Propagation dynamics of an optical vortex imposed on an Airy beam

In this Letter, we demonstrate the general propagation dynamics of an Airy beam (AiB) carrying unit phase singularity, i.e., optical vortices (OVs). For the OV with a unit charge, theoretical analysis indicates that the OV carried by the AiB will propagate along the parabolic trajectory with an acceleration velocity twice as fast as conventional AiBs before a critical position. Thereafter, the AiB main lobe destroyed by OV will be reconstructed and the phase singularity will reappear in the middle of the AiB profile.

Enhanced thermal stability of monodispersed silver cluster arrays assembled on block copolymer scaffolds

Triblock copolymer poly(styrene-b-butadiene-b-styrene) (SBS) films with long-range ordered self-assembled nanopatterns are used as templates to selectively adsorb soft-landing silver clusters. Closely spaced cluster arrays with high monodispersity are formed through the confinement of the block copolymer scaffolds, and show a much enhanced thermal stability as compared with the cluster assemblies on the surfaces of covalent amorphous solids, or even on the disordered SBS films. Their morphologies are barely influenced by long time thermal annealing at a temperature as high as 180 degrees C, while in the latter case intense aggregations and coalescences of silver clusters are commonly observed upon annealing. The different thermal stabilities of the cluster assemblies also induce different evolutions of their optical extinction spectra under annealing. This promises a simple way to control the monodispersity and thermal stability of metal cluster assembly via self-assembled block copolymer template.

Simultaneous detection of enteric bacteria from surface waters by QPCR in comparison with conventional bacterial indicators

A rapid quantitative polymerase chain reaction (QPCR) method was developed for simultaneous detection of enteric bacteria from surface waters by utilizing a pair of universal primers which targeted four bacteria strains, namely Shigella dysenteriae, Vibrio cholerae, Salmonella typhimurium, and Escherichia coli. It was estimated that the QPCR method had a 94% confidence, and a detection limit as 2.7 E. coli cells per sample in undiluted DNA extracts. The QPCR method was applied for the bacteriological examination of several surface waters in the urban area of Xi'an, China and comparison was made with the conventional bacteria indicators determined by conventional membrane filter (MF) method. As a result, the calibrator cell equivalents (CCE) determined by QPCR was 2.2 to five times of the total coliform CFU, and the characteristics of the bacterial quality of different waters could be well presented by the QPCR results with a higher sensitivity. The coefficient of variation (CV) of data obtained by QPCR was smaller than that by traditional MF method, indicating a more stable analysis result. The QPCR method could thus be used as a supplement of the conventional culture method for more sensitive detection of pathogenic enteric bacteria from water.

Airy beams generated by a binary phase element made of polymer-dispersed liquid crystals

Using polymer-dispersed liquid crystals (PDLCs), an electrically switchable binary phase pattern was fabricated to generate Airy beams through a programmable lithographic system. The right main lobe of the reconstructed Airy beam experienced 1.3 mm transverse deflection within 24 cm propagation distance. With a suitable voltage applied, the binary PDLC pattern can be erased due to the index match between polymers and liquid crystals. This versatile approach can be also used to generate other special beams with electrically tunable capability.

Thermal characteristics of microwave ablation in the vicinity of an arterial bifurcation

PURPOSE

The objective of this research was to reveal the thermal characteristics of microwave ablations in the vicinity of an arterial bifurcation.

METHODS

The temperature distribution after microwave heating of a liver-like material in the close proximity of an arterial bifurcation was simulated using the finite element method. Coupled fluid flow and solid heat transfer were taken into consideration and a three-dimensional analysis was performed. An experimentally determined SAR (specific absorption rate) generated by the absorption of microwaves in liver-like material was used in the analysis instead of utilizing electromagnetic calculations. Several different tests of time-controlled ablations with varying distances between the microwave antenna and the bifurcation were performed and detailed temperature distributions near the bifurcation were obtained.

RESULTS

The interaction between the recirculation flow in the bifurcation and the heat transfer in the surrounding tissue makes the temperature distribution near the bifurcation complicated. Most importantly, after a period of continuous heating with constant microwave output power, the maximum temperatures caused by the ablation did not always increase with the distance between the antenna and the bifurcation.

CONCLUSION

It can be concluded that inadequate ablations can be the result not only from a close proximity between the antenna and the blood vessel, but also from a complicated blood flow in large vessels whose structure causes recirculation flow.

Electrically switchable computer-generated hologram using a liquid crystal cell with a proton beam patterned polymethylmethacrylate substrate

An electrically switchable computer-generated hologram (CGH) was fabricated using a liquid crystal (LC) cell. A polymethylmethacrylate (PMMA) film, which was spin-coated on one glass substrate of the LC cell, was patterned by a focused 2 MeV proton beam with a CGH phase pattern (2 microm resolution). With an applied voltage on the LC cell CGH sample, an index modulation was produced between the regions with and without PMMA because of the reorientation of LC molecules under the external electric field. The maximum diffraction efficiency measured was about 28.7%. The operating voltage was below 15 V(rms).

Bacterial communities in a crude oil gathering and transferring system (China)

Bacterial communities in crude oil and oil field production water samples from an oil gathering and transferring system in Changqing Oil field in China were investigated by 16S rRNA denaturing gradient gel electrophoresis (DGGE) analysis followed by gene cloning and sequencing. DGGE profiles showed that bacterial communities are far more rich in the water samples than that in the crude oil samples, and that bacteria related to Ochrobactrum sp. and Stenotrophomonas sp. were detected in all crude oil and oil field water samples. Bacteria related to Burkholderia sp., Brevundimonas sp., and Propionibacterium sp. were detected in the crude oil samples but not in water samples. Bacteria related to Hippea sp., Acidovorax sp., Arcobacter sp., Pseudomonas sp., Thiomicrospira sp., Brevibacterium sp., Tissierella sp. and Peptostreptococcus sp. were detected in the water samples but not in crude oil samples. Using an archaea-specific primer set, methanogens related to Methanomicrobials and Methanosarcinales were found in water samples but not in crude oil samples. The comparability of the microbial communities in the water and crude oil phase during the period of oil gathering and transferring process was 83.3% and 88.2%, respectively, indicating a stable structure of the microbial communities.

A negative-positive tunable liquid-crystal microlens array by printing

A tunable microlens array by printing was demonstrated. An UV-curable adhesive, NOA65, was printed and cured to form a lens array profile on an ITO glass. Then this microlens array ITO glass was assembled with a normal ITO glass to form a cell, which was later filled with a liquid crystal. The focal length of the lens array can be tuned by an electric field, which changes the index difference between liquid crystals and NOA65 due to the reorientation of the LC molecules. In our experiment, the focal length varied from -2.29 cm to 3.12 cm when the applied voltage was increased from 0 V to 13.26 V.

Effects of dietary phospholipid level in cobia (Rachycentron canadum) larvae: growth, survival, plasma lipids and enzymes of lipid metabolism

A study was conducted to determine the effects of dietary phospholipid (PL) levels in cobia (Rachycentron canadum) larvae with regard to growth, survival, plasma lipids and enzymes of lipid metabolism. Fish with an average weight of 0.4 g were fed diets containing four levels of PL (0, 20, 40 and 80 g kg(-1)dry matter: purity 97%) for 42 days. Final body weight (FBW), weight gain (WG) and survival ratio were highest in the 8% PL diet group and mortality was highest in PL-free diet group. We examined the activities of lipoprotein lipase (LPL) and hepatic lipase (HL) in liver, lecithin-cholesterolacyltransferase (LCAT) in plasma as well as plasma lipids and lipoprotein. LCAT activity showed a decrease of more than two-fold in PL-supplemented diet groups compared with the PL-free diet group. HL activity was highest in the 8% PL diet group and the other three groups showed no difference. LPL activity was significantly higher in the PL-supplemented diet groups than in the PL-free diet group. The dietary intervention significantly increased plasma phospholipids and total cholesterol (TC) levels, and the higher free cholesterol (FC) level contributed to the TC level. However, the fish fed PL exhibited a significantly decreased plasma triglyceride (TG) level. The lipoprotein fractions were also affected significantly by the PL. The PL-supplemented diet groups had significantly higher high-density lipoprotein (HDL) compared with the PL-free diet group, but showed a marked decrease in very low-density lipoprotein (VLDL). The results suggested that PL could modify plasma lipoprotein metabolism and lipid profile, and that the optimal dietary PL level may well exceed 80 g kg(-1) for cobia larvae according to growth and survival.

Characteristics of bacterial and viral contamination of urban waters: a case study in Xi'an, China

In order to gain knowledge on the presence of bacteria and viruses in urban waters, the authors started a long-term study on the microbiological quality of urban lakes and rivers in Xi'an, China. In the current study, enteroviruses were chosen as typical viruses and RT-nested PCR was conducted for their detection. Universal primers were designed for simultaneous detection of poliovirus, coxsackievirus, and enterovirus 71 which are the most frequently encountered enteroviruses in China. The RT-nested PCR protocol established in this study showed high sensitivity and specificity. The detection limit was equivalent to 0.038 CCID50 per litre by applying a modified adsorption-elution concentration method. No cross-reactivity was observed using the genome of pathogenic bacteria as of PCR template. The occurrence of enteroviruses was compared with fecal coliform count in a 6-month period from July to December 2006 for the urban waters. As a result, it was noticed that the presence of enteroviruses might not relate to the fecal coliform count so much. Statistical analysis also indicated that there was no significant correlation between the presence of enteroviruses and that of total bacteria, total coliform, and fecal coliform.

Electrically switchable optical vortex generated by a computer-generated hologram recorded in polymer-dispersed liquid crystals

A computer-generated hologram designed to generate an optical vortex was recorded in a cell filled with polymer-dispersed liquid crystal material under a collimated Ar+ laser beam operating at 514.5 nm. Owing to the photopolymerization-induced phase separation between the polymer and the liquid crystal, an index modulation was formed between the polymer-rich and liquid crystal-rich regions. A good optical vortex beam with high fidelity was reconstructed using a collimated He-Ne laser beam. The diffraction efficiency is estimated to be about 13%-17%. With a suitable voltage applied, the reconstructed optical vortex beam can be switched owing to the index change between the polymer and the liquid crystal.

Are the local blood oxygen level-dependent (BOLD) signals caused by neural stimulation response dependent on global BOLD signals induced by hypercapnia in the functional MR imaging experiment? Experiments of long-duration hypercapnia and multilevel carbon dioxide concentration

BACKGROUND AND PURPOSE

The relationship between the local blood oxygen level-dependent (BOLD) signals caused by neural stimulation (fBOLD) and the global BOLD signals induced by hypercapnia (hBOLD) has not been fully investigated. In this study, we examine whether fBOLD is modulated by hBOLD signals, by means of experiments using a relatively wide range of inhaled carbon dioxide (CO(2)) for a long duration of 5 minutes.

MATERIALS AND METHODS

Ten healthy volunteers were recruited, each undergoing 6 separate experiments by inhaling gas mixtures with different fractions of CO(2) (room air, 3%-7%). Each experiment contained 3 phases, prehypercapnic, hypercapnic, and posthypercapnic, during which boxcar visual stimulus was given. The local fBOLD signals were measured from areas showing activation patterns highly correlated with the visual stimulus paradigm, whereas the global hBOLD signals were measured from areas showing no visual activations. Percentage changes in fBOLD during transient-state hypercapnia and steady-state hypercapnia were both investigated in response to varying degrees of hypercapnic perturbations.

RESULTS

The hBOLD signals increased with increase of inhaled CO(2) fractions. The duration for the hBOLD signals to reach steady state prolonged with increase of inhaled CO(2) fractions. Normalized fBOLD ratio was inversely related to the inhaled CO(2) during steady-state hypercapnia but showed positive association with hBOLD during transient-state hypercapnia.

CONCLUSION

Our study concludes that the steady-state fBOLD signal intensity is dependent on and inversely related to the hBOLD signals. Previous reports documenting independent and additive relationships between hBOLD and fBOLD may likely be due to transient-state observations.

A new iterative algorithm to reconstruct the refractive index

The latest developments in x-ray imaging are associated with techniques based on the phase contrast. However, the image reconstruction procedures demand significant improvements of the traditional methods, and/or new algorithms have to be introduced to take advantage of the high contrast and sensitivity of the new experimental techniques. In this letter, an improved iterative reconstruction algorithm based on the maximum likelihood expectation maximization technique is presented and discussed in order to reconstruct the distribution of the refractive index from data collected by an analyzer-based imaging setup. The technique considered probes the partial derivative of the refractive index with respect to an axis lying in the meridional plane and perpendicular to the propagation direction. Computer simulations confirm the reliability of the proposed algorithm. In addition, the comparison between an analytical reconstruction algorithm and the iterative method has been also discussed together with the convergent characteristic of this latter algorithm. Finally, we will show how the proposed algorithm may be applied to reconstruct the distribution of the refractive index of an epoxy cylinder containing small air bubbles of about 300 micro of diameter.

No evidence of association of the osteocalcin gene HindIII polymorphism with bone mineral density in Chinese women

Osteoporosis is a major health problem, mainly characterized by low bone mineral density (BMD). Osteocalcin (also known as BGP, for bone Gla protein) is a significant biomarker of bone turnover and thus the BGP gene has been considered as an important candidate gene for osteoporosis. A few studies on the relationship between variants of the BGP gene and BMD variation, via traditional association and/or linkage methods, have yielded conflicting results. In the present study, we simultaneously tested linkage and/or association of the BGP HindIII polymorphism with BMD in a large cohort of pre-menopausal Chinese women. A total of 1,263 subjects from 402 Chinese nuclear families were examined. Each family consists of both parents and at least one daughter aged between 20-45 years. BMDs at the lumbar spine and hip were measured by dual-energy X-ray absorptiometry (DXA). Using the QTDT (quantitative transmission disequilibrium test) program, we did not detect significant evidence of linkage or association between the BGP HindIII polymorphisms and the BMD variation at any skeletal site. Our data do not support the BGP gene having a major effect on BMD variation in pre-menopausal Chinese women.

Contribution of AhyR to virulence of Aeromonas hydrophila J-1

Aeromonas hydrophila is a broad-host-range pathogen and its pathogenesis is multifactorial. A regulatory mechanism known as quorum sensing has been found to be involved in the regulation of virulence in many bacteria. In A. hydrophila the ahyR gene encodes LuxR-type response regulator. Here we describe the inactivation of the ahyR gene of A. hydrophila J-1 by the insertion of a DNA fragment containing a kanamycin resistance determinant and reintroduced by allelic exchange into the chromosome of A. hydrophila J-1 by means of the suicide plasmid pJP5603. Cytotoxic effects on EPC cells assay and LD(50) determinations in fish demonstrated that the ahyR mutant was highly attenuated relative to the wild-type strain. Compared with the parent strain, some characteristics, such as biochemical characters and outer membrane protein profiles, had changed. Some main virulent determinants could not be detected, including proteases, amylase, Dnase, hemolysin and S layer. This article confirmed the important function of AhyR in the pathogenesis of A. hydrophila J-1.

Fluidised pellet bed bioreactor: a promising technology for onsite wastewater treatment and reuse

A pilot-scale fluidised pellet bed (FPB) bioreactor, which combines chemical coagulation, biological degradation, particle pelletisation and separation in one unit, was applied for onsite wastewater treatment and reuse. As a result of rational use of inorganic coagulant and organic polymer and moderate mechanical agitation, spherical particles were generated in the upflow column and a well-fluidised bed was formed. With a continuous supply of dissolved oxygen through a recycling loop, an aerobic condition was kept in the bottom section of the FPB column. Under such conditions the pellets in the FPB column showed the following characteristics: (1) compact structure and high density; (2) rich in microorganisms; and (3) high MLSS and MLVSS concentrations. Therefore, the FPB bioreactor achieved more than 90% removal of SS, COD, BOD and TP from raw domestic wastewater within a total hydraulic retention time (HRT) of only about 30 minutes. It also showed nitrification and denitrification ability and the TN removal could be about 50% as the recycling ratio was increased to 1:1. The treated water quality is generally competitive with the secondary effluent from a conventional activated sludge process. With these advantages the FPB bioreactor is recommendable as a compact system for onsite wastewater treatment and reuse.

Gene profiling after knocking-down expression of nucleostemin in Hela cells using oligonucleotide DNA microarray

Nucleostemin (NS) is preferentially and exclusively expressed in the stem cells and cancer cells, but not in differentiated adult tissues and cells. NS is likely to take part in controlling the proliferation and differentiation switch in stem cells and progenitor cells. Its deregulation in cancer also contributes to the elevated proliferation and undifferentiation of cancer cells. However, the mechanisms by which NS helps to maintain both cancer and stem cells in undifferentiated state remain unclear. In this study, we carried out gene profilings using oligonucleotide DNA microarray after knocking down the expression of NS in Hela cells. Of the 21,329 genes, 200 genes were found differentially expressed in NS silenced Hela cells with > 2 fold ratio (either > 2 or < 0.5). Category analysis indicated these differential genes were mainly related with cancer pathogenesis, cell death, cell growth and proliferation. NS related gene pathway analysis suggested NS was mostly involved in the networks of cell cycle and differentiation controls. p53 may not be the only partner of NS in its regulated pathways. c-Myc may directly or indirectly interact with it to control the proliferation and differentiation switch in cancer cells. Our study provides a general view of the NS-target genes, and indicates the possible pathways in which NS plays its role in proliferation control.

Loss of the flagellum happened only once in the fungal lineage: phylogenetic structure of kingdom Fungi inferred from RNA polymerase II subunit genes

Background

At present, there is not a widely accepted consensus view regarding the phylogenetic structure of kingdom Fungi although two major phyla, Ascomycota and Basidiomycota, are clearly delineated. Regarding the lower fungi, Zygomycota and Chytridiomycota, a variety of proposals have been advanced. Microsporidia may or may not be fungi; the Glomales (vesicular-arbuscular mycorrhizal fungi) may or may not constitute a fifth fungal phylum, and the loss of the flagellum may have occurred either once or multiple times during fungal evolution. All of these issues are capable of being resolved by a molecular phylogenetic analysis which achieves strong statistical support for major branches. To date, no fungal phylogeny based upon molecular characters has satisfied this criterion.

Results

Using the translated amino acid sequences of the RPB1 and RPB2 genes, we have inferred a fungal phylogeny that consists largely of well-supported monophyletic phyla. Our major results, each with significant statistical support, are: (1) Microsporidia are sister to kingdom Fungi and are not members of Zygomycota; that is, Microsporidia and fungi originated from a common ancestor. (2) Chytridiomycota, the only fungal phylum having a developmental stage with a flagellum, is paraphyletic and is the basal lineage. (3) Zygomycota is monophyletic based upon sampling of Trichomycetes, Zygomycetes, and Glomales. (4) Zygomycota, Basidiomycota, and Ascomycota form a monophyletic group separate from Chytridiomycota. (5) Basidiomycota and Ascomycota are monophyletic sister groups.

Conclusion

In general, this paper highlights the evolutionary position and significance of the lower fungi (Zygomycota and Chytridiomycota). Our results suggest that loss of the flagellum happened only once during early stages of fungal evolution; consequently, the majority of fungi, unlike plants and animals, are nonflagellated. The phylogeny we infer from gene sequences is the first one that is congruent with the widely accepted morphology-based classification of Fungi. We find that, contrary to what has been published elsewhere, the four morphologically defined phyla (Ascomycota, Basidiomycota, Zygomycota and Chytridiomycota) do not overlap with one another. Microsporidia are not included within kingdom Fungi; rather they are a sister-group to the Fungi. Our study demonstrates the applicability of protein sequences from large, slowly-evolving genes to the derivation of well-resolved and highly supported phylogenies across long evolutionary distances.

Tunable fly's-eye lens made of patterned polymer-dispersed liquid crystal

A fly's-eye lens was fabricated using polymer-dispersed liquid crystals and its optical properties were evaluated. The morphologies were examined under an optical microscope. The forming process has been simulated based on a patterned photo-polymerization technique in which the spatially modulated reaction rate has been coupled with the time-dependent Ginzburg-Landau (TDGL) equations with the free energies relating to isotropic mixing, nematic ordering, and network elasticity incorporated. The simulated results are in good agreement with the experimental results. The beam profile was tested using a CCD. The results showed that this fly's-eye lens could modulate a Gaussian beam into a mesa-like beam. Such device is potentially useful in beam shaping and many illumination systems that require uniform beam profile.

Role of Ichthyophthirius multifiliis in the Infection of Aeromonas hydrophila

Aeromonas hydrophila and Ichthyophthirius multifiliis are important fish pathogens. To clarify their relationship, two host models, goldfish with trauma and those infected with I. multifiliis, were used to study infection kinetics of A. hydrophila 4332 tagged with plasmid pGFPuv (Ah4332(GFP)). The results showed that in fish suffering from ichthyophthiriosis, the bacterial infection process was accelerated and more persistent than in the other groups. It is suggested that I. multifiliis plays an important role in the infection of A. hydrophila. Mechanical trauma caused by I. multifiliis might act as a portal of entry for A. hydrophila present in the water, thereby facilitating the invasion of bacteria. The ectoparasite might also serve as a vector and reservoir of pathogenic bacteria.

Toxicity and Cerebrospinal Fluid Levels of Carboplatin Chronically Infused into the Brainstem of a Primate

PURPOSE

Carboplatin was infused into the brainstem of cynomolgus monkeys to investigate neurotoxicity and systemic exposures following chronic local delivery.

METHODS

Infusions at 0.42 microl/h were intended to deliver 0.025 (n = 2), 0.075 (n = 3), 0.25 (n = 5), and 0.75 (n = 3) mg/kg by day 30. Laboratory tests, radiographic measurements, and clinical observations were used to monitor toxicity. Blood and cerebrospinal fluid (CSF) were sampled for platinum.

RESULTS

Lethargy and ataxia were observed after week 4 in the monkeys given 0.075 mg/kg, and week 2 in the monkeys given 0.25 mg/kg when the infused doses were approximately 250 and 400 microg, respectively. Rapidly progressive neurotoxicity with the 0.75 mg/kg dose required termination of the infusions at days 4-10. Hematology and chemistry values were unremarkable in all groups. Blood levels of platinum remained undetectable in 0.025 and 0.075 mg/kg dose groups. Levels in the 0.25 mg/kg group were 3.1 +/- 0.6 microg/l at 2 weeks and 5.2 +/- 0.8 microg/l at 1 month. The CSF platinum levels varied. Animals in the 0.25 mg/kg group had higher CSF levels at 2 weeks (avg. 65 microg/l, range 36-89) compared to their 1 month value (avg. 60 microg/l, range 7-170), despite the constant infusion.

CONCLUSION

Carboplatin can be chronically infused into monkey brainstems. Neurotoxicity is the predominant side effect and is dose-dependent. Pharmacokinetics of local and systemic delivery are different for carboplatin. Further studies are needed to monitor toxicity at higher flow rates and to investigate drug binding to abnormal central nervous system (CNS) tissues.

Body plan evolution of ascomycetes, as inferred from an RNA polymerase II phylogeny

The mode of evolution of the biologically diverse forms of ascomycetes is not well understood, largely because the descent relationships remain unresolved. By using sequences of the nuclear gene RPB2, we have inferred with considerable resolution the phylogenetic relationships between major groups within the phylum Ascomycota. These relationships allow us to deduce a historical pattern of body plan evolution. Within Taphrinomycotina, the most basal group, two simple body plans exist: uncovered asci with unicellular growth, or rudimentary ascoma with hyphal growth. Ancestral ascomycetes were filamentous; hyphal growth was lost independently in the yeast forms of Taphrinomycotina and Saccharomycotina. Pezizomycotina, the sister group to Saccharomycotina, retained mycelial growth while elaborating two basic ontogenetic pathways for ascoma formation and centrum development. The RPB2 phylogeny shows with significant statistical support that taxa in Pezizomycotina with ascohymenial ontogeny (ascoma generally forms after nuclear pairing) are ancestral and paraphyletic, whereas ascolocular fungi with fissitunicate asci are a clade derived from them. Ascolocular lichens are polyphyletic, whereas ascohymenial lichens comprise a monophyletic group that includes the Lecanorales. Our data are not consistent with a derived origin of Eurotiomycetes including Aspergillus and Trichophyton from within a lichen-forming ancestral group. For these reasons, the results of this study are considerably at variance with the conclusion that major fungal lineages are derived from lichensymbiotic ancestors. Interpretation of our results in the context of early work suggests that ascoma ontogeny and centrum characters are not in conflict with the molecular data.

Association of estrogen receptor alpha and vitamin D receptor gene polymorphisms with bone mineral density in Chinese males

Osteoporosis is a common health problem not only in females but also in males, however, studies of osteoporosis in males are relatively rare compared to those in females. This is especially true in genetics studies. We evaluated the effects of PvuII and XbaI polymorphisms in the estrogen receptor alpha (ER-alpha) gene and ApaI polymorphism in the vitamin D receptor (VDR) gene on BMD variation in a random sample of 352 unrelated males from 401 Chinese nuclear families. BMD was measured at the lumbar spine (L1-L4) and hip (femoral neck, trochanter, intertrochanteric region). Raw BMD values were adjusted by age, age(2), height, and weight as covariates. We found no significant results for the 3 individual markers on BMD variation, however, ER-alpha haplotype analyses yielded some interesting results. Carriers of haplotype pX had a 4.98% lower BMD at the trochanter (P = 0.02) and 3.55% lower BMD at the lumbar spine (P = 0.09) than non-carriers. PX subjects had a 3.42% higher BMD at the trochanter and 3.26% higher BMD at the lumbar spine than others (P = 0.07 and P = 0.10, respectively). Such results were highly comparable with the significant or nearly significant interactions between ER-PvuII and ER-XbaI on BMD values at the trochanter (P = 0.03) and spine (P = 0.11). No significant results were observed for the interactions between ER-PvuII and VDR-ApaI, between ER-XbaI and VDR-ApaI, and between any of ER-alpha haplotypes and VDR-ApaI locus. Our results suggest that the ER-alpha haplotypes, not individual markers, may be associated with BMD variation at some skeletal sites in our Chinese male samples.

Tests of linkage and association of the COL1A2 gene with bone phenotypes' variation in Chinese nuclear families

In the present study, we simultaneously test linkage and/or association of the collagen type I alpha 2 (COL1A2) gene with bone mineral density (BMD) and bone area. A total of 1280 subjects from 407 Chinese nuclear families (including both parents and their daughters) were genotyped for an intragenic marker MspI in the COL1A2 gene. BMD and bone area at the lumbar spine and hip were measured by dual-energy X-ray absorptiometry. Applying the QTDT (quantitative transmission disequilibrium test) program, we performed tests for population stratification, within-family association (via transmission disequilibrium test), total association, linkage, and linkage while modeling association. Significant or marginal within-family associations were found with BMD at the lumbar spine (P = 0.013), trochanter (P = 0.004), and total hip (P = 0.053) and with bone area at the intertrochanteric region (P = 0.024) and total hip (P = 0.048). The positive associations were confirmed in permutations except for bone area at total hip (P > 0.10). A small proportion (<1%) of the population variance of bone phenotypes can be explained by the MspI polymorphism; however, it may be underestimated given the significant population stratification detected in our sample. Due to the limited number of sib pairs in this sample, we did not find evidence of linkage. In summary, the MspI polymorphism is likely to be in linkage disequilibrium with a nearby functional mutation affecting BMD and bone area.

No evidence for linkage and/or association of human alpha2-HS glycoprotein gene with bone mineral density variation in Chinese nuclear families

Osteoporosis is an important health problem in the world. Alpha2-HS glycoprotein (AHSG) is involved in bone formation and metabolism and has been considered as an important candidate gene for osteoporosis. In this study, we simultaneously tested linkage and/or association of the AHSG gene with the variation of bone mineral density (BMD), an important risk factor for osteoporosis. A sample of 1,260 subjects from 401 Chinese nuclear families (including both parents and their daughters) were studied. The daughters' ages ranged from 20 to 45 years. All the subjects were genotyped by PCR-RFLP (polymerase chain reaction-restriction fragment length polymorphism) at polymorphic Sac I site inside the exon 7 of the AHSG gene. This polymorphism involves a nucleotide substitution of C to G at the middle nucleotide of the codon at amino acid position 238, resulting in the replacement of threonine (ACC) with serine (AGC). BMD was measured at the lumbar spine and hip region by dual-energy X-ray absorptiometry (DXA). Using the QTDT (quantitative trait transmission disequilibrium test), we found no significant results for association or linkage between the AHSG gene and BMD variation at the spine or hip. Our data provided no evidence to support the AHSG gene as a quantitative trait locus (QTL) for the BMD variation in a Chinese population.