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Biomedical subjects

S Hui

Publications and source records attributed to S Hui.

At least 19 recordsLinked to original sources
PubMed2006

Saccades in presymptomatic and early stages of Huntington disease.

OBJECTIVE: To evaluate quantitative measures of eye movements as possible biomarkers in prediagnostic and early stages of Huntington disease (HD). METHODS: The study sample (n = 215) included individuals both at risk and recently diagnosed with HD. All participants completed a uniform clinical evaluation which included administration of the Unified Huntington's Disease Rating Scale (UHDRS) by a movement disorder neurologist and molecular testing to determine HD gene status. A high resolution, video-based eye tracking system was employed to quantify measures of eye movement (error rates, latencies, SD of latencies, velocities, and accuracies) during a computerized battery of saccadic and steady fixation tasks. RESULTS: Prediagnostic HD gene carriers and individuals with early HD demonstrated three types of significant abnormalities while performing memory guided and anti-saccade tasks: increased error rate, increased saccade latency, and increased variability of saccade latency. The eye movement abnormalities increased with advancing motor signs of HD. CONCLUSIONS: Abnormalities in eye movement measures are a sensitive biomarker in the prediagnostic and early stages of Huntington disease (HD). These measures may be more sensitive to prediagnostic changes in HD than the currently employed neurologic motor assessment.

Eye Movements↗
PubMed2005

Bone remodeling at the iliac crest can predict the changes in remodeling dynamics, microdamage accumulation, and mechanical properties in the lumbar vertebrae of dogs.

We previously demonstrated that suppression of bone remodeling allows microdamage to accumulate, thereby leading to reduced bone toughness in dog bone. In this study we evaluated the relationships between bone remodeling at the iliac crest and skeletal activation frequency, microdamage accumulation, or biomechanical properties of lumbar vertebrae using the same dogs to determine whether bone remodeling at the iliac crest can predict damage accumulation and mechanical parameters of the lumbar spine following treatment with antiresorptive agents. Thirty-six female beagles, 1 to 2 years old, were divided into three groups. The control group was treated daily for 12 months with saline vehicle. The remaining two groups were treated daily with oral risedronate at a dose of 0.5 mg/kg/day, or alendronate at 1.0 mg/kg/day orally. The doses of these bisphosphonates were 5 to 6 times the clinical doses approved for treatment of osteoporosis in humans. After sacrifice, the right ilium and L2 vertebra were assigned to histomorphometry. The left ilium and L3 vertebra were used for microdamage analysis. The L4 vertebra was mechanically tested to failure in compression, and bone toughness calculated from the stress-strain curve. There was a strong positive relationship for activation frequency (Ac.f) between ilium and lumbar vertebrae (r2 = 0.82; P < 0.0001). Iliac crest Ac.f underestimates Ac.f in L2, but L2 Ac.f reaches a minimum threshold and does not decline further when iliac crest Ac.f is below 0.10/yr. Microdamage (Cr.S.Dn) accumulation at the ilium was significantly associated with increased microdamage accumulation in the L3 lumbar vertebra (r2 = 0.43, P < 0.0001). The data also show that bisphosphonate treatment increased Cr.S.Dn at a faster rate in L3 than in the iliac crest. Although bisphosphonate treatment decreased bone toughness in L4, this decrease demonstrated no relationship to decreased Ac.f in the ilium. These results clearly indicate that bone remodeling data obtained from iliac crest biopsy could be used to estimate the activation frequency and microdamage burden in the vertebral column.

Administration, Oral↗
PubMed2004

Cholesterol and APOE genotype interact to influence Alzheimer disease progression.

In this retrospective analysis of 443 Alzheimer disease (AD) patients from a 30-week tacrine trial, change in Alzheimer's Disease Assessment Scale score from baseline to final value was significantly associated with a total serum cholesterol/APOE genotype interaction. Disease progression in the no-APOE epsilon4 allele/high-cholesterol subgroup was greater than in the normal-cholesterol subgroups with or without epsilon4. Cholesterol levels and APOE genotype may interact to affect AD progression. The results are consistent with preclinical data on cholesterol's effects in AD.

Aged↗
PubMed2003

Sleeping energy expenditure in paediatric patients with obstructive sleep apnoea syndrome.

OBJECTIVE: To investigate sleeping energy expenditure in paediatric patients with obstructive sleep apnoea syndrome. DESIGN: Retrospective study. Setting. University teaching hospital, Hong Kong. PATIENTS AND METHODS: A retrospective analysis comparing sleeping energy expenditure in patients with confirmed obstructive sleep apnoea syndrome and control subjects matched for age, sex, and ideal weight for body height. Subjects were recruited from the Paediatric Chest Clinic and all had undergone overnight polysomnography and sleeping energy expenditure measurement by open-circuit indirect calorimetry using a metabolic cart and canopy system. The measurements were taken during slow-wave sleep. RESULTS: Twenty-four cases with obstructive sleep apnoea syndrome (apnoea hypopnoea index >5) and 23 control subjects were studied. Mean age and ideal weight for body height were 9.4 (standard deviation, 3.9) years and 152.5% (27.2%), respectively. Mean sleeping energy expenditure corrected for body weight for the cases and the control group were 44.83 (standard deviation, 10.49) Kcal/day and 40.71 (10.60) Kcal/day, respectively. Sleeping energy expenditure was not found to be associated with the severity of obstructive sleep apnoea syndrome (r=0.34, P=0.27). CONCLUSION: A trend towards greater sleeping energy expenditure was found in patients with obstructive sleep apnoea syndrome. Further studies on the metabolic aspects of this condition are required.

Calorimetry, Indirect↗
PubMed2002

Use of tonsil size in the evaluation of obstructive sleep apnoea.

AIMS: (1) To determine the extent to which tonsil size contributes to the severity of obstructive sleep apnoea (OSA) in children; and (2) to assess the use of tonsillar-pharyngeal (TP) ratio in differentiating patients with different severity of OSA. METHODS: Lateral neck radiograph was performed on 35 children referred consecutively to a university paediatric chest clinic for suspected OSA secondary to tonsillar hypertrophy. The tonsil size was determined by measuring the TP ratio on the radiographs. The severity of OSA was assessed by overnight polysomnography. RESULTS: A total of 24 boys and 11 girls (median age 6.2 years) were studied. All presented with symptoms of OSA, and tonsillar hypertrophy was detected on clinical examination. The median apnoea-hypopnoea index (AHI) was 16.93 (interquartile range: 8.41 to 28.29). The median TP ratio was 0.76 (interquartile range: 0.65 to 0.80). AHI was positively correlated with the TP ratio. The clinical tonsil size did not correlate with the AHI or the TP ratio. Using a TP ratio of 0.479, the sensitivity and specificity in predicting cases with moderate/severe OSA (AHI >10) were 95.8% and 81.8% respectively, while the positive and negative predictive values were 92.0% and 90.0% respectively. CONCLUSIONS: Results show that in a population of children with OSA, tonsillar hypertrophy as assessed by lateral neck radiograph correlates positively with the severity of obstructive sleep apnoea. The TP ratio has high sensitivity and specificity in predicting those with moderate/severe disease and this feature may be used as a clinical screening method in prioritising patients with OSA for further assessment.

Child↗
PubMed2001

Standardization of bone mineral density at femoral neck, trochanter and Ward's triangle.

The International Committee for Standards in Bone Measurement (ICSBM) has published standardization formulas for total hip bone mineral density (BMD). In many applications, however, BMD of hip subregions, such as femoral neck (FN), trochanter (TR), and Ward's triangle (WT), are commonly measured. This paper addresses whether the standardization formulas for total hip BMD can be adequately used for hip subregions. We used data from 100 healthy women, from 20 to 80 years old, who had hip BMD measured in both the total hip and hip subregions by a Hologic QDR 2000, a Lunar DPX, and a Norland XR26 Mark II. The same women were used by ICSBM for the standardization of total hip BMD. In addition, we used data of 3139 patients from a clinical trial to validate our results. We derived standardization formulas for FN, TR, and WT using the same statistical method as that used for total hip BMD. We applied both total hip calibration formulas and subregion-specific formulas to the data and compared the corresponding effect. We found that the total hip calibration formulas can partially reduce BMD differences between the Hologic and Lunar as well as the Lunar and Norland scanners in hip subregions, but increase differences between the Hologic and Norland scanners. The subregion calibration formulas are most appropriate for calibrating subregion BMD values and their absolute changes, and should be adopted. Standardization is unnecessary for BMD percentage changes in our clinical trial data.

Absorptiometry, Photon↗
PubMed2001

Accurate case finding using linked electronic clinical and administrative data at a children's hospital.

To link hospital administrative data and an electronic medical record at a children's hospital in order to identify children with cancer admitted for fever and neutropenia. Hospital administrative data concerning 13,374 inpatient and outpatient encounters were validated against and linked to clinical data stored in an electronic medical record. Queries of the linked databases identified children with fever and neutropenia. Sensitivity and specificity of the experimental case-finding strategy were determined and compared to a control case-finding strategy utilizing administrative data alone. Linking of the clinical record to the administrative record was achieved in 233 (99%) of the 235 records. Of 1680 data elements reviewed from the administrative data that were also potentially available in the clinical data system, 1679 (99.9%) were verified in the electronic medical record. The experimental strategy for case finding had a sensitivity of 73.1% (95% CI: 58.1, 88.3), specificity 99.6% (95% CI: 99.1, 100). If only administrative data such as diagnosis-related group and hospital service were used for case finding, both the sensitivity (P < 0.01) and specificity (P < 0.01) were significantly lower. Linking a children's hospital administrative data system with clinical data is feasible and can be utilized for specific case finding for a common and costly condition in children.

Child↗
PubMed2001

[The effects of iron compounds on SO2 and NO emissions in coal combustion process].

The effects of ferric/ferrous chlorides and ferric oxide on emissions in Tongchuan coal combustion process were experimentally investigated using thermogravimetric analyzer. The results show that all iron compounds used in the experiments, namely FeCl3, FeCl2 and Fe2O3 can change the emissions of SO2 and NO, but with different mechanisms and different magnitudes. FeCl3 plays the roles of both a catalyst and an absorbent in the conversions from coal-S to SO2 and from coal-N to NO. Due to the catalysis the activation energy required for the formation of SO2 and NO is reduced, the rates of the reactions leading to SO2 and NO increased. The catalysis is concerned with the forms of coal sulfur. Due to the absorption FeCl3 reacts with SO2 to produce FeSO4 [symbol: see text] Fe2(SO4)3. In addition FeCl3 can decrease the emissions of CO, i.e., the combustion characteristics can be changed. The effects of FeCl2 on the emissions of SO2, NO and CO are similar to those of FeCl3, but weaker. Fe2O3 can also decrease the SO2 and NO emissions to some extent, but has negligible influence on CO emission.

Catalysis↗
PubMed2001

Obstructive sleep apnoea in children with adenotonsillar hypertrophy: prospective study.

OBJECTIVE: To determine clinical and baseline polysomnographic data on obstructive sleep apnoea secondary to adenotonsillar hypertrophy in Hong Kong Chinese children. DESIGN: Prospective study. SETTING: University teaching hospital, Hong Kong. PARTICIPANTS: Fifty children (35 boys and 15 girls) suspected to have obstructive sleep apnoea were recruited between January 1999 and December 1999. MAIN OUTCOME MEASURES: Symptoms questionnaire, electrocardiogram, chest radiograph, and full-night polysomnography. RESULTS: All patients had symptoms suggestive of obstructive sleep apnoea. None were found to have clinical evidence of cor pulmonale. Forty-five (90%) of 50 children had obstructive sleep apnoea with a respiratory disturbance index of greater than five. Central and mixed apnoeas were rare. Tonsil size did not correlate with the severity of obstructive sleep apnoea. CONCLUSION: Symptoms and signs suggestive of obstructive sleep apnoea can lead to a high detection rate and confirmation of obstructive sleep apnoea by polysomnography.

Adenoids↗
PubMed2000

Effect of free fatty acids on the permeability of 1,2-dimyristoyl-sn-glycero-3-phosphocholine bilayer at the main phase transition.

We measured the influence of saturated and unsaturated free fatty acids on the permeability and partition of ions into 1, 2-dimyristoyl-sn-glycero-3-phosphocholine (DMPC) bilayers. The bilayer permeability was measured using the depletion of N-(7-nitrobenz-2-oxa-1,3-diazol-4-yl)-1, 2-dihexadecanoyl-sn-glycero-3-phosphatidylethanolamine (N-NBD-PE) fluorescence as a result of its reduction by dithionite. We observed a distinct increase of dithionite permeability at the main gel-fluid phase transition of DMPC. When vesicles were formed from a mixture of DMPC and oleic acid, the membrane permeability at the phase transition was reduced drastically. Stearic acid and methyl ester of oleic acid have little effect. Similar results in the quenching of pyrene-PC in DMPC vesicles by iodide were obtained. Again, the increase of iodide partition into the lipid phase at the main phase transition of DMPC was abolished by the addition of unsaturated free fatty acids. Free fatty acids, in concentrations up to 5 mol%, do not abolish DMPC phase transition when measured by differential scanning calorimetry. It seems that unsaturated, but not saturated, free fatty acids reduce the lipid bilayer permeability to dithionite and iodide ions at the main phase transition of DMPC, without altering the thermodynamic properties of the bilayer.

Dimyristoylphosphatidylcholine↗
PubMed2000

Automated computerized intensive care unit severity of illness measure in the Department of Veterans Affairs: preliminary results. SISVistA Investigators. Scrutiny of ICU Severity Veterans Health Sysyems Technology Architecture.

OBJECTIVE: To evaluate the feasibility of an automated intensive care unit (ICU) risk adjustment tool (acronym: SISVistA) developed by selecting a subset of predictor variables from the Acute Physiology and Chronic Health Evaluation (APACHE) III available in the existing computerized database of the Department of Veterans Affairs (VA) healthcare system and modifying the APACHE diagnostic and comorbidity approach. DESIGN: Retrospective cohort study. SETTING: Six ICUs in three Ohio Veterans Affairs hospitals. PATIENT SELECTION: The first ICU admission of all patients from February 1996 through July 1997. OUTCOME MEASURE: Mortality at hospital discharge. METHODS: The predictor variables, including age, comorbidity, diagnosis, admission source (direct or transfer), and laboratory results (from the +/- 24-hr period surrounding admission), were extracted from computerized VA databases, and APACHE III weights were applied using customized software. The weights of all laboratory variables were added and treated as a single variable in the model. A logistic regression model was fitted to predict the outcome and the model was validated using a boot-strapping technique (1,000 repetitions). MAIN RESULTS: The analysis included all 4,651 eligible cases (442 deaths). The cohort was predominantly male (97.5%) and elderly (63.6 +/- 12.0 yrs). In multivariate analysis, significant predictors of hospital mortality included age (odds ratio [OR], 1.06; 95% confidence interval [CI], 1.04-1.09), comorbidity (OR, 1.11; 95% CI, 1.08-1.15), total laboratory score (OR, 1.07; 95% CI, 1.06-1.08), direct ICU admission (OR, 0.39; 95% CI, 0.31-0.49), and several broad ICU diagnostic categories. The SISVistA model had excellent discrimination and calibration (C statistic = 0.86, goodness-of-fit statistics; p > .20). The area under the receiver operating characteristic curve of the validated model was 0.86. CONCLUSIONS: Using common data elements often found in hospital computer systems, SISVistA predicts hospital mortality among patients in Ohio VA ICUs. This preliminary study supports the development of an automated ICU risk prediction system on a more diverse population.

APACHE↗
PubMed2000

Effect of calcium or 25OH vitamin D3 dietary supplementation on bone loss at the hip in men and women over the age of 60.

Dietary supplements that prevent bone loss at the hip and that can be applied safely in the elderly are likely to reduce hip fractures. A daily dietary supplement of 750 mg calcium or 15 microg 25OH vitamin D3 on bone loss at the hip and other sites, bone turnover and calcium-regulating hormones were studied over 4 yr in elderly volunteers using a randomized, double-blind, placebo-controlled trial. Bone mineral density (BMD) was measured by dual x-ray absorptiometry and bone structure by radiographs. Calcium biochemistry and bone turnover markers were measured in blood and urine. The 316 women entering the trial had a mean age of 73.7 yr and the 122 men of 75.9 yr. Baseline median calcium intake was 546 mg/day, and median serum 25OH vitamin D3 was 59 nmol/L. On placebo, loss of BMD at total hip was 2% and femoral medulla expansion was 3% over 4 yr. Calcium reduced bone loss, secondary hyperparathyroidism, and bone turnover. 25OH vitamin D3 was intermediate between placebo and calcium. Fracture rates and drop-out rates were similar among groups, and there were no serious adverse events with either supplement. A calcium supplement of 750 mg/day prevents loss of BMD, reduces femoral medullary expansion, secondary hyperparathyroidism, and high bone turnover. A supplement of 15 microg/day 25OH vitamin D3 is less effective, and because its effects are seen only at low calcium intakes, suggests that its beneficial effect is to reverse calcium insufficiency.

Aged↗
PubMed1999

Synchronous and asynchronous brain-state-in-a-box information system neural models.

Synchronous and asynchronous information system neural models are proposed that are hybrids of Pawlak's information system and Brain-State-in-a-Box (BSB) neural models. The stability of the proposed models is studied using LaSalle's Invariance Principle. Applications to an analysis of the United Nations activities are presented as examples.

Information Systems↗
PubMed1998

Obstructive sleep apnea syndrome in a family with Crouzon's syndrome.

Craniofacial anomalies are recognized causes of obstructive sleep apnea syndrome (OSAS) in children. Current literature is limited due to rarity of cases. Furthermore, the mechanism of upper airway obstruction is not clearly understood. We would like to report a family (father and 2 sons) who are suffering from Crouzon's syndrome. The two brothers (ages 1 and 3) were found to have significant obstructive sleep apnea syndrome (OSAS) with failure to thrive. Nasal continuous positive airway pressure (CPAP) markedly improved their OSAS and resulted in accelerated weight gain. The nasoendoscopy and magnetic resonance imaging (MRI) scan taken during natural sleep showed that choanal stenosis, maxillary hypoplasia, posteriorly displaced tongue, lengthened soft palate and adenoid tissues were important in the pathogenesis of upper airways obstruction in Crouzon's syndrome. Nasal CPAP improved airway obstruction by opening a narrow slit as demonstrated by MRI. Our results suggest that OSAS occurred in children with Crouzon's syndrome and that nasal CPAP was a useful treatment modality.

Adult↗
PubMed1998

The relationships between age, sex, and the incidence of dementia and Alzheimer disease: a meta-analysis.

BACKGROUND: Prevalence studies on dementia and Alzheimer disease (AD) have reported a positive association with age. However, the trend of the association in the oldest-old categories has been the subject of discussion. The relationship between sex and AD has been inconsistent with these studies. Prevalence rates are influenced by the survival and disease incidence. Incidence rates provide a better measure of disease risk. METHODS: English-language articles identified through a MEDLINE search on "incidence dementia" and "incidence Alzheimer's disease" were examined and references from identified articles were reviewed. Population-based studies using personal interviews, standard clinical diagnosis criteria (DSM-III for dementia, National Institute of Neurological and Communicative Disorders and Stroke-Alzheimer's Disease and Related Disorder Association for AD) and reporting age-specific incidence rates were included in the meta-analysis. Data from the selected studies were extracted and verified. Mixed-effect models were used in the meta-analysis to accommodate the heterogeneity of the studies. RESULTS: Incident dementia and AD are associated with a significant quadratic age effect indicating that the increase in incidence rates slows down with the increase in age, although there is no sign of a decline in the incidence rates themselves. The odds ratios for women to develop incidence of dementia and AD relative to men are 1.18 (95% confidence interval, 0.95-1.46) and 1.56 (95% confidence interval, 1.16-2.10), respectively. CONCLUSIONS: The acceleration of incidence rates for AD and dementia slows down with the increase in age, although we find no evidence of a rate decline. Women are at higher risk of developing AD than men.

Age Factors↗
PubMed1998

Bone mass and structure at the hip in men and women over the age of 60 years.

Bone mass and structure at the proximal femur are important predictors of hip fracture. The aims of this study were to compare in a large sample of elderly men and women the precision of measurements of bone mass and structure at multiple sites at the proximal femur, to examine their interrelationships, to establish their relationships with age and body size, and to examine criteria for defining geometric and architectural variables in bone structure. Women (n = 336) and men (n = 141) over the age of 60 years were studied cross-sectionally. Bone mineral density (BMD) and content (BMC) at the proximal femur were measured in duplicate by dual-energy X-ray absorptiometry (DXA). Shaft and total upper femur (hip) sites in addition to femoral neck, Ward's triangle and trochanter were measured. Structural variables, measured from radiographs and from DXA images, including cortical thickness at calcar femorale, lateral cotex and midfemur, width of the femur and medulla, Singh grade, hip and femoral axis length, femoral head and neck width and the center of mass of the femoral neck. BMD and BMC had high reproducibility and there were significant differences in reproducibility across sites. Among sites, total upper femur and shaft had the highest reproducibility. Duplicate measurements substantially improved reliability of the measurement and are recommended when the value is close to a diagnostic level or when it will be used to establish rates of change. Reproducibility of structural variables was also high except for the lateral cortex, center of mass and Singh grade. Variance due to measurement error did not change with either age or gender. Women were significantly different from men, after controlling for differences in body size, in all variables except Singh grade and medulla width. BMD and BMC were negatively related to age and positively to body size. Structural variables examined in relation to age and body size fell into two categories. The first comprised variables that were not age-related but were body-size-related suggesting that they could be classified as geometric variables. The second comprised variables that were both body-size-related and age-related, suggesting that they could be classified as architectural variables. Using these criteria, calcar and lateral cortex were architectural variables, whereas shaft width, hip and femoral axis length, femoral head and neck width, and center of mass were geometric in both men and women. In women, shaft cortex width and medulla width were age-related, whereas in men they were not. Singh grade showed no consistent pattern with age or body size in women and men.

Absorptiometry, Photon↗