Validation of the quality of life questionnaire of the European foundation for osteoporosis (QUALEFFO-31) in Chinese

QUALEFFO-31 is a recently developed disease-specific instrument derived from QUALEFFO-41 and intended to have improved efficacy and response rates. We aimed to validate QUALEFFO-31 in Chinese and examine the use of QUALEFFO-31 in clinical practice. This questionnaire was translated into Chinese and applied to 118 case-control pairs aged between 50 and 85 years with prevalent osteoporotic vertebral fractures to evaluate its validity, repeatability, and discriminatory ability. It was also used to evaluate the quality of life (QOL) of 69 case-control trios with prevalent clinical and morphometric fractures. The QOL of all subjects was concurrently assessed using SF-36 for comparison. QUALEFFO-31 had good internal consistency with adequate convergent and discriminatory validity. The median test-retest repeatability ranged from 0.65-0.85. In general, there were good correlations between QUALEFFO-31 and SF-36. ROC curve analysis revealed that QUALEFFO-31 had significant ability to discriminate between clinical fracture subjects versus morphometric fracture subjects and controls. QUALEFFO-31 also demonstrated higher discriminatory capacity for pain. Subjects with clinical vertebral fractures (CVFs) had a significant reduction in QOL compared with other subjects. The QUALEFFO-31 is a useful tool for assessing QOL in Chinese. It was well accepted and significantly predictive of subjects with CVFs. © 2010 Clinical Rheumatology.published_or_final_versionSpringer Open Choice, 21 Feb 201

A PFC voltage regulator with low input current distortion derived from a rectifierless topology

Author name used in this publication: Chi K. Tse2006-2007 > Academic research: refereed > Publication in refereed journalVersion of RecordPublishe

Synthesis of impedance using switching converters

Author name used in this publication: Chi K. TseAuthor name used in this publication: Franki N.K. PoonAuthor name used in this publication: M.H. PongRefereed conference paper2005-2006 > Academic research: refereed > Refereed conference paperVersion of RecordPublishe

General impedance synthesis using simple switching converters

A general impedance synthesizer using a minimum number of switching converters is studied in this paper. We begin with showing that any impedance can be synthesized by a circuit consisting of only two simple power converters, one storage element (e.g., capacitor), and one dissipative element (e.g., resistor) or power source. The implementation of such a circuit for synthesizing any desired impedance can be performed by (i) programming the input current given the input voltage such that the desired impedance function is achieved; (ii) controlling the amount of power dissipation (generation) in the dissipative element (source) so as to match the required active power of the impedance to be synthesized. Then, the instantaneous power will automatically be balanced by the storage element. Such impedance synthesizers find a lot of applications in power electronics. For instance, a resistance synthesizer can be used for power factor correction (PFC), a programmable capacitor or inductor synthesizer (comprising of small high-frequency converters) can be used for control applications.published_or_final_versio

Synthesis of input-rectifierless AC/DC converters

This paper discusses the basic construction procedure and topological possibilities of creating ac/dc converters out of simple dc/dc converters. It is shown that two separately controlled dc/dc converters are sufficient for producing a regulated dc output and shaping the input current, from an ac voltage source, without the need for input rectifiers. Some design constraints are discussed, emanating from the limitation of the conversion ratios that can be achieved by particular dc/dc converters. Selected topologies are verified experimentally. This kind of rectifierless converters find applications in airborne power supplies where zero-crossing distortions are significant because of the inevitable phase-lead effect of the input rectifier bridge.published_or_final_versio

A PFC topology with low input current distortion suitable for aircraft power supplies

Author name used in this publication: Chi K. TseAuthor name used in this publication: M. H. PongRefereed conference paper2003-2004 > Academic research: refereed > Refereed conference paperVersion of RecordPublishe

General impedance synthesis using simple switching converters

Author name used in this publication: Chi K. TseAuthor name used in this publication: Franki N. K. PoonRefereed conference paper2005-2006 > Academic research: refereed > Refereed conference paperVersion of RecordPublishe

Synthesis of input-rectifierless ac-dc converters

Author name used in this publication: J. C. P. LiuAuthor name used in this publication: C. K. TseAuthor name used in this publication: M. H. PongRefereed conference paper2000-2001 > Academic research: refereed > Refereed conference paperVersion of RecordPublishe

Estrogen receptor α CA dinucleotide repeat polymorphism is associated with rate of bone loss in perimenopausal women and bone mineral density and risk of osteoporotic fractures in postmenopausal women

The association between a newly identified CA repeat polymorphism of the estrogen receptor alpha gene (ESR1) with osteoporosis was investigated. Postmenopausal women with <18 CA repeats had low BMD, increased rate of bone loss and increased fracture risk. Introduction: Studies have shown that intronic dinucleotide repeat polymorphisms in some genes are associated with disease risk by modulating mRNA splicing efficiency. D6S440 is a newly identified intronic CA repeat polymorphism located downstream of the 5′-splicing site of exon 5 of ESR1. Methods: The associations of D6S440 with bone mineral density (BMD), rate of bone loss and fracture risk were evaluated in 452 pre-, 110 peri- and 622 postmenopausal southern Chinese women using regression models. Results: Post- but not premenopausal women with less CA repeats had lower spine and hip BMD. The number of CA repeats was linearly related to hip BMD in postmenopausal women (β=0.008; p=0.004). Postmenopausal women with CA repeats <18 had higher risks of having osteoporosis (BMD T-score<-2.5 at the spine: OR 2.46, 95% CI 1.30-4.65; at the hip: OR 3.79(1.64-8.74)) and low trauma fractures (OR 2.31(1.29-4.14)) than those with ≥18 repeats. Perimenopausal women with <18 CA repeats had significantly greater bone loss in 18 months at the hip than those with ≥18 repeats (-1.96% vs. -1.61%, p=0.029). Conclusions: ESR1 CA repeat polymorphism is associated with BMD variation, rate of bone loss and fracture risk, and this may be a useful genetic marker for fracture risk assessment. © International Osteoporosis Foundation and National Osteoporosis Foundation 2007.link_to_subscribed_fulltex

T-1213C polymorphism of estrogen receptor beta is associated with low bone mineral density and osteoporotic fractures

Osteoporosis is a complex disease with a strong genetic component, but the genes involved are poorly defined. To determine whether estrogen receptor beta (ESR2) gene is an osteoporosis risk gene, we examined its association with bone mineral density (BMD) and fracture risk. Using a gene-based approach, a set of 12 polymorphisms of ESR2 was studied in 752 case-control pairs of southern Chinese in ethnicity. Among all polymorphisms, the most significant relation with BMD and fracture risk was observed with T-1213C. Subjects with low BMD had a higher frequency of the variant C allele of T-1213C (cases 11.4%, control 8.4%, P = 0.02). The C allele was associated with 4% reduction in BMD at both the spine and hip in women, and 11% reduction in spine BMD and 9% reduction in hip BMD in men. Similar results were seen with SNP haplotype analysis. Subjects with the C allele of T-1213C were associated with higher risks of osteoporosis and BMD T scores ≤ -2.5 (odds ratios: 2.2 at spine and 3.5 at femoral neck for women; 3.5 at lumbar spine for men). Postmenopausal women carrying this C allele were associated with 2.22-fold increased risk of osteoporotic fractures (95% confidence interval 1.26-4.25) even after adjusting for BMD. In conclusion, ESR2 is involved in BMD determination in both sexes. The T-1213C polymorphism influences the risk of fracture in postmenopausal women independent of BMD. © 2006 Elsevier Inc. All rights reserved.link_to_subscribed_fulltex