Comparison of questionnaire-based estimation of pesticide residue intake from fruits and vegetables with urinary concentrations of pesticide biomarkers

We developed a pesticide residue burden score (PRBS) based on a food frequency questionnaire and surveillance data on food pesticide residues to characterize dietary exposure over the past year. In the present study, we evaluated the association of the PRBS with urinary concentrations of pesticide biomarkers. Fruit and vegetable (FV) intake was classified as having high (PRBS≥4) or low (PRBS<4) pesticide residues for 90 men from the EARTH study. Two urine samples per man were analyzed for seven biomarkers of organophosphate and pyrethroid insecticides, and the herbicide 2,4-dichlorophenoxyacetic acid. We used generalized estimating equations to analyze the association of the PRBS with urinary concentrations of pesticide biomarkers. Urinary concentrations of pesticide biomarkers were positively related to high pesticide FV intake but inversely related to low pesticide FV intake. The molar sum of urinary concentrations of pesticide biomarkers was 21% (95% confidence interval (CI): 2%, 44%) higher for each one serving/day increase in high pesticide FV intake, and 10% (95% CI: 1%, 18%) lower for each one serving/day increase in low pesticide FV intake. Furthermore, intake of high pesticide FVs positively related to most individual urinary biomarkers. Our findings support the usefulness of the PRBS approach to characterize dietary exposure to select pesticides.

Infant Nutritional Status and Markers of Environmental Enteric Dysfunction are Associated with Midchildhood Anthropometry and Blood Pressure in Tanzania

OBJECTIVE

To assess whether growth and biomarkers of environmental enteric dysfunction in infancy are related to health outcomes in midchildhood in Tanzania.

STUDY DESIGN

Children who participated in 2 randomized trials of micronutrient supplements in infancy were followed up in midchildhood (4.6-9.8 years of age). Anthropometry was measured at age 6 and 52 weeks in both trials, and blood samples were available from children at 6 weeks and 6 months from 1 trial. Linear regression was used for height-for-age z-score, body mass index-for-age z-score, and weight for age z-score, and blood pressure analyses; log-binomial models were used to estimate risk of overweight, obesity, and stunting in midchildhood.

RESULTS

One hundred thirteen children were followed-up. Length-for-age z-score at 6 weeks and delta length-for-age z-score from 6 to 52 weeks were associated independently and positively with height-for-age z-score and inversely associated with stunting in midchildhood. Delta weight-for-length and weight-for-age z-score were also positively associated with midchildhood height-for-age z-score. The 6-week and delta weight-for-length z-scores were associated independently and positively with midchildhood body mass index-for-age z-score and overweight, as was the 6-week and delta weight-for-age z-score. Delta length-for-age z-score was also associated with an increased risk of overweight in midchildhood. Body mass index-for-age z-score in midchildhood was associated positively with systolic blood pressure. Serum anti-flagellin IgA concentration at 6 weeks was also associated with increased blood pressure in midchildhood.

CONCLUSIONS

Anthropometry at 6 weeks and growth in infancy independently predict size in midchildhood, while anti-flagellin IgA, a biomarker of environmental enteric dysfunction, in early infancy is associated with increased blood pressure in midchildhood. Interventions in early life should focus on optimizing linear growth while minimizing excess weight gain and environmental enteric dysfunction.

TRIAL REGISTRATION

ClinicalTrials.gov: NCT00197730 and NCT00421668.

A Method to Exploit the Structure of Genetic Ancestry Space to Enhance Case-Control Studies

One goal of human genetics is to understand the genetic basis of disease, a challenge for diseases of complex inheritance because risk alleles are few relative to the vast set of benign variants. Risk variants are often sought by association studies in which allele frequencies in case subjects are contrasted with those from population-based samples used as control subjects. In an ideal world we would know population-level allele frequencies, releasing researchers to focus on case subjects. We argue this ideal is possible, at least theoretically, and we outline a path to achieving it in reality. If such a resource were to exist, it would yield ample savings and would facilitate the effective use of data repositories by removing administrative and technical barriers. We call this concept the Universal Control Repository Network (UNICORN), a means to perform association analyses without necessitating direct access to individual-level control data. Our approach to UNICORN uses existing genetic resources and various statistical tools to analyze these data, including hierarchical clustering with spectral analysis of ancestry; and empirical Bayesian analysis along with Gaussian spatial processes to estimate ancestry-specific allele frequencies. We demonstrate our approach using tens of thousands of control subjects from studies of Crohn disease, showing how it controls false positives, provides power similar to that achieved when all control data are directly accessible, and enhances power when control data are limiting or even imperfectly matched ancestrally. These results highlight how UNICORN can enable reliable, powerful, and convenient genetic association analyses without access to the individual-level data.

Screening for Chronic Obstructive Pulmonary Disease: US Preventive Services Task Force Recommendation Statement

IMPORTANCE

About 14% of US adults aged 40 to 79 years have chronic obstructive pulmonary disease (COPD), and it is the third leading cause of death in the United States. Persons with severe COPD are often unable to participate in normal physical activity due to deterioration of lung function.

OBJECTIVE

To update the 2008 US Preventive Services Task Force (USPSTF) recommendation on screening for COPD in asymptomatic adults.

EVIDENCE REVIEW

The USPSTF reviewed the evidence on whether screening for COPD in asymptomatic adults (those who do not recognize or report respiratory symptoms) improves health outcomes. The USPSTF reviewed the diagnostic accuracy of screening tools (including prescreening questionnaires and spirometry); whether screening for COPD improves the delivery and uptake of targeted preventive services, such as smoking cessation or relevant immunizations; and the possible harms of screening for and treatment of mild to moderate COPD.

FINDINGS

Similar to 2008, the USPSTF did not find evidence that screening for COPD in asymptomatic persons improves health-related quality of life, morbidity, or mortality. The USPSTF determined that early detection of COPD, before the development of symptoms, does not alter the course of the disease or improve patient outcomes. The USPSTF concludes with moderate certainty that screening for COPD in asymptomatic persons has no net benefit.

CONCLUSIONS AND RECOMMENDATION

The USPSTF recommends against screening for COPD in asymptomatic adults. (D recommendation).

Screening for Impaired Visual Acuity in Older Adults: US Preventive Services Task Force Recommendation Statement

DESCRIPTION

Update of the US Preventive Services Task Force (USPSTF) recommendation on screening for impaired visual acuity in older adults.

METHODS

The USPSTF reviewed the evidence on screening for visual acuity impairment associated with uncorrected refractive error, cataracts, and age-related macular degeneration among adults 65 years or older in the primary care setting; the benefits and harms of screening; the accuracy of screening; and the benefits and harms of treatment of early vision impairment due to uncorrected refractive error, cataracts, and age-related macular degeneration.

POPULATION

This recommendation applies to asymptomatic adults 65 years or older who do not present to their primary care clinician with vision problems.

RECOMMENDATION

The USPSTF concludes that the current evidence is insufficient to assess the balance of benefits and harms of screening for impaired visual acuity in older adults. (I statement).

Screening for Autism Spectrum Disorder in Young Children: US Preventive Services Task Force Recommendation Statement

DESCRIPTION

New US Preventive Services Task Force (USPSTF) recommendation on screening for autism spectrum disorder (ASD) in young children.

METHODS

The USPSTF reviewed the evidence on the accuracy, benefits, and potential harms of brief, formal screening instruments for ASD administered during routine primary care visits and the benefits and potential harms of early behavioral treatment for young children identified with ASD through screening.

POPULATION

This recommendation applies to children aged 18 to 30 months who have not been diagnosed with ASD or developmental delay and for whom no concerns of ASD have been raised by parents, other caregivers, or health care professionals.

RECOMMENDATION

The USPSTF concludes that the current evidence is insufficient to assess the balance of benefits and harms of screening for ASD in young children for whom no concerns of ASD have been raised by their parents or a clinician. (I statement).

Screening for Depression in Adults: US Preventive Services Task Force Recommendation Statement

DESCRIPTION

Update of the 2009 US Preventive Services Task Force (USPSTF) recommendation on screening for depression in adults.

METHODS

The USPSTF reviewed the evidence on the benefits and harms of screening for depression in adult populations, including older adults and pregnant and postpartum women; the accuracy of depression screening instruments; and the benefits and harms of depression treatment in these populations.

POPULATION

This recommendation applies to adults 18 years and older.

RECOMMENDATION

The USPSTF recommends screening for depression in the general adult population, including pregnant and postpartum women. Screening should be implemented with adequate systems in place to ensure accurate diagnosis, effective treatment, and appropriate follow-up. (B recommendation).

Developmental determinants in non-communicable chronic diseases and ageing

Prenatal and peri-natal events play a fundamental role in health, development of diseases and ageing (Developmental Origins of Health and Disease (DOHaD)). Research on the determinants of active and healthy ageing is a priority to: (i) inform strategies for reducing societal and individual costs of an ageing population and (ii) develop effective novel prevention strategies. It is important to compare the trajectories of respiratory diseases with those of other chronic diseases.

Genome-wide association analysis identifies 13 new risk loci for schizophrenia

Schizophrenia is a heritable disorder with substantial public health impact. We conducted a multi-stage genome-wide association study (GWAS) for schizophrenia beginning with a Swedish national sample (5,001 cases, 6,243 controls) followed by meta-analysis with prior schizophrenia GWAS (8,832 cases, 12,067 controls) and finally by replication of SNPs in 168 genomic regions in independent samples (7,413 cases, 19,762 controls, and 581 trios). In total, 22 regions met genome-wide significance (14 novel and one previously implicated in bipolar disorder). The results strongly implicate calcium signaling in the etiology of schizophrenia, and include genome-wide significant results for CACNA1C and CACNB2 whose protein products interact. We estimate that ∼8,300 independent and predominantly common SNPs contribute to risk for schizophrenia and that these collectively account for most of its heritability. Common genetic variation plays an important role in the etiology of schizophrenia, and larger studies will allow more detailed understanding of this devastating disorder.

Racial discrimination, response to unfair treatment, and depressive symptoms among pregnant black and African American women in the United States

PURPOSE

To assess the association between self-reported racial discrimination and prenatal depressive symptoms among black women.

METHODS

Our study population consisted of two cohorts of pregnant women: the Asthma Coalition on Community, Environment, and Social Stress project (ACCESS) and Project Viva. We measured self-reported racial discrimination among black women using a modified Experiences of Discrimination scale (score 0-8). We assessed elevated depressive symptoms (EDS) with the Edinburgh Postnatal Depression Scale (≥13 on a 0-30 scale).

RESULTS

Fifty-four percent of ACCESS and 78% of Viva participants reported experiencing racial discrimination. After adjusting for age, marital status, income, education, and nativity, a 1-U increment in Experiences of Discrimination score was associated with 48% increased odds of EDS (odds ratio, 1.48; 95% confidence interval, 1.24-1.76) for ACCESS participants but was not significantly associated among Viva participants (odds ratio, 1.12; 95% confidence interval, 0.92-1.37). In both cohorts, responding to unfair treatment by talking to others was associated with the lowest odds of EDS.

CONCLUSIONS

Our findings suggest that higher levels of perceived racial discrimination may increase depressive symptoms during pregnancy among U.S. black women. Interventions involving talking to others may aid in reducing the risk of depressive symptoms among black women experiencing higher levels of racial discrimination.

Gestational intake of methyl donors and global LINE-1 DNA methylation in maternal and cord blood: prospective results from a folate-replete population

Maternal diet affects offspring DNA methylation in animal models, but evidence from humans is limited. We investigated the extent to which gestational intake of methyl donor nutrients affects global DNA methylation in maternal and umbilical cord blood. Among mother-infant pairs in Project Viva, a folate-replete US population, we estimated maternal intakes of vitamin B12, betaine, choline, folate, cadmium, zinc and iron periconceptionally and during the second trimester. We examined associations of these nutrients with DNA methylation, measured as %5-methyl cytosines (%5mC) in Long Interspersed Nuclear Element-1 (LINE-1), in first trimester (n = 830) and second trimester (n = 671) maternal blood and in cord blood at delivery (n = 516). Cord blood methylation was higher for male than female infants {mean [standard deviation (SD)] 84.8 [0.6] vs. 84.4 [0.7]%}. In the multivariable-adjusted model, maternal intake of methyl donor nutrients periconceptionally and during the second trimester of pregnancy was not positively associated with first trimester, second trimester or cord blood LINE-1 methylation. Periconceptional betaine intake was inversely associated with cord blood methylation [regression coefficient = -0.08% (95% confidence interval (CI): -0.14,-0.01)] but this association was attenuated after adjustment for dietary cadmium, which itself was directly associated with first trimester methylation and inversely associated with cord blood methylation. We also found an inverse association between periconceptional choline [-0.10%, 95% CI: -0.17,-0.03 for each SD (~63 mg/day)] and cord blood methylation in males only. In this folate-replete population, we did not find positive associations between intake of methyl donor nutrients during pregnancy and DNA methylation overall, but among males, higher early pregnancy intakes of choline were associated with lower cord blood methylation.

Interaction between ERAP1 and HLA-B27 in ankylosing spondylitis implicates peptide handling in the mechanism for HLA-B27 in disease susceptibility

Ankylosing spondylitis is a common form of inflammatory arthritis predominantly affecting the spine and pelvis that occurs in approximately 5 out of 1,000 adults of European descent. Here we report the identification of three variants in the RUNX3, LTBR-TNFRSF1A and IL12B regions convincingly associated with ankylosing spondylitis (P < 5 × 10(-8) in the combined discovery and replication datasets) and a further four loci at PTGER4, TBKBP1, ANTXR2 and CARD9 that show strong association across all our datasets (P < 5 × 10(-6) overall, with support in each of the three datasets studied). We also show that polymorphisms of ERAP1, which encodes an endoplasmic reticulum aminopeptidase involved in peptide trimming before HLA class I presentation, only affect ankylosing spondylitis risk in HLA-B27-positive individuals. These findings provide strong evidence that HLA-B27 operates in ankylosing spondylitis through a mechanism involving aberrant processing of antigenic peptides.

The Early Determinants of Adult Health Study

This issue of the Journal features collaborative follow-up studies of two unique pregnancy cohorts recruited during 1959-1966 in the United States. Here we introduce the Early Determinants of Adult Health (EDAH) study. EDAH was designed to compare health outcomes in midlife (age 40s) for same-sex siblings discordant on birthweight for gestational age. A sufficient sample of discordant siblings could only be obtained by combining these two cohorts in a single follow-up study. All of the subsequent six papers are either based upon the EDAH sample or are related to it in various ways. For example, three papers report results from studies that significantly extended the 'core' EDAH sample to address specific questions. We first present the overall design of and rationale for the EDAH study. Then we offer a synopsis of past work with the two cohorts to provide a context for both EDAH and the related studies. Next, we describe the recruitment and assessment procedures for the core EDAH sample. This includes the process of sampling and recruitment of potential participants; a comparison of those who were assessed and not assessed based on archived data; the methods used in the adult follow-up assessment; and the characteristics at follow-up of those who were assessed. We provide online supplementary tables with much further detail. Finally, we note further work in progress on EDAH and related studies, and draw attention to the broader implications of this endeavor.

Environment and Obesity in the National Children's Study

We describe the approach taken by the National Children's Study (NCS) to understanding the role of environmental factors in the development of obesity. We review the literature with regard to the two core hypotheses in the NCS that relate to environmental origins of obesity and describe strategies that will be used to test each hypothesis. Although it is clear that obesity in an individual results from an imbalance between energy intake and expenditure, control of the obesity epidemic will require understanding of factors in the modern built environment and chemical exposures that may have the capacity to disrupt the link between energy intake and expenditure. Through its embrace of the life-course approach to epidemiology, the NCS will be able to study the origins of obesity from preconception through late adolescence, including factors ranging from genetic inheritance to individual behaviors to the social, built, and natural environment and chemical exposures. It will have sufficient statistical power to examine interactions among these multiple influences, including geneenvironment and geneobesity interactions. A major secondary benefit will derive from the banking of specimens for future analysis.

DSP toxin profile in the coastal waters of the central Adriatic Sea

A monitoring program, carried out in 1996 and 1997, has confirmed that toxic compounds, other than the most frequently detected toxins okadaic acid (OA) and dinophysistoxin-1 (DTX-1), are involved in DSP phenomena in the Adriatic Sea. Toxicity was assessed by the mouse bioassay; the content and the nature of the toxic components were established through fluorometric HPLC analysis combined with mass spectrometry. A rare pectenotoxin-2 (PTX-2) derivative, 7-epi-pectenotoxin-2 seco acid (7-epi-PTX-2SA), was the exclusive contaminant of samples collected from the central Adriatic in 1996. Contrary to its marked oral toxicity, intraperitoneally 7-epi-PTX-2SA displayed no toxic effects, hampering its detection by the mouse bioassay. In 1997, its concentration and frequency of appearance were lower than in 1996, with concomitant occurrence of OA, DTX-2, and a new unidentified component related to the DSP toxic group of compounds. This is the first report on the occurrence of DTX-2 in Adriatic mussels. A survey of the phytoplankton community in the surrounding seawater has established the presence of Prorocentrum micans and several potentially toxic species from the Dinophysis genus. A case of unexplained toxicity, associated with the occurrence of Gonyaulax polyedra, suggested possible shellfish contamination with yessotoxin (YTX).

Determination of domoic acid in shellfish by liquid chromatography with electrospray ionization and multiple tandem mass spectrometry

Amnesic shellfish poisoning is a potentially lethal human toxic syndrome which is caused by domoic acid (DA) that originates in marine phytoplankton belonging to the Pseudonitzschia genus. A new sensitive liquid chromatographic-mass spectrometry (LC-MS) method has been developed for the determination of DA in various marine biological samples. The characteristic fragmentation pathways for DA were established using multiple stage MS on selected daughter ions, which were sequentially trapped and fragmented. Chromatography was performed using a gradient of acetonitrile-water (5:95 to 40:60), containing trifluoroacetic acid (0.05%), over 25 min at 0.2 ml/min with a C18 column (Luna-2, 150 x 2.0 mm, 5 microm). Using electrospray ionisation, multiple tandem MS experiments were performed with an ion-trap mass spectrometer (Finnigan MAT LCQ). The protonated DA molecule was the precursor ion, m/z 312, and the relative collision energies were optimised for multiple MS (MS(n), n = 2-4) studies. LC-MS3 using the ions, m/z 266 and 220, from the loss of two HCOOH molecules, produced the best sensitivity data. Calibration data for various MS modes were: MS (0.05-10 microg DA/ml, r2 = 0.9973); MS2 (0.025-10 microg DA/ml, r2=0.9997); MS3 (0.025-10 microg DA/ml, 0.9994). The detection limits (3:1 signal:noise) were better than 0.02 microg DA/ml for LC-MS, 0.014 microg DA/ml for LC-MS2 and 0.008 microg DA/ml for LC-MS3. This method was applied to determine DA in scallop (Pecten maximus) tissues, which subsequently led to the closure of several shellfish harvesting sites on the west coast of Ireland.

Maternal experiences of racism and violence as predictors of preterm birth: rationale and study design

Chronic psychological stress may raise the risk of preterm delivery by raising levels of placental corticotropin-releasing hormone (CRH). Women who have been the targets of racism or personal violence may be at particularly high risk of preterm delivery. The aims of this study are to examine the extent to which: (1) maternal experiences of racism or violence in childhood, adulthood, or pregnancy are associated with the risk of preterm birth; (2) CRH levels are prospectively associated with risk of preterm birth; and (3) CRH levels are associated with past and current maternal experiences of racism or violence. We have begun to examine these questions among women enrolled in Project Viva, a Boston-based longitudinal study of 6000 pregnant women and their children.

The occurrence of 7-epi-pectenotoxin-2 seco acid in the coastal waters of the central Adriatic (Kastela Bay)

Okadaic acid (OA) and 7-epi-pectenotoxin-2 seco acid (7-epi-PTX-2SA) were identified as the toxic determinants in mussels from the central Adriatic Sea. The nature of the pectenotoxin-2 derivative was confirmed by chromatographic comparison with toxins present in algae extracts of Dinophysis acuta from Ireland, and by mass spectrometric analysis. The origin of shellfish toxicity has been associated with the occurrence of the Dinophysis species. This is the first report on the incidence of 7-epi-PTX-2SA in the Adriatic region.

New fluorimetric method of liquid chromatography for the determination of the neurotoxin domoic acid in seafood and marine phytoplankton

Domoic acid (DA) is a neurotoxic amino acid that is responsible for the human toxic syndrome, amnesic shellfish poisoning (ASP). A new rapid, sensitive liquid chromatographic (LC) method has been developed for the determination of DA in various marine samples. DA in marine biological materials was derivatised with 4-fluoro-7-nitro-2,1,3-benzoxadiazole (NBD-F) and analysed using isocratic reversed-phase LC with fluorimetric detection. The calibration, based on standard DA solutions, was linear in the range 0.04-2 microg/ml (r2=0.998) and the detection limit (3:1, signal/noise) was better than 1 ng/ml. Using the certified reference material (MUS-1B), recoveries of DA from shellfish tissue were >95% (n=5). When a strong anion exchange SPE cartridge was used for sample clean-up the detection limit was 6 ng DA/g mussel tissue. Good reproducibility was achieved with RSD values ranging from 3% for 8 microg DA/g (n=5), to 5% for 0.04 microg DA/g (n=5). This new method was successfully applied to the determination of DA in naturally contaminated shellfish and in marine phytoplankton cultures of Pseudonitzschia sp.

Birth weight and length as predictors for adult height

Adult height has been found to be inversely associated with mortality. Recently, it has been suggested that growth in utero is linked with adult risk of several chronic diseases. The authors examined possible associations between birth weight, birth length, and adult height in young Danish men. They conducted the study in the fifth conscription district of Denmark including all the men born after January 1, 1973 who were residents in the study area during the period August 1, 1993 to July 31, 1994. The Danish Medical Birth Register contains information on all births in Denmark since January 1, 1973. Data on height from the Conscription Register were linked to the Danish Medical Birth Register in 4,300 conscripts examined. Nearly all Danish men have to register with the draft board around age 18 years of age where they undergo a physical examination. There was a strong positive association between birth weight and adult height; for subjects with birth weight < or = 2,500 g, mean height was 175.7 cm, while for those with birth weight > or = 4,501 g, mean height was 184.1 cm. A positive association was also found between birth length and adult height. For subjects with birth length < 47 cm, mean adult height was 175.2 cm, increasing to 184.3 cm at birth length > 56 cm. The associations between birth length and adult height persisted after adjustment for birth weight, gestational age, and other confounders, while the associations between birth weight and adult height almost disappeared when adjusting for birth length and the same confounders. Genetic and/or environmental factors operating both during the pre- and postnatal period may be responsible for the association between birth length and adult height.

Determination of diarrheic shellfish toxins in mussels by microliquid chromatography-tandem mass spectrometry

A fast, sensitive, and specific procedure for determining toxins that cause diarrheic shellfish poisoning (DSP) using microliquid chromatography coupled with tandem mass spectrometry (micro-LC-MS-MS) is reported. The lipophylic polyether acidic toxins okadaic acid (OA), its isomer dinophysistoxin-2 (DTX-2), the 35-methylokadaic acid dinophysistoxin-1 (DTX-1), and the novel toxin dinophysistoxin-1B (DTX-2B; recently isolated from Irish mussels) were extracted from shellfish tissues with acetone and chromatographed by isocratic elution at 10 microL/min with CH3 CN-H2O, 80 + 20 (v/v), containing 0.1% trifluoroacetic acid, through a C18 reversed-phase column (1.0 mm id). The chromatograph is coupled via an ion spray interface to an atmospheric pressure ionization source. Collision-induced-dissociation (CID) ion mass spectra of the protonated molecule, [M + H]+, at m/z 805 for OA, DTX-2, and DTX-2B and at m/z 819 for DTX-1, were obtained in MS-MS experiments to identify 2 diagnostic fragment ions for each analyte that could be used for selected-reaction-monitoring (SRM) micro-LC-MS-MS analysis. The CID spectrum of DTX-2B confirmed it to be a new OA isomer, like DTX-2. Standard curves obtained by SRM micro-LC-MS-MS were linear (r2 > or = 0.9992) over the range 0.05-1.00 micrograms/mL (i.e., 0.10-2.00 micrograms toxin/g hepatopancreas), and a detection limit of 15 pg/injection was obtained for each DSP toxin. Average recoveries ranged from 95 to 101%, and coefficients of variation ranged from 1.8 to 3.4%. This novel SRM micro-LC-MS-MS method was used to confirm acidic DSP toxins in Irish and Italian toxic mussels. It offers a high degree of specificity because analyte confirmation is based on retention time, molecular weight, structural information obtained from the presence of 2 diagnostic fragments for each analyte, and ion ratios. OA was found in both Irish (< or = 0.7 micrograms/g hepatopancreas) and Italian (< or = 1.5 micrograms/g hepatopancreas) mussels. DTX-1 was found only in Italian mussels (< or = 0.3 micrograms/g hepatopancreas). DTX-2 (< or = 6.1 micrograms/g hepatopancreas) and DTX-2B (< or = 0.08 micrograms/hepatopancreas) were unique to Irish shellfish.

Short Communication - Continued increase in prevalence of obesity in Danish young men

BACKGROUND

Previous studies of Danish young men showed a steep increase of obesity since the birth years of the early 1940s with a levelling off in the 1950s.

OBJECTIVE

To study the current prevalence of obesity and its recent changes in Danish young men.

DESIGN

Cross-sectional study based on weight and height measured at the military board for the birth cohorts 1955, 1965 and 1973-75.

SUBJECTS

We obtained information from the old paper files comprising the two cohorts of men born in 1955 (6549 adults) and 1965 (6404 adults) and prospectively examined 4300 from the birth cohorts 1973-75 in a conscription district in Denmark during the period 1 August 1993 to 31 July 1994.

RESULTS

The prevalence of obesity (defined as body mass index (BMI) > or = 30 kg/m2) was 1.5% in 1955, 2.1% in 1965 and 4.6% in 1973-75 birth cohorts. The median BMI has increased during the period from 21.7-22.8 kg/m2.

CONCLUSION

Obesity is relatively common and has increased among Danish young men.

Effects of dissolved organic carbon and salinity on bioavailability of mercury

Hypotheses that dissolved organic carbon (DOC) and electrochemical charge affect the rate of methylmercury [CH3Hg(I)] synthesis by modulating the availability of ionic mercury [Hg(II)] to bacteria were tested by using a mer-lux bioindicator (O. Selifonova, R. Burlage, and T. Barkay, Appl. Environ. Microbiol. 59:3083-3090, 1993). A decline in Hg(II)-dependent light production was observed in the presence of increasing concentrations of DOC, and this decline was more pronounced at pH 7 than at pH 5, suggesting that DOC is a factor controlling the bioavailability of Hg(II). A thermodynamic model (MINTEQA2) was used to select assay conditions that clearly distinguished among various Hg(II) species. By using this approach, it was shown that negatively charged forms of mercuric chloride (HgCl3-/HgCl(4)2-) induced less light production than the electrochemically neutral form (HgCl2), and no difference was observed between the two neutral forms, HgCl2 and Hg(OH)2. These results suggest that the negative charge of Hg(II) species reduces their availability to bacteria and may be one reason why accumulation of CH3Hg(I) is more often reported to occur in freshwater than in estuarine and marine biota.

Effects of dissolved organic carbon and salinity on bioavailability of mercury

Hypotheses that dissolved organic carbon (DOC) and electrochemical charge affect the rate of methylmercury [CH3Hg(I)] synthesis by modulating the availability of ionic mercury [Hg(II)] to bacteria were tested by using a mer-lux bioindicator (O. Selifonova, R. Burlage, and T. Barkay, Appl. Environ. Microbiol. 59:3083-3090, 1993). A decline in Hg(II)-dependent light production was observed in the presence of increasing concentrations of DOC, and this decline was more pronounced at pH 7 than at pH 5, suggesting that DOC is a factor controlling the bioavailability of Hg(II). A thermodynamic model (MINTEQA2) was used to select assay conditions that clearly distinguished among various Hg(II) species. By using this approach, it was shown that negatively charged forms of mercuric chloride (HgCl3-/HgCl(4)2-) induced less light production than the electrochemically neutral form (HgCl2), and no difference was observed between the two neutral forms, HgCl2 and Hg(OH)2. These results suggest that the negative charge of Hg(II) species reduces their availability to bacteria and may be one reason why accumulation of CH3Hg(I) is more often reported to occur in freshwater than in estuarine and marine biota.

Identification of a new diarrhoetic toxin in shellfish using liquid chromatography with fluorimetric and mass spectrometric detection

A new toxin, dinophysistoxin-2B (DTX-2B) was isolated from Irish mussels using silica chromatography, gel permeation, octadecylsilane solid-phase extraction and repeated preparative high-performance liquid chromatography (HPLC). Dinophysistoxin-2 (DTX-2) was also isolated from shellfish using the same procedures. The separation of these toxins in chromatographic fractions was monitored using fluorimetric HPLC following derivatization with 9-anthrylmethyldiazomethane or 1-bromoacetylpyrene. Flow-injection analysis-mass spectrometry (FIA-MS) with an atmospheric pressure ionization (API) and an ionspray (ISP) interface showed a mass spectrum dominated by the protonated molecule, [M+H]+, at m/z 805 for DTX-2B, thus indicating that this new toxin has the same mol.wt as okadaic acid and DTX-2. The low-energy fragment ion spectrum, as produced in FIA-MS experiments by up-front collision-induced dissociation of the protonated molecule of DTX-2B, showed fragment ions corresponding to successive losses of water molecules from the [M+H]+ ion. This low collision energy fragmentation pattern is typical of marine polyether toxins such as okadaic acid, DTX-2 and DTX-1. These results provide strong evidence that DTX-2B is another okadaic acid isomer.

Conjugal Gene Transfer to Aquatic Bacteria Detected by the Generation of a New Phenotype

An experimental approach based on the assembly of genes of a catabolic pathway was used to detect transconjugants in aquatic communities. Resistance to phenylmercury acetate was established in transconjugants when wide-host-range conjugal plasmids containing merB , the gene encoding organomercurial lyase, were transferred to strains from aquatic communities that had been acclimated to inorganic mercury and thus enriched for populations containing merA , the gene encoding mercuric reductase (T. Barkay, Appl. Environ. Microbiol. 53:2725-2732, 1987). Conjugation was confirmed by using the plasmids' encoded antibiotic resistance patterns and by hybridization with a eukaryotic gene. Three merB -conjugal plasmids, belonging to incompatibility groups W (pGTE16), P1 (pGTE26), and N (pGTE25), were prepared. Transfers by filter matings of pGTE16 and pGTE26 from Pseudomonas aeruginosa PA01 to indigenous strains were at efficiencies of 4.5 × 10 -2 and 4.8 × 10 -3 transconjugant per potential recipient, respectively. These efficiencies were from 1 to 2 orders of magnitude below those observed for intraspecies matings with genetically marked recipients. The third plasmid, pGTE25, was not stably maintained in P. aeruginosa donors, and its transfer from Escherichia coli donors was below the level of detection. Characterized transconjugant strains were shown to be Pseudomonas spp. Potential applications of the described experimental approach in the creation of bacterial populations with new catabolic capabilities in hazardous waste sites and in the detection of transfer of recombinant DNA from engineered microorganisms to indigenous bacteria are discussed.

Genes encoding mercuric reductases from selected gram-negative aquatic bacteria have a low degree of homology with merA of transposon Tn501

An investigation of the Hg2+ resistance mechanism of four freshwater and four coastal marine bacteria that did not hybridize with a mer operonic probe was conducted (T. Barkay, C. Liebert, and M. Gillman, Appl. Environ. Microbiol. 55:1196-1202, 1989). Hybridization with a merA probe, the gene encoding the mercuric reductase polypeptide, at a stringency of hybridization permitting hybrid formation between evolutionarily distant merA genes (as exists between gram-positive and -negative bacteria), detected merA sequences in the genomes of all tested strains. Inducible Hg2+ volatilization was demonstrated for all eight organisms, and NADPH-dependent mercuric reductase activities were detected in crude cell extracts of six of the strains. Because these strains represented random selections of bacteria from three aquatic environments, it is concluded that merA encodes a common molecular mechanism for Hg2+ resistance and volatilization in aerobic heterotrophic aquatic communities.

Hybridization of DNA probes with whole-community genome for detection of genes that encode microbial responses to pollutants: mer genes and Hg2+ resistance

Nucleic acids extracted from microbial biomass without prior culturing were hybridized with probes representing four mer operons to detect genes encoding adaptation to Hg2+ in whole-community genomes. A 29-fold enrichment in sequences similar to the mer genes of transposon Tn501 occurred during adaptation in a freshwater community. In an estuarine community, all four mer genes were only slightly enriched (by three- to fivefold), suggesting that additional, yet uncharacterized, mer genes encoded adaptation to Hg2+.

Environmental significance of the potential for mer(Tn21)-mediated reduction of Hg2+ to Hg0 in natural waters

The role of mer(Tn21) in the adaptation of aquatic microbial communities to Hg2+ was investigated. Elemental mercury was the sole product of Hg2+ volatilization by freshwater and saline water microbial communities. Bacterial activity was responsible for biotransformation because most microeucaryotes did not survive the exposure conditions, and removal of larger microbes (greater than 1 micromole) from adapted communities did not significantly (P greater than 0.01) reduce Hg2+ volatilization rates. DNA sequences homologous to mer(Tn21) were found in 50% of Hg2+-resistant bacterial strains representing two freshwater communities, but in only 12% of strains representing two saline communities (the difference was highly significant; P less than 0.001). Thus, mer(Tn21) played a significant role in Hg2+ resistance among strains isolated from fresh waters, in which microbial activity had a limited role in Hg2+ volatilization. In saline water environments in which microbially mediated volatilization was the major mechanism of Hg2+ loss, other bacterial genes coded for this biotransformation.

New vistas in chronic schizophrenia

In view of the distinct possibility that the disturbed glucose regulation in the frontal area and basal ganglia of chronic schizophrenia is very germane to the successful treatment of this condition, a survey is given of the many factors that have to be considered in developing a therapy that takes into account this new information. The suggestion is made that the balance between cAMP and cGMP in the cells affected are dysregulated so that there is an excessive activity of the cAMP generating system which eventually leads to the pathological picture found in this condition. To restore the normal metabolic balance, use will have to be made of the various substances that are known to enhance the cGMP generating system in the cell, thereby restoring a more normal metabolic integrity. In this connection, the use of high doses of insulin under cover of hyperglycaemia and also the addition of D-ribose could become the cornerstone of a series of treatments to enhance the action of currently used medications in this often intractable illness.