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Biomedical subjects

W W Wong

Publications and source records attributed to W W Wong.

At least 19 recordsLinked to original sources
PubMed1995

Energy requirements from infancy to adulthood.

To investigate how age and body composition affect energy requirements, the sedentary daily expenditure (SDE) and basal metabolic rate (BMR) of 101 infants, 82 girls, and 27 adults were measured. Energy expenditure was scaled for differences in body size to test the effects of age and body fatness. A power function was superior to linear models. For all subjects, WT0.63 (where WT is weight) or FFM0.63 (where FFM is fat-free mass) explained 94% of the variability in BMR, and WT0.70 or FFM0.70 explained 97% of the variability in SDE. The effects of height and fat mass (kg or % body wt) on BMR and SDE scaled for weight or fat-free mass were age dependent. Best-fitted exponents relating BMR or SDE to body size differed between children (0.40-0.52) and infants (1.04-1.30) (P = 0.001). Human energy requirements from infancy to adulthood appear to be a power, not a linear, function of body weight and composition.

Adolescent↗
PubMed1995

Cholesterol synthesis and absorption by 2H2O and 18O-cholesterol and hypocholesterolemic effect of soy protein.

The kinetic behavior of orally ingested 18O-cholesterol was compared with that of orally ingested 13C5-cholesterol in two normocholesterolemic men and the hypocholesterolemic effect of soy protein was demonstrated in 12 hypercholesterolemic men. Our results indicated no difference in the metabolism of orally ingested 18O- and 13C5-cholesterol. The use of 18O-cholesterol and 13C5-cholesterol also allowed simultaneous estimation of fractional rates of cholesterol synthesis using the 2H2O method, which were calculated to be 5.76 and 8.17%/d for the two normocholesterolemic subjects. The percent reduction in plasma cholesterol levels were found to be greater when the hypercholesterolemic men were placed on a soy protein diet than on an animal protein diet.

Absorption↗
PubMed1995

Estimating body composition in late gestation: a new hydration constant for body density and total body water.

Twenty women underwent body density (DB) measurements using underwater weighing with correction of residual lung volume by nitrogen dilution and total body water (TBW) using isotope dilution of 18O to estimate body composition at 30 wk of gestation. DB and TBW were used as independent variables in the same equation. The hydration constant (HC) of fat-free mass (FFM) was estimated as 0.762; based on this HC, new body composition equations for both DB and TBW were derived. These equations were prospectively tested in an additional 20 women at 30 wk of gestation. No significant differences were detected between estimates of percent body fat (%F) using either the newly derived DB or TBW equations and estimates of %F using both DB and TBW. Ten of these forty women were evaluated postpartum. There was no significant difference in %F estimated by either TBW or DB compared with standard equations (hydration of FFM = 0.72) and %F using both DB and TBW. These results highlight the importance of either measuring both DB and TBW or using an appropriate hydration constant for FFM in estimating body composition during pregnancy or conditions associated with increased body water.

Adult↗
PubMed1995

Fluid changes during pregnancy: use of bioimpedance spectroscopy.

The increase in body water during pregnancy is responsible for the largest portion of weight gain and is of interest of clinical practitioners. However, assessing changes in body fluids is not easily accomplished during pregnancy. The purpose of this study was to examine the accuracy of bioelectrical impedance spectroscopy for estimating fluid volumes before, during, and after pregnancy. Ten healthy adult women were recruited for the study. Total body water (TBW) and extracellular fluid (ECF) volume were measured at baseline (preconception); 8-10, 24-26, and 34-36 wk of gestation; and 4-6 wk postpartum by deuterium oxide and NaBr dilution, respectively. Estimates of TBW and ECF were also obtained by bioimpedance spectroscopy (BIS). At baseline, mean values for dilution and BIS estimates of TBW and ECF were 33.2 +/- 4.6 (SD) vs. 31.6 +/- 6.2 liters and 15.2 +/- 1.3 vs. 16.9 +/- 2.3 liters, respectively. TBW and ECF estimated by BIS were not significantly different from the dilution values at any time point. These results suggest that BIS may be useful in estimating volumes of ECF and TBW during pregnancy.

Adult↗
PubMed1995

Influence of early feeding mode on body composition of infants.

To determine the effect of infant feeding mode on body composition, a cross-sectional study was designed in which 10 breast-fed and 10 formula-fed infants were studied at 1 month of age, and another 10 breast-fed and 10 formula-fed infants at 4 months of age. Anthropometric measurements included body weights, lengths, selected diameters, circumferences and skinfold thicknesses. Total body water (TBWO) was measured by 18O dilution. A dose equivalent to 300 mg 18O/kg body weight was administered orally to the infants. Fat-free mass (FFMO) was calculated from TBWO using reference hydration constants of 0.805 and 0.798 at 1 and 4 months, respectively. Body fatO was taken as the difference between weight and FFMO. Total-body electrical conductivity (TOBEC) measurements were used to estimate FFMT and FATT. ANOVA was used to analyze the anthropometric and body composition data using feeding mode and age as grouping factors. Anthropometric measurements did not differ by feeding mode. TBW (kg) and FFM (kg) and body fat (kg) derived from 18O dilution or TOBEC did not differ by feeding mode. TBWO,T (%wt), FFMO,T (%wt), and body fatO,T (%wt) derived from 18O dilution and TOBEC differed significantly between the breast-fed and formula-fed infants at 4 months of age (p < 0.05). Expressed as a percentage of body weight, TBWO and FFMO,T were higher and body fatO,T was lower among the 4-month formula-fed infants.

Adipose Tissue↗
PubMed1994

Radiotherapy for isolated increases in serum prostate-specific antigen levels after radical prostatectomy.

OBJECTIVE: To assess the outcome of radiotherapy in patients with increased serum prostate-specific antigen (PSA) levels 6 months or more after radical prostatectomy. DESIGN: In 27 Mayo Clinic patients, we examined the results of radiotherapy relative to various potentially prognostic factors during a median follow-up of 25 months. MATERIAL AND METHODS: All 27 patients had no nodal involvement at the time of prostatectomy and no clinical evidence of disease, as determined by history, physical examination, a radionuclide bone scan, computed tomography of the abdomen and pelvis, chest roentgenography, complete blood cell counts, and serum chemistry profiles. With use of 10-MV photons and a four-field approach, these patients received irradiation to the prostatic bed (60 to 67 Gy in 1.8- to 2.0-Gy fractions). RESULTS: Levels of PSA initially decreased in 24 of the 27 patients (89%). In 16 of the 27 patients (59%), the PSA level decreased to 0.3 ng/mL or less without hormonal intervention. "Freedom from failure" (defined as the actuarial chance of maintaining a PSA level of 0.3 ng/mL or less) was 58% at 2 years and 48% at 3 years. The response to salvage radiotherapy was more favorable in patients with no tumor spread into the seminal vesicles and those with serum PSA levels of less than 1.1 ng/mL at the beginning of radiotherapy than in those with seminal vesicle involvement or higher PSA levels. In addition, patients who received radiation doses of 64 Gy or more had more favorable responses than did those who received lesser doses. Radiotherapy resulted in no severe toxicity. No patient had clinical evidence of disease at the time of this report. CONCLUSION: Isolated increases in serum PSA after prostatectomy indicate the presence of residual or recurrent disease, and radiotherapy effectively decreases the PSA in approximately half the cases. This result is achieved by eradicating residual or recurrent cancer in the postoperative tumor bed.

Aged↗
PubMed1994

Liposarcoma of the pleura.

Pleural liposarcomas are extremely rare; only eight cases have been reported in the literature. Herein we describe a 38-year-old man who had dyspnea on exertion and chest pain. Computed tomography of the chest revealed a large mass in the right pleural cavity. Thoracotomy was performed, and the patient recovered with no complications. Postoperative adjuvant irradiation was successful. In addition to the current case, we review the previously reported cases of pleural liposarcomas and discuss the treatment outcomes.

Adult↗
PubMed1994

Energy expenditure of female adolescents.

OBJECTIVE: Because of the difficulty in obtaining accurate dietary intake information on children and adolescents, the World Health Organization (WHO) has recommended that energy requirements in children and adolescents are best established by estimate of energy expenditure in free-living individuals. To define the energy requirements of healthy female adolescents, we used the doubly labeled water method to estimate the total energy expenditure (TEE) of nine female Caucasian adolescents (mean age +/- SD 13.2 +/- 1.8 years; range 10.3-16 years). METHODS: We collected a baseline plasma and saliva sample from each subject after she received by mouth 125 mg of 18O and 100 mg of 2H2O/kg body weight. A 3-hour postdose plasma sample was also collected. Subsequently at home, each subject collected one postdose saliva sample daily for the next 10 days. The 24-hour respiratory quotient (RQ) of each subject was measured by whole-room calorimetry. The 18O and 2H abundances of the plasma and saliva samples were measured by gas-isotope-ratio mass spectrometry. Isotope dilution spaces of 18O (No) and 2H (NH) were calculated from the enrichment levels of these isotopes in the 3-hour postdose plasma sample. The fractional turnover rates of 18O (ko) and 2H (kH) were calculated from the monoexponential decay curves of these isotopes in the saliva samples. The average CO2 production rate (rCO2) over the 10-day period was calculated as rCO2 (mol/day) = 0.4584 x (ko x No-kH x NH). The average TEE was calculated from the rCO2 using the Weir equation. RESULTS: TEE calculated by the isotope method was 2322 +/- 281 kcal/day (range 1850-2656 kcal/day), which is higher than the levels of energy expenditure (1910-2140 kcal/day) reported by the WHO for healthy female teenagers with a desirable body composition and appropriate level of physical activity. CONCLUSION: Our results suggest that the activity factors used by the WHO in the calculation of energy expenditure of female adolescents between 10 and 16 years of age might have been underestimated.

Adolescent↗
PubMed1994

A cross-sectional seroepidemiologic survey of chronic hepatitis B virus infections in Southeast Asian immigrants residing in a Canadian urban centre.

To document the number of individuals who might qualify for interferon therapy and what impact the costs of treatment will have on the health care system, the serologic and biochemical profiles of 140 hepatitis B surface antigen (HBsAg) positive individuals of Asian descent (72 Vietnamese, 69 Chinese) were evaluated with respect to their hepatitis B e antigen (HBeAg) status and biochemical parameters (ALT, bilirubin, and prothrombin time). The mean +/- SD age of the study population was 33.5 +/- 13.4 y. Eighty-six (61%) were male. The HBeAg was positive in 64 (46%) of cases (41% of Vietnamese and 51% of Chinese) with no apparent sexual predilection. The ALT values exceeded 1.5 x normal in 23/64 (36%) cases. Mean serum bilirubin and prothrombin times were within normal limits. The results of this study demonstrate that approximately 50% of HBsAg positive immigrants from Southeast Asia are also HBeAg positive, and 36% of these individuals have elevated ALT values (> 1.5 x normal). Thus, according to estimated carrier rates and present guidelines for treatment, approximately 1-2% of the total Southeast Asian immigrant population are candidates for interferon therapy. With an immigrant population of approximately 900,000 and a cost of $6,500/patient, the total cost to the Canadian health care system will approach $100 million, or 1.3% of the present health care budget. These results underscore the need for a reappraisal of present treatment guidelines and implementation of universal vaccination in this country.

Adolescent↗
PubMed1994

Caltrac versus calorimeter determination of 24-h energy expenditure in female children and adolescents.

The purpose of this study was to determine the validity of the Caltrac accelerometer for estimating 24-h energy expenditure (EE) in children and adolescents. EE for 40 girls (13.0 +/- 1.8 yr) was assessed for 24 h via indirect calorimetry in whole-room calorimeters. EE and activity level were estimated concurrently by two Caltrac accelerometers placed on the subjects at each hip. Significant correlations (P < 0.001) resulted between Caltrac estimates and calorimeter values for 24-h total EE (TEE, r = 0.80), sedentary daily EE (SDEE, r = 0.84), and waking EE (WEE, r = 0.85). Nonetheless, the Caltrac significantly (P < 0.001) underestimated EE in all experimental conditions (TEE: -13.3 +/- 8.6%; SDEE: -6.8 +/- 7.3%; WEE: -30.4 +/- 8.5%). A significant multiple correlation between calorimeter values and a combination of Caltrac activity counts and body weight (R = 0.86, P < 0.001) suggested these variables could be useful for daily EE estimation. Additional analyses indicated that as EE increased, the absolute difference between Caltrac and calorimeter values also increased. The significant correlations between Caltrac and calorimeter values suggest the Caltrac may be useful for assessing daily caloric expenditure for groups of children.

Acceleration↗
PubMed1993

Successful treatment of Kaposi's sarcoma with interferon-alpha in a patient with acquired immunodeficiency syndrome.

Although combined therapy with interferon-alpha and zidovudine may be safely administered to some patients with the acquired immunodeficiency syndrome (AIDS) and Kaposi sarcoma, no ethnic Chinese patient has been successfully treated before in this area. This case report concerns a 47-year-old male with a history of bisexuality who had suffered from oral ulcers for half a year, Human immunodeficiency virus (HIV) serology was positive, and pathology of the oral ulcers disclosed Kaposi sarcoma. Combination therapy with zidovudine and interferon-alpha was initiated. The patient received a low-dose regimen of 5.0 million U interferon-alpha s.c. per day for 8 weeks and 5 million U twice a week for another 8 weeks. The oral ulcers faded away without recurrence. This report also reviews the literatures on treatment of AIDS-related Kaposi sarcoma with interferon.

Acquired Immunodeficiency Syndrome↗
PubMed1992

Prognostic indicators in node-negative early stage breast cancer.

With the increasing availability of screening mammography, more women are diagnosed as having breast cancers at an early, node-negative stage. The majority of these patients would be cured with total mastectomy or breast conservation treatment. However, about 30% of the patients would have recurrence of disease in distant sites. In recent randomized clinical trials, adjuvant systemic therapy has been shown to reduce the rate of recurrence in these patients. Proper selection of patients for adjuvant therapy is necessary to avoid exposing many patients with low risk of recurrence to treatments for whom the benefit is not justified by the toxicity and the cost. In this article, we review the clinical and pathologic prognostic factors in early stage, node-negative breast cancer patients, including tumor size, nuclear and histologic grades, estrogen and progesterone receptors, menopausal status, proliferative rate, HER-2/neu oncogene amplification, and cathepsin D level. Favorable prognostic factors include tumor size less than or equal to 2 cm, low nuclear and histologic grades, low S-phase fraction, diploid state, low cathepsin-D level, and positive estrogen and progesterone receptor status. The value of HER-2/neu oncogene overexpression is controversial, and further studies are needed to define its role as a prognostic factor in patients with node-negative breast cancer. Based on these prognostic factors, it is possible to identify subsets of patients who have a low risk of recurrence and would not benefit significantly from adjuvant systemic therapy.

Breast Neoplasms↗
PubMed1992

Human milk intake and growth faltering of rural Mesoamerindian infants.

To determine whether growth faltering during early infancy was attributable to inadequate intake of human milk, the nutrient intakes and growth of 30 Otomi infants from Capulhuac, Mexico, were studied at 4 or 6 mo of age. Growth was monitored monthly from 1 through 6 mo of age. The 2H dose-to-the-mother method was used to measure human milk intake. Energy, protein, lactose, and fat concentrations in milk were analyzed by standard techniques. Mean (+/- SD) human milk intakes were 885 +/- 145 and 869 +/- 150 g/d at 4 and 6 mo, respectively. Protein and lactose concentrations in milk were normal but fat and consequently energy concentrations were abnormally low. Energy intakes averaged 81 +/- 14 kcal.kg-1.d-1 at 4 mo and 72 +/- 14 kcal.kg-1.d-1 at 6 mo. Growth faltering by 6 mo was evidenced by the significant decline in growth velocities and National Center for Health Statistics Z scores. Weight gain at 6 mo was 8.1 +/- 3.5 g/d and length gain was 1.0 +/- 0.34 cm/mo. Weight-for-age and length-for-age Z scores were -0.81 +/- 0.94 and -1.51 +/- 0.83, respectively. Growth velocities were not significantly correlated with nutrient intakes. Growth faltering among the Otomi infants despite energy intakes comparable to those of breast-fed infants in more protected environments may have resulted from an increase in the need for nutrients or from a growth-limiting nutrient, other than energy, in their diet.

Adult↗
PubMed1992

Neonatal genetically lean and obese pigs respond differently to dietary cholesterol.

The impact of cholesterol exposure in early life on later cholesterol metabolism is not clearly understood. Sixteen newborn genetically lean and obese pigs were fed 0 or 5.0 g cholesterol/kg diet (0 or 0.5%) (liquid diets for 12 d, dry diets thereafter) for 33 d, after which they were all fed 10.0 g cholesterol/kg diet (1.0%) for 23 d. All animals were killed on d 56 and whole-body protein, fat and water were determined on the ground carcass. Dietary cholesterol had no consistent effect on growth rates or body composition. Mean fat content of lean pigs was 15.1% compared with 22.7% for obese pigs; corresponding values were 14.8 and 14.4% for protein and 65.5 and 58.3% for water. Concentrations of plasma total cholesterol, HDL cholesterol and apolipoproteins B and A-1 were increased by 0.5% dietary cholesterol in obese but not in lean piglets, although dietary cholesterol caused HDL and LDL size distribution profiles to shift toward larger-sized components in both strains. Plasma total cholesterol and apolipoprotein B concentrations rose two- to eightfold in all groups after the 1% cholesterol diet was consumed; these changes were accompanied by shifts in LDL and HDL size distribution profiles towards larger-sized components. With 1.0% cholesterol in the diet of all groups, HDL cholesterol concentration increased by approximately 50% in both groups of lean pigs and in obese pigs previously fed cholesterol, but did not increase further in obese pigs previously fed 0.5% cholesterol. The magnitude of the hypercholesterolemic response in lean pigs was blunted by previous exposure to 0.5% dietary cholesterol, but the response was accentuated in obese animals that had been previously exposed to 0.5% dietary cholesterol. These data provide evidence that genetic differences between obese and lean pigs affect their serum lipoprotein responses to high cholesterol intake.

Animals↗
PubMed1992

Determining energy expenditure in preterm infants: comparison of 2H(2)18O method and indirect calorimetry.

The doubly labeled water (2H(2)18O) method used to estimate total energy expenditure (EETotal) is particularly sensitive to analytic error in preterm infants, because of their high percentage of body water and the high ratio of water flux to CO2 production. To evaluate further use of this method, the EE of 12 preterm infants was measured by indirect calorimetry and 2H(2)18O simultaneously and continuously for 5 days. Initial infant weight, age, and postconceptional age were (means +/- SD) 1,674 +/- 173 g, 4.4 +/- 2.6 wk, and 34.6 +/- 1.6 wk, respectively. The indirect calorimeter system included an air-temperature-controlled chamber and heart rate monitor. EE was measured by indirect calorimetry for 85.6 +/- 4.7% of study time and estimated from the linear regression of heart rate on EE for 14.4 +/- 4.7% of study time. The 2H(2)18O method entailed an initial dose of 100 mg 2H2O and 250 mg 18O/kg and a final dose of 75 mg 18O/kg; urine was collected twice daily. 2H and 18O enrichments were measured by gas-isotope-ratio mass spectrometry. EE was calculated from measured 2H and 18O dilution spaces (NH, NO), turnover rates (kH, kO), and measured respiratory quotient. The ratio of 2H to 18O dilution spaces was 1.01 +/- 0.01 and the ratio of kO to kH was 1.16 +/- 0.04. Estimation of EE from 2H(2)18O and indirect calorimetry agreed within 1%, although individual variability in methods was large.

Anthropometry↗
PubMed1992

Effect of dietary fat and cholesterol level on growing pigs selected for three generations for high or low serum cholesterol at age 56 days.

Thirty-six female pigs selected for three generations for high (HS, n = 18) and low (LS, n = 18) serum cholesterol at 56 d of age were used to test the hypothesis that the two populations would respond differently to a high-fat, high-cholesterol diet (HD) and a low-fat, low-cholesterol diet (LD). The animals were four-way crosses (Chester White x Landrace x Large White x Yorkshire). All pigs were fed a standard corn-soybean meal starter diet from weaning (at 4 wk) to 8 wk of age and a grower diet from 8 to 12 wk of age. Initial serum total cholesterol concentration at 12 wk of age was higher (P less than .05) in HS than in LS pigs (94.6 vs 76.9 mg/dL, respectively). The effect of genetic background persisted throughout the 13-wk experiment (25 wk of age); there was no interaction between diet and genetic background in serum total cholesterol (final concentrations were 114.3 mg/dL in HS-HD; 107.0 mg/dL in HS-LD; 105.9 mg/dL in LS-HD; and 89.7 mg/dL LS-LD). Trends over time revealed significant effects of diet (P less than .01) and genetic background (P less than .01) on serum total cholesterol. There was no effect of genetic background on high-density lipoprotein-cholesterol concentration; high-density lipoprotein-cholesterol as a percentage of serum total cholesterol was similar for all groups: 43% for HS-HD, 48% for HS-LD, 42% for LS-HD, and 45% for LS-LD.(ABSTRACT TRUNCATED AT 250 WORDS)

Analysis of Variance↗