New insights into the antiviral activity of nordihydroguaiaretic acid: Inhibition of dengue virus serotype 1 replication

BACKGROUND

Dengue virus (DENV) is considered one of the most important pathogens in the world causing 390 million infections each year. Currently, the development of vaccines against DENV presents some shortcomings and there is no antiviral therapy available for its infection. An important challenge is that both treatments and vaccines must be effective against all four DENV serotypes. Nordihydroguaiaretic acid (NDGA), isolated from Larrea divaricata Cav. (Zygophyllaceae) has shown a significant inhibitory effect on a broad spectrum of viruses, including DENV serotypes 2 and 4.

PURPOSE

We evaluated the in vitro virucidal and antiviral activity of NDGA on DENV serotype 1 (DENV1), including the study of its mechanism of action, to provide more evidence on its antiviral activity.

METHODS

The viability of viral particles was quantified by the plaque-forming unit reduction method. NDGA effects on DENV1 genome and viral proteins were evaluated by qPCR and immunofluorescence, respectively. Lysosomotropic activity was assayed using acridine orange and neutral red dyes.

RESULTS

NDGA showed in vitro virucidal and antiviral activity against DENV1. The antiviral effect would be effective within the first 2 h after viral internalization, when the uncoating process takes place. In addition, we determined by qPCR that NDGA decreases the amount of intracellular RNA of DENV1 and, by immunofluorescence, the number of cells infected. These results indicate that the antiviral effect of NDGA would have an intracellular mechanism of action, which is consistent with its ability to be incorporated into host cells. Considering the inhibitory activity of NDGA on the cellular lipid metabolism, we compared the antiviral effect of two inhibitors acting on two different pathways of this type of metabolism: 1) resveratrol that inhibits the sterol regulatory element of binding proteins, and 2) caffeic acid that inhibits the 5-lipoxygenase (5-LOX) enzyme. Only caffeic acid produced an inhibitory effect on DENV1 infection. We studied the lysosomotropic activity of NDGA on host cells and found, for the first time, that this compound inhibited the acidification of cell vesicles which would prevent DENV1 uncoating process.

CONCLUSION

The present work contributes to the knowledge of NDGA activity on DENV. We describe its activity on DENV1, a serotype different to those that have been already reported. Moreover, we provide evidence on which stage/s of the viral replication cycle NDGA exerts its effects. We suggest that the mechanism of action of NDGA on DENV1 is related to its lysosomotropic effect, which inhibits the viral uncoating process.

Lack of Cdk5 activity is involved on Dopamine Transporter expression and function: Evidences from an animal model of Attention-Deficit Hyperactivity Disorder

Attention deficit/Hyperactivity disorder (ADHD) is one of the most diagnosed psychiatric disorders nowadays. The core symptoms of the condition include hyperactivity, impulsiveness and inattention. The main pharmacological treatment consists of psychostimulant drugs affecting Dopamine Transporter (DAT) function. We have previously shown that genetically modified mice lacking p35 protein (p35KO), which have reduced Cdk5 activity, present key hallmarks resembling those described in animal models useful for studying ADHD. The p35KO mouse displays spontaneous hyperactivity and shows a calming effect of methylphenidate or amphetamine treatment. Interestingly, dopaminergic neurotransmission is altered in these mice as they have an increased Dopamine (DA) content together with a low DA turnover. This led us to hypothesize that the lack of Cdk5 activity affects DAT expression and/or function in this animal model. In this study, we performed biochemical assays, cell-based approaches, quantitative fluorescence analysis and functional studies that allowed us to demonstrate that p35KO mice exhibit decreased DA uptake and reduced cell surface DAT expression levels in the striatum (STR). These findings are supported by in vitro observations in which the inhibition of Cdk5 activity in N2a cells induced a significant increase in constitutive DAT endocytosis with a concomitant increase in DAT localization to recycling endosomes. Taken together, these data provide evidences regarding the role of Cdk5/p35 in DAT expression and function, thus contributing to the knowledge of DA neurotransmission physiology and also providing therapeutic options for the treatment of DA pathologies such as ADHD.

Ghrelin treatment leads to dendritic spine remodeling in hippocampal neurons and increases the expression of specific BDNF-mRNA species

Ghrelin (Gr) is an orexigenic peptide that acts via its specific receptor, GHSR-1a distributed throughout the brain, being mainly enriched in pituitary, cortex and hippocampus (Hp) modulating a variety of brain functions. Behavioral, electrophysiological and biochemical evidence indicated that Gr modulates the excitability and the synaptic plasticity in Hp. The present experiments were designed in order to extend the knowledge about the Gr effect upon structural synaptic plasticity since morphological and quantitative changes in spine density after Gr administration were analyzed "in vitro" and "in vivo". The results show that Gr administered to hippocampal cultures or stereotactically injected in vivo to Thy-1 mice increases the density of dendritic spines (DS) being the mushroom type highly increased in secondary and tertiary extensions. Spines classified as thin type were increased particularly in primary extensions. Furthermore, we show that Gr enhances selectively the expression of BDNF-mRNA species.

Human Metapneumovirus: Epidemiology and genotype diversity in children and adult patients with respiratory infection in Córdoba, Argentina

Human Metapneumovirus (hMPV) is responsible for acute respiratory infections in humans, with clinical and epidemiological relevance in pediatric, elderly, and immunocompromised populations. These features are largely unknown in Córdoba, Argentina and in adults in general. Hence, our goal was to broadly characterize hMPV infection in patients of all ages hospitalized with acute respiratory infections in Córdoba, Argentina, including epidemiology, clinical features and genetic diversity. Nasopharyngeal secretions were obtained from 795 patients during 2011-2013, 621 patients were 0-25 years old and 174 were 26-85 years old. HMPV was assayed by RT-PCR and other respiratory viruses by indirect immunofluorescence. Local strains were identified by sequence analysis. Human Metapneumovirus was detected in 20.3% (161/795) patients, 13.1% as single infections and 7.2% in co-infections, more frequently with Respiratory Syncytial Virus. HMPV circulated during late winter and spring in all age patients, but mainly in children under 4 years old in 71.4% (115/161) and adults between 26 and 59 years old in 12.4% (20/161). The most prevalent diagnosis was mild acute respiratory infection in 59.6% (96/161) and bronchiolitis in 9.3% (15/161). Local strains were clustered within A2 subtype; they presented 73-100% identities among them, showing a high degree of homology compared to isolations from neighboring countries. We demonstrate that hMPV circulated among all age patients with respiratory infection during 2011-2013 in Córdoba, contributing to the understanding of this virus, its diagnosis and patient handling in local health-care centers.

Long-term impact of chronic variable stress in adolescence versus adulthood

Adolescence is a period of active development of stress regulatory neurocircuitry. As a consequence, mechanisms that control the responses to stress are not fully matured during this developmental period, which may result in vulnerability to chronic stress. We hypothesized that adolescent chronic stress would have negative consequences on stress adaptation later in life. Male Wistar rats (PND40) were subjected to chronic variable stress (CVS) for 2 weeks, with 2 daily stressors randomly presented and overnight social stressors twice a week. After five weeks, animals were evaluated during adulthood, using the elevated plus maze (EPM) and the forced swim test (FST). The hypothalamic-pituitary adrenal (HPA) axis response to a 30-min restraint was also assessed. Results are compared to those of adult rats tested 5 weeks following CVS cessation. Our results demonstrate that the long-term effects of CVS are specific to the age of application of the stress regime. We show how behavior and HPA axis response as well as hypothalamic paraventricular nucleus activation can differ with age, resulting in differential behavioral adaptations for animals stressed in adolescence and dysregulation of the HPA axis in the animals stressed in adulthood, These data underscore the importance of the adolescent period in determining resilience of the HPA axis and programming behavioral responses later in life.

[Monoinfection of human Metapneumovirus in Cordoba: first clinical and epidemiological research in children with respiratory infection in 2011]

Human metapneumovirus (hMPV) RNA virus discovered in 2001, is a pathogen associated with acute respiratory infection (ARI) in children under 5 years; its prevalence ranges from 5-15%. In Córdoba, it is not integrated into the viral research in patients with low IRA (LARI).

OBJECTIVE

Detect hMPV in children under 5 years hospitalized for LARI in the Children's Hospital "Santísima Trinidad" of Cordoba (HNC) in 2011 and describe the clinical and epidemiological characteristics of monoinfecciones without comorbidity.

POPULATION AND METHOD

Prospective, observational study. It includes (informed consent) children under 5 years with LARI of HNC from January to December 2011. The viral detection was performed using immunofluorescence of nasopharyngeal aspirate secretions. Demographic, epidemiological and clinical data of positive cases were recorded.

RESULTS

Of 223 patients enrolled, respiratory viruses were detected in 74 (33.2%). HMPV prevalence was 4.04% (9/223), representing the 2nd place with Parainfluenza 3 (4.04%) after RSV (19.73%). Season from July to December. The average age for hMPV was 7.4 ± 6.8 months (0-60 months), 4/9 males. The average hospital stay in days was 5.6 ± 0.5 and prodrome days: 1.9 days ± 0.6. All patients require oxygen therapy (3.9 ± 1.3 days) without mechanical ventilation. Diagnosis of bronchiolitis cases occurred in 5/9 and 4/9 pneumonia. No complications at discharge.

CONCLUSIONS

First report to document the presence of hMPV in child population of Cordoba. Its prevalence in 2011 was 4, 04%. Among monoinfecciones no fatalities or complications at discharge were recorded.

Context-dependent latent inhibition in preweanling rats

Preexposure to a conditioned stimulus (CS) usually weakens conditioning, an effect known as latent inhibition. Similar to other learning interference effects, latent inhibition has been characterized as context-dependent, which means that the magnitude of this effect can be attenuated by changing the context between the different phases of the procedure (e.g., preexposure and conditioning). Latent inhibition has been found with a variety of procedures in infant rats, but the few studies that examined the context-dependency of this phenomenon during this ontogenetic period found no context-change effect. The present study explored the context-dependency of latent inhibition during infancy using a conditioned taste aversion preparation and employing contexts enriched with distinctive odors to increase the possible efficacy of the context manipulation. Experiment 1 showed that three preexposures to the CS (saccharin) were sufficient to retard conditioning to the same CS, although this effect was also observed in a control group preexposed to an alternative taste stimulus (saline), in comparison with a non-preexposed control group. In Experiment 2a, the CS-preexposure effect was found to be specific to the preexposed CS when the number of preexposures was increased. This effect was revealed as context-dependent in Experiment 2b, since it was attenuated by changing the context between preexposure and conditioning. The present result is consistent with recent studies showing the context-dependency of extinction in preweanling rats, thus demonstrating these animals' capacity to learn about context early on in their development.

Fibronectin substrate induces shortening of in vitro neural crest cell mitotic cycle

Neural crest cells (NCC) segregate from neural folds, swim through extracellular matrix, and differentiate in several cell types. During in vivo and in vitro dispersion, NCC display a substantial proliferative rate. Here, we have evaluated this biological behavior under the influence of different substrates. NCC exhibit the highest proliferative activity on fibronectin substrate, with shortening of the G1 period. This fact is reverted by specific antibody pre-treatment of the substrate. Taking into account that NCC migrate along narrow and restricted pathways rich in essential fibronectin, with high proliferative rates, these results indicate that the fibronectin pathway contributes to increase the cell number, leading to a high population pressure that could participate in the early dispersion of NCC.

Method for treating and processing whole chick embryos for autoradiography, immunocytochemistry and other techniques

A method is presented for in situ treatment of whole chick embryos with drugs and immunocytochemical and fixative reagents that resembles conditions "in ovo." The chick embryo is placed in a "shell-less" culture system where it is contained by an agar ring allowing for treatment in vivo. The conceptus (embryo+membranes) is then mounted on a microporous membrane and inserted into a filter device connected to a three-way stopcock that permits fluids to be changed using syringes. The embryo is then processed in toto or after embedding and sectioning for light or electron microscopy. The proposed handling system decreases technical artifacts and changes in the topographic microanatomy produced by conventional manipulation of chick embryos. This method is useful also for directly observing and recording changes in the embryo during drug treatments and allows processing with dangerous reagents without their direct contact with the operator. It is simple, inexpensive and requires only minimal technical training.