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Biomedical subjects

S Y Chu

Publications and source records attributed to S Y Chu.

At least 91 records · Page 5Linked to original sources
PubMed1990

Cigarette smoking and the risk of breast cancer.

The authors examined the relation between cigarette smoking and breast cancer in the Centers for Disease Control Cancer and Steroid Hormone Study, a multicenter, population-based case-control study. The study compared 4,720 women aged 20-54 years with newly diagnosed breast cancer identified through population-based tumor registries with 4,682 women randomly selected from the same geographic areas. Women who reported ever smoking cigarettes had a risk of breast cancer of 1.2 (95 percent confidence interval 1.1-1.3) compared with never smokers. There was no consistent dose-response pattern with any measure of smoking (pack-years of smoking, average number of cigarettes per day, or total years smoked) and little difference in risk between current and former smokers. There was some variation in risk by age, with slightly higher risk estimates for younger women than for older women. Although current smokers had an earlier natural menopause than did never smokers, the authors found no evidence of a protective effect of cigarette smoking on breast cancer risk. These findings suggest that the risk of breast cancer in women who smoke is the same as, or perhaps slightly higher than, women who have never smoked.

Adult↗
PubMed1990

Epidemiology of reported cases of AIDS in lesbians, United States 1980-89.

National surveillance data for reported cases of acquired immunodeficiency syndrome (AIDS) were used to assess demographic characteristics and behavioral risk factors in lesbians. From June 1, 1980 through September 30, 1989, 79 women with AIDS reported sex relations only with a female partner; most of these women (95 percent) were intravenous drug users. Prevention of human immunodeficiency virus (HIV) infection in the lesbian community will require efforts to prevent and reduce intravenous drug use.

Acquired Immunodeficiency Syndrome↗
PubMed1990

Surveillance for AIDS and HIV infection among black and Hispanic children and women of childbearing age, 1981-1989.

Surveillance systems indicate that the most documented human immunodeficiency virus (HIV) infections and acquired immunodeficiency syndrome (AIDS) cases among children and women of childbearing age in the United States occur among black and Hispanic populations. Intravenous-drug use (IVDU) is the presumptive origin of HIV infection for most of these cases, through direct IVDU, sexual contact with an intravenous (IV)-drug user, or birth to women with either mode of exposure. These data confirm the need for HIV-prevention programs directed to the racial, ethnic, age, and reproductive concerns of black and Hispanic women of childbearing age and their children. Services should be available for those who are HIV infected, as well as for those who are not infected with HIV, to prevent the further spread of HIV. Services for prevention and treatment of drug abuse are an integral part of HIV prevention and treatment for these groups.

Acquired Immunodeficiency Syndrome↗
PubMed1990

Characteristics of women who considered or obtained tubal reanastomosis: results from a prospective study of tubal sterilization.

The Collaborative Review of Sterilization is a prospective study of women undergoing tubal sterilization at selected medical centers in the United States. This analysis examined 5817 study participants who were asked whether they had sought information on tubal reanastomosis after their sterilizations and whether they had actually obtained reanastomosis surgery. Characteristics that predicted the likelihood of seeking reanastomosis information were examined in multivariate, logistic regression models that included age, race, number of living children, history of abortion, education, timing of sterilization in relation to pregnancy, initial marital status, and change in marital status. Among the women studied, 6.2% reported that they had sought information on reanastomosis. Women who were younger than 30 years old at the time of sterilization were twice as likely to seek such information as women aged 30-34, and women who had experienced changes in martial status after sterilization were 2.8 times as likely to seek information as women with unchanged marital status. Thirteen women had actually obtained reanastomosis. Compared with the overall study population, these women were more likely to be white, to have lower gravidity, to be younger, and to have experienced changes in marital status.

Abortion, Induced↗
PubMed1989

A new colorimetric assay for purine nucleoside phosphorylase.

A new colorimetric procedure for the determination of purine nucleoside phosphorylase (PNP, E.C. 2.4.2.1) activity is described. In this procedure, the hydrogen peroxide formed in the PNP-xanthine oxidase reaction is used to oxidize the chromogenic reagents--3,5-dichloro-2-hydroxybenzenesulfonic acid/4-aminophenazone using the enzyme peroxidase. The rate of enzyme reaction is followed at 520 nm. This procedure correlated well with the UV method (290 nm), with a correlation coefficient of 0.98 (P less than 0.005). Within-run and between-run precision (CV) were less than 2.8% and 3.7%, respectively. Here we also describe an optimized NAD-dependent method (340 nm) for PNP determination. The colorimetric method is superior to both the 340 nm and the UV methods in terms of both sensitivity and precision. The mean erythrocyte PNP activity for 17 healthy subjects was 11.88 U/mL packed cells for the NAD-dependent method and 13.22 U/mL packed cells for the colorimetric method.

Chromogenic Compounds↗
PubMed1989

Purine nucleoside phosphorylase in erythrocytes: determination of optimum reaction conditions.

Reaction conditions for determining the activity of purine nucleoside phosphorylase (PNP; E.C. 2.4.2.1) were investigated. We examined the kinetic parameters for the enzymatic reaction with respect to the substrates inosine and phosphate. We confirmed the pH optimum, established the optimal concentration of xanthine oxidase and that of calcium and magnesium. The Km values for inosine and phosphate were found to be 60 uM and 667 uM, respectively. Optimum assay conditions for PNP activity were established. This optimized method has been compared with other procedures and found to be more sensitive and to yield significantly higher activities. The experimental variation of a manual procedure using these optimum reaction conditions was less than 4.5%. The mean erythrocyte PNP activity of 28 healthy subjects was estimated to be 9.71 U/mL packed cells at 25 degrees C and 18.60 U/mL packed cells at 37 degrees C.

Chemical Phenomena↗
PubMed1989

Alcohol consumption and the risk of breast cancer.

To examine the relation between alcohol consumption and breast cancer, the authors used data from the Centers for Disease Control's Cancer and Steroid Hormone Study, a multicenter population-based case-control study. Between August 1981 and December 1982, 3,498 US women aged 20-54 years with newly diagnosed breast cancer and 3,157 women aged 20-54 years selected at random from the same geographic areas were asked about their consumption of alcoholic beverages during the previous five years. Women who drank any alcohol had a risk of breast cancer of 1.0 (95% confidence interval 0.9-1.2) compared with nondrinkers. The risk of breast cancer did not increase appreciably with increasing alcohol consumption: Risk estimates for women consuming 8-14, 15-21, and 22 or more drinks per week were 1.1, 1.0, and 1.2, respectively. The authors also found no notable differences by type of beverage or within specific risk factor subgroups. These findings do not support the hypothesis that alcohol consumption increases the risk of breast cancer.

Adult↗
PubMed1988

Rubella antibody persistence after immunization. Sixteen-year follow-up in the Hawaiian Islands.

A comparative field trial of three rubella virus vaccines (Cendehill, HPV-77 DE-5, and HPV-77 DK-12) was initiated in 1969 on the islands of Kauai and Hawaii in the state of Hawaii. In 1985, follow-up was reinitiated to assess the long-term durability of vaccine-induced immunity. Enzyme-linked immunosorbent assays of serum specimens from 1290 participants demonstrated seropositive rates of 92.4% and 96.4% at screening levels of 10 (protective level) and 7 (lowest detectable level) IU/mL, respectively. The seropositive rates were not related to reinfection or reimmunizations. These findings indicate that vaccine-induced rubella antibodies are detectable in almost all persons up to 16 years after successful vaccination.

Antibodies, Viral↗
PubMed1986

Single-dose pharmacokinetics of leuprolide in humans following intravenous and subcutaneous administration.

A group of six normal adult male volunteers was divided into two groups (I and II) who received bolus intravenous and subcutaneous 1-mg doses of leuprolide. The study was of a randomized, complete-crossover design. Blood was collected from 0 to 48 h postdosing, and plasma was analyzed for leuprolide using a radioimmunoassay procedure. The data from the intravenous doses were fitted to a two-compartment open model with elimination from the central compartment, assuming a bolus (instantaneous) injection. The data from the subcutaneous doses were fitted to a two-compartment open model with elimination from the central compartment and first-order (monoexponential) absorption from the injection site. Statistical moments were also calculated for both sets of data. The mean beta half-life after the intravenous dosings was 2.9 h and after the subcutaneous dosings was 3.6 h. The difference between these two values, as well as those for plasma clearance, variance in residence time, and volume of distribution at steady state was not statistically significant; however, the differences between the mean values of k21, k12, kel, apparent volume of distribution of the central compartment, mean residence time, and area under the moment curve for the routes of administration were significant (p less than 0.05). The mean residence time following the intravenous dosings averaged 3.1 h and following the subcutaneous dosings averaged 4.3 h, indicating an average mean residence time at the subcutaneous injection site of 1.2 h. The mean volume of distribution at steady state from the intravenous and subcutaneous doses were 26.5 and 37.1 L, respectively.(ABSTRACT TRUNCATED AT 250 WORDS)

Adult↗
PubMed1986

Screening for congenital hypothyroidism in Hong Kong.

A pilot cord blood TSH screening program for congenital hypothyroidism was commenced in Hong Kong in April 1982. By April 1984, 14 411 neonates born in two hospitals were screened for this disorder. Five cases of primary hypothyroidism and two cases of transient hypothyroidism were detected. The detection of cases of congenital hypothyroidism with only moderately elevated cord blood TSH values means that the recall rate will remain high.

Congenital Hypothyroidism↗
PubMed1985

Depression of serum cholinesterase activity as an indicator for insecticide exposure--consideration of the analytical and biological variations.

Interest has recently been shown in the use of serum cholinesterase levels as a marker for chronic organophosphate insecticide exposure. Interpretation of the results must, however, take into account both long-term biological and analytical variations. The intraindividual variation of serum cholinesterase activity for 12 laboratory workers was 4.3%. The variation was much smaller than the interindividual variation of the whole population (20%). Based on the homogeneity of the intraindividual variance, it is possible to show the level of minimal decrease in enzyme activity which constitutes a departure from "normal".

Analysis of Variance↗
PubMed1984

The use of BMC Chemstrip 9 in the macroscopic urine screening procedure.

The usefulness of a stick test for detection of leukocyte esterase activity in urine as part of a "macroscopic screen" was examined, as well as the efficiency of our existing broad screening criteria for detecting abnormalities in urine without microscopic examination. In a study of 923 unselected urine samples submitted to the laboratory, a false-negative rate of 0.6% was observed as judged by microscopic examination. The results of our present studies tend to confirm the usefulness of our "screen" program. The new leukocyte esterase test has been demonstrated to be an important adjunct to the macroscopic screening program.

Esterases↗