A family-based association study identified CYP17 as a candidate gene for obesity susceptibility in Caucasians

The cytochrome P450c17α gene (CYP17) encodes a key biosynthesis enzyme of estrogen, which is critical in regulating adipogenesis and adipocyte development in humans. We therefore hypothesized that CYP17 is a candidate gene for predicting obesity. In order to test this hypothesis, we performed a family-based association test to investigate the relationship between the CYP17 gene and obesity phenotypes in a large sample comprising 1873 subjects from 405 Caucasian nuclear families of European origin recruited by the Osteoporosis Research Center of Creighton University, USA. Both single SNPs and haplotypes were tested for associations with obesity-related phenotypes, including body mass index (BMI) and fat mass. We identified three SNPs to be significantly associated with BMI, including rs3740397, rs6163, and rs619824. We further characterized the linkage disequilibrium structure for CYP17 and found that the whole CYP17 gene was located in a single-linkage disequilibrium block. This block was observed to be significantly associated with BMI. A major haplotype in this block was significantly associated with both BMI and fat mass. In conclusion, we suggest that the CYP17 gene has an effect on obesity in the Caucasian population. Further independent studies will be needed to confirm our findings.

HLA-DQ association and allele competition in Chinese narcolepsy

In Japanese, Koreans and Caucasians, narcolepsy/hypocretin deficiency is tightly associated with the DRB1*15:01-DQA1*01:02-DQB1*06:02 haplotype. Studies in African-Americans suggest a primary effect of DQB1*06:02, but this observation has been difficult to confirm in other populations because of high linkage disequilibrium between DRB1*15:01/3 and DQB1*06:02 in most populations. In this study, we studied human leucocyte antigen (HLA) class II in 202 Chinese narcolepsy patients (11% from South China) and found all patients to be DQB1*06:02 positive. Comparing cases with 103 unselected controls, and 110 and 79 controls selected for the presence of DQB1*06:02 and DRB1*15:01, we found that the presence of DQB1*06:02 and not DRB1*15:01 was associated with narcolepsy. In particular, Southern Chinese haplotypes such as the DRB1*15:01-DQA1*01:02-DQB1*06:01 and DRB1*15:01-DQA1*01:02-DQB1*05 were not associated with narcolepsy. As reported in Japanese, Koreans, African-Americans and Caucasians, additional protective effects of DQA1*01 (non-DQA1*01:02) and susceptibility effects of DQB1*03:01 were observed. These results illustrate the extraordinary conservation of HLA class II effects in narcolepsy across populations and show that DRB1*15:01 has no effect on narcolepsy susceptibility in the absence of DQB1*06:02. The results are also in line with a previously proposed 'HLA-DQ allelic competition model' that involves competition between non-DQA1*01:02, non-DQB1*06:02 'competent' (able to dimerize together) DQ1 alleles and the major DQα*01:02/ DQβ*06:02 narcolepsy heterodimer to reduce susceptibility.

Diaphragm valves reduce gastroesophageal reflux following cardiomyotomy for patients with achalasia

BACKGROUND

This study was designed to investigate the effect of a novel surgical method on cardia sphincter function and complication rates after Heller's cardiomyotomy for patients with achalasia.

METHODS

Forty-eight patients (19 males, mean age 34.0 +/- 10.5 years, range, 12-58) were included in this study. A spindle diaphragm valve was used in the surgery to rebuild the cardiac sphincter function. The efficacy of the surgery was determined by clinical assessment of symptoms and lower esophageal sphincter pressure (LESP) measurements. Barium meal examination was also used to evaluate the efficacy.

RESULTS

The mean LESP before surgery was 41.3 +/- 11.6 mmHg. It was reduced to 16.8 +/- 3.7 mmHg and 17.5 +/- 2.5 mmHg 3 and 12 months after surgery (P < 0.01). All patients were free of symptoms such as swallow difficulties or acid reflux during the follow up. However, barium swallow examination showed that 1 patient had mild reflux after the surgery. Clinical symptom scores on swallow difficulties/obstruction was reduced from 2.5 +/- 0.65 before surgery to 0.06 +/- 0.24 12 months after the surgery (P < 0.01).

CONCLUSION

A spindle diaphragm valve used with Heller's cardiomyotomy was associated with a very low incidence of post-surgical complications, such as gastroesophageal reflux. This technique may be used in treating all patients with achalasia.

SU-E-T-104: Commissioning and Dosimetric Characteristics of TrueBeam System: Composite Data of Three TrueBeam Machines

INTRODUCTION

A TrueBeam linear accelerator (TB-LINAC) is designed to deliver standard flattened and flattening-filter-free (FFF) beams. In our institute, three TB-LINAC units are installed. In this work, composite data of the three units and multi-unit comparison are presented.

METHODS

Each TB-LINAC can deliver photon beams from 4MV to 15MV, electron beams from 6MeV to 22MeV, and 6MV-FFF and 10MV-FFF. Dosimetric characteristics are systematically measured for commissioning including percent depth dose (PDD), beam profile, relative scatter factor, dynamic leaf shift, output factor and MLC leakage. Critic considerations of Pion of FFF photon beams and dosimetric penumbra are investigated.

RESULTS

All measured PDDs and profiles of photon and electron matched well across the three machines. Beam data were quantitatively compared and combined through average to yield composite beam data. The discrepancies among the machines were quantified using standard deviation (SD). For example, the mean SD of the PDDs among the three units is 0.12%, and the mean SD of the profiles is 0.40% for 10MV-FFF open fields. The variations of Pion of the chamber CC13 is 1.2±0.1% under 6MV-FFF and 2.0±0.5% from dmax to the 18cm-off-axis point at 35cm depth under 40×40cm² . The measured relative output factors range from 0.866 to 1.141 with the mean discrepancy of 0.06±0.04% among the three units. The measured wedge factors range from 0.863 to 1.254 with the mean overall discrepancy of 0.04±0.04%. The mean MLC transmission and dynamic leaf shift were measured from 1.0% to 1.5% and from 0.77mm to 0.96 mm from 4MV to 15MV. The mean penumbra of various photon beams are measured from 5.88±0.09mm to 5.99±0.13mm from 4MV to 15MV at 10cm depth of 10×10 cm² .

CONCLUSIONS

Dosimetric data demonstrated that the three units could and had been matched well. The systematically measured data might be useful for future reference.

WE-E-213CD-04: CT to Cone-Beam CT Deformable Registration With Simultaneous Intensity Correction

PURPOSE

To develop and validate a robust CT to cone-beam (CBCT) deformable image registration algorithm that can handle CBCT artifacts and intensity inconsistency, and thus can yield accurate registration results.

METHODS

We propose a new algorithm called Deformation with Intensity Simultaneously Corrected (DISC). DISC distinguishes itself from the original demons by performing an intensity correction procedure on the CBCT image at every iteration step of demons registration. Specifically, the intensity correction of a voxel in CBCT is achieved by matching the first and the second moments of the image intensities inside a patch around this voxel with those on the CT image. It is expected that such a strategy can remove artifacts in the CBCT image, as well as ensuring the intensity consistency between the two modalities and hence facilitating the registration process. DISC is implemented on computer graphics processing units (GPUs) using the compute unified device architecture (CUDA) programming environment. The performance of DISC has been qualitatively and quantitatively evaluated on a simulated patient case and six head-and- neck cancer patient data.

RESULTS

Visual inspection shows that original demons distorts the tissues after registration, especially in regions which are heavily degraded by artifacts. DISC, on the other hand, can effectively register CT and CBCT image even in regions contaminated by severe artifacts. The intensity corrected CBCT that extracted from the last iteration of DISC is artifact-free and has similar histogram distribution with the deformed CT.

CONCLUSIONS

We have developed a robust CT to CBCT deformable image registration method that properly deals with the CBCT artifacts and intensity inconsistency, and thus yields accurate registration results. This work is supported in part by the University of California Lab Fees Research Program, the Master Research Agreement from Varian Medical Systems, Inc., and the grants from the National Natural Science Foundation of China (No.30970866).

Disease-associated prion protein in neural and lymphoid tissues of mink (Mustela vison) inoculated with transmissible mink encephalopathy

Transmissible spongiform encephalopathies (TSEs) are diagnosed by immunodetection of disease-associated prion protein (PrP(d)). The distribution of PrP(d) within the body varies with the time-course of infection and between species, during interspecies transmission, as well as with prion strain. Mink are susceptible to a form of TSE known as transmissible mink encephalopathy (TME), presumed to arise due to consumption of feed contaminated with a single prion strain of ruminant origin. After extended passage of TME isolates in hamsters, two strains emerge, HY and DY, each of which is associated with unique structural isoforms of PrP(TME) and of which only the HY strain is associated with accumulation of PrP(TME) in lymphoid tissues. Information on the structural nature and lymphoid accumulation of PrP(TME) in mink is limited. In this study, 13 mink were challenged by intracerebral inoculation using late passage TME inoculum, after which brain and lymphoid tissues were collected at preclinical and clinical time points. The distribution and molecular nature of PrP(TME) was investigated by techniques including blotting of paraffin wax-embedded tissue and epitope mapping by western blotting. PrP(TME) was detected readily in the brain and retropharyngeal lymph node during preclinical infection, with delayed progression of accumulation within other lymphoid tissues. For comparison, three mink were inoculated by the oral route and examined during clinical disease. Accumulation of PrP(TME) in these mink was greater and more widespread, including follicles of rectoanal mucosa-associated lymphoid tissue. Western blot analyses revealed that PrP(TME) accumulating in the brain of mink is structurally most similar to that accumulating in the brain of hamsters infected with the DY strain. Collectively, the results of extended passage in mink are consistent with the presence of only a single strain of TME, the DY strain, capable of inducing accumulation of PrP(TME) in the lymphoid tissues of mink but not in hamsters. Thus, mink are a relevant animal model for further study of this unique strain, which ultimately may have been introduced through consumption of a TSE of ruminant origin.

Polarized X-ray scattering reveals non-crystalline orientational ordering in organic films

Molecular orientation critically influences the mechanical, chemical, optical and electronic properties of organic materials. So far, molecular-scale ordering in soft matter could be characterized with X-ray or electron microscopy techniques only if the sample exhibited sufficient crystallinity. Here, we show that the resonant scattering of polarized soft X-rays (P-SoXS) by molecular orbitals is not limited by crystallinity and that it can be used to probe molecular orientation down to size scales of 10 nm. We first apply the technique on highly crystalline small-molecule thin films and subsequently use its high sensitivity to probe the impact of liquid-crystalline ordering on charge mobility in polymeric transistors. P-SoXS also reveals scattering anisotropy in amorphous domains of all-polymer organic solar cells where interfacial interactions pattern orientational alignment in the matrix phase, which probably plays an important role in the photophysics. The energy and q-dependence of the scattering anisotropy allows the identification of the composition and the degree of orientational order in the domains.

Soft x-ray scattering facility at the Advanced Light Source with real-time data processing and analysis

We present the development and characterization of a dedicated resonant soft x-ray scattering facility. Capable of operation over a wide energy range, the beamline and endstation are primarily used for scattering from soft matter systems around the carbon K-edge (∼285 eV). We describe the specialized design of the instrument and characteristics of the beamline. Operational characteristics of immediate interest to users such as polarization control, degree of higher harmonic spectral contamination, and detector noise are delineated. Of special interest is the development of a higher harmonic rejection system that improves the spectral purity of the x-ray beam. Special software and a user-friendly interface have been implemented to allow real-time data processing and preliminary data analysis simultaneous with data acquisition.

Efficiency and its bounds for thermal engines at maximum power using Newton's law of cooling

We study a thermal engine model for which Newton's cooling law is obeyed during heat transfer processes. The thermal efficiency and its bounds at maximum output power are derived and discussed. This model, though quite simple, can be applied not only to Carnot engines but also to four other types of engines. For the long thermal contact time limit, new bounds, tighter than what were known before, are obtained. In this case, this model can simulate Otto, Joule-Brayton, Diesel, and Atkinson engines. While in the short contact time limit, which corresponds to the Carnot cycle, the same efficiency bounds as that from Esposito et al. [Phys. Rev. Lett. 105, 150603 (2010)] are derived. In both cases, the thermal efficiency decreases as the ratio between the heat capacities of the working medium during heating and cooling stages increases. This might provide instructions for designing real engines.

Microbial degradation of microcystin-LR by Ralstonia solanacearum

A bacterial strain was isolated from Lake Dianchi (China) and its degradability and degradative pathways of the cyanobacterial toxin microcystin-LR (MC-LR) were studied. On the basis of morphological, physiological and biochemical tests, the strain was identified as Ralstonia solanacearum. The acute oral toxicity tests showed that Ralstonia solanacearum belongs to a non-toxic class. This bacterium degraded MC-LR at the rate of 9.4 mg/L per day, which was higher than those of the other bacterial strains reported in the literature. As for the degradative pathways, the results showed that the Adda-Arg peptide bond of MC-LR was initially hydrolysed by Ralstonia solanacearum to form a linear molecule as an intermediate. The intermediate product subsequently underwent a cyclisation reaction via dehydration to form a final product with a small peptide ring at one end of the molecule. These biodegradative pathways were different from those reported with other bacterial strains, suggesting that MC-LR may undergo different transformations, and different products were formed due to different compositions of bacteria present in natural lakes and reservoirs. These results suggest that there is a significant potential for Ralstonia solanacearum as a degrader for MC-LR removal from wastewater.