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Biomedical subjects

X Xue

Publications and source records attributed to X Xue.

At least 19 recordsLinked to original sources
PubMed2006

Genetic diversity of Picea asperata populations based on RAPDs.

The genetic diversity of ten natural populations of Picea asperata Mast. were studied using RAPD markers. A total of 160 reproducible fragments were produced from the ten primers used. The mean number of fragments detected per individual was 114.7. Altogether 120 fragments were polymorphic among the ten populations, none of them were found to be population-specific. Nei's expected heterozygosity (H (e)) ranged from 0.233 to 0.269, and the average was 0.247. The analysis of molecular variance revealed that the coefficient of gene differentiation among populations, based on F (ST) and the unbiased estimate PhiST, equaled 0.224 and 0.290, respectively. Such high values indicate that there is significant differentiation among populations, which could result from several factors, including restricted gene flow between populations (Nm = 0.866). Founder events may be another factor attributing to the high level of genetic differentiation. In addition, it was discovered that the geographic distribution is not correlated with the genetic distances among the populations of P. asperata.

Genetic Markers↗
PubMed2006

Reactive oxygen species mediate crosstalk between NF-kappaB and JNK.

The activation of NF-kappaB inhibits apoptosis via a mechanism involving upregulation of various antiapoptotic genes, such as cellular FLICE-inhibitory protein (c-FLIP), Bcl-xL, A1/Bfl-1, and X chromosome-liked inhibitor of apoptosis (XIAP). In contrast, the activation of c-Jun N-terminal kinase (JNK) promotes apoptosis in a manner that is dependent on the cell type and the context of the stimulus. Recent studies have indicated that one of the antiapoptotic functions of NF-kappaB is to downregulate JNK activation. Further studies have also revealed that NF-kappaB inhibits JNK activation by suppressing accumulation of reactive oxygen species (ROS). In this review, we will focus on the signaling crosstalk between the NF-kappaB and JNK cascades via ROS.

Animals↗
PubMed2003

Genetic analysis, molecular tagging and mapping of the thermo-sensitive genic male-sterile gene (wtms1) in wheat.

A thermo-sensitive genic male-sterile (TGMS) wheat line ( Triticum aestivum L.) BNY-S was obtained from the spontaneous mutant of BNY-F. Its fertility was decided by the temperature during the differentiation stage of the spikelets. BNY-S was completely sterile when the temperature was lower than 10 degrees C during the differentiation stage of the spikelets, but fertile when the temperature was higher than 10 degrees C. Genetic analysis indicated that the sterility of BNY-S was controlled by a single recessive gene, which was named as wtms1. An F(2) population, consisting of 3,000 individuals from the cross between BNY-S and Lankao 52-24, was used for genetic analysis and statistical analysis of the TGMS and, out of them, 158 sterile and 93 fertile extremes were present for molecular tagging and mapping of the wtms1 gene. SSR (simple sequence repeat) and AFLP (amplified fragment length polymorphism) techniques combined with BSA (bulked segregant analysis) were used to screen markers linked to the target gene. As a result, wtms1 was preliminarily mapped on chromosome 2B according to SSR analysis. In AFLP analysis, 14 polymorphic AFLP loci were identified with a linkage relation to the wtms1 gene. Then linkage analysis using the F(2) population showed that three of them, E: AAG/M: CTA(163), E: AGG/M: CTC(220) and E: ACA/M: CTA(160), were linked to the wtms1 gene relatively close to a genetic distance of 6.9 cM, 6.9 cM and 13.9 cM, respectively. Finally, the wtms1 gene was mapped between the SSR marker Xgwm 374 and the AFLP marker E: AAG/M: CTA(163) with the distance of 4.8 cM and 6.9 cM, respectively. A partial linkage map was constructed according the SSR and AFLP data.

Genes, Plant↗
PubMed2002

Fabrication and characterization of hydroxyapatite reinforced with 20 vol % Ti particles for use as hard tissue replacement.

Hydroxyapatite(HA)-based composite reinforced with 20 vol % titanium (Ti) particles was fabricated by hot pressing based on the studies of the structural stability of HA phase in HA-Ti composite by means of FTIR spectrometry and X-ray diffractometry. The mechanical properties and biological behaviors of the composite were investigated by mechanical and in vivo studies. The existence of Ti metal phase can promote the dehydration and decomposition of HA ceramic phase into the more stable calcium phosphate phases, such as alpha-Ca(3)(PO(4))(2) (alpha-TCP) and Ca(4)O(PO(4))(2) at high temperatures. Comparing with pure HA ceramic manufactured under the same conditions, HA-20 vol % Ti composite with higher fracture toughness (0.987 MPa m(1/2)), bending strength (78.59 MPa), work of fracture (12.8J/m(2)), porosity (9.8%) and lower elastic modulus (75.91 GPa) is more suitable for use as hard tissue replacement. Crack deflection is the chief toughening mechanism in the composite. Histological evaluation by light microscope shows HA-20 vol % Ti composite implant could be partially integrated with newborn bone tissues after 3 weeks and fully osteointegrated at 12 weeks in vivo. The excellent biological properties of HA-20 vol % Ti composite may be contributed to the coexistence of high porosity and the decomposition products of HA phase in the composite.

Journal Article↗
PubMed2001

Analysis of childhood brain tumour data in New York City using frailty models.

This paper uses frailty models to analyse overall survival and progression-free survival times for children with a brain tumour. We are interested in how surgery resection affects survival times. We are also interested in how strong a child's progression-free survival correlates with his/her overall survival and if the association differs with age. Traditionally the frailty is modelled parametrically and a maximum likelihood approach is used to estimate the parameters of interest. However, the result is sensitive to the misspecification of the frailty distribution and the currently developed algorithms for the maximum likelihood approach do not allow the association parameter to depend on covariates. Xue formulates a Poisson regression model and applies an estimating equation approach to obtain a consistent estimate of the covariate effect on survival. This paper extends that approach to obtain consistent and efficient estimates of the association parameter as well as the covariate effect and to allow the association parameter to depend on the covariates. The approach does not require the specification of the frailty distribution. The performance of the method is evaluated through simulation studies. We apply this method to a childhood brain tumour data set in New York City.

Age Factors↗
PubMed2001

Testing for gene-gene interaction controlling total IgE in families from Barbados: evidence of sensitivity regarding linkage heterogeneity among families.

Genetic heterogeneity has been proposed as a hallmark feature of allergic disease. To test the hypothesis that total IgE levels are jointly influenced by a locus on chromosome 12q21.1-q21.31 and a locus on 17q11.2-q21.2, we conducted multipoint allele-sharing analyses using nonparametric linkage (NPL) methods on Afro-Caribbean families from Barbados to test for evidence of gene-gene interactions. Significant correlations were observed between NPL scores at D12S1052 and both D17S1293 and D17S1299 for a dichotomized phenotype of total IgE. An analysis of family-specific NPL scores revealed that evidence for interaction was being driven largely by one multiplex pedigree (NPL = 12.01, 12.23, and 12.16 at D12S1052, D17S1293, and D17S1299, respectively). Using the programs SIMWALK (v2.0) and GOLD, a different set of haplotypes in this influential family was observed around D12S1052 and the 17q loci compared to the other Barbados pedigrees. Our findings are a classic example of founder effect, provide evidence for sensitivity of this type of linkage analysis to unusual pedigrees, and highlight an element of genetic heterogeneity that has been given little attention in the study of complex traits.

Asthma↗
PubMed2001

Epithelial ovarian carcinoma and European birthplace of grandparents.

OBJECTIVE: The aim of this study was to determine whether the risk of ovarian carcinoma was related to latitude or to genetically based patterns of European geographic origin. PATIENTS AND METHODS: We studied the countries of origin of European-born grandparents of 168 newly diagnosed patients in two hospitals in New York City, compared with 159 controls from similar neighborhoods. We measured the risk of this cancer associated with having one or more white, non-Jewish grandparents born in North Europe versus none or in South Europe versus none. We also classified geographic origins in other ways to reflect the two main trends in genetic variations between Europeans mapped by Cavalli-Sforza et al. (The History and Geography of Human Genes, Princeton University Press, Princeton, 1994). Unconditional logistic regression was used to control for age, parity, years of use of oral contraception, age at menarche, education, Catholic religion, and area of residence and for numbers of Jewish grandparents, siblings, and first-degree relatives with breast or ovarian cancer. RESULTS: Approximately half of the subjects had least one white, non-Jewish grandparent born in Europe. There was no significant effect of ancestral latitude: among women born in the United States the odds ratio (OR) and 95% confidence limits associated with North European ancestry were 0.87 (0.47--1.63) compared with a reference group of women with no such ancestry. The corresponding OR for South Europe was 0.73 (0.39--1.74). Using the genetically based classifications of countries of origin, however, we found significant differences between cases and controls; ancestries from North West Europe and those from countries concentrically near Spain showed lower risks of ovarian carcinoma. CONCLUSIONS: The results support the hypothesis that the previously observed effects of latitude must act through environmental effects or through gene-environment interactions. Other variations in risk related to geographic origins are consistent with known patterns of genetic differences, but require confirmation in larger, population-based studies.

Adult↗
PubMed2001

Assessing excess lifetime risk for disease after radiation exposure.

In this paper, we define the excess lifetime risk for a disease due to radiation exposure, and we evaluate the excess lifetime risk for an exposed group with the same age and with a mixture of ages. We propose two methods to estimate the excess lifetime risk: the standard maximum likelihood approach and a Monte-Carlo approach. Both approaches allow us to construct confidence intervals for the excess lifetime risk and perform hypothesis testing to compare two excess risks. The maximum likelihood approach is straightforward and computationally simple; however, it may not provide good approximations when the normality assumption is violated. The Monte-Carlo approach is always reliable, but often involves heavier computations and additional programming. These two approaches are illustrated and discussed based on a pooled analysis of five cohorts exposed to external radiation and followed up for subsequent thyroid cancer incidence.

Age Distribution↗
PubMed2001

Dental caries experience, tooth loss, and factors associated with unmet needs of Haitian immigrants in New York City.

OBJECTIVE: The aim of this study was to characterize the dental caries experience, tooth loss, and unmet need of a group of Haitian immigrant residents of New York City. METHODS: A purposive sample of 523 adults was obtained through community outreach activities during 1997-98. Clinical examinations were performed by calibrated examiners, according to NIDCR criteria. A comprehensive survey also was administered to all the participants. RESULTS: For the whole group, the mean number of missing teeth was 2.64 (SD = 4.12), the mean DMFT = 6.05 (SD = 5.26), the mean DMFS = 18.80 (SD = 21.04), and the mean DFS = 5.58 (SD = 6.17). Seventeen percent of the subjects had all their teeth sound, 59 percent had at least one tooth missing, 60 percent had at least one decayed tooth, and only 38 percent had restorations. Multivariate analyses showed that age, sex, education, dental insurance, frequency of dental visits, and dental floss use were predictors of unmet need. CONCLUSIONS: Although results showed a relatively low caries experience among this group of Haitian immigrants, the unmet need was very high. Furthermore, the tooth loss experience was relatively high for all age groups, further denoting a lack of access to preventive and restorative services.

Adolescent↗
PubMed2001

Effect of different bowel preparations on residual fluid at CT colonography.

The effect of different bowel preparations on residual fluid during computed tomographic (CT) colonography was evaluated. Forty-two patients received either a polyethylene glycol electrolyte solution preparation or a phospho-soda preparation the day prior to CT colonography. The amount of residual fluid was calculated for each patient. On average, a phospho-soda preparation provided significantly less residual fluid than a polyethylene glycol electrolyte solution preparation.

Aged↗
PubMed2000

An ab initio calculation of 17O and 29Si NMR parameters for SiO2 polymorphs.

Ab initio molecular orbital calculations (Hartree-Fock, HF and density functional theories, DFTs) have been carried out for SiO2 polymorphs coesite, low cristobalite, and alpha-quartz, in order to investigate the reliability of this method for predicting 29Si and 17O nuclear magnetic resonance (NMR) properties of silicates. Oxygen- and silicon-centered clusters consisting of one (1T) to three tetrahedral (3T) shells (one to four atomic shells), taken from real crystal structure, have been investigated. It is found that for reasonable predication of both the 29Si and 17O chemical shifts (deltaSi and delta(i)O), the minimum cluster is one that gives the correct second neighbors to the nucleus of interest. Both the delta(i)Si and delta(i)O have reached convergence with respect to cluster size at the OH-terminated two tetrahedral (2T) shell (three atomic shells around Si and four atomic shells around O) model. At convergence, the calculated delta(i)Si values agree well (within +/- 1 ppm) with experimental data. The calculated 17O electric field gradient (EFG)-related parameters also agree with experimental data within experimental uncertainties. The calculation also reproduces small differences in delta(i)O for O sites with similar tetrahedral connectivities, but shows deviations up to about 10 ppm in relative difference for O sites with different tetrahedral connectivities. The poor performance for the latter is mainly due to the approximations of the HF method. Our study thus suggests that the ab initio calculation method is a reliable mean for predicting 29Si and 17O NMR parameters for silicates. Such an approach should find application not only to well-ordered crystalline phases, but also to disordered materials, by combining with other techniques, such as the molecular dynamics simulation method.

Crystallization↗
PubMed2000

Assessment of autonomic function in patients with acute myocardial infarction or diabetes mellitus by heart rate variability, ventricular late potential and QT dispersion.

To compare the efficacy and sensitivity of heart rate variability (HRV), QT dispersion (QTd) and ventricular late potential (VLP) examination in judging autonomic function. Thirty three patients with acute myocardial infarction (AMI) and 33 patients with diabetes mellitus (DM), all of whom were diagnosed with autonomic neuropathy determined by a standard test of cardiovascular autonomic function, were examined by HRV (timing domain methods), QTd and VLP. Thirty three normal individuals served as controls. The mean SD of the normal R-R interval (SDNN) in both the AMI and DM groups was significantly less than that in the control group (p< 0.01); and of course, the QTd of these groups was significantly greater than that of the controls (p< 0.01). The VLP positive rate of the AMI and DM groups were much higher than that of the control group (p< 0.001). SDNN was shown to be significantly negatively correlated to QTd (r= -0.45); and significantly negatively correlated to VLP (r= -0.47); QTd was shown to be positively, though not significantly, correlated to VLP (r=0.48). QTd could be looked as sieving index; HRV could be looked as routine examination of cardiovascular autonomic function, especially SDNN; the combination of HRV and VLP could improve the accuracy of diagnosis.

Adult↗
PubMed2000

Intensity-based modal decomposition of optical beams in terms of Hermite-Gaussian functions

We show that when an arbitrary optical beam is decomposed into a superposition of Hermite-Gaussian functions, it is sufficient to record a number of intensity profiles sampled at various transverse planes to uniquely determine the relative modal weights. This result follows from the parity relation and the nature of the Gouy phase, in addition to the orthogonality of the Fourier-transformed intensity profiles associated with the Hermite-Gaussian modes.

Journal Article↗
PubMed2000

[Numerical taxonomy of medicinal plants from Areae in Zhejiang Province].

Numerical taxonomic studies were done on 13 species from 3 genera of tribe Areae in Zhejiang, used as 13 operational taxonomic units (OTUS). 40 morphological characters were used for analysis. Euclid distance coefficients used to show quantitative index of similarity among OTUS were computed by standardized data. The dendrograms from 8 systematic cluster methods including single linkage method, complete linkage method, median method (beta = 0 WPGMA) and (beta = -0.25 WPGMA), centroid method, group average method, variable group average method (beta = -0.25) and variable method (beta = 0.25) were constructed respectively. WPGMA was slected as the optimal one by computing the comparative coefficients of every cluster result and the boundary of taxa in its dendrogram determined by a method to treated IBM computer with the program by BASIC language. The Results showed that 13 OTUs were classified as 3 clusters by broken line L2, namely, cluster I: Typhonium; cluster II: Arisaema; cluster III: Pinellia, and cluster II further as 4 groups by L1, which belong to Section Pistillata, Arisaema, Sinarisaema and Tortuosa respectively. Being consistent with those from classical taxonomy, the results in this study may be helpful to the classification and identification of the medicinal plants from tribe Areae in Zhejiang Privince.

Araceae↗
PubMed1999

Assessing heterogeneity and correlation of paired failure times with the bivariate frailty model.

We consider bivariate survival times for heterogeneous populations, where heterogeneity induces deviations in an individual's risk of an event as well as associations between survival times. The heterogeneity is characterized by a bivariate frailty model. We measure the heterogeneity effects through deviations associated with hazard functions and an association function defined through the conditional hazard functions: the cross-ratio function proposed by Oakes. We show how the deviation and association measures are determined by the frailty distribution. A Gibbs sampling method is developed for Bayesian inferences on regression coefficients, frailty parameters and the heterogeneity measures. The method is applied to a mental health care data set.

Algorithms↗
PubMed1999

[Early use of Chinese drug rhodiola compound for patients with post-trauma and inflammation in prevention of ALI/ARDS].

OBJECTIVE: To evaluate the effects of the Chinese drug rhodiola on the preventive treatment of acute lung injury (ALI) caused by post-traumatic/inflammatory and thoracic-cardiovascular operations. METHODS: 104 patients who coincide with their diagnosis and standard scale were divided randomly in to single number groups A(1), B(1), C(1) and D(1) (early preventive treatment group EG) and double number groups A(2), B(2), C(2) and D(2) (control group CG). The treatment of primary disease both in EG and CG was similar, but in EG four grams of rhodiola compound (RCO) were used every day for a period of 3-15 days since admission and 5-7 days after operation. The indicators related to ALI in each groups were measured. RESULTS: PaO(2), AaDO(2) and hemorheology were significant in EG than in CG (P < 0.05) or (P < 0.01). The complication rate of ARDS was decreased about of 50.0% in EG than in CG. CONCLUSIONS: Early use of RCO may protect against major risk factors of ALI/ARDS caused by massive trauma/infection and thoracic-cardio-operations.

Adolescent↗