Role of ABCB1 C1236T, G2677T, and C3435T genetic polymorphisms in the development of acute leukemia in a Chinese population

We carried out a case-control study to examine the relationship between the ATP-binding cassette subfamily B member 1 (ABCB1) gene polymorphisms C1236T, G2677T, and C3435T and risk of acute leukemia in a Chinese population. Between May 2013 and April 2015, we recruited 164 acute leukemia patients and 285 healthy controls, and determined polymorphism genotypes by polymerase chain reaction-restriction fragment length polymorphism. Using unconditional logistic regression analysis, we observed that in comparison to the wild-type sequence, the TT genotype [odds ratio (OR) = 2.15, 95% confidence interval (CI) = 1.12-4.10; P = 0.01] and the T allele (OR = 1.39, 95%CI = 1.05-1.86; P = 0.02) of ABCB1 G2677T were associated with acute leukemia susceptibility. The TT genotype (OR = 2.03, 95%CI = 1.11- 3.69; P = 0.01) and the T allele (OR = 1.39, 95%CI = 1.05-1.85; P = 0.02) of the C3435T polymorphism also increased acute leukemia risk compared to the wild-type form. However, no significant relationship was established between the ABCB1 C1236T variant and this disease. Our results suggest that the ABCB1 G2677T and C3435T sequence variations may affect susceptibility to acute leukemia.

[Effect of mitochondrial apoptosis on pulmonary fibrosis in rats with severe scald injury]

OBJECTIVE

To explore the role of mitochondrial apoptosis on pulmonary fibrosis in rats with severe scald injury.

METHODS

According to the random digital table, a total number of 32 Wistar rats were divided into 4 groups: sham burn (group A), burn group (group B), 12-week post burn recovery group (group C), and 12-week post burn recovery plus a second burn injury group (group D). In group A and group B, lung tissues were harvested on post burn day 4. After received first burn injury 12 weeks, the group C and group D received separately a second sham burn injury and burn injury. Lung tissues were harvested on post burn day 4 after the second burn injury. All tissues were examined for cells apoptosis by Terminal-deoxynucleoitidyl Transferase Mediated Nick End Labeling (TUNEL). Pulmonary fibrosis was assessed by Masson trichrome staining and Sirius red staining. The protein expression levels of cleaved Caspase-3, Bax and Bcl-2 were assessed by Western blot.

RESULTS

Both Masson trichrome staining and Sirius red staining showed obvious pulmonary fibrosis in group C and group D. The apoptosis rates of group B, C and D were significantly higher than that in group A ((15.50±3.30)%, (7.88±3.10)%, (15.88±3.23)% vs (2.10±1.07)%, all P<0.05). Compared to group A, cleaved Caspase-3 levels were significantly higher in group B, C and D ((0.59±0.11), (0.33±0.08), (0.73±0.13) vs (0.16±0.05), all P<0.05). The ratio of Bax/Bcl-2 in group B, C and D also increased significantly ((2.08±0.30), (0.83±0.09), (1.54±0.12) vs (0.64±0.05), all P<0.05).

CONCLUSION

Severe burn injury can induce pulmonary fibrosis and mitochondrial apoptosis may play an important role in the development of pulmonary fibrosis.

[Comparative proteomics study on lung tissue in early stage of burn-blast combined injury in rats]

OBJECTIVE

To explore changes in the proteomics of lung tissue in early stage of burn-blast combined injury in rats.

METHODS

According to a random digital table, a total number of 18 Sprague Dawley (SD) rats were divided into burn-blast combined injury group (n=9) and blast injury group (n=9). Lung protein samples were collected at 6 h post injury. 2-DE was performed to separate proteins. After silver staining, the protein of differential expression were analyzed by PQ Quest and then identified by matrix-assisted laser desorption/ionization time of fight mass spectrometry (MALDI-TOF-MS). The features of the changes of proteomics of rat lung after burn-blast combined injury were studied by biological spectrometry, protein bank and reference article analysis technique. At same time, pathologic changes of the lung were monitored after injury.

RESULTS

After removing death drain during the experiment, each group contained 8 rats and the results were analyzed statistically. Well focused and distinct 2-DE maps with good reproducibility were obtained, means of 736±47 and 782±30 protein spots were detected from the blast injury group and burn-blast combined injury group and the matching rates were 91%. From the two groups, 14 differential protein spots expressions were analyzed by MALDI-TOF-MS, of which 10 proteins were up-regulated and 4 proteins were down-regulated in burn-blast combined injury group. 12 different expression proteins were identified in the lung through 2-DE, mass spectrometry and protein date base, including heat shock 27 protein 1, heat shock 70 protein 1, carbonic anhydrase 2, cytochrome c oxidase, ATP synthase subunit alpha, Ca(2+) -transporting ATPase et al, which took part in stress reaction, metabolism, immune response and cytoskeleton.

CONCLUSIONS

Burn-blast combined injury could induce dramatically changes of proteomics in lung tissue at early stage. The mechanism probably involves several proteins associated with oxidative stress, energy metabolism, immune response and cytoskeleton.

Dosimetric and clinical toxicity comparison of critical organ preservation with three-dimensional conformal radiotherapy, intensity-modulated radiotherapy, and RapidArc for the treatment of locally advanced cancer of the pancreatic head

PURPOSE

We compared dosimetry and clinical toxicity for 3-dimensional conformal radiotherapy (3D-crt), intensity-modulated radiotherapy (imrt), and RapidArc (Varian Medical Systems, Palo Alto, CA, U.S.A.) in locally advanced pancreatic cancer (lapcc). We hypothesized that the technique with better sparing of organs at risk (oars) and better target dose distributions could lead to decreased clinical toxicity.

METHODS

The study analyzed 280 patients with lapcc who had undergone radiotherapy. The dosimetry comparison was performed using 20 of those patients. Dose-volume histograms for the target volume and the oars were compared. The clinical toxicity comparison used the 280 patients who received radiation with 3D-crt, imrt, or RapidArc.

RESULTS

Compared with 3D-crt, RapidArc and imrt both achieved a better conformal index, homogeneity index, V95%, and V110%. Compared with 3D-crt or imrt, RapidArc reduced the V10, V20, and mean dose to duodenum, the V20 of the right kidney, and the liver mean dose. Compared with 3D-crt, RapidArc reduced the V35, and V45 of duodenum, the mean dose to small bowel, and the V15 of right kidney. The incidences of grades 3 and 4 diarrhea (p = 0.037) and anorexia (p = 0.042) were lower with RapidArc than with 3D-crt, and the incidences of grades 3 and 4 diarrhea (p = 0.027) were lower with RapidArc than with imrt.

CONCLUSIONS

Compared with 3D-crt or imrt, RapidArc showed better sparing of oars, especially duodenum, small bowel, and right kidney. Also, fewer acute grades 3 and 4 gastrointestinal toxicities were seen with RapidArc than with 3D-crt or imrt. A technique with better sparing of oars and better target dose distributions could result in decreased clinical toxicities during radiation treatment for lapcc.

Association between PAI-1 polymorphisms and plasma PAI-1 level with sepsis in severely burned patients

We investigated the association between plasminogen activator inhibitor-1 (PAI-1) polymorphisms and plasma PAI-1 level with sepsis in severely burned patients. A total of 182 patients with burn areas lager than 30% of the body surface area were enrolled in this study. Peripheral blood samples were obtained from 103 patients with sepsis (sepsis group) and 79 patients without sepsis (control group). An allele-specific polymerase chain reaction assay was used to determine PAI-1 polymorphism 4G/5G distribution. Plasma PAI-1 levels were detected using an enzyme-linked immunosorbent assay. The frequency of the 4G/4G genotype and the 4G allele frequency in the sepsis group were 42.7 and 62.1% respectively, which were significantly higher than those in the control group (P < 0.05). Sepsis patients had a significantly higher plasma PAI-1 level than the control group (P < 0.05). Compared with the 5G/5G genotype, PAI-1 concentrations were significantly higher in the 4G/4G genotype (P < 0.05). The study indicates that the 4G/5G promoter polymorphism of PAI-1 gene may be related to the susceptibility to burn sepsis and that the 4G/4G genotype may be an important genetic risk factor of burn sepsis. Additionally, PAI-1 concentrations in the serum are increased in patients with burn sepsis.

Conditional control of dendritic cell factor 1 expression by a tetracycline-inducible system

Dendritic cell factor 1 plays important roles in neural stem cells differentiation and in glioma cells proliferation, migration, and invasion. Here, we used a tetracycline&mdash;inducible system that regulates the expression of Dendritic cell factor 1 in glioma cells. We constructed two tet&mdash;inducible vectors, pTRE&mdash;EGFP&mdash;DCF1 and pTRE&mdash;LJM1&mdash;DCF1, by modifying the promoter PCMV. In the absence of tetracycline or doxycycline, the expression of Dendritic cell factor 1 in cells co&mdash;transfected with pTRE&mdash;EGFP&mdash;DCF1 or pTRE&mdash;LJM1&mdash;EGFP&mdash;DCF1 and ptTS&mdash;Neo was suppressed through binding of the tetracyline&mdash;controlled transcriptional suppressor to tetracycline response element, and the suppression was released by the addition of doxycycline. Our work has laid foundations for potential clinical application of cancer therapy in realizing artificial regulation of gene.

Safety of recombinant human granulocyte-macrophage colony-stimulating factor in healing pediatric severe burns

We explored the safety of recombinant human granulocyte-macrophage colony-stimulating factor (rhGM-CSF) for healing burns in children. Subjects were randomly assigned to two groups: the experimental group received external rhGM-CSF gel, and the control group received rhGM-CSF gel matrix components, applied to the burn surface. Neither group was given any other drugs that promote wound healing. Each day we recorded the pulse, body temperature, and respiration status in the two groups. We detected the blood routine, urine routine, and hepatic and renal function before the patients received drug treatment and after 72 h. The wound scab and healing states in the two groups were recorded every 4 days to evaluate wound healing rate and time taken for complete healing. Adverse reactions and their rate of occurrence were also recorded. The median time of healing was 15 days in the experimental group and 19 days in the control group (log-rank χ(2) = 5.139, P < 0.05). After 10 days, the experimental group healing rate was consistently higher than that of the control group (significantly different using intuitive analysis), suggesting the experimental group method was more effective. There were no obvious adverse reactions. There was no significant difference between the blood routine, urine routine, and liver and kidney function in the two groups before the treatment and after 3 days (P > 0.05). Compared with saline treatment of severe burns, rhGM-CSF can effectively shorten the healing time without significant adverse reactions, and is an effective and safe treatment for burns in children.

Helicobacter pylori-induced Sonic Hedgehog expression is regulated by NFκB pathway activation: the use of a novel in vitro model to study epithelial response to infection

BACKGROUND

Helicobacter pylori (H. pylori) infection leads to acute induction of Sonic Hedgehog (Shh) in the stomach that is associated with the initiation of gastritis. The mechanism by which H. pylori induces Shh is unknown. Shh is a target gene of transcription factor Nuclear Factor-κB (NFκB). We hypothesize that NFκB mediates H. pylori-induced Shh.

MATERIALS AND METHODS

To visualize Shh ligand expression in response to H. pylori infection in vivo, we used a mouse model that expresses Shh fused to green fluorescent protein (Shh::GFP mice) in place of wild-type Shh. In vitro, changes in Shh expression were measured in response to H. pylori infection using 3-dimensional epithelial cell cultures grown from whole dissociated gastric glands (organoids). Organoids were generated from stomachs collected from the fundic region of control and mice expressing a parietal cell-specific deletion of Shh (PC-Shh(KO) mice).

RESULTS

Within 2 days of infection, H. pylori induced Shh expression within parietal cells of Shh::GFP mice. Organoids expressed all major gastric cell markers, including parietal cell marker H(+) ,K(+) -ATPase and Shh. H. pylori infection of gastric organoids induced Shh expression; a response that was blocked by inhibiting NFκB signaling and correlated with IκB degradation. H. pylori infection of PC-Shh(KO) mouse-derived organoids did not result in the induction of Shh expression.

CONCLUSION

Gastric organoids allow for the study of the interaction between H. pylori and the differentiated gastric epithelium independent of the host immune response. H. pylori induces Shh expression from the parietal cells, a response mediated via activation of NFκB signaling.

The accumulation and subcellular distribution of arsenic and antimony in four fern plants

In the present study, Pteris cretica 'Albo-Lineata' (PC), Pteris fauriei (PF), Humata tyermanii Moore (HT), and Pteris ensiformis Burm (PE), were selected to explore additional plant materials for the phytoremediation of As and Sb co-contamination. To some extent, the addition of As and Sb enhanced the growth of HT, PE, and PF. Conversely, the addition of As and Sb negatively affected the growth of PC and was accompanied with the accumulation of high levels of As and Sb in the roots. The highest concentration of Sb was recorded as 6405 mg kg(-1) in the roots of PC, and that for As was 337 mg kg(-1) in the rhizome of PF. To some degree, As and Sb stimulated the uptake of each other in these ferns. Arsenic was mainly stored in the cytoplasmic supernatant (CS) fraction, followed by the cell wall (CW) fraction. In contrast, Sb was mainly found in the CW fraction and, to a lesser extent, in the CS fraction, suggesting that the cell wall and cytosol play different roles in As and Sb accumulation by fern plants. This study demonstrated that these fern plants show a good application potential in the phytoremediation of As and Sb co-contaminated environments.

Estrogen alone or in combination with parathyroid hormone can decrease vertebral MEF2 and sclerostin expression and increase vertebral bone mass in ovariectomized rats

The study is about the regulatory effects of estrogen and parathyroid hormone (PTH) on sclerostin, a protein that inhibits the Wnt/β-catenin pathway. The results indicate that estrogen may down-regulate sclerostin expression and that estrogen displays synergistic action with PTH. These results provide a new perspective on the relationship between estrogen and bone.

PURPOSE

To investigate whether estrogen can down-regulate SOST and MEF2 (myocyte enhancer factor 2) expression and whether co-treatment with estrogen and PTH has a stronger effect on suppressing SOST than PTH applied alone in ovariectomized rats.

METHODS

Forty-three-month-old virgin female Sprague-Dawley (SD) rats were ovariectomized and divided into four groups (n = 10). Another ten age-matched rats received sham operations as controls. After allowing 8 weeks for the development of vertebral osteopenia, the rats were administered the drug intervention. For this intervention, the estrogen group was subcutaneously injected with 17β-estradiol at 25 μg/kg body weight, the PTH group was injected with 80 μg/kg synthetic human PTH (1-34), and the co-treatment group was concurrently treated with PTH and estrogen at the above dosage. The OVX group and sham group were treated with vehicle. The drug treatment was conducted for 12 weeks. After the lumbar spine bone mineral density (BMD) was measured, the rats were sacrificed, and the lumbar spine and blood were collected for qPCR, Western blot, immunohistochemistry and other tests.

RESULTS

Estrogen can down-regulate MEF2 and sclerostin expression, and co-treatment with estrogen and PTH has a stronger effect on suppressing MEF2 and SOST mRNA than PTH alone. The co-treatment group displayed slightly higher bone mass and biomechanical properties than the PTH group, but the differences were not significant.

CONCLUSIONS

Estrogen appears to be a regulator of sclerostin, and the effect may involve suppressing MEF2s. Combined treatment with PTH and estrogen is not more beneficial for vertebral bone mass and strength than treatment with PTH alone in ovariectomized rats.

Improvement in the cutaneous disease activity of patients with dermatomyositis is associated with a better quality of life

BACKGROUND

Cutaneous dermatomyositis (DM) disease activity is associated with decreased quality of life.

OBJECTIVES

To assess if an improvement in quality of life, as measured by the Skindex-29 and patient-reported itch and pain on a 10-point visual analogue scale (VAS), correlated with an improvement in cutaneous DM disease activity.

METHODS

Patients with a completed cutaneous DM disease area and severity index [Cutaneous Dermatomyositis Disease Area and Severity Index (CDASI)] at two visits separated by at least 2 months were classified into responder (n = 15) and nonresponder (n = 30) groups according to the point change in the CDASI activity scores between visits. Responders had at least a four-point improvement in CDASI activity, indicating clinically relevant improvement.

RESULTS

The change from baseline to the follow-up visit of the Skindex-29 subscale scores for the responders vs. the nonresponders were significantly different for emotions (P < 0·01), functioning (P < 0·01) and symptoms (P < 0·01). The change in VAS score between responders and nonresponders was also significant for itch (P = 0·01) and pain (P = 0·04). There was no significant difference between the groups in terms of disease subtype, sex, race, age, treatment for DM, smoking history or a history of malignancy within 5 years of a diagnosis of DM.

CONCLUSIONS

This is the first study to demonstrate that the quality of life of patients with DM improved as their cutaneous disease activity decreased.

Physical exercise training and neurovascular unit in ischemic stroke

Physical exercise could exert a neuroprotective effect in both clinical studies and animal experiments. A series of related studies have indicated that physical exercise could reduce infarct volume, alleviate neurological deficits, decrease blood-brain barrier dysfunction, promote angiogenesis in cerebral vascular system and increase the survival rate after ischemic stroke. In this review, we summarized the protective effects of physical exercise on neurovascular unit (NVU), including neurons, astrocytes, pericytes and the extracellular matrix. Furthermore, it was demonstrated that exercise training could decrease the blood-brain barrier dysfunction and promote angiogenesis in cerebral vascular system. An awareness of the exercise intervention benefits pre- and post stroke may lead more stroke patients and people with high-risk factors to accept exercise therapy for the prevention and treatment of stroke.

Estimation of CYP2D6*10 genotypes on citalopram disposition in Chinese subjects by population pharmacokinetic assay

WHAT IS KNOWN AND OBJECTIVE

There is great interindividual variability in citalopram (CIT) pharmacokinetics. We attempted to establish a population pharmacokinetic (PPK) model of CIT in Chinese healthy subjects, to evaluate the effect of genetic polymorphism on CIT pharmacokinetics and to compare the PPK and non-compartmental (NCA) assays in the estimation of CIT bioequivalence.

METHODS

Blood samples of 23 healthy subjects were collected after administration of CIT; plasma concentration of CIT was analysed using LC/MS-MS. CYP2C19 and CYP2D6*10 genotypes were determined. PPK model was established by using nonlinear mixed-effect modelling (NONMEM). The model was evaluated using goodness-of-fit plots and relative error measurements. Bioequivalence of CIT was evaluated by both PPK and NCA method.

RESULTS AND DISCUSSION

The estimated population absorption rate constant (ka ), clearance (CL/F) and volume of distribution (Vd/F) in Chinese healthy subjects are 0.64 L/h, 12.7 L/h and 705 L, respectively. Different CYP2C19 and CYP2D6 genotypes have impacts on CIT pharmacokinetics. There is about 5.5% decrement of CL/F for each CYP2C19*2 or CYP2D6*10 allele. The 90% confidence interval of CIT bioavailability obtained from NCA and PPK model were 96.4-105.4% and 92.5-103.4%, respectively.

WHAT IS NEW AND CONCLUSION

The PPK of CIT is best characterized by a one-compartment disposition model with first-order absorption. CYP2C19 and CYP2D6 genotypes have impacts on the CL/F of CIT. Bioequivalence of CIT can be estimated by both NCA and PPK model.

Peripheral blood CD40-CD40L expression in human breast cancer

BACKGROUND

Breast cancer is the most common cancer in women. T cell-based immunotherapy for cancer has attracted much attention recently. CD40 and CD40L occupy an important position of specific immune response. In this paper, we want to study the role of co-stimulatory molecules CD40/CD40L and their clinical significance in peripheral blood of patients with breast cancer.

METHODS

Thirty breast cancer patients served as observation group, who were diagnosed as having infiltrating ductal breast cancer histopathologically, and 30 healthy as control group. Flow cytometric analysis was conducted to detect the expression of CD40 and CD40L on B and T lymphocytes in peripheral blood. The relationship between the CD40/CD40L expression levels and pathological grades was analyzed.

RESULTS

The expression levels of CD40/CD40L on B cells and T cells in breast cancer patients were significantly higher than those in the controls (all P < 0.001), and CD40/CD40L levels had a significant positive relationship with pathological grades (all P < 0.001).

CONCLUSIONS

The upregulated levels of co-stimulators CD40/CD40L on B cells and T cells may play an important role in the immune pathogenesis of breast cancer.

Abstract P2-14-11: Vitamin D Deficiency in Post-Menopausal Breast Cancer Survivors

Background: Breast cancer patients on aromatase inhibitors (AIs) are at an increased risk for decreased bone density and fractures. Given the important role vitamin D plays in bone metabolism, vitamin D deficiency may place these patients at an additional risk. Our objective was to examine the prevalence of and risk factors for vitamin D deficiency in post-menopausal breast cancer survivors (BCS) with current or past AI use. Materials and Methods: We conducted a cross-sectional study. Vitamin D levels were obtained utilizing the Diasorin radioimmunoassay using sera. Multiple logistic regression analyses were performed to identify independent risk factors associated with vitamin D deficiency. Results: In our cohort of 391 post-menopausal women with stage I to III breast cancer on AI therapy, the mean vitamin D level was 35 ng/mL, S.D. 12.49. Vitamin D levels were normally distributed in the cohort. Thirty five percent of women were vitamin D deficient, defined as a level less than 30 ng/mL. In our cohort, 73.4% of the participants had vitamin D supplementation documented in their chart; 26.8% of these women were still vitamin D deficient despite supplementation. Adjusting for demographic and clinical variables, non-white patients were more likely to be vitamin D deficient, adjusted odds ratio (AOR) of 2.00, 95% confidence interval (CI) 1.14-3.51, p=.004. Overweight (AOR 3.07, 95% CI 1.77-5.33, p&lt;.001) and obese (AOR 2.88, 95% CI 1.64-5.06, p&lt;.001) women were also at higher risk. In a second model, adjusting for the same covariates and chart-documented vitamin D supplementation, vitamin D supplementation was associated with lower risk for vitamin D deficiency (AOR .29, 95% CI .17-.48, p&lt;.001). The risk for non-white women (AOR 2.19, 95% CI 1.22-3.89, p=.009) and obese women (AOR 3.21, 95% CI 1.79-5.78, p&lt;.001) were increased after adjusting for vitamin D supplementation. Discussion: Hypovitaminosis D is common in BCS, and those who are non-white or have a BMI greater than 25 are at a higher risk of deficiency. When adjusting for vitamin D supplementation, the discrepancy between normal weight patients and obese patients became even more pronounced, suggesting that standard vitamin D supplementation may not be sufficient for these patients. In light of data linking hypovitaminosis D and bone health, oncologists should consider routine testing with particular attention to non-white or overweight patients, and repleting those patients who are deficient.

Citation Information: Cancer Res 2010;70(24 Suppl):Abstract nr P2-14-11.

Genetic and environmental contributions to body mass index: comparative analysis of monozygotic twins, dizygotic twins and same-age unrelated siblings

BACKGROUND

Earlier studies have established that a substantial percentage of variance in obesity-related phenotypes is explained by genetic components. However, only one study has used both virtual twins (VTs) and biological twins and was able to simultaneously estimate additive genetic, non-additive genetic, shared environmental and unshared environmental components in body mass index (BMI). Our current goal was to re-estimate four components of variance in BMI, applying a more rigorous model to biological and virtual multiples with additional data. Virtual multiples share the same family environment, offering unique opportunities to estimate common environmental influence on phenotypes that cannot be separated from the non-additive genetic component using only biological multiples.

METHODS

Data included 929 individuals from 164 monozygotic twin pairs, 156 dizygotic twin pairs, five triplet sets, one quadruplet set, 128 VT pairs, two virtual triplet sets and two virtual quadruplet sets. Virtual multiples consist of one biological child (or twins or triplets) plus one same-aged adoptee who are all raised together since infancy. We estimated the additive genetic, non-additive genetic, shared environmental and unshared random components in BMI using a linear mixed model. The analysis was adjusted for age, age(2), age(3), height, height(2), height(3), gender and race.

RESULTS

Both non-additive genetic and common environmental contributions were significant in our model (P-values<0.0001). No significant additive genetic contribution was found. In all, 63.6% (95% confidence interval (CI) 51.8-75.3%) of the total variance of BMI was explained by a non-additive genetic component, 25.7% (95% CI 13.8-37.5%) by a common environmental component and the remaining 10.7% by an unshared component.

CONCLUSION

Our results suggest that genetic components play an essential role in BMI and that common environmental factors such as diet or exercise also affect BMI. This conclusion is consistent with our earlier study using a smaller sample and shows the utility of virtual multiples for separating non-additive genetic variance from common environmental variance.

Electronic structure of epitaxial graphene layers on SiC: effect of the substrate

A strong substrate-graphite bond is found in the first all-carbon layer by density functional theory calculations and x-ray diffraction for few graphene layers grown epitaxially on SiC. This first layer is devoid of graphene electronic properties and acts as a buffer layer. The graphene nature of the film is recovered by the second carbon layer grown on both the (0001) and (0001[over]) 4H-SiC surfaces. We also present evidence of a charge transfer that depends on the interface geometry. Hence the graphene is doped and a gap opens at the Dirac point after three Bernal stacked carbon layers are formed.

Electronic structure of epitaxial graphene layers on SiC: effect of the substrate

A strong substrate-graphite bond is found in the first all-carbon layer by density functional theory calculations and x-ray diffraction for few graphene layers grown epitaxially on SiC. This first layer is devoid of graphene electronic properties and acts as a buffer layer. The graphene nature of the film is recovered by the second carbon layer grown on both the (0001) and (0001[over]) 4H-SiC surfaces. We also present evidence of a charge transfer that depends on the interface geometry. Hence the graphene is doped and a gap opens at the Dirac point after three Bernal stacked carbon layers are formed.

Hybrid atomistic-coarse-grained treatment of multiscale processes in heterogeneous materials: A self-consistent-field approach

A treatment of multiscale quasistatic processes that combines an atomistic description of microscopic heterogeneous ("near") regions of a material with a coarse-grained (quasicontinuum) description of macroscopic homogeneous ("far") regions is presented. The hybrid description yields a reduced system consisting of the original atoms of the near regions plus pseudoatoms (nodes of the coarse-graining mesh) of the far regions, which interact through an effective many-body potential energy V(eff) that depends on the thermodynamic state. The approximate nature of V(eff) gives rise to "ghost forces," which are reflected in spurious heterogeneities close to interfaces between near and far regions. The impact of ghost forces, which afflict all previous hybrid schemes, is greatly diminished by a self-consistent-field hybrid atomistic-coarse-grained (SCF-HACG) methodology. Tests of the SCF-HACG technique on a fully three-dimensional prototypal model [Lennard-Jones (12,6) crystal] yield thermomechanical properties (e.g., local stress) in good agreement with "exact" properties computed in the fully atomistic limit. The SCF-HACG method is also successfully used to characterize the grain boundary in a Lennard-Jones bicrystal.

Influence of quantum size effects on island coarsening

Surface x-ray scattering and scanning-tunneling microscopy experiments reveal novel coarsening behavior of Pb nanocrystals grown on Si(111)-(7 x 7). It is found that quantum size effects lead to the breakdown of the classical Gibbs-Thomson analysis. This is manifested by the lack of scaling of the island densities. In addition, island decay times tau are orders of magnitude faster than expected from the classical analysis and have an unusual dependence on the growth flux F (i.e., tau is approximately 1/F). As a result, a highly monodispersed 7-layer island height distribution is found after coarsening if the islands are grown at high rather than low flux rates. These results have important implications, especially at low temperatures, for the controlled growth and self-organization of nanostructures.

Coarse-grained free-energy-functional treatment of quasistatic multiscale processes in heterogeneous materials

A new treatment of quasistatic (reversible) multiscale processes in heterogeneous materials at nonzero temperature is presented. The system is coarse grained by means of a finite-element mesh. The coarse-grained free-energy functional (of the positions of the nodes of the mesh) appropriate to the thermodynamic-state variables controlled in the relevant process is minimized. Tests of the new procedure on a Lennard-Jonesium crystal yield thermomechanical properties in good agreement with the "exact" atomistic results.

Hybrid atomistic-coarse-grained treatment of thin-film lubrication. I

A technique that melds an atomistic description of the interfacial region with a coarse-grained description of the far regions of the solid substrates is presented and applied to a two-dimensional model contact consisting of planar solid substrates separated by a monolayer fluid film. The hybrid method yields results in excellent agreement with the "exact" (i.e., fully atomistic) results. The importance of a proper accounting for the elastic response of the substrates, which is reliably and efficiently accomplished through coarse-graining of the far regions, is demonstrated.

Deficient neurogenesis in forebrain-specific presenilin-1 knockout mice is associated with reduced clearance of hippocampal memory traces

To examine the in vivo function of presenilin-1 (PS1), we selectively deleted the PS1 gene in excitatory neurons of the adult mouse forebrain. These conditional knockout mice were viable and grew normally, but they exhibited a pronounced deficiency in enrichment-induced neurogenesis in the dentate gyrus. This reduction in neurogenesis did not result in appreciable learning deficits, indicating that addition of new neurons is not required for memory formation. However, our postlearning enrichment experiments lead us to postulate that adult dentate neurogenesis may play a role in the periodic clearance of outdated hippocampal memory traces after cortical memory consolidation, thereby ensuring that the hippocampus is continuously available to process new memories. A chronic, abnormal clearance process in the hippocampus may conceivably lead to memory disorders in the mammalian brain.

Differential effects of enrichment on learning and memory function in NR2B transgenic mice

It has been known that environmental enrichment leads to better learning and memory in mice. However, the molecular mechanisms are not known. In this study, we used the 10th-12th of the NR2B transgenic (Tg) lines, in which the NMDA receptor function is enhanced via the NR2B subunit transgene in neurons of the forebrain, to test the hypothesis of the involvement of NMDA receptor function in enrichment-induced better learning and memory. Consistent with our previous results, both larger long-term potentiation (LTP) in the hippocampus and superior learning and memory were observed in naive NR2B Tg mice even after the 10th-12th generation of breeding. After enrichment, wild-type mice exhibited overall improvement in their performances in contextual and cued conditioning, fear extinctions, and novel object recognition tasks. Interestingly, the same enrichment procedures could not further increase the performance of NR2B Tg mice in contextual conditioning, cued conditioning, or fear extinction, thereby indicating that enhanced NMDA receptor function can occlude these enrichment effects. However, we found that in the novel object recognition task enriched NR2B Tg mice exhibited much longer recognition memory (up to 1 week), compared to that (up to 3 days) in naive NR2B Tg mice. Furthermore, our biochemical experiments showed that enrichment significantly increased protein levels of GluR1, NR2B, and NR2A subunits of glutamate receptors in both wild-type and NR2B Tg mice. Therefore, our results suggest an interactive nature of molecular pathways involved in both environmental and genetic NMDA receptor manipulations for enhancing learning and memory.

Watermarking medical signals for telemedicine

Modern telecommunication infrastructure supports the possibility of delivering quality health care without the physical presence of medical experts. The integrity of biomedical signals being transmitted through communication channels must be established before their utilization. This paper investigates three digital watermarking techniques for signal integrity verification in an electroencephalogram (EEG) monitoring application for brain injury detection. The techniques studied are patchwork, least significant bit, and quantization watermarking methods. The three techniques are evaluated and compared in the following areas: sensitivity to noise contamination, robustness to EEG signal characteristic changes due to brain injury, and consistency under various communication channel models. The patchwork method performs best for noise contamination rejection among the three methods. The noise contamination detection rates of all three methods remain relatively stable across a wide range of EEG characteristics.

[The millipore rapid screening of hydantoinase production strains]

OBJECTIVE

To find a strain with a higher hydantoinase activity.

METHODS

The millipore rapid screening method was established to select the strains. The effects of several solvents on the rate of biotransformation were compared.

RESULTS

A hydantoinase production strain has been selected by the millipore rapid screening method. Tween-80 (1%) is found to be a suitable solvent to dissolve the substrate.

CONCLUSION

A new method is provided for rapid selection of hydantoinase production strains from large-scale samples. The difficulty in dissolving the substrate has been resolved to some extent.