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Biomedical subjects

W Chan

Publications and source records attributed to W Chan.

At least 55 records · Page 3Linked to original sources
PubMed1999

Prediction of community integration and vocational outcome 2-5 years after traumatic brain injury rehabilitation in Australia.

OBJECTIVES: To predict community integration and vocational outcomes 2-5 years after traumatic brain injury (TBI). DESIGN: Multivariate correlational design incorporating retrospective data collection and questionnaire follow-up. METHODS: Four hundred and forty six patients admitted to a Head Injury Unit between 1991 and 1995 were contacted. Data on predictor variables (demographic, injury severity and functional) were retrieved from hospital records. Community integration and vocational outcome was assessed by self-administered questionnaire. Two hundred and nine patients/carers completed and returned the questionnaires. Mean follow-up was 3.5 years. Data were analysed by descriptive statistics, multiple regression and discriminant analysis using SPSS. RESULTS: Community integration was predicted by age, disability level and cognition. Length of PTA, cognition, disability levels, GCS, functional status, length of acute stay and prior occupation discriminated those who returned to work. A total of 46.5% returned to work with 74.5% in the same or similar jobs. CONCLUSION: Long term outcomes post-TBI can be predicted by demographic, injury severity and functional status variables.

Activities of Daily Living↗
PubMed1999

Continuing drug therapy while breastfeeding. Part 1. Common misconceptions of patients.

QUESTION: Some of my patients who need specific drugs during the postpartum period are hesitant to breastfeed even when I tell them that, according to available evidence, these drugs are safe. Am I right about this and how should I advise my patients? ANSWER: Recent studies reveal that women receiving chronic therapy tend to initiate breastfeeding much less often than mothers in the general population and, if they do initiate, discontinue it much earlier. While reassuring counseling is generally correlated with continuation of breastfeeding, women receiving chronic medications still discontinue breastfeeding earlier. Stressing the clear benefits of breastfeeding and the lack of apparent risk of drugs shown to be safe should be coupled with repeated reassurance to mothers during close follow up of their babies.

Adult↗
PubMed1998

Comparison of reported symptoms of acute myocardial infarction in Mexican Americans versus non-Hispanic whites (the Corpus Christi Heart Project).

This study examines whether there are differences between Mexican Americans and non-Hispanic whites in reported symptoms of acute myocardial infarction (AMI). The symptoms experienced by patients identified in a community-based surveillance program were examined to determine whether between-group differences existed by ethnicity, gender, and diabetic status. Data were available regarding the symptoms of 589 patients, between the ages of 25 and 74 years, who were hospitalized and diagnosed as either having definite or possible AMI in special care units at 1 of 7 hospitals in Corpus Christi, Texas. The most frequently reported symptoms were chest pain (83.2%), chest pressure or discomfort (67.6%), sweating (64.2%), fatigue (62.6%), dyspnea (60.3%), and arm or jaw pain (58.2%). After adjusting for age, diabetes mellitus, and gender, and relative to non-Hispanic whites, Mexican Americans were more likely to report chest pain, upper back pain, and palpitations, and less likely to report arm or jaw pain. Likewise, relative to men, women were more likely to report fatigue, dyspnea, dizziness, upper back pain, palpitations, and cough, and were less likely to report chest pain. Significant differences were also observed when older patients' symptoms were compared with younger patients' symptoms.

Adult↗
PubMed1998

alpha-Tocopherol reduces proteinuria, oxidative stress, and expression of transforming growth factor beta 1 in IgA nephropathy in the rat.

Oxidative stress and the fibrogenic cytokine transforming growth factor beta 1 (TGF beta 1) have been implicated in the pathogenesis and progression of IgA nephropathy. In the present study, we used alpha-tocopherol as a dietary supplement to test the hypothesis that the proteinuria, oxidative stress, and TGF beta mRNA can be more effectively lowered with higher doses of alpha-tocopherol. Hematuria, proteinuria, and mesangial IgA deposition are parameters which characterize IgA nephropathy. IgA nephropathy was induced by bovine gamma globulin oral immunization in rats during an 8-week course, and all hallmarks of IgA nephropathy were produced in this 8-week animal model. The elevation in renal malondialdehyde content and TGF beta 1 mRNA, as well as the severity of proteinuria, was blunted by alpha-tocopherol. Our data suggested that conventional dosage of alpha-tocopherol at 100 IU/kg chow lowered kidney TGF beta 1 to control values and increasing the dose by 2 1/2-fold or even 5-fold resulted in no further reduction in TGF beta 1 mRNA. Significant reduction of proteinuria was achieved better with a dose of 250 IU/kg chow of alpha-tocopherol supplementation than with the 100 IU/kg chow. We conclude that alpha-tocopherol at this dose is efficacious in controlling proteinuria, downregulating TGF beta 1, and reducing oxidative stress in experimental IgA nephropathy. Doubling this dose achieved no further benefits.

Animals↗
PubMed1998

Statistical design of REACT (Rapid Early Action for Coronary Treatment), a multisite community trial with continual data collection.

Unusual problems in statistical design were faced by Rapid Early Action for Coronary Treatment (REACT), a multisite trial testing a community intervention to reduce the delay between onset of symptoms of acute myocardial infarction (MI) and patients' arrival at a hospital emergency department. In 20 pair-matched U.S. communities, hospital staff members recorded delay time throughout a 4-month baseline period and the subsequent 18-month intervention period, during which one randomly selected community of each pair received a campaign of public and professional education. To exploit the continual nature of its data-collection protocol, REACT estimated the trend of delay time separately in each community by linear regression, adjusting for age, sex, and history of MI, and compared the ten adjusted slopes from intervention communities with those from control communities by a paired t-test. Power calculations based on the analytical model showed that with K=600-800 cases per community, REACT would have 80% power to demonstrate a differential reduction of 30 min in mean delay time between intervention and control communities, as well as effects on a variety of secondary outcomes. Sensitivity analysis confirmed that the number of communities was optimal within constraints of funding and that the detectable effect depended weakly on the effectiveness of matching but strongly on K, helping the investigators set operational priorities. The methodologic strategy developed for REACT should prove useful in the design of similar trials in the future.

Emergencies↗
PubMed1998

Infectious disease of the spine: outcome of rehabilitation.

Infectious disease of the spine is infrequently seen in the rehabilitation setting. We examined retrospectively 26 patients with spinal infections admitted to the rehabilitation centre over a 6-year period to determine the demographic characteristics, clinical features and outcome after rehabilitation. Their ages ranged from 24 to 83 years (mean = 56.4); 65.4% were males. The infection was due to pyogenic bacteria in 14 patients (53.8%) and Mycobacterium tuberculosis in 12 (46.2%). Staphylococcus aureus was the causative agent in 69% of those with pyogenic infections. A history of diabetes mellitus was present in 35.7% of the pyogenic group but in only 8.3% of the tuberculous group. Localised back pain, fever and neurological deficits were the typical clinical manifestations. The most common site of infection was the thoracic region. Surgery was performed on 24 patients and all received prolonged courses of antibiotics. All but three patients completed the rehabilitation programme. The motor score for the lower limbs and the modified Barthel scores for activities of daily living (ADL) and mobility improved significantly (P < 0.05) for both pyogenic and tuberculous groups. The amounts of improvement achieved were not significantly different between the pyogenic and tuberculous groups except for ADL. Age, gender and the presence of diabetes mellitus did not appear to significantly affect the neurological or functional outcome in our study population. The majority of patients (87.5%) were discharged to their own homes.

Activities of Daily Living↗
PubMed1998

Spinal injury rehabilitation in Singapore.

Traumatic spinal cord injuries (SCI) are often preventable. In order to determine the characteristics and rehabilitation outcome of our spinal injured, we carried out a retrospective study of SCI patients admitted between January 1990 and December 1995 to the only spinal rehabilitation centre in Singapore. There was a total of 231 patients with ages between 14 and 82 years. The majority (73.6%) were below the age of 50. There was a male preponderance (83.1%) and a significant proportion of foreigners (20.3%). The most common causes of injuries were falls (50.7%) and road traffic accidents (37.2%). Damage to the cervical spine predominated (53.7%), followed by the thoracolumbar junction (23.4%). At the end of rehabilitation, the number of patients who were Frankel D/E improved significantly from 61 to 136. Sixty-eight patients were able to ambulate independently without aid and total independence in activities of daily living was achieved in 45 patients. The majority (87.9%) were discharged to their own homes. Of those who returned for follow-up, 86.3% were gainfully employed at the time of injury but only 21.6% had returned to some form of vocation within 1 year.

Accidental Falls↗
PubMed1998

Predictors of ambulatory blood pressure: identification of high-risk adolescents.

Within a life span perspective on prevention, adolescence was conceptualized as a pivotal transition in the evolution of risk for hypertension and other cardiovascular morbidity. Resting blood pressure (BP), BP reactivity, and 24-hour ambulatory BP were measured in a multiethnic sample of 41 male and female adolescents aged 15 to 16 years old. Results were consistent with the hypothesis that BP levels during reactivity testing would be better predictors of ambulatory BP than levels of BP measured at rest using a standard protocol. Ethnic group differences in ambulatory BP were statistically significant. The findings warrant further study and may provide a means for early identification of adolescents at risk for developing high BP.

Adolescent↗
PubMed1998

Effects of fish oil and alpha-tocopherol in immunoglobulin A nephropathy in the rat.

Alpha-tocopherol and fish oil have been reported to modulate the progression of IgA nephropathy in animals and humans. Because fish oil has been reported to exacerbate renal disease in subtotal nephrectomized rats, we investigated the effects of fish oil, with and without alpha-tocopherol, on the course of IgA nephropathy. Experimental IgA nephropathy was induced in male Sprague-Dawley rats, weighing 170-200 g, by oral and i.v. immunization with bovine gamma-globulin for 8 wk. IgA nephropathy was evidenced by hematuria, proteinuria, and IgA deposition in the mesangium. Standard rodent chow, containing 30 IU of alpha-tocopherol/kg of diet, was given to the control and IgA nephropathy rats. Fish oil (20% wt/wt), stripped of alpha-tocopherol preservative, was given to control and a second group of IgA nephropathy rats. Alternatively, corn oil or fish oil was supplemented with alpha-tocopherol at 100 IU/kg of diet and given to the third and fourth groups of IgA nephropathy rats. All animals were killed at 8 wk. Urinary protein excretion, plasma and kidney alpha-tocopherol concentrations, as well as glomerular planar area, and kidney transforming growth factor-beta1 mRNA were analyzed. As determined by reductions in proteinuria, glomerular planar area, and TGF-beta1 mRNA, fish oil with alpha-tocopherol ameliorated the renal injury induced by bovine gamma-globulin, whereas fish oil without alpha-tocopherol did not. Our findings support the importance of alpha-tocopherol, more so than fish oil, in mitigating the injury and promoting repair in experimental IgA nephropathy.

Animals↗
PubMed1998

Glomerulosclerosis in the remnant kidney rat is modulated by dietary alpha-tocopherol.

Glomerulosclerosis and tubulointerstitial injury are characteristic features seen in the subtotal (5/6) nephrectomy remnant kidney model in the rat. Oxidative stress from renal mass reduction contributes to the glomerular and tubular injury. Previous studies have clearly demonstrated the prevention or inhibition of such injury by an antioxidant such as alpha-tocopherol. However, few data are available on the ability of alpha-tocopherol to modulate or arrest progression of the established disease. This study examines whether alpha-tocopherol modulates glomerulosclerosis and tubulointerstitial injury when it is given 2 wk after renal damage has been established. The findings indicate that alpha-tocopherol has the capacity to modulate both tubulointerstitial injury and glomerulosclerosis, lower the elevated expression of transforming growth factor-beta1, and reduce plasma and kidney malondialdehyde concentration, the end product of lipid peroxidation. The results support the potential utility of alpha-tocopherol in reversing established glomerulosclerosis and tubulointerstitial injury in a remnant kidney model.

Animals↗
PubMed1998

Allelic deletion analyses of MMAC/PTEN and DMBT1 loci in gliomas: relationship to prognostic significance.

The frequency of loss of heterozygosity (LOH) around MMAC/PTEN and DMBT1 loci and survival analyses based on the LOH status were assessed in 110 patients with different histological groups of gliomas. Twenty-six of the patients had anaplastic oligodendrogliomas, 31 had anaplastic astrocytomas, and 53 had glioblastomas multiforme (GM). At the DMBT1 locus, LOH was observed very frequently in all three histological groups, with no significant difference in the frequency of LOH among the three histological groups. At the MMAC/PTEN locus, patients with GM exhibited a significantly increased frequency of LOH (72%) compared with patients with anaplastic astrocytomas (29%) or anaplastic oligodendrogliomas (31%) (P < 0.0001). Kaplan-Meier survival plots showed that patients with LOH at the MMAC/PTEN locus had a significantly worse prognosis than did patients without LOH at the MMAC/PTEN locus [hazard ratio (LOH versus non-LOH), 2.65; 95% confidence interval (CI), 1.69-4.46; P < 0.0001]. Cox proportional hazards regression analysis, adjusted for age at surgery and histological grades (GM and non-GM), showed that LOH at the MMAC/PTEN locus was a significant predictor of shorter survival [hazard ratio (LOH versus non-LOH), 2.01; 95% CI, 1.1-3.5; P = 0.018). Our analysis failed to indicate a similar association between the frequency of LOH at the DMBT1 locus and patient survival [hazard ratio (LOH versus non-LOH), 2; 95% CI, 0.37-3.13; P = 0.2]. These results suggest that the DMBT1 gene may be involved early in the oncogenesis of gliomas, whereas alterations in the MMAC/PTEN gene may be a late event in the oncogenesis related to progression of gliomas and provide a significant prognostic marker for patient survival.

Agglutinins↗
PubMed1997

Summary measures of the insulin resistance syndrome are adverse among Mexican-American versus non-Hispanic white children: the Corpus Christi Child Heart Study.

BACKGROUND: Mexican-American (MA) adults are known to have a greater burden of diabetes and insulin resistance than non-Hispanic white (NHW) people. In this report, we examined data obtained from MA and NHW third-grade children for evidence of a pattern consistent with the insulin resistance syndrome. In addition, we developed two summary measures characterizing insulin resistance syndrome to compare measures of this syndrome among our population. METHODS AND RESULTS: Data regarding fasting insulin, triglycerides, HDL cholesterol, systolic blood pressure, and body mass index (BMI) were available for 403 third-grade children. Median levels of insulin and glucose were significantly higher in MA boys and girls than in NHW boys and girls. Risk factors characterizing insulin resistance, including levels of insulin, triglycerides, systolic blood pressure, HDL cholesterol, and BMI were categorized as above or below the total population median. MA children were more likely than NHW children to have three or more adverse risk factors (55% versus 37%). When risk factors were converted to Z scores, and the five Z scores were summed for each individual, MA boys and girls had higher mean scores than NHW boys and girls (means for boys, 0.65 versus -0.97, P<.0001; girls, 0.52 versus -0.30, P<.04). Principal components analysis was used to create a summary score or index representing the insulin resistance syndrome. This summary score was significantly higher among MA boys and girls than NHW boys and girls (means for boys, 0.34 versus -0.72, P<.0001; girls, 0.35 versus -0.04, P=.056). CONCLUSIONS: Our results support the hypothesis that MA children exhibit a greater degree of the insulin resistance syndrome than NHW children, especially among boys. We conclude that some of the factors responsible for the increased risk of NIDDM seen among MA adults are demonstrable in childhood.

Blood Pressure↗
PubMed1997

Greater incidence of hospitalized myocardial infarction among Mexican Americans than non-Hispanic whites. The Corpus Christi Heart Project, 1988-1992.

BACKGROUND: Since Mexican Americans have adverse patterns of risk factors for myocardial infarction relative to non-Hispanic whites, the incidence of myocardial infarction should be greater among Mexican Americans than among non-Hispanic whites. This expectation conflicts with reports generated from death certificate registries. METHODS AND RESULTS: Data regarding myocardial infarction attacks and incident events were collected for a 4-year period in the Corpus Christi Heart Project, a population-based surveillance project for hospitalized coronary heart disease events. For both women and men, Mexican Americans experienced greater hospitalization rates for both attacks and incident events than non-Hispanic whites. Age-adjusted attack rate ratios comparing Mexican Americans with non-Hispanic whites were 1.59 (95% CI, 1.05 to 2.41) and 1.31 (95% CI, 1.18 to 1.45) among women and men, respectively. Corresponding incidence ratios were 1.52 (95% CI, 1.28 to 1.80) and 1.25 (95% CI, 1.10 to 1.42). CONCLUSIONS: This is the first report documenting greater incidence of hospitalized myocardial infarction among Mexican Americans than among non-Hispanic whites, a biologically plausible finding given the risk factor patterns observed in the Mexican-American population. Public health planners and clinicians should be aware of the importance of myocardial infarction as a health problem in the Mexican-American population. Culturally appropriate prevention strategies should be developed for and tested in Mexican-American populations.

Adult↗
PubMed1997

Sodium chloride increases the ciliary transportability of cystic fibrosis and bronchiectasis sputum on the mucus-depleted bovine trachea.

Mucus retention in the lungs is an important feature of several respiratory diseases (Regnis, J.A., M. Robinson, D.L. Bailey, P. Cook, P. Hooper, H.K. Chan, I. Gonda, G. Bautovich, and P.T.P. Bye. 1994. Am. J. Respir. Crit. Care Med. 150:66-71 and Currie, D.C., D. Pavia, J.E. Agnew, M.T. Lopez-Vidriero, P.D. Diamond, P.J. Cole, and S.W. Clarke. 1987. Thorax. 42:126-130). On the mucus-depleted bovine trachea, the ciliary transport rate of sputum from patients with cystic fibrosis and bronchiectasis of other causes was slow, but the rate was doubled by increasing the sodium chloride content by 90 mM. Increasing the sputum osmolality by inspissation or by the addition of nonelectrolytes had a similar effect. The viscoelasticity of sputum, but not the bovine ciliary beat frequency, was markedly saline dependent over the pathophysiological range. This suggests that low mucus salinity, not (as is generally assumed) its under-hydration, contributes to its retention in bronchiectasis due to cystic fibrosis and other causes, probably by affecting its rheology. It also indicates how the genetic defect in cystic fibrosis might lead to impaired mucus clearance. Therapies that increase the osmolality of lung mucus might benefit patients with mucus retention.

Animals↗