Nonlocal Transport Near Charge Neutrality Point in a Two-Dimensional Electron-Hole System

Nonlocal resistance is studied in a two-dimensional system with a simultaneous presence of electrons and holes in a 20 nm HgTe quantum well. A large nonlocal electric response is found near the charge neutrality point in the presence of a perpendicular magnetic field. We attribute the observed nonlocality to the edge state transport via counterpropagating chiral modes similar to the quantum spin Hall effect at a zero magnetic field and graphene near a Landau filling factor nu = 0.

Effective carrying capacity and analytical solution of a particular case of the Richards-like two-species population dynamics model

We consider a generalized two-species population dynamic model and analytically solve it for the amensalism and commensalism ecological interactions. These two-species models can be simplified to a one-species model with a time dependent extrinsic growth factor. With a one-species model with an effective carrying capacity one is able to retrieve the steady state solutions of the previous one-species model. The equivalence obtained between the effective carrying capacity and the extrinsic growth factor is complete only for a particular case, the Gompertz model. Here we unveil important aspects of sigmoid growth curves, which are relevant to growth processes and population dynamics. (C) 2011 Elsevier B.V. All rights reserved.

Divertor map with freedom of geometry and safety factor profile

An explicit, area-preserving and integrable magnetic field line map for a single-null divertor tokamak is obtained using a trajectory integration method to represent equilibrium magnetic surfaces. The magnetic surfaces obtained from the map are capable of fitting different geometries with freely specified position of the X-point, by varying free model parameters. The safety factor profile of the map is independent of the geometric parameters and can also be chosen arbitrarily. The divertor integrable map is composed of a nonintegrable map that simulates the effect of external symmetry-breaking resonances, so as to generate a chaotic region near the separatrix passing through the X-point. The composed field line map is used to analyze escape patterns (the connection length distribution and magnetic footprints on the divertor plate) for two equilibrium configurations with different magnetic shear profiles at the plasma edge.

Leprosy reactions: coinfections as a possible risk factor

OBJECTIVE: This study aimed to determine the frequency of coinfections in leprosy patients and whether there is a relationship between the presence of coinfections and the development of leprosy reactional episodes. METHOD: A cross-sectional study based on an analysis of the medical records of the patients who were treated at the Leprosy Clinics of the Ribeirao Preto Medical School, University of Sao Paulo, was conducted from 2000 to 2010. Information was recorded regarding the age, sex, clinical status, WHO classification, treatment, presence of reactions and coinfections. Focal and systemic infections were diagnosed based on the history, physical examination, and laboratory tests. Multinomial logistic regression was used to evaluate the associations between the leprosy reactions and the patients' gender, age, WHO classification and coinfections. RESULTS: Two hundred twenty-five patients were studied. Most of these patients were males (155/225 = 68.8%) of an average age of 49.31 +/- 15.92 years, and the most prevalent clinical manifestation was the multibacillary (MB) form (n = 146), followed by the paucibacillary (PB) form (n = 79). Erythema nodosum leprosum (ENL) was more prevalent (78/122 = 63.9%) than the reversal reaction (RR) (44/122 = 36.1%), especially in the MB patients (OR 5.07; CI 2.86-8.99; p<0.0001) who exhibited coinfections (OR 2.26; CI 1.56-3.27; p<0.0001). Eighty-eight (88/225 = 39.1%) patients exhibited coinfections. Oral coinfections were the most prevalent (40/88 = 45.5%), followed by urinary tract infections (17/88 = 19.3%), sinusopathy (6/88 = 6.8%), hepatitis C (6/88 = 6.8%), and hepatitis B (6/88 = 6.8%). CONCLUSIONS: Coinfections may be involved in the development and maintenance of leprosy reactions.

Plasma levels of complement proteins from the alternative pathway in patients with age-related macular degeneration are independent of Complement Factor H Tyr(402)His polymorphism

Purpose: To investigate the influence of the Factor H (CFH) Tyr(402)His polymorphism on the plasma levels of the alternative pathway proteins CFH, C3, Factor B (FB), Factor D (FD), and Factor I (FI) and the inflammatory marker C-reactive protein (CRP) in 119 patients with age-related macular degeneration (AMD) and 152 unrelated control individuals. Methods: Patients with AMD and the control group were separated according to CFH polymorphism, age, and gender. Plasma complement proteins and CRP concentrations were determined with enzyme-linked immunosorbent assay, immunodiffusion, or nephelometry. Results: Significant differences in the concentrations of FD and FI were observed between the patients with AMD and the control individuals. We observed significantly reduced FD plasma levels in patients with AMD. We also identified a significant decrease in CFH plasma levels in female patients with AMD in relation to female controls. Plasma FI levels were significantly increased in patients with AMD compared to the control group. Regarding gender, a significant increase in FI plasma levels was observed in male patients. Finally, we found no significant correlation between the CFH Tyr(402)His polymorphism and the CFH, C3, FB, FD, FI, and CRP plasma levels. Conclusions: Patients with AMD present altered levels of FD and FI in a manner independent of this CFH polymorphism, and gender apparently contributes to the plasma levels of these two proteins in patients with AMD and control individuals.

The density of metastatic lymph node as prognostic factor in squamous cell carcinoma of the tongue and floor of the mouth

The presence of metastatic lymph nodes is a relevant prognostic factor in oral cancer. Objective: This paper aims to assess metastatic lymph node density (pN+) in patients with tongue and floor-of-mouth squamous cell carcinoma (SCC) and the association of this parameter with disease-free survival (DFS). Materials and Methods: A group of 182 patients seen between 1985 and 2007 was included, 169 of which were males. Five were on stage I, 35 on stage II, 56 on stage III, and 85 on stage IV. Median values were considered in lymph node density assessment, and the Kaplan-Meier curve was used to evaluate DFS; survival differences within the group were elicited through the log-rank test. Results: An average 3.2 metastatic lymph nodes were excised from the patients in the group. Density ranged from 0.009 to 0.4, with a mean value of 0.09. Five-year DFS rates were of 44% and 28% for the groups with lymph node densities below and above the median respectively (p = 0.006). Two-year local/regional control was achieved for 71% and 49% for the patients below and above the median density respectively (p = 0.01). In terms of pN staging, local/regional control was achieved in 70% and 54% of pN1 and pN2 patients respectively, albeit without statistical significance (0.20%). Conclusion: Lymph node density may be used as a prognostic indicator for tongue and floor-ofmouth SCC.

Antiphospholipid syndrome plus rheumatic fever: a higher risk factor for stroke?

To compare clinical and laboratory findings between patients with primary antiphospholipid syndrome (PAPS) versus secondary APS due to rheumatic fever (APS-RF) (according to Jones criteria). Seventy-three APS patients (Sapporo criteria) were enrolled, and demographic, clinical, and laboratory data were collected. Exclusion criteria were heart congenital abnormalities and previous infectious endocarditis. Patients were divided into two groups: PAPS (n = 68) and APS-RF (n = 5). The mean current age, disease duration, frequencies of female gender, and Caucasian race were similar in APS-RF and PAPS patients (P > 0.05). Remarkably, the frequency of stroke was significantly higher in APS-RF compared to PAPS patients (80% vs. 25%, P = 0.02). Of note, echocardiogram of these patients did not show intracardiac thrombus. No significant differences were found in peripheral thromboembolic events (P = 1.0), pulmonary thromboembolism (P = 1.0), miscarriage (P = 0.16), thrombocytopenia (P = 0.36), arterial events (P = 0.58), and thrombosis of small vessels (P = 1.0). There were no differences in the frequencies of comorbidities such as diabetes mellitus, hypertension, smoking, and hyperlipidemia in both groups (P > 0.05). The frequencies of lupus anticoagulant, IgG, and IgM anticardiolipin were similar in two groups. APS patients associated with rheumatic fever without infective endocarditis may imply a high stroke risk as compared with PAPS, and future studies are needed to confirm this finding.

Redescriptions of two species and descriptions of three new species of the louse genus Bizarrifrons Eichler, 1938 (Phthiraptera: Ischnocera: Philopteridae)

Redescriptions of Bizarrifrons magus (Nitzsch [in Giebel], 1866), the type species of Bizarrifrons, and B. picturatus Carriker & Diaz-Ungria, 1961 are given based on material from their type hosts. The nymphal instars of these two species are described and illustrated for the first time. Also, three new species are named and described: B. latifrons, from the russet-backed oropendola, Psarocolius angustifrons alfredi (Des Murs, 1856); B. wecksteini, from the Amazonian oropendola, Psarocolius b. bifasciatus (Spix, 1824); and B. quasisymmetricus, from the solitary cacique, Cacicus solitarius (Vieillot, 1816) (Passeriformes: Icteridae). Two species-groups are proposed, and a checklist and a key for the species of Bizarrifrons are also included. Sequences of a portion of the mitochondrial cytochrome oxidase I (COI) and the nuclear elongation factor 1 alpha (EF-1 alpha) genes for two species are given for the first time in this genus.

Polymorphisms in antithrombin and in tissue factor pathway inhibitor genes are associated with recurrent pregnancy loss

Recurrent pregnancy loss (RPL) is a multifactorial condition. The effect of antithrombin (SERPINC1), protein C (PROC), thrombomodulin (THBD) and tissue factor pathway inhibitor (TFPI) single nucleotide polymorphisms (SNPs) on the risk of RPL is thus far unknown. Our objective was to determine the association of SNPs in the above mentioned genes with RPL. We included 117 non-pregnant women with three or more consecutive losses prior to 20 weeks of pregnancy without a previous history of carrying a fetus to viability, and 264 healthy fertile non-pregnant women who had at least two term deliveries and no known pregnancy losses. The PROC (rs1799809 and rs1799808), SERPINC1 (rs2227589), THBD (rs1042579) and TFPI (rs10931292, rs8176592 and rs10153820) SNPs were analysed by Real Time PCR. Genotype frequencies for PROC 2418A > G, PROC 2405C > T, THBD 1418C > T, TFPI (T-33C and TFPI C-399T) SNPs were similar in cases and controls. The carriers of SERPINC1 786A allele (GA + AA genotypes) had an increased risk for RPL (odds ratio [OR]: 1.77, 95% confidence interval [CI]: 1.05-3.00, p=0.034) while women carrying the TFPI-287C allele (TC + CC genotypes) had a protection effect on having RPL (OR: 0.46, 95% CI: 0.26 - 0.83, p=0.009). The TCC haplotype for TFPI T-33C/TFPI T-287C/TFPI C-399T SNPs was less frequent in cases (5.7%) than in controls (11.6%) (OR: 0.45, 95% CI: 0.23 - 0.90, p=0.025). In conclusion, our data indicate that SERPINC1 786G > A variant increases the risk for RPL, while TFPI T-287C variant is protective; however, further studies are required to confirm our findings.

Transforming growth factor alpha immunoreactivity. A study in hepatocellular carcinoma and in non-neoplastic liver tissue

Background. Transforming growth factor alpha (TGF alpha) is an important mitogen that binds to epidermal growth factor receptor and is associated with the development of several tumors. Aims. Assessment of the immunoexpression of TGF alpha in hepatocellular carcinoma (HCC) and in non-neoplastic liver tissue and its relationship to morphological patterns of HCC. Material and methods. The immunohistochemical expression of TGF alpha was studied in 47 cases of HCC (27 multinodular, 20 nodular lesions). Five lesions measured up to 5 cm and 15 lesions above 5 cm. Thirty-two cases were graded as I or II and 15 as III or IV. The non-neoplastic tissue was examined in 40 cases, of which 22 had cirrhosis. HBsAg and anti-HCV were positive in 5/38 and 15/37 patients, respectively. The statistical analysis for possible association of immunostaining of TGF alpha and pathological features was performed through chi-square test. Results. TGF alpha was detected in 31.9% of the HCC and in 42.5% of the non-neoplastic. There was a statistically significant association between the expression of TGF alpha and cirrhosis (OR = 8.75, 95% CI = [1.93, 39.75]). The TGF alpha was detected more frequently in patients anti-HCV(+) than in those HBsAg(+). The immunoexpression of TGF alpha was not found related to tumor size or differentiation. In conclusion the TGF alpha is present in hepatocarcinogenesis in HBV negative patients. Further analysis is needed to examine the involvement of TGF alpha in the carcinogenesis associated with HCV and other possible agents. In addition, TGF alpha has an higher expression in hepatocyte regeneration and proliferation in cirrhotic livers than in HCC.

Plasma corticosterone elevation inhibits the activation of nuclear factor kappa B (NFKB) in the Syrian hamster pineal gland

We evaluated how the mild stress-induced increase in endogenous corticosterone affected the pineal gland in Syrian hamsters (Mesocricetus auratus). The animals were maintained under constant light for 1 day, instead of a cycle of 14:10-h, to increase the circulating corticosterone levels during the daytime. The nuclear translocation of nuclear factor kappa B (NFKB), which is the pivotal transcription factor for stress and injury, presented a daily rhythm in normal animals. NFKB nuclear content increased linearly from the onset of light [Zeitgeber Time 0 (ZT0)] until ZT11 and decreased after ZT12 when the plasma corticosterone peak was detected in normal animals. However, the 24-h profiles of the two curves were different, and they did not clearly support an exclusive relationship between corticosterone levels and NFKB content. Therefore, we tested the effect of increased endogenous corticosterone through inducing mild stress by maintaining daytime illumination for one night. This stressful condition, which increased daytime corticosterone levels, resulted in a daytime decrease in NFKB nuclear content, and this was inhibited by mifepristone. Overall, this study shows that NFKB has a daily rhythm in Syrian hamster pineal glands and, by increasing endogenous corticosterone with a stressful condition, NFKB activity is regulated. Therefore, this study suggests that the pineal gland in the Syrian hamster is a sensor of stressful conditions.

Partitioning and extraction of collagenase from Penicillium aurantiogriseum in poly(ethylene glycol)/phosphate aqueous two-phase system

Purification of collagenase produced by Penicillium aurantiogriseum URM4622 was carried using a PEG/phosphate aqueous two-phase system (ATPS). A 2(3)-full experimental design was used to investigate the influence of PEG molar mass, PEG concentration and phosphate concentration on the selected responses, namely partition coefficient, activity yield and purification factor. The ATPS was composed of PEG (molar mass of 550, 1500 and 4000 g/mol) at concentrations of 15.0, 17.5 and 20.0% (w/w) and phosphate at concentrations of 12.5, 15.0 and 17.5% (w/w). The best results of one-step extraction of collagenase from the fermentation broth (partition coefficient of 1.01, activity yield of 242% and purification factor of 23.5) were obtained at pH 6.0 using 20.0% (w/w) PEG 550 and 17.5% (w/w) phosphate. The results of this preliminary study demonstrate that the selected ATPS is satisfactorily selective for the extraction of such a collagenase. (C) 2012 Elsevier B.V. All rights reserved.

IRF6 is a Risk Factor for Nonsyndromic Cleft Lip in the Brazilian Population

Nonsyndromic cleft lip with or without cleft palate (NSCL/P) is a complex disorder with a worldwide incidence estimated at 1:700. Among the putative susceptibility loci, the IRF6 gene and a region at 8q24.21 have been corroborated in different populations. To test the role of IRF6 in NSCL/P predisposition in the Brazilian population, we conducted a structured association study with the SNPs rs642961 and rs590223, respectively, located at 5' and 3' of the IRF6 gene and not in strong linkage disequilibrium (LD), in patients from five different Brazilian locations. We also evaluated the effect of these SNPs in IRF6 expression in mesenchymal stem cells (MSC). We observed association between rs642961 and cleft lip only (CLO) (P = 0.009; odds ratio (OR) for AA genotype = 1.83 [95% Confidence interval (CI), 0.64-5.31]; OR for AG genotype = 1.72 [95% CI, 1.03-2.84]). This association seems to be driven by the affected patients from Barbalha, a location which presents the highest heritability estimate (H-2 = 0.85), and the A allele at rs642961 is acting through a dominant model. No association was detected for the SNP rs590223. We did not find any correlation between expression levels and genotypes of the two loci, and it is possible that these SNPs have a functional role in some specific period of embryogenesis. (C) 2012 Wiley Periodicals, Inc.

Extracytoplasmic function (ECF) sigma factor sigma(F) is involved in Caulobacter crescentus response to heavy metal stress

Background: The alpha-proteobacterium Caulobacter crescentus inhabits low-nutrient environments and can tolerate certain levels of heavy metals in these sites. It has been reported that C. crescentus responds to exposure to various heavy metals by altering the expression of a large number of genes. Results: In this work, we show that the ECF sigma factor sigma(F) is one of the regulatory proteins involved in the control of the transcriptional response to chromium and cadmium. Microarray experiments indicate that sigma(F) controls eight genes during chromium stress, most of which were previously described as induced by heavy metals. Surprisingly, sigma(F) itself is not strongly auto-regulated under metal stress conditions. Interestingly, sigma(F)-dependent genes are not induced in the presence of agents that generate reactive oxygen species. Promoter analyses revealed that a conserved sigma(F)-dependent sequence is located upstream of all genes of the sigma(F) regulon. In addition, we show that the second gene in the sigF operon acts as a negative regulator of sigma(F) function, and the encoded protein has been named NrsF (Negative regulator of sigma F). Substitution of two conserved cysteine residues (C131 and C181) in NrsF affects its ability to maintain the expression of sigma(F)-dependent genes at basal levels. Furthermore, we show that sigma(F) is released into the cytoplasm during chromium stress and in cells carrying point mutations in both conserved cysteines of the protein NrsF. Conclusion: A possible mechanism for induction of the sigma(F)-dependent genes by chromium and cadmium is the inactivation of the putative anti-sigma factor NrsF, leading to the release of sigma(F) to bind RNA polymerase core and drive transcription of its regulon.

Possible Host Adaptation as an Evolution Factor of Cowpea aphid-borne mosaic virus Deduced by Coat Protein Gene Analysis

Cowpea aphid-borne mosaic virus (CABMV) causes major diseases in cowpea and passion flower plants in Brazil and also in other countries. CABMV has also been isolated from leguminous species including, Cassia hoffmannseggii, Canavalia rosea, Crotalaria juncea and Arachis hypogaea in Brazil. The virus seems to be adapted to two distinct families, the Passifloraceae and Fabaceae. Aiming to identify CABMV and elucidate a possible host adaptation of this virus species, isolates from cowpea, passion flower and C.hoffmannseggii collected in the states of Pernambuco and Rio Grande do Norte were analysed by sequencing the complete coat protein genes. A phylogenetic tree was constructed based on the obtained sequences and those available in public databases. Major Brazilian isolates from passion flower, independently of the geographical distances among them, were grouped in three different clusters. The possible host adaptation was also observed in fabaceous-infecting CABMV Brazilian isolates. These host adaptations possibly occurred independently within Brazil, so all these clusters belong to a bigger Brazilian cluster. Nevertheless, African passion flower or cowpea-infecting isolates formed totally different clusters. These results showed that host adaptation could be one factor for CABMV evolution, although geographical isolation is a stronger factor.