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Biomedical subjects

F L Wong

Publications and source records attributed to F L Wong.

36 records · Page 2Linked to original sources
PubMed1993

Noncancer disease incidence in the atomic bomb survivors: 1958-1986.

Using the longitudinal data of the Adult Health Study (AHS) cohort collected during 1958-1986, we examined for the first time the relationship between exposure to ionizing radiation and the incidence of 19 nonmalignant disorders in the A-bomb survivors. Affected individuals were ascertained through the three-digit codes of the International Classification of Diseases which are encoded in the AHS database subsequent to diagnoses made on the basis of general laboratory tests, physical examinations, and history-taking conducted during biennial AHS examinations. The disease onset time was estimated using the mid-point between the AHS examination data when the disease was initially reported and the previously attended disease-free examination date. Dosimetry System 86 organ doses judged to be most appropriate were used. Tests of dose effects were performed assuming a linear relative risk model with stratified background incidence. For the entire study period, significant excess risk was detected for uterine myoma (P < 0.001), chronic liver disease and cirrhosis (P = 0.006), and thyroid disease (P < 0.0001), defined broadly as the presence of one or more of certain noncancerous thyroid conditions. The incidence of myocardial infarction was shown to be increased (P = 0.03) in later years (1968-1986) among the younger heavily exposed AHS subjects, confirming the results of the recent Life Span Study (LSS) noncancer mortality report on coronary heart disease. The findings for uterine myoma may serve as additional evidence indicating benign tumor growth as a possible consequence of radiation exposure. Our results indicating the involvement of radiation in the development of liver diseases are consistent with the report of increased mortality from liver cirrhosis with radiation dose in the LSS cohort. An effect of age at exposure was detected for nonmalignant thyroid disease (P = 0.02), with an increased risk for those exposed who were under 20 years of age, but not for older survivors. Thus the AHS data suggest that thyroid glands in the young are more radiosensitive not only to the development of malignancies, but also to the development of nonmalignant disorders as well. The findings hold independently of the dose effects observed for thyroid cancer. This study also shows that for the period 1958-1986 new occurrences of lens opacity are not increased with radiation dose (P = 0.39) in the AHS subjects.

Adult↗
PubMed1992

Longitudinal study of the association between ABO phenotype and total serum cholesterol level in a Japanese cohort.

The relationship between ABO blood phenotype and total serum cholesterol (TC) level was examined in a Japanese population to determine whether an elevated TC level is associated with phenotype A, as has been demonstrated in many West European populations. Such studies in nonwhite populations are scarce, and findings generally failed to demonstrate the relationship. Inconsistent results from cross-sectional studies of various racial groups with widely varying ages raised an age effect as a possible explanatory factor. It was also suggested that the ABO-TC association may not be apparent in populations with low fat intake or low mean cholesterol level. These hypotheses are addressed by examining long-term TC data collected serially from the unexposed controls of the atomic bomb survivors in Hiroshima and Nagasaki who were participants of the Adult Health Study program at the Atomic Bomb Casualty Commission-Radiation Effects Research Foundation between 1958 and 1986. The statistical method of growth curve analysis, through the mixed effect model of Laird and Ware [1982], was used to model age-dependent changes in cholesterol levels within individuals. The effects of the ABO polymorphism in modifying the resultant growth curve are examined. We demonstrate that TC levels are elevated on average by about 4 mg/dl in phenotype A compared to non-A in the Japanese (P < 0.00001), and that this relationship is maintained from early to late adulthood, independent of sex, body mass index, cohort status, or city of residence. Thus, phenotype A individuals may be more predisposed to cardiovascular disease through one of its major risk factors. This is the first study of the ABO-cholesterol association in the Japanese, and the first based on a cohort with longitudinally collected TC data.

ABO Blood-Group System↗
PubMed1990

Surveillance of severe pediatric undernutrition: conceptual and practical issues.

Despite a high level of concern among health professionals and the general public, data are inadequate to define and monitor the prevalence of severe pediatric undernutrition (SPUN). The Centers for Disease Control is supporting four state health departments to test the feasibility of surveillance mechanisms for SPUN. These efforts will seek to develop workable case definitions, define prevalence estimates, identify high-risk populations and describe specific demographic, social and medical risk factors. Initial experience with SPUN surveillance indicates that a variety of approaches may prove feasible but that these require attention to issues such as measurement error, data collection burden, confidentiality and data management. SPUN surveillance may prove too costly to be practical for general application, but it can serve as a means to identify needy children and estimate the prevalence of undernutrition in specific high-risk populations.

Centers for Disease Control and Prevention, U.S.↗
PubMed1990

Methodological issues in nutrition surveillance: the CDC experience.

Nutrition surveillance systems serve to provide state- and locality-specific data that are useful for the management of public health nutrition programs. Current systems, such as the Pediatric and Pregnancy Nutrition Surveillance Systems coordinated by the Centers for Disease Control (CDC), collect program-based data focused on nutrition problems in infants, children, and pregnant women. These systems provide highly useful information, but also present significant methodological challenges relating to representativeness, quality control, and indicator sensitivity/specificity. As the importance of nutritional risk factors for chronic disease is increasingly recognized, the concept of nutrition surveillance must be expanded beyond maternal and child nutrition to include nutrition-related behaviors and risk factors in adolescents and adults. The Behavioral Risk Factor Surveillance System (BRFSS), coordinated by CDC, collects telephone survey data that include information on nutrition-related issues such as overweight, weight-loss practices, and cholesterol screening. In addition, a school-based surveillance system is being established by CDC in coordination with state education agencies to assess adolescent health behaviors, including nutrition. The operation of these nutrition surveillance systems presents significant methodological issues that must be considered in interpreting and using the data for public health purposes.

Adolescent↗
PubMed1989

Clinical results in carcinoma of the cervix: radium compared to caesium using remote afterloading.

In 1979 the Cancer Control Agency of British Columbia changed from radium to remote controlled afterloaded caesium in the treatment of carcinoma of the cervix. In the 3 years prior to the change, 139 patients received radium as part of their treatment and in the 3 years after the change, 158 patients received caesium. Overall referral patterns, patient and cancer demographics, and treatment policies were stable throughout the 6-year period. Radiotherapy technique, dose, dose distribution and dose rate were comparable for both radium and caesium treated patients. The results of treatment in the two time periods showed no difference in survival, local tumour control or complications. The use of afterloading has not compromised treatment results and has allowed better nursing care for patients and protection from radiation for all staff.

Brachytherapy↗
PubMed1987

Osteoradionecrosis: clinical experience and a proposal for classification.

Osteoradionecrosis is a severe complication of radiation therapy for cancer. Prevention of osteoradionecrosis is most important as the condition may be chronic, progressive and lead to pathologic fracture. The clinical experience at the Cancer Control Agency of British Columbia with 26 cases in approximately 1000 patients treated with radical radiation therapy to the head and neck region is presented and discussed. A clinical classification system is proposed to provide a guide for treatment selection, and to allow classification for research purposes.

Adult↗
PubMed1986

Sample-size considerations and strategies for linkage analysis in autosomal recessive disorders.

The opportunity raised by recombinant DNA technology to develop a linkage marker panel that spans the human genome requires cost-efficient strategies for its optimal utilization. Questions arise as to whether it is more cost-effective to convert a dimorphic restriction enzyme marker system into a highly polymorphic system or, instead, to increase the number of families studied, simply using the available marker alleles. The choice is highly dependent on the population available for study, and, therefore, an examination of the informational content of the various family structures is important to obtain the most informative data. To guide such decisions, we have developed tables of the average sample number of families required to detect linkage for autosomal recessive disorders under single backcross and under "fully informative" matings. The latter cross consists of a marker locus with highly polymorphic codominant alleles such that the parental marker genotypes can be uniquely distinguished. The sampling scheme considers families with unaffected parents of known mating types ascertained via affected offspring, for sibship sizes ranging from two to four and various numbers of affected individuals. The sample-size tables, calculated for various values of the recombination fractions and lod scores, may serve as a guide to a more efficient application of the restriction fragment length polymorphism technology to sequential linkage analysis.

DNA Restriction Enzymes↗
PubMed1985

A genetic component to the variation of dehydroepiandrosterone sulfate.

Previous studies have shown wide variation in the normal range of serum concentrations of adrenal androgens, including dehydroepiandrosterone (DHA), and DHA sulfate (DHAS). Much of this variability has been shown to be due to the marked variation of the concentrations of these hormones with age. In a search for other sources of this variation, we examined the distribution of DHAS levels in 178 individuals drawn from 26 families. DHAS was chosen because of its relatively high serum concentration, long half-life, and lack of pulsatile variation. As expected, we observed a large age effect, such that it accounted for 68% of the overall variability. In addition, however, when age was factored out by appropriate polynomial regression, there was a significant genetic component to the residual variation, with a heritability of 65%. Thus there appeared to be a significant genetic determination to DHAS serum levels. The results are in accord with previous studies suggesting a genetic component to the variation in testosterone and sex hormone globulin concentrations, and the known correlation of DHAS and testosterone levels. Thus there appears to be significant genetic control of androgen concentrations in humans.

Adolescent↗
PubMed1984

Sample-size calculations in segregation analysis.

Segregation analysis, employing nuclear families, is the most frequently used method to evaluate the mode of inheritance of a trait. To our knowledge, there exists no tabular information regarding the sample sizes required of individuals and families needed to perform a significance test of a specific segregation ratio for a predetermined power and significance level. To fill this gap, we have developed sample-size tables based on the asymptotic variance of the maximum likelihood estimate of the segregation ratio and on the normal approximation for two-sided hypothesis testing. Assuming homogeneous sibship size, minimum sample sizes were determined for testing the null hypothesis for the segregation ratio of 1/4 or 1/2 vs. alternative values of .05-.80, for the significance level of .05 and power of .8, for ascertainment probabilities of nearly 0 to 1.0, and sibship sizes 2-7. The results of these calculations indicate a complex interaction of the null and the alternate hypotheses, ascertainment probability, and sibship size in determining the sample size required for simple segregation analysis. The accompanying tables should aid in the appropriate design and cost assessment of future genetic epidemiologic studies.

Epidemiologic Methods↗
PubMed1982

Evidence for a major dominance component in the variation of serum pepsinogen I levels.

We report here a variance component analysis of the distribution of serum pepsinogen I levels in normal individuals, using a maximum-likelihood method on entire pedigrees. The results indicate a broad heritability of 91%, with some 74% being attributed to a dominance component. This is consistent with the hypothesis that the pepsinogen I level in normals is principally determined by the action of major genes, as also seems to be the case for duodenal ulcer patients and families.

Analysis of Variance↗
PubMedDate not supplied

Cancer mortality following treatment for adult hyperthyroidism. Cooperative Thyrotoxicosis Therapy Follow-up Study Group.

CONTEXT: High-dose iodine 131 is the treatment of choice in the United States for most adults with hyperthyroid disease. Although there is little evidence to link therapeutic (131)I to the development of cancer, its extensive medical use indicates the need for additional evaluation. OBJECTIVE: To evaluate cancer mortality among hyperthyroid patients, particularly after (131)I treatment. DESIGN: A retrospective cohort study. SETTING: Twenty-five clinics in the United States and 1 clinic in England. PATIENTS: A total of 35 593 hyperthyroid patients treated between 1946 and 1964 in the original Cooperative Thyrotoxicosis Therapy Follow-up Study; 91 % had Graves disease, 79% were female, and 65% were treated with (131)I. MAIN OUTCOME MEASURE: Standardized cancer mortality ratios (SMRs) after 3 treatment modalities for hyperthyroidism. RESULTS: Of the study cohort, 50.5% had died by the end of follow-up in December 1990. The total number of cancer deaths was close to that expected based on mortality rates in the general population (2950 vs 2857.6), but there was a small excess of mortality from cancers of the lung, breast, kidney, and thyroid, and a deficit of deaths from cancers of the uterus and the prostate gland. Patients with toxic nodular goiter had an SMR of 1.16 (95% confidence interval [CI], 1.03-1.30). More than 1 year after treatment, an increased risk of cancer mortality was seen among patients treated exclusively with antithyroid drugs (SMR, 1.31; 95% CI, 1.06-1.60). Radioactive iodine was not linked to total cancer deaths (SMR, 1.02; 95% CI, 0.98-1.07) or to any specific cancer with the exception of thyroid cancer (SMR, 3.94; 95% CI, 2.52-5.86). CONCLUSIONS: Neither hyperthyroidism nor (131)I treatment resulted in a significantly increased risk of total cancer mortality. While there was an elevated risk of thyroid cancer mortality following (131)I treatment, in absolute terms the excess number of deaths was small, and the underlying thyroid disease appeared to play a role. Overall, (131)I appears to be a safe therapy for hyperthyroidism.

Adult↗
PubMedDate not supplied

Bone and gallium scans in postradiotherapy osteonecrosis of the jaw.

The role of radiographic and nuclear imaging in evaluation of postradiotherapy osteonecrosis of the jaw was studied. Patients who had received imaging at diagnosis and following hyperbaric oxygen therapy were studied. Radiographic changes did not correlate with the clinical status of patients. All bone scans were abnormal at the time of diagnosis of osteonecrosis, but remained abnormal following changes in the clinical status of patients. Thus, the bone scan may aid in the detection of osteonecrosis. Gallium uptake did not aid i diagnosis, but did correlate with clinical findings following treatment. Persisting positive gallium scans may indicate the need for surgery following hyperbaric oxygen therapy.

Adult↗
PubMedDate not supplied

Topical bleomycin treatment of oral leukoplakia: a randomized double-blind clinical trial.

BACKGROUND: Oral leukoplakia and oral erythroplakia may be associated with benign and dysplastic cellular changes, and are at risk of malignant transformation. Additional means of management of these lesions is needed. The results of nonblinded trials using topical bleomycin in oral leukoplakia indicated the need for phase III study. METHODS: A prospective, double-blind, randomized trial of topical bleomycin versus placebo was conducted. Bleomycin 1% in dimethylsulphoxide (DMSO) or the carrier was applied for 5 minutes for 14 consecutive days. Clinical assessment and pre-application and post-treatment biopsies were conducted. RESULTS: Twenty-two patients were randomized. Of the patients who received bleomycin, decrease in clinical size of the lesion was achieved (p = 0.001), and histological reduction in dysplasia was seen (p = 0.094). CONCLUSIONS: The topical application of bleomycin in DMSO may represent an additional approach to management of oral leukoplakia. The treatment is well-tolerated, and may be considered when the location or extent of the lesion may make surgical excision difficult.

Administration, Topical↗
PubMedDate not supplied

A training workshop on late-stage dementia care for family caregivers.

Training workshops have been considered a useful intervention in helping family caregivers of people with dementia to cope with the stress of caregiving. However, there are no reports in the literature with regard to training and support of families specifically looking after individuals who are in the late stage of dementia. This paper reports the experience and evaluation of a training workshop aimed at preparing family caregivers for late-stage dementia care. Eighty-eight percent of the participants completed the client satisfaction questionnaire. The results from the questionnaire gave a very positive response, showing 90.9 percent of respondents were satisfied with the workshop, and 77.3 percent of respondents indicated that their caregiving needs were met. Eleven participants who attended this workshop joined a focus group feedback session. The Kruskal-Wallis test found no significant differences between the overall profile of the participants and that of the focus group in terms of age, gender, educational background, whether they were primary caregivers, for whom they cared (e.g., parents or spouse), or whether the care recipient stayed at home or in a nursing home. Findings from the focus group session provide a somewhat different picture from that of the questionnaire. Three focus group participants provided more critical comments of the workshop. Although the majority of the focus group agreed that the workshop had been useful, they disagreed on whether it is necessary to discuss psychosocial issues in this workshop. Findings from the focus group have enabled the project team to reflect on their design and operation of the workshop and provided valuable insight for future development as well as for further study.

Alzheimer Disease↗
PubMedDate not supplied

Using linked program and birth records to evaluate coverage and targeting in Tennessee's WIC program.

Public health nutrition programs are intended to serve low-income families who are at greater nutritional risk than the general population. Not all persons who are program-eligible are at equal risk, however. It would be desirable to evaluate a program's ability to enroll persons from higher risk backgrounds in the population (coverage) and, conversely, the extent to which those enrolled in this program are at higher risk (targeting). A method for the evaluation of coverage and targeting was developed using data from the Tennessee Women, Infants, and Children Special Supplemental Food Program (WIC) linked with birth certificates. The linked computer file was created by matching the name and date of birth in both record files. The birth records were the common source of information used to characterize the risk background for both the WIC and non-WIC participants. Maternal sociodemographic information on the birth records was used to define the health risk background of each child. The coverage and targeting of "at-risk" children were computed and compared for 50 counties or county-aggregates in Tennessee. Considerable variation in the coverage and targeting rates of at-risk children was observed among Tennessee counties, although the counties within each WIC administrative region tended to have similar coverage and targeting patterns. Using the existing data in linked program and vital records provides a direct evaluation of a program. Coverage and targeting evaluation can be used to detect underserved populations within small geographic areas.

Birth Certificates↗