Population-specific recombination sites within the human MHC region

Genetic rearrangement by recombination is one of the major driving forces for genome evolution, and recombination is known to occur in non-random, discreet recombination sites within the genome. Mapping of recombination sites has proved to be difficult, particularly, in the human MHC region that is complicated by both population variation and highly polymorphic HLA genes. To overcome these problems, HLA-typed individuals from three representative populations: Asian, European and African were used to generate phased HLA haplotypes. Extended haplotype homozygosity (EHH) plots constructed from the phased haplotype data revealed discreet EHH drops corresponding to recombination events and these signatures were observed to be different for each population. Surprisingly, the majority of recombination sites detected are unique to each population, rather than being common. Unique recombination sites account for 56.8% (21/37 of total sites) in the Asian cohort, 50.0% (15/30 sites) in Europeans and 63.2% (24/38 sites) in Africans. Validation carried out at a known sperm typing recombination site of 45 kb (HLA-F-telomeric) showed that EHH was an efficient method to narrow the recombination region to 826 bp, and this was further refined to 660 bp by resequencing. This approach significantly enhanced mapping of the genomic architecture within the human MHC, and will be useful in studies to identify disease risk genes.

Nonlocal dark solitons under competing cubic-quintic nonlinearities

We investigate properties of dark solitons under competing nonlocal cubic-local quintic nonlinearities. Analytical results, based on a variational approach and confirmed by direct numerical simulations, reveal the existence of a unique dark soliton solutions with their width being independent of the degree of nonlocality, due to the competing cubic-quintic nonlinearities.

Human papillomavirus infections in women with clinical gynaecological diseases in southwest China

The aim of this study was to determine the prevalence of human papillomavirus (HPV) infections in women with different gynaecological diseases (GDs) and ages in southwest China. With the assay of reverse dot blot, a total of 5544 cervical samples, including 1008 normal and 4536 abnormal specimens from women with GDs, were assayed for HPV detection. For the normal group, 20.2% (204/1008) tested positive for HPV, of which 40.2% (82/204) were high-risk (HR-HPV) genotypes. In the 4536 abnormal samples, 1569 women (34.6%) tested positive for HPV: 73.5% (1153/1569) had a single infection, 17.7% (277/1569) dual infection and 8.8% (138/1569) multiple HPV infection. Of 1569 HPV-positive specimens, 58.7% (921/1569) were infected with only HR-HPV genotypes. Significant differences in HPV infections were found among women of different ages (P < 0.01), number of pregnancies (P < 0.01), GDs (P < 0.01) and age at first sex (P < 0.01). In the present study, we found a high prevalence of HPV infection in women with GDs in southwest China. In addition to HPV types 16 and 18, a significant proportion of other HR-HPV genotypes were detected in this population.

Leukemia-related chromosomal loss detected in hematopoietic progenitor cells of benzene-exposed workers

Benzene exposure causes acute myeloid leukemia and hematotoxicity, shown as suppression of mature blood and myeloid progenitor cell numbers. As the leukemia-related aneuploidies monosomy 7 and trisomy 8 previously had been detected in the mature peripheral blood cells of exposed workers, we hypothesized that benzene could cause leukemia through the induction of these aneuploidies in hematopoietic stem and progenitor cells. We measured loss and gain of chromosomes 7 and 8 by fluorescence in situ hybridization in interphase colony-forming unit-granulocyte-macrophage (CFU-GM) cells cultured from otherwise healthy benzene-exposed (n=28) and unexposed (n=14) workers. CFU-GM monosomy 7 and 8 levels (but not trisomy) were significantly increased in subjects exposed to benzene overall, compared with levels in the control subjects (P=0.0055 and P=0.0034, respectively). Levels of monosomy 7 and 8 were significantly increased in subjects exposed to <10 p.p.m. (20%, P=0.0419 and 28%, P=0.0056, respectively) and ≥ 10 p.p.m. (48%, P=0.0045 and 32%, 0.0354) benzene, compared with controls, and significant exposure-response trends were detected (P(trend)=0.0033 and 0.0057). These data show that monosomies 7 and 8 are produced in a dose-dependent manner in the blood progenitor cells of workers exposed to benzene, and may be mechanistically relevant biomarkers of early effect for benzene and other leukemogens.

Characterization of 236 novel alleles at the HLA-A, -B, -C, -DRB1, -DQB1 and -DPB1 loci from China Marrow Donor Program

Two hundred and thirty-six novel human leukocyte antigen (HLA) alleles are described from volunteer donors of the China Marrow Donor Program: 71 HLA-A alleles, 79 HLA-B alleles, 43 HLA-C, 16 HLA-DRB1 alleles, 26 HLA-DQB1 and 1 HLA-DPB1. Two hundred and thirteen (90.3%) of the 236 novel alleles are single nucleotide substitution variants when compared with their most homologous allele. Seventy-eight of these single nucleotide variants are silent substitutions. The remaining novel alleles differ from their most similar allele by two to four nucleotide substitutions. Some of the novel alleles encode amino acid changes at positions not previously reported to be polymorphic, such as codons 57, 62, 67, 41 and 52 in HLA-A alleles; codons 133, 156, 201 and 215 in HLA-B alleles; codons 74, 208 and 225 in HLA-C; codons 25, 32 and 72 in HLA-DRB1; codons 20, 39 and 77 in HLA-DQB1.

Association between corneal biomechanical properties and myopia in Chinese subjects

PURPOSE

To examine the relationship between corneal biomechanical properties and the degree of myopia.

METHODS

Chinese subjects (n=172, age: 11-65 years) were divided into diagnostic groups with non-myopia (spherical equivalence (SE)>-0.50 D), low (-3.00 ≤ SE ≤ -0.50 D), moderate (-6.00 ≤ SE < -3.00 D), and high myopia (SE<-6.00 D). Only the right eye of each subject was analyzed. Central corneal thickness (CCT) was measured by optical coherence tomography. An ocular response analyzer was used to measure corneal hysteresis (CH), corneal resistance factor (CRF), intraocular pressure (IOP), and corneal compensated IOP (IOPcc). Refraction was measured by both automated and subjective refractometry and expressed as SE.

RESULTS

CH was significantly lower in high myopia compared with both low and non-myopia (P ≤ 0.002). CCT was 1.5 times more correlated to CH variation compared with refraction. Similarly, CRF was four times more dependent on CCT than refraction. CH (P<0.001) or CRF (P=0.005) was positively correlated to refraction. Both IOP and IOPcc were negatively correlated to refraction (P<0.001), respectively.

CONCLUSIONS

CH decreases only in high myopia. Refraction is positively correlated to both CH and CRF but negatively correlated to both IOP and IOPcc. These results indicate that the mechanical strength in anterior segment of the eye is compromised in high myopia. In addition, high myopia may increase the risk of glaucoma.

Degradation of surfactant wastewater under microwave irradiation in the presence of activated carbon assisted with nano-sized TiO2 or nano-sized ZnO

An improved method treating surfactant wastewater by the addition of semiconductor material such as nano-sized TiO2 or ZnO to activated carbon (AC) with microwave (MW) irradiation was proposed so as to assist efficient degradation of organic pollutants. A series of degradation experiments of sodium dodecyl benzene sulfonate (SDBS) were carried out under MW irradiation in the presence of AC/TiO2 or AC/ZnO. The influences of catalyst dose, irradiation time, initial SDBS concentration and solution acidity on the degradation were assessed in detail. The results showed that the addition of TiO2 or ZnO obviously promoted the degradation and AC/TiO2 system displayed higher catalytic activity under MW irradiation. Thus the method of MW irradiation with AC/TiO2 or AC/ZnO revealed many advantages of rapid degradation rate, short irradiation time, low cost, no residual intermediates and no secondary pollution in applications.

Microfluidic protein preconcentrator using a microchannel-integrated nafion strip: experiment and modeling

We propose a simple microfluidic device for protein preconcentration based on the electrokinetic trapping principle. It comprises a narrow Nafion strip that is simply cut from a commercial membrane and is integrated into a molded poly(dimethylsiloxane) (PDMS) microfluidic structure using a guiding channel. Mechanically clamping the PDMS/Nafion assembly with a glass substrate results in a rapid prototypable, leak-tight, and easily disposable device. Our device preconcentrates negatively charged fluorescent proteins located at the anodic microfluidic compartment side of the Nafion strip within a few minutes and up to a concentration factor of 10(4). Moreover, we present a numerical study of the preconcentration effect by solving the coupled Poisson, Nernst-Planck, and Navier-Stokes equations for our type of device, which provides microscopic insight into the mechanism of preconcentration. The electrical field across the ion-permselective Nafion generates concentration polarization, i.e., ion depletion at the anodic side and ion enrichment at the cathodic side for both types of ions, with a local excess of mobile positive ions in the depleted concentration polarization zone, inducing a nonequilibrium electrical double layer in close proximity to the Nafion membrane. A voltage difference applied over the anodic compartment is used to generate the electrophoretic flow velocity of the negatively charged tracer biomolecules. This, in combination with the electroosmotic flow in the opposite direction, which originates from the fixed charges on the channel walls and the induced space charge near the membrane, provides the basis for the local preconcentration of the negative tracer biomolecules.

Identification of a novel HLA-C allele, HLA-C*03:85, in a Singaporean Chinese

HLA-C*03:85 differs from C*03:03:01 by a single nucleotide substitution at position 276, in exon 2.

Non-fatal injury rates among the "left-behind children" of rural China

OBJECTIVE

To investigate patterns of non-fatal unintentional injuries among "left-behind children" in Macheng, China.

METHODS

A cross-sectional survey was conducted in September and October, 2006. Age-specific and sex-specific injury rates were calculated.

RESULTS

3019 students were interviewed in six schools. Of these, 1182 were identified as "left-behind"; 62.3% had both parents away from home, and 37.7% had one parent away from home. The annual injury rate per 1000 among left-behind children was more than twice that of children living with both parents: 252.9 (95% CI 233.0 to 273.0) and 119.8 (95% CI 105 to 134), respectively. Male left-behind children had the highest annual injury rate: 316.4 (95% CI 295 to 338) per 1000. The three leading external causes of injury were similar for both groups of children: falls (33.8%); mechanical injuries (16.2%); and animal bites (14.5%).The location where injuries occurred were home (32.0%), school (26.0%) and roadways (23.9%) for left-behind children. There were no significant associations between the identified guardian and injury mechanism.

CONCLUSIONS

A large proportion of students in the schools of rural Macheng are left-behind children. Left-behind children have a higher injury rate than those in the care of both parents. This may be important in the development of injury prevention strategies in rural communities in China.

Differential effects of smoking on lung cancer mortality before and after household stove improvement in Xuanwei, China

Background:

In Xuanwei County, Yunnan Province, China, lung cancer mortality rates in both males and females are among the highest in China.

Methods:

We evaluated differential effects of smoking on lung cancer mortality before and after household stove improvement with chimney to reduce exposure to smoky coal emissions in the unique cohort in Xuanwei, China. Effects of independent variables on lung cancer mortality were measured as hazard ratios and 95% confidence intervals using a multivariable Cox regression model that included separate time-dependent variables for smoking duration (years) before and after stove improvement.

Results and conclusion:

We found that the effect of smoking on lung cancer risk becomes considerably stronger after chimney installation and consequent reduction of indoor coal smoke exposure.

Diffuse alveolar hemorrhage in systemic lupus erythematosus: a retrospective study in China

The objective of this study was to determine the clinical features of systemic lupus erythematosus (SLE) patients with diffuse alveolar hemorrhage (DAH). The medical records of 29 patients with DAH among 2133 SLE patients admitted to Peking Union Medical College Hospital from January 2004 to January 2009 were reviewed in this retrospective study. It was found that hypoxemia (100%), dyspnea (90%), cough (79%) and fever (72%), rather than hemoptysis (66%), were the most common symptoms. The most common extrapulmonary presentation was renal involvement (90%). In about 60% of patients nosocomial infection was also present. The mean drop in hemoglobin was 32 ± 10.9 g/l. Mean Systemic Lupus Erythematosus Disease Activity Index (SLEDAI) was 17 ± 9. All patients received high-dose corticosteroid therapy and most were also given immunosuppressive agents. Rates of concomitant nosocomial infection and mechanical ventilation in non-survivors were higher than those of survivors (p < 0.05). DAH is a rare and catastrophic event in SLE. DAH can occur at any stage of the disease course; it usually occurs in patients with active SLE, and is frequently complicated by lupus nephritis. Some patients may have no hemoptysis. Early aggressive management with high-dose steroids and cyclophosphamide is advocated.

Association between genetic variants in VEGF, ERCC3 and occupational benzene haematotoxicity

INTRODUCTION

Benzene is an established human haematotoxin, with substantial interindividual variation in benzene-induced toxicity.

METHODS

To further examine if genetic variation contributes to benzene haematotoxicity, we analysed 1023 tagSNPs in 121 gene regions important for benzene metabolism, haematopoiesis, leukaemia and lymphoma among 250 workers exposed to benzene and 140 unexposed controls in a cross-sectional study carried out in China. Linear regression was used to analyse the relationship between genetic polymorphisms and total white blood cell (WBC) count and its subtypes, adjusting for potential confounders and occupational exposure to benzene and toluene among exposed workers. The minp test assessed the association on the gene region level. The false discovery rate method was used to control for multiple comparisons.

RESULTS

VEGF (minp = 0.0030) and ERCC3 (minp = 0.0042) were the most significantly associated gene regions with altered WBC counts among benzene-exposed workers, after accounting for multiple comparisons. Highly significant changes were also found for WBC subtype counts, including granulocytes, CD4+ T cells and lymphocytes for VEGF and granulocytes and NK cells for ERCC3. Further, in workers exposed to <1 ppm, a SNP in VEGF was associated with changes in WBC and granulocyte counts, and SNPs in ERCC3 were associated with changes in WBC, NK cell and granulocyte counts.

DISCUSSION

Our findings suggest that genetic variation in VEGF, which plays an important role in blood vessel growth, and ERCC3, which is a member of the DNA repair pathway and is responsible for repairing bulky DNA adducts formed by chemicals, may contribute to individual susceptibility to benzene-induced haematotoxicity at relatively low levels of benzene exposure.