Estudo dos ventrículos cerebrais por ultrassonografia, na criança normal, nascida a termo, de 1 a 6 meses / Sonographic evaluation of cerebral ventricular system in healthy, full term infants aged 1-6 months

OBJETIVO: Estudo dos ventrículos cerebrais por ultrassonografia, com o objetivo de estabelecer de forma simplificada parâmetros para diagnóstico das dilatações ventriculares leves. MATERIAIS E MÉTODOS: Foram estudadas, prospectivamente, 105 crianças, normais, nascidas a termo, com um total de 181 exames realizados, mensalmente até os 6 meses, através da observação de dados morfológicos e medidas. As medidas efetuadas foram: índice ventrículo/hemisfério, diâmetro anteroposterior do corno anterior e do quarto ventrículo. RESULTADOS: Obtiveram-se média, desviopadrão e percentis de normalidade das medidas estabelecidas, em cada faixa etária. A pesquisa de halo anecoico nos dois terços posteriores do plexo coroide em plano coronal VI, para avaliação dos cornos temporal/posterior, foi ausente, e o terceiro ventrículo mostrou-se como uma fenda anecoica, menor que 1 mm, em plano coronal V em todas as crianças do estudo. CONCLUSÃO: Os achados morfológicos relacionados aos cornos temporal/posterior e ao terceiro ventrículo, associados ao percentil 95 das medidas como limite superior da normalidade, podem ser utilizados para diagnóstico simplificado de dilatações ventriculares leves.

OBJECTIVE: Study of the cerebral ventricular system by ultrasonography with the objective of establishing parameters for the diagnosis of mild ventricular dilatation. MATERIALS AND METHODS: Prospective study of 105 healthy, full term infants aged 1-6 months, submitted to monthly scans for morphological data evaluation and measurements of ventricle/ hemisphere ratio, and anteroposterior diameter of frontal horn and fourth ventricle. RESULTS: Normality mean, standard deviation and percentile were obtained for each age range. Negative results were observed in the search for anechoic halo surrounding the posterior two thirds of the choroid plexus on coronal section VI for evaluation of temporal/posterior horns, and the third ventricle was seen as an anechoic cleft < 1 mm on coronal section V in all of the evaluated infants. CONCLUSION: Sonographic findings related to temporal/posterior horns and third ventricle associated with the 95th percentile as upper limit of normality can be utilized as parameters for a simplified diagnosis of mild ventricular dilatation.

Antecedentes históricos de la neuroendoscopía argentina / Hisotircal antecedents of the argentine neuroendoscopy

El primer procedimiento neuroendoscópico fue realizado por Lespinasse en 1910 y Dandy, doce años después, manifestó la utilidad de estos procedimientos. En Argentina Roque Orlando y Manuel Balado, trabajando por separado, publicaron sus experiencias en 1931, dejando establecidas las indicaciones y potencialidades de la endoscopía. Durante el año 1932, un segundo informe de Balado, menciona que Payr, en 1919, había expresado la posibilidad de utilizar la endoscopía con fines experimentales, y comentó el trabajo publicado por Volkmann en 1923. En la década del '70, Conesa y Dillon comenzaron los estudios de neuroanatomía endoscópica en Argentina, arribando a conclusiones que hoy se consideran verdades absolutas. Finalmente, en el año 2001, los autores crearon el primer laboratorio de neuroanatomía endoscópica en el país

Entry, dispersion and differentiation of microglia in the developing central nervous system

Microglial cells within the developing central nervous system (CNS) originate from mesodermic precursors of hematopoietic lineage that enter the nervous parenchyma from the meninges, ventricular space and/or blood stream. Once in the nervous parenchyma, microglial cells increase in number and disperse throughtout the CNS; these cells finally differentiate to become fully ramified microglial cells. In this article we review present knowledge on these phases of microglial development and the factors that probably influence them.

Neuroendocrine regulation of salt and water metabolism

Neurons which release atrial natriuretic peptide (ANPergic neurons) have their cell bodies in the paraventricular nucleus and in a region extending rostrally and ventrally to the anteroventral third ventricular (AV3V) region with axons which project to the median eminence and neural lobe of the pituitary gland. These neurons act to inhibit water and salt intake by blocking the action of angiotensin II. They also act, after their release into hypophyseal portal vessels, to inhibit stress-induced ACTH release, to augment prolactin release, and to inhibit the release of LHRH and growth hormone-releasing hormone. Stimulation of neurons in the AV3V region causes natriuresis and an increase in circulating ANP, whereas lesions in the AV3V region and caudally in the median eminence or neural lobe decrease resting ANP release and the response to blood volume expansion. The ANP neurons play a crucial role in blood volume expansion-induced release of ANP and natriuresis since this response can be blocked by intraventricular (3V) injection of antisera directed against the peptide. Blood volume expansion activates baroreceptor input via the carotid, aortic and renal baroreceptors, which provides stimulation of noradrenergic neurons in the locus coeruleus and possibly also serotonergic neurons in the raphe nuclei. These project to the hypotlalamus to activate cholinergic neurons which then stimulate the ANPergic neurons. The ANP neurons stimulate the oxytocinergic neurons in the paraventricular and supraoptic nuclei to release oxytocin from the neural lobe which circulates to the atria to stimulate the release of ANP. ANP causes a rapid reduction in effective circulating blood volume by releasing cyclic GMP which dilates peripheral vessels and also acts within the heart slow its rate and atrial force of contraction. The released ANP circulates to the kidney where it acts through cyclic GMP to produce natriuresis and a return to normal blood volume.

Does plasma ANP participate in natriuresis induced by alpha-MSH?

Alpha-Melanocyte-stimulating hormone (alpha-MSH;0.6 and 3 nmol) microinjected into the anteroventral region of the third ventricle (AV3V) induced a significant increase in diuresis without modifying natriuresis or kaliuresis. Intraperitoneal (ip) injection of alpha-MSH (3 and 9.6 nmol) induced a significant increase urinary sodium, potassium and water excretion. Intraperitoneal (3 and 4.8 nmol) or iv (3 and 9.6 nmol) administration of alpha-MSH did not induce any significant changes in plasma atrial natriuretic peptide (ANP), suggesting that the natriuresis, kaliuresis and diuresis induced by the systemic action of alpha-MSH can be dissociated from the increase in plasma ANP. These preliminary results suggest that alpha-MSH may be involved in a gamma-MSH-independent mechanism of regulation of hydromineral metabolism.

La dominancia cerebral: un estudio de zurdera en un grupo de población mexicana / Cerebral dominance: a study of left-handedness in a group of Mexican population

El término "dominancia cerebral" sugiere que uno de los hemisferios es líder y el otro subordinado; sin embargo, la dominancia cerebral con respecto a todas las funciones psíquicas, se da con menor frecuencia de lo que podria suponerse. Entre las funciones en las que se manifiesta la dominancia cerebral, la más notable en el ser humano es la preferencia manual para realizar actividades motrices. Así, las personas se denominan diestras o zurdas; sin embargo, la lateralización de dichas funciones se halla entremezclada con evidencia de bilateralidad y una gran cantidad de diestros presentan zurdería oculta. Para obtener datos estadísticos de preferencia manual en la población mexicana se realizó una encuesta de 300 estudiantes universitarios y se encontró a 275 diestros, de los cuales sólo fueron confirmados 144 con pruebas complementarias; y 26 zurdos en los que sólo 5 fueron confirmados. Estos datos apoyan la hipótesis de que la lateralización parcial es más común que la total.

Normal parameters of ventricular system in healthy infants.

Six hundred healthy inborn newborns and infants upto the age of 18 months were studied. Cranial sonography was performed by real time 2D scanner with 5 MHz transducer and images were obtained through anterior fontanelle and temporo-squamal suture. Various parameters related to ventricular system were measured for different ages till the fontanelle remained open. These values will prove useful for diagnosing hydrocephalus at an early stage of the disease and also to find out the blocks at various levels in ventricular system.

Evolutionary origins of the reptilian brain: the question of putative homologues of dorsal ventricular ridge. An overview and proposal

The reptilian brain is characterized by a structure that bulges into the lateral ventricle, called dorsal ventricular ridge (DVR). The DVR was originally considered to be a part of the basal ganglia, although more recent studies indicate that it may correspond to the dorsal part of the hemisphere. The anterior portion of the DVR has several connectional and functional similarities with parts of the mammalian neocortex, for which reason it has been claimed that the two structures can be considered as homologues. In this article I review the evidence supporting and refuting homology of the DVR with different telencephalic structures of mammals, concluding that it is still early to unequivocally ascribe structural correspondences between the different components in the two vertebrate classes. However, a way out of the problem is suggested by comparing the embryonic position of DVR with that of lateral cortex in the reptilian hemisphere. The lateral cortex is considered to be quite comparable in reptiles and mammals, and hence may be a good marker for the original position of the DVR. If the DVR originates dorsal to lateral cortex, it may be considered comparable to parts of the mammalian neocortex, while if it develops in its same position or ventral to it, it may not correspond to the neocortex. Early embryological work indicated that the DVR develops in the same position as the lateral cortex, but arises as a late migration wave, after cells destined to lateral cortex are generated. In other words, instead of being interposed between dorsal and lateral cortices, the DVR may originate in a position overlapping with lateral cortex. If this alternative turns out to be the case, it may imply that the DVR arose de novo, through an extension of the ancestral period of neuroblast proliferation. As a consequence, there may be no structures comparable to it in other vertebrate classes. Finally, it is also proposed that, regardless of whether the DVR and the extrastriate neocortex can or cannot be considered phylogenetic homologues, some of the integrative functions performed by them might have a common evolutionary origin, that became localized in the reptilian DVR and in the mammalian extrastriate neocortex

Participation de alpha receptors in the neural control of food intake in pegeons

The effects of noradrenaline (NA) on food intake were investigated in 69 satiated (food ad libitum) adult pigeons (320-360 g). NA (30 nmol, N = 10, and 80 nmol, N = 12, in 1 µl NaCl) was injected into the right lateral ventricle. Both doses caused a significant increase in food consumption; the higher dose caused a more prolonged effect. The 30-nmol NA injection induced significant increases in the 1st (from 1.6 to 4.5 g) and 6th (19.4 to 25.9g) hours. The 80-nmol dose caused significant increases from the 1st to the 5th hour (1.6 to 6.8,4.4 to 8.7,7.1 to 10.8,10.1 to 14.1 and 14.9 to 21.0g). Previous intracerebroventricular administration of phentolamine (50 nmol, N = 12), but not of propranolol (100 nmol, N= 13) suppressed food ingestion increased by NA administration, with identical results to those of the control group (N = 22). These results indicate that central adrenergic synapses are likely to be involved in the mediation of food intake regulation

The effect of phentolamine on the pressor reponse to centrallly administered clonidine in rats

In the present study we investigae the effect of the previous injection of phentolamine (anonspecific alfa-adrenergic antagonist) into the lateral hypothalamus (LH) and lateral ventricle (LV) on the pressor and bradycardic responses produced by the injection of clonidine (an alfa-2 adrenergic agonist) into these same areas of conscious rats. The injections of clonidine into the LH produced pressor (39 ñ 5 and 38 ñ 3 mmHg, respectively) and bradycardic responses (-65 ñ 16 and -94 ñ 13 bpm, respectively). Previous injections of phentalamine into the LH or LV reduced the pressor response to clonidine injected into the same areas (DeltaMAP = 13 ñ 6 mmHg for LH and 1 ñ 3 mmHg for LV). No reduction was observed when clonidine was injected into the LV after the injection of phentalamine into the LH. No changes in bradycardic responses were observed after treatment with phentolamine. The present results show the participation of alfa-adrenergic receptors in the pressor response to centrally administered clonidine but not in the bradycardic reponse. The data also suggest that the pressor effect by the injection of clonidine into the LH is due to the activation of alfa-adrenergic receptors located specifically in this area. The pressor response after injection of clonidine into the LV and of phentolamine into the LH is due to the action of clonidine on other cerebral areas