The sodium channel band shapes the response to electric stimulation in retinal ganglion cells

To improve the quality of prosthetic vision, it is desirable to understand how targeted retinal neurons respond to stimulation. Unfortunately, the factors that shape the response of a single neuron to stimulation are not well understood. A dense band of voltage-gated sodium channels within the proximal axon of retinal ganglion cells is the site most sensitive to electric stimulation, suggesting that band properties are likely to influence the response to stimulation. Here, we examined how three band properties influence sensitivity using a morphologically realistic ganglion cell model in NEURON. Longer bands were more sensitive to short-duration pulses than shorter bands and increasing the distance between band and soma also increased sensitivity. Simulations using the known limits of band length and location resulted in a sensitivity difference of approximately 2. Additional simulations tested how changes to sodium channel conductance within the band influenced threshold and found that the sensitivity difference increased to a factor of nearly 3. This is close to the factor of 5 difference measured in physiological studies suggesting that band properties contribute significantly to the sensitivity differences found between different types of retinal neurons.

Lattice-Matched InAsN(X=0.38) on GaAs Grown by Molecular Beam Epitaxy

In this paper, we report the MBE growth of high nitrogen content lattice-matched InAs1−xNx (x=0.38) single crystal epitaxial films on GaAs. The nitrogen incorporation is about an order higher than previously reported on other mixed group V nitride alloys. These data are consistent with a nitrogen solubility limit calculation in various III-V binary alloys, which predicts orders of magnitude higher nitrogen incorporation in InAs than any other alloys. InAsN growths were obtained using a modified ECR-MBE system with atomic-nitrogen generated by an ECR plasma source. Improved crystal quality was obtained using a “template” growth technique. An x-ray linewidth of 270 arc-s was achieved on a 0.4 μm thick InAs0.62N0.38/GaAs multi-layer structure. Hall effect data show these InAsN films are semi-metallic.

Effects of KCNQ1 polymorphisms on the therapeutic efficacy of oral antidiabetic drugs in Chinese patients with type 2 diabetes

The aim of this study was to explore the impact of KCNQ1 variants on the responses to oral antidiabetic drugs in a Chinese study population. A 48-week randomized pharmacogenetics study compared the effects of repaglinide and rosiglitazone in 209 newly diagnosed patients with type 2 diabetes. In the repaglinide cohort, individuals who were rs2237892 TT homozygotes exhibited lower 2-h glucose levels and significantly higher cumulative attainment rates of target 2-h glucose levels (P(log-rank) = 0.0383) than the C allele carriers; patients with a greater number of rs2237892 C alleles showed larger augmentations in both fasting insulin and homeostasis model assessment of insulin resistance (HOMA-IR) (P = 0.0166 and 0.0026, respectively); moreover, the rs2237895 C allele was also associated with greater increments in both fasting insulin and HOMA-IR (P = 0.0274 and 0.0259, respectively). In contrast, only an association between rs2237897 and decrease in 2-h glucose levels was detected in the rosiglitazone cohort (P = 0.0321). Our results indicated that KCNQ1 polymorphisms are associated with repaglinide efficacy, and might also be associated with rosiglitazone response, in Chinese patients with type 2 diabetes.

Abstract P2-02-04: MRI Findings and Outcomes in an Underserved Breast Cancer Population Screened with BRCA Testing

Background: Patients with breast cancer and a familial risk and/or BRCA 1 or 2 mutations are at high risk of contralateral breast cancer and ipsilateral recurrence. While MRI screening is recommended for patients with BRCA mutations, and MRI staging for breast cancer is being increasingly used, the outcomes of such testing are not well described, especially in underserved populations. At Los Angeles County Hospital (LAC) for the last 3 years, we have enacted a program of genetic counseling and testing based standard guidelines as well as MRI evaluation of all patients newly diagnosed with breast cancer. LAC serves a population that includes a high number of indigent patients, primarily Hispanic (60%) and Asian (15%). Methods: We undertook a retrospective evaluation of all patients seen at LAC from March 2008 to March 2010 who underwent genetic counseling/testing and MRI as preoperative assessment for histologically documented breast cancer or followup after cancer treatment. IRB approval was obtained to extract data for this analysis. Demographic information along with clinical presentation, MRI and mammography results, additional imaging results, biopsy and surgical procedure and corresponding pathology data were obtained through the review of electronic medical records and clinic charts.

Results: A total of 90 patients had both genetic testing and MRI reports available. The median age of all tested patients was 41 years. Ethnicity was 78% Hispanic, 9% Asian, 7% African American, 2% Caucasian and 4% other. BRCA mutation was seen in 20 cases (22%), 12 BRCA-1, 8 BRCA-2, 4 variants of unknown significance, and 66 had no mutation. Breast mass or other symptoms were the mode of detection in 89% of the overall cohort, and 81% in mutation carriers. The index lesion was visible on MRI in 78% and by mammogram in 82% of all patients. Ipsilateral MRI showed 7 abnormal non-index findings in 6 patients (7%); 6 of 7 lesions biopsied showed cancer. In the contralateral breast, 7 abnormalities were noted on MRI, but only 5 were amenable to biopsy as 2 could not be visualized by any means on follow up, and 1 showed cancer. Interestingly, only one of the 13 patients with abnormal findings carried a mutation (BRCA-1) and this patient did not have cancer on contralateral lesion biopsy. Mastectomy was performed in 91% and 78% of patients with and without mutation. Conclusions: Screening, counseling and testing for BRCA mutations is feasible in an underserved population, with a 22% mutation identification rate. MRI detected 5 non-index ipsilateral cancers and one contralateral cancer among 90 patients, with none of the detected cancers among the 20 mutation carriers. While MRI staging may be effective at detecting additional cancers in this underserved and high familial risk population, this appears to be independent of BRCA status.

Citation Information: Cancer Res 2010;70(24 Suppl):Abstract nr P2-02-04.

Fine mapping of the sunflower resistance locus Pl(ARG) introduced from the wild species Helianthus argophyllus

Downy mildew, caused by Plasmopara halstedii, is one of the most destructive diseases in cultivated sunflower (Helianthus annuus L.). The dominant resistance locus Pl(ARG) originates from silverleaf sunflower (H. argophyllus Torrey and Gray) and confers resistance to all known races of P. halstedii. We mapped Pl(ARG) on linkage group (LG) 1 of (cms)HA342 × ARG1575-2, a population consisting of 2,145 F(2) individuals. Further, we identified resistance gene candidates (RGCs) that cosegregated with Pl(ARG) as well as closely linked flanking markers. Markers from the target region were mapped with higher resolution in NDBLOS(sel) × KWS04, a population consisting of 2,780 F(2) individuals that does not segregate for Pl(ARG). A large-insert sunflower bacterial artificial chromosome (BAC) library was screened with overgo probes designed for markers RGC52 and RGC151, which cosegregated with Pl(ARG). Two RGC-containing BAC contigs were anchored to the Pl(ARG) region on LG 1.

Preparation of a newly formulated long-acting ceftiofur hydrochloride suspension and evaluation of its pharmacokinetics in pigs

A new long-acting ceftiofur hydrochloride preparation was formulated and its physical properties, stability, and pharmacokinetics were investigated in this study. The prepared ceftiofur hydrochloride suspension demonstrated a milk white consistency, was easy to re-disperse and was stable in light, heat and humidity stability tests. Its other physical properties such as flowability, syringeability, settling volume ratio, particle size and distribution were perfectly consistent with the standard of Ministry of Agriculture of the People's Republic of China. After intramuscular administration of a single dose in swine (5 mg/kg B.W.), the drug concentration-time data in plasma were well fitted using the two-compartment open model. Compared with the ceftiofur hydrochloride preparation (EXCENEL) from Pfizer, the peak concentration (C(max)) in plasma was decreased by 2.34 times (P < 0.001), the half-life of elimination phase (T(1/2beta)) was 1.65 times longer (P < 0.001), and the therapeutic level of ceftiofur above the lowest effective plasma concentration of 0.2 microg/mL (T > 0.2) was prolonged from 87.20 h to 135.36 h (P < 0.001). The ceftiofur hydrochloride suspension prepared in this study provides therapeutically effective plasma concentrations for a longer duration, which make it more effective and more convenient to use in the treatment of respiratory diseases that require the maintenance of therapeutic plasma concentrations over a long duration.

The effects of plant traits and phylogeny on soil-to-plant transfer of 99Tc

Assessments of the behaviour of (99)Tc in terrestrial environments necessitate predicting soil-to-plant transfer. An experiment with 116 plant taxa showed that (99)Tc transfer to plants was positively related to plant dry weight but negatively related to % dry matter and age at exposure. Activities of (99)Tc analysed by hierarchical ANOVA coded with an angiosperm phylogeny revealed significant effects, with 55% of the variance between species explained at the Ordinal level and above. Monocots had significantly lower transfer of (99)Tc than Eudicots, within which Caryophyllales > Solanales > Malvales > Brassicales > Asterales > Fabales. There was a significant phylogenetic signal in soil-to-plant transfer of (99)Tc. This phylogenetic signal is used to suggest that, for example, a nominal Tc Transfer Factor of 5 could be adjusted to 2.3 for Monocots and 5.3 for Eudicots.

Association of genetic polymorphisms in the IL12-IFNG pathway with susceptibility to and prognosis of pulmonary tuberculosis in a Chinese population

Cytokines are crucial in activation of the cell-mediated immunity required for eliminating pathogens and controlling intracellular growth of Mycobacterium tuberculosis (TB). Genetic variants in the IL12-IFNG axis are hypothesized to be involved in the development and progression of TB. Genetic polymorphisms of rs2243115 and rs568408 in IL12A, rs3212227 in IL12B and rs2430561 in IFNG(+874) were detected in 522 pulmonary TB cases and 527 controls recruited from Yangzhong and Wujin County of China. It was found that genetic variants TG/GG of rs2243115(IL12A) were associated with a decreased risk of TB, with odds ratio (95% confidence interval) of 0.70 (0.49-0.99), whereas variant genotypes AT/TT of rs2430561(IFNG) conferred 82% less risk for treatment failure, with a hazard ratio of 0.18 (95% confidence interval 0.04-0.73). Cumulative effects analysis revealed that the risk of TB increased significantly with the number of unfavorable genotypes in IL12 genes. Furthermore, MDR analysis showed potential higher-order gene-gene and gene-environment interactions and indicated different outcomes based on distinct genotype profiles. Results from this study demonstrate that genetic polymorphisms of the IL12-IFNG pathway may individually or jointly contribute to the susceptibility to and prognosis of pulmonary TB.