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Biomedical subjects

T Li

Publications and source records attributed to T Li.

At least 37 records · Page 2Linked to original sources
PubMed2005

Human cystic echinococcosis in two Mongolian communities in Hobukesar (China) and Bulgan (Mongolia).

In order to investigate the prevalence of human cystic echinococcosis (CE) in traditional Mongolian communities in western Mongolia and Xinjiang (northwest China), studies were carried out between 1995 and 2000, on two ethnically identical populations in Hobukesar (China) and Bulgan (Mongolia). The prevalence of human hepatic CE in the two communities was significantly different. In Hobukesar, human CE prevalence by ultrasound was 2.7% (49/1844), while in Bulgan it was 0.2% (4/1609) (P<0.001). Dog surveys showed that coproantigen-positive rates or dog necropsy positives were similar in both communities (35.0% in Hobukesar and 35.7% in Bulgan). Comparing possible risk factors, there appeared to be some significant differences between the two communities, which might contribute to the observed difference in CE prevalence. These included: the proportion of herdsman or farmers recorded; the proportions of dog ownership and livestock ownership; and the proportion of families practising home slaughter. The presence of a Russian dog-dosing programme up to the mid-1980s may explain the lower prevalence of human CE in the Bulgan population; no similar programme operated in the China-administered Hobukesar community.

Animals↗
PubMed2005

siRNA targeting the leader sequence of SARS-CoV inhibits virus replication.

SARS-CoV (the SARS-Associated Coronavirus) was reported as a novel virus member in the coronavirus family, which was the cause of severe acute respiratory syndrome. Coronavirus replication occurs through a unique mechanism employing Leader sequence in the transcripts when initiating transcription from the genome. Therefore, we cloned the Leader sequence from SARS-CoV(BJ01), which is identical to that identified from SARS-CoV(HKU-39849), and constructed specific siRNA targeting the Leader sequence. Using EGFP and RFP reporter genes fused with the cloned SARS-CoV Leader sequence, we demonstrated that the siRNA targeting the Leader sequence decreased the mRNA abundance and protein expression levels of the reporter genes in 293T cells. By stably expressing the siRNA in Vero E6 cells, we provided data that the siRNA could effectively and specifically decrease the mRNA abundance of SARS-CoV genes as analyzed by RT-PCR and Northern blot. Our data indicated that the siRNA targeting the Leader sequence inhibited the replication of SARS-CoV in Vero E6 cells by silencing gene expression. We further demonstrated, via transient transfection experiments, that the siRNA targeting the Leader sequence had a much stronger inhibitory effect on SARS-CoV replication than the siRNAs targeting the Spike gene or the antisense oligodeoxynucleotides did. This report provides evidence that targeting Leader sequence using siRNA could be a powerful tool in inhibiting SARS-CoV replication.

5' Untranslated Regions↗
PubMed2005

Identifying potential risk haplotypes for schizophrenia at the DTNBP1 locus in Han Chinese and Scottish populations.

The dystrobrevin-binding protein 1 (DTNBP1) gene on chromosome 6p has emerged as a potential susceptibility gene for schizophrenia. Although a number of attempts to replicate the original association finding have been successful, they have not identified any obvious pathogenic variants or a single at risk haplotype common to all populations studied. In the present study we attempted further replication in an independent sample of 638 nuclear families from the Han Chinese population of Sichuan Province, SW China. We also examined 580 Scottish schizophrenic cases and 620 controls. We genotyped 10 single-nucleotide polymorphisms (SNPs) in DTNBP1 that were used in the original report of association, plus rs2619538 (SNP 'A') in the putative promoter region, which has also been associated with schizophrenia. In the Chinese trios we found that two SNPs (P1635 and P1765) were significantly overtransmitted, but with alleles opposite to those reported in the original studies. SNPs P1757 and P1765 formed a common haplotype, which also showed significant overtransmission. In the Scottish cases and controls, no individual markers were significantly associated with schizophrenia. A single haplotype, which included rs2619538 and P1583, and one rare haplotype, composed of P1320 and P1757, were significantly associated with schizophrenia, but no previously reported haplotypes were associated. Based on the data from the Chinese population, our results provide statistical support for DTNBP1 as a susceptibility gene for schizophrenia, albeit with haplotypes different from those of the original study. However, our lack of replication in the Scottish samples also indicates that caution is warranted when evaluating the robustness of the evidence for DTNBP1 as genetic risk factor for schizophrenia.

Alleles↗
PubMed2005

Autoantibody production from a thymoma and a follicular dendritic cell sarcoma associated with paraneoplastic pemphigus.

BACKGROUND: Paraneoplastic pemphigus (PNP) is an autoimmune mucocutaneous disease. We previously reported that B cells in a Castleman tumour associated with PNP produced autoantibodies. However, it is uncertain whether the production of autoantibodies from the associated tumour is a common mechanism in PNP. OBJECTIVES: To investigate autoantibody production in a thymoma and a follicular dendritic cell sarcoma that were excised from two patients with PNP. METHODS: Tumour cells were cultured, and their surface markers were identified. Indirect immunofluorescence, immunoblotting and enzyme-linked immunosorbent assay (ELISA) using culture media from the tumours were used to detect PNP autoantibodies. RESULTS: B cells with markers (CD22+, surface membrane IgG+ and surface membrane IgM+) of mature B lymphocytes constituted a proportion of cultured tumour cells in both tumours. Western blot showed that the medium from both the thymoma and the follicular dendritic cell sarcoma cells recognized 190-kDa periplakin and 210-kDa envoplakin bands of human epithelial proteins as well as recombinant linker regions of periplakin, envoplakin, desmoplakin and bullous pemphigoid antigen 1. ELISA was positive for antidesmoglein 3 antibody. CONCLUSIONS: The presence and localization in tumours of B-lymphocyte clones against proteins of the plakin family and desmoglein 3 in skin may not be confined to PNP with Castleman disease, but is possibly a common mechanism in PNP associated with various tumours.

Adult↗
PubMed2005

Association analysis of the RGS4 gene in Han Chinese and Scottish populations with schizophrenia.

We investigated the RGS4 as a susceptibility gene for schizophrenia in Chinese Han (184 trios and 138 sibling pairs, a total of 322 families) and Scottish (580 cases and 620 controls) populations using both a family trio and case-control design. Both the samples had statistical power greater than 70% to detect a heterozygote genotype relative risk of >1.2 for frequent RGS4-risk alleles. We genotyped four single nucleotide polymorphisms (SNPs) which have previously been associated with schizophrenia as either individually or part of haplotypes. Allele frequencies and linkage disequilibrium between the SNPs was similar in the two populations. In the Chinese sample, no individual SNPs or any of their haplotypes were associated with schizophrenia. In the Scottish population, one SNP (SNP7) was significantly over-represented in the cases compared with the controls (0.44 vs. 0.38; A allele; chi(2) 7.08, P = 0.011 after correction for correlation between markers by permutation testing). One two-marker haplotype, composed of alleles T and A of SNP4 and SNP7, respectively, showed individual significance after correction by permutation testing (chi(2) 6.8; P = 0.04). None of the full four-marker haplotypes showed association, including the G-G-G-G haplotype previously associated with schizophrenia in more than one sample and the A-T-A-A haplotype. Thus, our data do not directly replicate previous associations of RGS4, but association with SNP 7 in the Scottish population provides some support for a role in schizophrenia susceptibility. We cannot conclusively exclude RGS4, as associated haplotypes are likely to be surrogates for unknown causative alleles, whose relationship with overlying haplotypes may differ between the population groups. Differences in the association seen across the two populations could result from methodological factors such as diagnostic differences but most likely result from ethnic differences in haplotype structures within RGS4.

Case-Control Studies↗
PubMed2005

Radiation dose reduction in four-dimensional computed tomography.

Four-dimensional (4D) CT is useful in many clinical situations, where detailed abdominal and thoracic imaging is needed over the course of the respiratory cycle. However, it usually delivers a larger radiation dose than the standard three-dimensional (3D) CT, since multiple scans at each couch position are required in order to provide the temporal information. Our purpose in this work is to develop a method to perform 4D CT scans at relatively low current, hence reducing the radiation exposure of the patients. To deal with the increased statistical noise caused by the low current, we proposed a novel 4D penalized weighted least square (4D-PWLS) smoothing method, which can incorporate both spatial and phase information. The 4D images at different phases were registered to the same phase via a deformable model, thereby, a regularization term combining temporal and spatial neighbors can be designed for the 4D-PWLS objective function. The proposed method was tested with phantom experiments and a patient study, and superior noise suppression and resolution preservation were observed. A quantitative evaluation of the benefit of the proposed method to 4D radiotherapy and 4D PET/CT imaging are under investigation.

Biophysical Phenomena↗
PubMed2004

Joint role of non-HDL cholesterol and glycated haemoglobin in predicting future coronary heart disease events among women with type 2 diabetes.

AIMS/HYPOTHESIS: Non-HDL cholesterol (the sum of LDL, VLDL and IDL cholesterol) is considered to be particularly valuable in the management of dyslipidaemia in type 2 diabetes. However, it remains uncertain whether the association between non-HDL cholesterol and cardiovascular risk in type 2 diabetes depends on the status of hyperglycaemia. We aimed to determine whether non-HDL cholesterol predicts CHD events among diabetic women independently of currently established risk factors and the status of glycaemic control. METHODS: We prospectively followed 921 diabetic women in the Nurses' Health Study, who were free of cardiovascular disease at the time that blood was drawn in 1989/90. During 10 years of follow-up, we identified 122 incident CHD cases. RESULTS: After adjustment for age, BMI, smoking, alcohol consumption, and other lifestyle risk factors, the multivariate relative risks (RRs) of CHD for extreme quartiles were 1.97 (95% CI: 1.14-3.43) for non-HDL cholesterol, 1.78 (1.02-3.11) for apolipoprotein B-100, and 1.93 (1.15-3.22) for LDL cholesterol. However, the association between non-HDL cholesterol and CHD risk was only apparent among women with elevated fasting triglycerides (RR for extreme quartiles: 3.80; p=0.045). HbA(1)c was strongly associated with increased CHD risk (RR for increase by 1 unit: 1.24; 95% CI: 1.13-1.35), and both non-HDL cholesterol and HbA(1)c additively predicted CHD risk (RR for the combination of high non-HDL cholesterol and high HbA(1)c [tertiles]: 4.59). CONCLUSIONS/INTERPRETATION: Our study suggests that non-HDL cholesterol and HbA(1)c are potent predictors of CHD risk in diabetic women. Therapies to lower CHD risk in diabetic patients should emphasise both glycaemic control and lipid lowering.

Adult↗
PubMed2004

Computed tomography of odontogenic myxoma.

AIM: The aim of this study was to determine the computed tomography (CT) presentation of odontogenic myxoma (OM) in a Chinese population and to compare them with those observed on the accompanying conventional radiographs (CR). MATERIALS AND METHODS: The files of the Department of Oral and Maxillofacial Surgery of the University of Hong Kong between 1989 and 2000 were reviewed for myxoma cases. RESULTS: Ten cases of OM were found of which eight had been investigated by CT. The formatted hard copy was found in seven cases, four in the maxilla and three in the mandible. Most of the OMs had a round shape but one was fusiform. CT was more likely to display a cortex and its perforation. All OMs had perforated cortices on CT with soft tissue appearing outside the bony contour in two cases. Contrast enhancement was apparent in six cases. Both CR and CT displayed septae, but the latter method revealed that most septae were situated at the periphery, presenting as "sunray" type spicules in one case. Tooth displacement and root resorption were more reliably observed on CR. CONCLUSION: The likelihood of perforation and pattern of septa of OM is better displayed by CT. CR should also allow a better assessment of the degree of definition of the lesion's margins with adjacent normal bone. Therefore, both CT and CR should be used in an investigation of an OM.

Adolescent↗
PubMed2004

A clinically meaningful difference was generated for a performance measure of recovery from hip fracture.

BACKGROUND AND OBJECTIVE: The Lower Extremity Gain Scale (LEGS) is a performance measure of tasks that are often impaired in hip fracture patients. This study was designed to determine a clinically meaningful difference in LEGS. METHODS: The population was 139 female patients (age >65 years) admitted to Baltimore hospitals. Recovery levels were estimated by fitting trajectory curves for the cohort for the 12 months post fracture. The clinically meaningful difference was evaluated using an anchor-based approach, examining the relationship between the LEGS recovery level and age. A second, distribution-based method used an effect size of .20. RESULTS: According to our model, a difference of 5 years in age corresponded to a difference of 1.6-3.6 points in LEGS scores. The standard deviation for LEGS at 12 months was 8.0; thus, Cohen's effect size of 0.2 would equate to a difference of 1.6 points. CONCLUSION: This suggests that a clinically meaningful difference in the LEGS scores for a population in this age range would be 2-3 points.

Activities of Daily Living↗
PubMed2004

Commonalities and differences among vectorized beamformers in electromagnetic source imaging.

A number of beamformers have been introduced to localize neuronal activity using magnetoencephalography (MEG) and electroencephalography (EEG). However, currently available information about the major aspects of existing beamformers is incomplete. In the present study, detailed analyses are performed to study the commonalities and differences among vectorized versions of existing beamformers in both theory and practice. In addition, a novel beamformer based on higher-order covariance analysis is introduced. Theoretical formulas are provided on all major aspects of each beamformer; to examine their performance, computer simulations with different levels of correlation and signal-to-noise ratio are studied. Then, an empirical data set of human MEG median-nerve responses with a large number of neuronal generators is analyzed using the different beamformers. The results show substantial differences among existing MEG/EEG beamformers in their ways of describing the spatial map of neuronal activity. Differences in performance are observed among existing beamformers in terms of their spatial resolution, false-positive background activity, and robustness to highly correlated signals. Superior performance is obtained using our novel beamformer with higher-order covariance analysis in simulated data. Excellent agreement is also found between the results of our beamformer and the known neurophysiology of the median-nerve MEG response.

Brain↗
PubMed2004

Association between apolipoprotein CI HpaI polymorphism and sporadic Alzheimer's disease in Chinese.

OBJECTIVE: To investigate into the relationship of apolipoprotein CI (ApoCI) polymorphism with sporadic Alzheimer's disease (AD) in Chinese. SUBJECTS AND METHODS: A total of 257 AD patients and 242 age-matched elderly individuals were genotyped for the ApoCI HpaI and apolipoprotein E (ApoE) HhaI polymorphisms. RESULTS: The ApoCI A allele was associated with AD of moderate to severe dementia when patients were divided into two subgroups according to Clinical Dementia Rating scale, and the AA genotype was strongly associated with moderate to severe AD in ApoE epsilon4 allele carriers [odds ratio (OR) = 8.19, 95% confidential interval: 1.28-52.30, after adjusting for age and gender by logistic regression analysis], although in total no significant differences of allele or genotype frequency between patients and controls were found. CONCLUSION: The present study partially confirmed the previous findings, suggesting that the ApoCI A allele might contribute to the susceptibility to moderate to severe sporadic AD in Chinese.

Aged↗
PubMed2004

Identification of a novel neuregulin 1 at-risk haplotype in Han schizophrenia Chinese patients, but no association with the Icelandic/Scottish risk haplotype.

To determine if neuregulin 1 (NRG1) is associated with schizophrenia in Asian populations, we investigated a Han Chinese population using both a family trio design and a case-control design. A total of 25 microsatellite markers and single nucleotide polymorphisms (SNPs) were genotyped spanning the 1.1 Mb NRG1 gene including markers of a seven-marker haplotype at the 5' end of the gene found to be in excess in Icelandic and Scottish schizophrenia patients. The alleles of the individual markers forming the seven marker at-risk haplotype are not likely to be causative as they are not in excess in patients in the Chinese population studied here. However using unrelated patients, we find a novel haplotype (HAP(China 1)), immediately upstream of the Icelandic haplotype, in excess in patients (11.9% in patients vs 4.2% in controls; P=0.0000065, risk ratio (rr) 3.1), which was not significant when parental controls were used. Another haplotype (HAP(China 2)) overlapping the Icelandic risk haplotype was found in excess in the Chinese (8.5% of patients vs 4.0% of unrelated controls; P=0.003, rr 2.2) and was also significant using parental controls only (P=0.0047, rr 2.1). A four-marker haplotype at the 3' end of the NRG1 gene, HAP(China 3), was found at a frequency of 23.8% in patients and 13.7% in nontransmitted parental haplotypes (P=0.000042, rr=2.0) but was not significant in the case-control comparison. We conclude that different haplotypes within the boundaries of the NRG1 gene may be associated with schizophrenia in the Han Chinese.

Asian People↗
PubMed2003

Detection of human papillomavirus-16 in ovarian malignancy.

Human papillomavirus is the causal factor for cervical cancer. However, the role of HPV infection in ovarian cancer is unclear. This study aimed to determine the presence of human papillomavirus-16 (HPV-16) in ovarian cancer tissues. Archived human ovarian cancer tissues (N=54 cases, 50 are epithelial cancer, four are nonepithelial cancer) embedded in paraffin blocks were used. Controls are 30 nonmalignant ovarian tissue blocks. In situ hybridisation (ISH) and immunohistochemistry (IHC) were used to detect the presence of HPV-16 and p53 expression. In all, 52 or 36% of the epithelial ovarian tumours detected by ISH or IHC, respectively, were HPV-16 E6 positive. In contrast, only 6.7% of normal ovarian tissues were HPV-16 positive proved by ISH. Human papillomavirus-16 infection was significantly higher in cancer tissues compared to controls with an odds ratio of 16.7 (95% confidence interval [CI]=3.2-71.4, P<0.01). No significant correlation between HPV-16 infection and histological types of cancer was found (P>0.05). p53 gene expression was detected in 42% epithelial ovarian cancers. No correlation between p53 expression and HPV-16 infection was found. The results showed the presence of HPV-16 E6 in ovarian carcinoma, suggesting that HPV infection might play a role in ovarian carcinogenesis.

Adult↗
PubMed2003

Effects of gamma2S subunit incorporation on GABAA receptor macroscopic kinetics.

GABA(A) receptors, the major inhibitory neurotransmitter receptors in the mammalian central nervous system, are heteropentameric proteins. We are interested in understanding the contribution of the gamma subunit to the kinetic properties of GABA(A) receptors. Studies in Xenopus oocytes have suggested that co-expression of alpha1, beta2, and gamma 2S subunits results in the formation of both alpha beta and alpha betagamma receptors (Boileau et al. 2002a; Boileau et al., 1998). Here, we have used an excess of the gamma 2S subunit in transfections of HEK293 cells to bias expression toward alpha beta gamma-containing receptors. Using rapid application and whole cell patch clamp techniques, we found that incorporation of the gamma subunit eliminated the rapid phases of desensitization and accelerated deactivation, consistent with a proposed role of desensitization in slowing deactivation. In addition, alpha betagamma receptors had an increased GABA EC(50), reduced sensitivity to block by Zn(2+), and did not display outward rectification as compared to alpha beta receptors.

Animals↗
PubMed2003

Normal retinal development and retinofugal projections in mice lacking the retina-specific variant of actin-binding LIM domain protein.

The actin-binding LIM domain protein (abLIM) is the mammalian homologue of UNC-115, a protein mediating axon guidance in C. elegans. AbLIM is widely expressed with three isoforms differing from one another by the length of their amino termini. Experiments utilizing dominant-negative mutants in the chick retina suggested a role for abLIM in axon path finding in retinal ganglion cells (RGCs). To investigate which variant is involved in the regulation of mammalian RGC axon guidance, we analyzed their expression profile in mice. The longest variant, abLIM-L, is highly enriched in the ganglion cell layer. AbLIM-L is up-regulated postnatally which temporally overlaps with the period of RGC axon remodeling. In contrast, the abLIM-M and abLIM-S variants are widespread and remain relatively constant through development. By selective gene targeting, we ablated abLIM-L to explore its functional significance in vivo. AbLIM-L mutant mice exhibit no apparent morphological or functional defects in photoreceptors and inner retinal neurons. Retinofugal projections and synaptic maturation also appear normal. These data suggest that abLIM-M is likely the isoform performing the essential function related to axon guidance.

Animals↗