Quantification of Cross-Contamination of Campylobacter jejuni during Food Preparation in a Model Kitchen in China.

ABSTRACT: Numerous outbreak investigations and case-control studies of campylobacteriosis have provided evidence that handling Campylobacter-contaminated chicken products is a high risk factor for infection and illness. In this study, the cross-contamination and transfer rates of Campylobacter jejuni from chicken to ready-to-eat food were determined in various food handling scenarios. Skinless raw chicken breasts were artificially contaminated with C. jejuni and diced on cutting boards of three different materials. Whether cold water, cold water with detergent, or hot water was used, statistically significant differences were found between the transfer rates of C. jejuni to unwashed and washed cutting boards or hands, respectively. When both kitchen knife and cutting board were reused after dicing the artificially contaminated chicken, the transfer rates of C. jejuni to cucumber cut on bamboo, wooden, and plastic cutting boards were 16.28, 12.82, and 5.32%, respectively. The transfer rates from chicken to bread, a large lift-up water faucet handle, and a small twist faucet handle via unwashed hands were 0.49, 4.64, and 3.14%, respectively. This research provides scientific evidence that various types of contaminated kitchenware and cook's hands are vital potential vehicles for the cross-contamination of Campylobacter from raw chicken to ready-to-eat food and emphasizes the importance of timely and proper cleaning to prevent cross-contamination during food handling; therefore, high-quality consumer education to reduce the risk of foodborne infection is urgent and necessary.

Prenatal Stress Impairs Postnatal Learning and Memory Development via Disturbance of the cGMP-PKG Pathway and Oxidative Phosphorylation in the Hippocampus of Rats.

Clinical and animal studies have found that prenatal stress can lead to pathological changes in embryos and fetuses. However, the mechanisms through which this occurs have not been made clear. In the present study, pregnant rats were subjected to chronic psychological stress during gestational days using an improved communication box system, and the changes in behavioral performance and proteins in the hippocampus of offspring were analyzed. It was found that prenatal stress caused postnatal growth retardation and impairment in spatial learning and memory. Furthermore, in isobaric tags for relative and absolute quantitation-based proteomics analyses, 158 significantly differentially expressed proteins (DEPs) were found between the two groups. Further analyses showed that these DEPs are involved in different molecular function categories and participate in several biological processes, such as energy metabolism, learning or memory, and synaptic plasticity. Moreover, the enrichment of pathways showed that the learning and memory impairment was primarily connected with the cyclic guanosine monophosphate-protein kinase G (cGMP-PKG) pathway and oxidative phosphorylation. At the same time, the cGMP level and the expression of PKG protein were significantly decreased, and the neuronal mitochondria appeared to have a swollen and irregular shape in the hippocampus of offspring of stressed rats. These results suggest that the chronic psychological stress that pregnant rats were subjected to during gestational days may have impaired the spatial learning and memory of offspring. This affected the hippocampal oxidative phosphorylation and inhibited the cGMP-PKG pathway.

Risk assessment of dietary exposure to aluminium in the Chinese population.

In order to address the issue of excessive intake of aluminium (Al) from Al-containing food additives in the Chinese diet, this study conducted a dietary exposure assessment of Al in the general population based on the national surveillance data of Al content in foods and national food consumption data. It was found that the mean dietary exposure of the whole Chinese population to Al from Al-containing food additives was 1.795 mg kg‒1 bw week‒1, not exceeding the PTWI, while high dietary exposures (e.g., 97.5th percentile) to Al were 7.660 and 2.103-2.903 mg kg‒1 bw week‒1 for children, respectively, both exceeding the PTWI. It was found that the dietary exposure to Al for 32.5% of the total Chinese population and 42.6% of children aged 4-6 years exceeded the PTWI. Wheat flour and wheat-based products are the main source of dietary A l exposure (85% of the total intake); and puffed foods are the major source of Al intake for children. These findings suggested that consumption of Al-containing food additives could be a health concern for consumers with high food consumption (97.5th percentile) and children under the age of 14 years.

The Survey of Cronobacter spp. (formerly Enterbacter sakazakii) in Infant and Follow-up Powdered Formula in China in 2012.

OBJECTIVE: To determine Cronobacter spp. contamination in infant and follow-up powdered formula in China. METHODS: All of 2282 samples were collected from the retail markets in China from January 2012 to December 2012, and analyzed for Cronobacter spp. by the Chinese National Food Safety Standard. Characterization of the isolates was analyzed by pulsed-field gel electrophoresis (PFGE) with XbaI and SpeI restriction enzymes. RESULTS: Cronobacter spp. strains were isolated from 25 samples, and the positive rates in infant powdered formulas and follow-up powdered formulas were 0.90% (10/1011) and 1.18% (15/1271), respectively. Analysis of variable data regarding different purchasing store formats, seasonality, and production locations as well as comparison of infant versus follow-up formulas did not reveal statistically significant factors. During the sampling period, one of six surveillance zones did exhibit a statistically significant trend towards higher positive rate. PFGE characterization of Cronobacter spp. to elucidate genetic diversity revealed only three pairs of Cronobacter spp. out of 25 having the same PFGE patterns. CONCLUSION: The current investigation indicated a lower positive rate of Cronobacter spp. in the powdered formula in China. This evidence suggested contamination originating from multiple different sources during the manufacturing process.

Hypomethylation of serum blood clot DNA, but not plasma EDTA-blood cell pellet DNA, from vitamin B12-deficient subjects.

Vitamin B12, a co-factor in methyl-group transfer, is important in maintaining DNA (deoxycytidine) methylation. Using two independent assays we examined the effect of vitamin B12-deficiency (plasma vitamin B12<148 pmol/L) on DNA methylation in women of childbearing age. Coagulated blood clot DNA from vitamin B12-deficient women had significantly (p<0.001) lower percentage deoxycytidine methylation (3.23±0.66%; n = 248) and greater [3 H]methyl-acceptance (42,859±9,699 cpm; n = 17) than DNA from B12-replete women (4.44±0.18%; n = 128 and 26,049±2,814 cpm; n = 11) [correlation between assays: r = -0.8538; p<0.001; n = 28]. In contrast, uncoagulated EDTA-blood cell pellet DNA from vitamin B12-deficient and B12-replete women exhibited similar percentage methylation (4.45±0.15%; n = 77 vs. 4.47±0.15%; n = 47) and [3 H]methyl-acceptance (27,378±4,094 cpm; n = 17 vs. 26,610±2,292 cpm; n = 11). Therefore, in simultaneously collected paired blood samples, vitamin B12-deficiency was associated with decreased DNA methylation only in coagulated samples. These findings highlight the importance of sample collection methods in epigenetic studies, and the potential impact biological processes can have on DNA methylation during collection.

Genomic DNA methylation changes in response to folic acid supplementation in a population-based intervention study among women of reproductive age.

Folate is a source of one-carbons necessary for DNA methylation, a critical epigenetic modification necessary for genomic structure and function. The use of supplemental folic acid is widespread however; the potential influence on DNA methylation is unclear. We measured global DNA methylation using DNA extracted from samples from a population-based, double-blind randomized trial of folic acid supplementation (100, 400, 4000 µg per day) taken for 6 months; including a 3 month post-supplementation sample. We observed no changes in global DNA methylation in response to up to 4,000 µg/day for 6 months supplementation in DNA extracted from uncoagulated blood (approximates circulating blood). However, when DNA methylation was determined in coagulated samples from the same individuals at the same time, significant time, dose, and MTHFR genotype-dependent changes were observed. The baseline level of DNA methylation was the same for uncoagulated and coagulated samples; marked differences between sample types were observed only after intervention. In DNA from coagulated blood, DNA methylation decreased (-14%; P<0.001) after 1 month of supplementation and 3 months after supplement withdrawal, methylation decreased an additional 23% (P<0.001) with significant variation among individuals (max+17%; min-94%). Decreases in methylation of ≥25% (vs. <25%) after discontinuation of supplementation were strongly associated with genotype: MTHFR CC vs. TT (adjusted odds ratio [aOR] 12.9, 95%CI 6.4, 26.0). The unexpected difference in DNA methylation between DNA extracted from coagulated and uncoagulated samples in response to folic acid supplementation is an important finding for evaluating use of folic acid and investigating the potential effects of folic acid supplementation on coagulation.

MTHFR 677C->T genotype is associated with folate and homocysteine concentrations in a large, population-based, double-blind trial of folic acid supplementation.

BACKGROUND: The methylenetetrahydrofolate reductase (MTHFR) genotype is associated with modification of disease and risk of neural tube defects. Plasma and red blood cell (RBC) folate and plasma homocysteine concentrations change in response to daily intakes of folic acid supplements, but no large-scale or population-based randomized trials have examined whether the MTHFR genotype modifies the observed response. OBJECTIVE: We sought to determine whether the MTHFR 677C→T genotype modifies the response to folic acid supplementation during and 3 mo after discontinuation of supplementation. DESIGN: Northern Chinese women of childbearing age were enrolled in a 6-mo supplementation trial of different folic acid doses: 100, 400, and 4000 µg/d and 4000 µg/wk. Plasma and RBC folate and plasma homocysteine concentrations were measured at baseline; after 1, 3, and 6 mo of supplementation; and 3 mo after discontinuation of supplementation. MTHFR genotyping was performed to identify a C→T mutation at position 677 (n = 932). RESULTS: Plasma and RBC folate and homocysteine concentrations were associated with MTHFR genotype throughout the supplementation trial, regardless of folic acid dose. MTHFR TT was associated with lower folate concentrations, and the trend of TT < CC was maintained at even the highest doses. Folic acid doses of 100 µg/d or 4000 µg/wk did not reduce high homocysteine concentrations in those with the MTHFR TT genotype. CONCLUSION: MTHFR genotype was an independent predictor of plasma and RBC folate and plasma homocysteine concentrations and did not have a significant interaction with folic acid dose during supplementation. This trial was registered at clinicaltrials.gov as NCT00207558.

Dietary iodine intake in the Chinese population.

OBJECTIVE: To evaluate dietary iodine intake and its potential risks among the Chinese population. METHODS: Individual dietary iodine intake was calculated using food consumption data multiplying by iodine concentration in foods, table salt and drinking water, followed by summing, and then compared with the corresponding age-specific reference values, including Upper Intake Level (UL) and Recommended Nutrient Intake (RNI). RESULTS: In areas with water iodine concentration (WI) lower than 150 µg/L, 80.8% of residents had iodine intake between the RNI and UL, 5.8% higher than UL, and the remaining (13.4%) lower than RNI if iodized salt was consumed. However, in the uniodized salt consumption scenario, only 1.0% of residents between RNI and UL, 1.4% higher than UL, and a large part of residents (97.6%) lower than RNI. In areas with WI higher than 150 µg/L, all residents had iodine intake between RNI and UL if iodized salt was consumed, except 10.5% and 24.9% of residents higher than UL in areas with WI at 150-300 µg/L and higher than 300 µg/L respectively. However, in the uniodized salt consumption scenario, only 1.5% and 1.7% of residents had higher iodine intake than UL respectively. CONCLUSION: The findings suggested that in general, the dietary iodine intake by the Chinese population was appropriate and safe at the present stage. People in areas with WI lower than 150 µg/L were more likely to have iodine deficiency. While people in areas with WI higher than 150 µg/L were more likely to have excessive iodine intake if iodized salt was consumed.

Iron, folate, and B(12) deficiencies and their associations with anemia among women of childbearing age in a rural area in Northern China.

OBJECTIVE: To assess the prevalence of folate, vitamin B(12), and iron deficiencies and their associations with anemia among women of childbearing age in northern China, an area with a reported high incidence of neural tube defects. METHODS: Plasma folate, vitamin B(12), ferritin, and hemoglobin levels were measured among 1,671 non-pregnant women of childbearing age from Xianghe County, Hebei Province, China in June 2004. RESULTS: Geometric means [95 % confidence interval (CI)] of plasma concentrations were 9.3 (4.0, 21.6) nmol/L for folate, 213.1 (82.4, 550.9) pmol/L for vitamin B(12), 17.4 (1.1, 278.6) microg/L for ferritin, and 129.9 (104.6, 161.4) g/L for hemoglobin (Hb). Approximately 24 % of women had biochemical evidence of folate deficiency (<6.8 nmol/L), 21.4 % were deficient (<148 pmol/L) in vitamin B(12), 30.2 % had iron depletion (<15 microg/L), and anemia (Hb < 120 g/L) was detected among 15.4 % of women. Of the three nutrients, only iron depletion (ferritin < 15 microg/L) was independently associated with anemia (adjusted odds ratio = 6.4, 95 % CI 4.8, 8.6). CONCLUSIONS: Although there were substantial proportions of folate and vitamin B(12) deficiencies among women of childbearing age in northern China, iron deficiency was the most important contributor to anemia.

Folate status and homocysteine response to folic acid doses and withdrawal among young Chinese women in a large-scale randomized double-blind trial.

BACKGROUND: There are no large randomized trials of the effect of folic acid dosing regimens on blood folate and homocysteine concentrations. OBJECTIVE: We aimed to evaluate the changes in folate and homocysteine concentrations in response to different folic acid doses and to withdrawal in young women not exposed to other sources of folic acid. DESIGN: Women (n = 1108) were randomly assigned to 1 of 6 intervention groups for which daily intakes of folic acid for 6 mo were 100 microg 1 time/d, 25 microg 4 times/d, 400 microg 1 time/d, 100 microg 4 times/d, 4000 microg 1 time/d, or 4000 microg 1 time/wk. Plasma and red blood cell folate and homocysteine concentrations were measured at baseline; at 1, 3, and 6 mo; and 3 mo after the discontinuation of folic acid. RESULTS: Folate and homocysteine concentrations were not different at baseline between the groups who had the same daily intake of folic acid as a single dose or multiple doses (P = 0.058). Plasma folate concentrations plateaued at 3 mo with 108% (95% CI: 97.7%, 120%), 259% (95% CI: 240%, 279%), 460% (95% CI: 417%, 503%), and 142% (95% CI: 123%, 162%) observed increases for the folic acid groups receiving 100, 400, and 4000 microg/d and 4000 microg/wk, respectively. The rate of reduction in folate concentrations during the 3 mo after cessation of folic acid was dose-dependent-higher intakes were associated with faster reductions. CONCLUSIONS: Changes in folate and homocysteine concentrations were unaffected by different dosing schedules. After folic acid cessation, blood folate declined rapidly, which indicated that the intervention-enhanced folate status was rapidly diminished.

[Evaluation on birth defects surveillance system in four counties of Shanxi province, China].

OBJECTIVE: To evaluate the reliability of the birth defects surveillance system in four counties with high prevalence of birth defects (Pingding, Xiyang, Taigu and Zezhou counties) in Shanxi province, China. METHODS: One township was selected from each county as study site. The health workers chosen from township or village level were trained to visit families on the outcomes of each pregnancy who gave birth during year 2003 in the study site. The number of births and cases collected in the study were compared with that from the surveillance system. The number of births reported by surveillance system in four counties was also compared with the data from the local government. The criteria of evaluation were: 1) number of the missing report of births should < or = 5%, 2) the number of missing report on major external birth defects cases should < or = 10%. Researchers from the Peking University were responsible for examining the quality of surveillance in some terminal units of surveillance system. RESULTS: The numbers of births reported in the study and from the surveillance system for four-township were 1043 and 997, respectively. 46 births were missing and the rate of misreporting for births was 4.4%. The numbers of birth defects cases reported in the study and from the surveillance system were 30 and 29, respectively. 1 case of birth defect as missed, and rate of misreporting for birth defects cases was 3.3%. The total number of births reported from surveillance was similar to that in the study in four counties, with a difference of 1.2%. Birth registry data was rather readable and special health workers responsible for surveillance work were present in all the terminal units of the surveillance system. CONCLUSION: The misreporting of births and cases existed in the birth defects surveillance system of the four counties in Shanxi province, but were lower than the allowable criteria. The surveillance units had better registration, reporting and administration of births and birth defect cases. Hence, the quality of the data from the surveillance system in these four counties was reliable.

[Study on the association between transforming growth factor alpha gene TaqI variant and cleft lip with or without cleft palate].

OBJECTIVE: To study the association between transforming growth factor alpha gene (TGFalpha) TaqI variant and nonsyndromic cleft lip with or without cleft palate (nsCL/P) in Chinese population. METHODS: TGFalpha TaqI variant was detected using polymerase chain reaction-restriction fragment length polymorphism for DNA samples of the 149 triads with nsCL/P affected child. We performed the Transmission/disequilibrium test and the family-based association study (FBAT) to identify the associations between this variant and risk of nsCL/P. RESULTS: Significant distortion of C2 allele at TGFalpha TaqI locus in nsCL/P groups (P > 0.05) was not found. In the family-based association test, C2 allele and offspring C2C1 genotype was not found to be significantly associated with an increase risk of nsCL/P (P > 0.05). CONCLUSION: Our findings did not suggest an association between offspring TGFalpha TaqI variant and the increased risk of nsCL/P in Chinese population.

[Association between parental transforming growth factor alpha gene TaqI variant, paternal smoking and the cleft lip with or without cleft palate].

OBJECTIVE: To study the association between transforming growth factor alpha gene (TGFalpha) TaqI variant and nonsyndromic cleft lip with or without cleft palate (nsCL/P) in Chinese population, and the interaction with parental smoking. METHODS: TGFalpha TaqI variant was detected using RFLP-PCR for DNA samples of the 170 triads with nsCL/P affected child. We performed the transmission/disequilibrium test (TDT) and the family-based association study (FBAT) to test the associations between this variant and risk of nsCL/P. RESULTS: It was not found significant distortion of C2 allele at TGFalpha TaqI locus in nsCL/P groups (P > 0.05), however, by stratified analysis, we found that the rate of C2 allele transmission among nuclear families whose fathers were smoking was 1/5 (0.062 - 0.711) as compared with that among nuclear families whose fathers were not smoking, and the OR of interaction between TGFalpha variant and parental smoking is 0.102 (0.017 - 0.619). CONCLUSION: The parental smoking may interact with TGFalpha variants of Chinese populations in occurrence of nsCL/P, but it remains to have more investigations.

[Epidemiological study on reduced folate carrier gene(RFC1 A80G) polymorphism and other risk factors of neural tube defects].

OBJECTIVE: To study the reduced folate carrier gene (RFC1) A80G polymorphism and other factors influence on children with neural tube defects (NTDs) and provide the epidemiological evidence for finding genetic marker of NTDs. METHODS: RFC1(A80G) genotypes were detected using polymerase chain reaction-restriction fragment length polymorphism (RFLP-PCR) for blood DNA of 104 trios with NTDs-affected by child, and the 100 control families without child-affected by any birth defects. We performed the analysis of multifactors logistic regression for RFC1 genotypes and other factors in order to investigate the RFC1 genotype of the nuclear families and maternal periconceptional folic acid supplementation influence on NTDs independently. Transmission/disequilibrium test (TDT) for the RFC1 genotype of NTDs and control pedigree were carried out. RESULTS: The RFC1 G allele frequency of children with NTDs (64.42%) was higher than that of the control children (52.53%), and there was the significant difference between them (chi(2)=5.9198, P<0.05). We observed that the infants of the GG genotype were associated with a 2.56-fold increased risk of NTDs when compared with the AA genotype (95% CI=1.04-6.36), The risk of mothers who did not take folic acid for having an NTDs-affected infants was 7.69 (95% CI=2.86-21.75). There were significant differences between cases and controls in the other risk factors, such as paternal age (> or =30), maternal fever during the early pregnancy, the history of maternal spontaneous abortion. In the logistic regression analysis, of multifactors the three factors, for example, the offspring of the RFC1 GG genotype (OR=2.91, 95% CI=1.35-6.30), maternal periconceptional folic acid supplementation (OR=4.32, 95% CI=1.62-11.55), maternal fever during the early pregnancy, had the statistic significance for the risk of NTDs. There was the evidence of an association between G allele and the risk of the maternal having a child with NTDs (OR=1.56, 95% CI=1.07-2.28) in TDT analysis. CONCLUSION: Our findings indicate that the RFC1 genotype (GG) is a possible susceptible gene marker for an increased NTDs risk in this Chinese population, and there is a potential influence on the risk of NTDs in maternal periconceptional folic acid supplementation, and maternal fever during the early pregnancy.

Interaction between maternal periconceptional supplementation of folic acid and reduced folate carrier gene polymorphism of neural tube defects.

OBJECTIVE: To search the interaction between reduced folate carrier gene (RFC1 A80G) polymorphism of children with neural tube defects (NTDs) and maternal periconceptional no supplementation of folic acid. The purpose is to provide the epidemiological evidence for finding genetic marker of NTDs. METHODS: RFC1 (A80G) genotype was detected using PCR-restricted fragment length polymorphism for the blood DNA of 104 trios with NTDs-affected child, and 100 control families with non-malformed control children. The authors investigated the gene-environment interactions between the offspring RFC1 genotype and maternal periconceptional folic acid supplementation through a case-control study. RESULTS: It was observed that the offspring with the GG genotype were associated with a 2.56-fold increased risk of NTDs when compared to those with the AA genotype (OR = 2.56; 95% CI = 1.04-6.36) in this population under investigation. The risk of mothers who did not take folic acid for having an NTDs-affected infants was 7.69 (95% CI = 2.86-21.75). Among the mothers who did not utilize folic acid supplements, the NTDs risk was 3.30 (95% CI = 1.15-9.65) for offspring with the GG genotype, compared to the reference (AA) genotype. Children who had the GG genotype and whose mothers did not take folic acid had an elevated risk for NTDs (OR = 8.80, 95% CI = 2.86 - 29.82), compared to "offspring with AA or GA genotype" and "maternal folic acid use", the interactive coefficient being 1.45. CONCLUSION: The above findings indicate that the RFC1 genotype (GG) is a possible susceptible gene marker for an increased NTDs risk in Chinese population, and there is a potential gene-nutrient interaction between offspring RFC1 GG genotype and maternal periconceptional intake of folic acid on the risk of NTDs. However,the sample size of this study was limited, a larger sample of population-based study is required to pursue the initial observation.

[A parental case control study on the association between reduced folate carrier gene polymorphism and neural tube defects].

OBJECTIVE: To study the association between reduced folate carrier gene (RFC1 A80G) polymorphism and the risk for child with neural tube defects (NTDs), and to provide epidemiological evidence for the existence of NTDs genetic marker. METHODS: RFC1 (A80G) genotypes were detected using RFLP-PCR for blood DNA of 104 families with NTDs-affected children and 100 control families with no history of child-affected birth defects. Case-control study and transmission/disequilibrium test(TDT) for the RFC1 genotype of NTDs pedigree were carried out. RESULTS: The G allele frequency of children with NTDs was higher than that of controls when compared to A allele( OR = 1. 64, 95% CI :1.08-2.49). The offspring of the GG genotype were associated with a 2.56-fold increased risk of NTDs when compared to the AA genotype (OR = 2.56, 95% CI: 1.04-6.36) in our study population. There was evidence of association between G allele and the risk of parent having a child with NTDs (OR = 1.56, 95% CI: 1.07-2.28) in the TDT analysis. CONCLUSION: Our findings indicated that there was potential association between offspring RFC1 GG genotype and the risk of NTDs, and the G allele was a possible susceptible gene marker for an increased NTDs risk in the Chinese population.

[Study on the association between reduced folate carrier gene polymorphism and congenital heart defects and cleft lip with or without cleft palate].

OBJECTIVE: To study the association between reduced folate carrier gene (RFC1) polymorphism and congenital heart defects (CHD) as well as cleft lip with or without cleft palate (CLP) and to provide epidemiological evidence on genetic markers of CHD and CLP. METHODS: RFC1 (A80G) genotype was detected using RFLP-PCR for blood DNA of the 67 triads with nonsyndromic CHD-affected child, the 82 triads with child-affected cleft lip with or without CLP and the 100 control families without child-affected birth defects. We performed a family-based association test and analyzed the interaction between RFC1 A80G genotype and maternal periconceptional supplementation of folic acid. RESULTS: Offspring of mothers who did not take folic acid had an elevated risk for CHD when comparing with offspring of mothers who did (OR = 2.68, 95% CI: 1.14 - 6.41). There was a statistical association between the risk of CHD and maternal periconceptional folic acid supplementation (chi(2) = 6.213, P < 0.05). In the family-based association test, G allele was positively associated with an increased risk for children CHD (Z = 2.140, P < 0.05) while G allele of RFC1 (A80G) polymorphism might increase the risk for CHD. Elevated risks for either CLP group were not observed between RFC1 genotype using or not using folic acid. CONCLUSION: Our findings suggested that the G allele was likely to be a genetically susceptible allele for CHD. There was possible association between offspring with GG, GA genotype and maternal periconceptional folicacid deficiency.