Endothelial dysfunction in DOCA-salt hypertension - Possible involvement of prostaglandin endoperoxides

The effects of the arachidonic acid metabolism inhibitors on the acetylcholine responses of aortae from control (CR) and deoxycorticosterone acetate (DOCA)-salt hypertensive (HR) rats were investigated. The acetylcholine decreased response observed in HR [relaxation (%): CR 95.5 +/- 2.7, n = 4; HR 52.0 +/- 6.3, n = 5, p < 0.05] was restored by the cyclooxygenase inhibitor piroxicam [relaxation (%): CR 99.8 +/- 0.2, n = 4; HR 86.0 +/- 4.0, n = 5] and by the thromboxane synthetase inhibitor and the thrombox ane A(2)/prostaglandin H-2 receptor antagonist ridogrel [relaxation (%): CR 92.1 +/- 4.4, n = 7; HR 93.1 +/- 2.0, n = 7] but not by the inhibitors of thromboxane synthetase, prostacyclin synthetase, cytochrome P-450 monooxygenase, and lipoxygenase. So, endoperoxide intermediates seem to be involved in the decreased endothelium-dependent relaxation to acetylcholine in DOCA-salt hypertension. (C) 1999 Elsevier B.V. All rights reserved.

Modulation of intercellular communication in macrophages: possible interactions between GAP junctions and P2 receptors

Gap junctions are connexin-formed channels that play an important role in intercellular communication in most cell types. In the immune system, specifically in macrophages, the expression of connexins and the establishment of functional gap junctions are still controversial issues. Macrophages express P2X(7) receptors that, once activated by the binding of extracellular ATP, lead to the opening of transmembrane pores permeable to molecules of up to 900 Da. There is evidence suggesting an interplay between gap junctions and P2 receptors in different cell systems. Thus, we used ATP-sensitive and -insensitive J774.G8 macrophage cell lines to investigate this interplay. To study junctional communication in J774-macrophage-like cells, we assessed cell-to-cell communication by microinjecting Lucifer Yellow. Confluent cultures of ATP-sensitive J774 cells (ATP-s cells) are coupled, whereas ATP-insensitive J774 cells (ATP-i cells), derived by overexposing J774 cells to extracellular ATP until they do not display the phenomenon of ATP-induced permeabilization, are essentially uncoupled. Western-blot and reverse-transcription polymerase chain reaction assays revealed that ATP-s and ATP-i cells express connexin43 (Cx43), whereas only ATP-s cells express the P2X(7) receptor. Accordingly, ATP-i cells did not display any detectable ATP-induced current under whole-cell patch-clamp recordings. Using immunofluorescence microscopy, Cx43 reactivity was found at the cell surface and in regions of cell-cell contact of ATP-s cells, whereas, in ATP-i cells, Cx43 immunoreactivity was only present in cytosolic compartments. Using confocal microscopy, it is shown here that, in ATP-s cells as well as in peritoneal macrophages, Cx43 and P2X(7) receptors are co-localized to the membrane of ATP-s cells and peritoneal macrophages.

Exotic species of freshwater decapod crustaceans in the state of São Paulo, Brazil: records and possible causes of their introduction

Based on recent surveys of the freshwater decapod fauna, distributional data of five exotic species of freshwater decapod crustaceans for the hydrographic basins of the state of São Paulo are presented, as part of a large initiative for a comprehensive survey of the state's biodiversity (BIOTA-FAPESP Program). These species are the North American crayfish Procambarus clarkii (Girard) (Cambaridae), the crab Dilocarcinus pagei Stimpson (Trichodactylidae) from the Amazon and Paraguay/lower Parana River Basins, and the palaemonid shrimps Macrobrachium rosenbergii (De Man), from the Indo-Pacific region, Macrobrachium amazonicum (Heller) and Macrobrachium jelskii (Miers), both from the Orinoco, Amazon and the Paraguay/lower Parana River Basins. Possible modes by which their introduction might have occurred are commented upon and potential consequences are discussed.

Reduction of mercury(II) by tropical river humic substances (Rio Negro) - A possible process of the mercury cycle in Brazil

The evolution of elemental Hg from its environmental compounds has already been supposed to be an important process within the global mercury cycle. The present study characterizes the abiotic reduction of Hg(II) ions by typical river humic substances (HS) conventionally pre-isolated by the adsorbent XAD 8 from the Rio Negro near Manaus, Brazil. For the investigation of this reduction process a special reaction and Hg(0) trapping unit combined with cold-vapor atomic absorption spectrometry (CVAAS) was developed. Preconcentration of traces of mercury(II), if required, was obtained by a home-made FIA system using microcolumns filled with the Hg(II)-selective collector CheliteS(R) (Serva Company). The effect of environmentally relevant parameters such as the pH value, the Hg(II)/HS ratio and the HS concentration on the I-IE;(II) reduction process was studied as a function of the time. The Hg(0) production was highest at pH 8.0 and in the case of decreasing HS amounts (0.5 mg) when about 65% of initially 1.0 mug Hg(H) was reduced within 50 h. Moreover, the reduction efficiency of HS towards HE;(II) strongly depended on the HS concentration but hardly on the Hg(II)/HS ratio. The reduction kinetics followed a relatively slow two-step first-order mechanism with formal rate constants of about 0.1 and 0.02 h(-1), respectively. Based on these findings the possible relevance of the abiotic evolution of mercury in humic-rich aquatic environments is considered. (C) 2000 Elsevier B.V. B.V. All rights reserved.

An eco-friendly protocol for synthesis of thiourea derivatives: 1-benzoyl-3-benzylguanidine and 1-benzoyl-3-benzyl-O-ethylisourea. A possible non-purely thermal microwave assisted reaction

1-Benzoyl-3-benzylguanidine and 1-benzoyl-3-benzyl-O-ethylisourea were synthesized in good yields (68 and 76%, respectively) from 1-benzoyl-3-benzylthiourea and benzoyl-ethylthiocarbamate in dry media conditions using KF-Al2O3 under microwave irradiation. Strong nucleophilic amines promoted the sulfur elimination by attack on the thiocarbonyl group in both thiourea and thiocarbamates to afford guanidines and isourea, respectively. Transesterification products were obtained from p-TsOH catalyzed reaction of thiocarbamate with alcohols under MW-solvent-free conditions. Very important non-purely thermal MW specific effects were evidenced and attributed to stabilization by coulombic interactions between materials and waves. (c) 2005 Elsevier Ltd. All rights reserved.

An insight into the theoretical investigation of possible piezoelectric effect in samarium titanate (SmTiO3)

Conselho Nacional de Desenvolvimento Científico e Tecnológico (CNPq)

Possible implication of Mdm2 as a prognostic marker in invasive laryngeal carcinoma

Conselho Nacional de Desenvolvimento Científico e Tecnológico (CNPq)

New approach to four-phase transmission systems: analysis of the transient response and the possible voltage surges

This study describes a technical analysis of a four-phase line as a transmission system alternative. An analysis in the frequency and the time domains is performed to evaluate the electrical characteristics and the transient response of a generic four-phase system compared with those of a conventional three-phase transmission system. The technical features of this non-conventional system are discussed and reviewed based on the current literature. Thus, a new analysis of the four-phase system is presented that emphasises several technical characteristics that have not been discussed in previous studies.

Possible shunt compensation strategies based on Conservative Power Theory

Considering the Conservative Power Theory (CPT), this paper proposes some novel compensation strategies for shunt passive or active devices. The CPT current decompositions result in several current terms (associated with specific physical phenomena), which were used for the definition of different selective current compensators, in terms of minimizing particular disturbing effects. Simulation results have been demonstrated in order to validate the possibilities and performance of the proposed strategies for single and three-phase four wired circuits.

A possible tricritical line in Ni(NO3)2 · 2H2O

We obtain the behaviour of the critical (possibly tricritical) point for metamagnetic Ni(NO3)2·2H2O as a function of several applied hydrostatic pressures up to 11 kbar. The obtained line of possible tricritical points greatly suggests a pressure induced metamagnetic transition in a 0.8 kbar range. © 1987.

Expression of beta-human chorionic gonadotropin (beta-hCG) in non-trophoblastic elements of transitional cell carcinoma of the bladder: possible relationship with the prognosis.

Transitional cell carcinoma (TCC) of the bladder is a neoplasm with variability in its clinical behavior. Although there are several studies correlating stage and ABO isoantigen expression with invasiveness, there is no single predictor factor to assess the potential invasiveness, especially in the low grade, non-invasive TCC. In the present study we evaluated the correlation of histological grade plus stage and the expression of beta human chorionic gonadotropin (beta-hCG), in 100 cases of TCC, with the clinical behavior. These features were correlated with tumor progression in patients with at least two years of follow up. We observed more aggressiveness in G4 group (high grade and invasive) (93% had tumor progression) when compared to G1 group (low grade and superficial) (11% had tumor progression). However in 25.5% of the TCC cases (groups G2: low grade and invasive and G3: high grade and superficial) the clinical behavior was intermediate, showing some limitation in using grading and staging only, as a predictive factor. There was an expression of beta-hCG in 21.4% of the cases in up to 25% of the tumor cells without any trophoblastic morphology. These beta-hCG producing TCC had a strong correlation with aggressiveness: 39.1% and 12.8% of the TCC expressed beta-hCG with and without tumor progression, respectively.

On a possible dual role for central noradrenaline in the control of hydromineral fluid intake

Noradrenaline (NOR) is a neurotransmitter presenl in the central nervous system which is related to the control of ingestive behavior of food and fluids. We describe here the relationship between NOR and intake of water and NaCl solution, fluids that are essential for a normal body fluid electrolytic balance. Central NOR has an inhibitory effect on fluid intake, but it either induces or not alterations in food intake. Several ways of inducing water intake, such as water deprivation, meal-associated water intake, administration of angiotensinergic, cholinergic or beta-adrenergic agonists, or administration of hyperosmotic solutions, are inhibited by alpha-adrenergic agonists. Need-induced sodium intake by sodium-depleted animals is also inhibited by alpha-adrenergic agonists. NOR can also facilitate fluid intake. Water intake is elicited by NOR and the integrity of central noradrenergic systems is necessary for a normal expression of water or salt intake in dehydrated animals. The angiotensinergic component of either behavior apparently depends on a central noradrenergic system. NOR probably facililates fluid intake by acting on postsynaptic receptors, but we do not know how it inhibits fluid infake. The inhibitory and facilitatory effects of NOR on ingestive behavior suggest a dual role for this neurotransmitter in the control of hydromineral fluid intake.

Scaling law for baryon coupling to its current and its possible applications

The baryon coupling to its current (λB), in conventional QCD sum rule calculations (QCDSR), is shown to scale as the cubic power of the baryon mass, MB. Some theoretical justification for it comes from a simple light-cone model and also general scaling arguments for QCD. But more importantly, taken as a phenomenological ansatz for the present, this may find very good use in current explorations of possible applications of QCDSR to baryon physics both at temperature T = 0, T ≠ 0 and/or density ρ = 0, ρ ≠ 0. © World Scientific Publishing Company.