Understanding the biogeochemical cycling of mercury is critical for explaining the presence of mercury in remote regions of the world, such as the Arctic and the Himalayas, as well as local concentrations. While we have good knowledge of present-day fluxes of mercury to the atmosphere, we have little knowledge of what emission levels were like in the past. Here we develop a trend of anthropogenic emissions of mercury to the atmosphere from 1850 to 2008-for which relatively complete data are available-and supplement that trend with an estimate of anthropogenic emissions prior to 1850. Global mercury emissions peaked in 1890 at 2600 Mg yr(-1), fell to 700-800 Mg yr(-1) in the interwar years, then rose steadily after 1950 to present-day levels of 2000 Mg yr(-1). Our estimate for total mercury emissions from human activities over all time is 350 Gg, of which 39% was emitted before 1850 and 61% after 1850. Using an eight-compartment global box-model of mercury biogeochemical cycling, we show that these emission trends successfully reproduce present-day atmospheric enrichment in mercury.
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Consomic rats (SS.BN13), in which chromosome 13 from normotensive inbred Brown Norway rats from a colony maintained at the Medical College of Wisconsin (BN/Mcw) was introgressed into the background of Dahl salt-sensitive (SS/Mcw) rats, also maintained in a colony at the Medical College of Wisconsin, were bred. The present studies determined the mean arterial pressure (MAP) responses to salt and renal and peripheral vascular responses to norepinephrine and angiotensin II; 24-hour protein excretion and histological analyses were used to assess renal pathology in rats that received a high salt (4% NaCl) diet for 4 weeks. MAP of rats measured daily during the fourth week averaged 170+/-3.3 mm Hg in SS/Mcw rats, 119+/-2.1 mm Hg in SS.BN13 rats, and 103+/-1.3 mm Hg in BN/Mcw rats. After salt depletion, MAP fell an average of 27+/-4.5 mm Hg in SS/Mcw rats, 9+/-2.6 mm Hg in SS.BN13 rats, and 11+/-3.0 mm Hg in BN/Mcw rats. Protein excretion of SS/Mcw rats on a high salt diet averaged 189+/-30 mg/24 h, 63+/-18 mg/24 h in SS.BN13 rats, and 40+/-6.4 mg/24 h in BN/Mcw rats. Compared with SS.BN13 and BN/Mcw rats, SS/Mcw rats exhibited significantly greater increases of renal vascular resistance in response to intravenous norepinephrine and angiotensin II. Severe medullary interstitial fibrosis and tubular necrosis after a high salt diet were found consistently in SS/Mcw rat kidneys but were largely absent in the SS.BN13 and BN/Mcw rat kidneys. A similar degree of glomerular sclerosis was found in both SS/Mcw and SS.BN13 rats. In rats fed a 0.4% salt diet, the glomerular filtration rate of SS/Mcw rats was significantly less than that of BN/Mcw and SS.BN13 rats. These results reveal a powerful gene, or set of genes, within chromosome 13 of BN/Mcw rats that confers protection from the detrimental effects of high salt to the SS/Mcw rats.
OBJECTIVE: We evaluated the need for vigorous resuscitation (bag-and-mask ventilation, tracheal intubation, and cardiopulmonary resuscitation) in certain common cesarean deliveries at term to evaluate the need for pediatrician attendance on behalf of the fetus. METHODS: Records of singleton cesarean deliveries (repeat, nonprogressive labor, fetal malposition, fetal heart rate abnormality) at term over 2 years were reviewed for the following: need for vigorous resuscitation, Apgar scores, anesthesia used, and the need for newborn intensive care. The next consecutive, uncomplicated singleton vaginal delivery in each case was used to create a control group. Exclusion criteria included the presence of maternal disease (diabetes, pregnancy-induced hypertension, placenta previa) or suspicion of fetal abnormalities (growth restriction, congenital defect, known meconium staining of the amniotic fluid). There were 834 cesarean deliveries and 834 controls (low-risk vaginal deliveries). RESULTS: Compared with vaginal deliveries, Apgar scores of 6 or less at 1 minute were more frequent in all cesarean deliveries except for the repeat cesarean category. The incidence of needing vigorous resuscitation was as follows: vaginal 1.7%, repeat 3.0%, nonprogressive labor 4.8%, fetal malposition 11.2%, and fetal heart rate abnormality 17.7%. The use of regional anesthesia reduced the need for vigorous resuscitation in cesarean deliveries for the repeat group and the group with nonprogressive labor without fetal heart rate abnormalities to a level similar to that in uncomplicated vaginal deliveries (2.1% repeat; 1.6% nonprogressive labor without fetal heart rate abnormality). CONCLUSIONS: Both repeat cesarean deliveries and cesareans done for nonprogressive labor without signs of fetal heart rate abnormality, when performed under regional anesthesia, may not need a pediatrician in attendance because of minimal fetal risk.
Differences in serum glucose values obtained from different extremities in newborns with umbilical artery catheters (UAC) through which a dextrose solution was administered were studied. Control infants (n = 20) had no difference in simultaneous capillary glucose values obtained from both lower extremities. Infants with a low UAC had a significant difference between two (both lower extremities) or three (both lower and one upper extremity) simultaneous capillary glucose values. Infants with a high UAC did not. In the low UAC group, the serum glucose value was highest in the lower extremity through which the UAC entered the aorta and lowest in the upper extremity. The elevation in glucose value was related to the glucose infusion rate corrected for infant size (mg/kg/min). Clinicians caring for infants with low UACs should be aware of this potential error in order to prevent erroneous decision-making.
All records of primary liver cancer reported to the tumor registry of the Province of Québec from 1969 to 1972 were collected and were classified according to sex, age and place of residence. Men had higher incidence of primary liver cancer and the disease developed at an earlier age in men than it did in women. There was a noticeable difference in the number of cases in rural and urban areas, and a significant difference in the incidence in the 10 districts of the province. Cases in urban areas were clustered in a few industrialized cities. Our findings are in agreement with previous reports that show a relationship between primary cancer of the liver and the presence of chemicals in the environment.
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Chromosome 13 consomic and congenic rat strains were analyzed to investigate the pattern of genomic pathway utilization involved in protection against salt-sensitive hypertension and renal injury. Introgression of the entire Brown-Norway chromosome 13 (consomic SS-13(BN)) or nonoverlapping segments of this chromosome (congenic strains, 16 Mbp in D13Rat151-D13Rat197 or 14 Mbp in D13Rat111-D13Got22) into the genome of the Dahl salt-sensitive rat attenuated salt-induced hypertension and proteinuria. mRNA abundance profiles in the renal cortex and the renal medulla from rats receiving 0.4% or 8% NaCl diets revealed two important features of pathway recruitment in these rat strains. First, the two congenic strains shared alterations in several pathways compared with Dahl salt-sensitive rats, despite the fact that the genomic segments introgressed in the two congenic strains did not overlap. Second, even though the genomic segment introgressed in each congenic strain was a part of the chromosome introgressed in the consomic strain, pathways altered in each congenic strain were not simply a subset of those altered in the consomic. Supporting the relevance of the mRNA data, differential expression of oxidative stress-related genes among the four strains of rats was associated with differences in urinary excretion of lipid peroxidation products. The findings suggest that different genetic alterations might converge to influence shared pathways in protection from hypertension, and that, depending on the genomic context, the same genetic alteration might diverge to affect different pathways.
Using population-based health services information to estimate the effectiveness of colonoscopy on colorectal cancer (CRC) outcomes is prone to selection bias.
To determine the effect of colonoscopy on CRC incidence and mortality.
Population-based retrospective cohort study.
Ontario provincial health data information.
This study involved average-risk persons aged 50 to 74 years from 1996 to 2000 who were alive and free of CRC on January 1, 2001.
Colonoscopy between 1996 and 2000.
CRC incidence and mortality from 2001 to 2007.
The study cohort contained 1,089,998 persons, 7.9% of whom had undergone a colonoscopy between 1996 and 2000. Using primary care physician rate of discretionary colonoscopy as an instrumental variable, the receipt of colonoscopy was associated with a 0.60% (95% confidence interval [CI], 0.31%-0.78%) absolute reduction in the 7-year colorectal cancer incidence and a 0.17% (95% CI, 0.14%-0.21%) absolute reduction in the 5-year risk of death caused by CRC. This corresponds to a 48% relative decrease in CRC incidence (risk ratio [RR] 0.52; 95% CI, 0.34-0.76) and 81% decrease in mortality caused by CRC (RR 0.19, 95% CI, 0.07-0.47). In subgroup analyses, the reduction in the risk of death due to CRC was larger in women than men. The reduction in CRC incidence was larger for complete colonoscopies and for left-sided cancers.
Instrumental variable methods estimate only the marginal effect on the population studied.
Increased use of colonoscopy procedures is associated with a reduction in the incidence and mortality of CRC in the population studied.
The laboratory rat (Rattus norvegicus) is an indispensable tool in experimental medicine and drug development, having made inestimable contributions to human health. We report here the genome sequence of the Brown Norway (BN) rat strain. The sequence represents a high-quality 'draft' covering over 90% of the genome. The BN rat sequence is the third complete mammalian genome to be deciphered, and three-way comparisons with the human and mouse genomes resolve details of mammalian evolution. This first comprehensive analysis includes genes and proteins and their relation to human disease, repeated sequences, comparative genome-wide studies of mammalian orthologous chromosomal regions and rearrangement breakpoints, reconstruction of ancestral karyotypes and the events leading to existing species, rates of variation, and lineage-specific and lineage-independent evolutionary events such as expansion of gene families, orthology relations and protein evolution.