Endothelial Cell APOE3 Regulates Neurovascular, Neuronal, and Behavioral Function.

BACKGROUND: Specialized brain endothelial cells and human APOE3 are independently important for neurovascular function, yet whether APOE3 expression by endothelial cells contributes to brain function is currently unknown. In the present study, we determined whether the loss of endothelial cell APOE3 impacts brain vascular and neural function. METHODS: We developed APOE3fl/fl/Cdh5(PAC)-CreERT2+/- (APOE3Cre+/-) and APOE3fl/fl/Cdh5(PAC)-CreERT2-/- (APOE3Cre-/-, control) mice and induced endothelial cell APOE3 knockdown with tamoxifen at ≈4 to 5 weeks of age. Neurovascular and neuronal function were evaluated by biochemistry, immunohistochemistry, behavioral testing, and electrophysiology at 9 months of age. RESULTS: We found that the loss of endothelial APOE3 expression was sufficient to cause neurovascular dysfunction including higher permeability and lower vessel coverage in tandem with deficits in spatial memory and fear memory extinction and a disruption of cortical excitatory/inhibitory balance. CONCLUSIONS: Our data collectively support the novel concept that endothelial APOE3 plays a critical role in the regulation of the neurovasculature, neural circuit function, and behavior.

Prefrontal α7nAChR Signaling Differentially Modulates Afferent Drive and Trace Fear Conditioning Behavior in Adolescent and Adult Rats.

Increased level of kynurenic acid is thought to contribute to the development of cognitive deficits in schizophrenia through an α7nAChR-mediated mechanism in the prefrontal cortex (PFC). However, it remains unclear to what extent disruption of PFC α7nAChR signaling impacts afferent transmission and its modulation of behavior. Using male rats, we found that PFC infusion of methyllycaconitine (MLA; α7nAChR antagonist) shifts ventral hippocampal-induced local field potential (LFP) suppression to LFP facilitation, an effect only observed in adults. Hippocampal stimulation can also elicit a GluN2B-mediated LFP potentiation (when PFC GABAAR is blocked) that is insensitive to MLA. Conversely, PFC infusion of MLA diminished the gain of amygdalar transmission, which is already enabled by postnatal day (P)30. Behaviorally, the impact of prefrontal MLA on trace fear-conditioning and extinction was also age related. While freezing behavior during conditioning was reduced by MLA only in adults, it elicited opposite effects in adolescent and adult rats during extinction as revealed by the level of reduced and increased freezing response, respectively. We next asked whether the late-adolescent onset of α7nAChR modulation of hippocampal inputs contributes to the age-dependent effect of MLA during extinction. Data revealed that the increased freezing behavior elicited by MLA in adult rats could be driven by a dysregulation of the GluN2B transmission in the PFC. Collectively, these results indicate that distinct neural circuits are recruited during the extinction of trace fear memory in adolescents and adults, likely because of the late-adolescent maturation of the ventral hippocampal-PFC functional connectivity and its modulation by α7nAChR signaling.SIGNIFICANCE STATEMENT Abnormal elevation of the astrocyte-derived metabolite kynurenic acid in the prefrontal cortex (PFC) is thought to impair cognitive functions in schizophrenia through an α7nAChR-mediated mechanism. Here, we found that prefrontal α7nAChR signaling is recruited to control the gain of hippocampal and amygdalar afferent transmission in an input-specific, age-related manner during the adolescent transition to adulthood. Behaviorally, prefrontal α7nAChR modulation of trace fear memory was also age-related, likely because of the late-adolescent maturation of the ventral hippocampal pathway and its recruitment of PFC GABAergic transmission enabled by local α7nAChR signaling. Collectively, these results reveal that distinct α7nAChR-sensitive neural circuits contribute to regulate behavior responses in adolescents and adults, particularly those requiring proper integration of hippocampal and amygdalar inputs by the PFC.

Thermal degradation characteristics and gasification kinetics of camel manure using thermogravimetric analysis.

In this work, the sustainable valorisation of camel manure has been studied using thermogravimetric analysis. The gasification tests were performed from ambient conditions to 950 °C at 10, 20, and 50 °C/min under an O2 environment. The TGA data were applied to determine the kinetics of the O2 gasification. Single-heating rate models (Arrhenius and Coats-Redfern) and multi-heating rate models (Distributed activation energy, Friedman, Flynn-Wall-Ozawa, Starink, and Kissinger-Akahira-Sunose) were applied to estimate the kinetics of the process. Between the two single-heating rate models, the Coats-Redfern method fitted best with the experimental data. Among the multi-heating rate models, the Flynn-Wall-Ozawa model fitted best with the experimental results. The kinetic parameters-frequency factor, activation energy, and order of reaction were estimated using the Flynn-Wall-Ozawa model (the best-fitting model) and the estimated kinetic parameters were used to calculate the thermodynamic properties-Gibbs free energy, enthalpy, and entropy. The information on these kinetic and thermodynamic properties can be useful for the design of gasifiers and for optimising the O2 gasification operating conditions.

Non-isothermal drying of bio-wastes: Kinetic analysis and determination of effective moisture diffusivity.

A macro-thermogravimetric analysis (macro-TGA) was applied to analyse the non-isothermal drying of different bio-wastes (quince solid waste, grape marc and pumpkin shell from different enterprises located in San Juan Province, Argentina). The experimental data were obtained at three heating rates (5, 10 and 15 K/min) and two different initial moisture contents (30 and 50% w/w). These data were fitted using the Coats-Redfern and Sharp methods. The D2 model showed the best fitting for all experiments when using the Coats-Redfern method. It is assumed that drying occurs on the solid boundary. The predicted Ea values ranged from 43.60 to 64.50 kJ/mol for the three bio-wastes under the different experimental conditions. The Ea value slightly increases with the increase in heating rate because the wastes require more energy to undergo drying. Deff increases moderately with temperature at the beginning of the dehydration process; then, this increasing behaviour is significant due to the loss of continuous moisture channels. Otherwise, Deff increases with the initial moisture content, showing that the humidity of the samples did not reach the saturation content.

Macro-TGA steam-assisted gasification of lignocellulosic wastes.

The kinetics of the steam-assisted gasification for three different agro-industrial solid wastes (sawdust, olive and plum pits) was studied by macro thermo-gravimetric analysis (macro-TGA) at different heating rates (5, 10 and 15 K/min). The progressive CO release was moreover monitored to fully identify each step of the global gasification process. A single-step kinetics modelling was applied by using the Coats-Redfern method, with both a first order model for pyrolysis and a Ginstling - Brounstein 3D-diffusion model for the gasification stages, respectively. A comparison between macro-TGA and previous TGA results for the same bio-wastes was performed. Results indicated that the reaction proceeds in three well-defined and subsequent stages, involving water evaporation [298-473 K], biomass de-volatilization [473-648 K] with the highest production of CO, and char gasification as final step. Reaction rate parameters of the Arrhenius equation were determined for both the pyrolysis and gasification steps.

Astrocyte Dysfunction in Developmental Neurometabolic Diseases.

Astrocytes play crucial roles in maintaining brain homeostasis and in orchestrating neural development, all through tightly coordinated steps that cooperate to maintain the balance needed for normal development. Here, we review the alterations in astrocyte functions that contribute to a variety of developmental neurometabolic disorders and provide additional data on the predominant role of astrocyte dysfunction in the neurometabolic neurodegenerative disease glutaric acidemia type I. Finally, we describe some of the therapeutical approaches directed to neurometabolic diseases and discuss if astrocytes can be possible therapeutic targets for treating these disorders.

[Soil transmitted helminthiasis in Argentina. A systematic review]. / Geohelmintiasis en la Argentina. Una revisión sistemática.

A systematic review of surveys performed between 1980 and 2011 (published in MEDLINE/Pubmed and/or LILACS indexed journals, available in the baseline data from a Mass Deworming National Program (MDNP, 2005) was used to identify the prevalence, distribution and detection of risk areas for soil transmitted helminth infections (STH) in Argentina. We found 310 publications in the database using the pre-defined key-words (medical subject headings) for research purposes. Only 24 articles with 26 surveillance sites in 8 provinces and a total of 5495 surveyed individuals fulfilled the inclusion criteria. Frequency rates for STH had a wide range: Ascaris lumbricoides: 0-67%, hookworms: 0-90%, Trichuris trichiura: 0-24.6 and Strongyloides stercoralis: 0-83%. The estimated combined incidence varied from 0.8% to 88.6%. Baseline surveys from the MDNP reporting on 1943 children from 12 provinces confirmed the heterogeneity, with combined STH frequency rates ranging from 0 to 42.7%. Surveys included in this review showed that the distribution of STH in Argentina is not homogeneous, with areas of high incidence (> 20%) in the northeastern and northwestern provinces where mass deworming activities would be highly beneficial. In several surveys, the high overall incidence was mostly due to hookworms and S. stercoralis, a situation to be considered when selecting diagnostic and therapeutic control strategies. The scarcity or absence of data from various provinces and the availability of less than 8000 surveyed individuals should be considered.

Late-adolescent onset of prefrontal endocannabinoid control of hippocampal and amygdalar inputs and its impact on trace-fear conditioning behavior.

Prefrontal cortex (PFC) maturation during adolescence is characterized by structural and functional changes, which involve the remodeling of GABA and glutamatergic synapses, as well as changes in the endocannabinoid system. Yet, the way PFC endocannabinoid signaling interacts with local GABA and glutamatergic function to impact its processing of afferent transmission during the adolescent transition to adulthood remains unknown. Here we combined PFC local field potential recordings with local manipulations of 2-AG and anandamide levels to assess how PFC endocannabinoid signaling is recruited to modulate ventral hippocampal and basolateral amygdalar inputs in vivo in adolescent and adult male rats. We found that the PFC endocannabinoid signaling does not fully emerge until late-adolescence/young adulthood. Once present, both 2-AG and anandamide can be recruited in the PFC to limit the impact of hippocampal drive through a CB1R-mediated mechanism whereas basolateral amygdalar inputs are only inhibited by 2-AG. Similarly, the behavioral effects of increasing 2-AG and anandamide in the PFC do not emerge until late-adolescence/young adulthood. Using a trace fear conditioning paradigm, we found that elevating PFC 2-AG levels preferentially reduced freezing behavior during acquisition without affecting its extinction. In contrast, increasing anandamide levels in the PFC selectively disrupted the extinction of trace fear memory without affecting its acquisition. Collectively, these results indicate a protracted recruitment of PFC endocannabinoid signaling, which becomes online in late adolescence/young adulthood as revealed by its impact on hippocampal and amygdalar-evoked local field potential responses and trace fear memory behavior.

Etiologies of Mild and Moderate Diarrheal Illness among Children in Consuelo, Dominican Republic.

Since the rotavirus vaccine was included in the Dominican Republic's national immunization schedule in 2012, the microbiologic etiologies of acute gastroenteritis have not been described. This study aimed to determine the contribution of rotavirus as an etiology of acute gastroenteritis over a 12-month period in children under 5 years of age in both an inpatient and an outpatient setting in Consuelo, Dominican Republic. All children who were seen at Niños Primeros en Salud clinic or admitted to Hospital Municipal Dr. Angel Ponce Pinedo for acute gastroenteritis during January 2021-April 2022 were enrolled in the study. Stools were evaluated for rotavirus, enteric parasites, and pathogenic bacteria. Pathogen detection was compared between outpatients and inpatients and on the basis of child's vaccination status. From 181 children enrolled, 170 stool samples were collected, 28 (16.5%) from inpatients and 142 (83.5%) from outpatients. Rotavirus was the most commonly detected pathogen and was proportionately more common among hospitalized children, with nine (32.1%) cases among hospitalized children and 16 (11.3%) among outpatient children. (Pearson χ2 = 8.1, P = 0.004). Among patients with a positive rotavirus result, vaccination rate was lower among moderate (hospitalized) (three of six; 50%) compared with mild (outpatient) diarrhea patients (12 of 15; 80%). Giardia lamblia (10%) was the next most prevalent pathogen detected in both inpatients and outpatients using standard laboratory measures. Despite the availability of rotavirus vaccination, rotavirus remains a common cause of gastrointestinal illness among children under 5 years of age in our cohort. Incomplete vaccination status was associated with hospitalization for gastrointestinal illness.

Brain atlas of the annual Garcialebias charrua fish.

Annual fish have become attractive study models for a wide range of disciplines, including neurobiology. These fish have developed different survival strategies. As a result, their nervous system is under considerable selective pressure when facing extreme environmental situations. Fish from the Austrolebias group exhibit rapid neurogenesis in different brain regions, possibly as a result of the demanding conditions of a changing habitat. Knowledge of cerebral histology is essential for detecting ontogenic, anatomical, or cytoarchitectonic changes in the brain during the short lifespan of these fish, such as those reflecting functional adaptive plasticity in different systems, including sensory structures. The generation of an atlas of Garcialebias charrua (previously known as Austrolebias charrua) establishes its anatomical basis as a representative of a large group of fish that share similarities in their way of life. In this work, we present a detailed study of both gross anatomy and microscopic anatomy obtained through serial sections stained with the Nissl technique in three orientations: transverse, horizontal, and parasagittal planes. This atlas includes accurate drawings of the entire adult brain of the male fish Garcialebias charrua, showing dorsal, ventral, and lateral views, including where emergence and origin of cranial nerves. This brain atlas allows us to understand histoarchitecture as well as the location of neural structures that change during adult neurogenesis, enabling comparisons within the genus. Simultaneously, this atlas constitutes a valuable tool for comparing the brains of other fish species with different behaviors and neuroecologies.

Effects of early life adversity and adolescent basolateral amygdala activity on corticolimbic connectivity and anxiety behaviors.

Early postnatal development of corticolimbic circuitry is shaped by the environment and is vulnerable to early life challenges. Prior work has shown that early life adversity (ELA) leads to hyperinnervation of glutamatergic basolateral amygdala (BLA) projections to the prefrontal cortex (PFC) in adolescence. While hyperinnervation is associated with later-life anxiety behaviors, the physiological changes underpinning corticolimbic and behavioral impacts of ELA are not understood. We tested whether postsynaptic BLA-driven PFC activity is enhanced in ELA-exposed animals, using the maternal separation (MS) model of ELA. PFC local-field potential following BLA stimulation was facilitated in MS-exposed adolescents. Since ELA increases activity of the early-developing BLA, while the PFC exhibits protracted development, we further examined impacts of glutamatergic BLA activity during early adolescence on later-life PFC innervation and heightened anxiety. In early adolescence, MS-exposed animals exhibited decreased anxiety-like behavior, and acute adolescent BLA inhibition induced behaviors that resembled those of MS animals. To examine long-lasting impacts of adolescent BLA activity on innervation, BLA-originating axonal boutons in the PFC were quantified in late adolescence after early adolescent BLA inhibition. We further tested whether late adolescent BLA-PFC changes were associated with anxious reactivity expressed as heightened acoustic startle responses. MS rearing increased BLA-PFC innervation and threat reactivity in late adolescence, however early adolescent BLA inhibition was insufficient to prevent MS effects, suggesting that earlier BLA activity or post-synaptic receptor rearrangement in the PFC drives altered innervation. Taken together, these findings highlight both pre- and postsynaptic changes in the adolescent BLA-PFC circuit following ELA.

Factors Associated With Initiating Breastfeeding and Continuing it for At Least 4 Months in Consuelo, a Rural Town in the Dominican Republic.

Objective. We assessed the proportion of and factors associated with mothers initiating and continuing breastfeeding (BF) for ≥4 months in a rural town of the Dominican Republic. Methods. A survey was administered to 190 mothers of children cared for at a free clinic in Consuelo. Modified bivariate and multivariable Poisson regressions were utilized in data analysis. Results. BF was initiated in 89.5% of cases and continued ≥4 months in 81.7% of cases. Maternal education beyond secondary school [adjusted RR = 1.13, 95% CI: (1.04-1.24), 0.010], and visiting both public and private antenatal clinics [adjusted RR = 1.25; 95% CI: (1.10-1.37), 0.010] were associated with BF initiation. Public and private antenatal clinic attendance [adjusted RR = 1.01, 95% CI: (0.45-2.23), 0.020], Cesarean section [adjusted RR = 0.81, 95% CI: (0.68-0.98), 0.026], number of biological children [adjusted RR = 0.95, 95% CI: (0.90-1.00), 0.032] and maternal employment [adjusted RR = 0.89, 95% CI: (0.79-0.99), 0.048] were associated with BF continuation. Conclusions. These results provide valuable insights for targeting specific populations in future breastfeeding education interventions.

Morphological evidence of the protective effects of a synthetic chalcone against the striatal myelin damage induced by glutaric acid.

Ultrastructural features of striatal white matter and cells in an in vivo model of glutaric acidemia type I created by intracerebral injection of glutaric acid (GA) were analyzed by transmission electron microscopy and immunohistochemistry. To test if the white matter damage observed in this model could be prevented, we administered the synthetic chemopreventive molecule CH38 ((E)-3-(4-methylthiophenyl)-1-phenyl-2-propen-1-one) to newborn rats, previous to an intracerebroventricular injection of GA. The study was done when striatal myelination was incipient and when it was already established (at 12 and 45 days post-injection [DPI], respectively). Results obtained indicate that that the ultrastructure of astrocytes and neurons did not appear significantly affected by the GA bolus. Instead, in oligodendrocytes, the most prominent GA-dependent injury defects included endoplasmic reticulum (ER) stress and nuclear envelope swelling at 12 DPI. Altered and reduced immunoreactivities against heavy neurofilament (NF), proteolipid protein (PLP), and myelin-associated glycoprotein (MAG) together with axonal bundle fragmentation and decreased myelin were also found at both ages analyzed. CH38 by itself did not affect striatal cells or axonal packages. However, the group of rats that received CH38 before GA did not show evidence neither of ER stress nor nuclear envelope dilation in oligodendrocytes, and axonal bundles appeared less fragmented. In this group, labeling of NF and PLP was similar to the controls. These results suggest that the CH38 molecule is a candidate drug to prevent or decrease the neural damage elicited by a pathological increase of GA in the brain. Optimization of the treatments and identification of the mechanisms underlying CH38 protective effects will open new therapeutic windows to protect myelin, which is a vulnerable target of numerous nervous system diseases.

Near-term pregnant women in the Dominican Republic experience high rates of Group B Streptococcus rectovaginal colonization with virulent strains.

Maternal colonization with Group B Streptococcus (GBS) is an important cause of stillbirth, prematurity, and serious infection and death in infants worldwide. Resource constraints limit prevention strategies in many regions. Maternal GBS vaccines in development could be a more accessible prevention strategy, but data on geographic variations in GBS clones are needed to guide development of a broadly effective vaccine. In the Dominican Republic (DR), limited data suggest that pregnant women experience GBS colonization at rates among the highest globally. We aimed to determine the prevalence of maternal rectovaginal GBS colonization and describe clonal characteristics of colonizing strains in the DR. A cross-sectional study assessed rectovaginal GBS colonization in 350 near-term pregnant women presenting for routine prenatal care at an urban tertiary center in the DR. Rectovaginal samples were tested with chromogenic Strep B Carrot Broth and cultured for confirmatory whole-genome sequencing. In a secondary analysis, participants' demographics and histories were assessed for association with GBS colonization. Rectovaginal GBS colonization occurred in 26.6% of women. Serotypes Ia, Ib, II, III, IV, and V were detected, with no one serotype predominating; serotype III was identified most frequently (21.5%). Virulent and emerging strains were common, including CC17 (15.1%) and ST1010 (17.2%). In this first characterization of maternal GBS serotypes in the DR, we found high rates of rectovaginal colonization including with virulent and emerging GBS strains. The serotypes observed here are all targeted by candidate hexavalent GBS vaccines, suggesting effective protection in the DR.

[Aeromonas spp asociated to acute diarrheic disease in Cuba: case-control study]. / Aeromonas spp asociada a enfermedad diarreica aguda en Cuba: estudios de casos y controles.

The members of the genus Aeromonas are currently considered important gastrointestinal pathogens in different geographical areas. From February 1985 to January 2005 several case-control studies were coordinated by the National Reference Laboratory for Diarrheal Diseases from the Pedro Kouri Institute. The study purpose was to analyze a possible pathogenic role for Aeromonas spp in Cuban children with acute diarrhea. In that period 2,322 children less than 5 years old with acute diarrhea were studied for diarhoeal pathogens and another group of 2,072 non hospitalized children without diarrhea during the similar time from the same geographical areas and matched by ages were recruited. In the group of children with diarrheas (cases), Aeromonas spp. was isolated in 166 (7.15%) and in the control group the microorganism was found in only 35 (1.76%). When Aeromonas isolation rates were compared between both groups, we found that probability to isolate this specie was significantly higher in cases than in controls (OR = 4.48, 95% IC: 3.05-6.60; P < 0.001). The Aeromonas species more frequently isolated were A. caviae, A. hydrophila, and A. veronii bv sobria. Other enteric pathogens detected in children with diarrhea were: Shigella spp in 418 (18%) (P < 0.0001), Salmonella spp in 53 (2.3%) (P < 0.01), and enteropathogenic E. coli in 58 (2.49%) (P < 0.05).

Plasticity of cell proliferation in the retina of Austrolebias charrua fish under light and darkness conditions.

Austrolebias annual fishes exhibit cell proliferation and neurogenesis throughout life. They withstand extreme environmental changes as their habitat dries out, pressuring nervous system to adapt. Their visual system is challenged to adjust as the water becomes turbid. Therefore, this study focused on how change in photic environment can lead to an increased cell proliferation in the retina. We administered 5-chloro-2'- deoxyuridine (CldU) and 5-iodo-2'-deoxyuridine (IdU) at different temporal windows to detect cell proliferation in natural light and permanent darkness. Stem/progenitor cells were recognized as IdU+/CldU + nuclei co-labeled with Sox2, Pax6 or BLBP found in the ciliary marginal zone (CMZ). The expression pattern of BLBP + glial cells and ultrastructural analysis indicates that CMZ has different cell progenitors. In darkness, the number of dividing cells significantly increased, compared to light conditions. Surprisingly, CMZ IdU+/CldU + cell number was similar under light and darkness, suggesting a stable pool of stem/progenitor cells possibly responsible for retinal growth. Therefore, darkness stimulated cell progenitors outside the CMZ, where Müller glia play a crucial role to generate rod precursors and other cell types that might integrate rod-dependent circuits to allow darkness adaptation. Thus, the Austrolebias fish retina shows great plasticity, with cell proliferation rates significantly higher than that of brain visual areas.

Colocalization Analysis of Peripheral Myelin Protein-22 and Lamin-B1 in the Schwann Cell Nuclei of Wt and TrJ Mice.

Myelination of the peripheral nervous system requires Schwann cells (SC) differentiation into the myelinating phenotype. The peripheral myelin protein-22 (PMP22) is an integral membrane glycoprotein, expressed in SC. It was initially described as a growth arrest-specific (gas3) gene product, up-regulated by serum starvation. PMP22 mutations were pathognomonic for human hereditary peripheral neuropathies, including the Charcot-Marie-Tooth disease (CMT). Trembler-J (TrJ) is a heterozygous mouse model carrying the same pmp22 point mutation as a CMT1E variant. Mutations in lamina genes have been related to a type of peripheral (CMT2B1) or central (autosomal dominant leukodystrophy) neuropathy. We explore the presence of PMP22 and Lamin B1 in Wt and TrJ SC nuclei of sciatic nerves and the colocalization of PMP22 concerning the silent heterochromatin (HC: DAPI-dark counterstaining), the transcriptionally active euchromatin (EC), and the nuclear lamina (H3K4m3 and Lamin B1 immunostaining, respectively). The results revealed that the number of TrJ SC nuclei in sciatic nerves was greater, and the SC volumes were smaller than those of Wt. The myelin protein PMP22 and Lamin B1 were detected in Wt and TrJ SC nuclei and predominantly in peripheral nuclear regions. The level of PMP22 was higher, and those of Lamin B1 lower in TrJ than in Wt mice. The level of PMP22 was higher, and those of Lamin B1 lower in TrJ than in Wt mice. PMP22 colocalized more with Lamin B1 and with the transcriptionally competent EC, than the silent HC with differences between Wt and TrJ genotypes. The results are discussed regarding the probable nuclear role of PMP22 and the relationship with TrJ neuropathy.

GABAergic signalling in a neurogenic niche of the turtle spinal cord.

The region that surrounds the central canal (CC) in the turtle spinal cord is a neurogenic niche immersed within already functional circuits, where radial glia expressing brain lipid binding protein (BLBP) behave as progenitors. The behaviour of both progenitors and neuroblasts within adult neurogenic niches must be regulated to maintain the functional stability of the host circuit. In the brain, GABA plays a major role in this kind of regulation but little is known about GABAergic signalling in neurogenic niches of the postnatal spinal cord. Here we explored the action of GABA around the CC of the turtle spinal cord by combining patch-clamp recordings of CC-contacting cells, immunohistochemistry for key components of GABAergic signalling and Ca(2+) imaging. Two potential sources of GABA appeared around the CC: GABAergic terminals and CC-contacting neurones. GABA depolarized BLBP(+) progenitors via GABA transporter-3 (GAT3) and/or GABA(A) receptors. In CC-contacting neurones, GABA(A) receptor activation generated responses ranging from excitation to inhibition. This functional heterogeneity appeared to originate from different ratios of activity of the Na(+)-K(+)-2Cl(-) co-transporter (NKCC1) and the K(+)-Cl(-) co-transporter (KCC2). In both progenitors and immature neurones, GABA induced an increase in intracellular Ca(2+) that required extracellular Ca(2+) and was blocked by the selective GABA(A) receptor antagonist gabazine. Our study shows that GABAergic signalling around the CC shares fundamental properties with those in the embryo and adult neurogenic niches, suggesting that GABA may be part of the mechanisms regulating the production and integration of neurones within operational spinal circuits in the turtle.

[Phenotypic characteristics and virulence factors in Aeromonas strains isolated from patients with diarrheic disease in Cuba]. / Caracterización fenotípica y factores de virulencia en cepas de Aeromonas aisladas de pacientes con enfermedad diarreica aguda en Cuba.

Fifty four strains of Aeromonas spp were isolated from patients with acute diarrheic episodes by using Aerokey II and Aeroesquema methods. In vitro antimicrobial susceptibility and virulence factors were analyzed. The most frequently isolated specie was Aeromonas caviae. Over 75% of strains exhibited resistance to penicillins and ce-phalosporins; for the other antibiotic groups resistance was under 20%. Twenty six strains (48.1 %) were multiresist-ant. At least one virulence factor among those evaluated in the study was present in 53 (98.1%) of the 54 strains.

Connexin 43 delimits functional domains of neurogenic precursors in the spinal cord.

The cells lining the central canal (CC) of the spinal cord derive from the ventral part of the neural tube and, in some vertebrates, are responsible for the functional recovery after spinal cord injury. The region that surrounds the CC in the turtle contains proliferating cells that seem to generate both glia and neurons. Understanding the biology of spinal progenitors with the potential to generate new neurons "in situ" is important for cell replacement therapies. Here, we aimed to identify and characterize precursor cells in the spinal cord of Trachemys dorbignyi. To evaluate the population of proliferating cells, 5-bromo-2'-deoxyuridine (BrdU) was injected every 4 h (50 microg/g, i.p.) during 24 h. We found BrdU(+) nuclei around the CC with a higher density in the lateral quadrants, in which whole-cell patch-clamp recordings showed extensive dye coupling of cells. Carbenoxolone (100 microM) increased the input resistance, suggesting strong gap junction coupling among precursors. The expression of brain lipid binding protein (a marker of a subtype of radial glia) and Pax6 matched the location of clusters, suggesting these cells belonged to a domain of neurogenic precursors. These domains were delimited by a high density of connexin 43 (Cx43) located on the endfeet of CC contacting cells. Our findings indicate that spinal precursors share basic properties with those in the embryo and neurogenic niches of the adult brain, and support a key role of functional clustering via Cx43 in spinal cord neurogenesis.