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Background: Mucopolysaccharidosis type VI (MPS VI) is a progressive, chronic and multisystem lysosomal storage disease with a wide disease spectrum. Clinical and biochemical improvements have been reported for MPS VI patients on enzyme replacement therapy (ERT) with rhASB (recombinant human arylsulfatase B; galsulfase, Naglazyme®, BioMarin Pharmaceutical Inc.), making early diagnosis and intervention imperative for optimal patient outcomes. Few studies have included children younger than five years of age. This report describes 34 MPS VI patients that started treatment with galsulfase before five years of age., Methods: Data from patients who initiated treatment at <5 years of age were collected from patients' medical records. Baseline and follow-up assessments of common symptoms that led to diagnosis and that were used to evaluate disease progression and treatment efficacy were evaluated., Results: A significant negative correlation was seen with treatment with ERT and urinary GAG levels. Of those with baseline and follow-up growth data, 47% remained on their pre-treatment growth curve or moved to a higher percentile after treatment. Of the 9 patients with baseline and follow-up sleep studies, 5 remained unaffected and 1 patient initially with mild sleep apnea showed improvement. Data regarding cardiac, ophthalmic, central nervous system, hearing, surgical interventions and development are also reported. No patient discontinued treatment due to an adverse event and all that were treatment-emergent resolved., Conclusions: The prescribed dosage of 1mg/kg IV weekly with galsulfase ERT is shown to be safe and effective in slowing and/or improving certain aspects of the disease, although patients should be closely monitored for complications associated with the natural history of the disease, especially cardiac valve involvement and spinal cord compression. A long-term follow-up investigation of this group of children will provide further information on the benefits of early treatment as well as disease progression and treatment efficacy and safety in this young patient population., (Copyright © 2013 Elsevier Inc. All rights reserved.)

Aim: Evaluate the IS6110-Taqman system performance in sputum samples from patients with pulmonary tuberculosis from health services in north-eastern Brazil as a diagnostic laboratory tool for pulmonary tuberculosis., Methods and Results: 165 sputum samples from respiratory symptomatic patients were evaluated in the IS6110-TaqMan assay: 66 patients with pulmonary tuberculosis and 99 without TB. When the IS6110-TaqMan assay was evaluated using culture and/or clinical response to the specific treatment as the gold standard, IS6110-TaqMan assay obtained a sensitivity of 87.9% and specificity of 98%. The performance of IS6110-TaqMan assay was also evaluated with the sputum smear microscopy, resulting in a sensitivity of 79.7% and specificity 94.8%., Conclusions: The IS6110-TaqMan was rapid, sensitive and specific for the diagnosis of pulmonary TB., Significance and Impact of the Study: IS6110-TaqMan assay is a promising auxiliary tool for the diagnosis of pulmonary TB when used in conjunction with routine laboratory tests, clinical and epidemiological criteria of the patient, thus increasing the sensitivity and specificity of diagnosis., (© Aggeu Magalhães Research Center © 2012 The Society for Applied Microbiology.)

Unlabelled: The current scientific literature reports on the incidence of hearing impairments due to HIV/AIDS, and the hearing changes can occur due to damage to the outer, middle or inner ear. Thus, it is important to study how these changes occur, the hearing loss and their associations with the HIV/AIDS infection., Objective: To identify the factors related to hearing loss in people with HIV/AIDS in the global scientific literature., Method: Study carried out an Integrative Review of the Literature. The key words used were: hearing loss, hearing disorders and deafness, separately associated to the keyword HIV on PUBMED, SciELO, LILACS and ISI databases. We used complete original papers, of free access, in English, Spanish, French and Portuguese. Thirteen quantitative studies from 1994-2010 were selected., Conclusion: We did not find any strong direct association between anti-retroviral therapy and hearing loss; however, there are indications of hearing loss in the population studied, and their associations and causes need to be better investigated.

The authors report a case of a 12-year-old child with a complaint of pain and deformity in the lower thoracic region that had lasted for two years. Clinical, epidemiological and laboratory characteristics associated with images of apparent damage in the T9-T10 and T11-T12 vertebrae taken by radiography of the thoracic spine and nuclear magnetic resonance in addition to the positivity of the molecular test based on the polymerase chain reaction, led to tuberculous spondylitis being diagnosed and specific therapy was started. Culture of vertebral biopsy was positive for Mycobacterium tuberculosis after thirty days.

The Mongolian gerbil (Meriones unguiculatus, Gerbilinae: Muridae) is useful for prostate studies, because both males and females spontaneously develop prostatic disorders with age. Estrogens regulate prostate homeostasis via two estrogen receptors, ER alpha (ESR1) and ER beta (ESR2), but the cellular distribution and regulation of these receptors in the gerbil prostate has not been described. Both receptors were localized by immunohistochemistry in the ventral prostate of intact male and female gerbils, in males 7 and 21 days after castration, and in females treated with testosterone for 7 and 21 days. In male and female adult gerbils, ER alpha was detected mainly in prostatic stromal cells, whereas ER beta was present mostly in secretory and basal cells. More ER alpha-positive stromal cells were found in females than in males, as was a reduction toward the male value in females treated with testosterone. Castration did not alter ER alpha expression. Testosterone was necessary for maintenance of ER beta in the male prostate epithelium: ER beta expression declined markedly in prostates of males older than 1 yr, and castration of 4-mo-old males caused a reduction in ER beta to levels seen in 1-yr-old males. Because ER beta is an antiproliferative receptor, its loss with age may predispose the aging gerbil to proliferative diseases of the prostate.

The conundrum of cooperation has received increasing attention during the last decade. In this quest, the role of altruistic punishment has been identified as a mechanism promoting cooperation. Here we investigate the role of altruistic punishment on the emergence and maintenance of cooperation in structured populations exhibiting connectivity patterns recently identified as key elements of social networks. We do so in the framework of Evolutionary Game Theory, employing the Prisoner's Dilemma and the Stag-Hunt metaphors to model the conflict between individual and collective interests regarding cooperation. We find that the impact of altruistic punishment strongly depends on the ratio q/p between the cost of punishing a defecting partner (q) and the actual punishment incurred by the partner (p). We show that whenever q/p<1, altruistic punishment turns out to be detrimental for cooperation for a wide range of payoff parameters, when compared to the scenario without punishment. The results imply that while locally, the introduction of peer punishment may seem to reduce the chances of free-riding, realistic population structure may drive the population towards the opposite scenario. Hence, structured populations effectively reduce the expected beneficial contribution of punishment to the emergence of cooperation which, if not carefully dosed, may in fact hinder the chances of widespread cooperation.

Many problems in nature can be conveniently framed as a problem of evolution of collective cooperative behaviour, often modelled resorting to the tools of evolutionary game theory in well-mixed populations, combined with an appropriate N-person dilemma. Yet, the well-mixed assumption fails to describe the population dynamics whenever individuals have a say in deciding which groups they will participate. Here we propose a simple model in which dynamical group formation is described as a result of a topological evolution of a social network of interactions. We show analytically how evolutionary dynamics under public goods games in finite adaptive networks can be effectively transformed into a N-Person dilemma involving both coordination and co-existence. Such dynamics would be impossible to foresee from more conventional 2-person interactions as well as from descriptions based on infinite, well-mixed populations. Finally, we show how stochastic effects help rendering cooperation viable, promoting polymorphic configurations in which cooperators prevail.

When starting a new collaborative endeavor, it pays to establish upfront how strongly your partner commits to the common goal and what compensation can be expected in case the collaboration is violated. Diverse examples in biological and social contexts have demonstrated the pervasiveness of making prior agreements on posterior compensations, suggesting that this behavior could have been shaped by natural selection. Here, we analyze the evolutionary relevance of such a commitment strategy and relate it to the costly punishment strategy, where no prior agreements are made. We show that when the cost of arranging a commitment deal lies within certain limits, substantial levels of cooperation can be achieved. Moreover, these levels are higher than that achieved by simple costly punishment, especially when one insists on sharing the arrangement cost. Not only do we show that good agreements make good friends, agreements based on shared costs result in even better outcomes.

In many real-life situations, the completion of a task by a group toward achieving a common goal requires the cooperation of at least some of its members, who share the required workload. Such cases are conveniently modeled by the N-person snowdrift game, an example of a Public Goods Game. Here we study how an underlying network of contacts affects the evolutionary dynamics of collective action modeled in terms of such a Public Goods Game. We analyze the impact of different types of networks in the global, population-wide dynamics of cooperators and defectors. We show that homogeneous social structures enhance the chances of coordinating toward stable levels of cooperation, while heterogeneous network structures create multiple internal equilibria, departing significantly from the reference scenario of a well-mixed, structureless population., (Copyright © 2012 Elsevier Ltd. All rights reserved.)

Suspicion of Brazilian spotted fever (BSF) should occur in endemic regions upon surveillance of the acute febrile icteric hemorrhagic syndrome (AFIHS). However, limitations associated with currently available laboratory tests pose a challenge to early diagnosis, especially in fatal cases. Two real-time PCR (qPCR) protocols were evaluated to diagnose BSF in 110 fatal AFIHS cases, collected in BSF-endemic regions in 2009-2010. Of these, 24 were positive and 86 negative by indirect immunofluorescence (IFA) assay (cut-off IgG and/or IgM ≥ 128). DNA from these samples was used in the qPCR protocols: one to detect Rickettsia spp. (citrate synthase gene) and another to determine spotted fever group (SFG) Rickettsia species (OmpA gene). Of the 24 IFA-positive samples, 5 (21%) were positive for OmpA and 9 (38%) for citrate synthase. In the IFA-negative group (n=86), OmpA and citrate synthase were positive in 23 (27%) and 27 (31%), respectively. These results showed that the 2 qPCR protocols were about twice as sensitive as the IFA test alone (93% concordance). In conclusion, qPCR is a sensitive method for the diagnosis of fatal BSF cases and should be considered for routine surveillance of AFIHS in places like Brazil, where spotted fever-related lethality is high and other endemic diseases like dengue and leptospirosis can mislead diagnosis., (Copyright © 2012 Elsevier GmbH. All rights reserved.)

Background: Takayasu arteritis (TA) is a rare chronic granulomatous inflammatory disease of the aorta and/or its major branches and more frequently affects female patients before menopause. Since persistent inflammation may lead to arterial ischemia, hypertension is an important complication of TA., Objectives: To evaluate gestational results and complications in patients with TA., Methods: We conducted a retrospective analysis of the medical records of patients with TA admitted to the high risk pregnancy clinic for women with systemic autoimmune diseases at Hospital Universitário Pedro Ernesto., Results: From 1998 to 2011 we followed 11 pregnancies in 9 patients with TA; the patients' age ranged from 17 to 42 years and disease duration from 2 to 28 years. In 7 of the 11 pregnancies, uncontrolled blood pressure occurred before labor and preeclampsia was diagnosed in one. Two deliveries were preterm, one newborn was treated for sepsis, and four (36%) had intrauterine growth restriction (IUGR)., Conclusions: Close monitoring improves the perinatal outcomes in patients with TA who are more prone to develop hypertension, preeclampsia and IUGR. Disease activity was not observed in our group of patients during pregnancy. Coordinated care between the obstetric, rheumatologic and cardiologic teams is the ideal setting to follow pregnant women with TA.

Brazilian spotted fever (BSF) caused by Rickettsia rickettsii is the most important rickettsiosis and the only reportable tick-borne disease in Brazil. In Brazil, the hard tick Amblyomma cajennense is the most important BSF vector; however, in São Paulo State, A. aureolatum was also recognized as a vector species in remaining Atlantic forest areas near the metropolitan area of São Paulo city. We analyzed clinical and epidemiological features of BSF cases from two distinct areas where A. cajennense (Area 1) and A. aureolatum (Area 2) are the incriminated vectors. The clinical features demonstrate the same severity pattern of BSF in both endemic areas. Differences in seasonality, patient characteristics (median age and gender), and epidemiological risk factors (animals host contact and vegetation characteristics) were observed and possibly could be attributed to the characteristics of each vector and their typical biological cycle (hosts and environment)., (Copyright © 2012 Elsevier GmbH. All rights reserved.)

Protein malnutrition after weaning changes the neurotransmission in neural pathways that organize cardiovascular reflexes in rats. The present study evaluates whether protein malnutrition alters the expression of c-fos protein (immediate-early gene expression) in central areas involved in the control of cardiovascular reflexes after intermittent stimulation of the baroreflex. The main nuclei we focused were paraventricular hypothalamus (PVH); nucleus tract solitarii (NTS); rostral ventromedial medulla (RVMM); rostral (RVLM) and caudal ventrolateral medulla (CVLM). Male Fisher rats at 28 days were submitted to two different isocaloric diets during the subsequent 35 days: control (CT) (15% protein) and malnourished (MN) (6% protein). thirtymin of intermittent (every 3 min) baroreflex stimulation was performed by infusing phenylephrine (Phe-0.25 mM) or, as control, 0.9% NaCl (Sal). Following ninety minutes, animals were anesthetized and perfused. The removed brains were sectioned (35 μm) and used for c-fos immunohistochemistry. Images were analyzed using the software Leica Q Win. Despite not altering the baseline MAP, malnutrition increased baseline HR and expression of c-fos in RVMM. Increases in c-fos expression after intermittent stimulation of baroreflex were evident in the PVH, medial NTS and CVLM in both dietary protocols. Current data further revealed a differential neuronal recruitment to stimulation of baroreflex in the caudal commissural and rostral NTS and RVLM of MN. We conclude that protein malnutrition modifies the cardiovascular control and the pattern of central response to baroreflex stimulation., (Copyright © 2012 Elsevier B.V. All rights reserved.)

The development of the prostate depends on a precise androgenic control, so sensible interferences may predispose this gland to develop prostatic diseases during life. These aspects are of interest and preoccupation, since human beings are exposed to a growing number of endocrine-disrupting chemicals with androgenic potential. Therefore, our aim was to evaluate the prostates of adult gerbils exposed to testosterone during intrauterine life. Serological, morphological, morphometric-stereologic, immunohistochemical and three-dimensional reconstruction analyses were used. We found that the testosterone effects were dose-dependent and more harmful to females, leading to the development of masculine characteristics, evidenced by an increased anogenital distance, and absence of vaginal opening and the ectopic development of prostatic tissue. Moreover, premalignant lesions, such as prostatic intraepithelial neoplasia, were observed in addition to inflammatory foci in the prostate. The results showed that the prenatal exposure to testosterone may affect the reproductive system, disrupting developmental processes and increasing susceptibility to the development of prostatic diseases in the Mongolian gerbil.

Intention recognition is ubiquitous in most social interactions among humans and other primates. Despite this, the role of intention recognition in the emergence of cooperative actions remains elusive. Resorting to the tools of evolutionary game theory, herein we describe a computational model showing how intention recognition coevolves with cooperation in populations of self-regarding individuals. By equipping some individuals with the capacity of assessing the intentions of others in the course of a prototypical dilemma of cooperation-the repeated prisoner's dilemma-we show how intention recognition is favored by natural selection, opening a window of opportunity for cooperation to thrive. We introduce a new strategy (IR) that is able to assign an intention to the actions of opponents, on the basis of an acquired corpus consisting of possible plans achieving that intention, as well as to then make decisions on the basis of such recognized intentions. The success of IR is grounded on the free exploitation of unconditional cooperators while remaining robust against unconditional defectors. In addition, we show how intention recognizers do indeed prevail against the best-known successful strategies of iterated dilemmas of cooperation, even in the presence of errors and reduction of fitness associated with a small cognitive cost for performing intention recognition.

There is an increasing variety of endocrine disrupting chemicals (EDCs) either with (anti)estrogenic or (anti)androgenic potential widely present in the environment. These xenosteroids may mimic endogenous steroid hormones disrupting the homeostasis of physiological pathways and leading to several disturbances, especially in tissues highly dependent on steroid hormones such as the prostate. Taking this into account, this comparative study aimed to verify the potential of ethinylestradiol (EE) and testosterone acting as ECDs on the prostate of both male and female adult gerbils exposed to these agents during the embryonic phase. Consequently, pregnant gerbils were treated either with 10 μg/kg/day of EE or with a single dose of 1 mg of testosterone cypionate. The pups that were born 6-8 days after testosterone exposure and the pups that were born after 3 days of EE exposure were allowed to grow but were sacrificed within 4 months. Serological, morphological, stereological, and immunohistochemical analyses were used. Overall, the results showed that both sexes exposed to testosterone and EE during gestation had a prostatic gland with an increased stromal and epithelial and a reduced luminal compartment. Moreover, we observed that glands affected with prostatic intraepithelial neoplasia showed intense stromal reshuffling. In conclusion, although these alterations were observed in both sexes, more relevant to this study was the differential responsiveness of males and females exposed to these different drugs. Whereas the EE affected males more, the testosterone was more harmful to the females., (Copyright © 2012 Wiley Periodicals, Inc.)

Understanding the evolutionary mechanisms that promote and maintain cooperative behavior is recognized as a major theoretical problem where the intricacy increases with the complexity of the participating individuals. This is epitomized by the diverse nature of Human interactions, contexts, preferences and social structures. Here we discuss how social diversity, in several of its flavors, catalyzes cooperative behavior. From the diversity in the number of interactions an individual is involved to differences in the choice of role models and contributions, diversity is shown to significantly increase the chances of cooperation. Individual diversity leads to an overall population dynamics in which the underlying dilemma of cooperation is changed, benefiting the society as whole. In addition, we show how diversity in social contexts can arise from the individual capacity for organizing their social ties. As such, Human diversity, on a grand scale, may be instrumental in shaping us as the most sophisticated cooperative entities on this planet., (Copyright © 2011 Elsevier Ltd. All rights reserved.)

Often groups need to meet repeatedly before a decision is reached. Hence, most individual decisions will be contingent on decisions taken previously by others. In particular, the decision to cooperate or not will depend on one's own assessment of what constitutes a fair group outcome. Making use of a repeated N-person prisoner's dilemma, we show that reciprocation towards groups opens a window of opportunity for cooperation to thrive, leading populations to engage in dynamics involving both coordination and coexistence, and characterized by cycles of cooperation and defection. Furthermore, we show that this process leads to the emergence of fairness, whose level will depend on the dilemma at stake.

Recurrent early miscarriages (excluding chromosomal anomalies), late fetal loss, and maternal thrombosis are characteristic of obstetric antiphospholipid syndrome (APS). Obstetric complications such as preeclampsia, fetal growth restriction, premature delivery, and fetal death also occur in higher frequency in APS patients than in the general population. A high-risk obstetric center is needed for proper evaluation of and intervention with pregnant women with APS. Association with lupus carries additional risk of thrombosis when antiphospholipid antibodies (aPLs) are present. Gestational results with live births are improved to about 80% when antithrombotic therapy is used, but failure in 20% to 30% of the cases despite correct treatment with low-dose aspirin with or without heparin reveals new pathways for pregnancy loss in APS and unmet needs. At the moment, there is no recommendation to investigate patients with infertility for the presence of aPLs.

Social networks affect in such a fundamental way the dynamics of the population they support that the global, population-wide behavior that one observes often bears no relation to the individual processes it stems from. Up to now, linking the global networked dynamics to such individual mechanisms has remained elusive. Here we study the evolution of cooperation in networked populations and let individuals interact via a 2-person Prisoner's Dilemma--a characteristic defection dominant social dilemma of cooperation. We show how homogeneous networks transform a Prisoner's Dilemma into a population-wide evolutionary dynamics that promotes the coexistence between cooperators and defectors, while heterogeneous networks promote their coordination. To this end, we define a dynamic variable that allows us to track the self-organization of cooperators when co-evolving with defectors in networked populations. Using the same variable, we show how the global dynamics--and effective dilemma--co-evolves with the motifs of cooperators in the population, the overall emergence of cooperation depending sensitively on this co-evolution.

In a world in which the pace of cities is increasing, prompt access to relevant information is crucial to the understanding and regulation of land use and its evolution in time. In spite of this, characterization and regulation of urban areas remains a complex process, requiring expert human intervention, analysis and judgment. Here we carry out a spatio-temporal fractal analysis of a metropolitan area, based on which we develop a model which generates a cartographic representation and classification of built-up areas, identifying (and even predicting) those areas requiring the most proximate planning and regulation. Furthermore, we show how different types of urban areas identified by the model co-evolve with the city, requiring policy regulation to be flexible and adaptive, acting just in time. The algorithmic implementation of the model is applicable to any built-up area and simple enough to pave the way for the automatic classification of urban areas worldwide.

We investigated the effect of 96 h paradoxical sleep deprivation (PSD) and 21-day sleep restriction (SR) on prostate morphology using stereological assays in male rats. After euthanasia, the rat ventral prostate was removed, weighed, and prepared for conventional light microscopy. Microscopic analysis of the prostate reveals that morphology of this gland was altered after 96 h of PSD and 21 days of SR, with the most important alterations occurring in the epithelium and stroma in the course of both procedures compared with the control group. Both 96 h PSD and 21-day SR rats showed lower serum testosterone and higher corticosterone levels than control rats. The significance of our result referring to the sleep deprivation was responsible for deep morphological alterations in ventral prostate tissue, like to castration microscopic modifications. This result is due to the marked alterations in hormonal status caused by PSD and SR.

TIMPs in the prostates of male and female gerbils and evaluated the effects of testosterone on the expression of these enzymes. Ventral prostates from male gerbils that were either intact or had been castrated for 7 or 21 days, along with prostates from female gerbils that were either intact or had been treated with testosterone for 7 or 21 days, were submitted to histological, stereological and immunohistochemical analyses. Stereology of prostatic components showed significant alterations of tissue compartments in the ventral male prostate after castration, especially after 21 days, with a significant increase in stroma. Administration of testosterone led to disorganization in the female prostate, with a significant increase in collagen fibers and smooth muscle cells after 21 days, along with the development of epithelial lesions such as PINs. MMP-2 increased after 21 days of castration in males; however, the TIMP-2 immunoreaction for this group was weak or absent. In females, the expression of MMP-2 appeared to decrease after 7 days of treatment with testosterone, but after 21 days, both epithelium and stroma showed a stronger reaction for MMP-2 than the controls. The expression of TIMP-2 in the treated females was similar to its expression in the castrated males. We conclude that the distribution of MMPs and TIMPs in both male and female prostates is altered by androgen manipulation, but the mechanism of stromal regulation appears to be distinct between genders because both the lack of T in castrated males and the excess levels of T in treated females lead to the same effect.

In this work, it is shown that the quartz crystal microbalance (QCM) can be a powerful and simple tool for quick and precise kinetic enzymatic assays. This is shown by measuring immobilized acetylcholinesterase (AChE) activity with variations of pH as a case study., (Copyright © 2011 Elsevier Inc. All rights reserved.)

Cooperation is ubiquitous in the world surrounding us, from bacteria to Human interactions. In Humans, cooperation is often associated with various group decisions, resulting from their complex web of interrelated interests, associations or preferences. The existence of such social structures not only opens the opportunity of having diverse behaviors depending on the individuals' social position, but also for a dynamical allocation of contributions depending on the returns obtained from each group. Here, we address these issues by studying the evolution of cooperation under Public Goods Games in the framework of Evolutionary Game Theory where cooperative players are able to distribute their donations to their liking. As a result, cooperation is greatly enhanced when the community structure is described by homogeneous graphs, as cooperators become able to support cooperative groups and retaliate against those with poor achievements by withdrawing donations from them. Whenever the underlying network becomes complex enough to add diversity to the distribution of group sizes, directed investments do not optimize the emergence of cooperation, but they do enhance its robustness against the invasion of a minority of free-riders. We define a robustness index and show that directed investments expand the robustness of cooperation by about 50%., (Copyright © 2011 Elsevier Ltd. All rights reserved.)

The gerbil female prostate is located paraurethrally and has all the histological components of the male prostate, like secretor epithelium and fibromuscular stroma. This gland, like the prostate in males, is targeted by testosterone action, which promotes morphofunctional development. Furthermore, estrogens are required to maintain the male and female prostate and this gland presents both estrogen receptors (ER-α and ER-β). In the present work the structural and morphometric-stereological and serological aspects, as well as the quantification of the incidence, multiplicity and percentage of acini affected by different lesions were analyzed. Animals were divided into four groups: five adult nuliparous (AN) gerbils; five adult multiparous (AM) gerbils; five senescent nulliparous (SN) gerbils; five senescent multiparous (SM) gerbils, and were weighed and sacrificed by CO(2) inhalation. The ventral prostate was dissected out, weighed and fixed to perform histological and morphometric-stereological analysis and quantification of prostate disorders. A high rate of lesions, mainly dysplasia, was identified in tissue from senescent multiparous and adult multiparous animals. Prostatitis was found mainly in SN animals, while dysplasia, hyperplasia, neoplasia, PIA and adenocarcinoma were common in SM ones. Although the proliferative lesion incidence was high in AN group, it was highest in the SM group. The hormonal events which occur due to the estrous cycle in female gerbils (after and before each pregnancy) may be responsible for the high number of lesions observed in our study and all the data presented herein lead us to assume that pregnancy promotes augmentations in both the incidence and the multiplicity of proliferative disorders in the gerbil female prostate since progesterone levels remain high during pregnancy., (Copyright © 2011 Elsevier Ltd. All rights reserved.)

The gerbil female prostate undergoes morphological and physiological changes resulting from hormonal fluctuations that occur during the reproductive cycle. These repetitive cycles of glandular growth and regression are followed by an extensive reconstruction and remodeling of prostate stroma throughout the reproductive life of the female gerbil. The objective of this study was to evaluate the effect that the hormonal fluctuations of the reproductive cycle have on the stromal remodeling and the expression and activity of matrix metalloproteinases MMP-2 and -9 in the adult female gerbil prostate. For this, serological, ultrastructural, immunohistochemical and biochemical methods were employed. The results showed that the major stromal alteration coincide with the peak of estradiol, which occurs in estrus, and with the peak of progesterone, occurring during diestrus II. MMP-2 and -9 presented a similar pattern of expression and activity during estrous cycle. The estrus was the phase of greater expression and activity of MMP-2 and -9. On the other hand, in DI and DII, the tissue expression and activity of MMP-2 and -9 was very weak. These results are important since they suggest the involvement of estradiol and progesterone in regulating the expression and activity of MMP-2 and -9 in adult gerbil female prostate., (Copyright © 2011 Elsevier Inc. All rights reserved.)

In the present study Tradescantia pallida micronucleus (Trad-MCN) bioassay was used to assess the genotoxicity of particulate matter with a mass median aerodynamic diameter less than 10 μm (PM₁₀) in Tangara da Serra (MT), a Brazilian Amazon region that suffers the impact of biomass burning. The levels of PM (coarse and fine size fractions) and black carbon (BC) collected were also measured. Furthermore, the alkanes and polycyclic aromatic hydrocarbons (PAHs) were identified and quantified in the samples taken during the burning period by gas chromatography with flame ionization detection (GC-FID). The PM and BC results for both fractions indicate a strong correlation (p < 0.001). The analysis of alkanes indicates an anthropic influence. Retene was the most abundant PAH found, an indicator of biomass burning, and 12 other PAHs considered to be potentially mutagenic and/or carcinogenic were identified in this sample. The Trad-MCN bioassay showed a significant increase in micronucleus frequency during the period of most intense burning, possibly related to the mutagenic PAHs that were found in such extracts. This study demonstrated that Trad-MCN was sensitive and efficient in evaluating the genotoxicity of organic compounds from biomass burning. It further emphasizes the importance of performing chemical analysis, because changes in chemical composition generally have a negative effect on many living organisms. This bioassay (ex situ), using T. pallida with chemical analysis, is thus recommended for characterizing the genotoxicity of air pollution., (Crown Copyright © 2011. Published by Elsevier Inc. All rights reserved.)

From group hunting to global warming, how to deal with collective action may be formulated in terms of a public goods game of cooperation. In most cases, contributions depend on the risk of future losses. Here, we introduce an evolutionary dynamics approach to a broad class of cooperation problems in which attempting to minimize future losses turns the risk of failure into a central issue in individual decisions. We find that decisions within small groups under high risk and stringent requirements to success significantly raise the chances of coordinating actions and escaping the tragedy of the commons. We also offer insights on the scale at which public goods problems of cooperation are best solved. Instead of large-scale endeavors involving most of the population, which as we argue, may be counterproductive to achieve cooperation, the joint combination of local agreements within groups that are small compared with the population at risk is prone to significantly raise the probability of success. In addition, our model predicts that, if one takes into consideration that groups of different sizes are interwoven in complex networks of contacts, the chances for global coordination in an overall cooperating state are further enhanced.

Herpes simplex virus is an important human pathogen responsible for a range of diseases from mild uncomplicated mucocutaneous infections to life-threatening ones. Currently, the emergence of Herpes simplex virus resistant strains increased the need for more effective and less cytotoxic drugs for Herpes treatment. In this work, we synthesized a series of oxoquinoline derivatives and experimentally evaluated the antiviral activity against acyclovir resistant HSV-1 strain as well as their cytotoxity profile. The most active compound (3b), named here as Fluoroxaq-3b, showed a promising profile with a better cytotoxicity profile than acyclovir. The theoretical analysis of the structure-activity relationship of these compounds revealed some stereoelectronic properties such as lower LUMO energy and lipophilicity, besides a higher polar surface area and number of hydrogen bond acceptor groups as important parameters for the antiviral activity. Fluoroxaq-3b showed a good oral theoretical bioavailability, according to Lipinski rule of five, with a promising profile for further in vivo analysis.

Obstructive sleep apnea hypopnea syndrome (SAHS) is a complex disease of the upper respiratory airways. SAHS physiopathology is multifactorial in which airway compliance is a very important component. To evaluate the tissue changes in the palatopharyngeal muscle by morphometric, histochemical, immunohistochemical, and stereological quantification, with special attention to extracellular matrix associated with this muscle at the structural and ultrastructural levels. Thirty patients with SAHS were divided into groups of 10 according to disease severity: mild, moderate, and severe SAHS. In addition, the control group consisted of 10 patients. Fragments of palatopharyngeal muscle removed from patients with SAHS and tonsillectomies from patients in the control group were histopathologically submitted to light microscopy and transmission electron microscopy. Histopathological evaluations by light and transmission electron microscopes showed differences in analyzed groups, such as reduction of the muscle fiber diameter in patients with SAHS, taking disease severity into consideration. In contrast, stereological analysis showed a gradual increase of the collagen and elastic system fibers relative frequencies, proportionally to SAHS seriousness. MMP-2 and MMP-9 immunostaining also showed an increased reaction in the muscle fiber cytoplasm and endomisium during SAHS progression. The ultrastructural analysis showed that palatopharyngeal muscle fibers presented cytoplasmic residual corpuscles, a sign of early cell aging. In conclusion, the increase of tissue compliance in individuals with SAHS can be, in addition to other factors, consequence of diminished contractile activity of the muscle fibers, which exhibited clear signs of early senescence. Moreover, extracellular matrix components changes may contribute to muscle myopathy during SAHS progression., (Copyright © 2010 Wiley-Liss, Inc.)

A finite-population dynamic evolutionary model is presented, which shows that increasing the individual capacity of sending pre-play signals (without any pre-defined meaning), opens a route for cooperation. The population dynamics leads individuals to discriminate between different signals and react accordingly to the signals received. The proportion of time that the population spends in different states can be calculated analytically. We show that increasing the number of different signals benefits cooperative strategies, illustrating how cooperators may take profit from a diverse signaling portfolio to forecast future behaviors and avoid being cheated by defectors., (Copyright © 2011 Elsevier Ltd. All rights reserved.)

Cell therapy constitutes a possibility for improving nerve regeneration, increasing the success of nerve repair. We evaluate the use of mononuclear cells in the regeneration of the sciatic nerve after axotomy followed by end-to-end neurorrhaphy. Forty adult male Wistar rats (250-300 g) were divided into four groups: (1) sham, (2) neurorrhaphy: the sciatic nerve was sectioned and repaired using epineural sutures, (3) culture medium: after the suture, received an injection of 10 μL of culture medium into the nerve, and (4) mononuclear cell: after the suture, a concentration of 3 × 10(6) of mononuclear cell was injected in epineurium region. Mononuclear cells were obtained from the bone marrow aspirates and separated by Ficoll-Hypaque method. The histological analyses were performed at the 4th postoperative day. The sciatic functional index, histological, and morphometric analyzes were used to evaluate nerve regeneration at the 6th postoperative week. Six rats were used for immunohistochemical analysis on the 4th postoperative day. In the group 4, on the fourth day, the histological analysis demonstrated a more accelerated degenerative process and an increase of the neurotrophic factors was observed. In the 6th week, all the morphometric results of the group 4 were statistically better compared with groups 2 and 3. There was a statistically significant improvement in the sciatic functional index for group 4 compared with groups 2 and 3. Mononuclear cells stimulated nerve regeneration, most probably by speeding up the Wallerian degeneration process as well as stimulating the synthesis of neurotrophic factors., (Copyright © 2010 Wiley-Liss, Inc.)

Background: From the simplest living organisms to human societies, cooperation among individuals emerges as a paradox difficult to explain and describe mathematically, although very often observed in reality. Evolutionary game theory offers an excellent toolbar to investigate this issue. Spatial structure has been one of the first mechanisms promoting cooperation; however, alone it only opens a narrow window of viability., Methodology/principal Findings: Here we equip individuals with incipient cognitive abilities, and investigate the evolution of cooperation in a spatial world where retaliation, forgiveness, treason and mutualism may coexist, as individuals engage in Prisoner's Dilemma games. In the model, individuals are able to distinguish their partners and act towards them based on previous interactions. We show how the simplest level of cognition, alone, can lead to the emergence of cooperation., Conclusions/significance: Despite the incipient nature of the individuals' cognitive abilities, cooperation emerges for unprecedented values of the temptation to cheat, being also robust to invasion by cheaters, errors in decision making and inaccuracy of imitation, features akin to many species, including humans.

Objective: To evaluate whether the type of cola drink (regular or diet) could influence the wear of enamel subjected to erosion followed by brushing abrasion., Method and Materials: Ten volunteers wore intraoral devices that each had eight bovine enamel blocks divided into four groups: ER, erosion with regular cola; EAR, erosion with regular cola plus abrasion; EL, erosion with light cola; and EAL, erosion with light cola plus abrasion. Each day for 1 week, half of each device was immersed in regular cola for 5 minutes. Then, two blocks were brushed using a fluoridated toothpaste and electric toothbrush for 30 seconds four times daily. Immediately after, the other half of the device was subjected to the same procedure using a light cola. The pH, calcium, phosphorus, and fluoride concentrations of the colas were analyzed using standard procedures. Enamel alterations were measured by profilometry. Data were tested using two-way ANOVA and Bonferroni test (P<.05)., Results: Regarding chemical characteristics, light cola presented pH 3.0, 13.7 mg Ca/L, 15.5 mg P/L, and 0.31 mg F/L, while regular cola had pH 2.6, 32.1 mg Ca/L, 18.1 mg P/L, and 0.26 mg F/L. The light cola promoted less enamel loss (EL, 0.36 Μm; EAL, 0.39 Μm) than its regular counterpart (ER, 0.72 Μm; EAR, 0.95 Μm) for both conditions. There was not a significant difference (P>.05) between erosion and erosion plus abrasion for light cola. However, for regular cola, erosion plus abrasion resulted in higher enamel loss than erosion alone., Conclusion: The data suggest that light cola promoted less enamel wear even when erosion was followed by brushing abrasion.

Background: Heart failure (HF) is an important public health problem, of which main clinical symptoms are dyspnea and fatigue. Noninvasive ventilatory support has been used as adjuvant therapy in cardiac rehabilitation in order to improve the functional capacity of patients., Objective: To evaluate the functional capacity of patients with HF submitted to ventilatory support., Methods: We evaluated the sociodemographic information, as well as data on quality of life, blood pressure (BP), peripheral oxygen saturation (SpO2), dyspnea, lactate concentration before and after the 6-minute walk test (6MWT) and the distance walked by patients of both sexes with chronic heart failure (CHF), with left ventricular ejection fraction (LVEF) < 45.0% , randomized in two groups: control and CPAP (the group used CPAP - 10 cmH2O for 30 minutes)., Results: A total of 12 patients, of which 8 were males, with CHF functional class II and III (NYHA) participated in the study. The patients had mean LVEF of 35.3 ± 8.7 and mean age was 46.3 ± 10.3 years. When comparing the control group with the CPAP group at the end of the 6th minute, there was a significant difference between the groups regarding SpO2 values (, Control: 93.6 ± 1.5 % vs CPAP: 96.1±1.8%; p = 0.027), index of dyspnea (, Control: 13.1 ± 1.16 vs CPAP: 11 ± 0.8; p = 0.009), lactate concentration (, Control: 3.3 ± 0.7 mmol/l vs CPAP: 2.3 ± 0.5 mmol/l; p = 0.025) and distance walked at the 6MWT (CONTROL: 420.6 ± 73.8 m vs CPAP: 534 ± 89.91 m; p = 0.038)., Conclusion: The previous use of the CPAP had beneficial effects on SpO2, index of dyspnea, lactate concentration, double product and the distance walked at the 6MWT in patients with CHF when performing the 6MWT.

Unlabelled: The association between differentiated thyroid carcinoma (DTC) and chronic lymphocytic thyroiditis (CLT) has been reported in literature., Aim: To evaluate the incidence of this association and to determine whether the CLT may influence on the early initial staging of DTC when associated with other variable risks., Study Design: Historical (retrospective) cohort., Materials and Methods: Fifty two patients with DTC were evaluated from 1999 to 2009. They were divided into two groups. The first group had 35 patients with DTC without DLT; the second had 17 patients with CLT. Total thyroidectomy was the treatment chosen for all patients. Similarities shared in both groups such as age, gender, histological tumor type, tumor diameter, regional only or with distant metastases, extrathyroidal invasion, multifocality and presence of tumor capsule were considered. T-Student tests and Chi-square tests were applied to analyze the data., Results: The incidence of DTC without CLT was higher that of DTC+CLT (p = 0.0126). We noticed no statistic differences between the common variables analyzed., Conclusions: CLT occurred in 33% of the patients with DCT. All cases of DTC were in the early stages.

Background: Androgenic obesity is associated with a higher risk of metabolic disorders, thus favoring the occurrence of cardiovascular diseases and other morbidities., Objective: To verify the influence of the visceral adipose tissue (VAT) area, measured by computed tomography (CT), on the metabolic alterations in adult and elderly individuals., Methods: CT results and lipoprotein levels, total cholesterol and fractions, triglycerides, glycemia and uric acid levels, were obtained from 194 individuals stratified by sex, age group and body mass and analyzed using the tests of correlation and means., Results: The elderly individuals presented higher VAT area, glycemia, uric acid and total cholesterol levels. The most important correlations were observed between VAT area, triglycerides (TG) and VLDL-c (r > 0.5; p < 0.01), in both age groups. The mean VAT area was always higher when TG and glycemia levels were altered, in both age groups., Conclusion: Most tests showed a strong correlation with VAT area, which was considered as risk for metabolic alterations. In elderly individuals, the risk VAT area seems to be higher than that of adult individuals.

The female prostate (Skene's paraurethral gland) in the rat is morphologically similar to the ventral lobe of male adults and has been described in other rodent species and humans. Previous studies on prostate morphogenesis suggest that female Wistar rats (Rattus norvegicus) do not develop this gland due to the absence of testosterone during the embryonic and neonatal periods. On the other hand, studies conducted in our laboratory have shown that some females of this species can present an undeveloped but functional prostate. Recent studies on this gland have caused scientific interest because, besides being active in the processes of synthesis and secretion of prostatic material, it is also targeted by both malignant and benign lesions, mainly during senescence. Thus, this work aims to evaluate the structure of female prostate of adult rats (Rattus norvegicus) under normal conditions and under the effect of testosterone treatment and carry out comparative studies on the ventral prostate of young and adult male rats. Morphological and morphometric stereological analyses and immunocytochemical and ultrastructural studies were conducted. The results have shown that the prostate gland of rats exposed to androgen therapy have experienced intense growth, becoming more active in relation to synthesis and secretion. It may be concluded that the prostate in control adult female rats is morphologically very similar to the prostatic ventral lobe of young male rats. Besides, under androgenic action, the female prostate grows considerably and becomes similar to the prostatic ventral lobe in male adults., (Copyright © 2010 Wiley-Liss, Inc.)

This study was conducted at three sites of different characteristics in São Paulo State: São Paulo (SPA), Piracicaba (PRB) and Mata Atlântica Forest (MAT). PM(10), n-alkanes, pristane and phytane, PAHs, water-soluble ions and biomass burning tracers like levoglucosan and retene, were determined in quartz fiber filters. Samplings occurred on May 8th to August 8th, 2007 at the MAT site; on August 15th to 29th in 2007 and November 10th to 29th in 2008 at the PRB site and, March 13th to April 4th in 2007 and August 7th to 29th in 2008 at the SPA site. Aliphatic compounds emitted biogenically were less abundant at the urban sites than at the forest site, and its distribution showed the influence of tropical vascular plants. Air mass transport from biomass burning regions is likely to impact the sites with specific molecular markers. The concentrations of all species were variable and dependent of seasonal changes. In the most dry and polluted seasons, n-alkane and cation total concentrations were similar between the megacity and the biomass burning site. PAHs and inorganic ion abundances were higher at São Paulo than Piracicaba, yet, the site influenced by biomass burning seems to be the most impacted by the organic anion abundance in the atmosphere. Pristane and phytane confirm the contamination by petroleum residues at urban sites; at the MAT site, biological activity and long range transport of pollutants might influence the levels of pristane., (Copyright © 2010 Elsevier B.V. All rights reserved.)

The present study examined the response of the prostate epithelium of senescent gerbils submitted to orchiectomy and with or without steroidal blockade. Animals were divided into five groups, all surgically castrated except the control group composed of intact animals. In the experimental groups, doses of flutamide and/or tamoxifen were applied for 1, 3, 7 and 30 days postcastration. The structural methods applied reveal that castration, whether associated or not with anti-steroidal drugs, promoted short- and long-term decrease in wet and relative weights of the prostate. The quantitative decline of epithelial compartment proportion observed at the end of treatment was due to the sum of slight changes in the epithelium and lumen. The apoptotic index had risen significantly at 1 day and declined at 7 days postcastration. Androgen receptor (AR) expression decreased after 3 days of hormonal ablation, coinciding with the highest levels of apoptosis and cell proliferation observed in all treated groups. The majority of cells remained differentiated in all groups due to CK 8/18 expression. Some animals remained with injuries such as carcinomas and adenocarcinomas after hormonal ablation. In the latter a mixture of AR-positive and AR-negative cells was identified. Microinvasive carcinomas found in the group treated for 30 days consisted of PCNA-positive, inflammatory and non-proliferating cells. Low apoptosis incidence and bcl-2 positive cells were observed in these lesions. The treatments promoted a reduction of lesions in older gerbils, but treatment-resistant tumours will improve understanding of the events that lead to hormone resistance., (© 2010 The Authors. Journal compilation © 2010 Blackwell Publishing Ltd.)

Human societies are organized in complex webs that are constantly reshaped by a social dynamic which is influenced by the information individuals have about others. Similarly, epidemic spreading may be affected by local information that makes individuals aware of the health status of their social contacts, allowing them to avoid contact with those infected and to remain in touch with the healthy. Here we study disease dynamics in finite populations in which infection occurs along the links of a dynamical contact network whose reshaping may be biased based on each individual's health status. We adopt some of the most widely used epidemiological models, investigating the impact of the reshaping of the contact network on the disease dynamics. We derive analytical results in the limit where network reshaping occurs much faster than disease spreading and demonstrate numerically that this limit extends to a much wider range of time scales than one might anticipate. Specifically, we show that from a population-level description, disease propagation in a quickly adapting network can be formulated equivalently as disease spreading on a well-mixed population but with a rescaled infectiousness. We find that for all models studied here--SI, SIS and SIR--the effective infectiousness of a disease depends on the population size, the number of infected in the population, and the capacity of healthy individuals to sever contacts with the infected. Importantly, we indicate how the use of available information hinders disease progression, either by reducing the average time required to eradicate a disease (in case recovery is possible), or by increasing the average time needed for a disease to spread to the entire population (in case recovery or immunity is impossible).

The female organs, which are regulated by steroid hormones, are targets of studies especially those related to senescence. However, although the female prostate is an organ influenced by hormones and susceptible to lesions, there is still little information about its histopathology. Thus, given the morphophysiological similarity between the prostate in women and female gerbils, the present study aimed to identify the spontaneous histopathological changes in this rodent to provide contributions to the understanding of lesions that also affect the human female prostate. The structural, ultrastructural, immunohistochemical, morphometric-stereological and serological aspects, as well as the quantification of the incidence, multiplicity and percentage of acini affected by different lesions were analyzed. Benign prostate lesions including hyperplasia, prostatitis, microcalculi and calculi; preneoplastic lesions like dysplasias; premalignant lesions, such as high grade prostatic intraepithelial neoplasia as well as malignant ones, specifically adenocarcinoma, were identified in the adult gland, but they were intensified during senescence, which is possibly due to the imbalance among steroid hormone levels. Although clinical attention focuses on other urogenital organs, the real condition of the histopathological injuries in the human female prostate should be considered. A serious preventive work regarding the female prostate could be applied in the gynaecological context in order to monitor the gland and avoid possible disturbances to women's health and consequently provide better quality of life.

Purpose: The purpose of this study was to evaluate the effects of caffeine ingestion before a resistance exercise session on markers of muscle damage (CK, LDH, ALT, AST) and leukocyte levels., Methods: Fifteen soccer athletes completed two resistance exercise sessions that differed only in the ingestion of caffeine or a placebo preworkout., Results: CK concentration increased significantly following the caffeine session (415.8+/-62.8 to 542.0+/-73.5) and the placebo session (411.5+/-43.3 to 545.8+/-59.9), with no significant differences between sessions. Similarly, LDH concentration increased significantly following the caffeine session (377.5+/-18.0 to 580.5+/-36.1) and the placebo session (384.8+/-13.9 to 570.4+/-36.1), with no significant differences between sessions. Both sessions resulted in significant increases in the total leukocyte count (caffeine=6.24+/-2.08 to 8.84+/-3.41; placebo=6.36+/-2.34 to 8.77+/-3.20), neutrophils (caffeine=3.37+/-0.13 to 5.15+/-0.28; placebo=3.46+/-0.17 to 5.12+/-0.24), lymphocytes (caffeine=2.19+/-0.091 to 2.78+/-0.10; placebo=2.17+/-0.100 to 2.75+/-0.11), and monocytes (caffeine=0.53+/-0.02 to 0.72+/-0.06; placebo=0.56+/-0.03 to 0.69+/-0.04), with no significant differences between sessions., Conclusion: Ingestion of caffeine at 4.5 mg/kg(-1) did not augment markers of muscle damage or leukocyte levels above that which occurs through resistance exercise alone.

Objective: The rapid differentiation between Mycobacterium tuberculosis and nontuberculous mycobacteria is fundamental for patients co-infected with tuberculosis and HIV. To that end, we use two methods in our laboratory: detection of cord factor and PCR-restriction enzyme analysis (PRA). The objective of this study was to evaluate the accuracy of a screening test on solid medium as a rapid method for the presumptive identification of M. tuberculosis complex, considering costs and turnover time., Methods: A total of 152 strains were submitted to a combined screening test, consisting of the detection of cord factor under microscopy (Ziehl-Neelsen staining) and evaluation of the macroscopic aspect of colonies, as well as to PRA, which was used as the gold standard. Costs were estimated by calculating the price of all of the materials needed for each test., Results: The overall accuracy of cord factor detection alone was 95.4% (95% CI: 90.7-98.1%), and that of the combined screening test was 99.3% (95% CI: 96.4-100%). Cord factor detection costs US$ 0.25, whereas the PRA costs US$ 7.00. Results from cord factor detection are ready in 2 days, whereas PRA requires 4 days to yield results., Conclusions: The presumptive identification of M. tuberculosis using the macroscopic evaluation of colonies combined with cord factor detection under microscopy is a simple, rapid and inexpensive test. We recommend the combined screening test to rapidly identify M. tuberculosis in resource-poor settings and in less well-equipped laboratories while awaiting a definite identification by molecular or biochemical methods.

The evolution of cooperation described in terms of simple two-person interactions has received considerable attention in recent years, where several key results were obtained. Among those, it is now well established that the web of social interaction networks promotes the emergence of cooperation when modeled in terms of symmetric two-person games. Up until now, however, the impacts of the heterogeneity of social interactions into the emergence of cooperation have not been fully explored, as other aspects remain to be investigated. Here we carry out a study employing the simplest example of a prisoner's dilemma game in which the benefits collected by the participants may be proportional to the costs expended. We show that the heterogeneous nature of the social network naturally induces a symmetry breaking of the game, as contributions made by cooperators may become contingent on the social context in which the individual is embedded. A new, numerical, mean-field analysis reveals that prisoner's dilemmas on networks no longer constitute a defector dominance dilemma--instead, individuals engage effectively in a general coordination game. We find that the symmetry breaking induced by population structure profoundly affects the evolutionary dynamics of cooperation, dramatically enhancing the feasibility of cooperators: cooperation blooms when each cooperator contributes the same cost, equally shared among the plethora of games in which she participates. This work provides clear evidence that, while individual rational reasoning may hinder cooperative actions, the intricate nature of social interactions may effectively transform a local dilemma of cooperation into a global coordination problem.

In the animal world, performing a given task which is beneficial to an entire group requires the cooperation of several individuals of that group who often share the workload required to perform the task. The mathematical framework to study the dynamics of collective action is game theory. Here we study the evolutionary dynamics of cooperators and defectors in a population in which groups of individuals engage in N-person, non-excludable public goods games. We explore an N-person generalization of the well-known two-person snowdrift game. We discuss both the case of infinite and finite populations, taking explicitly into consideration the possible existence of a threshold above which collective action is materialized. Whereas in infinite populations, an N-person snowdrift game (NSG) leads to a stable coexistence between cooperators and defectors, the introduction of a threshold leads to the appearance of a new interior fixed point associated with a coordination threshold. The fingerprints of the stable and unstable interior fixed points still affect the evolutionary dynamics in finite populations, despite evolution leading the population inexorably to a monomorphic end-state. However, when the group size and population size become comparable, we find that spite sets in, rendering cooperation unfeasible.