Reversal of atomic contrast in scanning probe microscopy on (111) metal surfaces

We study the origin of atomic contrast on Cu(111) and Pt(111) surfaces probed by a non-contact atomic force microscope and scanning tunnelling microscope. First-principles simulations of the interaction between the atoms of the scanning tip and those of the probed surface show a dependence of the resulting contrast on the tip-sample distance and reveal a close relation between contrast changes and relaxation of atomic positions in both the tip and the sample. Contrast reversion around the distance where the short-range attractive atomic force reaches its maximum is predicted for both types of microscopies. We also demonstrate a relation between the maximal attractive force in a F-z atomic force spectroscopy and the chemical identity of the apex atom on the imaging tip.

Effects of oestradiol on brain lipid class and Fatty Acid composition: comparison between pregnant and ovariectomised oestradiol-treated rats

To determine the involvement of physiological doses of oestradiol on brain lipid composition, we have analysed the lipid class and fatty acid composition of phospholipids in the brain from pregnant and 17β-oestradiol-treated rats. Rats were randomly divided into three groups: ovariectomised control (OVX + VEH), ovariectomised oestradiol-treated (OVX + E(2) ) and pregnant (PREG) rats. Rats from the OVX + E(2) group were injected daily with different doses of 17β-oestradiol mimicking the plasma levels observed during pregnancy. Analyses of brain lipid class composition showed that physiological doses of oestradiol increased cholesterol levels of the OVX + E(2) group compared to the OVX + VEH group. It was also found that cholesterol levels in the PREG group were significantly lower than in the OVX + VEH and OVX + E(2) groups, indicating the involvement of gestational hormones other than oestradiol in the regulation of brain cholesterol during pregnancy. Brains from pregnant rats also exhibited reduced levels of plasmalogens and saturated fatty acids compared to the ovariectomised groups, especially in the second half of pregnancy. Interestingly, analyses of fatty acid composition of phospholipids revealed that physiological doses of oestradiol increased brain docosahexaenoic acid (DHA; 22:6 n-3) levels. Moreover, DHA levels in pregnant rats were similar to those observed in the OVX + E(2) group at all stages, suggesting that oestradiol is the main hormone in the regulation of brain DHA levels during pregnancy. Liver appears to be the major source for n-3 and n-6 long chain polyunsaturated fatty acids (LCPUFAs) DHA and arachidonic acid, which are released and transported to the maternal brain and the developing foetus under the influence of oestrogens. We also observed that the largest depots of n-3 and n-6 LCPUFA precursors (linolenic acid and linoleic acid, respectively) occur in adipose tissue triglycerides, which, in turn are significantly increased during pregnancy. Our observations are in accordance with an oestradiol-induced increased bioavailability of brain DHA in pregnant rats. We hypothesise that the reduction of maternal brain DHA observed at the end of pregnancy is a result of the very high demand DHA of foetal brain, which overcomes the maximal maternal (and likely foetal) capacity for de novo DHA synthesis in the liver and brain.

Geographical structuring of Trypanosoma cruzi populations from Chilean Triatoma infestans triatomines and their genetic relationship with other Latino American counterparts

In order to obtain more information about the population structure of Chilean Trypanosoma cruzi, and their genetic relationship with other Latino American counterparts, we performed the study of T. cruzi samples detected in the midgut content of Triatoma infestans insects from three endemic regions of Chile. The genetic characteristics of these samples were analysed using microsatellite markers and PCR conditions that allow the detection of predominant T. cruzi clones directly in triatomine midgut content. Population genetic analyses using the Fisher's exact method, analysis of molecular variance (AMOVA) and the determination of F(ST) showed that the northern T. cruzi population sample was genetically differentiated from the two southern population counterparts. Further analysis showed that the cause of this genetic differentiation was the asymmetrical distribution of TcIII T. cruzi predominant clones. Considering all triatomines from the three regions, the most frequent predominant lineages were TcIII (38%), followed by TcI (34%) and hybrid (8%). No TcII lineage was observed along the predominant T. cruzi clones. The best phylogenetic reconstruction using the shared allelic genetic distance was concordant with the population genetic analysis and tree topology previously described studying foreign samples. The correlation studies showed that the lineage TcIII from the III region was genetically differentiated from the other two, and this differentiation was correlated with geographical distance including Chilean and mainly Brazilian samples. It will be interesting to investigate whether this geographical structure may be related with different clinical manifestation of Chagas disease.

Multiscale modeling of composite materials: a roadmap towards virtual testing

A bottom-up, multiscale modeling approach is presented to carry out high-fidelity virtual mechanical tests of composite materials and structures. The strategy begins with the in situ measurement of the matrix and interface mechanical properties at the nanometer-micrometer range to build up a ladder of the numerical simulations, which take into account the relevant deformation and failure mechanisms at different length scales relevant to individual plies, laminates and components. The main features of each simulation step and the information transferred between length scales are described in detail as well as the current limitations and the areas for further development. Finally, the roadmap for the extension of the current strategy to include functional properties and processing into the simulation scheme is delineated.

Effects of cigarette smoke and hypoxia on pulmonary circulation in the guinea pig

Cigarette smoke (CS) and chronic hypoxia (CH) can produce pulmonary hypertension. Similarities and differences between both exposures and their interaction have not been explored. The aim of the present study was to investigate the effects of CS and CH, as single factors or in combination, on the pulmonary circulation in the guinea pig. 51 guinea pigs were exposed to CS for 12 weeks and 32 were sham-exposed. 50% of the animals in each group were additionally exposed to CH for the final 2 weeks. We measured pulmonary artery pressure (P(pa)), and the weight ratio between the right ventricle (RV) and left ventricle plus the septum. Pulmonary artery contractility in response to noradrenaline (NA), endothelium-dependent vasodilatation and distensibility were evaluated in organ bath chambers. The number of small intrapulmonary vessels showing immunoreactivity to smooth muscle (SM) α-actin and double elastic laminas was assessed microscopically. CS and CH induced similar increases of P(pa) and RV hypertrophy (p<0.05 for both), effects that were further enhanced when both factors were combined. CH increased the contractility to NA (p<0.01) and reduced the distensibility (p<0.05) of pulmonary arteries. Animals exposed to CS showed an increased number of small vessels with positive immunoreactivity to SM α-actin (p<0.01) and those exposed to CH a greater proportion of vessels with double elastic laminas (p<0.05). We conclude that CH amplifies the detrimental effects of CS on the pulmonary circulation by altering the mechanical properties of pulmonary arteries and enhancing the remodelling of pulmonary arterioles.

Use of axillary ultrasound, ultrasound-fine needle aspiration biopsy and magnetic resonance imaging in the preoperative triage of breast cancer patients considered for sentinel node biopsy

We assessed the diagnostic yield of axillary ultrasound, alone or in combination with fine-needle aspiration axillary biopsy and magnetic resonance imaging in patients with invasive breast carcinoma compared with final axillary histology by sentinel node biopsy or by axillary lymph node dissection. From January 2003 to March 2009, 520 axillary ultrasound examinations and 105 axillary magnetic resonance imaging studies were included. Compared with final axillary histology, ultrasound fine-needle aspiration showed positive predictive value of 87%, negative predictive value of 82%, sensitivity of 53% and specificity of 100%. In cases of negative ultrasound, the rate of positive nodes was 17% (micro-metastases excluded). Ultrasound examination of the axilla, combined with fine-needle aspiration as appropriate must be included in the preoperative work-up of patients considered for sentinel node biopsy to definitively establish such an indication while minimizing the risk of false-negative sentinel node. Axillary magnetic resonance imaging did not improve the preoperative work-up.

Ordered vacancy network induced by the growth of epitaxial graphene on Pt(111)

We have studied large areas of (√3×√3)R30° graphene commensurate with a Pt(111) substrate. A combination of experimental techniques with ab initio density functional theory indicates that this structure is related to a reconstruction at the Pt surface, consisting of an ordered vacancy network formed in the outermost Pt layer and a graphene layer covalently bound to the Pt substrate. The formation of this reconstruction is enhanced if low temperatures and polycyclic aromatic hydrocarbons are used as molecular precursors for epitaxial growth of the graphene layers.

Fibromyalgia in patients with ankylosing spondylitis: prevalence and utility of the measures of activity, function and radiological damage

OBJECTIVES

To determine the prevalence of fibromyalgia (FM) in ankylosing spondylitis (AS). To evaluate the effect of FM on the measures of activity in AS. To analyse predictive factors in order to identify this group of patients.

PATIENTS AND METHODS

A cross-sectional study based on 462 patients with definite ankylosing spondylitis included in the REGISPONSER. Sociodemographic data, clinical features, Bath AS disease activity index (BASDAI), Bath AS functional index (BASFI), Bath AS radiology index (BASRI), Stoke modified index (Sasss-m), laboratory data, Short-Format 12 (SF-12), AS specific quality of life (ASQoL), Fibromyalgia Impact Questionnaire (FIQ) and treatments used were all documented. To diagnose FM, the ACR 1990 criteria had to be fulfilled. All statistical tests were performed using STATA.

RESULTS

The prevalence of fibromyalgia in all AS was 4.11%. Among the women with AS, the prevalence of FM increased to 10.83%. The BASDAI, BASFI and total BASRI were strongly influenced by the presence of FM. The inverse relationship between BASDAI or BASFI and total BASRI was taken to generate a ratio. Accordingly, if the patient presented BASDAI/BASRI ≥1.5 or BASFI/BASRI ≥1.08, the probability of having FM was very high.

CONCLUSIONS

There is an increased risk of FM in females with AS. The fact of having FM distorts the measures of activity and functional damage of AS. As a result, it is possible that some patients with AS and FM are being overtreated. The BASDAI/BASRI and BASFI/BASRI ratios are very useful to identify these patients.

Acute oral, pulmonary and intravenous toxicity/pathogenicity testing of a new formulation of Bacillus thuringiensis var israelensis SH-14 in rats

During the last decades, efforts are being made to develop microbial insecticides as biological control agents. Bacillus thuringiensis has been one of the most consistent and significant biopesticides for using on crops as an insecticidal spray. The aim of this study was to assess and to compare the pathogenicity of a new formulation of B.thuringiensis var israelensis SH-14 in rats through oral, intranasal and intravenous single dosing. Through 21 days after administration, clinical examinations were performed daily, and body weight gain was evaluated. Clearance was estimated by means of collection of feces or examination of lungs and blood, and infectivity was evaluated enumerating microorganisms from organs of Bti SH-14 treated animals sacrificed at intervals. Gross necropsy of animals was performed at interim or final sacrifice. There were no treatment-related mortalities, and no evidence of pathogenicity or treatment related toxicity, although in the intravenous study, the microorganism was capable of achieving persistence in organs after administration, and the Bti SH-14 treated animals developed skin ulcerations and hemorrhages at the injection site. It could be concluded that the tested microorganism was not toxic or pathogenic to rats via oral or intranasal route, although it was capable of achieving persistence in organs after intravenous administration, eliciting local effects at the injection site.

Understanding atomic-resolved STM images on TiO2(110)-(1 x 1) surface by DFT calculations

We present a combination of experimental STM images and DFT calculations to understand the atomic scale contrast of features found in high-resolution STM images. Simulating different plausible structural models for the tip, we have been able to reproduce various characteristics previously reported in experimental images on TiO(2)(110)-(1 x 1) under controlled UHV conditions. Our results allow us to determine the influence of different chemical and morphological tip terminations on the atomic-resolution STM images of the TiO(2)(110)-(1 x 1) surface. The commonest images have been properly explained using standard models for a W tip, either clean or with a single O atom located at the apex. Furthermore, a double transfer of oxygen atoms can account for different types of bizarre atomic-resolution features occasionally seen, and not conclusively interpreted before. Importantly, we discuss how typical point-defects are imaged on this surface by different tips, namely bridging O vacancies and adsorbed OH groups.

Chronic 17beta-estradiol treatment improves skeletal muscle insulin signaling pathway components in insulin resistance associated with aging

Insulin resistance is a common feature of aging in both humans and rats. In the case of females, it seems to be related to loss of gonadal function, due mainly due to a decrease in plasma estrogen levels. Several causes have been postulated for this insulin resistance, among them changes in several steps of the insulin pathway. In view of these findings, the purpose of the present study was to examine the role of chronic 17beta-estradiol treatment on insulin sensitivity during the aging process, and its effects on levels of the insulin-sensitive glucose transporter Glut4 (both total and plasma membrane localized), the interaction between p85alpha subunit of PI3-k and IRS-1, Tyr- and Ser-612 phosphorylation of IRS-1 levels, and Ser-473 phosphorylation of Akt. The present findings indicate that 17beta-estradiol treatment is able to minimize the deleterious effect of aging on insulin sensitivity, at least at the level of plasma membrane localized Glut4. Nevertheless further research is needed to determine this conclusively.

Training model for teaching endoscopic submucosal dissection of gastric tumors

INTRODUCTION

The elevated risk of complications and technical complexity of endoscopic submucosal dissection (ESD) has limited its implementation in our medical system.

OBJECTIVE

To design and evaluate a training program for learning the ESD technique.

METHODS

Four endoscopists with no experience with ESD underwent a 4-step training program: 1) review of the existing literature, didactic material, and theoretical aspects of ESD; 2) ESD training in an ex-vivo animal model; 3) ESD training in an in-vivo animal model (supervised by ESD expert); and 4) ESD performance in a patient. A standard gastroscope and an ESD knife (IT, Flex or Hook-knife Olympus) were employed. The classical ESD technique was performed: rising of the lesion, circumferential incision, and submucosal dissection.

RESULTS

Ex-vivo animal model: 6 x swine stomach/esophagus -cost < 100 euro; 6 x ESD: antrum (n = 2), body (n = 3) and fundus/cardia (n = 1)-; size of resected specimen: 4-10 cm; ESD duration: 105-240 minutes; therapeutic success: 100%; complications: perforation (1/6: 16%) sealed with clips. In-vivo animal model: 6 ESD (antrum/body of stomach: 4; esophagus: 2); size: 2-5 cm; duration: 40-165 minutes; success: 100%; complications: 0%.

PATIENT

ESD of a gastric lesion located in the antrum/body; size: 3 cm; duration 210 minutes; a complete resection was achieved; no complications.

CONCLUSIONS

The results of the present study support the usefulness of this model for learning ESD in our system.

Increase in placental apolipoprotein D as an adaptation to human gestational diabetes

The expression of apolipoprotein D (apo D), a lipocalin involved in defense mechanisms against oxidative stress, in placental tissue samples of pregnancies with gestational diabetes mellitus (GDM) was compared to non-diabetic controls. We have investigated the relationship of apo D with 4-HNE, a major propagation product of lipid peroxidation, in stressed tissues. We included 20 pregnant women with GDM and 30 women with normal ongoing pregnancies as the control group. Placentas were collected and frozen for Western blot or included in paraffin for immunohistochemistry. The intensity of immunostaining was higher for apo D and 4-HNE in GDM samples; however, the differences in expression between the groups was more intense for apo D. Positive signals for both antibodies was detected in the villous trophoblast and adventitia tunica around the large blood vessels for all groups. Specific immunostaining for apo D was noted in some mesenchymal and macrophagic-like cells and this signal increased in diabetic placentas. Densitometry analysis of Western blots showed no significant difference for 4-HNE, but was significantly more intense for apo D in diabetic women. The contradictory results for 4-HNE could be due to changes which are too small and are masked in tissue homogenates. The results for apo D showed a strong relationship with GDM in the placenta that may reflect its suggested function in defense mechanisms against oxidative stress.