Mediation of the relationship between phthalate exposure and semen quality by oxidative stress among 1034 reproductive-aged Chinese men.

BACKGROUND: Emerging evidence from animals indicates that oxidative stress plays a crucial role in the effects of phthalate exposure on male reproductive dysfunctions, which has never been thoroughly explored in humans. OBJECTIVE: To explore the potential mediating role of oxidative stress in the association of phthalate exposure with semen quality among 1034 Chinese men. METHOD: Repeated urine samples gathered from the male partners of sub-fertile couples were analyzed for 3 oxidative stress markers [8-hydroxy-2-deoxyguanosine (8-OHdG), 8-iso-prostaglandin F2α (8-isoPGF2α) and 4-hydroxy-2-nonenal-mercapturic acid (HNE-MA)], using a liquid chromatography-tandem mass spectrometry. Multivariate regression models were constructed to evaluate the associations of urinary oxidative stress markers with urinary phthalate metabolites and semen quality. We also explored the potential mediation effects by oxidative stress markers. RESULTS: Significantly positive dose-dependent relationships were observed between each individual phthalate metabolite and all analyzed oxidative stress markers (all p for trend<0.05), except for monoethyl phthalate (MEP) in relation to HNE-MA. Additionally, significantly or suggestively inverse dose-dependent relationships were exhibited between urinary 8-isoPGF2α and sperm concentration (p for trend = 0.05), and between urinary 8-OHdG and percent of normal sperm morphology (p for trend = 0.01). Mediation analysis showed that urinary 8-isoPGF2α suggestively mediated 12% of the inverse association between monobutyl phthalate (MBP) and sperm concentration, and that urinary 8-OHdG suggestively mediated 32% of the inverse association of MEP with percent of normal sperm morphology (both p < 0.10). CONCLUSIONS: Although further investigations are required, our results suggest that oxidative stress may play a mediating role in the effects of phthalate exposure on impaired semen quality.

The short-term effects of outdoor temperature on blood pressure among children and adolescents: finding from a large sample cross-sectional study in Suzhou, China.

Although several studies have demonstrated a short-term association between outdoor temperature and blood pressure (BP) among various adult groups, evidence among children and adolescents is lacking. One hundred ninety-four thousand one hundred four participants from 2016 Health Promotion Program for Children and Adolescents (HPPCA) were analyzed through generalized linear mixed-effects models to estimate the short-term effects of two outdoor temperature variables (average and minimum temperature) on participants' BP. Decreasing outdoor temperature was associated with significant increases in systolic BP (SBP), diastolic BP (DBP), and prevalence of hypertension during lag 0 through lag 6. Additionally, daily minimum temperature showed a more apparent association with participants' BP. The estimated increases (95% confidence interval) in SBP and DBP at lag 0 were 0.82 (0.72, 0.92) mmHg and 2.28 (2.20, 2.35) mmHg for a 1 °C decrease in daily minimum temperature, while those values were 0.11 (0.10, 0.12) mmHg and 0.25 (0.24, 0.26) mmHg for a 1 °C decrease in daily average temperature, respectively. The effects of temperature on BP were stronger among female, as well as those with young age and low body mass index. It demonstrated that short-term decreases in outdoor temperature were significantly associated with rises in BP among children and adolescents. This founding has some implications for clinical management and research of BP. Meanwhile, public health intervention should be designed to reduce the exposure to cold temperature for protecting children and adolescents' BP.

Association of phthalate exposure with anthropometric indices and blood pressure in first-grade children.

We aimed to assess the relationship of urine phthalate metabolite concentrations with anthropometric indices, and blood pressure in first-grade children. We detected 11 phthalate metabolites in urine and estimated anthropometric indices, including skinfold measurements, waist circumference (WC), and body mass index (BMI) in 276 children aged 6-8 years. Multivariate linear regression models were used to assess the associations between urinary phthalate metabolite levels, and anthropometric and blood pressure indices in a gender-specific manner. In boys, a 1-ng/mL increase in monobenzyl phthalate (MBzP) concentration was associated with a 0.027-cm decrease in the skinfold measurement (95% confidence interval [CI], - 0.053 to 0.001), whereas a 1-ng/mL increase in mono-ethyl-phthalate (MEP) concentration was associated with a 0.016-mm Hg decrease in systolic blood pressure (95% CI, - 0.031 to 0.001). MBzP, mono-(2-ethyl-5-carboxypentyl) phthalate (MECPP), and MEOHP concentrations were also inversely associated with WC. However, in girls, MEP concentrations were positively associated with chest measurements, but were inversely associated with WC. A 1-ng/mL increase in monomethyl phthalate concentrations was associated with a 0.039-cm increase in skinfold measurements (95% CI, 0.002 to 0.076), whereas a 1-ng/mL increase in MECPP concentrations was associated with a 0.050 cm decrease in skinfold measurements (95% CI, - 0.095 to - 0.005). In this exploratory, cross-sectional analysis, we identified various interesting associations between different phthalate metabolite levels and anthropometric indices, which suggest that some of phthalate metabolite should be considered in addition to the prevalence rates of overweight and obesity.

Effects of resting heart rate on blood pressure and hypertension in Chinese children: findings from blood pressure surveillance program.

The purpose of this study was to analyze the association between resting heart rate (RHR) and prevalence of hypertension in Chinese children and to identify if this association was mediated by body mass index (BMI). The data of 5445 children who participated in the Blood Pressure Surveillance Program (2011-2017) were analyzed in this study. Children were divided into four groups according to quartiles of RHR in boys and girls, respectively. Compared to those in the first quartile, boys and girls in the fourth quartile were 3.06 (95% CI 2.12, 4.41) and 4.94 (95% CI 3.21, 7.61) times more likely to have hypertension, respectively. Meanwhile, every 10 beats per minute (bpm) increase in RHR was associated with a 41% (95% CI 1.27, 1.56) and 66% (95% CI 1.49, 1.85) greater risk of hypertension in boys and girls, respectively. There were no significant interactions between RHR and BMI on the prevalence of hypertension. This study confirms the existence of a relationship between elevated RHR and increased risk of hypertension in children, independent of BMI. An elevated RHR could be considered as a risk factor for the risk assessment of hypertension, no matter from a clinical setting or a public health perspective.

Dose-response relationship between blood lead levels and hematological parameters in children from central China.

BACKGROUND: Lead is a heavy metal that can affect the human hematological system. However, reports are limited on the dose-response relationship between blood lead levels (BLLs) and hematological parameters in children. This study aimed to explore the dose-response relationship between BLLs and hematological measurements among children in China. METHODS: A cross-sectional design was used. A total of 743 children aged 5-8 years were recruited from two counties in central China. The BLLs and blood levels of iron, zinc, and calcium were determined, and hematological parameters were measured. RESULTS: All hematological measurements and BLLs were logarithm-transformed to ensure a normal distribution. The geometric mean of the BLLs of all children was 82.4 µg/L. Forty-one percent of the children had BLLs ≥ 100 µg/L. The lead-poisoning percentages of the children were significantly associated with gender, age, district of residence, and environmental lead exposure level. Multivariate linear regression analyses showed no significant linear correlation between BLL and each hematological parameter among the children with BLLs ≥ 100 µg/L. The analyses also revealed a small increase in red blood cell count (RBC) with increasing BLLs in the BLLs < 100 µg/L group (ß = 0.03, P =  0.048). A negative association was noted between BLLs and blood platelet (PLT) count in the children with BLLs < 100 µg/L (ß = -0.90, P < 0.001). Logistic regression analyses showed that BLLs were significantly associated with decreased hemoglobin (Hb) levels, RBC counts, PLT counts and mean corpuscular hemoglobin (MCH) after adjusting for potential confounders. Such analyses also revealed a dose-response relationship between the BLLs and hematological parameters (Hb level, RBC count, and PLT count). The children with BLLs ≥ 100 µg/L were 2.72, 2.51, and 3.76 times more likely to achieve decreased RBC counts, Hb levels and PLT counts, respectively, compared to those with BLLs < 100 µg/L. Compared with children with BLLs < 100 µg/L, those with BLLs ≥ 100 µg/L were 3.16 and 4.38 times more likely to show decreased Hb levels and PLT counts respectively in the high-level lead-exposure group and 4.33 times more likely to achieve a decreased PLT count in the low-level lead-exposure group. The individuals with BLLs of the highest quartile were 3.65, 5.87, and 29.23 times more likely to exhibit decreased Hb levels, RBC counts, and PLT counts, respectively, than the children with BLLs of the lowest quartile. CONCLUSION: Our findings suggested a negative association between BLLs and hematological indicators (Hb level, RBC count, PLT count and MCH). A strong negative, non-linear dose-response relationship was also showed between BLLs and hematological parameters (Hb level, RBC count, and PLT count).

Assessment of heavy metal pollution and human health risks in urban soils around an electronics manufacturing facility.

Heavy metal pollution has pervaded many parts of the world, especially in developing countries. The purpose of this study was to determine the concentrations and health risks of heavy metals in urban soils around an electronics manufacturing site in the Hubei Province of China. Soils samples were collected from commercial, roadside, farmland, and residential areas around the electronics manufacturing facility. A total of 136 topsoil samples were collected, and these samples were analyzed for Cr, Cu, Zn, As, Cd, Ni, and Pb. The geoaccumulation index (Igeo), pollution index (PI), and potential ecological risk index (PER) were calculated to assess the soil pollution levels. The hazard index (HI) was used to assess the human health risks posed by the presence of heavy metals. The total concentrations of the seven congeners (∑metals) ranged from 3738.86 to 5173.25mgkg-1, and the concentrations were highest in the commercial area followed (in decreasing order) by the roadside, farmland, and residential areas. The HI for children and adults descended in the order of Cr>As>Pb>Cd>Cu>Ni>Zn. The carcinogenic risks of two metals, namely, Cr and As, for children and adults were higher than 10-4, and children faced greater health risks.

Development and validation of two prognostic nomograms for predicting survival in patients with non-small cell and small cell lung cancer.

PURPOSE: This study aimed to construct two prognostic nomograms to predict survival in patients with non-small-cell lung cancer (NSCLC) and small-cell lung cancer (SCLC) using a novel set of clinical parameters. PATIENTS AND METHODS: Two nomograms were developed, using a retrospective analysis of 5384 NSCLC and 647 SCLC patients seen during a 10-year period at Xiang Ya Affiliated Cancer Hospital (Changsha, China). The patients were randomly divided into training and validation cohorts. Univariate and multivariate analyses were used to identify the prognostic factors needed to establish nomograms for the training cohort. The model was internally validated via bootstrap resampling and externally certified using the validation cohort. Predictive accuracy and discriminatory capability were estimated using concordance index (C-index), calibration curves, and risk group stratification. RESULTS: The largest contributor to overall survival (OS) prognosis in the NSCLC nomogram was the therapeutic regimen and diagnostic method parameters, and in the SCLC nomogram was the therapeutic regimen and health insurance plan parameters. Calibration curves for the nomogram prediction and the actual observation were in optimal agreement for the 3-year OS and acceptable agreement for the 5-year OS in both training datasets. The C-index was higher for the NSCLC cohort nomogram than for the TNM staging system (0.67 vs. 0.64, P = 0.01) and higher for the SCLC nomogram than for the clinical staging system (limited vs. extensive) (0.60 vs. 0.53, P = 0.12). CONCLUSION: Treatment regimen parameter made the largest contribution to OS prognosis in both nomograms, and these nomograms might provide clinicians and patients a simple tool that improves their ability to accurately estimate survival based on individual patient parameters rather than using an averaged predefined treatment regimen.

Association of elevated resting pulse rate with increased risk of hypertension development in children: A prospective study in Suzhou, China.

BACKGROUND: Elevated resting heart rate (RHR) or resting pulse rate (RPR) is associated with increased risk of hypertension development. However, information is limited to adults. The purpose of this study is to analyze this association among Chinese children in a prospective design. METHODS: A total of 4861 children who participated in the Blood Pressure Surveillance Program (2011-2017) were selected in this research. To investigate the association between RPR and hypertension development, children were divided into 4 groups according to the quartiles of RPR at baseline. Odds ratios (ORs) with 95% confidence intervals (CIs) were calculated using logistic regression model. RESULTS: Over a mean follow-up of 3.0 ±â€Š0.1 years, there were 384 cases of incident hypertension. Compared to boys and girls in the 1st quartile, those in the 4th quartile were 1.73 (95% CI 1.13, 2.65), 2.22 (95% CI 1.43, 3.45) times more likely to have hypertension, respectively. Every 10 bpm increase in RPR was associated with a 26% greater risk of hypertension development in boys (OR: 1.26; 95% CI 1.10, 1.44), while this risk was 1.28 (95% CI 1.13, 1.44) in girls. Baseline blood pressure (BP) and body mass index (BMI) did not have significant interactions with RPR on risk of hypertension development. CONCLUSION: This study confirms the relationship between elevated RPR and increased risk of hypertension development in children, independent of confounders including baseline BP and BMI. An elevated RPR could be considered as a risk factor for the assessment of hypertension, no matter from a clinical setting or a public health perspective.

Phthalate levels and related factors in children aged 6-12 years.

Although previous studies showed that children are widely exposed to phthalates, the sources of phthalate exposure for school-aged children in China are not well understood. This study aimed to assess phthalate metabolite levels and explore the factors influencing exposure in children. We collected demographic data and biological samples from 336 children aged 6-12 years. We calculated urinary concentrations of 14 mono-phthalate metabolites and conducted chi-square (χ2) tests and logistic regression analysis to determine the variables associated with phthalate levels. Mono-n-butyl phthalate (MnBP) and mono-(2-ethyl-5-hydroxyhexyl) phthalate (MEHHP) were the most abundant urinary phthalate metabolites. In addition, housing type, decorating materials in the home, and frequency of canned food consumption were associated with exposure to low molecular weight phthalates. Water source, duration of time spent playing with toys, residential area, and frequency of canned food consumption were associated with exposure to high molecular weight phthalates. Based on these results, potential strategies to reduce exposure to phthalates include avoiding plastic food containers and chemical fragrances as well as eating fewer processed foods, especially canned foods, and foods in plastic packaging.

Exposure to phthalates in children aged 5-7years: Associations with thyroid function and insulin-like growth factors.

This study aimed to evaluate the associations between phthalate concentrations and thyroid function in preschool children. We collected demographic data and biological samples from 216 children aged 5-7years. We calculated urinary concentrations of eight mono-phthalate metabolites (mPAEs) separately for children from urban and rural areas and investigated their associations with thyroid function and growth hormones. mPAE concentrations were higher in children from the urban area than in those from the rural area, and most mPAEs were positively associated with free triiodothyronine and free thyroxine. The insulin-like growth factor 1 (IGF-1) concentration decreased 0.082ng/mL (95% confidence interval [CI]: -1.34, -0.113) with each 1ng/mL increase in monomethyl phthalate (MMP) and 0.132ng/mL (95% CI: -0.209, -0.055) with each 1ng/mL increase in mono-n-butyl phthalate. The insulin-like growth factor binding protein 3 concentration decreased by 0.01mg/L (95% CI: -0.001, -0.000) or 0.01mg/L (95% CI: -0.003, -0.000) with each 1ng/mL increase in MMP or monoethyl phthalate, respectively. Exposure to some phthalates at 5-7years of age might interfere with thyroid hormones and growth.

Relation of body mass index (BMI) to the prevalence of hypertension in children: A 3years' school-based prospective study in Suzhou, China.

BACKGROUND: The prevalence of hypertension has been increasing in children and adolescents in China, which is considered to be accompanied with the epidemic of childhood overweight and obesity, but limited prospective studies have investigated the effect of body mass index (BMI) change on blood pressure among children, especially in China. METHODS: This school-based prospective study compared the blood pressure and prevalence of hypertension in students with different patterns of change in BMI between two periods (childhood and adolescence). 5465 children were followed-up since 2011(childhood) in Suzhou, China and had weight, height and blood pressure measured in 2011(childhood) and 2014(adolescence). RESULTS: Those who changed from being overweight in childhood to having normal BMI in adolescence had similar mean blood pressures to those who had a normal BMI at both two periods. In contrast, those who were overweight at both two periods or who had a normal BMI in childhood and were overweight in adolescence had higher blood pressure in adolescence than those who had a normal BMI at both two periods. Compared with students who had a normal BMI at both periods, those with combination of abnormal BMI in childhood and adolescence have higher ORs of hypertension (4.83 in boys, 3.44 in girls and 3.73 in total). CONCLUSION: These results suggest that obesity is a key determinant of blood pressure during childhood, and weight reduction may have important beneficial effects on blood pressure.

Analysis of phthalate esters in soils near an electronics manufacturing facility and from a non-industrialized area by gas purge microsyringe extraction and gas chromatography.

Here, a novel technique is described for the extraction and quantitative determination of six phthalate esters (PAEs) from soils by gas purge microsyringe extraction and gas chromatography. Recovery of PAEs ranged from 81.4% to 120.3%, and the relative standard deviation (n=6) ranged from 5.3% to 10.5%. Soil samples were collected from roadsides, farmlands, residential areas, and non-cultivated areas in a non-industrialized region, and from the same land-use types within 1 km of an electronics manufacturing facility (n=142). Total PAEs varied from 2.21 to 157.62 mg kg(-1) in non-industrialized areas and from 8.63 to 171.64 mg kg(-1) in the electronics manufacturing area. PAE concentrations in the non-industrialized area were highest in farmland, followed (in decreasing order) by roadsides, residential areas, and non-cultivated soil. In the electronics manufacturing area, PAE concentrations were highest in roadside soils, followed by residential areas, farmland, and non-cultivated soils. Concentrations of dimethyl phthalate (DMP), diethyl phthalate (DEP), and di-n-butyl phthalate (DnBP) differed significantly (P<0.01) between the industrial and non-industrialized areas. Principal component analysis indicated that the strongest explanatory factor was related to DMP and DnBP in non-industrialized soils and to butyl benzyl phthalate (BBP) and DMP in soils near the electronics manufacturing facility. Congener-specific analysis confirmed that diethylhexyl phthalate (DEHP) was a predictive indication both in the non-industrialized area (r(2)=0.944, P<0.01) and the industrialized area (r(2)=0.860, P<0.01). The higher PAE contents in soils near the electronics manufacturing facility are of concern, considering the large quantities of electronic wastes generated with ongoing industrialization.

Benchmark dose estimation for cadmium-induced renal tubular damage among environmental cadmium-exposed women aged 35-54 years in two counties of China.

BACKGROUND: A number of factors, including gender, age, smoking habits, and occupational exposure, affect the levels of urinary cadmium. Few studies have considered these influences when calculating the benchmark dose (BMD) of cadmium. In the present study, we aimed to calculate BMDs and their 95% lower confidence bounds (BMDLs) for cadmium-induced renal tubular effects in an age-specific population in south-central China. METHODS: In this study, urinary cadmium, ß2-microglobulin, and N-acetyl-ß-D-glucosaminidase levels were measured in morning urine samples from 490 randomly selected non-smoking women aged 35-54 years. Participants were selected using stratified cluster sampling in two counties (counties A and B) in China. Multiple regression and logistic regression analyses were used to investigate the dose-response relationship between urinary cadmium levels and tubular effects. BMDs/BMDLs corresponding to an additional risk (benchmark response) of 5% and 10% were calculated with assumed cut-off values of the 84th and 90th percentile of urinary ß2-microglobulin and N-acetyl-ß-D-glucosaminidase levels of the controls. RESULTS: Urinary levels of ß2-microglobulin and N-acetyl-ß-D-glucosaminidase increased significantly with increasing levels of urinary cadmium. Age was not associated with urinary cadmium levels, possibly because of the narrow age range included in this study. Based on urinary ß2-microglobulin and N-acetyl-ß-D-glucosaminidase, BMDs and BMDLs of urinary cadmium ranged from 2.08 to 3.80 (1.41-2.18) µg/g cr for subjects in county A and from 0.99 to 3.34 (0.74-1.91) µg/g cr for those in county B. The predetermined benchmark response of 0.05 and the 90th percentiles of urinary ß2-microglobulin and N-acetyl-ß-D-glucosaminidase levels of the subjects not exposed to cadmium (i.e., the control group) served as cut-off values. CONCLUSIONS: The obtained BMDs of urinary cadmium were similar to the reference point of 1 µg/g cr, as suggested by the European Food Safety Authority, indicating that cadmium exposure must be reduced to protect human health.

Surveillance of pathogens causing gastroenteritis and characterization of norovirus and sapovirus strains in Shenzhen, China, during 2011.

Viral gastroenteritis is one of the most common diseases in humans, and it is primarily caused by rotaviruses (RVs), astroviruses (AstVs), adenoviruses (AdVs), noroviruses (NoVs), and sapoviruses (SaVs). In this study, we determined the distribution of viral gastroenteritis and human calicivirus (HuCVs) in acute gastroenteritis patients in Shenzhen, China, during 2011. Real-time RT-PCR was used to detect norovirus (NoV), group A rotavirus (RV), adenovirus (AdV), and astrovirus (AstV). From a total of 983 fecal samples, NoV was detected in 210 (21.4 %); RoV in 173 (17.6 %); AstV in 10 (1.0 %); and AdV in 15 (1.5 %). Mixed infections involving two NoVs were found in 21 of the 387 pathogen-positive stool specimens. NoV and SaV genotypes were further tested using RT-PCRs and molecular typing and phylogenetic analysis were then performed based on the ORF1-ORF2 region for NoV and a conserved nucleotide sequence in the capsid gene for SaV. Of the 68 typed strains that were sequenced and genotyped, five were NoV G1 (7.5 %) and 63 were NoV GII (96.6 %). GII strains were clustered into five genotypes, including GII.4 (65.1 %; 36 GII.4 2006b and five GII.4 New Orleans), GII.3 (28.6 %), GII.2 (3.2 %), GII.6 (1.6 %), and GII.1 (1.6 %). While all fecal specimens were tested for SaVs, 15 (1.5 %) were positive, and of these, 12 isolates belonged to G1.2, and the remaining three SaV strains belonged to the SaV GII genogroup. Although various HuCVs were detected in acute gastroenteritis patients, NoV GII.4 2006b was more prevalent than the other HuCVs.

Application of BMD approach to identify thresholds of cadmium-induced renal effect among 35 to 55 year-old women in two cadmium polluted counties in China.

BACKGROUND: Cadmium (Cd) is a heavy metal that can cause renal tubular dysfunction in humans. Women are among the high-risk group for Cd health effects. Determining the thresholds of Cd-induced renal effects is important. Thus, in this article, we aimed to identify the benchmark dose (BMD) and its low limit (BMDL) levels as the Cd thresholds for Chinese women. METHODS: Epidemiologic investigation was performed in county A and county B to obtain data on Cd exposure and its renal effect on respondents. Levels of Cd (UCd), ß2-microglobulin (UB2M), and N-acetyl-ß-D-glucosaminidase (UNAG) were measured in morning urine samples. The BMD approach was mainly performed. RESULTS: Results of the BMD approach were similar whether the method was conducted for the two sets of data (collected in CA and CB, respectively) separately or cooperatively. The BMD/BMDL values of UCd for all subjects were 1.07/0.44 and 2.12/0.53 µg/g cr based on UB2M and UNAG, respectively, given a predetermined BMR of 0.05. CONCLUSIONS: The presented thresholds of Cd-induced renal effects (i.e., the BMDLs of UCd) are close to the counterpart values reported in Japan, Sweden and Belgium.

Molecular identification and analysis of human enteroviruses isolated from healthy children in Shenzhen, China from 2010 to 2011.

OBJECTIVE: To determine the prevalence and distribution of human enteroviruses (HEVs) among healthy children in Shenzhen, China. METHOD: Clinical specimens were obtained from 320 healthy children under 5 years old in Shenzhen, China from 2010 to 2011. The specimens were evaluated using real-time PCR and cell cultures. The positive specimens were further tested using reverse transcription-seminested PCR (RT-snPCR). Molecular typing and phylogenetic analysis were based on the sequence determined. RESULTS: Among the 320 samples, 34 were tested positive for HEVs (10.6%) and 22 different serotypes were identified using RT-snPCR. PV1 and PV2 were also detected. The predominant serotype observed was EV71 (17.6%), followed by CV-B4 (14.7%). HEV-B was detected most frequently, with an overall prevalence of 47.1%. HEV-A and HEV-C were found in 32.3% and 20.6% of the samples, respectively. No HEV-D was identified. Molecular phylogeny indicated that all EV71 strains were of C4 genotype. CONCLUSION: Although a variety of HEVs was detected in healthy children, HEV-B was relatively more prevalent than other HEV species. Considering HEV-A is more prevalent than HEV-B among patients with hand-foot-mouth disease, additional long-term surveillance of HEV is warranted in both asymptomatic and symptomatic populations.

Effects of exposure to low-level lead on spatial learning and memory and the expression of mGluR1, NMDA receptor in different developmental stages of rats.

The effect of different periods of lead exposure on deficits of learning and memory is still unclear. In this study, we conduct in vivo experiment to investigate the critical stages when lead induced neurotoxicity in rats and its underlying mechanisms in some critical stages. Rats were exposed to 0.2% mg/ml lead acetate solution via drinking water during gestation, lactation and ablactation periods. Behavior deficits were found in gestation and lactation. N-Methyl-d-aspartate (NMDA) receptor subunit 2A (NR2A) increased during gestation both in hippocampus and cerebral cortex compared to the control group; in all treatment groups NR2B decreased in hippocampus and in cerebral cortex during the lactation period. Meanwhile, in hippocampus metabotropic glutamate receptor 1 (mGluR1) decreased during gestation and lactation periods but increased during the ablactation period. These observations suggest that exposure to lead in gestation and lactation periods could cause neurobehavioral deficits which extend to adulthood, and lactation was a more sensitive period for lead exposure. Furthermore, the abnormal expression of NMDA receptor 2 (NMDAR 2) subunits and mGluR1 are likely to be associated with the impairment.

delta-Aminolevulinic acid dehydratase activity, urinary delta-aminolevulinic acid concentration and zinc protoporphyrin level among people with low level of lead exposure.

To evaluate the relationship of delta-aminolevulinic acid dehydratase (ALAD) activity, urinary delta-aminolevulinic acid (ALAU) level and blood zinc protoporphyrin (ZPP) concentration to low blood lead (PbB) levels, these biomarkers were determined for all subjects enrolled from a rural area of southeast China where people had low levels of exposure to lead. The mean values of PbB, ALAD, ALAU and ZPP were 67.11 microg/L (SD: 1.654, range: 10.90-514.04), 339.66 nmol ml(-1)h(-1) (1.419, 78.33-793.13), 20.64 microg/L (1.603, 2.00-326.00), and 0.14 micromol/L (3.437, 0.01-2.26), respectively. ALAD was inversely associated with low levels of PbB. ZPP was inversely related to low levels of PbB but positively related to relatively higher levels of PbB. Alcohol drinking contributed to low ALAD in men. Women had higher ZPP than men. ALAU had no significant association with PbB. In conclusion, ALAD possibly has a non-linear relation with low to moderate levels of PbB. At moderate levels of PbB, ZPP increases with increasing levels of PbB. ALAU is not suitable as an indicator for low levels of lead exposure.

Determination of trace tetracycline antibiotics in foodstuffs by liquid chromatography-tandem mass spectrometry coupled with selective molecular-imprinted solid-phase extraction.

A rapid, specific, and sensitive method has been developed using molecularly imprinted polymers (MIPs) as solid-phase extraction sorbents for extraction of trace tetracycline antibiotics (TCs) in foodstuffs. MIPs were prepared by precipitation polymerization using tetracycline as the template. Under the optimal condition, the imprinting factors for MIPs were 4.1 (oxytetracycline), 7.0 (tetracycline), 7.4 (chlortetracycline), 7.7 (doxycycline), respectively. Furthermore, the performance of MIPs as solid-phase extraction sorbents was evaluated and high extraction efficiency of molecularly imprinted solid-phase extraction (MISPE) procedure was demonstrated. Compared with commercial sorbents, MISPE gave a better cleanup efficiency than C18 cartridge and a higher recovery than Oasis HLB cartridge. Finally, the method of liquid chromatography-tandem mass spectrometry coupled with molecular-imprinted solid-phase extraction was validated in real samples including lobster, duck, honey, and egg. The spiked recoveries of TCs ranged from 94.51% to 103.0%. The limits of detection were in the range of 0.1-0.3 microg kg(-1).

[Introduction on a forecasting model for infectious disease incidence rate based on radial basis function network].

It is important to forecast incidence rates of infectious disease for the development of a better program on its prevention and control. Since the incidence rate of infectious disease is influenced by multiple factors, and the action mechanisms of these factors are usually unable to be described with accurate mathematical linguistic forms, the radial basis function (RBF) neural network is introduced to solve the nonlinear approximation issues and to predict incidence rates of infectious disease. The forecasting model is constructed under data from hepatitis B monthly incidence rate reports from 1991-2002. After learning and training on the basic concepts of the network, simulation experiments are completed, and then the incidence rates from Jan. 2003-Jun. 2003 forecasted by the established model. Through comparing with the actual incidence rate, the reliability of the model is evaluated. When comparing with ARIMA model, RBF network model seems to be more effective and feasible for predicting the incidence rates of infectious disease, observed in the short term.