Because of the long half-life of lead stored in bone (years), skeletal lead stores may be a source of endogenous lead exposure during periods of increased bone demineralization, such as menopause. To ...test the hypothesis that postmenopausal bone resorption increases blood lead levels, the authors examined cross-sectional associations of bone density-related factors with blood lead levels among women aged 40-59 years from the Third National Health and Nutrition Examination Survey (1988-1994). Factors related to bone turnover were significant predictors of blood lead level. Bone mineral density was significantly inversely related to blood lead levels in log-linear multivariate models that adjusted for age, race/ethnicity, smoking, education, household income, alcohol use, and residence (urban/rural). With menopausal status added to the model, naturally and surgically menopausal women had adjusted median blood lead levels that were 25% and 30% higher, respectively, than those of premenopausal women (2.0 microg/dl). Current use of hormone replacement therapy was associated with significantly lower adjusted median blood lead levels (1.8 microg/dl) than past use (2.6 microg/dl) and never use (2.2 microg/dl). Lead stored in bone may significantly increase blood lead levels in perimenopausal women because of postmenopausal bone mineral resorption. Attention to factors that prevent bone loss may lessen or prevent this endogenous lead exposure.
Background: Lead exposure is associated with elevated blood pressure during pregnancy; however, the magnitude of this relationship at low exposure levels is unclear. Objectives: Our goal was to ...determine the association between low-level lead exposure and blood pressure during late pregnancy. Methods: We collected admission and maximum (based on systolic) blood pressures during labor and delivery among 285 women in Baltimore, Maryland. We measured umbilical cord blood lead using inductively coupled plasma mass spectrometry. Multivariable models were adjusted for age, race, median household income, parity, smoking during pregnancy, prepregnancy body mass index, and anemia. These models were used to calculate benchmark dose values. Results: Geometric mean cord blood lead was 0.66 μg/dL (95% confidence interval, 0.61-0.70). Comparing blood pressure measurements between those in the highest and those in the lowest quartile of lead exposure, we observed a 6.87-mmHg (1.51-12.21 mmHg) increase in admission systolic blood pressure and a 4.40-mmHg (0.21— 8.59 mmHg) increase in admission diastolic blood pressure after adjustment for confounders. Corresponding values for maximum blood pressure increase were 7.72 (1.83-13.60) and 8.33 (1.14-15.53) mmHg. Benchmark dose lower limit values for a 1-SD increase in blood pressure were < 2 μg/dL blood lead for all blood pressure end points. Conclusions: A significant association between low-level lead exposures and elevations in maternal blood pressure during labor and delivery can be observed at umbilical blood lead levels < 2 μg/dL.
Inorganic arsenic is methylated in the body by arsenic (III) methyltransferase (AS3MT
)
. Arsenic methylation is thought to play a role in arsenic-related epigenetic phenomena, including aberrant DNA ...and histone methylation. However, it is unclear whether the promoter of the
AS3MT
gene, which codes for
AS3MT
, is differentially methylated as a function of arsenic exposure. In this study, we evaluated
AS3MT
promoter methylation according to exposure, assessed by urinary arsenic excretion in a stratified random sample of 48 participants from the Strong Heart Study who had urine arsenic measured at baseline and DNA available from 1989 to 1991 and 1998–1999. For this study, all data are from the 1989–1991 visit. We measured
AS3MT
promoter methylation at its 48 CpG loci by bisulphite sequencing. We compared mean % methylation at each CpG locus by arsenic exposure group using linear regression adjusted for study centre, age and sex. A hypomethylated region in the
AS3MT
promoter was associated with higher arsenic exposure. In vitro, arsenic induced
AS3MT
promoter hypomethylation, and it increased
AS3MT
expression in human peripheral blood mononuclear cells. These findings may suggest that arsenic exposure influences the epigenetic regulation of a major arsenic metabolism gene.
Limited data suggest that lead (Pb), cadmium (Cd), and uranium (U) may disrupt vitamin D metabolism and inhibit production of 1,25-dihydroxyvitamin D 1,25(OH)2D, the active vitamin D metabolite, from ...25-hydroxyvitamin D 25(OH)D in the kidney.
We evaluated the association between blood lead (BPb) and urine arsenic (As), Cd, molybdenum (Mo), thallium (Tl), and U with markers of vitamin D metabolism 25(OH)D and 1,25(OH)2D.
We conducted a cross-sectional study of 512 adolescents in Torreón, a town in Mexico with a Pb smelter near residential areas. BPb was measured using atomic absorption spectrometry. Urine As, Cd, Mo, Tl, and U were measured using inductively coupled plasma mass spectrometry. Serum 25(OH)D and 1,25(OH)2D were measured using a chemiluminescent immunoassay and a radioimmunoassay, respectively. Multivariable linear models with vitamin D markers as the outcome were used to estimate associations of BPb and creatinine-corrected urine As and metal concentrations with serum vitamin D concentrations, controlling for age, sex, adiposity, smoking, socioeconomic status, and time outdoors.
Serum 25(OH)D was positively associated with urine Mo and Tl 1.5 (95% CI: 0.4, 2.6) and 1.2 (95% CI: 0.3, 2.1) ng/mL higher with a doubling of exposure, respectively. Serum 1,25(OH)2D was positively associated with urine As and U 3.4 (95% CI: 0.9, 5.9) and 2.2 (95% CI: 0.7, 3.7) pg/mL higher, respectively, with little change in associations after additional adjustment for serum 25(OH)D. Pb and Cd were not associated with 25(OH)D or 1,25(OH)2D concentrations.
Overall, our findings did not support a negative effect of As or metal exposures on serum 1,25(OH)2D concentrations. Additional research is needed to confirm positive associations between serum 1,25(OH)2D and urine U and As concentrations and to clarify potential underlying mechanisms.
This article reviews the evidence concerning the emergence of community-acquired MRSA and highlights the relevance of reservoirs of antimicrobial resistance in humans and animals in the community ...environment. Although hospital use of antimicrobials has been assumed to generate the highest risk of resistance and transmission of resistant infections, the greater load of antimicrobial use is found in food animal production. The authors conclude that it is important to assess accurately and evaluate the interactions between hospital and community; improve surveillance for resistance of community origin, including agriculture; and to implement policies that prevent increases in community reservoirs of antibiotic resistance.
The stability of the
populations in the human gastrointestinal tract is not fully appreciated, and represents a significant knowledge gap regarding gastrointestinal community structure, as well as ...resistance to incoming pathogenic bacterial species and antibiotic treatment. The current study examines the genomic content of 240
isolates from 30 children, aged 2 to 35 months old, in Tanzania. The
strains were isolated from three time points spanning a six-month time period, with and without antibiotic treatment. The resulting isolates were sequenced, and the genomes compared. The findings in this study highlight the transient nature of
strains in the gastrointestinal tract of these children, as during a six-month interval, no one individual contained phylogenomically related isolates at all three time points. While the majority of the isolates at any one time point were phylogenomically similar, most individuals did not contain phylogenomically similar isolates at more than two time points. Examination of global genome content, canonical
virulence factors, multilocus sequence type, serotype, and antimicrobial resistance genes identified diversity even among phylogenomically similar strains. There was no apparent increase in the antimicrobial resistance gene content after antibiotic treatment. The examination of the
from longitudinal samples from multiple children in Tanzania provides insight into the genomic diversity and population variability of resident
within the rapidly changing environment of the gastrointestinal tract of these children.
This study increases the number of resident
genome sequences, and explores
diversity through longitudinal sampling. We investigate the genomes of
isolated from human gastrointestinal tracts as part of an antibiotic treatment program among rural Tanzanian children. Phylogenomics demonstrates that resident
are diverse, even within a single host. Though the
isolates of the gastrointestinal community tend to be phylogenomically similar at a given time, they differed across the interrogated time points, demonstrating the variability of the members of the
community in these subjects. Exposure to antibiotic treatment did not have an apparent impact on the
community or the presence of resistance and virulence genes within
genomes. The findings of this study highlight the variable nature of specific bacterial members of the human gastrointestinal tract.
Workers in poultry processing and pork meatpacking have high rates of acute injuries and chronic disease among. The presence of zoonotic pathogens in these workplaces may interact with injury.
We ...investigated incidence of worker injuries, lacerations, and infections reported by 10 companies from 2004 to 2009 and calculated annual incidence rates by industry and company along with temporal trends and job-related risk factors.
Average annual mean total injury rates were 6.4 per 100 workers (poultry) and 13.2 per 100 workers (pork). Average annual mean rates for lacerations were 1.8 per 100 workers (poultry) and 1.9 per 100 (pork). Sharp tools and animal products were most frequently reported as sources for lacerations. Animal products were most frequently reported as sources of infected lacerations.
The results indicate that these industries continue to have high injury rates. The results also suggest that zoonotic pathogens may be preventable health and safety risks.
High blood lead (BPb) levels in children and elevated soil and dust arsenic, cadmium, and lead were previously found in Torreón, northern Mexico, host to the world's fourth largest lead-zinc metal ...smelter. The objectives of this study were to determine spatial distributions of adolescents with higher BPb and creatinine-corrected urine total arsenic, cadmium, molybdenum, thallium, and uranium around the smelter. Cross-sectional study of 512 male and female subjects 12-15 years of age was conducted. We measured BPb by graphite furnace atomic absorption spectrometry and urine trace elements by inductively coupled plasma-mass spectrometry, with dynamic reaction cell mode for arsenic. We constructed multiple regression models including sociodemographic variables and adjusted for subject residence spatial correlation with spatial lag or error terms. We applied local indicators of spatial association statistics to model residuals to identify hot spots of significant spatial clusters of subjects with higher trace elements. We found spatial clusters of subjects with elevated BPb (range 3.6-14.7 μg/dl) and urine cadmium (0.18-1.14 μg/g creatinine) adjacent to and downwind of the smelter and elevated urine thallium (0.28-0.93 μg/g creatinine) and uranium (0.07-0.13 μg/g creatinine) near ore transport routes, former waste, and industrial discharge sites. The conclusion derived from this study was that spatial clustering of adolescents with high BPb and urine cadmium adjacent to and downwind of the smelter and residual waste pile, areas identified over a decade ago with high lead and cadmium in soil and dust, suggests that past and/or present plant operations continue to present health risks to children in those neighborhoods.
Campylobacteriosis is the most common antecedent infection leading to the development of inflammatory neuropathies including Guillain Barré syndrome (GBS) and Miller Fisher syndrome (MFS), with ...alterations in surface proteins and genetic polymorphisms conferring increased risk. Poultry is the most common source of
C. jejuni infection in industrialized countries, including the US. There are no data on the prevalence on consumer poultry products of various strains of
C. jejuni, including those hypothesized to be associated with neuropathy.
To study this,
C. jejuni was isolated from fresh broiler chicken products purchased from grocery stores in the Baltimore area. LOS subtypes and specific genetic polymorphisms were determined by PCR and DNA sequencing. The observed relative proportions of LOS subtypes and genetic polymorphisms in the
cstII gene (encoding bacterial sialyltransferases involved in LOS synthesis in
C. jejuni) were characterized and compared to those reported in published studies of patients with GBS, MFS and uncomplicated enteritis.
Commercial poultry products carry a relatively high prevalence of
C. jejuni strains that have been associated with neuropathic sequelae. The relative proportions of LOS classes in poultry isolates were similar to those reported in isolates from human enteritis cases, and in some instances also similar to isolates from patients diagnosed with neuropathic disease. In terms of
cstII polymorphisms, there were also similarities between isolates from poultry and those from patients with GBS and MFS.
► Infections by
Camylobacter jejuni are a major antecedent risk factor for inflammatory peripheral neuropathies. ►Analysis of an archive of
C. jejuni isolated from consumer poultry products indicates a high prevalence of neuropathic strains of this bacterium. ►Consumers are known to be at risk of exposure to
C. jejuni; others in contact with poultry may also experience elevated risks.
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