Intellectual impairment in children exposed to polychlorinated biphenyls in utero

BACKGROUND: In utero exposure to polychlorinated biphenyls, a ubiquitous environmental contaminant, has been linked to adverse effects on neurologic and intellectual function in infants and young children. We assessed whether these effects persist through school age and examined their importance in the acquisition of reading and arithmetic skills. METHODS: We tested 212 children, recruited as newborns to overrepresent infants born to women who had eaten Lake Michigan fish contaminated with polychlorinated biphenyls. A battery of IQ and achievement tests was administered when the children were 11 years of age. Concentrations of polychlorinated biphenyls in maternal serum and milk at delivery were slightly higher than in the general population. A composite measure of prenatal exposure was derived from concentrations in umbilical-cord serum and maternal serum and milk. RESULTS: Prenatal exposure to polychlorinated biphenyls was associated with lower full-scale and verbal IQ scores after control for potential confounding variables such as socioeconomic status (P = 0.02). The strongest effects related to memory and attention. The most highly exposed children were three times as likely to have low average IQ scores (P <0.001) and twice as likely to be at least two years behind in reading comprehension (P = 0.03). Although larger quantities of polychlorinated biphenyls are transferred by breast-feeding than in utero, there were deficits only in associated with transplacental exposure, suggesting that the developing fetal brain is particularly sensitive to these compounds. CONCLUSIONS: In utero exposure to polychlorinated biphenyls in concentrations slightly higher than those in the general population can have a long-term impact on intellectual function.     

Degradation of nonionic surfactants and polychlorinated biphenyls by recombinant field application vectors

Immunoglobin binding protein (BiP) molecules exist as both monomers and oligomers and phosphorylated BiP is restricted to the oligomeric pool. Modified BiP is not bound to proteins such as immunoglobulin heavy chain and consequently, may constitute an inactive form. Unlike earlier analysis of mammalian BiP isolated by two-dimensional gel electrophoresis, results here demonstrated that immunoprecipitated BiP displayed predominantly threonine phosphorylation with only a trace of detectable phosphoserine. Like other Hsp70 family members, BiP is comprised of three domains: an amino terminal domain which binds nucleotide, an 18 kilodalton domain which binds peptide, and a carboxyl terminal variable domain of unknown function. Cyanogen bromide cleavage and enzymatic digestion experiments mapped threonine phosphorylation to a site within a 47 amino acid sequence of the peptide binding domain which contains seven threonine residues. Partial proteinase K digestion in the presence of ATP independently verified that the in vivo phosphorylation site of mammalian (BiP) is located within the peptide binding domain. Furthermore, phosphorylation did not impede BiPs ATP-induced conformational change. Thus, the peptide binding domain of BiP is phosphorylated on threonine residue(s) mapping to not more than two tryptic fragments within the peptide binding domain. This location on the molecule could explain why phosphorylated BiP is not detected bound to proteins in vivo.     

Isoxaben soil biodegradation in pear tree orchard after repeated high dose application

Dose uniformity within the treatment volume for tangent breast irradiation can be significantly improved through dynamic compensating collimation using all four independent jaws to define a superposition of sequentially reduced Enhanced dynamic wedge fields. The enhanced dynamic wedge angle is determined which optimizes dose uniformity in the central axis transverse plane, then the sequential reduction of the superior and inferior jaws is determined to optimize the sagittal dose uniformity. This technique could be applied under computer control through a record and verify system.     

贵阳市花溪河水体及沉积物中多氯联苯的污染状况研究

[目的]调查贵阳市花溪河水体及沉积物中的多氯联苯(PCBs)的污染状况.[方法]样品分别于丰水期及桔水期在6个采样点采集,经过处理后,利用GC-ECD检测PCBs的含量.[结果]花溪河水体及沉积物中PCBs含量分别为0.01～0.09、0.82～2.76 ng/g.[结论]花溪河水体及沉积物中均受到一定程度的PCBs污染,与国内外污染区相比,PCBs的含量较低.     

Gas chromatography determination of polychlorinated biphenyls in powdered and liquid soybean milks

OBJECTIVE: To compare the inhibitory effects of propiverine HCl(BUP-4) with those of atropine and oxybutynin on the detrusor instability induced by partial obstruction of the bladder neck of female rats. MATERIALS AND METHODS: Partial obstruction was created using partial ligation of the proximal urethra in 20 female Sprague-Dawley rats. Both the obstructed rats and a control group of 15 rats were evaluated cystometrically about 6 weeks later and the values compared both baseline and after injection with BUP-4, atropine or oxybutynin. During cystometry, the bladder capacity (BC), residual volume (RV), compliance and frequency of spontaneous activity (SA) were determined. RESULTS: The BC, RV and frequency of SA were significantly increased, and compliance markedly decreased, in obstructed compared with normal rats. The micturition pressure was significantly decreased only after injection with BUP-4 in both normal and obstructed rats. For both, the BC was increased significantly after injection with atropine or BUP-4 (P < 0.05), with the increase greater after BUP-4 than after atropine in both groups (P < 0.01). After injecting BUP-4, the RV was significantly increased in both groups (P < 0.05); atropine increased the RV only in normal rats (P < 0.01) and oxybutynin had no significant effect on RV. Increases in compliance after the administration of each drug were significant only in obstructed rats (P < 0.01) and were markedly higher after oxybutynin (780%) than after the other drugs (180-250%). The frequencies and amplitude of SA after injection with each drug were significantly lower only in obstructed rats, but in these rats, there were no significant differences in this reduction after injecting oxybutynin or BUP-4, whereas they were significantly greater after injecting oxybutynin than after atropine. CONCLUSION: Partial bladder outlet obstruction successfully created a hyperactive (unstable) bladder, typified by increased BC, RV, frequency of SA and a marked decrease in compliance. The greater BC, lower MP and frequency and amplitude of SA were prominent after the administration of BUP-4. Thus it is suggested that BUP-4 effectively inhibited bladder instability in rats induced by infravesical outlet obstruction and was more effective than oxybutynin in increasing BC.     

Inhibition of thyroid hormone sulfation by hydroxylated metabolites of polychlorinated biphenyls

A novel method for the preparation of N-acylchitosan fiber and N-acylchitosan-cellulose fiber is described. Each aqueous solution of sodium N-acetyl and N-propionylchitosan salts in aqueous 14% NaOH was spun through a viscose-type spinneret at 10-15 degrees C into a coagulating bath containing aqueous 10%, H2SO4. 25% Na2SO4 and 1.3% ZnSO4 to afford the corresponding white fiber. By the same method, a clear solution of sodium N-acetyl and N-propionyl chitosan salts were respectively mixed with sodium cellulose xanthate in aqueous 14% NaOH and spun to afford the corresponding white N-acylchitosan-cellulose fiber. Their filament tenacity and elongation values were 0.4-0.7 times as large as cellulose. These fibers were digestible in reactions by chitinase and lysozyme, and the digestibility was controlled by the structure of the N-acyl group.     

Enhanced degradation of polychlorinated biphenyls by directed evolution of biphenyl dioxygenase

Data characterizing is considered the first and main stage of the statistical analysis. Rather than characterizing each biomechanical signal through one or few global indicators, such as the mean or the root mean square, this paper suggests first to cut the scale into several fuzzy windows and to summarize the data within each window through an occurrence indicator. These indicators become the analysis variables. They can be analyzed through the multiple correspondence analysis, which shows the most discriminant variables, connections between them, empirical situation classes and correspondences between these classes and the most discriminant variables. An example is considered for arguing our point of view; it concerns characterizing and analysis of forces situated at the hand, foot and back level in a load lifting task.     

Effects of environmental exposure to polychlorinated biphenyls and dioxins on birth size and growth in Dutch children

BACKGROUND: The nature of the breakdown products produced in enterocytes during epithelial transport of intact proteins may be critical in determining the functional consequences of protein absorption. AIM: (a) To measure the transepithelial transport of horseradish peroxidase (HRP) and to identify the nature of HRP breakdown products released on the basal side of enterocytes and (b) to assess the role of interferon gamma (IFN gamma) on HRP transport and processing. METHODS: HT29-19A intestinal cells were used to assess transepithelial transport of HRP in Ussing chambers, and the nature of breakdown products in the basal compartment was analysed by high performance liquid chromatography (HPLC). RESULTS: (1) In control conditions, [3H]HRP equivalent fluxes (3135 (219) ng/h per cm2; mean (SEM) comprised 50% amino acids, 40% peptides, and 10% intact HRP. Steric exclusion HPLC of the breakdown products indicated a wide range of molecular masses including a major peptide of about 1150 Da. Lysosomal aspartyl and thiol proteases were expressed but no HLA-DR surface expression was noted, (2) At 48 to 72 hours after IFN gamma stimulation, [3H]HRP equivalent fluxes increased significantly (7392 (1433) ng/h per cm2) without modification of the relative proportions of amino acids, peptides, and intact HRP, and without modification of the distribution of breakdown products in HPLC. Lysosomal protease activities were not modified by IFN gamma but HLA-DR expression was increased. CONCLUSION: Intestinal cells are able to process HRP into peptides potentially capable of stimulating the immune system. IFN gamma stimulates the transport and processing of HRP thus increasing the antigenic load in the intestinal mucosa.     

Levels of polychlorinated biphenyls in some waste motor and transformer oils from Poland

Waste motor and transformer oils are considered as a main source of polychlorinated biphenyls (PCBs) emission into the environment. The levels of total PCB in twenty six randomly selected samples of waste motor and transformer oils from different regions of Poland were studied. The clean-up of the extracts on two solid phase extraction columns system and determination of PCBs by capillary gas chromatography with electron capture detection were performed. The determined content of PCBs in motor oils was by one order of magnitude higher than in transformer oils, but in the both types of analysed samples, except one sample, did not exceed 50 micrograms/g.     

Factors affecting the biodegradation of toluene in soil

The biodegradation of toluene in soil microcosms was examined in order to identify the physical, chemical, and biological factors which determine the fate and lifetime of organic chemicals in soils. Toluene degradation rates were proportional to the initial substrate concentration and these rates reached a maximum at a concentration of 200 micrograms/g. No degradation occurred above this concentration presumably due to the toxicity of the hydrocarbon to the soil microorganisms. Small differences were observed in the degradation rates in soils at different moisture content. However, the availability of water in soil appeared to limit toluene degradation only at a very low water content. The lifetime of toluene in soil was also related to the initial level and activity of the soil microorganisms. Toluene was metabolized rapidly in those soils which initially contained high levels of degrading microorganisms. Furthermore, exposure of the soil to toluene resulted in an increase in the number of degrading organisms. The lack of inorganic nutrients such as nitrogen prevented complete degradation of toluene in a clay soil which contained high levels of degrading microorganisms. The biodegradation of organic chemicals in soil is not an intrinsic property of the molecule and cannot be predicted without first delineating the environment in which it is found. The biodegradation of a compound is defined by the biological, physical, and chemical characteristics of the soil environment. The lifetime of a chemical in soil results from a combination of all three of these parameters.     

Liquid-gel partitioning using Lipidex in the determination of polychlorinated biphenyls in cod liver oil

A technique was developed for transfer of fat and polychlorinated biphenyls from cod liver oil into the lipophilic gel Lipidex 5000. Subsequent elution of the gel separated about 60% of the fat from the sample. Following further purification on aluminium oxide and silica gel, toxic non-ortho- and mono-ortho-PCB congeners were isolated in two separate fractions on charcoal. Recoveries were studied by addition of twelve different PCB congeners to 0.2 g of fat. The non-ortho-PCBs were labelled with 13C. The recoveries of 5-50 ng of the unlabelled compounds were 80-100% and those of 50-100 pg of the labelled compounds were 76-106%.     

The effect of chlorine substitution on the dermal absorption of polychlorinated biphenyls

This study investigated the characteristics of computer-based case simulations (CCS) that may be associated with case difficulty. Difficulty was defined as the average rating by physicians of examinee performance on a nine-point scale or the passing rate on the cases. Two data sets were used, one from an administration of 18 cases, the other from an administration of 22 cases with 13 cases used on both occasions. Stepwise regression procedures were used separately for case properties and for analytic scoring of key variables to identify the best sets of predictors of case difficulty. Because of the small number of cases, regression results were evaluated for consistency across both data and both difficulty measures. For key variables, the best set of predictors included the number of different serious errors of commission, risk items, and benefit items. In general, cases were more difficult for higher values of these variables. For case variables, the only consistent variable was the length of the paragraph that provided patient history, with longer paragraphs associated with more difficult cases. Other variables were less consistent, but were often related to the structure of the simulation or the severity of the patient condition. Although the findings for case variables were limited, the analyses were very helpful in illuminating the interconnections among the variables within cases.     

Hydrocarbons and polychlorinated biphenyls from the unsaponifiable fraction of anhydrous milk fat

Using a combination of gas-liquid chromatography and mass spectrometry, the presence of 39 aliphatic hydrocarbons was firmly established in the unsaponifiable fraction of anhydrous milk fat. The hydrocarbons were the C(14) to C(27) and the C(29) to C(31) straight-chain paraffins, their monoolefin analogs, and the C(25) to C(29) branched alkanes. Phytene (3,7,11,15-tetramethyl-n-hexadec-2-ene), identified for the first time in milk fat, was isolated and identified by high-resolution mass spectrometry and infrared analysis. The total hydrocarbon content amounted to 30 ppm of the milk fat. Polychlorinated biphenyls also were detected in trace amounts in the area of the chromatogram between the C(18) and the C(23) hydrocarbons.     

Quantitative analysis of polychlorinated biphenyls, organochlorine insecticides, polycyclic aromatic hydrocarbons, polychlorinated hydrocarbons and polynitrohydrocarbons in spiked samples of soil, water and plasma by selected-ion monitoring gas chromatography-mass spectrometry

The current study assesses the relationship between presenting symptomatology of the self-labeled Hispanic popular diagnosis of ataques de nervios and the specific co-morbid psychiatric diagnoses. Hispanic subjects seeking treatment at an anxiety disorders clinic (n = 156) were assessed with a specially designed self-report instrument for both traditional ataque de nervios and panic symptoms, and with structured or semistructured psychiatric interviews for Axis-I disorders. This report focuses on 102 subjects with ataque de nervios who also met criteria for panic disorder, other anxiety disorders, or an affective disorder. Distinct ataque symptom patterns correlated with co-existing panic disorder, affective disorders, or other anxiety disorders. Individuals with both ataque and panic disorder reported the most asphyxia, fear of dying, and increased fear during their ataques. People with ataques who also met criteria for affective disorder reported the most anger, screaming, becoming aggressive, and breaking things during ataques. Ataque positive subjects with other anxiety disorders were less salient for both panic-like and emotional-anger symptoms. The findings suggest that (a) ataque de nervios is a popular label referring to several distinct patterns of loss of emotional control, (b) the type of loss of emotional control is influenced by the associated psychiatric disorder, and (c) ataque symptom patterns may be a useful clinical marker for detecting psychiatric disorders. Further study is needed to examine the relationship between ataque de nervios and psychiatric disorders, as well as the relationship to cultural, demographic, environmental, and personality factors.     

Interactive effects of three structurally different polychlorinated biphenyls in a rat liver tumor promotion bioassay

PURPOSE: Our goal was to validate linear and nonlinear intersubject image registration using an automated method (AIR 3.0) based on voxel intensity. METHOD: PET and MRI data from 22 normal subjects were registered to corresponding averaged PET or MRI brain atlases using several specific linear and nonlinear spatial transformation models with an automated algorithm. Validation was based on anatomically defined landmarks. RESULTS: Automated registration produced results that were superior to a manual nine parameter variant of the Talairach registration method. Increasing the degrees of freedom in the spatial transformation model improved the accuracy of automated intersubject registration. CONCLUSION: Linear or nonlinear automated intersubject registration based on voxel intensities is computationally practical and produces more accurate alignment of homologous landmarks than manual nine parameter Talairach registration. Nonlinear models provide better registration than linear models but are slower.     

Purification and preliminary characterization of a serine hydrolase involved in the microbial degradation of polychlorinated biphenyls

2-Hydroxy-6-oxo-6-phenylhexa-2,4-dienoate (6-phenyl-HODA) hydrolase (BphD), an enzyme of the biphenyl biodegradation pathway encoded by the bphD gene of Burkholderia cepacia LB400, was hyperexpressed and purified to apparent homogeneity. SDS-polyacrylamide gel electrophoresis confirmed that BphD has a subunit molecular mass of 32 kDa, while gel filtration demonstrated that it is a homotetramer of molecular weight 122,000. The enzyme hydrolyzed 6-phenyl-HODA with a kcat of 5.0 (+/- 0.07) s-1 and a kcat/Km of 2.0 (+/- 0.08) x 10(7) M-1 s-1 (100 mM phosphate, pH 7.5, 25 degreesC). The specificity of BphD for other 2-hydroxy-6-oxohexa-2,4-dienoates (HODAs) decreased markedly with the size of the C6 substituent; 6-methyl-HODA, the meta cleavage product of 3-methylcatechol, was hydrolyzed approximately 2300 times less specifically than 6-phenyl-HODA. By comparison, the homologous hydrolase from the toluene degradation pathway, TodF, showed highest specificity for 6-methyl- and 6-ethyl-HODA (kcat/Km of 2.0 (+/- 0.05) x 10(6) M-1 s-1 and 9.0 (+/- 0.5) x 10(6) M-1 s-1, respectively). TodF showed no detectable activity toward 6-phenyl-HODA and 6-tert-butyl-HODA. Neither BphD nor TodF hydrolyzed 5-methyl-HODA efficiently. The kcat of BphD determined by monitoring product formation was about half that determined by monitoring substrate disappearance, suggesting that some uncoupling of substrate utilization and product formation occurs during the enzyme catalyzed reaction. Crystals of BphD were obtained using ammonium sulfate combined with polyethylene glycol 400 as the precipitant. Diffraction was observed to a resolution of at least 1.9 A, and the evaluation of self-rotation functions confirmed 222 (D2) molecular symmetry.     

Elimination of polychlorinated dibenzofurans (PCDFs) and polychlorinated biphenyls (PCBs) from human blood in the Yusho and Yu-Cheng rice oil poisonings

The pharmacokinetics of polychlorinated dibenzofurans (PCDFs) and polychlorinated biphenyls (PCBs) in humans was studied by monitoring the blood concentrations of individuals who ingested a contaminated rice oil in Japan (yusho) in 1968 and in Taiwan (yu-cheng) in 1979. Sixteen yusho patients were followed from 1982 to 1990 and three yu-cheng individuals from 1980 to 1989. From the three yu-cheng patients, blood lipid values for the two persistent toxic congeners, 2,3,4,7,8-pentachlorodibenzofuran (PnCDF) and 1,2,3,4,7,8-hexachlorodibenzofuran (HxCDF), varied from 50 micrograms/kg at first sampling to about 1 micrograms/kg at last sampling corresponding to half-lives for elimination (t1/2) of 2-21/2 years. The blood lipid values for the same PCDF congeners in yusho patients varied from 5 micrograms/kg down to 0.1 micrograms/kg. The calculated t1/2 were more variable with median values closer to 10 years. Planar PCBs #126 and #169 were present at lower concentrations than the PCDFs. For seven of the other PCB congeners, half-lives for elimination in the yu-cheng individuals varied from 1.2 up to 4.6 yr depending on the degree of chlorination. For the yusho patients, the elimination for the PCBs was longer. These results show that clearance of the toxic PCDFs and PCBs in humans is non-linear with faster elimination at higher exposure followed by slower decreases as background levels are approached. Such a clearance pattern can best be explained by a two compartment liver and fat pharmacokinetic model.     

Chemistry of denitrification in sporogenous soil bacteria

Soil sporeforming denitrifying bacteria, Bacillus filaris and Bacillus polymyxa, differ by their cultural-morphological and physiological characteristics, but are similar in the chemistry of dissimilating nitrate reduction. Two processes occur simultaneously: denitrification yielding gaseous nitrogen forms, and nitrate respiration upon which nitrates are reduced to ammonia. The ratio between the two depends on physico-chemical conditions of the environment. The chemistry of dissimilating nitrate reduction by sporeforming bacteria differs therefore from nitrate transformation by other denitrifying microorganisms: Pseudomonas, Micrococcus, Rhizobium, Achromobacter, which, according to the published evidence, are capable only of denitrification.