Epitaxial graphene on SiC(0001): more than just honeycombs

Using scanning tunneling microscopy with Fe-coated W tips and first-principles calculations, we show that the interface of epitaxial graphene/SiC(0001) is a warped graphene layer with hexagon-pentagon-heptagon (H(5,6,7)) defects that break the honeycomb symmetry, thereby inducing a gap and states below E(F near the K point. Although the next graphene layer assumes the perfect honeycomb lattice, its interaction with the warped layer modifies )the dispersion about the Dirac point. These results explain recent angle-resolved photoemission and carbon core-level shift data and solve the long-standing problem of the interfacial structure of epitaxial graphene on SiC(0001).

Evidence for an anomalous like-sign dimuon charge asymmetry

We measure the charge asymmetry A ≡ (N++ - N--)/(N++ + N--) of like-sign dimuon events in 6.1 fb-1 of pp collisions recorded with the D0 detector at a center-of-mass energy square root(s) = 1.96   TeV at the Fermilab Tevatron collider. From A we extract the like-sign dimuon charge asymmetry in semileptonic b-hadron decays: A(sl)(b) = -0.009 57 ± 0.002 51(stat) ± 0.001 46(sys). It differs by 3.2 standard deviations from the standard model prediction A(sl)(b)(SM) = (-2.3(-0.6)(+0.5)) × 10(-4), and provides first evidence of anomalous CP violation in the mixing of neutral B mesons.

The clinical significance of occult hepatitis B transfusion in Taiwan--a look-back study

OBJECTIVES

A look-back study was conducted to determine the clinical significance of occult hepatitis B virus (HBV) blood transfusion in an HBV hyperendemic area.

AIM

To improve the blood transfusion safety.

BACKGROUND

Occult HBV is transmissible through blood transfusion in HBV-naÏve recipients. However, its impact on recipients with prevalent HBV infection in HBV hyperendemic areas is unclear.

METHODS/MATERIALS

In 2006, 12 occult HBV blood donors were found from 10 824 repository samples by nucleic acid testing. The 74 corresponding recipients were identified and their pre- and post-transfusion clinical information was gathered, and the living recipients were recalled for follow-up. From the available archival sera, the HBV DNA was examined and sub-genomic sequences between paired donor and recipient were compared using polymerase chain reaction-based assays.

RESULTS

Among the 74 recipients, 18 were still alive and 12 returned to our clinic. From the available serological profiles, 76% of recipients had ongoing or recovered HBV infection before transfusion. Only 24 recipients had available post-transfusion serological profiles and none seroconverted to be hepatitis B surface antigen (HBsAg) positive. Moreover, except for the prior HBsAg carriers, the recipients' HBV DNA levels after transfusion were low (<20 IU/mL). One recipient had identical HBV surface gene sub-genomic sequence (384 nucleotides) to his donor. After transfusion, no recipient developed post-transfusion hepatitis (PTH) and the clinical outcome was good.

CONCLUSION

In HBV hyperendemic areas, occult hepatitis B transfusion might not lead to HBsAg carriage or PTH. The risk of transfusion-transmitted HBV infection was probably lower than that in non-endemic areas because most recipients had already experienced HBV infection.

Aeolian sediment evidence that global cooling has driven late Cenozoic stepwise aridification in central Asia

It has been a long held view that uplift of the Tibetan Plateau dominated stepwise climatic drying in central Asia during the late Cenozoic. On the other hand, global cooling may also have forced Asian drying and the subsequent formation of aeolian deposits in north China. Until now, whether the Tibetan uplift or the global cooling has been the first-order driver controlling stepwise Asian drying has remained a contentious issue. In this study, we examine the thick aeolian silt deposit, which is regarded as a good archive of palaeoclimatic changes in central Asia and north China, in order to qualitatively reconstruct the drying process in Asia during the late Cenozoic. On the basis of our long-term field surveys, laboratory analyses and previous investigations, we have obtained time sequences of Asian drying from the early Miocene to late Pleistocene; we compare this newly reconstructed time series of Asian aridification with the time series of global cooling and Tibetan uplift to identify the first-order driver of stepwise Asian aridification. A good match between the drying and global cooling might indicate that global cooling was the most likely driver of stepwise drying in interior Asia. On the other hand, controversy regarding timing and amplitude of Tibetan uplift during the late Cenozoic suggests that the prevailing conclusion that Tibetan uplift forces Asian drying should be regarded as immature. A mechanism that global cooling drove the Asian drying is tentatively suggested.

Molecular hydrogen desorption from amorphous surfaces at low temperature

We studied the desorption of hydrogen molecules from amorphous silicates of composition (Fe(x)Mg(1 - x))(2)SiO(4) (0 < x < 1) using thermal programmed desorption (TPD). Selected measurements of formation of molecular hydrogen on and desorption from a single crystal olivine sample were done for comparison. The experiments were conducted in conditions as close as technically possible to those found in selected interstellar medium environments, where the formation of molecular hydrogen takes place on dust grains. From molecular desorption data, we derive the energy distribution of binding sites using a direct inversion method. The application of this type of data to the study of elementary processes of migration of atoms and molecules on and ejection from disordered surfaces at low temperature is discussed.

Peripheral adenosine A2A receptors are involved in carrageenan-induced mechanical hyperalgesia in mice

Here we studied the role of peripheral adenosine A(2A) receptors in mechanical hyperalgesia during inflammation using mice lacking the A(2A) receptors. Unilateral s.c. administration of the local inflammatory agent λ-carrageenan induced profound mechanical hyperalgesia 24 h after administration in the ipsilateral hind paw in wild-type mice. In homozygous mice lacking the A(2A) receptors, carrageenan-induced hyperalgesia was significantly reduced compared to wild type controls. The reduction in inflammatory hyperalgesia seen in A(2A) receptor knock-out mice was not associated with changes in paw edema. CGS 21680, a selective A(2A) receptor agonist, produced significantly more mechanical hyperalgesia in wild type females than in wild type males upon direct s.c. injection into the hindpaw whereas it had no effect upon systemic administration. The hyperalgesic effect of CGS 21680 was markedly reduced in the A(2A) knock-out mice of both sexes. Subcutaneous ZM-241,385, a selective A(2A) receptor antagonist, injected into the hindpaw reduced the mechanical hyperalgesia following carrageenan in female mice, but not in males. The results indicate that activation of peripheral adenosine A(2A) receptors during inflammation is associated with mechanical hyperalgesia, and that this effect is more prominent in females than in males.

In vitro cytotoxicity and hemocompatibility studies of Ti-Nb, Ti-Nb-Zr and Ti-Nb-Hf biomedical shape memory alloys

The in vitro cytotoxicity and hemocompatibility of the Ti-Nb, Ti-Nb-Zr and Ti-Nb-Hf biomedical shape memory alloys (SMAs) were investigated by cell culture (L-929 fibroblast cell), hemolytic test and platelet adhesion test, with CP Ti as a reference material. The cytotoxicity test indicates that all the Ti-Nb, Ti-Nb-Zr and Ti-Nb-Hf SMAs show over 94% cell viability for different incubation times (2, 4 and 7 days) in comparison with a negative control and CP Ti. The cell morphology observation shows good polygon-like adherent growth and proliferation of L-929 in the extracts of all the test samples and CP Ti. These results suggest excellent cytocompatibility for the Ti-Nb, Ti-Nb-Zr and Ti-Nb-Hf SMAs. The hemolytic test reveals that the hemolysis ratios of the Ti-Nb, Ti-Nb-Zr and Ti-Nb-Hf alloys are far less than 5%, so they cannot give rise to acute hemolysis. The platelet morphology observation shows almost the same adhered platelet morphology and activation ratio for the test samples in comparison with CP Ti, except the Ti-22Nb-6Hf alloy, which shows a lower activation ratio of platelets, indicating excellent blood compatibility. Therefore, it is proposed that the Ti-Nb, Ti-Nb-Zr and Ti-Nb-Hf SMAs will be candidates to replace Ti-Ni for biomedical applications.

Intracerebroventricular delivery of glucocerebrosidase reduces substrates and increases lifespan in a mouse model of neuronopathic Gaucher disease

Gaucher disease is caused by a deficit in the enzyme glucocerebrosidase. As a consequence, degradation of the glycolipids glucosylceramide (GluCer) and glucosylsphingosine (GluSph) is impaired, and their subsequent buildup can lead to significant pathology and early death. Type 1 Gaucher patients can be treated successfully with intravenous replacement enzyme, but this enzyme does not reach the CNS and thus does not ameliorate the neurological involvement in types 2 and 3 Gaucher disease. As one potential approach to treating these latter patients, we have evaluated intracerebroventricular (ICV) administration of recombinant human glucocerebrosidase (rhGC) in a mouse model of neuronopathic Gaucher disease. ICV administration resulted in enzyme distribution throughout the brain and alleviated neuropathology in multiple brain regions of this mouse model. Treatment also resulted in dose-dependent decreases in GluCer and GluSph and significantly extended survival. To evaluate the potential of continuous enzyme delivery, a group of animals was treated ICV with an adeno-associated viral vector encoding hGC and resulted in a further extension of survival. These data suggest that ICV administration of rhGC may represent a potential therapeutic approach for type 2/3 Gaucher patients. Preclinical evaluation in larger animals will be needed to ascertain the translatability of this approach to the clinic.

A mathematical model of the murine ventricular myocyte: a data-driven biophysically based approach applied to mice overexpressing the canine NCX isoform

Mathematical modeling of Ca(2+) dynamics in the heart has the potential to provide an integrated understanding of Ca(2+)-handling mechanisms. However, many previous published models used heterogeneous experimental data sources from a variety of animals and temperatures to characterize model parameters and motivate model equations. This methodology limits the direct comparison of these models with any particular experimental data set. To directly address this issue, in this study, we present a biophysically based model of Ca(2+) dynamics directly fitted to experimental data collected in left ventricular myocytes isolated from the C57BL/6 mouse, the most commonly used genetic background for genetically modified mice in studies of heart diseases. This Ca(2+) dynamics model was then integrated into an existing mouse cardiac electrophysiology model, which was reparameterized using experimental data recorded at consistent and physiological temperatures. The model was validated against the experimentally observed frequency response of Ca(2+) dynamics, action potential shape, dependence of action potential duration on cycle length, and electrical restitution. Using this framework, the implications of cardiac Na(+)/Ca(2+) exchanger (NCX) overexpression in transgenic mice were investigated. These simulations showed that heterozygous overexpression of the canine cardiac NCX increases intracellular Ca(2+) concentration transient magnitude and sarcoplasmic reticulum Ca(2+) loading, in agreement with experimental observations, whereas acute overexpression of the murine cardiac NCX results in a significant loss of Ca(2+) from the cell and, hence, depressed sarcoplasmic reticulum Ca(2+) load and intracellular Ca(2+) concentration transient magnitude. From this analysis, we conclude that these differences are primarily due to the presence of allosteric regulation in the canine cardiac NCX, which has not been observed experimentally in the wild-type mouse heart.

A pilot study of the clinical relevance of the relationship between the serum level of pregnancy-associated plasma protein A and the degree of acute coronary syndrome

Serum levels of pregnancy-associated plasma protein-A (PAPP-A), high-sensitivity C-reactive protein (hs-CRP) and tumour necrosis factor-alpha (TNF-alpha) were measured in 70 patients with acute coronary syndrome (ACS), comprising 18 with unstable angina (UA), 37 with acute myocardial infarction (AMI) and 15 with stable angina (SA); 15 healthy controls were also included. Levels of PAPP-A were significantly higher in the UA and AMI groups than in the SA and control groups. Levels of PAPP-A were similar in the SA and control groups, and higher in the ACS patients who were cardiac troponin T-negative (comprising UA and AMI patients) than in the control and SA groups. Levels of hs-CRP and TNF-alpha were significantly higher in the SA group than in the control group, significantly higher in the UA group than in the SA and control groups, and significantly higher in the AMI group than in all other groups. Levels of PAPP-A in ACS patients were positively correlated with levels of hs-CRP and TNF-alpha. It would seem, therefore, that PAPP-A is associated with inflammation and might be used to detect plaque instability and rupture before an increase in cardiac troponin T is detectable.

The synergy of honokiol and fluconazole against clinical isolates of azole-resistant Candida albicans

AIMS

To evaluate the interaction of fluconazole (FLC) and honokiol (HNK) in vitro and vivo against azole-resistant (azole-R) clinical isolates of Candida albicans.

METHODS AND RESULTS

A checkerboard microdilution method was used to study the in vitro interaction of FLC and HNK in 24 azole-R clinical isolates of C. albicans. In vivo antifungal activity was performed to further analyse the interaction between FLC and HNK. In the in vitro study, synergism was observed in all 24 FLC-resistant strains tested as determined by fractional inhibitory concentration index (FICI), and in 22 strains by Delta E models. No antagonistic activity was observed in any of the strains tested. These positive interactions were also confirmed by using the time-killing test for the selected strain C. albicans YL371, which shows strong susceptible to the combination of HNK and FLC. In the in vivo study, the mice with candidiasis were treated successfully by a combination therapy of HNK with FLC, the results showed a decrease of the colony forming unit in infected and treated animals compared to the controls, at the conditions of the treatment used in this study.

CONCLUSIONS

Synergistic activity of HNK and FLC against clinical isolates of FLC-resistant C. albicans was observed in vitro and in vivo.

SIGNIFICANCE AND IMPACT OF THE STUDY

This report might provide a potential therapeutic method to overcome the problem of drug-resistance in C. albicans.

Higher moments of net proton multiplicity distributions at RHIC

We report the first measurements of the kurtosis (κ), skewness (S), and variance (σ2) of net-proton multiplicity (Np-Np) distributions at midrapidity for Au+Au collisions at square root of s(NN)=19.6, 62.4, and 200 GeV corresponding to baryon chemical potentials (μB) between 200 and 20 MeV. Our measurements of the products κσ2 and Sσ, which can be related to theoretical calculations sensitive to baryon number susceptibilities and long-range correlations, are constant as functions of collision centrality. We compare these products with results from lattice QCD and various models without a critical point and study the square root of s(NN) dependence of κσ2. From the measurements at the three beam energies, we find no evidence for a critical point in the QCD phase diagram for μB below 200 MeV.

Three-particle coincidence of the long range pseudorapidity correlation in high energy nucleus-nucleus collisions

We report the first three-particle coincidence measurement in pseudorapidity (Δη) between a high transverse momentum (p⊥) trigger particle and two lower p⊥ associated particles within azimuth |Δϕ|<0.7 in square root of s(NN)=200 GeV d+Au and Au+Au collisions. Charge ordering properties are exploited to separate the jetlike component and the ridge (long range Δη correlation). The results indicate that the correlation of ridge particles are uniform not only with respect to the trigger particle but also between themselves event by event in our measured Δη. In addition, the production of the ridge appears to be uncorrelated to the presence of the narrow jetlike component.

Establishment and evaluation of a model of a community health service in an underdeveloped area of China

OBJECTIVES

To develop and evaluate an applicable model for a community health service (CHS) in an underdeveloped area of China that ensures efficient, convenient and affordable primary healthcare access for all residents.

STUDY DESIGN

The current study was carried out in Puyang, a typical medium-sized city in central-eastern China. Based on the healthcare requirements of the residents in Puyang, a CHS network was set up and its operation was evaluated from 1999 to 2006. The system is characterized by its focus on community health education (CHE).

METHODS

Firstly, 8231 residents, selected at random, were surveyed to investigate the healthcare requirements of the local residents. Meanwhile, the operation of the pre-existing healthcare resources was investigated in Puyang. Based on the information gained, a network-based CHS system was proposed and established, with CHE as the major focus. This study compared CHS operation prior to and after establishment of the network. Finally, an analytic hierarchy process based evaluation model was applied to evaluate the operation of the CHS network.

RESULTS

There was a high prevalence (86.98 per thousand) of chronic diseases among the residents who participated in this investigation. The majority (84.39%) of the residents who had healthcare requirements resorted to professional health care; the other residents did not have access to health services. Among those residents who sought professional treatment, 71.3% visited primary healthcare institutions. This information reflects the enormous requirement for a CHS in primary health care but the lack of accessibility among the residents; this motivated the authors to establish a system to solve the problem. The improvement in CHS operation after the network was established suggests the importance of a network for optimizing the primary healthcare system. The improvement was indicated by better understanding of the residents regarding the CHS, and enhanced capability of self-monitoring for chronic diseases such as hypertension after the network was established. Moreover, the residents' knowledge of health care was significantly increased and, accordingly, the incidence of health risk behaviour was reduced after the network was established. Furthermore, the CHE index between 1999 and 2006 showed good correlation (r=0.988, p<0.005) with the CHS index, suggesting the important role of CHE in CHS development.

CONCLUSIONS

A network-characterized CHS system was established in Puyang, and improved the primary healthcare situation. This study provides a feasible model for the development of a CHS in medium and small cities in underdeveloped parts of China.

Establishment and biological characterization of fibroblast cell line from the Langshan chicken

OBJECTIVE

We needed to establish an embryonic fibroblast cell line from the Langshan chicken (LSCEF61) to preserve their important genetic resources at the cellular level.

MATERIAL AND METHODS

The cell line was established from 9-day-old embryos by direct explant culture and cryopreservation techniques. Cell morphology, dynamic proliferation and any contamination present were tested, and the karyotype and levels of isoenzymes of lactic dehydrogenase and malic dehydrogenase were analysed. Four types of fluorescent protein exogenous genes for pEGFP-C(1), pEGFP-N(3), pEYFP-N(1) and pDsRed1-N(1) were transfected into the cells.

RESULTS

Showed that the cells were healthy and were of spindle shaped structure, without change in morphology. Cell growth curves were of typical S-shape. Assays for microbial contamination were negative. The LSCEF61 line showed no cross-contamination when assessed by isoenzyme analysis. Chromosome number (2n) = 78 on more than 90% of occasions. The four types of fluorescent protein extro-genes appeared to be expressed effectively with high transfection efficiency between 15.6% and 38.6%.

CONCLUSION

The cell line met each of the quality control standards required for the American Type Culture Collection. It had not only preserved the genetic resources of the important Langshan chicken at the cellular level, but also provided valuable material for genomic, post-genomic and somatic cell cloning research and other applications.

Search for Randall-Sundrum gravitons in the dielectron and diphoton final states with 5.4 fb(-1) of data from pp collisions at square root(s) = 1.96 TeV

Using 5.4  fb(-1) of integrated luminosity from pp collisions at square root(s)=1.96  TeV collected by the D0 detector at the Fermilab Tevatron Collider, we search for decays of the lightest Kaluza-Klein mode of the graviton in the Randall-Sundrum model to ee and γγ. We set 95% C.L. lower limits on the mass of the lightest graviton between 560 and 1050 GeV for values of the coupling k/M(Pl) between 0.01 and 0.1.

Analyzing endodontic infections by deep coverage pyrosequencing

Bacterial diversity in endodontic infections has not been sufficiently studied. The use of modern pyrosequencing technology should allow for more comprehensive analysis than traditional Sanger sequencing. This study investigated bacterial diversity in endodontic infections through taxonomic classification based on 16S rRNA gene sequences generated by 454 GS-FLX pyrosequencing and conventional Sanger capillary sequencing technologies. Sequencings were performed on 7 specimens from endodontic infections. On average, 47 vs. 28,590 sequences were obtained per sample for Sanger sequencing vs. pyrosequencing, representing a 600-fold difference in "depth-of-coverage". Based on Ribosomal Database Project (RDP II) Classifier analysis, pyrosequencing identified 179 bacterial genera in 13 phyla, which was significantly more than Sanger sequencing. The phylum Bacteroidetes was the most prevalent bacterial phylum. These results indicate that bacterial communities in endodontic infections are more diverse than previously demonstrated. In addition, deep-coverage pyrosequencing of the 16S rRNA gene revealed low-abundance micro-organisms with potential clinical implications.