Biomedical subjects

W Zheng

Publications and source records attributed to W Zheng.

At least 73 records · Page 4Linked to original sources

PubMed2001

GADD45gamma mediates the activation of the p38 and JNK MAP kinase pathways and cytokine production in effector TH1 cells.

The p38 and JNK stress-activated MAPK signal transduction pathways are activated by T cell receptor (TCR) signaling and are required for IFN-gamma production by TH1 effector cells. Here, we show that the expression of GADD45gamma is induced during T cell activation and that the level of expression is higher in TH1 cells than in TH2 cells. TH1 cells from GADD45gamma(-/-) mice are severely compromised in their abilities to activate p38 and JNK in response to TCR signaling, produce much less IFN-gamma upon restimulation, and are deficient in activation-induced cell death (AICD). Additionally, GADD45gamma deficiencies caused reduced contact hypersensitivity in mice. Thus, GADD45gamma mediates activation of the p38 and JNK pathways and effector function of TH1 cells.

Animals↗

PubMed2001

Effect of plant growth temperature on antioxidant capacity in strawberry.

The influence of four day/night growing temperature combinations (18/12, 25/12, 25/22, and 30/22 degrees C) on phenolic acid, flavonol, and anthocyanin content and their antioxidant activities against peroxyl radicals (ROO(*)), superoxide radicals (O(2)(*)(-)), hydrogen peroxide (H(2)O(2)), hydroxyl radicals (OH(*)), and singlet oxygen ((1)O(2)) in fruit juice of Earliglow and Kent strawberry (Fragaria x ananassa Duch.) cultivars was studied. Pelargonidin-based anthocyanins such as pelargonidin 3-glucoside (291.3-945.1 microg/g fresh wt.), pelargonidin 3-rutinoside (24.7-50.9 microg/g fresh wt.), and pelargonidin 3-glucoside-succinate (62.2-244.0 microg/g fresh wt.) were the predominant anthocyanins in strawberry fruit juice. The content of cyanidin-based anthocyanins, cyanidin 3-glucoside and cyanidin 3-glucoside-succinate, was much lower than that of pelargonidin-based anthocyanins. Strawberry growth in high temperature conditions significantly enhanced the content of p-coumaroylglucose, dihydroflavonol, quercetin 3-glucoside, quercetin 3-glucuronide, kaempferol 3-glucoside, kaempferol 3-glucuronide, cyanidin 3-glucoside, pelargonidin 3-glucoside, pelargonidin 3-rutinoside, cyanidin 3-glucoside-succinate, and pelargonidin 3-glucoside-succinate in strawberry juice. Plants grown in the cool day and cool night temperature (18/12 degrees C) generally had the lowest phenolic acid, flavonols, and anthocyanins. An increase in night temperature from 12 to 22 degrees C, with the day temperature kept constant at 25 degrees C, resulted in a significant increase in phenolic acid, flavonols, and anthocyanins. These conditions also resulted in a significant increase in antioxidant capacity. The highest day/night temperature (30/22 degrees C) yielded fruit with the most phenolic content as well as ROO(*), O(2)(*)(-), H(2)O(2), OH(*), and (1)O(2) radical absorbance capacity. Fruit of Kent cv. strawberry had higher values of phenolic acid, flavonols, anthocyanins, and antioxidant capacities than fruit of Earliglow cv. strawberry under all temperature regimes.

Anthocyanins↗

PubMed2001

Antioxidant activity and phenolic compounds in selected herbs.

The antioxidant capacities (oxygen radical absorbance capacity, ORAC) and total phenolic contents in extracts of 27 culinary herbs and 12 medicinal herbs were determined. The ORAC values and total phenolic contents for the medicinal herbs ranged from 1.88 to 22.30 micromol of Trolox equivalents (TE)/g of fresh weight and 0.23 to 2.85 mg of gallic acid equivalents (GAE)/g of fresh weight, respectively. Origanum x majoricum, O. vulgare ssp. hirtum, and Poliomintha longiflora have higher ORAC and phenolic contents as compared to other culinary herbs. The ORAC values and total phenolic content for the culinary herbs ranged from 2.35 to 92.18 micromol of TE/g of fresh weight and 0.26 to 17.51 mg of GAE/g of fresh weight, respectively. These also were much higher than values found in the medicinal herbs. The medicinal herbs with the highest ORAC values were Catharanthus roseus, Thymus vulgaris, Hypericum perforatum, and Artemisia annua. A linear relationship existed between ORAC values and total phenolic contents of the medicinal herbs (R = 0.919) and culinary herbs (R = 0.986). High-performance liquid chromatography (HPLC) coupled with diode-array detection was used to identify and quantify the phenolic compounds in selected herbs. Among the identified phenolic compounds, rosmarinic acid was the predominant phenolic compound in Salvia officinalis, Thymus vulgaris, Origanum x majoricum, and P. longiflora, whereas quercetin-3-O-rhamnosyl-(1 --> 2)-rhamnosyl-(1 --> 6)-glucoside and kaempferol-3-O-rhamnosyl-(1 --> 2)-rhamnosyl-(1 --> 6)-glucoside were predominant phenolic compounds in Ginkgo biloba leaves.

Antioxidants↗

PubMed2001

CspD, a novel DNA replication inhibitor induced during the stationary phase in Escherichia coli.

CspD is a stationary phase-induced, stress response protein in the CspA family of Escherichia coli. Here, we demonstrate that overproduction of CspD is lethal, with the cells displaying a morphology typical of cells with impaired DNA replication. CspD consists mainly of beta-strands, and the purified protein exists exclusively as a dimer and binds to single-stranded (ss)DNA and RNA in a dose-dependent manner without apparent sequence specificity. CsdD effectively inhibits both the initiation and the elongation steps of minichromosome replication in vitro. Electron microscopic studies revealed that CspD tightly packs ssDNA, resulting in structures distinctly different from those of SSB-coated DNA. We propose that CspD dimers, with two independent beta-sheets interacting with ssDNA, function as a novel inhibitor of DNA replication and play a regulatory role in chromosomal replication in nutrient-depleted cells.

Amino Acid Sequence↗

PubMed2001

Coordinate regulation of canine glomeruli and adrenal angiotensin receptors by dietary sodium manipulation.

BACKGROUND: This study evaluated the effects of dietary sodium manipulation in dogs on the regulation of canine angiotensin receptors (cAT1 and cAT2) in the kidney and adrenal. METHODS: Isolated glomeruli and membranes from renal medulla and the adrenal gland were used in radioligand binding assays from two groups of dogs: dogs maintained on low-sodium diet for two weeks followed by a high-sodium diet for two weeks (H), and dogs were maintained on the reverse schedule (L). RESULTS: Analysis of the binding data showed that dietary sodium manipulation had no significant effects on cAT1 and cAT2 receptor binding affinities in glomeruli, renal medulla, and adrenal tissues. In contrast, dietary sodium loading induced a marked increase in cAT1 receptor expression in both the glomeruli and adrenal compared with receptor expression in salt-restricted animals [H/L ratio: glomeruli (1.5), renal medulla (1.1), adrenal (1.6)] that inversely correlated with the activity of the plasma renin angiotensin system. Conversely, adrenal cAT2 receptor expression was regulated in an inverse manner in the H and L animal groups [H/L ratio: 0.7]. CONCLUSIONS: This study demonstrates that renal glomerular and adrenal AT1 receptors in the dog are coordinately down-regulated by dietary sodium restriction compared with sodium loading, which is distinctly different from the reciprocal regulation observed for rat AT1 receptors in these tissues. Collectively, these data suggest that postreceptor events in dogs are determinants of the aldosterone response observed during sodium restriction. These findings have important implications for the regulation of the renin-angiotensin system in humans, and suggest that coordinate regulation of AT1 receptors in the adrenal and glomeruli represent a negative feedback mechanism that when functioning normally prevents fluctuations of arterial blood pressure and development of arterial hypertension in response to changes in dietary sodium.

Adrenal Glands↗

PubMed2001

Neurotoxicology of the brain barrier system: new implications.

The concept of a barrier system in the brain has existed for nearly a century. The barrier that separates the blood from the cerebral interstitial fluid is defined as the blood-brain barrier, while the one that discontinues the circulation between the blood and cerebrospinal fluid is named the blood-cerebrospinal fluid barrier. Evidence in the past decades suggests that brain barriers are subject to toxic insults from neurotoxic chemicals circulating in blood. The aging process and some disease states render barriers more vulnerable to insults arising inside and outside the barriers. The implication of brain barriers in certain neurodegenerative diseases is compelling, although the contribution of chemical-induced barrier dysfunction in the etiology of any of these disorders remains poorly understood. This review examines what is currently understood about brain barrier systems in central nervous system disorders by focusing on chemical-induced neurotoxicities including those associated with nitrobenzenes, N-methyl-D-aspartate, cyclosporin A, pyridostigmine bromide, aluminum, lead, manganese, 1-methyl-4-phenyl-1,2,3,6-tetrahydropyridine, and 3-nitropropionic acid. Contemporary research questions arising from this growing understanding show enormous promises for brain researchers, toxicologists, and clinicians.

Aluminum↗

PubMed2001

Stray radiofrequency current as a cause of urethral strictures after transurethral resection of the prostate.

PURPOSE: This study was designed to define the pattern and significance of stray currents induced by two electrosurgical generators (ESGs) in relation to urethral strictures forming after transurethral resection of the prostate (TURP). MATERIALS AND METHODS: A 24F resectoscope irrigated with glycine was activated at various power outputs in different modes, with intact loops and loops with faulty insulation, simulating TURP. The Valleylab and ERBE ESGs were compared for inducing capacitance. An ESG analyzer simulated tissue impedance and recorded the stray currents induced along the resectoscope sheath. A fresh pig liver was used for assessment of tissue damage caused by the currents. RESULTS: In the cutting mode, the ERBE ESG produced a mean stray current of 70 mA with an intact loop and 144 mA with a loop having faulty insulation. The Valleylab ESG produced 150 mA and 161 mA, respectively. In the coagulation mode, the ERBE ESG produced an average leakage current of 35 mA and, with a loop with faulty insulation, 40 mA. The Valleylab ESG produced 148 mA and 151 mA, respectively. CONCLUSIONS: Electrical injury may represent a significant cause of urethral stricture after transurethral electrosurgery. The critical power density of 7.5 W/cm2 (which is likely to cause a urethral burn) may be reached, especially with the use of loops with faulty insulation or nonconductive lubricating gel. The ERBE ESG produced significantly less capacitance, decreasing the risk of urethral electrical burn. Conductive gel prevents dangerous current concentration.

Electric Injuries↗

PubMed2001

Transthyretin, thyroxine, and retinol-binding protein in human cerebrospinal fluid: effect of lead exposure.

Transthyretin (TTR), synthesized by the choroid plexus, is proposed to have a role in transport of thyroid hormones in the brain. Our previous studies in animals suggest that sequestration of lead (Pb) in the choroid plexus may lead to a marked decrease in TTR levels in the cerebrospinal fluid (CSF). The objectives of this study were to establish in humans whether TTR and thyroxine (T(4)) are correlated in the CSF, and whether CSF levels of Pb are associated with those of TTR, T(4), and/or retinol-binding protein (RBP). Eighty-two paired CSF and blood/serum samples were collected from patients undergoing clinical diagnosis of CSF chemistry. Results showed that the mean value of CSF concentrations for TTR was 3.33 +/- 1.60 microg/mg of CSF proteins (mean +/- SD, n = 82), for total T(4) (TT(4)) was 1.56 +/- 1.68 ng/mg (n = 82), for RBP was 0.34 +/- 0.19 microg/mg (n = 82), and for Pb was 0.53 +/- 0.69 microg/dl (n = 61 for those above the detection limit). Linear regression analyses revealed that CSF TTR levels were positively associated with those of CSF TT(4) (r = 0.33, p < 0.005). CSF TTR concentrations, however, were inversely associated with CSF Pb concentrations (r = -0.29, p < 0.05). There was an inverse, albeit weak, correlation between CSF TT(4) and CSF Pb concentrations (r = -0.22, p = 0.09). The concentrations of TTR, TT(4), and Pb in the CSF did not vary as the function of their levels in blood or serum, but RBP concentrations in the CSF did correlate to those of serum (r = 0.39, p < 0.0005). Unlike TTR, CSF RBP concentrations were not influenced by PB: These human data are consistent with our earlier observations in animals, which suggest that TTR is required for thyroxine transport in the CSF and that Pb exposure is likely associated with diminished TTR levels in the CSF.

Adolescent↗

PubMed2001

Municipal drinking water nitrate level and cancer risk in older women: the Iowa Women's Health Study.

Nitrate contamination of drinking water may increase cancer risk, because nitrate is endogenously reduced to nitrite and subsequent nitrosation reactions give rise to N-nitroso compounds; these compounds are highly carcinogenic and can act systemically. We analyzed cancer incidence in a cohort of 21,977 Iowa women who were 55-69 years of age at baseline in 1986 and had used the same water supply more than 10 years (87% > 20 years); 16,541 of these women were on a municipal supply, and the remainder used a private well. We assessed nitrate exposure from 1955 through 1988 using public databases for municipal water supplies in Iowa (quartile cutpoints: 0.36, 1.01, and 2.46 mg per liter nitrate-nitrogen). As no individual water consumption data were available, we assigned each woman an average level of exposure calculated on a community basis; no nitrate data were available for women using private wells. Cancer incidence (N = 3,150 cases) from 1986 through 1998 was determined by linkage to the Iowa Cancer Registry. For all cancers, there was no association with increasing nitrate in drinking water, nor were there clear and consistent associations for non-Hodgkin lymphoma; leukemia; melanoma; or cancers of the colon, breast, lung, pancreas, or kidney. There were positive associations for bladder cancer [relative risks (RRs) across nitrate quartiles = 1, 1.69, 1.10, and 2.83] and ovarian cancer (RR = 1, 1.52, 1.81, and 1.84), and inverse associations for uterine cancer (RR = 1, 0.86, 0.86, and 0.55) and rectal cancer (RR = 1, 0.72, 0.95, and 0.47) after adjustment for a variety of cancer risk/protective factors, agents that affect nitrosation (smoking, vitamin C, and vitamin E intake), dietary nitrate, and water source. Similar results were obtained when analyses were restricted to nitrate level in drinking water from 1955 through 1964. The positive association for bladder cancer is consistent with some previous data; the associations for ovarian, uterine, and rectal cancer were unexpected.

Age Factors↗

PubMed2001

Sulfation pharmacogenetics: SULT1A1 and SULT1A2 allele frequencies in Caucasian, Chinese and African-American subjects.

Sulfotransferase (SULT) enzymes catalyze the sulfate conjugation of drugs, other xenobiotics, neurotransmitters and hormones. The genes for SULT1A1 and SULT1A2 contain common genetic polymorphisms that are associated with individual variations in levels of enzyme activity as well as variations in biochemical and physical properties. We set out to compare the frequencies of common SULT1A1 and SULT1A2 alleles in Caucasian, Chinese and African-American subjects. Allele frequencies for SULT1A1*1, *2 and *3 in 242 Caucasian subjects were 0.656, 0.332 and 0.012, respectively. Frequencies of those same alleles were significantly different in 290 Chinese subjects: 0.914, 0.080 and 0.006, respectively, as were frequencies in 70 African-American subjects: 0.477, 0.294 and 0.229, respectively. Ethnic variation in allele frequencies was also observed for SULT1A2, with frequencies in Caucasian subjects for SULT1A2*1, *2 and *3 of 0.507, 0.389 and 0.104; frequencies in Chinese of 0.924 and 0.076 with no *3 alleles observed; and, finally, in African-Americans frequencies of 0.637, 0.249 and 0.114, respectively. We also found that SULT1A1*2 and SULT1A2*2, the most common variant alleles for these two genes, were in positive linkage disequilibrium in all three populations studied, with D' values of 0.776 in Caucasian (P < 0.001), 0.915 in Chinese (P < 0.001) and 0.864 in African-American subjects (P < 0.001). These observations represent a step towards determining the possible functional implications for individual variations in sulfate conjugation of common genetic polymorphisms for SULT1A1 and SULT1A2.

Adolescent↗

PubMed2001

Mechanisms of coronary angiogenesis in response to stretch: role of VEGF and TGF-beta.

To test the hypotheses that cyclic stretch of 1) cardiac myocytes produces factors that trigger angiogenic events in coronary microvascular endothelial cells (CMEC) and 2) CMEC enhances the expression of growth factors, cardiac myocytes and CMEC were subjected to cyclic stretch in a Flexercell Strain Unit. Vascular endothelial growth factor (VEGF) but not basic fibroblast growth factor mRNA and protein levels increased approximately twofold in myocytes after 1 h of stretch. CMEC DNA synthesis increased approximately twofold when conditioned medium from stretched myocytes or VEGF protein was added, and addition of VEGF neutralizing antibody blocked the increase. CMEC migration and tube formation increased with the addition of conditioned media but were markedly attenuated by VEGF neutralizing antibody. Myocyte transforming growth factor-beta [corrected] (TGF-beta) increased 2.5-fold after 1 h of stretch, and the addition of TGF-beta neutralizing antibodies inhibited the stretch-induced upregulation of VEGF. Stretch of CMEC increased VEGF mRNA in these cells (determined by Northern blot and RT-PCR) and increased the levels of VEGF protein (determined by ELISA analysis) in the conditioned media. Therefore, cyclic stretch of cardiac myocytes and CMEC appears to be an important primary stimulus for coronary angiogenesis through both paracrine and autocrine VEGF pathways. These data indicate that 1) CMEC DNA synthesis, migration, and tube formation are increased in response to VEGF secreted from stretched cardiac myocytes; 2) VEGF in CMEC subjected to stretch is upregulated and secreted; and 3) TGF-beta signaling may regulate VEGF expression in cardiac myocytes.

Animals↗

PubMed2001

Identification of the descriptor pharmacophores using variable selection QSAR: applications to database mining.

The pharmacophore concept is central to the rational drug design and discovery process. Traditionally, a pharmacophore is defined as a specific three-dimensional (3D) arrangement of chemical functional groups found in active molecules, which are characteristic of a certain pharmacological class of compounds. Herein, by analogy with 3D pharmacophores, a more general concept of descriptor pharmacophore is introduced. The descriptor pharmacophores are defined by the means of variable selection QSAR as a subset of molecular descriptors that afford the most statistically significant structure-activity correlation. The two variable selection QSAR methods developed in this laboratory are discussed; these include Genetic Algorithms--Partial Least Squares (GA-PLS) and K-Nearest Neighbors (KNN). Both methods employ multiple topological descriptors of chemical structures such as molecular connectivity indices or atom pairs (AP), and stochastic optimization algorithms to achieve a robust QSAR model, which is characterized by the highest value of cross-validated R2 (q2). By default, the descriptor pharmacophore represents an invariant selection of descriptor types however, descriptor values are generally different for different molecules. We demonstrate that chemical similarity searches using descriptor pharmacophores as opposed to using all descriptors afford more efficient mining of chemical databases or virtual libraries to discover compounds with a desired biological activity.

Algorithms↗

PubMed2001

Sulfotransferase 1A1 polymorphism, endogenous estrogen exposure, well-done meat intake, and breast cancer risk.

Sulfotransferase (SULT) 1A1 is involved in the inactivation of estrogens and bioactivation of heterocyclic amines and polycyclic aromatic hydrocarbons. A G--->A transition at codon 213 (CGC/Arg to CAC/His) of the SULT1A1 gene was reported recently, and individuals homozygous for the His allele have a substantially lower activity of this enzyme than those with other genotypes. We hypothesized that the His allele may be a risk factor for breast cancer, particularly among women who had risk factors related to higher endogenous estrogen exposure. This hypothesis was investigated in a case-control study conducted in a cohort of postmenopausal Iowa women who completed a mailed questionnaire in 1986 on lifestyle factors including information on major breast cancer risk factors. DNA samples and information related to well-done meat intake were obtained from breast cancer cases diagnosed between 1992 and 1994 and a random sample of cancer-free cohort members. Multivariate analysis was performed on data from 156 cases and 332 controls who donated a blood sample. The frequency of the His allele was 41.6% in cases and 34.1% in controls (P = 0.03), and the risk of breast cancer was increased with the number of His alleles (P for trend = 0.02). Compared with women with the Arg/Arg genotype, an 80% elevated risk was observed among women homozygous for the His allele (95% confidence interval, 1.0-3.2; P = 0.04). This positive association was more pronounced among women who drank alcohol and had a high body mass index, early age at menarche, and late age at menopause, factors related to high endogenous estrogen exposure, than among those who did not have these risk factors. The risk of breast cancer was elevated with increasing doneness level of red meat intake among women with the Arg/Arg genotype (P for trend, 0.01) or the Arg/His genotype (P for trend, 0.10), whereas this association was not evident for women with the His/His genotype. The results from this study suggest that homozygosity for the SULT1A1 His213 allele may be a risk factor for breast cancer, and its effect may be modified by the exposure level of endogenous estrogens and heterocyclic amines.

Age Distribution↗

PubMed2001

Epidemiological study of urinary 6beta-hydroxycortisol to cortisol ratios and breast cancer risk.

The ratio of urinary 6beta-hydroxycortisol:cortisol is a measure of the activity of cytochrome p450 3A4 (CYP3A4). CYP3A4 catalyzes the formation of the genotoxic estrogen, 16alpha-hydroxyestrone. It is also involved in the activation of many other mammary carcinogens, such as the polycyclic aromatic hydrocarbons and heterocyclic amines. We evaluated the association between urinary cortisol ratios and breast cancer risk in a subgroup of women who participated in a population-based case-control study in Shanghai. Overnight urine samples from 246 case-control pairs were assayed for 6beta-hydroxycortisol (6beta-OHC) to cortisol. The urine samples from all of the breast cancer patients were collected before any chemotherapy or radiotherapy. In-person interviews were conducted to obtain comprehensive information on dietary habits, reproductive history, and other lifestyle factors. The median levels of 6beta-OHC:cortisol ratios were 2.61 in cases and 2.16 in controls, a 20.8% difference (P < 0.001). The case-control difference was larger in women over 45 years of age (31.3% difference; P < 0.001) than younger women (6.0%; P = 0.45). After adjusting for confounding variables, the risks of breast cancer were increased from 1.0 (reference) to 1.6 [95% confidence interval (CI), 0.9-3.1], 2.2 (95% CI, 1.1-4.2), and 3.7 (95% CI, 1.9-7.4; P for trend, <0.001) with increasing levels of 6beta-OHC:cortisol ratios. The positive association was more pronounced among older women (>45 years) than among younger women (< or = 45 years). The adjusted odds ratios associated with the highest cortisol ratio were 6.0 (95%CI, 2.2-16.1) among older women and 2.2 (95%CI, 0.8-6.1) among younger women. The association of the 6beta-OHC:cortisol ratio was stronger among older women who had a high body mass index, late age at menopause, and early age at menarche (factors related to high endogenous estrogen exposure) than those who did not have these factors. These findings are consistent with the role of CYP3A4 in estrogen and carcinogen metabolism and suggest that high CYP3A4 activity may be a risk factor for breast cancer risk.

Adult↗

PubMed2001

Blood transfusions and risk of non-Hodgkin's lymphoma subtypes and chronic lymphocytic leukemia.

Allogeneic blood transfusion has been suggested as a risk factor for non-Hodgkin's lymphoma (NHL), possibly specific to certain NHL subtypes, or chronic lymphocytic leukemia (CLL). Self-reported transfusion history and risk of NHL subtypes and CLL were examined in a cohort of 37,934 older Iowa women, using data from a questionnaire mailed in 1986. Through 1997, 229 cases of NHL and 57 cases of CLL in the cohort were identified through linkage to the Iowa Surveillance, Epidemiology and End Results Cancer REGISTRY: Women who reported ever receiving a blood transfusion were at increased risk for all NHLs [age adjusted relative risk (RR), 1.6; 95% confidence interval (CI), 1.2-2.1). On the basis of the Working Formulation classification, blood transfusion was positively associated with low-grade NHL (RR, 2.7; 95% CI, 1.7-4.5) but not with intermediate-grade NHL (RR, 1.1; 95% CI, 0.7-1.6); there were only 8 cases of high-grade NHL. Blood transfusion was positively associated with follicular (RR, 2.8; 95% CI, 1.6-5.1) and small lymphocytic (RR, 3.4; 95% CI, 1.5-7.9) NHL subtypes but not with diffuse NHL (RR, 1.0; 95% CI, 0.7-1.5). There was also a positive association with CLL (RR, 1.7; 95% CI, 1.0-3.0). Finally, transfusion was associated with nodal (RR, 1.8; 95% CI, 1.3-2.5) but not extranodal (RR, 1.2; 95% CI, 0.7-2.1) NHL. Further adjustment for marital status, farm residence, diabetes, alcohol use, smoking, and red meat and fruit consumption did not alter these associations. In conclusion, prior blood transfusion was associated with NHL and CLL, and the strongest associations were seen for low-grade NHL, particularly follicular and small lymphocytic NHL.

Aged↗

PubMed2001

Soyfood intake during adolescence and subsequent risk of breast cancer among Chinese women.

Many experimental but few epidemiological studies have suggested that soyfoods and their constituents have cancer-inhibitory effects on breast cancer. No epidemiological study has evaluated the association of adolescent soyfood intake with the risk of breast cancer. To evaluate the effect of soyfood intake during adolescence, one of the periods that breast tissue is most sensitive to environmental stimuli, on subsequent risk of breast cancer, we analyzed data from a population-based case-control of 1459 breast cancer cases and 1556 age-matched controls (respective response rates were 91.1% and 90.3%). Information on dietary intake from ages 13-15 years was obtained by interview from all study participants and, in addition, from mothers of subjects less than 45 years of age (296 cases and 359 controls). Odds ratios (ORs) and 95% confidence intervals (CIs) derived from unconditional logistic models were used to measure soyfood intake and breast cancer risk. After adjustment for a variety of other risk factors, adolescent soyfood intake was inversely associated with risk, with ORs of 1.0 (reference), 0.75 (95% CI, 0.60-0.93), 0.69 (95% CI, 0.55-0.87), 0.69 (95% CI, 0.55-0.86), and 0.51 (95% CI, 0.40-0.65), respectively, for the lowest to highest quintiles of total soyfood intake (trend test, P < 0.001). The inverse association was observed for each of the soyfoods examined and existed for both pre- and postmenopausal women. Adolescent soyfood intakes reported by participants' mothers were also inversely associated with breast cancer risk (P for trend < 0.001), with an OR of 0.35 (95% CI, 0.21-0.60) for women in the highest soyfood intake group. Adjustment for rice and wheat products, the major energy source in the study population, and usual adult soyfood intake did not change the soyfood associations. Our study suggests that high soy intake during adolescence may reduce the risk of breast cancer in later life.

Adolescent↗

PubMed2001

[Effects of pesticide imidacloprid and its metabolites on soil respiration].

Soil respiration was measured using NaOH absorbing technique. Imidacloprid were applied to soil samples at concentration of 0, 10, 40, 100 micrograms.g-1, its hydrolysis and photolysis products were applied at 40 micrograms.g-1. The more significant effect at higher concentration of imidacloprid was observed. The effect of its hydrolysis product was minor than imidacloprid, but the photolysis products of 10 min have stronger effect, the effect decreased greatly in 30 min. Soil respiration recovered after 13 days. It showed that imidacloprid and its metabolites have little effect on soil microorganism.

Carbon Dioxide↗

PubMed2001

Adsorption of chloroacetanilide herbicides on soil (I). Structural influence of chloroacetanilide herbicide for their adsorption on soils and its components.

Adsorption of chloroacetanilide herbicide acetochlor, alachlor, metolachlor and propachlor on soils and soil components was determined, and the structural differences of these herbicides were used to explain the order of sorptivity. Adsorption isotherms for all herbicide-soil combinations conformed to the Freundlich equation, and Ki increased with increasing soil organic carbon content. Kd on soil humic acid was greater than that on clay, but association of humic acid with clay reduced the overall adsorption. On all soils and soil humic acids, herbicide adsorption decreased in the order: metolachlor > acetochlor > propachlor > alachlor. On Ca(2+)-montmorrilonite, the order changed to metolachlor > acetochlor > alachlor > propachlor. FT-IR spectra of herbicide-clay or herbicide-humic acid-clay mixtures showed that H-bonding and charge transfer were the primary interaction pathways between these compounds and the surface of clay or humic acids. The different moieties attached to 2-chloro-acetanilide and their unique arrangement may have influenced the binding mechanisms and thus the sorptivity of these herbicides. This study indicates that the structural difference of pesticides in the same classes may be used as a molecular probe to obtain a better understanding of sorption mechanisms of pesticides on soil.

Acetamides↗