A statistical measure for the skewness of X chromosome inactivation for quantitative traits and its application to the MCTFR data.

BACKGROUND: X chromosome inactivation (XCI) is that one of two chromosomes in mammalian females is silenced during early development of embryos. There has been a statistical measure for the degree of the skewness of XCI for qualitative traits. However, no method is available for such task at quantitative trait loci. RESULTS: In this article, we extend the existing statistical measure for the skewness of XCI for qualitative traits, and the likelihood ratio, Fieller's and delta methods for constructing the corresponding confidence intervals, and make them accommodate quantitative traits. The proposed measure is a ratio of two linear regression coefficients when association exists. Noting that XCI may cause variance heterogeneity of the traits across different genotypes in females, we obtain the point estimate and confidence intervals of the measure by incorporating such information. The hypothesis testing of the proposed methods is also investigated. We conduct extensive simulation studies to assess the performance of the proposed methods. Simulation results demonstrate that the median of the point estimates of the measure is very close to the pre-specified true value. The likelihood ratio and Fieller's methods control the size well, and have the similar test power and accurate coverage probability, which perform better than the delta method. So far, we are not aware of any association study for the X-chromosomal loci in the Minnesota Center for Twin and Family Research data. So, we apply our proposed methods to these data for their practical use and find that only the rs792959 locus, which is simultaneously associated with the illicit drug composite score and behavioral disinhibition composite score, may undergo XCI skewing. However, this needs to be confirmed by molecular genetics. CONCLUSIONS: We recommend the Fieller's method in practical use because it is a non-iterative procedure and has the similar performance to the likelihood ratio method.

A polysaccharide purified from Radix Adenophorae promotes cell activation and pro-inflammatory cytokine production in murine RAW264.7 macrophages.

Radix Adenophorae, a traditional Chinese medicine, has been reported to have a variety of biological functions. In the present study, a polysaccharide component, Radix Adenophorae Polysaccharide (RAPS), was purified from Radix Adenophorae by decoloring with ADS-7 macroporous adsorption resin, DEAE-52 cellulose ion-exchange chromatography, and Sephacryl S-300HR gel chromatography, with the purity of 98.3% and a molecular weight of 1.8 × 10(4) Da. The cell viability assay and microscopic examination revealed that RAPS promoted the proliferation and activation of macrophages. At 400 µg·mL(-1), RAPS stimulated RAW264.7 cell proliferation by 1.91-fold compared with the control. Meanwhile, RAPS significantly increased the secretion of pro-inflammatory cytokines (TNF-α and IL-6) in a dose-dependent manner in the supernatant of RAW264.7 cell culture as determined by ELISA. At 400 µg·mL(-1), the production of TNF-iα was 20.8-fold higher than that of the control. Simultaneously, the production of nitric oxide (NO) and the expression of inducible nitric oxide synthase (iNOS) were increased in RAW264.7 cells incubated with RAPS, as measured by Griess assay and Western blot analysis. The NO production of cells treated with RAPS (400 µg·mL(-1)) reached 15.8 µmol·L(-1), which was 30.4-fold higher than that of the control (0.53 µmol·L(-1)). These data suggested that RAPS may enhance the immune function and protect against exogenous pathogens by activating macrophages.

A B3LYP and MP2(full) theoretical investigation into the strength of the C-NO(2) bond upon the formation of the intermolecular hydrogen-bonding interaction between HF and the nitro group of nitrotriazole or its methyl derivatives.

The changes of bond dissociation energy (BDE) in the C-NO(2) bond and nitro group charge upon the formation of the intermolecular hydrogen-bonding interaction between HF and the nitro group of 14 kinds of nitrotriazoles or methyl derivatives were investigated using the B3LYP and MP2(full) methods with the 6-311++G**, 6-311++G(2df,2p) and aug-cc-pVTZ basis sets. The strength of the C-NO(2) bond was enhanced and the charge of nitro group turned more negative in complex in comparison with those in isolated nitrotriazole molecule. The increment of the C-NO(2) bond dissociation energies correlated well with the intermolecular H-bonding interaction energies. Electron density shifts analyses showed that the electron density shifted toward the C-NO(2) bond upon complex formation, leading to the strengthened C-NO(2) bond and the possibly reduced explosive sensitivity.

A centrifuge simulated push-pull manoeuvre with subsequent reduced +Gz tolerance.

The push-pull effect (PPE) has been recognized as a deleterious contributor to fatal flight accidents. The purpose of the study was to establish a push-pull manoeuvre (PPM) simulation with a tri-axes centrifuge, studying the effect of this PPM on the +Gz tolerance, and to make this simulation suitable for pilot centrifuge training. The PPM was realized through pre-programmed acceleration profiles consisting of -1 Gz for 5 s followed by a +Gz plateau for 10 s. Relaxed +Gz tolerance recordings were obtained from 20 healthy male fighter aircraft pilots and 6 healthy male volunteers through exposure to pre-programmed profiles with and without previous -1 Gz exposure. A statistically significant decrease in +Gz tolerance was seen in all subjects after -1 Gz for 5 s exposure, 0.87 ± 0.13 G in the volunteer group and 0.95 ± 0.25 G in the pilot group. The ear opacity pulse as a +Gz tolerance endpoint criterion was sometimes found to be unreliable during the PPM experiments. The simulated PPM in this study elicited a PPE, which was obvious from the significant reduction in +Gz tolerance. The PPM profile appears useful to be included in centrifuge training.

Rapid speciation analysis of by short column capillary electrophoresis on-line coupled with inductively coupled plasma mass spectrometry.

A method for mercury high throughput rapid speciation analysis was developed by short column capillary electrophoresis (SC-CE) coupled with inductively coupled plasma mass spectrometry (ICP-MS). A MicroMist nebulizer was employed to increase the nebulization efficiency and a laboratory-made removable SC-CE-ICP-MS interface on the basis of cross design was applied to alleviate buffer contamination of ICP-MS. In less than 60 s, methylmercury (MeHg(i)) and inorganic mercury (Hg(ii)) were separated in a 16 × 75 µm i.d. short fused-silica capillary at 21 kV, while a mixture of 30 mmol L-1 boric acid + 5% (v/v) CH3OH (pH = 8.60) acted as running electrolyte. The precisions (RSD, n = 5) of migration time and peak area for MeHg(i) and Hg(ii) were in the range of 1.4-2.6% and 3.3-3.4%, respectively. The limits of detection (3σ) mercury species were 9.7 µg L-1 and 12.0 µg L-1, respectively. The recoveries for Hg(ii) and MeHg(i) were in the range of 96-107% and 99-105%.

Rapid speciation of iron by on-line coupling of short column capillary electrophoresis and inductively coupled plasma mass spectrometry with the collision cell technique.

A method for rapid speciation analysis of iron was developed by on-line coupling of short column capillary electrophoresis and inductively coupled plasma mass spectrometry. The collision cell technique was used to eliminate argon-based polyatomic interferences and a Micromist nebulizer was employed to increase the nebulization efficiency. Rapid speciation analysis of Fe(II) and Fe(III) was achieved within 1 min by short column capillary electrophoresis in a 14 cm x 50 microm id capillary at 28 kV voltage with a mixture of 15 mmol/L tris(hydroxymethyl)aminomethane + 1 mmol/L 1,10-phenanthroline + 1 mmol/L EDTA (pH 8.6) as running electrolyte. The precisions (RSD, n = 5) of migration time and peak area for Fe(II) and Fe(III) were in the range of 1.0 - 2.6 and 1.9 - 3.9%, respectively. The limits of detection (3sigma) of Fe(II) and Fe(III) were 10.0 and 8.3 microg/L, respectively.

Short-column CE coupled with inductively coupled plasma MS for high-throughput speciation analysis of chromium.

A method was developed for high-throughput speciation analysis of chromium by on-line coupling of short-column capillary electrophoresis (SC-CE) and inductively coupled plasma mass spectrometry (ICP-MS). Baseline separation of Cr(III) and Cr(VI) was achieved within 1 min by SC-CE in a 15 cm x 75 microm id fused-silica capillary at 6 kV using 15 mM HNO(3) as running electrolyte. The precisions (RSD, n = 5) of migration time and peak area for Cr(III) and Cr(VI) were in the range of 1.8-2.4% and 2.2-5.7%, respectively. The limits of detection (3sigma) of Cr(III) and Cr(VI) were 1.8 and 1.9 microg/L, respectively. The synthesized samples containing Cr(III) and Cr(VI) species were determined by the developed SC-CE-ICP-MS hyphenated technique, and the recoveries of Cr(III) and Cr(VI) in the synthesized samples were in the range of 103-110% and 90-108%, respectively.

[Speciation analysis of mercury by capillary electrophoresis on-line coupled with inductively coupled plasma mass spectrometry based on a micro mist nebulizer and a removable interface].

A method for mercury speciation analysis was developed by CE-ICP-MS with a Micro Mist nebulizer and a removable interface. Contamination of ICP-MS detector by the rising solution was avoided with the use of a removable interface during capillary rinsing. Baseline separation of methylmercury (MeHg) and inorganic mercury (Hg2+) was obtained by CE in a 45 cm x 75 microm i.d. fused-silica capillary at 22.5 kV, while a mixture of 30 mmol(-1) H3BO3 + 10% CH3OH (pH 8.7) acted as running electrolyte. The precisions (RSD, n=5) of migration time and peak area for the mercury species were in the ranges of 3.5%-3.8% and 2.3%-5.1%, respectively. The limits of detection (3sigma) of MeHg and Hg2+ were 47 and 48 microg x L(-1), respectively.

[The protection effect of a new combined anti-G measure].

AIM: To observe the protection effect of a new combined anti-G measure which was composed of KH-x anti-G suit, unassisted PBG (positive pressure breathing for G, PBG) and PHP maneuver. The problem of fatigue and pain when using this measure was also discussed. METHODS: Five fully qualified centrifuge subjects were exposed to 5 groups of +Gz exposure: (1) relaxed tolerance, (2) KH-x and KT-x, (3) PBG, (4) 6.5 G 45 s, (5) 9.0 G 15 s. The subjective feeling of fatigue and pain induced by +Gz exposure was evaluated by the questionnaire after runs. RESULTS: There was no incidents of G-induced lose of consciousness in this study. The protective effect of KH-x and KT-x was 2.3 G while it was 1.7 G for PBG. All the subjects have accomplished the 4th and 5th runs. The pain has developed on neck, waist, arm and hands. The problem of waist pain was very significant. CONCLUSION: The new combined anti-G measure could meet the requirement of +9.0 Gz protection for high performance plane. How to prevent the occurrence of neck injury and alleviate the pain induced by G when using this measure should be studied further.

[+Gz protection of the on board oxygen generating system (OBOGS) and anti-G equipment].

OBJECTIVE: To investigate the +Gz protection of the on board oxygen generating system (OBOGS) and anti-G equipment. METHOD: Physical and physiological tests of the OBOGS and anti-G equipment were accomplished using human centrifuge. +Gz tolerance of ten male subjects with or without the anti-G suit, pressure breathing for G (PBG) and OBOGS were determined. RESULT: The performance of the OBOGS and anti-G equipment fulfilled the requirements. The +Gz protections of the anti-G suit, PBG, and anti-G system were 2.08 G, 1.92 G, and 3.92 G, respectively. CONCLUSION: The +Gz protection of the OBOGS and anti-G equipment satisfy the performance requirements of high performance aircraft.

[Chiral separation of enantiomers of synthesized amlodipine and its intermediate by capillary electrophoresis].

A capillary electrophoretic method for the chiral separation of enantiomers of synthesized amlodipine and its intermediate was developed. Several cyclodextrins (CDs) were applied as the chiral selectors and it was found that the ionic modified carboxymethyl-beta-cyclodextrin (CM-beta-CD) could give satisfactory enantioselectivity. In addition, the effects of the pH value of the buffer system, the concentration of the CD and the voltage on the chiral separation were investigated. The optimized buffer for amlodipine and its intermediate enantiomers was a buffer containing 30 mmol/L phosphate and 50 mmol/L CM-beta-CD (pH 6.12). Under these conditions, the resolutions of enantiomers of amlodipine and its intermediate were 1.73 and 1.55, respectively.