Establishment of a multisite umbrella cohort study protocol to describe the epidemiology and aetiologies of acute undifferentiated febrile illness in Latin America.

INTRODUCTION: Acute undifferentiated febrile illnesses (AUFIs) impose a large burden in the tropics. Understanding of AUFI's epidemiology is limited. Insufficient diagnostic capacity hinders the detection of outbreaks. The lack of interconnection in healthcare systems hinders timely response. We describe a protocol to study the epidemiology and aetiologies of AUFI and pathogen discovery in strategic areas of Latin America (LA). METHODS AND ANALYSIS: Global Infectious Diseases Network investigators comprising institutions in Colombia, Dominican Republic, México, Perú and the USA, developed a common cohort study protocol. The primary objective is to determine the aetiologies of AUFI at healthcare facilities in high-risk areas. Data collection and laboratory testing for viral, bacterial and parasitic agents are performed in rural and urban healthcare facilities and partner laboratories. Centralised laboratory and data management cores deploy diagnostic tests and data management tools. Subjects >6 years with fever for <8 days without localised infection are included in the cohort. They are evaluated during the acute and convalescent phases of illness. Study personnel collect clinical and epidemiological information. Blood, urine, nasal or pharyngeal swabs and saliva are collected in the acute phase and blood in convalescent phase. Specimens are banked at -80°C. Malaria, dengue and COVID-19 are tested onsite in the acute phase. The acute-phase serum is PCR tested for dengue, chikungunya, Venezuelan equine encephalitis, Mayaro, Oropouche, Zika, and yellow fever viruses. Paired convalescent and acute serum antibody titters are tested for arbovirus, Leptospira spp, and Rickettsia spp. Serum is used for viral cultures and next-generation sequencing for pathogen discovery. Analysis includes variable distributions, risk factors and regression models. Laboratory results are shared with health authorities and network members. ETHICS AND DISSEMINATION: The protocol was approved by local ethics committees and health authorities. The results will be published in peer-reviewed journals. All study results are shared with local and regional health authorities.

Psychometric Properties of the Family Adaptability and Cohesion Evaluation Scale III in Latin American University Dental Students.

OBJECTIVE: The Family Adaptability and Cohesion Evaluation Scale III (FACES III) is a self-report instrument that enables the assessment of the dimensions of adaptability and cohesion within a family, establishing whether or not that family is functional and classifying it according to categories within those dimensions. The objective of this research was to determine the psychometric properties of this instrument using a sample of dental students from 5 Latin American countries. MATERIALS AND METHODS: The FACES III was administered to a sample of 2888 university dental students from Colombia (35.3%), Chile (34.6%), the Dominican Republic (19%), Argentina (6%), and El Salvador (5.1%). Confirmatory factor analysis was used to examine the factorial structure of the scale, comparing 3 models proposed in the Latin American literature, establishing a multigroup analysis to examine invariance among countries. RESULTS: The results revealed a structure composed of 2 dimensions: cohesion and adaptability. These dimensions showed adequate structure and internal consistency. The invariance of the measurement model in the participating countries was confirmed. CONCLUSION: In general, this study offers evidence of the adequacy of the psychometric properties of FACES III in Colombian, Chilean, Dominican, Argentine, and Salvadoran dental students.

E-learning module for cytopathology education based on virtual microscopy.

INTRODUCTION: In cytopathology education, Virtual Microscopy e-learning modules (VM-eLM) have achieved remarkable results in the improvement and personalization of learning. However, it remains to be determined whether these modules can significantly contribute to improving the accuracy of cytological diagnosis. The aim of this work was to create a VM-eLM for gynecologic cytopathology education designed to improve screening and interpretation skills in two groups of cytologists: experienced and nonexperienced. MATERIALS AND METHODS: The module was designed in Moodle with both Whole Slide Images and Static Images taken from Papanicolaou smears that were diagnosed as: negative for intraepithelial lesion, low-grade squamous intraepithelial lesion, high-grade squamous intraepithelial lesion, squamous cell carcinoma, or adenocarcinoma. We assessed the effectiveness of the module using 1) clinical quality indicators to measure skill development and 2) a user survey. RESULTS: After training, participants significantly improved their cytological screening skills, decreasing their false negative diagnosis by 78% in the non-experienced group and eliminating them entirely in the experienced group. Nonexperienced participants also significantly increased their recognition of low-grade squamous intraepithelial lesion and high-grade squamous intraepithelial lesion by 31% and 50%, respectively. Participants positively evaluated the module, highlighting its novelty, the possibility to train remotely, the immediate feedback and the quality of the Whole Slide Images. CONCLUSIONS: We designed, implemented and tested a VM-eLM for Gynecologic Cytopathology Education that improved cytological screening skills for both non-experienced and experienced cytologists, also increasing the diagnostic accuracy of preinvasive lesions by less experienced cytologists. The module was positively evaluated by participants, who perceived an improvement in their interpretive skills.

Empathy levels among dental students and professors from a dental school in the Dominican Republic / Empatía en estudiantes y profesores de una escuela de odontología de República Dominicana

Abstract Introduction: The concept of empathy has been incorporated as one of the key elements for the achievement of the teaching-learning process goals in health science students. Objective: To estimate and compare the levels of empathy among dental students and professors in the undergraduate dental medicine program at the Universidad Central del Este (Dominican Republic). Materials and methods: Cross-sectional study. The study population (n=264) was divided into two groups: the first consisted of students in their first to fifth year of dental school (N=223; n=215), distributed in two areas (basic-preclinical and clinical courses), while the second group comprised professors working in both areas in the dental school of the university (N=53; n=49). The Jefferson Scale of Empathy (S-Version) was used. The descriptive analysis of the data included the estimation of means, standard deviations and percentages, and the reliability of the data was estimated using Cronbach's alpha. In addition, a two-way ANOVA was performed, calculating the effect size and the statistical power of the test; furthermore, when the Fisher's exact test was significant for any factor, Tukey's test was used to estimate differences between means. A significance level of α<0.05 and β<0.20 was established. Results: Overall empathy scores and compassionate care dimension scores among the professor group did not differ significantly from the scores obtained by the students (basic-preclinical and clinical area), but there were differences between students from both areas (p<0.05). There were no significant differences between the three subgroups in the Perspective Taking and Walking in the Patient's Shoes dimensions (p=0.428 and p=0.866). Conclusion: The levels of empathy and compassionate care dimension of professors are similar to those of students in general (regardless of the area).

Resumen Introducción. El concepto de empatía se ha integrado como uno de los elementos centrales para el logro final del proceso de enseñanza-aprendizaje en estudiantes de ciencias de la salud. Objetivo. Estimar y comparar los niveles de empatía entre estudiantes y profesores de pregrado de odontología de la Universidad Central del Este (República Dominicana). Materiales y métodos. Estudio transversal. La población de estudio (n=264) se dividió en dos grupos: el primero, compuesto por estudiantes de primero a quinto año de la carrera de odontología (N=223; n=215) distribuidos en dos áreas (básica-preclínica y clínica), y el segundo, por los docentes de ambas áreas en la escuela de odontología de la universidad (N=53; n=49). Se utilizó la Escala de Empatía Médica de Jefferson (Versión-S). El análisis descriptivo de los datos incluyó la estimación de medias, desviaciones estándar y porcentajes, y la confiabilidad de los datos se estimó mediante CC de Cronbach; además, se realizó un ANOVA bifactorial, calculándose el tamaño del efecto y la potencia de la prueba, y en los casos en que la prueba exacta de Fisher fue significativa para algún factor, se utilizó la prueba de Tukey para estimar las diferencias entre las medias. El nivel de significancia estadística utilizado fue α<0.05 y β<0.20. Resultados. Los valores globales de empatía y de la dimensión Cuidado con compasión en los profesores no difirieron significativamente con los obtenidos por los estudiantes (área básica-preclínica y clínica), pero sí hubo diferencias entre los estudiantes de ambas áreas (p<0.05). En las dimensiones Adopción de perspectiva y Ponerse en los zapatos del otro no existieron diferencias entre los tres subgrupos (p=0.428 y p=0.866). Conclusión. Los niveles de empatía y de la dimensión Cuidado compasivo de los profesores no difieren de los de los estudiantes en general (ambas áreas).

Psychometry and Cut-off Points of the Jefferson Scale of Empathy in Medical Students in Central America and the Caribbean.

OBJECTIVE: The objective of this study was to determine cut-off points that can be used to differentiate measures of empathy, which would then be classified as high, medium, or low. To do so, we used data from students from 7 medical schools in Colombia, El Salvador, and the Dominican Republic, after determining the psychometric properties of the 3-dimensional model of empathy in the Jefferson Scale of Empathy, S-version (for medical students). MATERIALS AND METHODS: This non-experimental descriptive study had a sample that consisted of 6291 students. The structure and factor invariance were analyzed by country and sex. A hierarchical cluster analysis and a bifactorial analysis of variance were applied. RESULTS: The measure of empathy was reliable on the global scale (α = .82; ω = .88). A confirmatory factor analysis showed that the original model was replicable and adjusted to the data (comparative fit index [CFI] = .90; goodness of fit index = .94), while the multigroup analysis allowed to assume an invariant factor structure by country and gender (ΔCFI < .01). Tables were constructed with cut off points for empathy and its dimensions. DISCUSSION AND CONCLUSION: Our study solves the problem of comparing the scores and the levels of empathy observed in the medical students at different schools of medicine, making said comparisons within and between countries and between genders. The instrument used has adequate psychometric properties and the cut-off values obtained allow the classifying of people with lower or higher levels of empathy.

Decline in empathy levels and sex differences in medical students from the Caribbean / Declinación empática y diferencias según el sexo en estudiantes de medicina del Caribe

Abstract Introduction: Empathy is an important trait in the training of medical students, as it has been shown that it improves the doctor-patient relationship. Objective: To evaluate the decline of empathy levels and possible sex differences in undergraduate medical students from the Universidad Central del Este, Dominican Republic. Materials and methods: Exploratory cross-sectional study. A Spanish version of the Jefferson Scale of Empathy for Medical Students (S-version) Scale was administered in September 2018 to 1 144 1st-year to 5th-year medical students (887 women and 257 men). Data reliability was verified using the Cronbach's alpha and the intraclass correlation coefficient (ICC). A generalized linear equation model (Type III) was applied to analyze data and the Wald chi-squared test was used to determine differences in overall empathy levels and the mean scores obtained in each of its three components based on the year of medical training and sex. Results: Cronbach's alpha was satisfactory (0.839), and the ICC was 0.834 (F=5.68; p=0.005). The variability of the estimated curves in relation to empathic behavior by course (year of medical training) and sex was observed using linear and non-linear regression equations: Wald x2=115.6, p=0.0001 between courses; and Wald x2 =12.85, p=0.001 between men and women. Conclusions: Sex differences were observed regarding empathy levels in the study population. Moreover, a decline in empathy levels (overall empathy and Compassionate Care component in men and Walking in the Patient's Shoes component in men and women) was also observed as students progressed in their medical training. The behavior of these data raises questions regarding the need to determine the factors causing these differences and the decline in empathy levels.

Resumen Introducción. La empatia es un rasgo importante en los estudiantes de medicina, ya que se ha demostrado que mejora la relación médico-paciente. Objetivo. Evaluar la declinación empática y las posibles diferencias según el sexo en los niveles de empatia en estudiantes de pregrado de Medicina en la Universidad Central del Este, República Dominicana. Materiales y métodos. Estudio exploratorio transversal. La versión en español de la Escala de Empatia de Jefferson adaptada para estudiantes de medicina (versión S) fue aplicada a 1 144 estudiantes de medicina de 1° a 5° año (887 mujeres y 257 hombres). La confiabilidad de los datos se verificó mediante el alfa de Cronbach y el coeficiente de correlación intraclase (CCI). Los datos se analizaron utilizando un modelo de ecuación lineal generalizada (Tipo III) y se utilizó la prueba x2 de Wald para determinar las diferencias en los niveles globales de empatia y los puntajes promedio de sus tres componentes según el año de formación y el sexo. Resultados. El alfa de Cronbach fue satisfactorio (0.839) y el CCI fue de 0.834 (F=5.68; p=0.005). Mediante ecuaciones de regresión lineal y no lineal se observó variabilidad de las curvas estimadas en relación con el comportamiento empático según el curso (año de formación médica) y el sexo: entre cursos: x2 de Wald= 115.6; p=0.000i, y entre hombres y mujeres: x2 de Wald= 12.85; p=0.001). Conclusiones. Se observaron diferencias en los niveles de empatia según el sexo; también se evidenció una declinación en los niveles de empatia (empatia global y componente Cuidado con compasión en los hombres, y en el componente Ponerse en los zapatos del otro en hombres y mujeres) a medida que los estudiantes avanzaban en su formación. El comportamiento de estos datos genera interrogantes relacionados con la necesidad de determinar los factores que causan estas diferencias y dicha declinación empática.

Physicochemical and biological characterization of nanovenoms, a new tool formed by silica nanoparticles and Crotalus durissus terrificus venom.

Nanoparticles (NPs) are being studied due to their potential use as therapeutic and immunomodulatory tools, including their ability to transport antigens with the aim to induce a specific immune response. The production of snake antivenoms (AV) involves several inoculations of venom (V) in the presence of adjuvants (ADJ) to improve the immune response of inoculated animals, causing a decrease in its quality and shelf life. Therefore, it is interesting to develop new strategies for reduce these side effects. For that reason, associating V to NPs to replace conventional ADJ could be a useful tool for future AV production. In this work, nanovenoms (NVs) were generated by the adsorption of Crotalus durissus terrificus (Cdt) V proteins over silica NPs (SiNPs) synthesized according to the Stöber method. Microphotographies obtained under Transmission Electron Microscopy (TEM) displayed a protein crown over NPs and Fourier Transform Infrared (FT-IR) presented the expected spectra for NVs resulting from the sum of those exhibited by Cdt V and SiNPs separately. SDS PAGE and immunoblotting assays confirmed the presence of proteins over SiNPs. Furthermore, the different enzymatic activities detected demonstrated that SiNPs were capable of binding V proteins preserving its activity and therefore would keep its native structure. In the same way, the NVs conserve the potential cytotoxic effects present in the V as we observed when culturing THP-1 cells with these complexes. This evidence allows us to infer that developed NVs could be used as a new platform for the production of antisera or for immunomodulatory therapies.

Directional asymmetry in the volume of the human habenula.

Brain asymmetry is a conserved feature in vertebrates. The dorsal diencephalic habenular complex shows conspicuous structural and functional asymmetries in a wide range of species, yet it is unclear if this condition is also present in humans. Addressing this possibility becomes relevant in light of recent findings presenting the habenula as a novel target for therapeutic intervention of affective disorders through deep brain stimulation. Here we performed volumetric analyses in postmortem diencephalic samples of male and female individuals, and report for the first time, the presence of directional asymmetries in the volume of the human habenula. The habenular volume is larger on the left side in both genders, a feature that can be explained by an enlargement of the left lateral habenula compared to the right counterpart. In contrast, the volume of the medial habenula shows no left-right directional bias in either gender. It is remarkable that asymmetries involve the lateral habenula, which in humans is particularly enlarged compared to other vertebrates and plays relevant roles in aversive processing and aversively motivated learning. Our findings of structural asymmetries in the human habenula are consistent with recent observations of lateral bias in activation, metabolism and damage of the human habenula, highlighting a potential role of habenular laterality in contexts of health and illness.

Presence of Telocytes in a Non-innervated Organ: The Placenta.

This chapter discusses the relationship between failure in placentation and the subsequent alterations in the normal structure of the placenta. Interstitial Cajal-like cells (ICLC) were observed for the first time in the human placenta in 2007 and later were named telocytes. Strong evidence confirms that in the placental chorionic villi, TC are located strategically between the smooth muscle cells (SMC) of the fetal blood vessel wall and the stromal myofibroblasts. As the placenta is a non-innervated organ and considering the strategic position of telocytes in chorionic villi, it has been postulated that their function would be related to signal transduction mechanisms involved in the regulation of the blood flow in the fetal vessels, as well as in the shortening/lengthening of the chorionic villi providing the necessary rhythmicity to the process of maternal/fetal metabolic exchange. In this context, telocytes represent part of a functional triad: "SMC of fetal blood vessel-telocyte-myofibroblast." This triad takes part in the regulation of fetal growth and development via transport of nutrients and gases. This chapter also discusses the alterations in the metabolic maternal-fetal exchange, leading to intrauterine growth retardation and preeclampsia. Additionally, the apoptosis undergoing in the preeclamptic hypoxic placenta affects all the chorionic villi cells, including telocytes and myofibroblast, and not only trophoblast, as it has been so far considered. In consequence, we proposed that apoptosis affects the triad structure and alters the placental function, subsequently affecting the normal fetal growth and development.

Placental Hypoxia Developed During Preeclampsia Induces Telocytes Apoptosis in Chorionic Villi Affecting The Maternal-Fetus Metabolic Exchange.

Telocytes (TC) are a new type of stromal cells initially found and studied in digestive and extra- digestive organs. These cells have a small cell body with 2 to 5 thin and extremely long cytoplasmic prolongations named telopodes. In recent years, TC have also been described in placental chorionic villi, located in a strategical position between the smooth muscle cells from fetal vessels and the myofibroblasts in the stromal villi. Unlike other organs, the placenta is not innervated and considering the strategic location of TC is has been postulated that TC function would be related to signal transduction mechanisms involved in the regulation of the fetal vessels blood flow, as well as in the shortening/lengthening of the chorionic villi, providing the necessary rhythmicity to the process of maternal/fetal metabolic exchange. Preeclampsia (PE) is a systemic syndrome that affects 4%-6% of pregnancies worldwide. It is characterized by a placental state of ischemia-hypoxia which triggers an oxidative stress stage with the concomitant production of reactive oxygen species (ROS) leading to an increase in the degree of placental apoptosis. Placental vascular tone is regulated by the vasodilator nitric oxide (NO) and, in PE cases, NO is diverted towards the formation of peroxynitrite, a powerful oxidative agent whose activity leads to an increase of placental apoptosis degree that compromises TC and myofibroblasts, a key feature we would like to emphasize in this work.

Ganglionar nervous cells and telocytes in the pancreas of Octodon degus: extra and intrapancreatic ganglionar cells and telocytes in the degus.

This study shows for the first time the presence of intra and extrapancreatic ganglionar neurons and telocytes in Octodon degus such as those described in human and guinea pig pancreas. Pancreatic ganglionar neurons were identified by their histological characteristics as well as their positive immunostaining with mouse anti-human neuron specific enolase (NSE) antibody. Somatostatin secreting delta cells (D cells) in the islets of Langerhans were identified by positive immunostaining with rabbit antihuman polyclonal somatostatin antibody. Electron microscopy evidenced the presence of some unmyelinated axons in the interlobular spaces or septa, usually located adjacent to blood vessels and the exocrine epithelial ducts. The presence of telocytes with at least 2 telopodes was observed in the interlobular space, frequently in close spatial relationship with blood vessels and nerve endings. Telocytes were often observed in the vicinity or even in close proximity with both secretory acini and exocrine epithelial ducts and regulatory nerves and blood vessel apparatuses. A possible framework has been put forward within which such structures might contribute to elicit physiological responses in the pancreas. Further studies of synaptic interactions within and between pancreatic neuron cells are needed to help clarify the morphological results reported here. A broad overview of the field of neurogastroenterology with focus on the pancreas of O. degus related to the enteric nervous system (ENS) is provided in order to help design future studies on the connections of specific neurons forming pancreatic pathways, their neurotransmission processes and how disruption of these pathways may contribute to pancreatic disease.

Placental hypoxia and foetal development versus alcohol exposure in pregnancy.

AIMS: To examine the causes of variability in the effect of maternal drinking on the foetus, with particular reference to the pattern, frequency and duration of the period of drinking, differences in maternal, foetal and placental metabolism of ethanol/acetaldehyde, and genetic factors. METHODS: Narrative review of published studies of the pathogenesis of foetal alcohol syndrome (FAS) with emphasis in the development of the central nervous system. RESULTS: Animal models suggest that acetaldehyde, the primary hepatic oxidative metabolite of ethanol, reaches the foetus either by placental production or by placental transference, which in turn could affect foetal growth and development. The most likely hypothesis regarding the decrease of foetal growth is via hypoxia and increased oxidative/nitrative stress, which interfere with cellular processes that require oxygen in order to function adequately, such as placental transport. CONCLUSION: There seems to be an association between the teratogenic effect, hypoxia and oxidative stress, the molecular mechanism involved (e.g. apoptosis) and the range of effects. The review sums ups the evidence that could explain some of the abnormalities in the brain development that could be related to behavioural problems observed in individuals with FAS/foetal alcohol spectrum disorder. This suggests that alcohol consumption produces failures in the normal migration of radial cells, from which the rest of the brain cells would eventually develop.

Morphologic and immunohistochemical organization of the human habenular complex.

The habenular complex (HbCpx) is a phylogenetically conserved brain structure located in the epithalamus of vertebrates. Despite its fundamental role in decision-making processes and the proposed link between habenular dysfunction and neuropsychiatric conditions, little is known about the structural and functional organization of the HbCpx in humans. The goal of this study was thus to provide a first systematic morphologic and immunohistochemical analysis of the human HbCpx to begin dissecting its nuclear and subnuclear organization. Our results confirmed that the human HbCpx is subdivided into medial (MHb) and lateral (LHb) nuclei, each showing a large degree of intranuclear morphologic heterogeneity. Analysis of serially stained sections using a combination of morphologic and immunohistochemical criteria allowed the distinction of five subnuclei in both the MHb and LHb. Overall, the observed subnuclear organization of the MHb in humans resembles the organization of subnuclei in the MHb of rats. The shape, relative size, and intranuclear organization of the LHb, however, show significant differences. The contribution of the LHb to the entire HbCpx is about five times larger in humans than in rats. Noteworthy, a dorsal domain of the LHb that contains afferent myelinated fibers from the stria medullaris and shows GABA-(B) -R(1) immunoreactive cells, appears substantially enlarged in humans when compared to rats. This feature seems to account for a large part of the relative growth in size of the LHb in humans and opens the intriguing possibility of an increased influence of limbic and striatal afferents into the LHb of humans.

Early alterations in the electrophysiological properties of rat spinal motoneurones following neonatal axotomy.

Early in development, motoneurones are critically dependent on their target muscles for survival and differentiation. Previous studies have shown that neonatal axotomy causes massive motoneurone death and abnormal function in the surviving motoneurones. We have investigated the electrophysiological and morphological properties of motoneurones innervating the flexor tibialis anterior (TA) muscle during the first week after a neonatal axotomy, at a time when the motoneurones would be either in the process of degeneration or attempting to reinnervate their target muscles. We found that a large number ( approximately 75%) of TA motoneurones died within 3 weeks after neonatal axotomy. Intracellular recordings revealed a marked increase in motoneurone excitability, as indicated by changes in passive and active membrane electrical properties. These changes were associated with a shift in the motoneurone firing pattern from a predominantly phasic pattern to a tonic pattern. Morphologically, the dendritic tree of the physiologically characterized axotomized cells was significantly reduced compared with age-matched normal motoneurones. These data demonstrate that motoneurone electrical properties are profoundly altered shortly after neonatal axotomy. In a subpopulation of the axotomized cells, abnormally high motoneurone excitability (input resistance significantly higher compared with control cells) was associated with a severe truncation of the dendritic arbor, suggesting that this excitability may represent an early electrophysiological correlate of motoneurone degeneration.

Inhibidor adquirido del factor VIII en paciente no hemofílico. Caso clínico - actualización / Acquired factor VIII inhibitors in a non-hemophilic patient. Case report

Se presenta el caso clínico de una paciente joven que instala un síndrome hemorragíparo secundario a un déficit adquirido de la coagulación provocado por la aparición deanticuerpos antifactor VIII. El interés de la presente comunicación radica en que si bien la aparición de inhibidores de la coagulación en pacientes no hemofílicos es un fenómeno raro, se trata de un cuadro grave que puede determinar la muerte del paciente, por lo que es de capital importancia realizar un diagnóstico y tratamiento precoz, así como definir si constituye un trastorno primario o, por el contrario, responde a la existencia de una enfermedad subyacente que el clínico debe diagnosticar. Se realiza una descripción fisiopatológica a fin de facilitar la comprensión de los pasos que permiten arribar al diagnóstico así como una actualización de las herramientas terapéuticas disponibles.

Simultaneous single unit recording in the mitral cell layer of the rat olfactory bulb under nasal and tracheal breathing.

Odor perception depends on the odorant-evoked changes on Mitral/Tufted cell firing pattern within the olfactory bulb (OB). The OB exhibits a significant "ongoing" or spontaneous activity in the absence of sensory stimulation. We characterized this ongoing activity by simultaneously recording several single neurons in the mitral cell layer (MCL) of anesthetized rats and determined the extent of synchrony and oscillations under nasal and tracheal breathing. We recorded 115 neurons and found no significant differences in the mean firing rates between both breathing conditions. Surprisingly, nearly all single units exhibited a long refractory period averaging 14.4 ms during nasal respiration that was not different under tracheal breathing. We found a small incidence (2% of neurons) of gamma band oscillations and a low incidence (8.1%) of correlated firing between adjacent MCL cells. During nasal respiration, a significant oscillation at the respiratory rate was observed in 12% of cells that disappeared during tracheal breathing. Thus, in the absence of odorants, MCL cells exhibit a long refractory period, probably reflecting the intrinsic OB network properties. Furthermore, in the absence of sensory stimulation, MCL cell discharge does not oscillate in the gamma band and the respiratory cycle can modulate the firing of these cells.

Simultaneous Single Unit Recording in the Mitral Cell Layer of the Rat Olfactory Bulb under Nasal and Tracheal Breathing

Odor perception depends on the odorant-evoked changes on Mitral/Tufted cell firing pattern within the olfactory bulb (OB). The OB exhibits a significant "ongoing" or spontaneous activity in the absence of sensory stimulation. We characterized this ongoing activity by simultaneously recording several single neurons in the mitral cell layer (MCL) of anesthetized rats and determined the extent of synchrony and oscillations under nasal and tracheal breathing. We recorded 115 neurons and found no significant differences in the mean firing rates between both breathing conditions. Surprisingly, nearly all single units exhibited a long refractory period averaging 14.4 ms during nasal respiration that was not different under tracheal breathing. We found a small incidence (2% of neurons) of gamma band oscillations and a low incidence (8.1%) of correlated firing between adjacent MCL cells. During nasal respiration, a significant oscillation at the respiratory rate was observed in 12% of cells that disappeared during tracheal breathing. Thus, in the absence of odorants, MCL cells exhibit a long refractory period, probably reflecting the intrinsic OB network properties. Furthermore, in the absence of sensory stimulation, MCL cell discharge does not oscillate in the gamma band and the respiratory cycle can modulate the firing of these cells.

Effects of steroidal and non steroidal drugs on the neovascularization response induced by tumoral TA3 supernatant on CAM from chick embryo.

Angiogenesis, the development of new blood vessels from the existing vascular network, may result as a consequence of the increase or decrease of proangiogenic or antiangiogenic factors, respectively. The tumor itself could up-regulate the production of angiogenic factors. Recently, we established that the steroidal drug betamethasone in low concentration inhibit the neovascularization promoted by TA3 Ts on CAM of chick embryos. We describe here the effects of the non-steroidal drug ketoprofen, alone or in association with betamethasone, on the angiogenesis promoted by TA3 Ts on CAM. The main finding reported here is that the formation of new blood vessels is strongly inhibited by low concentrations of ketoprofen. The association of both drugs produced a synergistic effect, significantly decreasing tumoral supernatant angiogenesis. It is known that steroidal anti-inflammatory drugs inhibit the enzymes required for the production of prostaglandins through a nuclear GR mediated mechanism. This may operate as a general mechanism in endothelial cells as well. Considering that the induction of COX 1 and COX2 are inhibited by ketoprofen, and that these enzymes are located in the stromal compartment of the CAM, we propose that its antiangiogenic effect may occur via inhibition of the two COX isoforms. In fact, we found that ketoprofen induced apoptosis in both the stromal fibroblast and endothelial cells. The potentiated effect of the combination of betamethasone and ketoprofen may have some therapeutic projections in the control of pathological angiogenesis.

Effects of steroidal and non steroidal drugs on the neovascularization response induced by tumoral TA3 supernatant on CAM from chick embryo

Angiogenesis, the development of new blood vessels from the existing vascular network, may result as a consequence of the increase or decrease of proangiogenic or antiangiogenic factors, respectively. The tumor itself could up-regulate the production of angiogenic factors. Recently, we established that the steroidal drug betamethasone in low concentration inhibit the neovascularization promoted by TA3 Ts on CAM of chick embryos. We describe here the effects of the non-steroidal drug ketoprofen, alone or in association with betamethasone, on the angiogenesis promoted by TA3 Ts on CAM. The main finding reported here is that the formation of new blood vessels is strongly inhibited by low concentrations of ketoprofen. The association of both drugs produced a synergistic effect, significantly decreasing tumoral supernatant angiogenesis. It is known that steroidal anti-inflammatory drugs inhibit the enzymes required for the production of prostaglandins through a nuclear GR mediated mechanism. This may operate as a general mechanism in endothelial cells as well. Considering that the induction of COX 1 and COX2 are inhibited by ketoprofen, and that these enzymes are located in the stromal compartment of the CAM, we propose that its antiangiogenic effect may occur via inhibition of the two COX isoforms. In fact, we found that ketoprofen induced apoptosis in both the stromal fibroblast and endothelial cells. The potentiated effect of the combination of betamethasone and ketoprofen may have some therapeutic projections in the control of pathological angiogenesis

Increased electrotonic coupling in spinal motoneurons after transient botulinum neurotoxin paralysis in the neonatal rat.

The effect of early postnatal blockade of neuromuscular transmission using botulinum neurotoxin (BoNT) type A on motoneuron gap junctional coupling was studied by means of intracellular recordings and biocytin labeling using the in vitro hemisected spinal cord preparation of neonatal rats. The somata of tibialis anterior (TA) motoneurons were retrogradely labeled at birth (P0) by intramuscular injection of fluorescent tracers. Two days later, BoNT was injected unilaterally into the TA muscle. The toxin blocked neuromuscular transmission for the period studied (P4-P7) as shown by tension recordings of the TA muscle. Retrograde horseradish peroxidase tracing in animals reared to adulthood demonstrated no significant cell death or changes in the soma size of BoNT-treated TA motoneurons. Intracellular recordings were carried out in prelabeled control and BoNT-treated TA motoneurons from P4 to P7. Graded stimulation of the ventral root at subthreshold intensities elicited short-latency depolarizing (SLD) potentials that consisted of several discrete components reflecting electrotonic coupling between two or more motoneurons. BoNT treatment produced a significant increase (67%) in the maximum amplitude of the SLD and in the number of SLD components as compared with control (3.1 +/- 1.7 vs. 1.4 +/- 0.7; means +/- SD). The morphological correlates of electrotonic coupling were investigated at the light microscope level by studying the transfer of biocytin to other motoneurons and the putative sites of gap junctional interaction. The dye-coupled neurons clustered around the injected cell with close somato-somatic, dendro-somatic and -dendritic appositions that might represent the sites of electrotonic coupling. The size of the motoneuron cluster was, on average, 2.2 times larger after BoNT treatment. Our findings demonstrate that a short-lasting functional disconnection of motoneurons from their target muscle delays motoneuron maturation by halting the elimination of gap junctional coupling that normally occurs during early postnatal development.