Anatomical and functional study of the cuneiform nucleus: A critical site to organize innate defensive behaviors.

The cuneiform nucleus (CUN) is a midbrain structure located lateral to the caudal part of the periaqueductal gray. In the present investigation, we first performed a systematic analysis of the afferent and efferent projections of the CUN using FluoroGold and Phaseolus vulgaris leucoagglutinin as retrograde and anterograde neuronal tracers, respectively. Next, we examined the behavioral responses to optogenetic activation of the CUN and evaluated the impact of pharmacological inactivation of the CUN in both innate and contextual fear responses to a predatory threat (i.e., a live cat). The present hodologic evidence indicates that the CUN might be viewed as a caudal component of the periaqueductal gray. The CUN has strong bidirectional links with the dorsolateral periaqueductal gray (PAGdl). Our hodological findings revealed that the CUN and PAGdl share a similar source of inputs involved in integrating information related to life-threatening events and that the CUN provides particularly strong projections to brain sites influencing antipredatory defensive behaviors. Our functional studies revealed that the CUN mediates innate freezing and flight antipredatory responses but does not seem to influence the acquisition and expression of learned fear responses.

The anterior cingulate cortex and its role in controlling contextual fear memory to predatory threats.

Predator exposure is a life-threatening experience and elicits learned fear responses to the context in which the predator was encountered. The anterior cingulate area (ACA) occupies a pivotal position in a cortical network responsive to predatory threats, and it exerts a critical role in processing fear memory. The experiments were made in mice and revealed that the ACA is involved in both the acquisition and expression of contextual fear to predatory threat. Overall, the ACA can provide predictive relationships between the context and the predator threat and influences fear memory acquisition through projections to the basolateral amygdala and perirhinal region and the expression of contextual fear through projections to the dorsolateral periaqueductal gray. Our results expand previous studies based on classical fear conditioning and open interesting perspectives for understanding how the ACA is involved in processing contextual fear memory to ethologic threatening conditions that entrain specific medial hypothalamic fear circuits.

The rostrodorsal periaqueductal gray influences both innate fear responses and acquisition of fear memory in animals exposed to a live predator.

A few studies have evaluated the behavioral roles of the periaqueductal gray (PAG) in animals facing ethologically relevant threats. Exposure to a live cat induces striking activation in the rostrodorsal and caudal ventral PAG. In the present investigation, we first showed that cytotoxic lesions of the rostrodorsal and caudal ventral PAG had similar effects on innate fear responses during cat exposure, practically abolishing freezing and increasing risk assessment responses. Conversely, rostrodorsal PAG lesions but not caudal ventral lesions disrupted learned contextual fear responses to cat exposure. Next, we examined how muscimol inactivation of the rostrodorsal PAG at different times (i.e., during, immediately after and 20 min after cat exposure) influences learned contextual fear responses, and we found that inactivation of the rostrodorsal PAG during or immediately after cat exposure but not 20 min later impaired contextual fear learning. Thus, suggesting that the rostrodorsal PAG is involved in the acquisition, but not the consolidation, of contextual fear memory to predatory threat. Notably, the dosolateral PAG contains a distinct population of neurons containing the neuronal nitric oxide synthase (nNOS) enzyme, and in the last experiment, we investigated how nitric oxide released in rostrodorsal PAG influences contextual fear memory processing. Accordingly, injection of a selective nNOS inhibitor into the rostrodorsal PAG immediately after cat exposure disrupted learned contextual responses. Overall, the present findings suggest that the acquisition of contextual fear learning is influenced by an optimum level of dorsal PAG activation, which extends from during to shortly after predator exposure and depends on local NO release.

Revealing a Cortical Circuit Responsive to Predatory Threats and Mediating Contextual Fear Memory.

The ventral part of the anteromedial thalamic nucleus (AMv) receives substantial inputs from hypothalamic sites that are highly responsive to a live predator or its odor trace and represents an important thalamic hub for conveying predatory threat information to the cerebral cortex. In the present study, we begin by examining the cortico-amygdalar-hippocampal projections of the main AMv cortical targets, namely, the caudal prelimbic, rostral anterior cingulate, and medial visual areas, as well as the rostral part of the ventral retrosplenial area, one of the main targets of the anterior cingulate area. We observed that these areas form a clear cortical network. Next, we revealed that in animals exposed to a live cat, all of the elements of this circuit presented a differential increase in Fos, supporting the idea of a predator threat-responsive cortical network. Finally, we showed that bilateral cytotoxic lesions in each element of this cortical network did not change innate fear responses but drastically reduced contextual conditioning to the predator-associated environment. Overall, the present findings suggest that predator threat has an extensive representation in the cerebral cortex and revealed a cortical network that is responsive to predatory threats and exerts a critical role in processing fear memory.

A role for the anteromedial thalamic nucleus in the acquisition of contextual fear memory to predatory threats.

Previous studies from our group have shown that cytotoxic lesions in the ventral portion of the anteromedial thalamic nucleus (AMv), one of the main targets of the hypothalamic predator-responsive circuit, strongly impairs contextual fear responses to an environment previously associated with a predator. The AMv is in a position to convey information to cortico-hippocampal-amygdalar circuits involved in the processing of fear memory. However, it remains to be determined whether the nucleus is involved in the acquisition or subsequent expression of contextual fear. In the present investigation, we addressed this question by inactivating the rat AMv with muscimol either prior to cat exposure or prior to exposure to the cat-related context. Accordingly, AMv pharmacological inactivation prior to cat exposure did not interfere with innate fear responses, but it drastically reduced contextual conditioning to the predator-associated environment. On the other hand, AMv inactivation prior to exposure to the environment associated with the predator threat did not affect contextual fear responses. The behavioral results were further supported by the demonstration that AMv inactivation prior to cat exposure also blocked the activation of sites critically involved in the expression of anti-predatory contextual defensive responses (i.e., the dorsal premammillary nucleus and the dorsolateral periaqueductal gray) in animals exposed to the predator-associated context. The AMv projections were also examined, and the results of this investigation outline important paths that can influence hippocampal circuitry and raise new ideas for anterior thalamic-hippocampal paths involved in emotional learning.

Região posterior da maxila: atualizando conceitos anatômicos com o avanço da tecnologia de superfícies. Relato de caso clínico / The posterior maxilla: An update of anatomical notions based on advances in endosseousimplant surface technology. A case report

Objetivo: desde o início da especialidade Implantodontia, o tratamento reabilitador por meio de implantes na região posterior de maxila foi considerado um grande desafio para o profissional. As limitações das técnicas e materiais empregados geraram conceitos errôneos, principalmente quanto às definições de classificações ósseas, criando um conceito de osso pobre, que condizia com o nível elevado de insucessos de tratamentos realizados com superfícies de implantes pouco evoluídas. Revisando a literatura a respeito da origem embriológica tecidual da maxila e sua anatomia, observa-se a grande capacidade regenerativa de ossos medulares que são ricos em células mesenquimais. Métodos: destaca-se, nesse relato de caso clínico, a falha de um implante de superfície maquinada, fixado por técnica de osteotomia em região de primeiro molar de maxila, que foi substituído por implante de superfície SLA (sand-blasted, large-grit, acid-etched), com acompanhamento de taxa de sobrevivência de cinco anos. Resultados: avaliações clínica e radiográfica, em períodos de revisão semestral, foram realizadas, demonstrando a estabilidade de osseointegração do implante e a biocompatibilidade tecidual, além da funcionalidade da prótese realizada. Conclusão: em associação à vasta literatura científica que mostra a evolução tecnológica das superfícies de implantes que estimulam a transformação das células mesenquimais em osteoblastos, gerando, com isso, a osseointegração em períodos curtos de tempo, podemos sugerir que a região posterior de maxila se transforma em uma proposta previsível e segura de reabilitação por implantes.

Objective: Fixed implant-supported rehabilitation of the posterior maxilla is a challenge to dental professionals. Limitationsof technique and material have established wrong concepts, especially with regard to bone classification. Forinstance, the concept of poor-quality bone has been associated with high rates of therapeutic failure because of implantswith poorly evolved surfaces. A literature review on the embryological origin of tissues and the anatomy of the maxillahighlight the high regenerative ability of trabecular bone, which is rich in mesenchymal cells. Methods: The presentreport describes a case of failure of a machined-surface implant placed by osteotomy at the maxillary first molar region.The implant was replaced by a sandblasted, large grit, acid-etched SLA surface with a six-year survival rate follow-up.Clinical and radiographic assessments were performed every six months. Results: Data revealed implant osseointegrationstability as well as tissue biocompatibility and prosthetic functionality. Conclusion: The literature on technicallyadvanced implant surfaces suggests that the posterior maxilla is a safe and predictable site for fixed implant-supportedrehabilitation.

Cyto-, myelo- and chemoarchitecture of the prefrontal cortex of the Cebus monkey.

BACKGROUND: According to several lines of evidence, the great expansion observed in the primate prefrontal cortex (PfC) was accompanied by the emergence of new cortical areas during phylogenetic development. As a consequence, the structural heterogeneity noted in this region of the primate frontal lobe has been associated with diverse behavioral and cognitive functions described in human and non-human primates. A substantial part of this evidence was obtained using Old World monkeys as experimental model; while the PfC of New World monkeys has been poorly studied. In this study, the architecture of the PfC in five capuchin monkeys (Cebus apella) was analyzed based on four different architectonic tools, Nissl and myelin staining, histochemistry using the lectin Wisteria floribunda agglutinin and immunohistochemistry using SMI-32 antibody. RESULTS: Twenty-two architectonic areas in the Cebus PfC were distinguished: areas 8v, 8d, 9d, 12l, 45, 46v, 46d, 46vr and 46dr in the lateral PfC; areas 11l, 11m, 12o, 13l, 13m, 13i, 14r and 14c in the orbitofrontal cortex, with areas 14r and 14c occupying the ventromedial corner; areas 32r, 32c, 25 and 9m in the medial PfC, and area 10 in the frontal pole. This number is significantly higher than the four cytoarchitectonic areas previously recognized in the same species. However, the number and distribution of these areas in Cebus were to a large extent similar to those described in Old World monkeys PfC in more recent studies. CONCLUSIONS: The present parcellation of the Cebus PfC considerably modifies the scheme initially proposed for this species but is in line with previous studies on Old World monkeys. Thus, it was observed that the remarkable anatomical similarity between the brains of genera Macaca and Cebus may extend to architectonic aspects. Since monkeys of both genera evolved independently over a long period of time facing different environmental pressures, the similarities in the architectonic maps of PfC in both genera are issues of interest. However, additional data about the connectivity and function of the Cebus PfC are necessary to evaluate the possibility of potential homologies or parallelisms.

Sodium hyaluronate accelerates the healing process in tooth sockets of rats.

OBJECTIVE: In this study we evaluated the effects of sodium hyaluronate (HY) in the healing process of tooth sockets of rats. DESIGN: Immediately after the extraction of the upper first molars of male Holtzman rats, right sockets were treated with 1% HY gel (approximately 0.1 ml), while left sockets were used as control (blood clot). The animals were sacrificed at 2, 7, and 21 days after tooth extraction and upper maxillaries processed for histological and morphometric analysis of the apical and medium thirds of the sockets. Carbopol, an inert gel, was used to evaluate the mechanical effect of gel injection into sockets. Expression of bone morphogenetic protein-2 (BMP-2) and osteopontin (OPN) was determined by immunohistochemistry at 1, 2, 3, 4, 5, and 7 days after tooth extraction. RESULTS: Histological analysis showed that HY treatment induced earlier trabecular bone deposition resulting in a bone matrix more organized at 7 and 21 days after tooth extraction. Also, HY elicited significant increase in the amount of bone trabeculaes at 7 and 21 days after tooth extraction (percentage of trabecular bone area at 7 days: 13.21+/-4.66% vs. 2.58+/-1.36% in the apical third of control sockets) and in the vessels counting at 7 days. Conversely, the number of cell nuclei was decreased in HY-treated sockets. Additionally, expression of BMP-2 and OPN was enhanced in HY-treated sockets compared with control sockets. CONCLUSIONS: These findings suggest that HY accelerates the healing process in tooth sockets of rats stimulating the expression of osteogenic proteins.

Querion de Celsus en la vulva: reporte de un caso / Kerion celsi in vulva: case report

El Querion de Celsus es una patología micótica, inflamatoria y supurativa localizada habitualmente en la nuca, cuero cabelludo o en la barba pero que también puede aparecer en áreas de piel lampiña. Presentamos el caso de una paciente femenina de 25 años de edad, quien al ingresar al Hospital Universitario Ruíz y Páez de Ciudad Bolívar, presentaba múltiples lesiones pustulares, pruriginosas y dolorosas a nivel genital, lográndose aislar en ellas el dermatofito Trichophyton rubrum. La paciente recibió tratamiento a base de itraconazol y prednisona, presentando en poco tiempo mejoría evidente de su clínica de ingreso. Por tanto concluimos que se trataba de una presentación atípica del Querion de Celsus.

Ensayo y comunicación en psiquiatría / Essay and communication in psychiatry

Se exponen algunas consideraciones sobre el esquema que se maneja en los medios especializados para la comunicación del conocimiento resultado del proceso de investigación: el así llamado "estilo Vancouver". Se propone el uso de una alternativa que complemente este formato. Se sustenta como alternativa válida al ensayo, género fundamental dentro del mundo científico y humaníatico. Se define al ensayo, se presentan sus principales características. Se estudia con detalle al ensayo científico y se defiende su importancia en la Medicina y la Psiquiatría. Se demuestra como grandes figuras del quehacer psiquiátrico se valieron del ensayo para expresar sus ideas. Se enfatiza en la relación entre ensayo y Psiquiatría en Venezuela, señalando a los psiquiatras de nuestro país que han destacado en el género y la importancia de su obra

Aneurisma disecante de la aorta: estudio anatomopatologico de treinta casos / Dissecting aneurysm of the aorta: an anatomopathological study of 36 cases

Se efectuó el estudio Anatomo-Patológico de una serie de 30 casos de aneurisma disecante de la aorta, autopsiados en el Instituto de Anatomía Patológica, provenientes del Hospital Universitario de Caracas. Se establecieron algunas comparaciones con otras casuísticas respecto a la frecuencia, edad, sexo, antecedentes, asociaciones patológicas y complicaciones. Se revisó la literatura sobre el tema y terminología actual, clasificación y etiopatogenia