in modulating cerebral cortex activity. Most of the published controlled studies have reported that left temporoparietal area stimulation with 1 Hz frequencies has managed to improve auditory hallucinations at least partially and transiently in patients suffering from schizophrenia. These stimulation parameters have been demonstrated to be useful in otologic patients with tinnitus sensation. The clinical relevance of these findings has already been discussed. However, in spite of the clinical benefit of TMS for these or other patients, it is revealing new data and new questions about the neurobiological basis of mental disorders. For example: which is the common substrate in tinnitus and auditory hallucinations that could explain such a therapeutic coincidence? In this work we present two representative clinic cases and we discuss this question (AU)

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Components with phospholipase A2 activity were isolated by gel filtration and cationic exchange chromatography from the venom of Bothrops asper snakes from Chiriguaná, Colombia (9°22´N; 73°37´W). Five fractions were obtained by the gel filtration, and PLA2 activity was found in fraction 3 (F3). In the cationic exchange chromatography, F3 showed eight components with PLA2 activity. Six of these components appeared as one band in polyacrylamide gel electrophoresis (SDS-PAGE). Fractions II and VII exhibited an optimal activity at pH 9 and 52ºC. The optimum calcium concentration for fraction II was 48 mM and for fraction VII, 384 mM. Both fractions showed thermal stability. Fraction II was stable at pH values between 2.5 and 9, and fraction VII, between 2.5 and 8. The Michaelis Menten constant (K M) was 3.5x10-3 M for fraction II and 1.6x10-3 M for fraction VII. The molecular weight was 16,000 Dalton for fraction II and 17,000 Dalton for fraction VII. Both isoenzymes did not show any toxic activity (DL50) at 5.3 and 4 µg/g. The two fractions showed different kinetic constant (K M), calcium requirement, and substrate specificity for haemolytic activity.

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La fosfolipasa A2 (PLA2) fue purificada a partir de vene-no de serpiente de Bothrops atrox (Sensu lato) de Chiriguaná (Colombia) por cromatografía de exclusión sobre Sephadex G-75, de donde se obtuvieron cinco frac-ciones, una de ellas con actividad fosfolipasa A2. Des-pués de pasarla por una columna de intercambio catiónico Mono S, donde se separaron ocho fracciones con activi-dad PLA2, ésta se midió usando el método hemolítico. La electroforesis en gel de poliacrilamida en condiciones desnaturalizantes, mostró pesos moleculares entre 16.000 y 17.000 para las ocho fracciones, seis de las cuales pre-sentaron una sola banda.

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