Animals ; Cattle ; China ; Dairy Products ; Food Contamination ; Humans ; Infant ; Infant Formula ; chemistry ; Milk ; Triazines ; chemistry

OBJECTIVESTo study the migration of melamine into foods from plastic food packaging materials and dairy product containers commonly used in China.

METHODS37 samples were collected from the market. The EU migration testing conditions were adopted with distilled water, 3% acetic acid, n-hexane and 15% ethanol being chosen as the simulating solutions. The HPLC method was used to detect melamine.

RESULTSNo melamine was detected in 15 dairy product containers. Among the 22 plastic samples, 16 of polypropylene, and polycarbonate types had no detectable amount melamine while a low level of melamine was found in 3 of the 6 melamine resin containers.

CONCLUSIONMigration of melamine from food packaging materials in China market is in line with the requirements of EU.

Animals ; Cattle ; China ; Dairy Products ; Diffusion ; Food Analysis ; Food Contamination ; Food Packaging ; Milk ; Plastics ; chemistry ; Spectrophotometry, Ultraviolet ; Triazines ; chemistry

OBJECTIVETo estimate the dietary melamine exposure in Chinese infants and young children from the consumption of melamine adulterated Sanlu infant formula.

METHODSFour age groups of infants and young children (3, 6, 12, and 24 months) were chosen as the assessed subjects and the maximum amount of infant formula consumption was estimated based on the recommended usage level in the package insert of Sanlu infant formula and other brands. Melamine was analyzed in 111 Sanlu infant formula samples collected from the markets in Beijing and Gansu province using the LC-MS-MS with a limit of quantification of 0.05 mg/kg. Four levels of melamine concentration were chosen to estimate the dietary intakes, including the mean, median, 90th percentile, and maximum.

RESULTSThe infants of 3 months had the highest intake of melamine, and with the increase of the age (month), the intake decreased. Based on the median melamine concentration (1,000 mg/kg) as an example, the melamine intakes for the infants of 3, 6, 12, and 24 months were 23.4, 21.4, 15.0, and 8.6 mg/kg bw/d, respectively.

CONCLUSIONDietary melamine intakes from tainted Sanlu infant formula significantly exceeded the TDI level (0.2 mg/kg bw/d) recommended by the WHO Expert Meeting in 2008. However, the present assessment has some limitations including the poor representative samples, the varied melamine concentrations in the adulterated Sanlu infant formula, and other brand infant formula possibly consumed by these infants.

China ; Diet ; Eating ; Female ; Flame Retardants ; analysis ; metabolism ; Food Contamination ; Humans ; Infant ; Infant Formula ; chemistry ; Male ; Triazines ; chemistry ; metabolism

OBJECTIVETo investigate the occurrence and concentrations of melamine and its analogues in tainted infant formula and to identify the etiologic factors for the urinary stones epidemic in infants and young children in China in 2008.

METHODSSanlu infant formula samples were collected from families of the affected children in Gansu province, and markets in Gansu and Hebei provinces and Beijing city. Melamine and its analogues, including cyanuric acid, ammeline, and ammelide were measured by gas chromatography/tandem mass spectrometry.

RESULTSHigh prevalence and concentrations of melamine were found in Sanlu infant formula samples, with low concentrations of cyanuric acid, ammeline and ammelide. Melamine were detected in 87 out of 111 Sanlu infant formula samples with a range of 118 to 4,700 mg/kg.

CONCLUSIONThe results provide strong evidence for melamine as the etiological factor for the urinary stones epidemic in infants and young children in China in 2008.

China ; Flame Retardants ; analysis ; Food Contamination ; Humans ; Infant ; Infant Formula ; chemistry ; Triazines ; chemistry

OBJECTIVETo develop an analytical method for simultaneously qualitative and quantitative determination of melamine and triazine-related by-products including ammelide, ammeline, and cyanuric acid in milk and milk products by gas chromatography-tandem mass spectrometry (GC-MS/MS).

METHODSMelamine and triazine-related by-products namely ammelide, ammeline and cyanuric acid in the samples were extracted in a solvent mixture of diethylamine, water, and acetonitrile (10:40:50, V/V/V). After centrifugation, an aliquot of the supernatant was evaporated to dryness under a gentle stream of nitrogen gas, and then melamine and triazine-related by-products were derivatized using BSTFA with 1% TMCS. The derivatives of melamine and its analogues were determined by gas chromatography/tandem mass spectrometry using multiple reactional monitoring (MRM) with 2, 6-Diamino-4-chloropyrimidine (DACP) being used as an internal standard.

RESULTSThe linear detectable ranges were from 0.004 mg/kg to 1.6 mg/kg for melamine, ammelide, ammeline, and cyanuric acid with a correlation coefficient no less than 0.999. The recovery rates of the four compounds in spiked blank milk powder at concentrations 0.5, 1, 2 mg/kg were between 61.4%-117.2%, and the relative standard deviation was no more than 11.5% (n=6). The detection limits of melamine, ammelide, ammeline and cyanuric acid in milk powder were 0.002 mg/kg with a ratio of signal to noise of 3.

CONCLUSIONThis GC-MS/MS method for simultaneous determination of melamine, ammelide, ammeline, and cyanuric acid in milk and milk products is sensitive and specific.

Animals ; Cattle ; Chromatography, Gas ; Flame Retardants ; analysis ; Food Contamination ; Milk ; chemistry ; Molecular Sequence Data ; Sensitivity and Specificity ; Tandem Mass Spectrometry ; Triazines ; chemistry

OBJECTIVETo investigate the potential mechanisms of cell death after the treatment with ceramide.

METHODSMTT assay, DNA ladder, reporter assay, FACS and Western blot assay were employed to investigate the potential mechanisms of cell death after the treatment with C2-ceramide.

RESULTSA short-time treatment with C2-ceramide induced cell death, which was associated with p38 MAP kinase activation, but had no links with typical caspase activation or PARP degradation. Rather than caspase inhibitor, Inhibitor of p38 MAP kinase blocked cell death induced by a short-time treatment with ceramide (<12 h). However, inhibition of p38 MAP kinase could not block cell death induced by a prolonged treatment with ceramide (>12 h). Moreover, incubation of cells with ceramide for a long time (>12 h) increased subG1, but reduced S phase accompanied by caspase-dependent and caspase-independent changes including NFkappaB activation.

CONCLUSIONCeramide-induced cell apoptosis involves both caspase-dependent and -independent signaling pathway. Caspase-independent cell death occurring in a relatively early stage, which is mediated via p38 MAP kinase, can progress into a stage involving both caspase-dependent and -independent mechanisms accompanied by cell signaling of MAPKs and NFkappaB.

Apoptosis ; drug effects ; physiology ; Caspases ; metabolism ; physiology ; Flow Cytometry ; HT29 Cells ; Humans ; NF-kappa B ; metabolism ; physiology ; Signal Transduction ; Sphingosine ; analogs & derivatives ; pharmacology ; p38 Mitogen-Activated Protein Kinases ; physiology

OBJECTIVETo explore the changes in spatial learning performance and long-term potentiation (LTP) which is recognized as a component of the cellular basis of learning and memory in normal and lead-exposed rats after administration of melatonin (MT) for two months.

METHODSExperiment was performed in adult male Wistar rats (12 controls, 12 exposed to melatonin treatment, 10 exposed to lead and 10 exposed to lead and melatonin treatment). The lead-exposed rats received 0.2% lead acetate solution from their birth day while the control rats drank tap water. Melatonin (3 mg/kg) or vehicle was administered to the control and lead-exposed rats from the time of their weaning by gastric gavage each day for 60 days, depending on their groups. At the age of 81-90 days, all the animals were subjected to Morris water maze test and then used for extracellular recording of LTP in the dentate gyrus (DG) area of the hippocampus in vivo.

RESULTSLow dose of melatonin given from weaning for two months impaired LTP in the DG area of hippocampus and induced learning and memory deficit in the control rats. When melatonin was administered over a prolonged period to the lead-exposed rats, it exacerbated LTP impairment, learning and memory deficit induced by lead.

CONCLUSIONMelatonin is not suitable for normal and lead-exposed children.

Animals ; Female ; Lead ; toxicity ; Learning ; drug effects ; Long-Term Potentiation ; drug effects ; Male ; Maze Learning ; drug effects ; Melatonin ; administration & dosage ; toxicity ; Rats ; Spatial Behavior ; drug effects

OBJECTIVETo establish a reliable platform for screening glucokinase activators (GKAs) in vitro.

METHODSPancreatic glucokinase (PGK) protein expressed in a prokaryotic expression system as a histidine-tagged fusion protein from Homo sapiens was produced. Then, response surface methodology (RSM) was used to optimize the microplate-based GKA screening platform. In the first step of optimization with Plackett-Burman design (PBD), initial pH, reaction time and MgCl2 were found to be important factors affecting the activity ratio of GKA (RO-28-1675) significantly. In the second step, a 2(3) full factorial central composite design (CCD) and RSM were applied to the optimal condition determination of each significant variable. A second-order polynomial was determined by a multiple regression analysis of the experimental data.

RESULTSThe following optimal values for the critical factors were obtained: initial pH 0 (7.0), reaction time-0.63 (13.7 min) and MgCl2 0.11 (2.11 mmol/L) with a predicted value of the maximum activity ratio of 34.1%.

CONCLUSIONUnder the optimal conditions, the practical activity ratio is 34.8%. The determination coefficient (R2) is 0.9442, ensuring adequate credibility of the model. LLAE3, extracted from Folium nelumbinis in our laboratory, has prominently activated effects on PGK.

Analysis of Variance ; Drug Discovery ; methods ; Enzyme Activators ; analysis ; Escherichia coli ; genetics ; Genetic Vectors ; Glucokinase ; metabolism ; Humans ; Hydrogen-Ion Concentration ; Hypoglycemic Agents ; analysis ; Kinetics ; Time Factors

OBJECTIVETo study the circulation, distribution, and genomic diversity of HPVs in common warts in Beijing area of China.

METHODSForty eight patients with pathologically diagnosed common warts were screened for the presence of HPV with HPV type-specific PCR and direct sequencing analysis. The genomic diversity of HPVs prevalent in Chinese patients was analyzed based on LCR.

RESULTSForty one (85.5%) samples were positive for HPV DNA, 13 (31.7%)--HPV-57, 12 (29.3%)--HPV-1a, 7 (17%)--HPV-27 and 5(12.2%)--HPV-2a. Four cases were infected with two different HPV types, two (4.9%) with HPV-1a and HPV-27, one (2.4%) with HPV-1 and HPV-57 and one (2.4%) with HPV-27 and HPV-57. In contrast to the prevalence of single strain of novel HPV-57 variant and HPV-1 prototype, two HPV-2 and three HPV-27 novel variants were found to circulate in Beijing.

CONCLUSIONHPV-1, -2, -27 and -57 are predominantly prevalent in patients with common warts in Beijing.

Adolescent ; Adult ; Aged ; China ; epidemiology ; DNA, Viral ; Female ; Genetic Variation ; Humans ; Male ; Middle Aged ; Papillomaviridae ; classification ; genetics ; isolation & purification ; Phylogeny ; Prevalence ; Warts ; epidemiology ; virology

OBJECTIVETo further investigate the neuroprotective effects of five isoflavonoids from Astragalus mongholicus on xanthine (XA)/ xanthine oxidase (XO)-induced injury to PC12 cells.

METHODSPC12 cells were damaged by XA/XO. The activities of antioxidant enzymes, MTT, LDH, and GSH assays were used to evaluate the protection of these five isoflavonoids. Contents of Bcl-2 family proteins were determined with flow cytometry.

RESULTSAmong the five isoflavonoids including formononetin, ononin, 9, 10-dimethoxypterocarpan-3-O-beta-D-glucoside, calycosin and calycosin-7-O-glucoside, calycosin and calycosin-7-O-glucoside were found to inhibit XA/ XO-induced injury to PC12 cells. Their EC50 values of formononetin and calycosin were 0.05 microg/mL. Moreover, treatment with these three isoflavonoids prevented a decrease in the activities of antioxidant enzymes, superoxide dismutase (SOD) and glutathione peroxidase (GSH-Px), while formononetin and calycosin could prevent a significant deletion of GSH. In addition, only calycosin and calycosin-7-O-glucoside were shown to inhibit XO activity in cell-free system, with an approximate IC50 value of 10 microg/mL and 50 microg/mL. Formononetin and calycosin had no significant influence on Bcl-2 or Bax protein contents.

CONCLUSIONNeuroprotection of formononetin, calycosin and calycosin-7-O-glucoside may be mediated by increasing endogenous antioxidants, rather by inhibiting XO activities or by scavenging free radicals.

Animals ; Astragalus Plant ; chemistry ; Glucosides ; chemistry ; isolation & purification ; pharmacology ; Glutathione ; metabolism ; Glutathione Peroxidase ; metabolism ; Isoflavones ; chemistry ; isolation & purification ; pharmacology ; PC12 Cells ; Protective Agents ; isolation & purification ; pharmacology ; Proto-Oncogene Proteins c-bcl-2 ; metabolism ; Rats ; Superoxide Dismutase ; metabolism ; Xanthine Oxidase ; antagonists & inhibitors ; pharmacology