RESUMO
It has been postulated that schizophrenia (SZ) is related to a lower expression of brain-derived neurotrophic factor (BDNF). In the past few years, an increasing number of divergent clinical studies assessing BDNF in serum and plasma have been published. It is now possible to verify the relationship between BDNF levels and severity of symptoms in SZ as well as the effects of antipsychotic drugs on BDNF using meta-analysis. The aims of this study were to verify if peripheral BDNF is decreased in SZ, whether its levels are correlated with positive and negative symptomatology and if BDNF levels change after antipsychotic treatment. This report consists of two distinct meta-analyses of peripheral BDNF in SZ including a total of 41 studies and more than 7000 participants: (1) peripheral BDNF levels in serum and plasma were moderately reduced in SZ compared with controls. Notably, this decrease was accentuated with the disease duration. However, the extent of peripheral BDNF level decrease did not correlate with the severity of positive and negative symptoms. (2) In plasma, but not serum, peripheral BDNF levels are consistently increased after antipsychotic treatment irrespective of the patient's response to medication. In conclusion, there is compelling evidence that there are decreased levels of peripheral BDNF in SZ, in parallel to previously described reduced cerebral BDNF expression. It remains unclear whether these systemic changes are causally related to the development of SZ or if they are merely a pathologic epiphenomenon.
Assuntos
Antipsicóticos/uso terapêutico , Fator Neurotrófico Derivado do Encéfalo/sangue , Esquizofrenia/sangue , Esquizofrenia/tratamento farmacológico , Adulto , Biomarcadores/sangue , Estudos de Casos e Controles , Feminino , Humanos , Masculino , Pessoa de Meia-Idade , Adulto JovemRESUMO
The time evolution of the one-particle distribution function of an N-particle classical Hamiltonian system with long-range interactions satisfies the Vlasov equation in the limit of infinite N. In this paper we present a new derivation of this result using a different approach allowing a discussion of the role of interparticle correlations on the system dynamics. Otherwise for finite N collisional corrections must be introduced. This has allowed a quite comprehensive study of the quasistationary states (QSSs) though many aspects of the physical interpretations of these states still remain unclear. In this paper a proper definition of time scale for long time evolution is discussed, and several numerical results are presented for different values of N. Previous reports indicate that the lifetimes of the QSS scale as N1.7 or even the system properties scale with exp(N). However, preliminary results presented here indicates that time scale goes as N2 for a different type of initial condition. We also discuss how the form of the interparticle potential determines the convergence of the N-particle dynamics to the Vlasov equation. The results are obtained in the context of the following models: the Hamiltonian mean field, the Self-gravitating ring model, and one- and two-dimensional systems of gravitating particles. We have also provided information of the validity of the Vlasov equation for finite N.
RESUMO
In order to compare the effectiveness of birds and insects as pollinators, we studied the floral biology of the bromeliad Aechmea nudicaulis (L.) Grisebach in the biome of the Atlantic rain forest, southern Brazil. On Santa Catarina Island, flowering extends from mid-September to the end of December, with diurnal anthesis. The reproductive system is obligatory xenogamy, thus pollinator-dependent. Flowers secrete 31.84 µl of nectar per day, with a mean sugar concentration of 23.2%. Highest nectar volume and sugar concentration occur at the beginning of anthesis. Most floral traits are characteristic for ornithophily, and nectar production appears to be adapted to the energy demand of hummingbirds. Continued secretion of the sucrose-dominated nectar attracts and binds visitors to inflorescences, strengthening trapline foraging behaviour. Experiments assessing seed set after single flower visits were performed with the most frequent visitors, revealing the hummingbird Thalurania glaucopis as the most effective pollen vector. In addition, bees are also functional pollinators, as substantiated by their high visitation frequency. We conclude that this pollination system is bimodal. Thus, there is redundancy in the pollination service provided by birds and bees, granting a high probability of successful reproduction in Ae. nudicaulis.
Assuntos
Abelhas , Aves , Bromeliaceae/fisiologia , Flores/fisiologia , Polinização/fisiologia , Animais , Brasil , Bromeliaceae/anatomia & histologia , Flores/anatomia & histologia , Frutose/análise , Glucose/análise , Insetos , Néctar de Plantas/química , Pólen , Reprodução , Sacarose/análiseRESUMO
In order to analyze the pollen resources used by the orchid bee Euglossa annectans, samples of larval provisions from cells under construction were taken from 12 different trap nests (wooden boxes) on Santa Catarina Island, southern Brazil. The 43 samples collected between 2002 and 2005 represented all months except December. Overall, 74 pollen types from 24 families were distinguished. Among the 26 pollen types that reached more than 10% in monthly means, the families Melastomataceae, Bromeliaceae, Ochnaceae, Fabaceae, and Myrtaceae were most frequently represented. The Shannon-Weaver diversity index H' for the 43 brood cells varied from 0.10-1.65 and the annual diversity was 0.98. Similarity indices ranged from 0 to 0.87 and were highest during spring and summer. The results characterize E. annectans as a polylectic species. Based on these data, we can conclude that Euglossa females may act as pollinators of many forest species.
Assuntos
Abelhas , Orchidaceae , Pólen , Animais , Estações do AnoRESUMO
NAPc2, an anticoagulant protein from the hematophagous nematode Ancylostoma caninum evaluated in phase-II/IIa clinical trials, inhibits the extrinsic blood coagulation pathway by a two step mechanism, initially interacting with the hitherto uncharacterized factor Xa exosite involved in macromolecular recognition and subsequently inhibiting factor VIIa (K(i)=8.4 pM) of the factor VIIa/tissue factor complex. NAPc2 is highly flexible, becoming partially ordered and undergoing significant structural changes in the C terminus upon binding to the factor Xa exosite. In the crystal structure of the ternary factor Xa/NAPc2/selectide complex, the binding interface consists of an intermolecular antiparallel beta-sheet formed by the segment of the polypeptide chain consisting of residues 74-80 of NAPc2 with the residues 86-93 of factor Xa that is additional maintained by contacts between the short helical segment (residues 67-73) and a turn (residues 26-29) of NAPc2 with the short C-terminal helix of factor Xa (residues 233-243). This exosite is physiologically highly relevant for the recognition and inhibition of factor X/Xa by macromolecular substrates and provides a structural motif for the development of a new class of inhibitors for the treatment of deep vein thrombosis and angioplasty.
Assuntos
Ancylostoma/química , Fator Xa/química , Proteínas de Helminto/química , Animais , Anticoagulantes/farmacologia , Sítios de Ligação , Bovinos , Fator VIIa/química , Fator VIIa/metabolismo , Fator Xa/metabolismo , Humanos , Modelos Moleculares , Dados de Sequência Molecular , Ligação Proteica , Estrutura Terciária de Proteína , Relação Estrutura-Atividade , Tromboplastina/química , Tromboplastina/metabolismoRESUMO
OBJECTIVE: To examine effectiveness of immunization recall in an urban pediatric teaching clinic and to identify barriers to recall effectiveness. DESIGN: Randomized, controlled trial. Children aged 5 to 17 months who were not up to date (UTD) with recommended immunizations were identified and assigned to intervention (n = 294) or control groups (n = 309). The intervention consisted of a mailed postcard and up to 4 telephone calls. Two months after intervention, UTD status, visit, and probable missed opportunity rates were assessed. RESULTS: Of the intervention group, 30% could not be reached. In 12-month-old children in the intervention group compared with those in the control group, there was a trend toward higher UTD rates (51% vs 39%, P =.07) and a higher proportion of UTD children receiving immunizations as opposed to getting more complete documentation (25% vs 10%, P =.005). Similar differences between intervention and control children were not seen in the 7-month and 19-month age categories. More children in the intervention group had a health maintenance visit (17% vs 11%, P =.03). Of children in the intervention group who were seen when not UTD, 17 of 24 (71%) of those seen for an illness visit and 5 of 24 (21%) of those seen for health maintenance probably had missed opportunities to be immunized. CONCLUSIONS: Recall efforts were partially successful but were undermined by inability to reach the clinic population, poor documentation of immunizations, and missed opportunities.
Assuntos
Serviços de Saúde da Criança , Sistemas de Alerta , Colorado , Feminino , Hospitais de Ensino , Humanos , Lactente , Masculino , Estudos Prospectivos , População UrbanaRESUMO
Penicillium purpurogenum produces several enzymes active in xylan hydrolysis, of there, the acetyl xylan esterase (AXE) activity secreted by the fungus has now been studied. The amount of activity obtained in the culture is related to the degree of acetylation of the carbon source used, the best being chemically acetylated xylan. AXE was concentrated from culture supernatants by ultrafiltration and (NH4)2SO4 precipitation and fractionated by gel filtration in Bio-Gel P-300. Two peaks of activity (AXE I and AXE II) were obtained. These two enzymes were further purified separately to homogeneity by chromatography in CM-Sephadex C-50 and chromatofocusing. AXE I (M(r) 48,000) has a pl of 7.5, while AXE II (M(r) 23,000) has a pl of 7.8. Optimal enzyme activity was at pH 5.3 and 50 degrees C for AXE I and pH 6.0 and 60 degrees C for AXE II. Both enzymes are active towards several acetylated substrates. Antisera against the two enzymes do not cross-react, and the N-terminal sequences of AXE I and II do not show similarities. These results suggest that AXE I and AXE II are the products of different genes.
Assuntos
Acetilesterase/isolamento & purificação , Penicillium/enzimologia , Acetilesterase/genética , Acetilesterase/metabolismo , Sequência de Aminoácidos , Biotecnologia , Genes Fúngicos , Concentração de Íons de Hidrogênio , Imunoquímica , Ponto Isoelétrico , Dados de Sequência Molecular , Peso Molecular , Penicillium/genética , Homologia de Sequência de Aminoácidos , Especificidade por Substrato , TemperaturaRESUMO
The incidence of digoxin toxicity among patients in hospitals has declined in recent years. To evaluate whether a similar decline has occurred in ambulatory care, we reviewed randomly selected medical records for 183 outpatients receiving ongoing treatment with digoxin at 10 urban and rural Department of Veterans Affairs Medical Centers in the Rocky Mountain region. The prevalence of traditional risk factors for digoxin toxicity--elevated serum digoxin and serum creatinine levels, hypokalemia, and a new prescription of an interacting drug-was established from computerized laboratory and pharmacy records. Of the 183 patients, 50 (27.3%) had one or more risk factors for digoxin toxicity: serum digoxin levels were elevated in 13.6% of patients in whom a level was obtained, with hypokalemia in 14.3%, elevated creatinine levels in 17.9%, and possible drug interactions in 5.5% of patients over a 1-year period. Nevertheless, digoxin toxicity occurred in only 2 persons (1.1% or 1.4 per 100 patient-years of treatment). We conclude that digoxin toxicity was rare in this group of outpatients, even in persons presumed to be at high risk because of metabolic abnormalities, increased digoxin concentrations, or the use of interacting drugs. The low rate of digoxin toxicity in outpatients parallels the decline in the incidence of toxicity observed in hospital-based studies.