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Biomedical subjects

J Woo

Publications and source records attributed to J Woo.

At least 55 records · Page 3Linked to original sources
PubMed2002

Total daily energy expenditure in wasted chronic obstructive pulmonary disease patients.

OBJECTIVES: To investigate total daily energy expenditure in chronic obstructive pulmonary disease (COPD) patients during a rehabilitation programme. DESIGN: Observational study involving a case and a control group. SUBJECTS: Ten COPD patients (six with body mass index (BMI) <18.5 kg/m(2) and four with BMI >18.5 kg/m(2)) were evaluated for their energy expenditure profile. Four additional healthy age-matched volunteers were also included for methodology evaluation. INTERVENTIONS: Measurements of total daily energy expenditure (TEE), resting energy expenditure (REE) and diet-induced thermogenesis (DIT) and energy intake were undertaken by indirect calorimetry and bicarbonate-urea methods and dietary records. RESULTS: REE in COPD patients was not significantly different from that predicted by the Harris-Benedict equation. Before the exercise day the mean TEE was 1508 kcal/day and physical activity level (PAL as calculated by TEE/REE) was 1.52. On the exercise day the TEE increased to 1568 kcal/day and PAL was 1.60, but neither of these changes were significant. The energy cost of increased physical activity during rehabilitation exercise was estimated to be 191 kcal/day. No significant change was found in DIT between the two patient groups. However, overall energy balances were found to be negative (-363 kcal/day). CONCLUSION: The rehabilitation programme did not cause a significant energy demand in COPD patients. TEE in COPD patients was not greater than in free-living healthy subjects. Patients, who were underweight, did not have a higher TEE than patients with normal weight. This suggested that malnutrition in COPD patients was not due to an increased energy expenditure. On the other hand, a significant negative energy balance due to insufficient energy intake was found in seven out of 10 patients.

Aged↗
PubMed2002

Is waist circumference a useful measure in predicting health outcomes in the elderly?

OBJECTIVE: To examine the effect of age on the relationship between body mass index (BMI) and waist circumference (WC), and the usefulness of BMI, WC and waist-hip ratio (WHR) in predicting mortality and cardiovascular risk in the elderly population. DESIGN: Longitudinal observational study of 36 months duration. SUBJECTS AND METHOD: A stratified random sample of 2,032 Chinese subjects (990 male, 1,033 female) mean age (s.d.) 80.1 (7.5), interviewed and examined at baseline and after 36 months. Deaths and presence of diabetes mellitus and hypertension were documented. A younger data set of 1,010 subjects (500 male, 510 female), mean age (s.d.) 45.5 (11.6), was used for comparison of the BMI-WC relationship between younger and older subjects. In predicting outcomes using different values of BMI, WC and WHR, receiver operating characteristic curve analysis was used to derive cut-off values with optimal sensitivity and specificity, and the likelihood ratios for mortality, diabetes and hypertension for different anthropometric values were plotted. RESULTS: The waist circumference values corresponding to BMI values of 25 and 30 kg/m(2) were higher in elderly (92 and 103 cm for men; 88 and 99 cm for women) compared with younger subjects (85 and 97 cm for men; 78 and 88 cm for women). BMI and WC are inversely associated with mortality, in both men and women, positively associated with diabetes in men but not in women. WC was positively associated with hypertension in men and women. WHR was not associated with any outcome measures. The anthropometric measurement at the point of intersection of the likelihood curves for mortality and diabetes may be considered the optimum value, being BMI=21 kg/m(2) for men and 25 kg/m(2) for women, WC between 80 and 85 cm, and WHR 0.88-0.90. CONCLUSION: Waist measurement values for predicting health outcomes in elderly people aged 70 y and over are different compared with younger subjects, and have similar predictive accuracy compared with body mass index. Waist-hip ratio is not a useful predictor.

Aged↗
PubMed2002

Prevalence of wheeze, bronchial hyper-responsiveness and asthma in the elderly Chinese.

BACKGROUND: Asthma is a common health problem affecting patients of all ages. Because of the ease of sampling, epidemiological studies have concentrated mainly on the paediatric and general population. OBJECTIVE: This study aimed to determine the prevalence of wheeze, bronchial hyper-responsiveness and asthma amongst our elderly population and deduce any clinical and laboratory risk factors that might identify elderly asthmatics at an earlier stage. METHODS: Two thousand and thirty-two elderly Chinese aged > or = 70 years, randomly selected from a registered list of all recipients of Old Age and Disability Allowances in Hong Kong, were administered a questionnaire on lung health. Two hundred and fifty subjects were invited to attend our laboratory for skin tests and pulmonary function tests and 179 agreed. Of these, 173 (96.6%) and 176 (98.3%) had eosinophil count and serum IgE levels measured, respectively. Two definitions of asthma were used: (1) bronchial hyper-responsiveness (BHR) plus current wheeze, and (2) history of wheezing without previous diagnostic labels of emphysema or chronic bronchitis. RESULTS: Fifteen patients (out of 179: 8.4%) reported wheezing over the past 1 year. Fifty-one patients (28.5%) demonstrated BHR on spirometry or histamine challenge tests. Seven patients had both symptoms of wheezing and evidence of BHR. The prevalence of asthma using this definition is therefore 3.9% (95% CI 1.6-7.9%). Nine patients had symptoms of wheezing without previous diagnostic labels of chronic bronchitis or emphysema and, using this definition, the prevalence is 5.0% (95% CI 2.3-9.3%). Using multiple logistic regression studies, sex, social class, age, smoking habits, serum IgE levels and eosinophil counts did not predict a diagnosis of asthma using either definition. We found no association between a positive skin test and any respiratory symptoms or illnesses including asthma. CONCLUSION: Wheeze, bronchial hyper-responsiveness and asthma are prevalent amongst our elderly population. However, there were no identifiable demographic and laboratory risk factors in this study that may help us predict a diagnosis of asthma.

Aged↗
PubMed2002

Thermoluminescence of PbWO4 irradiated with UV light.

PbWO4 single crystals were grown by the Czochralski method in argon and air. The glow curves induced by UV light and the absorption spectra of PbWO4 annealed at various temperatures were measured. The glow curves of PbWO4 were strongly dependent on the growing atmospheres. The activation energies of the 110 K peak of PbWO4 grown in argon and the 122 K peak of PbWO4 grown in air were calculated to be 0.23 eV and 0.29 eV, respectively. The ratio of the 2.76 eV emission band to the 2.48 eV or 2.26 eV emission bands of the PbWO4 grown in air was smaller than that of the PbWO4 grown in argon. The glow curve of PbWO4 grown in argon was similar to that of PbWO4 grown in air when the annealing temperatures were increased.

Air↗
PubMed2001

Virulence differences between two field isolates of feline immunodeficiency virus (FIV-APetaluma and FIV-CPGammar) in young adult specific pathogen free cats.

The goal of this study was to identify a strain of feline immunodeficiency virus (FIV) that would be more virulent for adult cats than the prototype FIV-APetaluma and, thereby, enhance the FIV infection model for HIV-1 related research. Diehl et al. reported that one clade C strain of FIV, FIV-CPGammar, was more virulent than other known FIV isolates. Mortalities from 58 to 100% were reported for kittens 12 weeks of age and less following intravenous inoculation. A more variable and somewhat less virulent disease course was observed in neonatal to 8-10-week-old kittens infected orally, intravaginally or intrarectally with this same isolate (Obert and Hoover, 2000). However, no studies have been done with FIV-CPGammar in adult cats. Therefore, the virulence of FIV-CPGammar for young adult cats was compared to that of FIV-APetalulma, the original FIV isolate. One group of five cats were inoculated intraperitoneally with 470 TCID(50) of FIV-CPGammar in the form of pooled plasma from acutely infected cats, while a second group was infected with plasma containing the 750 TCID50 of FIV-APetaluma. The cats were observed for 20 weeks for gross signs of disease, hematologic abnormalities, time of antibody appearance, and plasma and peripheral blood mononuclear cell (PBMC) associated virus levels. Viral RNA and proviral DNA were measured by a real-time PCR, sensitive to 50 copies per milliliter. The only outward sign of disease was lymphadenopathy, which occurred at a similar time and intensity in both groups of cats. Cats infected with FIV-CPGammar were more likely to be neutropenic and lymphopenic during the first 10-12 weeks of infection than cats infected with FIV-APetaluma. Both groups of cats showed similar overall declines in absolute mean CD4 cell counts and identical concomitant increases in CD8 cells. CD4/CD8 cell ratios were also similar. Antibody, as measured by an ELISA against recombinant FIV-TM antigen, appeared in all cats by 4 weeks post-infection. The most significant differences were in plasma viral RNA and PBMC proviral DNA levels. Cats infected with FIV-CPGammar had up to 100 times higher mean levels of viral RNA during the first few weeks of infection than cats infected with FIV-APetaluma. This difference was also mirrored in levels of proviral DNA in PBMC, which were significantly higher in the FIV-CPGammar infected cats. Plasma viral RNA and PBMC proviral DNA levels were virtually identical in both groups of cats at 20 weeks post-infection. However, proviral DNA in tissues such as thymus and popliteal lymph nodes was 10-fold or so higher in FIV-CPGammar infected cats at 20 weeks and histopathologic lesions were more severe. Based on these various parameters, we concluded that FIV-CPGammar was more virulent than FIV-APetaluma in young adult cats during the 20-week study period. However, we were not able to recreate the severe and rapidly progressive disease previously reported for kittens, suggesting an age-related resistance similar to that observed previously for FIV-APetaluma (George et al., 1993).

Animals↗
PubMed2001

Structural basis of the redox switch in the OxyR transcription factor.

The Escherichia coli OxyR transcription factor senses H2O2 and is activated through the formation of an intramolecular disulfide bond. Here we present the crystal structures of the regulatory domain of OxyR in its reduced and oxidized forms, determined at 2.7 A and 2.3 A resolutions, respectively. In the reduced form, the two redox-active cysteines are separated by approximately 17 A. Disulfide bond formation in the oxidized form results in a significant structural change in the regulatory domain. The structural remodeling, which leads to different oligomeric associations, accounts for the redox-dependent switch in OxyR and provides a novel example of protein regulation by "fold editing" through a reversible disulfide bond formation within a folded domain.

Bacterial Proteins↗
PubMed2001

A 2.1 A resolution structure of an uncleaved alpha(1)-antitrypsin shows variability of the reactive center and other loops.

Serpin (serine protease inhibitor) proteins are involved in diverse physiological processes including inflammation, coagulation, matrix remodeling, and cell differentiation. Deficiency of normal serpin functions leads to various hereditary diseases. Besides their clinical importance, serpin proteins draw much attention due to the large conformational changes that occur upon interaction with proteases. We present here the crystal structure of an uncleaved alpha(1)-antitrypsin determined by the multiple isomorphous replacement method and refined to 2.1 A resolution. The structure, which is the first active serpin structure based on experimental phases, reveals novel conformations in the flexible loops, including the proximal hinge region of the reactive center loop and the surface cavity region in the central beta-sheet, sheet A. The determined loop conformation explains the results of recent mutagenesis studies and provides detailed insights into the protease inhibition mechanism. The high-resolution structure of active alpha(1)-antitrypsin also provides evidence for the existence of localized van-der-Waals strain in the central hydrophobic core.

Amino Acid Sequence↗
PubMed2001

Telepsychiatry in psychogeriatric service: a pilot study.

A pilot study on telepsychiatry was conducted in which a videoconferencing link was established between a regional hospital and a care and attention home. Using this system, a psychogeriatric outreach team provided 149 psychiatric assessments to 45 residents of the care and attention home over 11 months. Videoconferencing was found to be highly feasible. It was acceptable to staff and patients and more cost-effective than on-site visits.

Aged↗
PubMed2001

Population bone mineral density measurements for Chinese women and men in Hong Kong.

The aim of the study was to establish population ranges of bone mineral density (BMD) for Hong Kong Chinese men and women for the Hologic QDR 2000 bone densitometer, to compare these values with the manufacturer's reference ranges, to compare these values with population ranges for women obtained for the Norland X26 bone densitometer, and to examine variations between the two densitometers. The subjects were 164 men aged 40-79 years and 436 women aged 20-89 years, who were all ethnic Chinese, recruited from volunteers, social centers for the elderly and general practice clinics. BMD in women began to decline rapidly between ages 50 and 79 years, averaging about 10% loss per decade from the young adult (20-29 years) mean. The percentage losses from young adult mean values in the spine, femroal neck, trochanter and total femur were 23%, 30%, 31% and 33%, respectively, from 20 to 79 years. In the ninth decade no further decrease in BMD occurred with the exception of a further 4% at the hip sites. In men, no decrease in spine BMD occurred between 40 and 70 years. Compared with BMD in the fourth decade, 10%, 13%, and 11% of BMD was lost at the femoral neck, trochanter and total femur, respectively, by the seventh decade. These values show differences compared with the manufacturer's reference ranges for Caucasians and Japanese. BMD values for the spine were comparable between Hologic and Norland densitometers, but Hologic values for femoral neck and trochanteric regions were lower than the Norland values. Data provided by this study may thus be used as normative values for the Hologic QDR2000 bone densitometer, instead of values provided by the manufacturer. BMD values at the hip sites are not interchangeable between Norland and Hologic bone densitometers, and estimation of numbers of the population with osteoporosis will depend on the model of densitometer used.

Absorptiometry, Photon↗
PubMed2001

Estrogen receptor gene polymorphism and bone mineral density in postmenopausal Chinese women.

PvuII and XbaI restriction fragment length polymorphisms (RFLPs) for the estrogen receptor gene (ERG) and its relation to bone mineral density (BMD) were examined in 454 postmenopausal Chinese women, aged 55-79 years. The RFLPs were represented as P or p (PvuII) and X or x (XbaI), with capital letters signifying the absence of and small letters the presence of restriction sites. There was no significant difference in BMD between the PP, Pp, and pp genotypes. However, women of the XX genotype had significantly higher BMD at the spine than women of the Xx or xx genotype. The magnitude of the difference in BMD was 80% of a standard deviation (SD) for BMD in elderly women and 40% of a SD in postmenopausal women. There was no statistically significant interaction between the PvuII genotype and the XbaI genotype in determining BMD. We conclude that postmenopausal Chinese women who were homozygous for the XX genotype had slightly higher BMD than the others. However, the difference in BMD was small and was unlikely to have any clinical significance. The ERG is not a major determinant of BMD in Chinese women in Hong Kong.

Aged↗
PubMed2001

Alendronate for the prevention of bone loss in patients on inhaled steroid therapy.

One hundred women on inhaled steroid therapy (dose range from 800 to <1600 microg per day) were randomized to receive 10 mg of oral alendronate or placebo (with 500 mg of calcium in the form of daily calcium carbonate). Bone mineral density (BMD) was measured at baseline, 6 months, and 12 months. The percentage changes in BMD were -0.80% in the placebo group and 2.99% in the alendronate group at the spine (p < 0.001 by analysis of covariance [ANCOVA]), and were -0.51% in the placebo group and 0.97% in the alendronate group at the femoral neck (p < 0.05 by ANCOVA). Five patients in the alendronate-treated group, and a similar number of patients in the placebo group, complained of mild gastric discomfort. We conclude that women on inhaled steroid therapy were at risk of accelerated bone loss, which could be prevented by a daily dose of 10 mg of alendronate.

Administration, Inhalation↗
PubMed2001

Prediction of body fat by anthropometry in older Chinese people.

OBJECTIVE: To derive regression equations for fat percentage by using simple anthropometric measurements applicable in normal and immobile (cannot stand or walk) older people. RESEARCH METHODS AND PROCEDURES: The study population comprised 352 females and 261 males, apparently well and community-dwelling, aged 69 to 82 years. Fifty-one females and 27 males were recruited for external validation. Body weight, standing height, arm span, triceps and biceps skinfold thicknesses (SFTs), and midarm circumference were measured. The reference method of total body fat percentage was dual-energy X-ray densitometry. Predictive equations for fat percentages were derived by stepwise multiple linear regression on anthropometric indices and gender. RESULTS: Upper-limb SFTs, body mass index, and gender yielded the more predictive equation. The SEE was 4.1% weight. There was a significant trend of underestimation in overweight subjects, especially in females. The equation using SFTs and midarm circumference was less reliable but more applicable to older immobile people and those with significant kyphoscoliosis. CONCLUSIONS: The combination of body mass index and upper-limb SFTs gives reliable prediction of fat percentages in older Chinese people, except in the obese.

Absorptiometry, Photon↗
PubMed2001

The Mediterranean score of dietary habits in Chinese populations in four different geographical areas.

OBJECTIVE: To compare the dietary intake of Chinese people living in Pan Yu, Hong Kong, San Francisco and Sydney with respect to cardiovascular health, using the Mediterranean diet score, examining the effects of age, gender, urbanization and acculturation on the diet score. SUBJECTS: A total of 500 men and 510 women in Hong Kong were recruited as a territory-wide stratified random sample. Subjects were recruited in response to local advertisements for the other three sites: Pan Yu, 58 men, 95 women; San Francisco, 166 men, 192 women; Sydney, 95 men, 73 women. METHOD: Food-frequency questionnaire over a 7 week period. A high/healthy score was taken as > or =4 for men and >3 for women, representing a dietary pattern beneficial for cardiovascular health. RESULTS: In Hong Kong, more women in the middle age group (35-54) had a high score than other age groups, and overall more women had high scores than men. In comparing the four geographical regions, Pan Yu had the highest number of subjects with high score, and Hong Kong had the lowest. With the exception of the younger population and men in Hong Kong, the percentage of the population with a high score in all sites is greater than among elderly Greeks consuming a more traditional heart-healthy Mediterranean diet. CONCLUSION: Considerable variations in Chinese dietary patterns exist with respect to age, gender and geographic location. Overall, the Chinese diet is comparable to the Mediterranean diet and may be expected to have similar health benefits that have been documented for the traditional Mediterranean diet.

Adult↗
PubMed2001

Obesity, insulin resistance and isolated low high-density-lipoprotein cholesterol in Chinese subjects.

AIM: Recent studies have shown that the risk of developing coronary heart disease in subjects with 'isolated low high-density-lipoprotein cholesterol (HDL-C)' (defined as HDL-C < 0.9 mmol/l and total cholesterol (TC) < 5.2 mmol/l) was similar to those with hypercholesterolaemia. We examined the prevalence of isolated low HDL-C in Hong Kong Chinese and its relationship with insulin resistance and triglyceride (TG) level. METHODS: Hong Kong Chinese subjects (n = 1493) recruited in a population-based prevalence survey for cardiovascular risk factors were examined. Insulin resistance was calculated using a computer-solved homeostasis model assessment method. RESULTS: Of the 1493 subjects, 72 (4.8%) had isolated low HDL-C, in whom half (n = 36) had TG > or = 1.7 mmol/l and half (n = 36) had TG < 1.7 mmol/l. Compared with the 'controls' (subjects with TC < 5.2 mmol/l and HDL-C > or = 0.9 mmol/l; TC > or = 5.2 mmol/l and HDL-C < 0.9 mmol/l; or TC > or = 5.2 mmol/l and HDL-C > or = 0.9 mmol/l, n = 1421), subjects with isolated low HDL-C and high TG were more obese, had higher plasma glucose, fasting and 2 h plasma insulin concentrations and insulin resistance. Subjects with isolated low HDL-C and TG < 1.7 mmol/l had similar insulin concentrations and insulin resistance, but were more obese than the 'controls'. Subjects with isolated low HDL-C and high TG also had higher fasting PG, insulin and insulin resistance than those with isolated low HDL-C and low TG. CONCLUSIONS: In this population-based study, 4.8% of Hong Kong Chinese had isolated low HDL-C, which was closely associated with obesity. The coexistence of high TG suggests an insulin-resistant state.

Adult↗
PubMed2001

Longitudinal changes in body mass index and body composition over 3 years and relationship to health outcomes in Hong Kong Chinese age 70 and older.

OBJECTIVES: To determine longitudinal changes in body mass index (BMI) and body composition with age and the relationship between these changes with mortality, morbidity, functional capacity, and other health outcome measures. DESIGN: A 3-year longitudinal study of a random sample of community-living subjects. SETTING: Older Chinese in the Hong Kong Special Administrative Region of China. PARTICIPANTS: Two thousand and thirty-two Chinese subjects age 70 and older recruited territory-wide by proportional random sampling. MEASUREMENTS: Baseline information collected included medical history, self-perceived health, Barthel Index, Geriatric Depression Score, time taken to complete a 16-foot walk, height, weight, mid-arm circumference, arm skin-fold thickness, and waist/hip ratio. Body composition was calculated from prediction equation. Outcome measures included mortality, development of new diseases, Barthel Index, time taken for 16-foot walk, self-perceived health, and Geriatric Depression Score. RESULTS: All parameters, with the exception of triceps skin-fold thickness in men, decreased, regardless of presence or absence of disease. The decrease in arm circumference, triceps skin-fold thickness, and total body fat (TBF) was greater in women than in men, whereas men had a greater decrease in fat-free mass (FFM). Even in the absence of disease, three times as many subjects lost > or =5kg in weight as gained > or =5kg (15% vs. 5%), and only age could be identified as a contributing factor to this weight loss. In the absence of disease, lower anthropometric indices were associated with greater mortality, development of new disease (in women only), dependency, and poor performance measure. Waist-hip ratio was not associated with mortality or any other health outcomes. Decrease in both FFM and TBF were associated with worse outcomes, the effect being more marked in women. CONCLUSION: In the older population, changes in weight and body composition occur even in the absence of disease and are associated with mortality and physical functioning level. Weight loss rather than weight gain appears to be more important in this population, and promotion of life-style interventions targeted at weight maintenance would be important.

Activities of Daily Living↗
PubMed2001

Falls among Chinese stroke patients during rehabilitation.

OBJECTIVE: To investigate the incidence, circumstances, and risk factors of falls among Chinese stroke patients during inpatient rehabilitation. DESIGN: Historical cohort study. SETTING: A 25-bed stroke rehabilitation unit in Hong Kong. PARTICIPANTS: Six hundred seventy-seven patients admitted consecutively to the unit approximately 1 week after acute stroke. INTERVENTIONS: All patients received conventional rehabilitation therapies, and a protocol to analyze the causes of falls and to advise on prevention was followed in the unit. MAIN OUTCOME MEASURES: A fall was defined as any unplanned "touch to the floor" of any part of a patient's body, excluding the feet. The fall rate and circumstances were studied. Demography, Abbreviated Mental Test score, Barthel Index score on admission, urinary incontinence, dysphasia, hemiplegia, hemiparesthesia, vision and hearing impairment, and the risk factors of stroke were analyzed by logistic regression for their relation to falls. RESULTS: Seventy-eight patients (11.5%) had falls. The fall rate was 5.5 per 1000 patient days. Eighty-five percent of the falls occurred in daytime and 71% at the bedside. Moderate to severe disability on the Barthal Index admission (6-14) and dysphasia were associated with an increased risk of falls (odds ratio [OR] = 2.64; 95% confidence interval [CI], 1.26-5.51; OR = 1.81; 95% CI, 1.03-3.17, respectively). CONCLUSIONS: Stroke patients in China had a significant fall rate during rehabilitation, but it was lower than rates reported in the Western stroke populations. The fall protocol followed in our unit might have reduced the incidence of repeated falls. The circumstances of falls were, however, similar. Moderate to severe disability on admission and dysphasia were 2 independent predictors for falls, and more intensive fall prevention efforts should focus on this group of patients.

Accidental Falls↗