Chronic Treatment with Paraquat Induces Brain Injury,Changes in Antioxidant Defenses System,and Modulates Behavioral Functions in Zebrafish

Paraquat (PQ) administration consists in a chemical model that mimics phenotypes observed in Parkinson’s disease (PD), due to its ability to induce changes in dopaminergic system and oxidative stress. The aim of this study was to evaluate the actions of PQ in behavioral functions of adult zebrafish and its influence on oxidative stress biomarkers in brain samples. PQ (20 mg/kg) was administered intraperitoneally with six injections for 16 days (one injection every 3 days). PQ-treated group showed a significant decrease in the time spent in the bottom section and a shorter latency to enter the top area in the novel tank test. Moreover, PQ-exposed fish showed a significant decrease in the number and duration of risk assessment episodes in the light–dark test, as well as an increase in the agonistic behavior in the mirror-induced aggression (MIA) test. PQ induced brain damage by decreasing mitochondrial viability. Concerning the antioxidant defense system, PQ increased catalase (CAT) and glutathione peroxidase (GPx) activities, as well as the non-protein sulfhydryl content (NPSH), but did not change ROS formation and decreased lipid peroxidation. We demonstrate, for the first time, that PQ induces an increase in aggressive behavior, alters non-motor patterns associated to defensive behaviors, and changes redox parameters in zebrafish brain. Overall, our findings may serve as useful tools to investigate the interaction between behavioral and neurochemical impairments triggered by PQ administration in zebrafish.     

Optimization and clinical validation of a pathogen detection microarray

DNA microarrays used as 'genomic sensors' have great potential in clinical diagnostics. Biases inherent in random PCR-amplification, cross-hybridization effects, and inadequate microarray analysis, however, limit detection sensitivity and specificity. Here, we have studied the relationships between viral amplification efficiency, hybridization signal, and target-probe annealing specificity using a customized microarray platform. Novel features of this platform include the development of a robust algorithm that accurately predicts PCR bias during DNA amplification and can be used to improve PCR primer design, as well as a powerful statistical concept for inferring pathogen identity from probe recognition signatures. Compared to real-time PCR, the microarray platform identified pathogens with 94% accuracy (76% sensitivity and 100% specificity) in a panel of 36 patient specimens. Our findings show that microarrays can be used for the robust and accurate diagnosis of pathogens, and further substantiate the use of microarray technology in clinical diagnostics.     

Do plant functional types based on leaf dry matter content allow characterizing native grass species and grasslands for herbage growth pattern?

Few studies have focused on vegetation characteristics of importance to feeding domestic herbivores, mainly the seasonal pattern of herbage growth at spring. Our objective is to establish and to evaluate a simple method of ranking grassland communities for these characteristics. We combined approaches at plant species level (comparison of grass species growing in a pure stand) and plant community level (comparison of grasslands differing mainly in their nutrient availability). Firstly, we ask if the ranking of species by leaf dry matter content (LDMC), a functional parameter used to assess the plant strategy for resource acquisition and use, is consistent with a classification of the species using three plant features that determine plant growth pattern at spring (beginning and ending of stem elongation, leaf lifespan). Secondly, for three networks of natural grasslands, we test whether there is consistency when ranking them by their dominant plant functional type (PFT A, B or C) established previously at species level, and by the three agronomic characteristics. For species growing in pure stands, there was a significant effect of PFT for the three plant features. For species having a low LDMC (A and B PFT), there were earlier stem elongation in the season, earlier flowering and shorter leaf lifespan. The opposite was observed for species having a high LDMC (C and D PFT). For grassland communities dominated by A-PFT, the ceiling yield for leaves and stems occurred earlier in spring than for those dominated by C-PFT. Results were consistent at plant and community levels. Scaling up from plant to community was well mediated by PFT. Plant features which characterize species for resource acquisition and use are consistent with herbage growth patterns at plant community level. These results show that herbage growth pattern and composition depend on PFTs and that knowing the PFT dominance is of great importance to plan the use of grasslands. We can expect to use the PFT approach to perform vegetation diagnosis at field level when the objective is to rank grassland communities for their agronomic characteristics. Fernando L. F. de Quadros was supported by CAPES and CNPq (BP-2).     

Tissue distribution of endogenous cobalamins and other corrins in the rat, cat and guinea pig.

1. Methylcobalamin, adenosylcobalamin, hydroxocobalamin and cyanocobalamin have been estimated by a chromato-bioautographic techniques in 16 tissues from healthy rats and in five guinea pig tissues. 2. Plasma and erythrocyte cobalamins have been estimated in rats, cats and guinea pigs and the results compared with those in man. 3. Unidentified corrins were detected in 8 of the 16 rat tissues and in 3 of the 5 guinea pig tissues analysed, but were not present in tissues from specific pathogen-free rats nor in the standard laboratory diet. 4. Adenosylcobalamin was the major corrin in 8 of the 16 rat tissues. In the remainder hydroxocobalamin predominated or was present in equal proportions with adenosylcobalamin. Methylcobalamin was detected in the majority of rat tissues but at levels much lower than those in human tissues. Small amounts of cyanocobalamin were detected also and levels were higher than those of methylcobalamin in 8 of the 16 tissues. 5. In the rat, cat and guinea pig, levels of methylcobalamin and hydroxobalamin were higher in erythrocytes than in plasma, a pattern almost the complete reverse of that in man.     

Biomechanical spinal growth modulation and progressive adolescent scoliosis – a test of the 'vicious cycle' pathogenetic hypothesis: Summary of an electronic focus group debate of the IBSE

There is no generally accepted scientific theory for the causes of adolescent idiopathic scoliosis (AIS). As part of its mission to widen understanding of scoliosis etiology, the International Federated Body on Scoliosis Etiology (IBSE) introduced the electronic focus group (EFG) as a means of increasing debate on knowledge of important topics. This has been designated as an on-line Delphi discussion. The text for this debate was written by Dr Ian A Stokes. It evaluates the hypothesis that in progressive scoliosis vertebral body wedging during adolescent growth results from asymmetric muscular loading in a "vicious cycle" (vicious cycle hypothesis of pathogenesis) by affecting vertebral body growth plates (endplate physes). A frontal plane mathematical simulation tested whether the calculated loading asymmetry created by muscles in a scoliotic spine could explain the observed rate of scoliosis increase by measuring the vertebral growth modulation by altered compression. The model deals only with vertebral (not disc) wedging. It assumes that a pre-existing scoliosis curve initiates the mechanically-modulated alteration of vertebral body growth that in turn causes worsening of the scoliosis, while everything else is anatomically and physiologically 'normal' The results provide quantitative data consistent with the vicious cycle hypothesis. Dr Stokes' biomechanical research engenders controversy. A new speculative concept is proposed of vertebral symphyseal dysplasia with implications for Dr Stokes' research and the etiology of AIS. What is not controversial is the need to test this hypothesis using additional factors in his current model and in three-dimensional quantitative models that incorporate intervertebral discs and simulate thoracic as well as lumbar scoliosis. The growth modulation process in the vertebral body can be viewed as one type of the biologic phenomenon of mechanotransduction. In certain connective tissues this involves the effects of mechanical strain on chondrocytic metabolism a possible target for novel therapeutic intervention.     

Exposure to Folate Receptor Alpha Antibodies during Gestation and Weaning Leads to Severe Behavioral Deficits in Rats: A Pilot Study

The central nervous system continues to develop during gestation and after birth, and folate is an essential nutrient in this process. Folate deficiency and folate receptor alpha autoantibodies (FRα-AuAb) have been associated with pregnancy-related complications and neurodevelopmental disorders. In this pilot study, we investigated the effect of exposure to FRα antibodies (Ab) during gestation (GST), the pre-weaning (PRW), and the post weaning (POW) periods on learning and behavior in adulthood in a rat model. In the open field test and novel object recognition task, which examine locomotor activity and anxiety-like behavior, deficits in rats exposed to Ab during gestation and pre-weaning (GST+PRW) included more time spent in the periphery or corner areas, less time in the central area, frequent self-grooming akin to stereotypy, and longer time to explore a novel object compared to a control group; these are all indicative of increased levels of anxiety. In the place avoidance tasks that assess learning and spatial memory formation, only 30% of GST+PRW rats were able to learn the passive place avoidance task. None of these rats learned the active place avoidance task indicating severe learning deficits and cognitive impairment. Similar but less severe deficits were observed in rats exposed to Ab during GST alone or only during the PRW period, suggesting the extreme sensitivity of the fetal as well as the neonatal rat brain to the deleterious effects of exposure to Ab during this period. Behavioral deficits were not seen in rats exposed to antibody post weaning. These observations have implications in the pathology of FRα-AuAb associated with neural tube defect pregnancy, preterm birth and neurodevelopmental disorders including autism.     

Studies of genotoxicity and mutagenicity of nitroimidazoles: demystifying this critical relationship with the nitro group

Nitroimidazoles exhibit high microbicidal activity, but mutagenic, genotoxic and cytotoxic properties have been attributed to the presence of the nitro group. However, we synthesised nitroimidazoles with activity against the trypomastigotes of Trypanosoma cruzi, but that were not genotoxic. Herein, nitroimidazoles (11-19) bearing different substituent groups were investigated for their potential induction of genotoxicity (comet assay) and mutagenicity (Salmonella/Microsome assay) and the correlations of these effects with their trypanocidal effect and with megazol were investigated. The compounds were designed to analyse the role played by the position of the nitro group in the imidazole nucleus (C-4 or C-5) and the presence of oxidisable groups at N-1 as an anion receptor group and the role of a methyl group at C-2. Nitroimidazoles bearing NO2 at C-4 and CH3 at C-2 were not genotoxic compared to those bearing NO₂ at C-5. However, when there was a CH3 at C-2, the position of the NO2 group had no influence on the genotoxic activity. Fluorinated compounds exhibited higher genotoxicity regardless of the presence of CH3 at C-2 or NO2 at C-4 or C-5. However, in compounds 11 (2-CH3; 4-NO2; N-CH2OHCH2Cl) and 12 (2-CH3; 4-NO2; N-CH2OHCH2F), the fluorine atom had no influence on genotoxicity. This study contributes to the future search for new and safer prototypes and provide.     

Progesterone reduces erectile dysfunction in sleep-deprived spontaneously hypertensive rats

Background  

Paradoxical sleep deprivation (PSD) associated with cocaine has been shown to enhance genital reflexes (penile erection-PE and ejaculation-EJ) in Wistar rats. Since hypertension predisposes males to erectile dysfunction, the aim of the present study was to investigate the effects of PSD on genital reflexes in the spontaneously hypertensive rat (SHR) compared to the Wistar strain. We also extended our study to examine how PSD affect steroid hormone concentrations involved in genital events in both experimental models.     

ROCK1 is a potential combinatorial drug target for BRAF mutant melanoma

Treatment of BRAF mutant melanomas with specific BRAF inhibitors leads to tumor remission. However, most patients eventually relapse due to drug resistance. Therefore, we designed an integrated strategy using (phospho)proteomic and functional genomic platforms to identify drug targets whose inhibition sensitizes melanoma cells to BRAF inhibition. We found many proteins to be induced upon PLX4720 (BRAF inhibitor) treatment that are known to be involved in BRAF inhibitor resistance, including FOXD3 and ErbB3. Several proteins were down‐regulated, including Rnd3, a negative regulator of ROCK1 kinase. For our genomic approach, we performed two parallel shRNA screens using a kinome library to identify genes whose inhibition sensitizes to BRAF or ERK inhibitor treatment. By integrating our functional genomic and (phospho)proteomic data, we identified ROCK1 as a potential drug target for BRAF mutant melanoma. ROCK1 silencing increased melanoma cell elimination when combined with BRAF or ERK inhibitor treatment. Translating this to a preclinical setting, a ROCK inhibitor showed augmented melanoma cell death upon BRAF or ERK inhibition in vitro. These data merit exploration of ROCK1 as a target in combination with current BRAF mutant melanoma therapies.