Frequency of the mtDNA 9-bp deletion in Chinese ethnic groups

The 9-bp deletion in the COII/tRNA(Lys) intergenic region (region V) of human mitochondrial DNA was screened in 1521 Chinese from 16 ethnic groups and 9 Hen geographic groups. The highest frequency was found in populations of Miao (32.4%) and Bouyei (30.8

Different matrilineal contributions to genetic structure of ethnic groups in the Silk Road region in China

Previous studies have shown that there were extensive genetic admixtures in the Silk Road region. In the present study, we analyzed 252 mtDNAs of five ethnic groups (Uygur, Uzbek, Kazak, Mongolian, and Hui) from Xinjiang Province, China (through which the

Evolutionary history of the mtDNA 9-bp deletion in Chinese populations and its relevance to the peopling of east and southeast Asia

In total, 1218 Chinese from twelve ethnic groups and nine Han geographic groups were screened for the mtDNA 9-bp deletion motif. The frequency of the 9-bp deletion in all samples was 14.7% but ranged from 0% to 32% in the various ethnic groups. Three individuals had a triplication of the 9-bp segment. Phylogenetic and demographic analyses of the mtDNA hypervariable segment 1 (HVS1) sequences suggest that the 9-bp deletion occurred more than once in China. The majority of the Chinese deletion:haplotypes (about 90%) have a common origin as a mutational event following an initial expansion of modem humans in eastern Asia. Other deletion haplotypes and the three haplotypes with a 9-bp triplication may have arisen independently in the Chinese, presumably by replication error. HVS1 haplotype analysis suggests two possible migration routes of the 9-bp deletion in east and southeast Asia. Both migrations originated in China with one route leading to the Pacific Islands via Taiwan, the other to southeast Asia and possibly the Nicobar Islands. Along both routes of peopling, a decrease in HVS1 diversity of the mtDNA haplotypes is observed. The "Polynesian motif (16217T/C, 16247A/G, and 16261C/T)" and the 16140T/C, 16266C/A, or C/G polymorphisms appear specific to each migration route.

Thermoplastic Elastomers Based on Compatibilized Poly(butylene terephthalate) Blends: Effect of Functional Groups and Dynamic Curing

Two sets of graft copolymers were prepared by grafting glycidyl methacrylate (GMA) or ally] (3-isocyanate-4-tolyl) carbamate (TAI) onto ethylene/propylene/diene terpolymer (EPDM) in an internal mixer. These graft copolymers were used as the compatibilizer to prepare the thermoplastic elastomers (TPEs) containing 50 wt%, of poly(butylene terephthalate), PBT, 30 wt% of compatibilizer, and 20 wt% of nitrile-butadiene rubber, NBR. The indirect, two-step mixer process was chosen for dynamic curing.

Novel aliphatic poly(ester-carhonate) with pendant allyl ester groups and its folic acid functionalization

A series of novel poly(ester-carbonate)s bearing pendant allyl ester groups P(LA-co-MAC)s were prepared by ring-opening copolymerization Of L-lactide (LA) and 5-methyl-5-allyloxycarbonyl-1,3-dioxan-2-one (MAC) with diethyl zinc (ZnEt2) as initiator. NMR analysis investigated the microstructure of the copolymer. DSC results indicated that the copolymers displayed a single glass-transition temperature (T-g), which was indicative of a random copolymer, and the Tg decreased with increasing carbonate content in the copolymer.

Aliphatic Poly(ester-carbonate)s Bearing Amino Groups and Its RGD Peptide Grafting

This article deals with (1) synthesis of novel cyclic carbonate monomer (2-oxo [1,3]dioxan-5-yl)carbamic acid benzyl ester (CAB) containing protected amino groups; (2) ring-opening copolymerization of the cyclic monomer with L-lactide (LA) to provide novel degradable poly(ester-carbonate)s with functional groups; (3) removal of the protective benzyloxycarbonyl (Cbz) groups by catalytic hydrogenation to afford the corresponding poly(ester-co-carbonate)s with free amino groups; (4) grafting of oligopeptide Gly-Arg-Gly-Asp-Ser-Tyr (GRGDSY, abbreviated as RGD) onto the copolymer pendant amino groups in the presence of 1,1'-carbonyldiimidazole (CDI).

Synthesis and characterization of titanium complexes bearing two beta-enaminoketonato ligands with electron-withdrawing groups and their behavior in ethylene polymerization

A series of new titanium complexes with two asymmetric bidentate beta-enaminoketonato (N,O) ligands (4b-t), [RN=CCF3)CHC(t-BU)O](2)TiCl2 (4b, R = -C6H4F(o); 4c, R = -C6H4F(m);4d, R = -C6H4F(p); 4e, R = - C6H3F2(2,3); 4f, R = -C6H3F2(2,4); 4g, R = -C6H3F2(2,5); 4h, R = -C6H3F2(2,6); 4i, R = -C6H3F2(3,4); 4j, R = -C6H3F2(3,5); 4k, R = -C6H2F3(2,3,4); 4l, R = -C6H2F3(3,4,5); 4m, R = -C6H4CF3(o); 4n, R =-C6H4CF3(m); 4o, R = -C6H4CF3(p); 4p, R = -C6H4Cl(p); 4q, R = -C6H4I(p); 4r, R = -C6H4NO2(P); 4s, R = -CH2C6H5; 4t, R = -C6H11), have been synthesized and characterized.

Synthesis and polymerization of some macrocyclic (arylene ether sulfone) containing cardo groups and macrocyclic (arylene ether ketone sulfone) oligomers

Some novel macrocyclic (arylene ether sulfone) containing cardo groups and (arylene ether ketone sulfone) oligomers have been synthesized in high yields by a nucleophilic aromatic substitution reaction of 4,4'-difluorophenylsulfone with bisphenols in the presence of anhydrous potassium carbonate under a pseudo-high-dilution condition. Detailed structural characterization of these oligomers by matrix-assisted laser desorption/ionization-time of flight-mass spectrometry (MALDI-TOF-MS), fast atom bombardment mass spectrometry (f.a.b.-m.s.), nuclear magnetic resonance spectrometry (n.m.r.) and single-crystal X-ray structure analysis confirms their cyclic nature, and the composition of the oligomeric mixtures is provided by g.p.c. analysis. Ring polymerization of cyclic oligomers 3a to a high molecular weight polymer with M-w of 59.1 k was achieved by heating at 290 degrees C for 40 min in the presence of a nucleophilic initiator. (C) 1998 Elsevier Science Ltd. All rights reserved.

Synthesis of a series of chiral copolymers with azo groups and investigations of reversible liquid crystalline alignment induced by the LB films of these materials

A series of liquid crystalline copolymers, poly{2-hydroxyethyl methacrylate}-co-{6-[4-(S-2-methyl-1-butyloxycarbonylphenylazo)phenoxy]hexyl methacrylate} with an azobenzene moiety as photoreactive mesogenic unit, was prepared and investigated by using DSC, polarized optical microscopy and X-ray diffraction. The results show that these polymers exhibit smectic phases. Z-type Langmuir-Blodgett films of these copolymers were successfully deposited onto calcium fluoride and quartz. Reversible homeotropic and planar liquid crystal alignments were induced by using the photochromism of the LB films of one of the copolymers containing 20.6 mol % of the azo unit.

Distribution of CCR2-64I and SDF1-3 ' A alleles and HIV status in 7 ethnic populations of Cameroon

Limited information is available on the prevalence among rural Africans of host genetic polymorphisms conferring resistance to HIV-1 infection or slowing HIV disease progression.We report the allelic frequencies of the AIDS-related polymorphisms CCR2-64I, SDF1-3#A, and CCR5-D32 in 321 volunteers from 7 ethnic groups in Cameroon. Allelic frequencies differed among the 7 ethnic groups, ranging from 10.8% to 31.3% for CCR2-64I and 0.0% to 7.1% for SDF1-3#A. No CCR5-D32 alleles were found. HIV seroprevalence was 6.9% in the total population and peaked at younger ages in girls and women than in boys and men. Among 15- to 54-year-olds, HIV seroprevalence varied from 2.0% to 11.1% among the village populations. Conditional logistic regression analysis using data from boys and men aged 15 to 54 years showed the number of CCR2-64I alleles to be a significant risk factor for HIV seropositivity (odds ratio per allele adjusted for age and matched on ethnic group = 6.3, 95% confidence interval: 1.3–30.3); this association was not found in women. The findings are consistent with the hypothesis that CCR2-64I alleles may delay HIV disease progression without affecting susceptibility to infection among men. We did not observe this relation among women, and other factors, such as multiple pregnancies or maternal stressors (eg, breastfeeding), may have masked any protective effect of CCR2-64I alleles. Further study of this issue among women is warranted. SDF1-3#A did not differ between HIV-seropositive and HIV-seronegative individuals but wasassociated with increasing age among HIV-seronegative women, suggesting a protective effect against HIV-1 infection.

Length polymorphism of thymidylate synthase regulatory region in Chinese populations and evolution of the novel alleles

The tandemly repeated 28-bp sequence in the 5'-terminal regulatory, region of human thymidylate synthase (TSER), which has been reported to be polymorphic in different populations, was surveyed in 668 Chinese from 9 Han groups, 8 ethnic populations, and 3

High prevalence of HIV-1 and hepatitis C virus coinfection among injection drug users in the southeastern region of Yunnan, China

The southeastern region of Yunnan province is a key site for drug trafficking and HIV-1 infection spread from the west of Yunnan and Laos to southeastern China. To investigate the prevalence of HIV-1 infection and hepatitis C virus (HCV) coinfection among injection drug users (IDUs) in southeastern Yunnan, three cohorts of 285 addicts, including 242 IDUs and 43 oral drug users, living in the cities of Gejiu and Kaiyuan and the county of Yanshan were studied. HIV-1 and HCV infections were detected by enzyme-linked immunosorbent assay and/or polymerase chain reaction. Data on the age, sex, risk behavior, drug use history, employment, ethnic background, and marriage status were obtained by interview. The overall prevalence of HIV-1 infection was 71.9%. The rate of HCV coinfection among 138 HIV-1-infected IDUs was 99.3%. Most HIV-infected IDUs were 20 to 35 years old (86.7%) and were ethnic Han (75.9%), suggesting that the epidemic in Yunnan is no longer confined to non-Han ethnic minorities, HIV prevalence in female IDUs (81.2%) was significantly higher than in male IDUs (68.2%) (p <.05). The prevalence of HIV infection reached 68.4% after 1 year of injection drug use. Needle/syringe sharing is the major high risk factor for the spread of HIV-1 and HCV infections. Large-scale educational campaigns are urgently needed to reduce the spread of HIV and HCV infection in these regions.

Nonlinear optical properties of (B3O7)(5-) and (B3O6)(3-) groups

From the chemical bond viewpoint, LiB3O5 (LBO) crystal has been studied by using the bond valence theory of complex crystals. Chemical bond parameters and linear and nonlinear optical (NLO) properties of each type of constituent chemical bonds are quantitatively determined. Because of the different crystal structure characteristics of LBO from those of beta-BaB2O4 (BBO), the two anionic groups, (B3O7)(5-) in LBO and (B3O6)(3-) in BBO, play different roles in contributions to their own total NLO tensor coefficients of LBO and BBO, respectively. By comparison, we find that planar (B3O6)(3-) groups are the ideal structure model, leading to little cancellation of contributions of each kind of bond in these groups, and this gives us a useful guide to design new NLO materials in the future.

Classified one-step modified signed-digit arithmetic and its optical implementation

Based on the two-step modified signed-digit (MSD) algorithm, we present a one-step algorithm for the parallel addition and subtraction of two MSD numbers. This algorithm is reached by classifying the three neighboring digit pairs into 10 groups and then making a decision on the groups. It has only a look-up truth table, and can be further formulated by eight computation rules. A joint spatial encoding technique is developed to represent both the input data and the computation rules. Furthermore, an optical correlation architecture is suggested to implement the MSD adder in parallel. An experimental demonstration is also given. (C) 1996 Society of Photo-Optical instrumentation Engineers.