Instability and translocation through nanopores of DNA interacting with single-layer materials

In this study, we use classical applied mathematical modelling to employ the 6–12 Lennard-Jones potential function along with the continuous approximation to investigate the interaction energies between a double-stranded deoxyribonucleic acid (dsDNA) molecule and two-dimensional nanomaterials, namely graphene (GRA), hexagonal boron nitride (h-BN), molybdenum disulphide (MoS₂), and tungsten disulphide (WS₂). Assuming that the dsDNA molecule has a perpendicular distance Δ above the nano-sheet surface, we calculated the molecular interaction energy and determined the relation between the location of the minimum energy and Δ. We also investigated the interaction of a dsDNA molecule with the surface of each nano-sheet in the presence of a circular hole simulating a nanopore. The radius of the nanopore that results in the minimum energy was determined. Our results show that the adsorption energies of the dsDNA molecule with GRA, h-BN, MoS₂, and WS₂ nano-sheets corresponding to the perpendicular distance Δ = 20 Å are approximately 70, 82, 28, and 26 (kcal mol⁻¹), respectively, and we observed that the dsDNA molecule moves through nanopores of radii greater than 12.2 Å.

Using classical applied mathematical modelling to employ the 6–12 Lennard-Jones potential function along with the continuous approximation to investigate the interaction energy between dsDNA and 2D-nanomaterials, namely GRA, h-BN, MoS₂ and WS₂ sheets.     

Evidence of frontotemporal structural hypoconnectivity in social anxiety disorder: A quantitative fiber tractography study

Investigation of the brain's white matter fiber tracts in social anxiety disorder (SAD) may provide insight into the underlying pathophysiology. Because models of pathological anxiety posit altered frontolimbic interactions, the uncinate fasciculus (UF) connecting (orbito‐) frontal and temporal areas including the amygdala is of particular interest. Microstructural alterations in parts of the UF have been reported previously, whereas examination of the UF as discrete fiber tract with regard to more large‐scale properties is still lacking. Diffusion tensor imaging was applied in 25 patients with generalized SAD and 25 healthy control subjects matched by age and gender. By means of fiber tractography, the UF was reconstructed for each participant. The inferior fronto‐occipital fasciculus (IFOF), originating from the frontal cortex similarly to the UF, was additionally included as control tract. Volume and fractional anisotropy (FA) were compared between the groups for both tracts. Volume of left and right UF was reduced in patients with SAD, reaching statistical significance for the left UF. Bilateral IFOF volume was not different between groups. A similar pattern was observed for FA. Reduced volume of the left UF in SAD fits well into pathophysiological models of anxiety, as it suggests deficient structural connectivity between higher‐level control areas in the orbitofrontal cortex and more basal limbic areas like the amygdala. The results point to a specific role of the left UF with regard to altered white matter volume in SAD. However, results should be replicated and functional correlates of altered UF volume be determined in future studies. Hum Brain Mapp, 2013. © 2011 Wiley Periodicals, Inc.     

Antibodies to proteinase-3 and myeloperoxidase in systemic vasculitis

AIM: To investigate occurrence and diagnostic significance of antibodies to proteinase-3 (aPR-3) and myeloperoxidase (aMPO) in systemic vasculitis (SV). MATERIAL AND METHODS: A total of 98 patients with different forms of SV were examined: nonspecific aortoarteritis (NAA, n = 18), nodular polyarteritis (NP, n = 18), Wegener granulomatosis (WG, n = 20), obliterating thrombangiitis (OT, n = 21), and hemorrhagic vasculitis (HV, n = 21). Eight patients with primary antiphospholipid syndrome (PAPS) and 20 donors comprised a control group. aPR-3 and aMPO were detected by solid-phase enzyme immunoassay using kits ORGenTec Diagnostica GmbH. RESULTS: aPR-3 were detected in 1 (5.6%) patient with NP and in 3 (14.3%) patients with HV. aPR-3 were detected in 13 (65%) of 20 patients with WG being significantly more frequent not only vs controls (0%) but in some forms of SV and PAPS (p < 0.05). Mean aPR-3 level in 13 WG patients was significantly higher than in 4 patients (1 with NP and 3 with HV) the sera of whom also contained aPR-3. 84.6% patients with WG had higher concentrations of aPR-3, this is significantly more frequently than in the comparison group. In NP and HV these autoantibodies were encountered in the serum only in moderate or low concentrations in patients with high clinicolaboratory activity of the disease. In WG patients there was no correlation between aPR-3 presence, form of the disease and basic clinical manifestations, but mean values of index of clinical activity of vasculitis were significantly higher in patients with aPR-3 than in those free of them. Concentration of aPR-3 in an active phase of the disease was significantly higher than in patients in remission. Moreover, aPR-3 were detected in 83.3% cases in active vasculitis and in 37.5% patients without it. Detection of aPR-3 in WG group was associated with mean sensitivity and good specificity. In examination of the patients in an active phase specificity rose but sensitivity fell. Optimal results were obtained in estimation of aPR-3 level. Thus, in moderate or high concentration, aPR-3 have good sensitivity and high specificity for diagnosis of WG, in a high titer (> 15 U/ml) they are highly sensitive and specific for this vasculitis. aMPO were detected in 1 of 18 patients with NP, in 1 of 21--with OT, in 3 of 21--with HV and in 2 of 21--with NAA. None patients with WG or PAPS had aMPO. aMPO were detected in NP and HV in high activity of inflammation. Part of the patients had affected kidneys. CONCLUSION: Thus, WG is characterized by the presence and high concentration of aPR-3. In the latter case aPR-3 have high (100%) sensitivity and specificity for diagnosis of WG. Detection of aPR-3 can be used as an additional laboratory test for diagnosis of WG and estimation of its activity.     

High Prevalence of HBsAg during Pregnancy in Asian Communities at Cayenne Hospital,French Guiana

We described hepatitis B surface antigen (HBsAg) prevalence among 2,347 pregnant women having delivered at the Cayenne hospital in 2007 according to ethnicity. With 11.0% HBsAg prevalence, Asian women (Hmong and Chinese) were the group with the highest risk of hepatitis B virus (HBV) perinatal transmission compared with other ethnic groups.An estimated 2 billion people have been infected with the hepatitis B virus (HBV) worldwide and between 350 and 400 million persons have chronic liver infections with the presence of hepatitis B surface antigen (HBsAg).¹ Low, intermediate, and high HBV endemicity areas are defined as prevalence of HBsAg in the general population < 2%, between 2% and 8%, and > 8%, respectively. Western Europe and North America have low endemicity, whereas the Middle East and Indian subcontinent have an intermediate endemicity. China and other parts of Asia, Eastern and Central Europe, much of Africa, and the Amazon Basin are high endemicity areas.² French Guiana is an overseas French region located in the Amazon Basin on the northeast coast of the South American continent between Brazil and Suriname. The HBsAg prevalence is unknown in the population of French Guiana (200,000 inhabitants), which is a melting pot of a large variety of ethnic groups, including Creoles (mixed European and African descent), Amerindians, Maroons (African descent), Caucasians (from metropolitan France), and immigrants from Haiti, Suriname, Brazil, and Asian countries (Hmong and Chinese). In high endemic areas, HBV infection occurs during infancy and early childhood by either horizontal or perinatal transmission by pregnant women carrying HBsAg who act as a reservoir for HBV.³ Nevertheless, more than 90% of perinatal infections can be prevented if HBsAg-positive mothers are identified and their newborns are treated promptly after delivery with hepatitis B (HB) immune globuline and HB vaccine. To improve prevention campaigns in high endemic areas, there is a need to identify groups with high risk of HBV perinatal transmission. Our objective was, therefore, to estimate the prevalence of HBsAg during pregnancy in the various ethnic groups of French Guiana. We conducted a retrospective study of HBsAg prevalence among all pregnancies delivered in the obstetric unit of the Cayenne hospital from January 1 to December 31, 2007. Data on maternal variables (age, ethnicity, cesarean delivery, and residence site) and newborn vaccination status were collected in the registre d''issue des grossesses, which has clearance from the Commission Nationale Informatique et Libertes. All pregnant women were tested for HBsAg (Axsym HBsAg v2.0; Abbott Diagnostics, Wiesbaden, Germany).The mean age of the 2,347 women included and screened for HBsAg was 27.4 ± 7 years (range = 11–47 years). There were Asians (2.1%; N = 46), metropolitans (3.3%; N = 76), Amerindians (5.9%; N = 132), Maroons (15.2%; N = 342), Brazilians (15.6%; N = 351), Creoles (19.9%; N = 448), and Haitians (22.9%; N = 517). The ethnicity was undetermined for 14.9% of women. Nearly one-half (49%) of them lived in Cayenne, and the others lived throughout French Guiana. The overall prevalence of HBsAg positivity was 1.5% (95% confidence interval [CI] = 1.1–2.1) and varied according to ethnicities. The prevalence was higher in Asian women (Hmong and Chinese) at 11.0% (95% CI = 4.1–22.4) and lower in Amerindians at 0.8% (95% CI = 0.1–3.6) and Brazilians or Caucasians at 0.3% each (95% CI = 0.1–1.4; P < 0.0001). It was 2.3% (95% CI = 1.1–4.4) and 1.9% (95% CI = 1.0–2.7) in Maroon and Creole women, respectively (Figure 1). There was no association between prevalence of HBsAg and residence or age (P > 0.05). There was no significant difference in HBsAg prevalence among women delivering vaginally (1.6%) and by caesarean (1.1%).Open in a separate windowFigure 1.HBV areas of endemicity in French Guiana according to HBsAg prevalence in pregnant women.

Table 1

Prevalence of HBsAg carriage according to ethnicity

Distribution of scales containing NORM in different oilfields equipment.

Evaluation has been made of the distribution of hard scales containing naturally occurring radioactive materials (NORM) in a range of oilfield equipment in Syrian oilfields. One hundred and fifty-two scale samples from oilfield equipment were collected and analysed for radioactivity, elemental and mineralogical compositions. The average 226Ra, 228Ra and 224Ra concentrations in scales were found to be 174, 91 and 67 Bqg(-1), respectively; the highest value of 226Ra was found to be 1520 Bqg(-1). A gradual increase in 226Ra specific activity from down-hole tubulars to surface parts of the installations was observed. The 228Ra/226Ra mean activity ratio was observed to be 0.76, indicating a Th/U mass ratio of about 2.3. This value can be considered a fingerprint for the Th/U mass ratio of the geological formation of the reservoir. Radium isotopic data were also used to estimate the age of the deposited scales using the 224Ra/228Ra activity ratio; the highest average age (5.3 years) was found to be in scales collected from valves. Multiple regressions of the data have shown that 226Ra is more highly correlated with Ba and Sr content in scales (R2=0.92) than Ca. Around 77% of 226Ra was found to be incorporated with anhydrate barium strontium sulphate (R2=0.93), solubility in water being very low to negligible; lower levels of radium isotopes were found in calcite.     

White matter alterations in social anxiety disorder

White matter architecture in patients with social anxiety disorder (SAD) has rarely been investigated, but may yield insights with respect to altered structural brain connectivity. Initial evidence points to alterations in the uncinate fasciculus (UF). We applied diffusion tensor imaging in 25 patients with SAD and 25 matched healthy subjects. Whole-brain fractional anisotropy (FA) maps were used for group comparison and voxel-wise correlation with psychometric and clinical measures. Additionally, a region-of-interest analysis of the UF was performed. Patients with SAD had reduced FA compared to healthy subjects in or near the left UF and the left superior longitudinal fasciculus. There were no regions with increased FA in SAD. In the region-of-interest analysis, a negative correlation between FA and trait anxiety was identified in the left and right UF in patients, but not in healthy subjects. No correlations with social anxiety scores were observed. The present study partially confirms previous results pointing to frontal WM alterations in or near the UF in patients with SAD. SAD-specific dimensional associations of FA with trait anxiety might reflect general pathological and/or compensatory mechanisms as a function of symptom severity in patients. Future studies should disentangle in which way the identified WM alterations match functional alterations.