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De-Kun Li

Publications and source records attributed to De-Kun Li.

9 recordsLinked to original sources
PubMed2006

Joint effects of the CYP1A1 MspI, ERalpha PvuII, and ERalpha XbaI polymorphisms on the risk of breast cancer: results from a population-based case-control study in Shanghai, China.

Estrogen-metabolizing gene and estrogen receptor (ER) genes are the possible risk factors implicated in the initiation and development of breast through estrogen tumorigenesis pathway. We examined whether CYP1A1 MspI, ERalpha PvuII, and ERalpha XbaI genetic polymorphisms could increase the risk of breast cancer among Chinese women and gene-gene joint effect on the breast cancer risk in a subset from a population-based case-control study conducted in urban Shanghai from January 1, 1998 and November 31, 2001. PCR-RFLP method based on buccal cells was used to examine the three candidate polymorphisms in 282 breast cancer cases and 298 controls. Compared with CYP1A1 MspI m1/m1, the risk of breast cancer was doubled for genotypes CYP1A1 MspI m1/m2 [odds ratio (OR), 1.83; 95% confidence interval (95% CI), 1.24-2.69] and CYP1A1 MspI m2/m2 (OR, 2.22; 95% CI, 1.26-3.85). The association seemed to be stronger among cases diagnosed older than 45 years and women without a family history of breast cancer. ERalpha PvuII pp and ERalpha XbaI xx polymorphisms, which are in possible linkage disequilibrium, were both associated with a nonsignificantly elevated risk in all subjects; the associations seemed to be stronger among women with a family history of breast cancer. There seems to be a joint effect on the breast cancer risk between CYP1A1 MspI and ERalpha XbaI genotypes (m2/m2 and xx; OR, 5.87; 95% CI, 1.38-24.98), between CYP1A1 MspI and ERalpha PvuII genotypes (m2/m2 and pp; OR, 2.39; 95% CI, 0.81-7.07), and among all three genotypes (m2/m2, pp, and xx; OR, 8.07; 95% CI, 1.45-44.77). Results of this study indicate that estrogen-metabolizing genes and estrogen receptor may jointly play a role in the etiology of breast cancer.

Adult↗
PubMed2005

Use of a dummy (pacifier) during sleep and risk of sudden infant death syndrome (SIDS): population based case-control study.

OBJECTIVES: To examine the association between use of a dummy (pacifier) during sleep and the risk of sudden infant death syndrome (SIDS) in relation to other risk factors. DESIGN: Population based case-control study. SETTING: Eleven counties in California. PARTICIPANTS: Mothers or carers of 185 infants whose deaths were attributed to SIDS and 312 randomly selected controls matched for race or ethnicity and age. MAIN OUTCOME MEASURE: Use of a dummy during sleep determined through interviews. RESULTS: The adjusted odds ratio for SIDS associated with using a dummy during the last sleep was 0.08 (95% confidence interval 0.03 to 0.21). Use was associated with a reduction in risk in every category of sociodemographic characteristics and risk factors examined. The reduced risk associated with use seemed to be greater with adverse sleep conditions (such as sleeping prone or on side and sleeping with a mother who smoked), although the observed interactions were not significant. In addition, use of a dummy may reduce the impact of other risk factors for SIDS, especially those related to adverse sleep environment. For example, infants who did not use a dummy and slept prone or on their sides (v on their back) had an increased risk of SIDS (2.61, 1.56 to 4.38). In infants who used dummies, there was no increased risk associated with sleeping position (0.66, 0.12 to 3.59). While cosleeping with a mother who smoked was also associated with increased risk of SIDS among infants who did not use a dummy (4.5, 1.3 to 15.1), there was no such association among those who did (1.1, 0.1 to 13.4). CONCLUSIONS: Use of a dummy seems to reduce the risk of SIDS and possibly reduces the influence of known risk factors in the sleep environment.

Adult↗
PubMed2004

Transmission of parentally shared human leukocyte antigen alleles and the risk of preterm delivery.

OBJECTIVE: Our objective was to examine our hypothesis that the transmission of parentally shared human leukocyte antigen (HLA) alleles to offspring increases the risk of preterm delivery. METHODS: A population-based family study with participating children and their parents was conducted in Kaiser Permanente Medical Care Program, an integrated healthcare delivery system, in the Northern California Region. A total of 234 participants from 78 families with early preterm deliveries (35 weeks of gestation or greater) and 60 participants from 20 families with full-term births were included in the study. Buccal cells were collected from the first-born preterm cases and their parents to determine HLA-B (class I) and DRB1 (class II) types and the transmission of parental alleles to the offspring. The buccal samples were also collected from full-term deliveries to rule out possible segregation distortion at the studied HLA loci. RESULTS: Compared with the expected transmission probability based on Mendel's laws (25%), transmission of parentally shared HLA-B or DRB1 alleles from both heterozygous parents to offspring (48% of 23 heterozygous parents) was associated with a more than 5-fold increased risk of preterm delivery (odds ratio 5.5; 95% confidence interval 1.2-51). Transmission of parentally shared HLA alleles from heterozygous mothers (83%) appears to be more important in the etiology of preterm delivery than transmission from fathers (57%). The transmission pattern of parentally shared HLA alleles in our full-term controls was almost identical to the expected pattern based on Mendel's laws and demonstrated no segregation distortion at those HLA loci. CONCLUSION: Our findings provide evidence that the transmission of parentally shared HLA alleles may be an underlying mechanism for preterm delivery.

Alleles↗
PubMed2003

Hot tub use during pregnancy and the risk of miscarriage.

To examine whether hot tub or whirlpool bath use during pregnancy increases the risk of miscarriage, the authors conducted a 1996-1998 population-based prospective cohort study at the Kaiser Permanente Medical Care Program in Oakland, California. Of 2729 eligible women, 1063 completed the interview. Miscarriage before 20 weeks of gestation was ascertained for all participants. Information on hot tub or whirlpool bath use was obtained during an in-person interview conducted early in the pregnancy. A Cox proportional hazards model was used to estimate the hazard ratio after adjustment for potential confounders. Compared with nonuse, use of a hot tub or whirlpool bath after conception was associated with a twofold increased risk of miscarriage (adjusted hazard ratio (aHR) = 2.0, 95% confidence interval: 1.3, 3.1). The risk seemed to increase with increasing frequency of use (aHR = 1.7 for less than once a week, aHR = 2.0 for once a week, and aHR = 2.7 for more than once a week) and with use during early gestation (aHR = 2.3 for initial use within the first 4 weeks of the last menstrual period and aHR = 1.5 for initial use after 4 weeks of the last menstrual period). Findings suggest an association between use of a hot tub or whirlpool bath during early pregnancy and the risk of miscarriage.

Abortion, Spontaneous↗
PubMed2003

Exposure to non-steroidal anti-inflammatory drugs during pregnancy and risk of miscarriage: population based cohort study.

OBJECTIVE: To evaluate whether prenatal use of non-steroidal anti-inflammatory drugs (NSAIDs) is associated with increased risk of miscarriage. DESIGN: Population based cohort study. Prenatal use of NSAIDs, aspirin, and paracetamol (acetaminophen) ascertained by in-person interview. SETTING: Kaiser Permanente Medical Care Program, a healthcare delivery system, in the San Francisco area of the United States. PARTICIPANTS: 1055 pregnant women recruited and interviewed immediately after their positive pregnancy test. Median gestational age at entry to the study was 40 days. MAIN OUTCOME MEASURES: Pregnancy outcomes up to 20 weeks of gestation. RESULTS: 53 women (5%) reported prenatal NSAID use around conception or during pregnancy. After adjustment for potential confounders, prenatal NSAID use was associated with an 80% increased risk of miscarriage (adjusted hazard ratio 1.8 (95% confidence interval 1.0 to 3.2)). The association was stronger if the initial NSAID use was around the time of conception or if NSAID use lasted more than a week. Prenatal aspirin use was similarly associated with an increased risk of miscarriage. However, prenatal use of paracetamol, pharmacologically different from NSAIDs and aspirin, was not associated with increased risk of miscarriage regardless of timing and duration of use. CONCLUSION: Prenatal use of NSAIDs and aspirin increased the risk of miscarriage. These findings need confirmation in studies designed specifically to examine the apparent association.

Abortion, Spontaneous↗
PubMed2003

Infant sleeping position and the risk of sudden infant death syndrome in California, 1997-2000.

To assess the association between infant sleeping position and risk of sudden infant death syndrome (SIDS) in an ethnically diverse US population, the authors conducted a population-based case-control study in 11 counties in California from May 1997 through April 2000. The authors conducted in-person interviews with the mothers of 185 SIDS cases and 312 randomly selected race/ethnicity- and age-matched controls to collect information on sleeping positions. Infants who had last been put down to sleep in the prone or side position were at greater risk of SIDS than were infants who had last been put down on their backs (adjusted odds ratio (AOR) = 2.6 (95% confidence interval (CI): 1.5, 4.5) and AOR = 2.0 (95% CI: 1.2, 3.4) for the prone and side positions, respectively). The risk of SIDS was especially high for an unstable side position in which an infant was placed on its side and found prone (AOR = 8.7, 95% CI: 3.3, 22.7). Infants who were usually placed on their backs to sleep but had last been put down in the prone or side position (an unaccustomed position) had a significantly high risk of SIDS (AOR = 8.2 (95% CI: 2.6, 26.0) and AOR = 6.9 (95% CI: 2.3, 20.6) for the prone and side positions, respectively). Infants placed in an unaccustomed prone or side sleeping position had a higher risk of SIDS than infants who were always placed prone or on the side.

California↗
PubMed2002

A population-based prospective cohort study of personal exposure to magnetic fields during pregnancy and the risk of miscarriage.

To study the effect of magnetic fields on the risk of miscarriage, we conducted a population-based prospective cohort study among pregnant women within a large health maintenance organization. All women with a positive pregnancy test at less than 10 weeks of gestation and residing in the San Francisco area were contacted for participation in the study. We conducted in-person interviews to obtain information on risk factors for miscarriage and other potential confounders. All participants were also asked to wear a magnetic field-measuring meter for 24 hours and to keep a diary of their activities. Pregnancy outcomes were obtained for all participants by searching the health maintenance organization's databases, reviewing medical charts, and telephone follow-up. We used the Cox proportional hazard model for examining the magnetic field-miscarriage association. A total of 969 subjects were included in the final analyses. Although we did not observe an association between miscarriage risk and the average magnetic field level, miscarriage risk increased with an increasing level of maximum magnetic field exposure with a threshold around 16 milligauss (mG). The rate ratio (RR) associated with magnetic field exposure > or = 16 mG (vs <16 mG) was 1.8 [95% confidence interval (CI) = 1.2-2.7]. The risk remained elevated for levels (in tertiles) of maximum magnetic field exposure > or = 16 mG. The association was stronger for early miscarriages (<10 weeks of gestation) (RR = 2.2, 95% CI = 1.2-4.0) and among "susceptible" women with multiple prior fetal losses or subfertility (RR = 3.1, 95% CI = 1.3-7.7). After excluding women who indicated that their daily activity pattern during the measurements did not represent their typical daily activity during pregnancy, the association was strengthened; RR = 2.9 (95% CI = 1.6-5.3) for maximum magnetic field exposure > or = 16 mG, RR = 5.7 (95% CI = 2.1-15.7) for early miscarriage, and RR = 4.0 (95% CI = 1.4-11.5) among the susceptible women. Our findings provide strong prospective evidence that prenatal maximum magnetic field exposure above a certain level (possibly around 16 mG) may be associated with miscarriage risk. This observed association is unlikely to be due to uncontrolled biases or unmeasured confounders.

Abortion, Spontaneous↗