ATRIBUTOS FÍSICOS DO SOLO E DESENVOLVIMENTO DO ALGODOEIRO EM SEMEADURA DIRETA

O trabalho objetivou avaliar o efeito da utilização de plantas de cobertura em semeadura direta e da aplicação de nitrogênio em pré-semeadura do algodoeiro, nas alterações dos atributos físicos do solo e desenvolvimento de plantas do algodoeiro. O delineamento experimental empregado foi o de blocos ao acaso, disposto em faixas, compostos por: três plantas de cobertura (nabo forrageiro, aveia preta e aveia branca) implantadas no período do inverno; quatro doses de nitrogênio (0, 30, 60, e 90 kg ha-1 de N). Foram determinadas a resistência do solo à penetração, umidade gravimétrica, altura e número de nós das plantas de algodoeiro. O uso de aveia preta proporcionou aumento da umidade superficial do solo enquanto que o nabo forrageiro proporcionou aumento da umidade em profundidade. A utilização de culturas de cobertura não alterou a resistência do solo à penetração. A utilização de doses crescentes de nitrogênio em pre-semeadura do algodoeiro proporcionou aumento em altura e do número de nós por planta.

Resveratrol and its metabolites bind to PPARs

Resveratrol, a modulator of several signaling proteins, can exert off-target effects involving the peroxisome proliferator-activated receptor (PPAR) transcription factors. However, evidence for the direct interaction between this polyphenol and PPARs is lacking. Here, we addressed the hypothesis that resveratrol and its metabolites control aspects of PPAR transcriptional activity through direct interaction with PPARs. Bioaffinity chromatographic studies with the immobilized ligand-binding domains (LBDs) of PPARγ and PPARα and isothermal titration calorimetry allowed the binding affinities of resveratrol, resveratrol 3-O-glucuronide, resveratrol 4-O-glucuronide, and resveratrol 3-O-sulfate to both PPAR-LBDs to be determined. Interaction of resveratrol, resveratrol 3-O-glucuronide, and resveratrol 4-O-glucuronide with PPARγ-LBD occurred with binding affinities of 1.4, 1.1, and 0.8 μM, respectively, although only resveratrol bound to the PPARα-LBD with a binding affinity of 2.7 μM. Subsequently, X-ray crystallographic studies were carried out to characterize resveratrol binding to the PPARγ-LBD at the molecular level. The electron density map from the crystal structure of the complex between PPARγ-LBD and resveratrol revealed the presence of one molecule of resveratrol bound to the LBD of PPARγ, with the ligand occupying a position close to that of other known PPARγ ligands. Transactivation assays were also performed in HepG2 cells, with the results showing that resveratrol was not a PPAR agonist but instead was able to displace rosiglitazone from PPARγ and Wy-14643 from PPARα with IC50 values of (27.4±1.8) μM and (31.7±2.5) μM, respectively. We propose that resveratrol acts as a PPAR antagonist through its direct interaction with PPARγ and PPARα.

Open tubular columns containing the immobilized ligand binding domain of peroxisome proliferator-activated receptors α and γ for dual agonists characterization by frontal affinity chromatography with mass spectrometry detection

The peroxisome proliferator-activated receptors (PPARs) belong to the nuclear receptor superfamily. In the last years novel PPARs ligands have been identified and these include PPARα/γ dual agonists. To rapidly identify novel PPARs dual ligands, a robust binding assay amenable to high-throughput screening toward PPAR isoforms would be desirable. In this work we describe a parallel assay based on the principles of frontal affinity chromatography coupled to mass spectrometry (FAC-MS) that can be used to characterize dual agonists. For this purpose the ligand binding domain of PPARα receptor was immobilized onto the surface of open tubular capillaries to create new PPAR-alpha-OT columns to be used in parallel with PPAR-gamma-OT columns. The two biochromatographic systems were used in both ranking and Kd experiments toward new ureidofibrate-like dual agonists for subtype selectivity ratio determination. In order to validate the system, the Kd values determined by frontal analysis chromatography were compared to the affinity constants obtained by ITC experiments. The results of this study strongly demonstrate the specific nature of the interaction of the ligands with the two immobilized receptor subtypes.

New 2-(aryloxy)-3-phenylpropanoic acids as peroxisome proliferator-activated receptor α/γ dual agonists able to upregulate mitochondrial carnitine shuttle system gene expression

The preparation of a series of 2-(aryloxy)-3-phenylpropanoic acids, resulting from the introduction of different substituents into the biphenyl system of the previously reported peroxisome proliferator-activated receptor α/γ (PPARα/γ) dual agonist 1, allowed the identification of new ligands with higher potency on PPARα and fine-tuned moderate PPARγ activity. For the most promising stereoisomer (S)-16, X-ray and calorimetric studies in PPARγ revealed, at high ligand concentration, the presence of two molecules simultaneously bound to the receptor. On the basis of these results and docking experiments in both receptor subtypes, a molecular explanation was provided for its different behavior as a full and partial agonist of PPARα and PPARγ, respectively. The effects of (S)-16 on mitochondrial acylcarnitine carrier and carnitine-palmitoyl-transferase 1 gene expression, two key components of the carnitine shuttle system, were also investigated, allowing the hypothesis of a more beneficial pharmacological profile of this compound compared to the less potent PPARα agonist fibrates currently used in therapy.

Frontal affinity chromatography with MS detection of the ligand binding domain of PPARγ receptor: ligand affinity screening and stereoselective ligand-macromolecule interaction

In this study we report the development of new chromatographic tools for binding studies based on the gamma isoform ligand binding domain (LBD) of peroxisome proliferator-activated receptor (PPARγ) belonging to the nuclear receptor superfamily of ligand-activated transcription factors. PPARγ subtype plays important roles in the functions of adipocytes, muscles, and macrophages with a direct impact on type 2 diabetes, dyslipidemia, atherosclerosis, and cardiovascular disease. In order to set up a suitable immobilization chemistry, the LBD of PPARγ receptor was first covalently immobilized onto the surface of aminopropyl silica particles to create a PPARγ-Silica column for zonal elution experiments and then onto the surface of open tubular (OT) capillaries to create PPARγ-OT capillaries following different immobilization conditions. The capillaries were used in frontal affinity chromatography coupled to mass spectrometry (FAC-MS) experiments to determine the relative binding affinities of a series of chiral fibrates. The relative affinity orders obtained for these derivatives were consistent with the EC(50) values reported in literature. The optimized PPARγ-OT capillary was validated by determining the K(d) values of two selected compounds. Known the role of stereoselectivity in the binding of chiral fibrates, for the first time a detailed study was carried out by analysing two enantioselective couples on the LBD-PPARγ capillary by FAC and a characteristic two-stairs frontal profile was derived as the result of the two saturation events. All the obtained data indicate that the immobilized form of PPARγ-LBD retained the ability to specifically bind ligands.

A randomized trial of prolonged high dose of interferon plus ribavirin for hepatitis C patients nonresponders to interferon alone

Retreatment of chronic hepatitis C patients nonresponders to interferon (IFN) alone with the standard dose of IFN [3 million units (MU) thrice weekly (TIW)] plus ribavirin for 24 weeks has yielded low sustained virological response (SVR), averaging 8%. The aim of the present, open-labelled, randomized study was to evaluate the efficacy of IFN induction therapy followed by prolonged high dose of IFN plus ribavirin in nonresponders. One hundred and fifty-one patients were randomized to receive 5 MU daily of IFN alfa-2b (group 1, n = 73) or 5 MU TIW of IFN alfa 2b (group 2, n = 78) for 4 weeks followed by IFN (5 MU TIW) plus ribavirin (1000/1200 mg/daily) for 48 weeks in both groups. In an intention-to-treat analysis, the sustained virological response (SVR) at 24-week follow-up was 33 and 23% for group 1 and 2, respectively (P = 0.17). The overall SVR was 52 and 18% in patients with genotype 2/3 and 1/4, respectively. Among genotype 1/4 patients the SVR was 29 and 11% for age younger or older than 40 years. Compared with genotype 2/3 patients, the risk (95% confidence interval) of nonresponse to retreatment was 3.0-fold (1.17-8.0) in younger genotype 1/4 patients and 8.4-fold (3.0-23.29) in older genotype 1/4 patients. In conclusion these results suggest that retreatment with a reinforced regimen should be focused in nonresponder genotype 2/3 patients and younger genotype 1/4 patients, who are most likely to benefit. Induction therapy does not improve SVR.

Efficacy of prolonged 5 million units of interferon in combination with ribavirin for relapser patients with chronic hepatitis C

summary. Retreatment of relapser patients with chronic hepatitis C with the standard dose of interferon (IFN) of 3 million units (MU) thrice weekly (tiw) plus ribavirin for 24 weeks achieves a sustained response in 30 and 73% of patients with genotype 1 and 2 or 3, respectively. The aim of this study was to evaluate the efficacy and safety of IFN alpha-2b induction therapy, followed by prolonged treatment with a high dose of IFN alpha-2b plus ribavirin in relapser patients. A total of 119 patients were randomized to receive IFN alpha-2b 5 MU daily (Group A: 59 patients) or IFN alpha-2b 5 MU tiw (Group B: 60 patients) for 4 weeks followed by IFN (5 MU tiw) and ribavirin (1000-1200 mg/day) for 48 weeks in both groups. The primary end point was hepatitis C virus (HCV)-RNA clearance at week 24 after the end of treatment. A sustained virological response (SVR) was achieved in 68 and 60% of Group A and B patients, respectively (P = 0.37). Logistic regression analysis identified genotype 2 or 3 as the only independent factor associated with response, whereas induction regimen and baseline viraemia levels did not affect the response. The overall SVR was 53 and 72% in patients with genotype 1 or 4 and 2 or 3, respectively. In conclusion, induction IFN therapy does not enhance the SVR to a 48-week combination therapy. Our study suggests that relapsed patients with genotype 1 or 4 may achieve significant response rates of approximately 50%, if retreated with 5 MU tiw IFN plus ribavirin for 48 weeks.

Structures of solid and liquid during melting and solidification of indium

During melting and solidification of polycrystalline indium the structures of the solid and liquid phases were investigated by X-ray diffractometry (XRD) in 1g conditions. The experiments showed that melting is immediately preceded and accompanied by an abnormal increase of vacancy concentration in the solid that enhances the diffusion. At the melting point (T(M)) the lattice planes facing the first formed liquid appear to be [002] and [101]; that is, those planes allocating first and second neighbors around a given atom, with shell radii very close to the mean distance of nearest neighbors in liquid as obtained from the radial distribution function (RDF). On this basis some types of solid-liquid interface (sharp or diffuse) are discussed; the possibility of a sudden texture change in the solid is also considered. On the other hand, the evolution of RDF curve of liquid indium, cooled down through T(M), shows that there are correlations between the structure of the liquid and of the forming solid during solidification. To avoid convective motions in the liquid and to achieve the best experimental conditions, we discuss the possibility of repeating the measurements in microgravity (microg) using thin oxide films as containers. This technique was already successfully tested by one of the investigators in the experiment ES 311 A-B carried out during the mission SPACELAB-1.

[Incidence of chromosomal anomalies and congenital malformations in children born from assisted fertilization]

The introduction and widespread application of Assisted Reproductive Techniques (ART) have raised major concern about the offspring 's health. The incidence of congenital and chromosomal anomalies after standard In Vitro Fertilization and Embryo Transfer seems to be similar to that expected in the general population. The prevalence of congenital malformations does not seem to be higher in children conceived by ICSI. On the other hand, it seems that there is a slight risk for transmission of chromosomal aberration of paternal origin and a certain risk of de novo sex-chromosomal and structural aberrations after ICSI. We report the results of the follow-up of 938 children conceived in our public ART by standard IVF(649) and by ICSI(289) from 21-2-1987 to 30-6-1999. The incidence of the congenital malformations results of the 1.8% (17/938); the incidence of chromosomal anomalies results 0.5% (5/938). The incidence of congenital malformations and chromosomal anomalies results 1.5% (10/649) and 0.6% (4/649), respectively, for standard IVF and 2.4% (7/289) and 0.3% (1/289) for ICSI. Our data seems to be reassuring but the incidence of chromosomal anomalies in ICSI children needs further investigation.

The role of diagnostic hysteroscopy and endometrial biopsy in assisted reproductive technologies

OBJECTIVE

To study the incidence of unsuspected endouterine abnormalities in patients for whom IVF-ET repeatedly fails.

DESIGN

Prospective study.

SETTING

Infertility Unit of the Department of Obstetrics and Gynecology, Arcispedale Santa Maria Nuova, Reggio Emilia, Italy.

PATIENT(S)

One hundred patients for whom two IVF-ET cycles failed in which > or =2 good-quality embryos were transferred.

INTERVENTION(S)

In-office diagnostic hysteroscopy and endometrial biopsy.

MAIN OUTCOME MEASURE(S)

Relation between IVF-ET failure and unsuspected endouterine abnormalities.

RESULT(S)

In 18 patients, hysteroscopy showed an important unsuspected endouterine abnormality. Fifteen of these patients did not become pregnant after IVF-ET, and 3 became pregnant but had a spontaneous abortion. Histologic examination of the endometrium revealed chronic endometritis in 1 patient and tuberculous endometritis in another.

CONCLUSION(S)

Previous studies have reported that the incidence of endouterine abnormalities is high in patients undergoing IVF-ET. Our data confirm the previous reports and lead us to conclude that diagnostic hysteroscopy should be performed on all patients before they undergo IVF-ET.