PubMed Health⌕ Search

Biomedical subjects

J R Cheng

Publications and source records attributed to J R Cheng.

11 recordsLinked to original sources
PubMed2005

A case-control study in Shanghai of fruit and vegetable intake and endometrial cancer.

In a population-based case-control study of 832 incident endometrial cancer cases and 846 frequency-matched controls among Chinese women in Shanghai, using a validated food-frequency questionnaire, dietary habits were estimated by in-person interviews. Total vegetable consumption was inversely associated with endometrial cancer risk (highest quartile vs lowest: OR=0.69, 95% CI 0.50-0.96). The risk was reduced with increasing intake of dark green/dark yellow vegetables (trend test, P=0.02), fresh legumes (trend test, P<0.01), and allium vegetables (trend test, P=0.04). Fruit consumption was unrelated to risk. These results suggest that high consumption of certain vegetables may reduce the risk of endometrial cancer.

Adult↗
PubMed2004

Correlation of blood sex steroid hormones with body size, body fat distribution, and other known risk factors for breast cancer in post-menopausal Chinese women.

OBJECTIVE: Estrogen plays a central role in breast cancer. It has been suggested that many known breast cancer risk factors may exert their effect via levels of endogenous sex hormones. The objective of this analysis is to evaluate the association between measures of body size, dietary macronutrient intake, and reproductive factors with levels of endogenous sex hormones among women living in Shanghai, China. METHODS: Included in this study were 420 post-menopausal healthy women randomly selected from the general population as controls who participated in the Shanghai Breast Cancer Study, a population-based case-control study conducted in Shanghai, China between 1996 and 1998. Comprehensive dietary and reproductive information was collected using a structured questionnaire during an in-person interview and anthropometrics were measured by trained interviewers according to a standard protocol. Hormone levels were log-transformed and Pearson correlation coefficients were calculated to determine the correlation between hormone levels and selected breast cancer risk factors. RESULTS: Measures of body size were strongly correlated with hormone levels. In particular, weight, waist circumference, and hip circumference were significantly positively correlated (p < 0.05) with levels of testosterone, estradiol, estrone, and significantly negatively correlated with sex hormone binding globulin. Macronutrient intake and reproductive factors were not correlated with endogenous sex hormone levels. CONCLUSIONS: These data suggest that breast cancer risk associated with measures of body size may be mediated, at least partially, by levels of endogenous sex hormones.

Adult↗
PubMed2000

Genetic polymorphism of cytochrome P450-1B1 and risk of breast cancer.

Cytochrome P450-1B1 (CYP1B1) is a major enzyme catalyzing the formation of genotoxic 4-hydroxyestradiol. This enzyme is also involved in the activation of polycyclic aromatic hydrocarbons and heterocyclic aromatic amines, mammary carcinogens in experimental animals. CYP1B1 is genetically polymorphic, and the variations in the CYP1B1 gene may be related to the risk of breast cancer. We evaluated this hypothesis among 186 breast cancer cases and 200 age-matched controls as part of a large population-based case-control study conducted in urban Shanghai during 1996 to 1998. Genomic DNA from cases and controls was analyzed for genetic polymorphism in codon 432 (Val-->Leu) of the CYP1B1 gene using a PCR-RFLP-based assay. The frequency of the Leu allele was 53% in cases and 46% in controls (P = 0.06). Compared with those with the Val/Val genotype, women with the Leu/Leu genotype had a 2.3-fold [95% confidence interval (CI), 1.2-4.5] elevated risk of breast cancer after adjusting for potential confounding variables. This positive association was more pronounced among postmenopausal women (Odds ratio, 3.1; 95% CI, 1.0-9.1) than premenopausal women (OR, 1.9; 95% CI, 0.8-4.3). Elevated risks of breast cancer associated with homozygosity for the Leu allele were observed in virtually all subgroups of women defined by major risk factors for breast cancer. The results from this study were consistent with recent findings from in vitro and animal experiments implicating a potentially important role of CYP1B1 in the etiology of human breast cancer.

Adult↗
PubMed1994

[Medicinal plants of Valerianaceae in China].

Based on field investigation and taxonomic research on the medicinal plants of Valerianaceae in China, twenty-two species and two subspecies of three genera in this family are reported. Also some new medicinal plant resources are supplemented, Latin names of some species are revised, distribution and medicinal uses of the species are spelled out and a key for the species is given.

China↗
PubMed1991

[The structure of glyeurysaponin].

A species of the genus Glycyrrhiza, G. eurycarpa P.C. Li recently reported as a new species growing in Gansu Province Xinjiang Autonomous Region has rarely been studied before on its chemical constituents. This paper reports the isolation and chemical elucidation of two triterpene glucosides named glyeurysaponin (K-4) and uralsaponin B (K-3) from this species collected in Jinta County, Gansu Province. Their chemical structures were elucidated by means of chemical and spectrometric analysis (UV, IR, MS, 1HNMR and 13CNMR) and were first reported to be present in this plant. Glyeurysaponin (K-4), C42H62O16 was obtained as white crystals, mp 288 degrees C (d), [alpha]18D + 22.5 degrees (c 0.62,60%MeOH). Its structure was found to be be 3 beta-hydroxy-11-oxo-olean-12-en-30-oic acid-3-O-beta-D-glucuronopyranosyl-(1----4)-beta-D-glucuronopyr anoside. Glyeurysaponin is a new triterpenoid saponin. The known saponin was identified to be 3 beta-hydroxy-11-oxo-olean-12-en-30-oic acid-3-O-beta-D-glucuronopyranosyl-(1----3)-beta-D-glucuronopyr anoside, uralsaponin B.

Glycyrrhiza↗
PubMed1991

[Neolignans from Piper polysyphorum C.DC].

Piper polysyphorum C.DC (Piperaceae) is indigenous to the southern part of China. In the course of screening for inhibitors of platelet activating factor (PAF), the nonpolar fraction was found to exhibit PAF inhibitory activity. One new neclignan named polysyphorin and three new enantiomeric forms of (+)-virolongin, (+)-grandisin and (+)-lancifolin D were isolated. Two known neolignans, wallichinine and hancinone D were also obtained from the same sources. The structure determination was based upon spectroscopic analysis (UV, IR, CD, MS, 1HNMR, 13CNMR, COSY) and derivative preparation. The structure for polysyphorin was established as threo-delta 7'-7-hydroxy-3,4,5,3',5'-pentamethoxy-8-O-4' -neolignan. It is a racemic enantiomer. The PAF inhibitory activities were reported.

Drugs, Chinese Herbal↗
PubMed1989

Photoaffinity labeling of platelet activating factor binding sites in rabbit platelet membranes.

A photoreactive, radioiodinated derivative of platelet activating factor (PAF), 1-O-(4-azido-2-hydroxy-3-iodobenzamido)undecyl-2-O-acetyl-sn- glycero-3-phosphocholine ([125I]AAGP), was synthesized and used as a photoaffinity probe to study the PAF binding sites in rabbit platelet membranes. The nonradioactive analog, IAAGP, induced rabbit platelet aggregation with an EC50 value of 3.2 +/- 1.9 nM as compared to 0.40 +/- 0.25 nM for PAF. Specific binding of [125I]AAGP to rabbit platelet membranes was saturable with a dissociation constant (Kd) of 2.4 +/- 0.7 nM and a receptor density (Bmax) of 1.1 +/- 0.2 pmol/mg protein. Photoaffinity labeling of platelet membranes with [125I]AAGP revealed several 125I-labeled components by sodium dodecyl sulfate-polyacrylamide gel electrophoresis. A protein species with apparent molecular weight of 52,000 was consistently observed and inhibited significantly by unlabeled PAF at nanomolar concentrations. The labeling was specific since the PAF antagonists, SRI-63,675 and L-652,731, at 1 uM also blocked the appearance of this band; whereas lysoPAF was not effective at the same concentration. These results suggest that the binding sites of PAF receptor in rabbit platelets reside in the polypeptide of Mr = 52,000.

Affinity Labels↗