Magnetism and perfect spin filtering effect in graphene nanoflakes

Magnetic and spin-polarized transport properties in zigzag-edged graphene nanoflakes were investigated from first-principles calculations. Ferrimagnetic structure was found to be the ground state for triangular shaped graphene flakes. Magnetism is weakened by doping B or N atoms into the flakes, and it is enhanced if F atoms are doped in certain sublattices of the flakes. The magnetic properties can be rationalized by the behaviors of dopants as well as interactions between dopants and the host atoms. A perfect (100%) spin filtering effect was achieved for the pure or B doped graphene flake sandwiched between two gold electrodes. The orientation of the spin current is found to be flipped if the flake is doped with N, O, or F atoms. The orientation-tunable spin filtering effect is potentially useful in practical applications.

Myocardial infarction and the validation of physician billing and hospitalization data using electronic medical records

OBJECTIVE

Population-based identification of patients with a myocardial infarction is limited to patients presenting to hospital with an acute event. We set out to determine if adding physician billing data to hospital discharge data would result in an accurate capture of patients who have had a myocardial infarction.

METHODS

We performed a retrospective chart abstraction of 969 randomly selected adult patients using data abstracted from primary care physicians on an electronic medical record in Ontario, Canada, as the reference standard.

RESULTS

An algorithm of 3 physician billings in a one-year period with at least one being by a specialist or within a hospital or emergency room plus one hospital discharge abstract performed with a sensitivity of 80.4% (95% CI: 69.5-91.3), specificity of 98.0% (95% CI: 97.1-98.9), positive predictive value of 69.5% (95% CI: 57.7-81.2), negative predictive value of 98.9% (95% CI: 98.2% to 99.6%) and kappa statistic of 0.73 (95% CI: 0.63-0.83).

CONCLUSION

Using a combination of hospital discharge abstracts and physician billing data may be the best way of assessing trends of MI occurrence over time since it increases the capture of MI beyond those patients who have been hospitalized.

Recombinant N-terminal part of bovine herpesvirus 1 ICP27 protein: its preparation, purification, and use for raising specific antiserum

Recombinant N-terminal part of bovine herpesvirus-1 (BoHV-1) ICP27 protein fused with thioredoxin and His-tag ("the recombinant protein") expressed in Escherichia coli was purified by the Ni2+-NTA affinity chromatography and used for the preparation of antiserum by immunization of rabbits. The antiserum recognized the recombinant protein in Western blot analysis and was able to detect BoHV-1 ICP27 in the nucleoli of BoHV-1-infected MDBK cells. These results showed that such an antiserum could serve as a valuable tool in further studies of the functions of BoHV-1 ICP27.

KEYWORDS

Bovine herpesvirus 1, ICP27, recombinant protein, antiserum, immunofluorescence assay.

Suppression effects of AICAR on insulin secretion involved in peroxisome proliferator-activated receptor gamma changes in INS-1 cells

BACKGROUND

AMP-activated protein kinase (AMPK) activation is known to attenuate glucose-stimulated insulin secretion (GSIS) in pancreatic beta cells. However, the underlying mechanisms are poorly understood. The purpose of this study was to examine the effects of AMPK activation on insulin secretion and to determine whether peroxisome proliferator-activated receptors (PPAR) are involved in the effects on INS-1 cells.

METHODS

INS-1 cells, insulinoma cell lines, were treated with an activator (AICAR) or inhibitor (Compound C) of AMPK as well as inhibitors of PPAR [MK886 and biphenol A diglycidyl ether (BADGE)] for different treatment times.

RESULTS

AICAR-induced AMPK activation significantly attenuated GSIS as well as insulin content. Meanwhile, AMPK activation increased the mRNA levels of both PPARalpha and PPARgamma. However, with regard to DNA binding, AMPK activation upregulated PPARgamma only, and it was possible to reduce the increment with the AMPK inhibitor. Moreover, the AICAR-induced suppression of insulin secretion can be counteracted by the PPARgamma inhibitor, BADGE but not the PPARalpha inhibitor.

CONCLUSIONS

AICAR-induced glucose-stimulated insulin secretion reduction correlates mainly with PPARgamma changes.

The Effect of Stem Structure on Stress Distribution of a Custom-Made Hip Prosthesis

A custom-made hip is essential for the initial stability and longevity which correspond to an optimal stress distribution, since a standard hip cannot always satisfy every patient's need. In order to find out the designing principles of a custom-made hip, a patient's personal features on which the design was based were acquired. In this study, an integrated finite element model of the hip (including ilium, acetabular cup, femoral head, femoral stem, and femur) was created based on the computed tomography (CT) images of this patient. A series model with different stem length, cross-section, and collodiaphyseal angle were analysed under both static and quasi-static loading conditions. Comparing the stress distribution on each part of the hip prosthesis with that of the natural hip before replacement, the optimal stem structure for this patient was found. In addition, the changes of interspace between acetabular cup and femoral head were measured according to dynamic CT images on the healthy side of this patient during a gait cycle. Results correspond to the trail of the maximum contact stress sites, which were mainly located on the superolateral surface of the acetabular cup. This custom-design method can also be adopted for other patients.

Quantum transport in alkane molecular wires: effects of binding modes and anchoring groups

Effects of binding modes and anchoring groups on nonequilibrium electronic transport properties of alkane molecular wires are investigated from atomic first-principles based on density functional theory and nonequilibrium Green's function formalism. Four typical binding modes, top, bridge, hcp-hollow, and fcc-hollow, are considered at one of the two contacts. For wires with three different anchoring groups, dithiol, diamine, or dicarboxylic acid, the low bias conductances resulting from the four binding modes are all found to have either a high or a low value, well consistent with recent experimental observations. The trend can be rationalized by the behavior of electrode-induced gap states at small bias. When bias increases to higher values, states from the anchoring groups enter into the bias window and contribute significantly to the tunneling process so that transport properties become more complicated for the four binding modes. Other low bias behaviors including the values of the inverse length scale for tunneling characteristic, contact resistance, and the ratios of the high/low conductance values are also calculated and compared to experimental results. The conducting capabilities of the three anchoring groups are found to decrease from dithiol, diamine to dicarboxylic-acid, largely owing to a decrease in binding strength to the electrodes. Our results give a clear microscopic picture to the transport physics and provide reasonable qualitative explanations for the corresponding experimental data.

Efficacy and safety of monotherapy of sitagliptin compared with metformin in patients with type 2 diabetes

AIM

To compare the efficacy and safety of monotherapy with sitagliptin and metformin in treatment-naïve patients with type 2 diabetes.

METHODS

In a double-blind study, 1050 treatment-naïve patients (i.e. not taking an antihyperglycaemic agent for > or =16 weeks prior to study entry) with type 2 diabetes and an HbA(1c) 6.5-9% were randomized (1:1) to treatment with once-daily sitagliptin 100 mg (N = 528) or twice-daily metformin 1000 mg (N = 522) for 24 weeks. Metformin was up-titrated from 500 to 2000 mg per day (or maximum tolerated daily dose > or =1000 mg) over a period of 5 weeks. The primary analysis used a per-protocol (PP) approach to assess whether sitagliptin was non-inferior to metformin based on HbA(1c) change from baseline at week 24. Non-inferiority was to be declared if the upper boundary of the 95% confidence interval (CI) for the between-group difference in this endpoint was <0.40%.

RESULTS

From a mean baseline HbA(1c) of 7.2% in the PP population, HbA(1c) change from baseline was -0.43% with sitagliptin (n = 455) and -0.57% with metformin (n = 439). The between-group difference (95% CI) was 0.14% (0.06, 0.21), thus confirming non-inferiority. Baseline HbA(1c) influenced treatment response, with larger reductions in HbA(1c) observed in patients with baseline HbA(1c)> or =8% in the sitagliptin (-1.13%; n = 74) and metformin (-1.24%; n = 73) groups. The proportions of patients at week 24 with HbA(1c) values at the goals of <7 or <6.5% were 69 and 34% with sitagliptin and 76 and 39% with metformin, respectively. Fasting plasma glucose changes from baseline were -11.5 mg/dL (-0.6 mmol/l) and -19.4 mg/dl (-1.1 mmol/l) with sitagliptin and metformin, respectively (difference in LS mean change from baseline [95% CI] = 8.0 mg /dl [4.5,11.4]). Both treatments led to similar improvements from baseline in measures of homeostasis model assessment-beta cell function (HOMA-beta) and insulin resistance (HOMA-IR). The incidence of hypoglycaemia was 1.7% with sitagliptin and 3.3% with metformin (p = 0.116). The incidence of gastrointestinal-related adverse experiences was substantially lower with sitagliptin (11.6%) compared with metformin (20.7%) (difference in incidence [95% CI] = -9.1% [-13.6,-4.7]), primarily because of significantly decreased incidences of diarrhoea (3.6 vs. 10.9%; p < 0.001) and nausea (1.1 vs. 3.1%; p = 0.032). Body weight was reduced from baseline with both sitagliptin (LS mean change [95% CI] = -0.6 kg [-0.9,-0.4]) and metformin (-1.9 kg [-2.2, -1.7]) (p < 0.001 for sitagliptin vs. metformin).

CONCLUSIONS

In this 24-week monotherapy study, sitagliptin was non-inferior to metformin in improving HbA(1c) in treatment-naïve patients with type 2 diabetes. Although both treatments were generally well tolerated, a lower incidence of gastrointestinal-related adverse experiences was observed with sitagliptin.

Effect of the ratios of diameter of silo to bead on the pressure screening in granular columns

We present the apparent mass measurements at the bottom of granular packings for different bead and silo sizes. The redirection parameter K in Janssen theory is found to increase with the ratios of the diameter of the silo to the bead. We attribute this feature to the friction between the beads and the confining wall of silo; it is the role of friction that leads to variations in the shielding of vertical stresses as well as pressure screening.

O+OH-->O(2)+H: A key reaction for interstellar chemistry. New theoretical results and comparison with experiment

We report extensive, fully quantum, time-independent (TID) calculations of cross sections at low collision energies and rate constants at low temperatures for the O+OH reaction, of key importance in the production of molecular oxygen in cold, dark, interstellar clouds and in the chemistry of the Earth's atmosphere. Our calculations are compared with TID calculations within the J-shifting approximation, with wave-packet calculations, and with quasiclassical trajectory calculations. The fully quantum TID calculations yield rate constants higher than those from the more approximate methods and are qualitatively consistent with a low-temperature extrapolation of earlier experimental values but not with the most recent experiments at the lowest temperatures.

Hemoglobin Hakkari: an autosomal dominant form of beta thalassemia with inclusion bodies arising from de novo mutation in exon 2 of beta globin gene

Certain beta globin gene mutations produce a thalassemia major phenotype in the heterozygous state. While most such patients have thalassemia intermedia, we describe a young Guatemalan child with a de novo mutation in the beta globin gene, codon 31 T --> G (Hemoglobin Hakkari), who developed severe anemia at the age of 10 months and remains transfusion-dependent. The substitution of B13 leucine with arginine in the beta globin results in alteration of a critical heme contact point resulting in an extremely unstable variant hemoglobin and a clinical picture that is characterized by ineffective erythropoiesis and numerous intracytoplasmic inclusions within the erythrocyte precursors of the bone marrow. .

Low-pressure membrane integrity tests for drinking water treatment: A review

Low-pressure membrane systems, including microfiltration (MF) and ultrafiltration (UF) membranes, are being increasingly used in drinking water treatments due to their high level of pathogen removal. However, the pathogen will pass through the membrane and contaminate the product if the membrane integrity is compromised. Therefore, an effective on-line integrity monitoring method for MF and UF membrane systems is essential to guarantee the regulatory requirements for pathogen removal. A lot of works on low-pressure membrane integrity tests have been conducted by many researchers. This paper provides a literature review about different low-pressure membrane integrity monitoring methods for the drinking water treatment, including direct methods (pressure-based tests, acoustic sensor test, liquid porosimetry, etc.) and indirect methods (particle counting, particle monitoring, turbidity monitoring, surrogate challenge tests). Additionally, some information about the operation of membrane integrity tests is presented here. It can be realized from this review that it remains urgent to develop an alternative on-line detection technique for a quick, accurate, simple, continuous and relatively inexpensive evaluation of low-pressure membrane integrity. To better satisfy regulatory requirements for drinking water treatments, the characteristic of this ideal membrane integrity test is proposed at the end of this paper.

Non-viral Smad7 gene delivery and attenuation of postoperative peritoneal adhesion in an experimental model

BACKGROUND

Postoperative intra-abdominal adhesion is associated with high morbidity and mortality. Smad7, a protein that occupies a strategic position in fibrogenesis, inhibits the transforming growth factor (TGF) beta/Smad signalling pathway. In this study the therapeutic potential of exogenous Smad7 in preventing fibrogenesis in postoperative intra-abdominal adhesion was investigated.

METHODS

Intra-abdominal adhesion was induced in a rodent model by peritoneal abrasion. Smad7 was delivered into the peritoneal cavity by a non-viral ultrasound-microbubble-mediated naked gene transfection system. The effect of Smad7 transgene on adhesion formation was studied by measuring changes in TGF-beta, fibrogenic factors, alpha-SMA and Smad2/3 activation in the anterior abdominal wall.

RESULTS

Four weeks after surgical abrasion, all rats developed significant peritoneal adhesion with enhanced TGF-beta expression, increased levels of extracellular matrix components and activated myofibroblasts, accompanied by decreased Smad7 expression and increased Smad2/3 activation. In rats treated with the Smad7 transgene, the incidence and severity of peritoneal adhesion were significantly reduced, with biochemical downregulation of fibrogenic factors and inhibition of Smad2/3 activation. Serial quantitation using magnetic resonance imaging revealed a significant reduction in adhesion areas from day 14 onwards.

CONCLUSION

Ultrasound-microbubble-mediated gene transfection provides timely targeted gene delivery for the treatment of postoperative peritoneal adhesions.

Lysophosphatidic acid-induced platelet shape change revealed through LPA(1-5) receptor-selective probes and albumin

Lysophosphatidic acid (LPA), a component of mildly-oxidized LDL and the lipid rich core of atherosclerotic plaques, elicits platelet activation. LPA is the ligand of G protein-coupled receptors (GPCR) of the EDG family (LPA(1-3)) and the newly identified LPA(4-7) subcluster. LPA(4), LPA(5) and LPA(7) increase cellular cAMP levels that would induce platelet inhibition rather than activation. In the present study we quantified the mRNA levels of the LPA(1-7) GPCR in human platelets and found a rank order LPA(4) = LPA(5) > LPA(7) > LPA(6) = LPA(2) >> LPA(1) > LPA(3). We examined platelet shape change using a panel of LPA receptor subtype-selective agonists and antagonists and compared them with their pharmacological profiles obtained in heterologous LPA(1-5) receptor expression systems. Responses to different natural acyl and alkyl species of LPA, and octyl phosphatidic acid analogs, alpha-substituted phosphonate analogs, N-palmitoyl-tyrosine phosphoric acid, N-palmitoyl-serine phosphoric acid were tested. All of these compounds elicited platelet activation and also inhibited LPA-induced platelet shape change after pre-incubation, suggesting that receptor desensitization is likely responsible for the inhibition of this response. Fatty acid free albumin (10 microM) lacking platelet activity completely inhibited platelet shape change induced by LPA with an IC(50) of 1.1 microM but had no effect on the activation of LPA(1,2,3,&5) expressed in endogenously non-LPA-responsive RH7777 cells. However, albumin reduced LPA(4) activation and shifted the dose-response curve to the right. LPA(5) transiently expressed in RH7777 cells showed preference to alkyl-LPA over acyl-LPA that is similar to that in platelets. LPA did not increase cAMP levels in platelets. In conclusion, our results with the pharmacological compounds and albumin demonstrate that LPA does not induce platelet shape change simply through activation of LPA(1-5), and the receptor(s) mediating LPA-induced platelet activation remains elusive.

Ecology-based screen identifies new metabolites from a Cordyceps-colonizing fungus as cancer cell proliferation inhibitors and apoptosis inducers

OBJECTIVES

This study aims to identify new anti-cancer agents from Cordyceps-colonizing fungi, using an ecology-based approach. It also aims to explore their anti-cell proliferative mechanisms, and to evaluate their anti-tumour effects in vivo.

MATERIALS AND METHODS

Extracts from Cordyceps-colonizing fungi were tested on HeLa cells, and active extracts were separated to obtain anti-tumour metabolites; their structures were elucidated by mass and nuclear magnetic resonance spectroscopy. Cell cycle analysis was evaluated using flow cytometry. Tumour formation assays were performed using C57BL/6J mice.

RESULTS

Based on ecological considerations, the selected extracts were subjected to initial anti-tumour screening. Bioassay-guided fractionation of the active extract afforded two new epipolythiodioxopiperazines, named gliocladicillins A (1) and B (2). (A) 1 and B (2) inhibited growth of HeLa, HepG2 and MCF-7 tumour cells. Further study demonstrated that both preparations arrested the cell cycle at G(2)/M phase in a dose-dependent manner, and induced apoptosis through up-regulation of expression of p53, p21, and cyclin B, and activation of caspases-8, -9 and -3. These data imply that gliocladicillins A (1) and B (2) induce tumour cell apoptosis through both extrinsic and intrinsic pathways. In addition, in vivo studies showed that they displayed significant inhibitory effects on cell population growth of melanoma B16 cells implanted into immunodeficient mice.

CONCLUSIONS

Gliocladicillins A (1) and B (2) are effective anti-tumour agents in vitro and in vivo and should be further evaluated for their potential in clinical use.