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Biomedical subjects

A Chao

Publications and source records attributed to A Chao.

83 records · Page 5Linked to original sources
PubMed1988

Past and present preferred prescribing practices of hormone replacement therapy among Los Angeles gynecologists: possible implications for public health.

Usual prescribing strategies of hormone replacement therapy for postmenopausal women by Los Angeles area gynecologists, both now and 10 years ago, were investigated by a mail survey. Of the 330 gynecologists who responded, estrogen therapy is currently used as a routine by nearly all (95 per cent), for women both with and without a uterus. Over three-fourths of these physicians favor use of 0.625 mg of conjugated equine estrogen. The estrogen is combined with cyclic progestin therapy, usually 10 mg of medroxyprogesterone acetate, by 86 per cent of gynecologists using estrogen for women with a uterus, and by 47 per cent for women without a uterus. Although conjugated equine estrogens were used widely for both groups of patients 10 years ago, a higher dose generally was preferred. Use of progestin therapy was uncommon (less than 20 per cent) for any postmenopausal patients at that time. Although the most common monthly therapeutic regimen for estrogen/progestin therapy is estrogen for days 1-25 and progestin for days 16-25, there is wide variation in prescribing strategies. We present these findings in the context of the probable effects of estrogen/progestin therapy on various chronic disease outcomes.

Adult↗
PubMed1987

Use of preventive care by the elderly.

Use of five early disease detection tests was examined in relation to history of specific chronic disease and other health habits, as part of a cohort study including 11,888 residents of a retirement community in Southern California. Self-reported utilization rates by residents in the year preceding study entry were approximately 90, 30, 60, and 10% for blood pressure measurement, fecal occult blood test, Papanicolaou test, and mammography, respectively. Breast self-examination was practiced by 37% of the women on a regular basis. With the exception of the Pap test and blood pressure check, the majority of the study population did not use preventive procedures at the recommended frequencies. The most important determinants of use of screening tests in this elderly population were previous diagnosis of chronic disease, especially of the disease detected by the test itself, and having a regular physician. These two factors appeared to affect use independently.

Aged↗
PubMed1987

Estimating the population size for capture-recapture data with unequal catchability.

A point estimator and its associated confidence interval for the size of a closed population are proposed under models that incorporate heterogeneity of capture probability. Real data sets provided in Edwards and Eberhardt (1967, Journal of Wildlife Management 31, 87-96) and Carothers (1973, Journal of Animal Ecology 42, 125-146) are used to illustrate this method and to compare it with other estimates. The performance of the proposed procedure is also investigated by means of Monte Carlo experiments. The method is especially useful when most of the captured individuals are caught once or twice in the sample, for which case the jackknife estimator usually does not work well. Numerical results also show that the proposed confidence interval performs satisfactorily in maintaining the nominal levels.

Animals↗
PubMed1987

Vitamin A, beta-carotene, and the risk of cancer: a prospective study.

A cohort of 10,473 residents of Leisure World, Laguna Hills, CA, who were initially free of cancer were followed from 1981 to 1986. A health survey questionnaire completed by all cohort members included usual frequencies of consumption of certain food items, including vegetables, fruits, dairy products, liver, and cereal, as well as specific information on brand and formulation of vitamin supplements containing vitamins A, C, or E. Pathologic diagnosis of incident cancer was confirmed in 643 persons (56 lung, 110 colon, 59 bladder, 93 prostate, 123 female breast, and 202 cancers of other sites). Our study found little indication that increased intake of vitamin A or beta-carotene from the diet or supplements protects against the development of cancer overall. Dietary vitamin A intake was highly associated with smoking status; 25% of current smokers were in the highest third of dietary vitamin A consumption versus 32% of past smokers and 36% of never-smokers. In males who never smoked there was some indication that cancer rates decreased with increasing vitamin A intake, but the results were not statistically significant.

Carotenoids↗
PubMed1986

Increased frequency of adenocarcinoma of the uterine cervix in young women in Los Angeles County.

By hypothesizing that oral contraceptives (OC's) might have a carcinogenic effect on glandular cells of the cervix if given during periods of active metaplasia (e.g., postmenarchal adolescence), an increasing rate of cervical adenocarcinoma was predicted in young women who had been teenagers when OC's were introduced roughly 20 years ago. Secular trends for cervical carcinomas in non-Hispanic whites were examined by age, histologic type, and social class by using data from the Los Angeles County population-based tumor registry. Between 1972 and 1982, the frequency of invasive cervical adenocarcinoma in women under 35 years of age increased from about 2 to about 5 annually, amounting to an average rate of change of 8% per year (P less than .01). There was essentially no trend for women over 35 years old; the frequency of other invasive carcinomas (and of squamous carcinoma in situ) decreased at average rates of about 3% per year in women under 35 years of age and decreased more rapidly in older women. The increase in adenocarcinoma, unlike risk from cervical cancer generally, was most striking among young women residing in middle-to-upper income neighborhoods, who were the first to use OC's; in this subgroup the average rate of increase was 16% per year (P less than .05). These findings are compatible with our hypothesis and merit further study.

Adenocarcinoma↗
PubMed1983

The value of endometrial histology in suggesting the presence of ectopic gestation.

The practicality of endometrial histology for suggesting the possibility of ectopic gestation was evaluated by a review of two years' experience at the Naval Regional Medical Center, Portsmouth, Virginia. Using various histologic criteria, we could not predict the presence of ectopic pregnancy. The false-positive rate when we used standard histologic criteria was 97%. The effort on the part of the pathology department to exclude intrauterine pregnancy by through examination of endometrial material was a fruitless exercise and also unnecessarily raised medical costs.

Endometrium↗
PubMed1977

Mathematical description of solute velocities during dissolution from a horizontal surface.

A mathematical analysis of solute flow in a descending column following dissolution is presented. The acceleration of a solute particle from zero velocity, when it is in the solid phase, to its final equilibrium descending velocity was analyzed. The maximum velocity for N-(3-methylphenyl) acetamide developed essentially at the solid-liquid interface, contradicting the postulate of a microsize diffusional layer. The possibility of a diffusional layer existing for solids of lower solubility than N-(3-methylphenyl)acetamide is discussed.

Acetamides↗
PubMed1976

Spironolactone. II. Bioavailability.

The bioavailability of commercial 25-mg spironolactone tablets and a new tablet preparation containing 100 mg of the drug has been determined in 12 healthy male subjects. After a 200-mg oral dose of the drug given in a solution of polyethylene glycol-400, the peak plasma level of the dethioacetylated metabolite canrenone was 633 +/- 154 ng/ml (mean +/- SD) and was reached at 1.4 +/- 0.43 hr. This peak was higher and was achieved earlier than after either eight 25-mg tablets (480 +/- 155 ng/ml at 2.9 +/- 1.03 hr) or two 100-mg tablets (474 +/- 182 ng/ml at 3.0 +/- 1.37 hr). From the ratio of the 24-hr area under the plasma concentration-time curves, the bioavailabilities of the two tablet preparations relative to the solution were 99.6 +/- 18.2% and 92.1 +/- 22.9%, respectively. The amount of canrenone excreted in the urine by 48 hr was 4.48 +/- 1.26 mg (solution), 6.36 +/- 2.02 mg (eight 25-mg tablets), and 7.81 +/- 1.87 mg (two 100-mg tablets), representing 2% to 4% of the administered dose. It is concluded that urinary excretion of canrenone alone is not a reliable method for determining the bioavailability of spironolactone.

Administration, Oral↗