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Biomedical subjects

W W Lee

Publications and source records attributed to W W Lee.

At least 19 recordsLinked to original sources
PubMed1999

Relation of salivary cotinine to blood pressure in middle-aged cigarette smokers.

BACKGROUND: In laboratory research, nicotine administration is associated with increases in blood pressure. In epidemiologic research, however, the amount of reported cigarette smoking has no consistent relation with blood pressure. The objective of this study was to examine the relation of a nicotine metabolite (salivary cotinine) to systolic and diastolic blood pressure in current smokers being screened for entry to a clinical trial. METHODS AND RESULTS: Data were obtained from 5164 middle-aged cigarette smokers during screening for the Lung Health Study. Multiple linear regression was used to examine the association of salivary cotinine and number of cigarettes smoked per day to systolic and diastolic blood pressure with age, body mass, years of education, alcohol intake, and recent caffeinated beverage use controlled in all analyses. Although smoking frequency was unrelated to blood pressure, salivary cotinine was related to greater systolic blood pressure in both men and women and greater diastolic blood pressure in men. CONCLUSIONS: The association between salivary cotinine and blood pressure in these analyses suggests that long-term nicotine exposure may be related to modest elevations in blood pressure in cigarette smokers.

Biomarkers↗
PubMed1998

Early and late weight gain following smoking cessation in the Lung Health Study.

The authors examine weight gains associated with smoking cessation in the Lung Health Study (1986-1994) over a 5-year follow-up period. A cohort of 5,887 male and female smokers in the United States and Canada, aged 35-60 years, were randomized to either smoking intervention or usual care. Among participants who achieved sustained quitting for 5 years, women gained a mean of 5.2 (standard error, 5.0) kg in year 1 and a mean of 3.4 (standard error, 5.5) kg in years 1-5. Men gained a mean of 4.9 (standard error, 4.9) kg in year 1 and a mean of 2.6 (standard error, 5.8) kg in years 1-5. In regression analyses, smoking-change variables were the most potent predictors of weight change. Participants going from smoking to quit-smoking in a given year had mean weight gains of 2.95 kg/year (3.61%) in men and 3.09 kg/year (4.69%) in women. Over 5 years, 33% of sustained quitters gained > or = 10 kg compared with 6% of continuing smokers. Also among sustained quitters, 7.6% of men and 19.1% of women gained > or = 20% of baseline weight; 60% of the gain occurred in year 1, although significant weight gains continued through year 5. The average gains and the high proportions of sustained and intermittent quitters who gained excessive weight suggest the need for more effective early interventions that address both smoking cessation and weight control.

Adult↗
PubMed1998

Neuroanatomical correlates to central deafness.

Our research experience with five centrally deaf patients showed that damage to various anatomical sites could result in central deafness. This finding was contrary to the commonly held notion that both Heschl's gyri must be severely damaged to yield central deafness. To discover whether lesions in various brain areas could cause central deafness, we reviewed 33 cases of central deafness reported in the literature which had sufficient radiological data to determine the anatomical regions involved. Both Heschl's gyri were involved in the majority of these cases, but there were definite exceptions. In these exceptional cases of central deafness, subcortical areas were involved (usually the internal capsule), as was the insula. Overall findings are discussed and recommendations are offered for the future study of centrally deaf patients.

Adult↗
PubMed1998

The incidence of IDDM in Singapore children.

OBJECTIVE: To determine the incidence of insulin dependent diabetes mellitus (IDDM) in children 0-12 years of age in Singapore, which has a population of 2.9 million. METHODS: The primary source was a 2-year phone and mail survey of doctors in the government and government restructured hospitals and the private sector. The secondary source was the membership records of the Diabetes Society of Singapore. RESULTS: Using the capture-recapture method, ascertainment was assessed to be 92.2% complete. The age standardised incidence rate was 2.46 per 100,000 children 0-12 years old, for the period 1992-1994 (95% confidence interval: 2.16-2.75). The data seemed to indicate a rising incidence of IDDM in this population, being 1.4/100,000 in 1992, 2.4/100,000 in 1993 and 3.8/100,000 in 1994. The male: female ratio is 1:1.85. There was seasonal variation with fewer cases from July to October and more from November to May. Five percent of patients had a first degree relative with IDDM. Malays appeared to have a lower incidence (1.23/100,000) compared to the Chinese (2.25/100,000) and the Indians (5.78/100,000). CONCLUSIONS: The incidence of IDDM in Singapore children is similar to that reported for Hong Kong and Japan, but higher than that for Shanghai. The female preponderance is similar to that seen in other Asian population. The data suggests a rising incidence of IDDM in Singapore and differences in incidence between the Malays, Chinese and Indians, but further observations are needed.

Child↗
PubMed1997

Olfactory dysfunction in patients with head trauma.

BACKGROUND: The ability to smell is commonly altered by head trauma (HT). However, the nature, prevalence, prognosis, and etiology of such alterations are poorly understood. OBJECTIVES: To quantitatively determine the degree of olfactory function in patients with HT-related chemosensory complaints and to examine the influences of age, sex, HT severity, time since HT, and other variables on such function. Also, to use quantitative magnetic resonance imaging (MRI) to establish whether and to what degree damage to the olfactory bulbs and tracts, frontal lobes, and temporal lobes occurs. PATIENTS AND METHODS: Two hundred sixty-eight patients with HT from the University of Pennsylvania Smell and Taste Center, Philadelphia, were administered a quantitative odor identification test, a depression inventory, and a medical history questionnaire; 66 were retested after individual test-retest periods ranging from 1 month to 13 years. The volume of olfactory-related brain structures was determined in 15 patients and 15 controls using MRI. RESULTS: One hundred seventy-nine patients (66.8%) had anosmia, 55 (20.5%) had microsmia, and 34 (12.7%) had normosmia. Frontal impacts produced less dysfunction than back or side impacts. Of the 66 retested patients, 24 (36%) improved slightly, 30 (45%) had no change, and 12 (18%) worsened; only 3 patients, none of whom initially had anosmia, regained normal olfactory function. Trauma severity was related to olfactory test scores in patients with microsmia. Parosmia prevalence decreased from 41.1% to 15.4% over an 8-year posttrauma period. Olfactory bulb and tract volumes of male, but not female, patients with HT were greatly reduced relative to volumes of controls. CONCLUSIONS: Patients complaining of HT-related olfactory dysfunction typically have anosmia and rarely regain normal olfactory ability, parosmia prevalence decreases over time in such patients, and damage to olfaction-related brain structures can be observed in most such patients using an appropriate MRI protocol.

Adult↗
PubMed1997

Conventional and maximum length sequences middle latency response in patients with central nervous system lesions.

Conventional and maximum length sequence (MLS) middle latency response (MLR) procedures were compared across several parameters for control patients and patients with central nervous system lesions. There were similar findings for both populations and both types of MLR for the absolute latencies of Na and Pa waves. Middle latency waves were absent more often in the neurologic than control subjects for both the conventional and MLS-MLR procedures. Overall, more MLR waves were present for the MLS technique than for the conventional MLR technique. Differences in wave amplitude were significant for several recording sites when comparing neurologic with control groups, but findings were similar for wave amplitude when comparing the two types of MLR procedures for the neurologic population. Based on these findings, no clear diagnostic advantage was shown for using the MLS-MLR technique. These findings are further discussed.

Adolescent↗
PubMed1996

Development of the 12-item Cross-Cultural Smell Identification Test (CC-SIT).

The development of the 12-item Cross-Cultural Smell Identification Test (CC-SIT), based upon items from the University of Pennsylvania Smell Identification Test (UPSIT), is described. In developing this test, the authors initially selected UPSIT items that are familiar to most persons from North American, European, South American, and Asian cultures. The CC-SIT was then administered to 198 people ranging in age from 5 to 96 years, and the the test scores were compared to analogous items from UPSITs administered to 198 age-, sex-, race-, and smoking-habit-matched control subjects. Since the pattern of test scores did not differ for the two groups, the authors developed normative data for the 12-item test using equivalent UPSIT items sampled from a database containing UPSIT scores for 3760 subjects. Norms are provided for determining the percentile ranks of a given patient's score as a function of age and gender. The CC-SIT provides, for the first time, a self-administered means for reliably assessing olfactory function in less than 5 minutes.

Adolescent↗
PubMed1996

Methacholine reactivity predicts changes in lung function over time in smokers with early chronic obstructive pulmonary disease. The Lung Health Study Research Group.

As part of a clinical trial of early intervention in chronic obstructive pulmonary disease (COPD) (the Lung Health Study), 5,733 smokers with mild to moderate airflow obstruction underwent methacholine challenge tests at baseline. All participants were randomized to receive either usual care (no intervention) or special intervention, consisting of intensive smoking cessation counseling and the prescription of a metered-dose inhaler containing either ipratropium bromide or placebo (two inhalations three times daily). For this report, we analyzed the relationship between baseline methacholine reactivity and subsequent change in lung function. Methacholine reactivity was expressed as a logarithmic function of the two-point slope of percent decline in FEV1 over the concentration of methacholine (LMCR). Using a random effects linear model, LMCR was found to be a strong predictor of change in FEV1% predicted, after controlling for baseline lung function, age, sex, baseline smoking history, and changes in smoking status. Significant interactions were found between reactivity and smoking behavior. In the first year, participants who quit smoking showed improvement in FEV1, whereas continuing smokers showed worsening, and between Years 1 and 5, lung function declined to a greater extent in continuing smokers than in sustained quitters. For both time periods, these quitter/smoker differences increased as a function of airway reactivity. These findings indicate that methacholine reactivity is an important predictor of progression of airway obstruction in continuing smokers with early COPD, independent of the baseline level of obstruct.

Bronchoconstrictor Agents↗
PubMed1996

A recent case of congenital malaria in Singapore.

We report a case of congenital malaria in a 2-month-old baby girl, born in Singapore of a Singaporean mother, who presented with fever for one week, gross hepatosplenomegaly and anaemia (haemoglobin 5.6 g/dL) and thrombocytopenia. Peripheral blood films showed Plasmodium vivax. There was no local transmission at that time, but the mother had spent the first 6 months of her pregnancy in Pakistan, where she had been treated for prolonged fever at 4 months amenorrhoea with ibuprofen alone. The mother and 2 siblings were asymptomatic and repeatedly tested negative on blood films for malaria parasites, but the mother tested positive for antibodies to Plasmodium on the Fluorescent Antibody Test. The child was treated with oral chloroquine and made an uneventful recovery. We postulate that this is believed to be the first recent case of congenital malaria in Singapore since it was declared malaria free in 1982. The diagnosis should be considered in babies of mothers who have travelled to places where malaria is endemic, as maternal infection may be unrecognised, and the child may be asymptomatic at birth.

Antimalarials↗
PubMed1995

A study of the test-retest reliability of ten olfactory tests.

Ten tests of olfactory function (including tests of odor identification, detection, discrimination, memory, and suprathreshold odor intensity and pleasantness perception) were administered on two test occasions to 57 subjects ranging in age from 18 to 83 years. The stability of the average test scores was determined across the two test sessions for 14 measures derived from these 10 tests and for subcomponents of the Japanese T&T olfactometer threshold test. In addition, the test-retest reliability (Pearson r) of each test measure was established. With the exception of a response bias measure, the average test scores did not differ significantly across the two test sessions. Statistically, the reliability coefficients of the primary test measures fell into three general classes bound by the following r values: 0.43-0.53; 0.67-0.71; 0.76-0.90. Detection threshold values were more reliable than recognition threshold values; those based upon a single ascending presentation series were much less reliable than those based upon a staircase procedure. The relationship between test length and reliability was examined for several of the tests and mathematically modeled. For example, within the staircase series incorporating the odorant phenyl ethyl alcohol, reliability was related (R2 = 0.984) to the number of reversals included in the threshold estimate by a function derived from the Spearman-Brown formula; namely, reliability = 0.455* # reversals/[1 + 0.455 (# reversals - 1)]. Reversal location, per se, had little influence on reliability. Overall, this study suggests that (i) considerable variation is present in the reliability of olfactory tests, (ii) reliability is a function of test length, and (iii) caution is warranted in comparing results from nominally different olfactory tests in applied settings since the findings may, in some instances, simply reflect the differential reliability of the tests.

Adolescent↗
PubMed1995

The auditory brain stem response in patients with brain stem or cochlear pathology.

OBJECTIVE: The purpose of this study was to determine the value, based on true-positive and false-positive rates, of various auditory brain stem response (ABR) indices in discriminating patients with brain stem lesions from patients with cochlear lesions. DESIGN: A factorial design was used in this retrospective study. Receiver operating characteristics (ROC) curves were constructed to analyze the performance of 32 patients with brain stem lesions and 33 patients with cochlear involvement for the absolute latency of wave V; the I-III, III-V, and I-V interwave intervals; the interaural latency difference and the V/I amplitude ratio. Analyzed in the same manner were four combinations of ABR indices. RESULTS: Based on the ROC curves, the clinically most valuable index was the I-V interval, but overall the individual indices showed only moderate sensitivity to brain stem pathology. By combining several indices, the sensitivity to brain stem involvement was improved. However, as expected, the overall false-positive rate also increased. CONCLUSIONS: There is a diagnostic advantage to using more than one ABR index in evaluating patients suspected of having brain stem involvement.

Adolescent↗
PubMed1995

Spirometry in the Lung Health Study: II. Determinants of short-term intraindividual variability.

The Lung Health Study (LHS) is a randomized clinical trial designed to determine whether a smoking intervention program and use of an inhaled bronchodilator (BD) can reduce the rate of decline of FEV1 in cigarette smokers with airflow limitation. During recruitment, spirometry was performed at second and third screening visits, a mean of 21 d apart. A total of 5,887 smokers, 35 to 60 yr of age and of whom 63% were men, met the study eligibility requirements. Smokers taking physician-prescribed BDs or with an FEV1 < 50% or > 90% predicted were excluded, as were those whose FEV1/FVC ratio was greater than 70%. Two inhalations of isoproterenol were given to determine BD response during the second visit. A serial dilution methacholine challenge test was done during the third visit to determine nonspecific airway reactivity. Ninety-five percent of the differences between FEV1 measured at the two visits were within 240 ml for women and within 320 ml for men (coefficients of repeatability). The best independent predictors of the mean short-term (between visit) intraindividual FEV1 variability were factors indicating intrinsic airway reactivity of the participants: bronchodilator response, methacholine reactivity, and the presence of wheezing; as well as factors influenced by the quality of spirometry testing: the difference between the highest and second highest FEV1s and peak flows during baseline spirometry, and the time to reach peak flow (PEFT).

Adult↗
PubMed1994

Gender difference in airway hyperresponsiveness in smokers with mild COPD. The Lung Health Study.

Methacholine bronchoprovocation challenge testing was successfully completed in 5,662 participants (3,556 men and 2,106 women) at the time they were randomized into the Lung Health Study, a multicenter trial designed to evaluate early intervention in chronic obstructive pulmonary disease (COPD). All participants were smokers between the ages of 35 and 60 yr who had mild COPD. The male:female prevalence of a positive challenge (PC20FEV1) was 25%:48% and 63%:87% at a PC20FEV1 of < or = 5 mg/ml (AHR5) and < or = 25 mg/ml (AHR25), respectively. This analysis explores these marked gender differences in airway hyperresponsiveness (AHR). Relative risks (RR) for predictors of AHR and the 95% confidence intervals (95% CI) were estimated using semiparametric Cox proportional-hazards models. The initial model controlled for age, gender, smoking history, height, and weight. The RR (95% CI) for female gender was 1.75 (1.60, 1.92). When the measured baseline FEV1 was added to the model as a surrogate for airway caliber, the RR for female gender decreased to 1.06 (0.96, 1.18). Thus, in this population of middle-aged smokers with mild COPD, the high prevalence of AHR appears to be associated with a decrease in airway caliber. The higher prevalence of AHR noted in women is due to their having a smaller airway caliber than their male counterparts.

Adult↗
PubMed1994

Categorization response time with multidimensional stimuli.

Categorization response time (RT) was examined in three separate experiments, in each of which exemplars varied on two physical dimensions. Three different types of stimuli were used: (1) horizontal and vertical line segments of varying length that were joined at an upper left corner, (2) rectangles of varying width and height, and (3) circles or semicircles of varying size with a radial arm of varying orientation. No evidence was found that stimulus familiarity or the category prototypes played any special role in determining categorization RT. Instead, RT decreased with distance from the stimulus to the categorization decision bound.

Decision Making↗
PubMed1992

The lung health study: airway responsiveness to inhaled methacholine in smokers with mild to moderate airflow limitation. The Lung Health Study Research Group.

As part of a multicenter clinical trial (Lung Health Study), methacholine inhalation challenge testing was performed in 5,877 current cigarette smokers, ages 35 to 59 yr (mean 48.5 +/- 6.8 yr), with borderline to moderate airflow limitation (FEV1/FVC ratio 63.0 +/- 5.5). The test was successfully completed in 96.4% of subjects, of whom 63% were male and 95.9% were white. Symptomatic reactions to methacholine were rarely severe enough to require evaluation by a trial physician. Nonspecific airways hyperresponsiveness (AHR) was defined as a greater than or equal to 20% decline in FEV1 from the post-diluent control value after inhalation of less than or equal to 25 mg/ml methacholine. AHR was noted in a significantly higher percentage of women (85.1%) than men (58.9%). Moreover, nearly twice as many women as men (46.6 and 23.9%, respectively) responded to less than or equal to 5 mg/ml of methacholine. In both men and women, baseline degree of airways obstruction and clinical center were strongly associated with AHR (p less than 0.001), whereas age was not. Additional associations with AHR were analyzed in men and women separately using logistic regression after adjustment for baseline lung function, age, and center-to-center differences. In men, AHR was significantly related to symptoms of wheeze, chronic cough and/or sputum, and a history of asthma or hay fever (p less than 0.004), but not to current or lifetime tobacco use. By contrast, among women, AHR was not significantly associated with chronic cough and/or phlegm (p greater than 0.05) or a past history of asthma or hay fever (p greater than 0.1) and was only weakly related to wheeze and current asthma (p = 0.04), as well as to cigarette pack-years (p = 0.044). These results indicate that most continuing smokers with functional evidence of early chronic obstructive pulmonary disease have nonspecific AHR that is strongly related to gender and baseline lung function and, to a lesser extent, to respiratory symptoms. The reason for the striking effect of gender on AHR in early chronic obstructive pulmonary disease is unclear but cannot be attributed to male-female differences in age, cigarette use, presence of asthma, or baseline degree of airflow obstruction.

Adult↗
PubMed1992

Enterogenous cyst of the fourth ventricle: case report.

The authors present an intracranial enterogenous cyst of the fourth ventricle in a Chinese woman having symptoms of headache, dizziness and vertigo for approximately six months. A computerized tomography study of the brain disclosed a low density lesion within the fourth ventricle. A cystic tumor was completely removed and a histopathological examination diagnosed it is an enterogenous cyst; a rare lesion. During the post-operative follow-up, her symptoms gradually resolved and she was free of complaints within two years.

Brain Diseases↗
PubMed1991

Predicting similarity and categorization from identification.

In this article, the relation between the identification, similarity judgment, and categorization of multidimensional perceptual stimuli is studied. The theoretical analysis focused on general recognition theory (GRT), which is a multidimensional generalization of signal detection theory. In one application, 2 Ss first identified a set of confusable stimuli and then made judgments of their pairwise similarity. The second application was to Nosofsky's (1985b, 1986) identification-categorization experiment. In both applications, a GRT model accounted for the identification data better than Luce's (1963) biased-choice model. The identification results were then used to predict performance in the similarity judgment and categorization conditions. The GRT identification model accurately predicted the similarity judgments under the assumption that Ss allocated attention to the 2 stimulus dimensions differently in the 2 tasks. The categorization data were predicted successfully without appealing to the notion of selective attention. Instead, a simpler GRT model that emphasized the different decision rules used in identification and categorization was adequate.

Adult↗