898 resultados para chelicerates, nervous system, development, axonal pathfinding, midline


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Nasopharyngeal colonization with methicillin-resistant Staphylococcus aureus (MRSA) often precedes the development of nosocomial infections. In order to identify risk factors for MRSA colonization, we conducted a case-case-control study, enrolling 122 patients admitted to a medical-surgical intensive care unit (ICU). All patients had been screened for nasopharyngeal colonization with S. aureus upon admission and weekly thereafter. Two case-control studies were performed, using as cases patients who acquired colonization with MRSA and methicillin-susceptible S. aureus (MSSA), respectively. For both studies, patients in whom colonization was not detected during ICU stay were selected as control subjects. Several potential risk factors were assessed in univariate and multivariable (logistic regression) analysis. MRSA and MSSA were recovered from nasopharyngeal samples from 27 and 10 patients, respectively. Independent risk factors for MRSA colonization were: length-of-stay in the ICU (Odds Ratio [OR]=1.12, 95%Confidence Interval[CI]=1.06-1.19, p<0.001) and use of ciprofloxacin (OR=5.05, 95%CI=1.38-21.90, p=0.015). The use of levofloxacin had a protective effect (OR=0.08, 95%CI=0.01-0.55, p=0.01). Colonization with MSSA was positively associated with central nervous system disease (OR=7.45, 95%CI=1.33-41.74, p=0.02) and negatively associated with age (OR=0.94, 95%CI=0.90-0.99, p=0.01). In conclusion, our study suggests a role for both cross-transmission and selective pressure of antimicrobials in the spread of MRSA.

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Sodium, potassium adenosine triphosphatase (Na,K-ATPase) is a membrane-bound enzyme that maintains the Na+ and K+ gradients used in the nervous system for generation and transmission of bioelectricity. Recently, its activity has also been demonstrated during nerve regeneration. The present study was undertaken to investigate the ultrastructural localization and distribution of Na,K-ATPase in peripheral nerve fibers. Small blocks of the sciatic nerves of male Wistar rats weighing 250-300g were excised, divided into two groups, and incubated with and without substrate, the para-nitrophenyl phosphate (pNPP). The material was processed for transmission electron microscopy, and the ultra-thin sections were examined in a Philips CNI 100 (TM) electron microscope. The deposits of reaction product were localized mainly on the axolemma, on axoplasmic profiles, and irregularly dispersed on the myelin sheath, but not in the unmyelinated axons. In the axonal membrane, the precipitates were regularly distributed on the cytoplasmic side. These results together with published data warrant further studies for the diagnosis and treatment of neuropathies with compromised Na,K-ATPase activity. (c) 2007 Elsevier Ltd. All rights reserved.

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Background: Artificial selection has resulted in animal breeds with extreme phenotypes. As an organism is made up of many different tissues and organs, each with its own genetic programme, it is pertinent to ask: How relevant is tissue in terms of total transcriptome variability? Which are the genes most distinctly expressed between tissues? Does breed or sex equally affect the transcriptome across tissues?Results: In order to gain insight on these issues, we conducted microarray expression profiling of 16 different tissues from four animals of two extreme pig breeds, Large White and Iberian, two males and two females. Mixed model analysis and neighbor - joining trees showed that tissues with similar developmental origin clustered closer than those with different embryonic origins. Often a sound biological interpretation was possible for overrepresented gene ontology categories within differentially expressed genes between groups of tissues. For instance, an excess of nervous system or muscle development genes were found among tissues of ectoderm or mesoderm origins, respectively. Tissue accounted for similar to 11 times more variability than sex or breed. Nevertheless, we were able to confidently identify genes with differential expression across tissues between breeds (33 genes) and between sexes (19 genes). The genes primarily affected by sex were overall different than those affected by breed or tissue. Interaction with tissue can be important for differentially expressed genes between breeds but not so much for genes whose expression differ between sexes.Conclusion: Embryonic development leaves an enduring footprint on the transcriptome. The interaction in gene x tissue for differentially expressed genes between breeds suggests that animal breeding has targeted differentially each tissue's transcriptome.

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The effect of protein-calorie malnutrition during gestation on the brain amino acids of rat pups was studied following nutritional recovery during lactation. The brain amino acids of rat pups born to dam rats malnourished during gestation were studied after these rat pups received proper nutrition during lactation. Pregnant rats were fed a 1% protein diet with total caloric intake restricted to half that of controls. After birth, the offspring of rats fed on deficient diets were nurtured up to the 28th day postpartum by foster mothers receiving adequate diets. At this time, the offspring were killed. The control group consisted of offspring from pregnant rats fed a diet with adequate protein (21%) and calories during the entire gestation and lactation period. Quantitation of brain amino acids in the pups at 28 days postpartum showed lower concentrations of essential and nonessential amino acids in the rats malnourished during gestation. Concentrations of histidine, glycine, and α-aminobutyric acids were all reduced. These findings demonstrate that the brains of rat pups malnourished during gestation show persistent decreases in specific brain amino acids after adequate postpartum nutrition.

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Autism constitutes one of the most important pathologies of the pervasive developmental disorders (PDDs). It has early age-onset and is characterized by delay and deviance of social, communicative and cognitive development. Today, the presence of genetic factors in its etiology is well known, with familial recurrence of autism and other psychiatric conditions. Autism does not have usual Mendelian inheritence and presents genetic heterogeneity. Strong association has been found between autism and the fragile X syndrome (FMR-1 gene) and with tuberous sclerosis (Bourneville's syndrome). However, many different chromosomal abnormalities were recently described in autistic patients, mainly of chromosome 7 and 15. There are some genes on 15q11-q13 whose products have expression in the central nervous system, mainly synapses, which are subunits of neurotransmitters or ion channels (UBE3A, GABRA5, GABRB3, GABRG3, CHRNA7 e ITO). Some regions of chromosome 7 also have important developmental genes, as EN-2 and HOXA, which act on central nervous system formation. There seems then to exist genes associated with autism etiology on chromosomes 7,15 and X. The detailed study of these chromosomes can produce knowledgment about the biological mechanisms involved in this disturbance.

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Objective - We determined the effects of losartan and PD 123319 (antagonists of the AT1 and AT2 angiotensin receptors, respectively), and [Sar1, Ala8] ANG II (a relatively peptide antagonist of angiotensin receptors) injected into the paraventricular nucleus (PVN) on water and 3% NaCl intake, and the diuretic, natriuretic, and pressor effects induced by administration of angiotensin II (ANG II) into the medial septal area (MSA) of conscious rats. Methods - Holtzman rats were used. Animals were anesthetized with tribromoethanol (20 mg) per 100 grams of body weight, ip. A stainless steel guide cannula was implanted into the MSA and PVN. All drugs were injected in 0.5-μl volumes for 10-15 seconds. Seven days after brain surgery, water and 3% NaCl intake, urine and sodium excretion, and arterial blood pressure were measured. Results - Losartan (40 nmol) and [Sar1, Ala8] ANG II (40 nmol) completely eliminated whereas PD 123319 (40 nmol) partially blocked the increase in water and sodium intake and the increase in arterial blood pressure induced by ANG II (10 nmol) injected into the MSA. The PVN administration of PD 123319 and [Sar1, Ala8] ANG II blocked whereas losartan attenuated the diuresis and natriuresis induced by MSA administration of ANG II. Conclusion - MSA involvement with PVN on water and sodium homeostasis and arterial pressure modulation utilizing ANGII receptors is suggested.

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This paper intend to review recent advances in our understanding of programmed cell death, or apoptosis, and discuss implications of these basic science advances in the development of causes and potential treatments of a variety of diseases of the head and neck. Conclusions: apoptosis is now understood to be important in the normal development and survival of all multicellular organism. Deregulation of this normally tighly controlled process underlies a variety of disease states, including neoplasia, autoimmune disease, and disorders of the central nervous system. A better understanding of this process and regulation may help otolaryngologists better understand diseases relevant to this specialty and will lead to improved therapeutic interventions.

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The so-called endocrine disruptors have been described as compounds which interfere with the estrogen action in their receptors and may exert a crucial role in the development of the reproductive tract and in the brain sexual differentiation. Thus, conducts and/or exposure to these drugs in the perinatal period that apparently do not endanger the neonate may cause side effects. During embrionary development, the gonads, through discharge of a small quantity of reproductive hormones, will guarantee the phenotype of male or female at birth, as well as actuate in specific areas sexual differentiation of the central nervous system. Several experimental models have shown an interference of drugs acting as endocrine disruptors in hypothalamic sexual differentiation. Thus, reproductive function is impaired by exposure to estrogen in the perinatal life of rats and the mechanisms involved in this effect are distinct for males and females. Perinatal exposure to drugs which may be considered endocrine disrupters may induce an incomplete masculinization and defeminization of the central nervous system. Alterations in these processes, if present, generally are perceived only at puberty or adult reproductive life. These later alterations may include anomalies in the process of fertility or in sexual behavior.

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The maintenance of the arterial pressure in normal levels is important for the homeostasis of body fluids. The central nervous system regulating sympathetic and parasympathetic autonomic efferent can adjust arterial pressure which allows animals or human to face different daily activities with the best performance. Different central areas are responsible for the control of autonomic discharges to cardiovascular system and many of them are also involved in the control of fluid electrolyte balance. One of these areas is the tissue surrounding the anteroventral third ventricle (AV3V region) localized in the forebrain and a main central site for angiotensin II receptors and osmoreceptors. The AV3V lesions impair the development of many models of experimental hypertension in rats and the pressor responses to different stimuli. Lesions of the AV3V region also reduce dipsogenic responses to angiotensin II, central cholinergic activation, water deprivation and increase in plasma osmolarity, atrial natriuretic peptide secretion produced by body fluid expansion and the increase in renal excretion to central cholinergic activation. Recent evidence also suggests the participation of AV3V region in pressor responses produced by the activation of medullary mechanisms.

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The control of the blood pressure depends on the activity of select groups of neurons present in the central nervous system. Evidence has demonstrated that the redox state (a balance between oxidizing and reducing species) is involved in the control of neuronal activity, which suggests that the redox state can influence the neuronal transmission within the central nervous system acting on the neuronal modulation of biological functions. For instance, the glutamatergic transmission may be widely affected by reactive oxygen species, oxidizing agents that have been extensively investigated due to their involvement in physiological and pathological processes. In the present article, we discuss the main experimental finds that support the hypothesis that reactive oxygen species have important role in physiological (and pathological) modulation of the cardiovascular function through alterations in the sympathetic and parasympathetic system. Therefore, reactive oxygen species can actively participate in the development of cardiovascular diseases like hypertension when the balance in the redox state is disrupted.

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Membrane fusion is an essential step in the entry of enveloped viruses into their host cells triggered by conformational changes in viral glycoproteins. We have demonstrated previously that modification of vesicular stomatitis virus (VSV) with diethylpyrocarbonate (DEPC) abolished conformational changes on VSV glycoprotein and the fusion reaction catalyzed by the virus. In the present study, we evaluated whether treatment with DEPC was able to inactivate the virus. Infectivity and viral replication were abolished by viral treatment with 0.5 mM DEPC. Mortality profile and inflammatory response in the central nervous system indicated that G protein modification with DEPC eliminates the ability of the virus to cause disease. In addition, DEPC treatment did not alter the conformational integrity of surface proteins of inactivated VSV as demonstrated by transmission electron microscopy and competitive ELISA. Taken together, our results suggest a potential use of histidine (His) modification to the development of a new process of viral inactivation based on fusion inhibition. © 2006 Elsevier B.V. All rights reserved.

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The hypothalamic-pituitary-adrenal (HPA) axis is important in regulating energy metabolism and in mediating responses to stressors, including increasing energy availability during physical exercise. In addition, glucocorticoids act directly on the central nervous system and influence behavior, including locomotor activity. To explore potential changes in the HPA axis as animals evolve higher voluntary activity levels, we characterized plasma corticosterone (CORT) concentrations and adrenal mass in four replicate lines of house mice that had been selectively bred for high voluntary wheel running (HR lines) for 34 generations and in four nonselected control (C) lines. We determined CORT concentrations under baseline conditions and immediately after exposure to a novel stressor (40 min of physical restraint) in mice that were housed without access to wheels. Resting daytime CORT concentrations were approximately twice as high in HR as in C mice for both sexes. Physical restraint increased CORT to similar concentrations in HR and C mice; consequently, the proportional response to restraint was smaller in HR than in C animals. Adrenal mass did not significantly differ between HR and C mice. Females had significantly higher baseline and postrestraint CORT concentrations and significantly larger adrenal glands than males in both HR and C lines. Replicate lines showed significant variation in body mass, length, baseline CORT concentrations, and postrestraint CORT concentrations in one or both sexes. Among lines, both body mass and length were significantly negatively correlated with baseline CORT concentrations, suggesting that CORT suppresses growth. Our results suggest that selection for increased locomotor activity has caused correlated changes in the HPA axis, resulting in higher baseline CORT concentrations and, possibly, reduced stress responsiveness and a lower growth rate. © 2007 by The University of Chicago. All rights reserved.

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Background: lead poisoning can have a negative impact on the neuropsychological functions, including language, due to the damage it causes to the developthent of the Central Nervous System. Aim: to verify the occurrence of language disorders in children who suffered from led poisoning and to verify the correlation between the lead concentration level in the blood and the language disorders presented by the children. Method: language evaluation of 20 preschoolers, with lead concentration level in the blood above 10μg/dl. Results: 13 children presented language impairment involving only phonology or more than one language subsystem. The statistical analysis indicated that no correlation exists between the severity of the language impairment and the concentration levels of lead. Conclusion: the number of children with language impairment indicates lead poisoning as a risk factor for the present alterations, even though other risk factors for language disorders were found and the absence of correlation between the investigated variables.

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Autism spectrum disorders are severe psychiatric diseases commonly identified in the population. They are diagnosed during childhood and the etiology has been much debated due to their variations and complexity. Onset is early and characterized as communication and social interaction disorders and as repetitive and stereotyped behavior. Austistic disorders may occur together with various genetic and chromosomal diseases. Several chromosomal regions and genes are implicated in the predisposition for these diseases, in particular those with products expressed in the central nervous system. There are reports of autistic and mentally handicapped patients with submicroscopic subtelomeric alterations at the distal end of the long arm of chromosome 2. Additionally, there is evidence that alterations at 2q37 cause brain malformations that result in the autistic phenotype. These alterations are very small and not identified by routine cytogenetics to which patients are normally submitted, which may result in an underestimation of the diagnosis. This study aimed at evaluating the 2q37 region in patients with autistic disorders. Twenty patients were studied utilizing the fluorescence in situ hybridization technique with a specific probe for 2q37. All of them were also studied by the GTC banding technique to identify possible chromosomal diseases. No alterations were observed in the 2q37 region of the individuals studied, and no patient presented chromosomal diseases. This result may be due to the small sample size analyzed. The introduction of routine analysis of the 2q37 region for patients with autistic disorders depends on further studies. ©FUNPEC-RP.

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Background and Purpose: The circadian rhythm of melatonin in saliva or plasma, or of the melatonin metabolite 6-sulfatoxymelatonin (a6MTs) in urine, is a defining feature of suprachiasmatic nucleus (SCN) function, the body's endogenous oscillatory pacemaker. The primary objective of this review is to ascertain the clinical benefits and limitations of current methodologies employed for detection and quantification of melatonin in biological fluids and tissues. Data Identification: A search of the English-language literature (Medline) and a systematic review of published articles were carried out. Study Selection: Articles that specified both the methodology for quantifying melatonin and indicated the clinical purpose were chosen for inclusion in the review. Data Extraction: The authors critically evaluated the methodological issues associated with various tools and techniques (e.g. standards, protocols, and procedures). Results of Data Synthesis: Melatonin measurements are useful for evaluating problems related to the onset or offset of sleep and for assessing phase delays or advances of rhythms in entrained individuals. They have also become an important tool for psychiatric diagnosis, their use being recommended for phase typing in patients suffering from sleep and mood disorders. Additionally, there has been a continuous interest in the use of melatonin as a marker for neoplasms of the pineal region. Melatonin decreases such as found with aging are or post pinealectomy can cause alterations in the sleep/wake cycle. The development of sensitive and selective methods for the precise detection of melatonin in tissues and fluids has increasingly been shown to have direct relevance for clinical decision making. Conclusions: Due to melatonin's low concentration, as well as the coexistence of numerous other compounds in the blood, the routine determination of melatonin has been an analytical challenge. The available evidence indicates however that these challenges can be overcome and consequently that evaluation of melatonin's presence and activity can be an accessible and useful tool for clinical diagnosis. © Springer-Verlag 2010.