Toward a global description of the nucleus-nucleus interaction

Extensive systematizations of theoretical and experimental nuclear densities and of optical potential strengths extracted from heavy-ion elastic scattering data analyses at low and intermediate energies are presented. The energy dependence of the nuclear potential is accounted for within a model based on the nonlocal nature of the interaction. The systematics indicates that the heavy-ion nuclear potential can be described in a simple global way through a double-folding shape, which basically depends only on the density of nucleons of the partners in the collision. The possibility of extracting information about the nucleon-nucleon interaction from the heavy-ion potential is investigated.

Expression and variability of molecular chaperones in the sugarcane expressome

Molecular chaperones perform folding assistance in newly synthesized polypeptides preventing aggregation processes, recovering proteins from aggregates, among other important cellular functions. Thus their study presents great biotechnological importance. The present work discusses the mining for chaperone-related sequences within the sugarcane EST genome project database, which resulted in approximately 300 different sequences. Since molecular chaperones are highly conserved in most organisms studied so far, the number of sequences related to these proteins in sugarcane was very similar to the number found in the Arabidopsis thaliana genome. The Hsp70 family was the main molecular chaperone system present in the sugarcane expressome. However, many other relevant molecular chaperones systems were also present. A digital RNA blot analysis showed that 5'ESTs from all molecular chaperones were found in every sugarcane library, despite their heterogeneous expression profiles. The results presented here suggest the importance of molecular chaperones to polypeptide metabolism in sugarcane cells, based on their abundance and variability. Finally, these data have being used to guide more in deep analysis, permitting the choice of specific targets to study. (c) 2006 Elsevier GmbH. All rights reserved.

The Araguaia fold belt, Brazil: A reactivated Brasiliano-Pan-African cycle (550 Ma) geosuture

The Araguaia-Tocantins geosuture, which separates the Araguaia Fold Belt (AFB) from the Archean Amazonian Craton, was active in the late Middle Proterozoic. The Baixo Araguaia Supergroup was deposited, consisting of the Estrondo Group (lower quartzites with intercalated schists), Xambioá Formation (schists), and Canto da Vazante Formation (upper feldspathic schists); and the Tocantins Group consisting of the Couto Magalhaës Formation (phyllites, quartzites, slates, limestones, and metacherts) and Pequizeiro Formation (upper chlorite schists); and associated mafic-ultramafic bodies. The deformational history includes four regional phases of deformation within this supracrustal sequence: recumbent folds with vergence to the west; refolding with a N-S trend; an intense crenulation episode; and late thrusting from east to west. Metamorphism is of intermediate or intermediate-high pressure type with garnet, biotite, chlorite, and sericite isograds succeeded by a slightly or non-metamorphosed zone, from east to west. Rocks surrounding sparse gneissic-cored domes contain isograds of staurolite, kyanite, and fibrolite. These isograds are believed to be associated with the 1100 Ma Uruaçuano event. The Brasiliano Orogeny strongly affected the AFB with displacements due to transcurrent reactivation of great and old faults of the basement, slight folding in the supracrustal sequence, intrusion of small granite bodies, and development of domes with associated normal faults. The area underlain by the Estrondo Group was uplifted at this time, causing the deposition of the Rio das Barreiras polymictic conglomerate of the central area. K-Ar and Rb-Sr analyses date this thermo-tectonic event at 550 ± 100 Ma. The Archean basement is exposed in the cores of domes as a granite-gneiss association, the Colméia complex, which shows thermo-tectonic features that may be interpreted as polycyclic imprints (Jequié, Transamazonian?, Uruaçuano, and Brasiliano Events). © 1989.

Structures of the noncovalent complexes of human and bovine prothrombin fragment 2 with human PPACK-thrombin

Both human and bovine prothrombin fragment 2 (the second kringle) have been cocrystallized separately with human PPACK (D-Phe-Pro-Arg)-thrombin, and the structures of these noncovalent complexes have been determined and refined (R = 0.155 and 0.157, respectively) at 3.3-Å resolution using X-ray crystallographic methods. The kringles interact with thrombin at a site that has previously been proposed to be the heparin binding region. The latter is a highly electropositive surface near the C-terminal helix of thrombin abundant in arginine and lysine residues. These form salt bridges with acidic side chains of kringle 2. Somewhat unexpectedly, the negative groups of the kringle correspond to an enlarged anionic center of the lysine binding site of lysine binding kringles such as plasminogens K1 and K4 and TPA K2. The anionic motif is DGDEE in prothrombin kringle 2. The corresponding cationic center of the lysine binding site region has an unfavorable Arg70Asp substitution, but Lys35 is conserved. However, the folding of fragment 2 is different from that of prothrombin kringle 1 and other kringles: the second outer loop possesses a distorted two-turn helix, and the hairpin β-turn of the second inner loop pivots at Val64 and Asp70 by 60°. Lys35 is located on a turn of the helix, which causes it to project into solvent space in the fragment 2-thrombin complex, thereby devastating any vestige of the cationic center of the lysine binding site. Since fragment 2 has not been reported to bind lysine, it most likely has a different inherent folding conformation for the second outer loop, as has also been observed to be the case with TPA K2 and the urokinase kringle. The movement of the Val64-Asp70 β-turn is most likely a conformational change accompanying complexation, which reveals a new heretofore unsuspected flexibility in kringles. The fragment 2-thrombin complex is only the second cassette module-catalytic domain structure to be determined for a multidomain blood protein and only the third domain-domain interaction to be described among such proteins, the others being factor Xa without a Gla domain and Ca2+ prothrombin fragment 1 with a Gla domain and a kringle. © 1993 American Chemical Society.

Dobras em bainha macroscopicas relacionadas ao cisalhamento ductil de baixo angulo da nappe Araxa-Canastra no sudoeste de Minas Gerais

In the Proterozoic fold-thrust belt of Southwestern Minas Gerais, sheath folds belonging to Araxa-Canastra Group were mapped. These structures are explained by a tangential shear related to nappe transport, which acted together with an additional transcurrent shear, driven by a lateral ramp. An interesting feature recognized in these sheath folds is the striking obliquity between the hinge line of the macro structure and the hinge lines of the parasitic folds in the sheath fold closure. -English summary

Northwestern overthrusting and related lateral escape during the Brasiliano orogeny north of the Patos lineament, Borborema province, northeast Brazil

The Borborema province (BP) of northeastern Brazil, located between the São Luís and São Francisco cratons, represents a branching system of Precambrian orogens of the South American platform. It is composed of segments of Archean and Proterozoic crust that were deformed by the convergence of the West African and São Francisco-Congo cratons during assembly of the Brasiliano collage (650 to 500 Ma), a period of intense orogenic activity considered to be the strongest and most pervasive tectonic event that affected the Precambrian of the South American platform. The tectonic and kinematic history of the Brasiliano/Panafrican orogeny is fundamental for reconstructing South American and African Precambrian geology. The correlation between Neoproterozoic tectonic processes occurring in both continents should use structural elements, of regional or local character, with identical kinematic and metamorphic conditions manifested in both basement and supracrustal units. North of the Patos shear zone, subhorizontal Brasiliano thrusts (0.65 to 0.58 Ga) affected the basement and the supracrustal Seridó belt with such related regional D1/D2 structures as foliation, lineation, isoclinal folds, and related metamorphism. Overprinting the previous structures, regional folding with a vertical S3 foliation and an associated strike-slip shear zone were developed (0.58 to 0.52 Ga). The metamorphism is similar for all deformation phases, ranging from upper-greenschist to amphibolite facies with mineral assemblages including biolite and garnet throughout the Seridó fold belt. We propose, on the basis of deformational and kinematic reconstructions, that the structural evolution of the Seridó fold belt was characterized by transition from a syn-collisional to a strike-slip regime. The transition between regimes occurred, progressively or instantaneously, by the switching of the maximum and intermediary strain axes of the strain ellipsoid. The entire tectonic history can be related to a frontal or oblique collision and lateral escape tectonics, with local, syn-collisional transpression and transtension. The Patos shear zone represents a final vertical shearing, juxtaposing different terranes of the northern and southern Borborema province.

Nonlocal description of the nucleus-nucleus interaction

A parameter-free nonlocal double-folding-inspired interaction is proposed for the nucleus-nucleus systems. Excellent reproductions of elastic scattering differential cross section data were obtained for several systems over a wide range of bombarding energies. Our results should be of value in the description of the scattering of other many-body systems.

Collagen fibers in human prostatic lesions: histochemistry and anisotropies

The present study focuses on establishing patterns of collagen fibers distribution in prostatic nodular hyperplasia and adenocarcinomas, in comparison with the normal tissue. Sections of prostatic transurethral resection were subjected to Gömöri's method for collagen fibers and reticulin and analyzed under ordinary and polarized light microscopy. Controls and hyperplastic regions present collagen fibers with variable thickness that run in different directions, establishing a tridimensional network. These fibers exhibit birefringence and dichroism thus demonstrating their fibrillar integrity. On the other hand, increased variability in collagen fiber distribution and anisotropical properties occur in adenocarcinomas evaluated in accordance with the Gleason's score. In some of their areas, a well-defined collagen network delimitates the base of transformed epithelial cells whereas in other areas the collagen fibers are disorganized and do not establish a boundary between the epithelial structures and the stroma. In these areas, collagen is found in the stroma. It was also observed that adenocarcinoma tumor cells rest on a scaffold of thin and dendritic collagen fibers. Collagen fibers of the prostatic stroma of the adenocarcinomas may show a modification in arrangement and fibrillar compactness. In prostatic nodular hyperplasia, there is no change in collagen molecular integrity, since collagen affinity for silver and collagen birefringence are similar to controls. In adenocarcinoma with high dedifferentiation degree, thin and branched strongly argyrophilic and birefringent collagen fibers are detected in regions of cell proliferation. In the adjacent stroma, hyaline plaques are indicative of matrix degradation or remodellation.

Características estruturais da parede das artérias renal e femoral de coelho (Oryctolagus cuniculus)

In the renal and femoral arteries of rabbit was verified that both vessels had walls structured by myostromal components, despite of their different distributive of blood, being the renal artery a visceral blood vessel and the femoral artery a parietal vessel. This wall pattern in these vessels concerned to presence of connective stromal elements (collagen and elastic fibres and lamellae) and smooth muscle cells coexisting with some equilibrium in the wall structure of the renal and femoral arteries, mainly in the medial layer architecture. An intimal folding pattern was verified around the vascular lumen, possibly related to capacitance of the both arteries regarding to variability of pressure levels in cardiac cycle. Furthermore, myostromal relations of connective elements and smooth muscle cells verified in the medial layer and the network formed by connective elements in the adventitial layer of these arteries contributed to maintenance of wall viscoelasticity properties of the vessels.

Conformational basis for the biological activity of TOAC-labeled angiotensin II and bradykinin: Electron paramagnetic resonance, circular dichroism, and fluorescence studies

N-Terminally and internally labeled analogues of the hormones angiotensin (AII, DRVYIHPF) and bradykinin (BK, RPPGFSPFR) were synthesized containing the paramagnetic amino acid 2,2,6,6-tetramethylpiperidine-1-oxyl-4-amino-4- carboxylic acid (TOAC). TOAC replaced Asp 1 (TOAC 1-AII) and Val 3 (TOAC 3-AII) in AII and was inserted prior to Arg 1 (TOAC 0-BK) and replacing Pro 3 (TOAC 3-BK) in BK. The peptide conformational properties were examined as a function of trifluoroethanol (TFE) content and pH. Electron paramagnetic resonance spectra were sensitive to both variables and showed that internally labeled analogues yielded rotational correlation times (TC) considerably larger than N-terminally labeled ones, evincing the greater freedom of motion of the N-terminus. In TFE, τ C increased due to viscosity effects. Calculation of τ Cpeptide/τ CTOAC ratios indicated that the peptides acquired more folded conformations. Circular dichroism spectra showed that, except for TOAC 1-AII in TFE, the N-terminally labeled analogues displayed a conformational behavior similar to that of the parent peptides. In contrast, under all conditions, the TOAC 3 derivatives acquired more restricted conformations. Fluorescence spectra of All and its derivatives were especially sensitive to the ionization of Tyr 4. Fluorescence quenching by the nitroxide moiety was much more pronounced for TOAC 3-AII The conformational behavior of the TOAC derivatives bears excellent correlation with their biological activity, since, while the N-terminally labeled peptides were partially active, their internally labeled counterparts were inactive [Nakaie, C. R., et al., Peptides 2002, 23, 65-70]. The data demonstrate that insertion of TOAC in the middle of the peptide chain induces conformational restrictions that lead to loss of backbone flexibility, not allowing the peptides to acquire their receptor-bound conformation. © 2004 Wiley Periodicals, Inc.

Low ethanol consumption induces enhancement of insulin sensitivity in liver of normal rats

Moderate amounts of alcohol intake have been reported to have a protective effect on the cardiovascular system and this may involve enhanced insulin sensitivity. We established an animal model of increased insulin sensitivity by low ethanol consumption and here we investigated metabolic parameters and molecular mechanisms potentially involved in this phenomenon. For that, Wistar rats have received drinking water either without (control) or with 3% ethanol for four weeks. The effect of ethanol intake on insulin sensitivity was analyzed by insulin resistance index (HOMA-IR), intravenous insulin tolerance test (IVITT) and lipid profile. The role of liver was investigated by the analysis of insulin signaling pathway, GLUT2 gene expression and tissue glycogen content. Rats consuming 3% ethanol showed lower values of HOMA-IR and plasma free fatty acids (FFA) levels and higher hepatic glycogen content and glucose disappearance constant during the IVITT. Neither the phosphorylation of insulin receptor (IR) and insulin receptor substrate-1 (IRS-1), nor its association with phosphatidylinositol-3-kinase (PI3-kinase), was affected by ethanol. However, ethanol consumption enhanced liver IRS-2 and protein kinase B (Akt) phosphorylation (3 times, P < 0.05), which can be involved in the 2-fold increased (P < 0.05) hepatic glycogen content. The GLUT2 protein content was unchanged. Our findings point out that liver plays a role in enhanced insulin sensitivity induced by low ethanol consumption. © 2005 Elsevier Inc. All rights reserved.

GnRH agonist versus GnRH antagonist in poor ovarian responders: A meta-analysis

The aim of this meta-analysis was to compare the efficacy of gonadotrophin antagonist (GnRH-ant) versus GnRH agonist (GnRHa) as coadjuvant therapy for ovarian stimulation in poor ovarian responders in IVF/intracytoplasmic sperm injection cycles. Search strategies included on-line surveys of databases such as MEDLINE, EMBASE and others. A fixed effects model was used for odds ratio (OR) and effect size (weighted mean difference, WMD). Six trials fulfilled the inclusion criteria (randomized controlled trials). There was no difference between GnRH-ant and GnRHa (long and flare-up protocols) with respect to cycle cancellation rate, number of mature oocytes and clinical pregnancy rate per cycle initiated, per oocyte retrieval and per embryo transfer. When the mete-analysis was applied to the two trials that had used GnRH-ant versus long protocols of GnRHa, a significantly higher number of retrieved oocytes was observed in the GnRH-ant protocols [P = 0.018; WMD: 1.12 (0.18, 2.05)]. However, when the meta-analysis was applied to the four trials that had used GnRH-ant versus flare-up protocols, a significantly higher number of retrieved oocytes (P = 0.032; WMD: -0.51, 95% CI -0.99, -0.04) was observed in the GnRHa protocols. Nevertheless, additional randomized controlled trials with better planning are needed to confirm these results.

The inhibition of 5-enolpyruvylshikimate-3-phosphate synthase as a model for development of novel antimicrobials

EPSP synthase (EPSPS) is an essential enzyme in the shikimate pathway, transferring the enolpyruvyl group of phosphoenolpyruvate to shikimate-3-phosphate to form 5-enolpyruvyl-3-shikimate phosphate and inorganic phosphate. This enzyme is composed of two domains, which are formed by three copies of βαβαββ-folding units; in between there are two crossover chain segments hinging the nearly topologically symmetrical domains together and allowing conformational changes necessary for substrate conversion. The reaction is ordered with shikimate-3-phosphate binding first, followed by phosphoenolpyruvate, and then by the subsequent release of phosphate and EPSP. N-[phosphomethyl]glycine (glyphosate) is the commercial inhibitor of this enzyme. Apparently, the binding of shikimate-3-phosphate is necessary for glyphosate binding, since it induces the closure of the two domains to form the active site in the interdomain cleft. However, it is somehow controversial whether binding of shikimate-3-phosphate alone is enough to induce the complete conversion to the closed state. The phosphoenolpyruvate binding site seems to be located mainly on the C-terminal domain, while the binding site of shikimate-3-phosphate is located primarily in the N-terminal domain residues. However, recent results demonstrate that the active site of the enzyme undergoes structural changes upon inhibitor binding on a scale that cannot be predicted by conventional computational methods. Studies of molecular docking based on the interaction of known EPSPS structures with (R)- phosphonate TI analogue reveal that more experimental data on the structure and dynamics of various EPSPS-ligand complexes are needed to more effectively apply structure-based drug design of this enzyme in the future. © 2007 Bentham Science Publishers Ltd.

Orphan nuclear receptor NGFI-B forms dimers with nonclassical interface

The orphan receptor nerve growth factor-induced B (NGFI-B) is a member of the nuclear receptor's subfamily 4A (Nr4a). NGFI-B was shown to be capable of binding both as a monomer to an extended half-site containing a single AAAGGTCA motif and also as a homodimer to a widely separated everted repeat, as opposed to a large number of nuclear receptors that recognize and bind specific DNA sequences predominantly as homo- and/or heterodimers. To unveil the structural organization of NGFI-B in solution, we determined the quaternary structure of the NGFI-B LBD by a combination of ab initio procedures from small-angle X-ray scattering (SAXS) data and hydrogen-deuterium exchange followed by mass spectrometry. Here we report that the protein forms dimers in solution with a radius of gyration of 2.9 nm and maximum dimension of 9.0 nm. We also show that the NGFI-B LBD dimer is V-shaped, with the opening angle significantly larger than that of classical dimer's exemplified by estrogen receptor (ER) or retinoid X receptor (RXR). Surprisingly, NGFI-B dimers formation does not occur via the classical nuclear receptor dimerization interface exemplified by ER and RXR, but instead, involves an extended surface area composed of the loop between helices 3 and 4 and C-terminal fraction of the helix 3. Remarkably, the NGFI-B dimer interface is similar to the dimerization interface earlier revealed for glucocorticoid nuclear receptor (GR), which might be relevant to the recognition of cognate DNA response elements by NGFI-B and to antagonism of NGFI-B-dependent transcription exercised by GR in cells. Published by Cold Spring Harbor Laboratory Press. Copyright © 2007 The Protein Society.

Studying the satisfaction of patients on the outcome of an aesthetic dermatological filler treatment

Background: Many factors contribute to extend productive life in the modern world. Competition makes people worry about physical appearance, mosftly in respect to facial and skin aging. This has motivated new developments in cosmetic dermatology and the need of evaluating patient satisfaction with the new proposed treatments. Poll questionnaire has been used for such evaluation, and the analysis of the electroencephalogram (EEG) mapping obtained while the patient answers the satisfaction questionnaire may render the results less subjective. Objectives: The purpose of this paper is to study the satisfaction of a group of 33 women (mean age, 44.years) treated with hyaluronic acid filling of nasolabial folding or lips, combining the EEG brain mapping and questionnaire techniques. Methods: At the third month of evaluation, two networked personal computers were used for the EEG recording and for presenting the patient with a questionnaire about her well-being feeling; self-evaluation of her face; her satisfaction with the results of the aesthetic treatment; how the family, friends, and people at work evaluated the result of the treatment; and her decision to repeat the treatment and to recommend it to friends and family. Results: Poll results showed that patients were feeling well and were satisfied with the results of the aesthetic treatment. Furthermore, the regression EEG mappings showed patients to be satisfied with their appearance and with the treatment involving similar brain areas. Conclusion: Patients decided to undergo the treatment because they were already considering it (54%) or because they were dissatisfied with their lips or nasolabial folding (52%). The fact that the treatment was free of charge solidified the decision. Patients consider themselves as good-looking and they wanted to preserve such a condition. © 2008 Wiley Periodicals, Inc.