The cell surface of Trypanosoma cruzi: a fracture-flip, replica-staining label-fracture survey

Fracture-flip and replica-staining label-fracture were used to study the nanoanatomy and topochemistry of the cell surface of Trypanosoma cruzi. Fracture-flip surface images differentiate the three main developmental stages of T. cruzi. Epimastigotes display a smooth surface, except the cytostome which appears as a clearly demarcated, raised, roughly textured platform. Amastigotes and trypomastigotes are covered by numerous surface particles with diameters ranging from 10 to 20 nm and 15 to 30 nm, respectively. Labeling of concanavalin A receptors showed that the surfaces of amastigotes and trypomastigotes were labeled, with amastigotes displaying the highest density of gold particles. In contrast, epimastigotes were sparsely labeled with exception of the cytostome, where a higher density of labeling coincided with the raised platform seen in fracture-flipped specimens, and with the particle-free area exposed on fracture faces. Labeling of epimastigotes by Ricinus communis I and Wistaria floribunda lectins showed that surface receptors for these lectins were absent from the cytostome.     

Characterization of reactions of antimoniate and meglumine antimoniate with a guanine ribonucleoside at different pH

It has been shown previously that Sb^V forms mono- and bis-adducts with adenine and guanine ribonucleosides, suggesting that ribonucleosides may be a target for pentavalent antimonial drugs in the treatment of leishmaniasis. In the present work, the reactions of antimoniate (KSb(OH)₆) and meglumine antimoniate (MA) with guanosine 5′-monophosphate (GMP) have been characterized at 37 °C in aqueous solution and two different pH (5 and 6.5), using ESI(−)-MS and ¹H NMR. Acid and base species for both 1:1 and 1:2 Sb^V–GMP complexes were identified by ESI(−)-MS. The ¹H NMR anomeric region was explored for determining the concentrations of mono- and bis-adducts. This allows for the determination of stability constants for these complexes (5900 L mol⁻¹ for 1:1 complex and 370 L mol⁻¹ for 1:2 complex, at pD 5 and 37 °C). Kinetic studies at different pH indicated that formation and dissociation of both 1:1 and 1:2 Sb–GMP complexes are slow processes and favored at acidic pH (2150 L mol⁻¹ h⁻¹ for the rate constant of 1:1 complex formation and 0.25 h⁻¹ for the rate constant of 1:1 complex dissociation, at pD 5 and 37 °C). When MA was used, instead of antimoniate, formation of 1:1 Sb–GMP complex occurred, but with a slower rate constant. Assuming that MA consists essentially of a 1:1 Sb–meglumine complex, a stability constant for MA could also be estimated (8600 L mol⁻¹ at pD 5 and 37 °C). Thermodynamic and kinetic data are consistent with the formation of 1:1 Sb–ribonucleoside complexes in vertebrate hosts, following treatment with pentavalent antimonial drugs.     

Proteomic analysis of human mesenchymal stromal cells derived from adipose tissue undergoing osteoblast differentiation

Background aimsStem cells derived from human adipose tissue (ASC) have the capacity for renewal, are easily obtained and have plasticity properties that allow them to differentiate into several cell types, including osteoblast cells. With the aim of understanding the issue of the osteogenic process and finding reliable biomarkers in cells undergoing the osteogeneic differentiation process, this work took advantage of a proteomic approach to identify proteins involved in osteogenesis.MethodsFor this purpose, ASC were analyzed under three conditions: S0, in the absence of stimulation; S1, with 2 weeks of osteogenic medium stimulation; and S2, with 4 weeks of osteogenic medium stimulation. The identification of ASC was carried out by flow cytometry using antibodies specific to known undifferentiated stem cell-surface markers. Cell viability, enzymatic activity, mineral deposition, collagen structure and production and gene analyzes were evaluated for each condition.ResultsPhenotypic modifications were observed during the in vitro osteogenic differentiation process by two-dimensional (2-D) differential image gel electrophoresis (DIGE). The proteins were identified by mass espectrometry in tandem (MS/MS) analyzes using Matrix-assisted laser desorption/ionization with TOF/TOF is a tandem mass spectrometry method where two time-of-flight mass spectrometers are used consecutively (MALDI-TOF/TOF). A total of 51 differentially expressed proteins was identified when comparing the three observed conditions. Sixteen different spots were identified in the S0 stage compared with S2, while 28 different spots were found in S2 compared with S0. S1 expressed seven different spots compared with S0 and S2.ConclusionsThese findings suggest the involvement of several proteins directly related to the osteogenic pathway, which can be used to improve understanding of the osteogenic process.     

INCITE: A randomised trial comparing constraint induced movement therapy and bimanual training in children with congenital hemiplegia

Background  

Congenital hemiplegia is the most common form of cerebral palsy (CP) accounting for 1 in 1300 live births. These children have limitations in capacity to use the impaired upper limb and bimanual coordination deficits which impact on daily activities and participation in home, school and community life. There are currently two diverse intensive therapy approaches. Traditional therapy has adopted a bimanual approach (BIM training) and recently, constraint induced movement therapy (CIMT) has emerged as a promising unimanual approach. Uncertainty remains about the efficacy of these interventions and characteristics of best responders. This study aims to compare the efficacy of CIMT to BIM training to improve outcomes across the ICF for school children with congenital hemiplegia.     

Gibberellin biosynthesis and the regulation of plant development

Gibberellins (GAs) form a large family of plant growth substances with distinct functions during the whole life cycle of higher plants. The rate of GA biosynthesis and catabolism determines how the GA hormone pool occurs in plants in a tissue and developmentally regulated manner. With the availability of genes coding for GA biosynthetic enzymes, our understanding has improved dramatically of how GA plant hormones regulate and integrate a wide range of growth and developmental processes. This review focuses on two plant systems, pumpkin and Arabidopsis, which have added significantly to our understanding of GA biosynthesis and its regulation. In addition, we present models for regulation of GA biosynthesis in transgenic plants, and discuss their suitability for altering plant growth and development.     

Diphtheria-neutralizing antibody levels in healthy adults from Rio de Janeiro, Brazil

In Brazil, until 2004, the immunization policy against diphtheria involved childhood vaccination with no official routine booster dose administered after 15 years of age. This study assessed functional antibody levels against diphtheria among blood donors. A total of 140 blood samples were collected, and diphtheria antitoxin levels were evaluated by Vero cell neutralization test. The mean age of the population was 34 years old (range: 18-61 years); 37.8% females and 62.2% males. Overall, 30.7% (95%, CI: 23.4-38.7) individuals presented neutralizing antitoxin antibody titers < 0.01 IU/ml; 42.1% (95%, CI: 34.1-50.4) showed values between 0.01-0.09 IU/ml and, 27.1% (95%, CI: 20.2-34.9) had (3) 0.1 IU/ml. In the subgroup of individuals with history of diphtheria immunization during childhood (85%), a number of 28.5% showed unprotective levels of circulating neutralizing antibody (< 0.01 IU/ml). Despite the continuous progress of immunization programs directed to Brazilian population, currently healthy adults remain susceptible to diphtheria.     

Isolation and biochemical characterization of peptides presenting antimicrobial activity from the skin of Phyllomedusa hypochondrialis

Amphibian antimicrobial peptides have been known for many decades and several of them have been isolated from anuran species. Dermaseptins are among the most studied antimicrobial peptides and are found in the skin secretion of tree frogs from the Phyllomedusinae subfamily. These peptides exert a lytic action on bacteria, protozoa, yeast, and filamentous fungi at micromolar concentrations, but unlike polylysines, present little hemolytic activity. In this work, two antimicrobial peptides were isolated from the crude skin secretion of Phyllomedusa hypochondrialis and tested against Gram-positive and Gram-negative bacteria, presenting no hemolytic activity at the tested concentrations. One of them was identified with the recently reported peptide PS-7 belonging to the phylloseptin family, and another was a novel peptide, named DPh-1, which was fully purified, sequenced by ‘de novo’ mass spectrometry and grouped into Dermaseptins (DPh-1).     

Hemorphin and hemorphin-like peptides isolated from dog pancreas and sheep brain are able to potentiate bradykinin activity in vivo

Hemorphins are biologically active peptides, derived from hemoglobin, which presents a number of physiological activities. Proteolytic generation of these peptides is not fully understood; however, among their roles, is to provoke reduction on blood pressure. In this work, this particular biological effect was chosen as the monitor for the selection of mammalian vasoactive peptides. By combining high-performance liquid chromatography and mass spectrometry, including 'de novo' sequencing, several hemorphin-like peptides were identified presenting bradykinin potentiating activity. Moreover, taking LVV-hemorphin-7 as model compound, we evaluated its biological effect on blood pressure of anaesthetized rats. By summarizing all the results, it is possible to present the hemorphins as a family of proteolytically generated peptides that are able to potentiate bradykinin activity in vivo.     

Orpotrin: a novel vasoconstrictor peptide from the venom of the Brazilian stingray Potamotrygon gr. orbignyi

Characterization of the peptide content of venoms has a number of potential benefits for basic research, clinical diagnosis, development of new therapeutic agents, and production of antiserum. In order to analyze in detail the peptides and small proteins of crude samples, techniques such as chromatography and mass spectrometry have been employed. The present study describes the isolation, biochemical characterization, and sequence determination of a novel peptide, named Orpotrin from the venom of Potamotrygon gr. orbignyi. The natural peptide was shown to be effective in microcirculatory environment causing a strong vasoconstriction. The peptide was fully sequenced by de novo amino acid sequencing with mass spectrometry and identified as the novel peptide. Its amino acid sequence, HGGYKPTDK, aligns only with creatine kinase residues 97–105, but has no similarity to any bioactive peptide. Therefore, possible production of this peptide from creatine kinase by limited proteolysis is discussed. Taken together, the results indicate the usefulness of this single-step approach for low molecular mass compounds in complex samples such as venoms.