Phased Patagonian Ice Sheet response to Southern Hemisphere atmospheric and oceanic warming between 18 and 17 ka.

The onset of deglaciation in the Southern Hemisphere mid-latitudes has been attributed to the southward transmission of climate anomalies in response to slow-down of Atlantic meridional overturning circulation (AMOC) during Heinrich Stadial 1 (HS-1; 18-14.6 ka). However, inferences on the response of former ice sheets to sub-millennial palaeoclimate shifts are limited by a shortage of high-resolution terrestrial archives. Here we use a ~1000-year duration, annually-resolved lake sediment record to investigate the deglacial retreat dynamics of the Lago General Carrera-Buenos Aires ice lobe (46.5°S) of the former Patagonian Ice Sheet. We attribute the onset of glacier retreat at 18.0 ± 0.14 cal ka BP to abrupt southward migration of the Southern Westerly Winds that enhanced solar radiation receipt (and ablation) at the ice sheet surface. We infer that accelerated retreat from 17.77 ± 0.13 cal ka BP represents a lagged Southern Hemisphere response to gradual ocean-atmosphere warming associated with the centennial-scale transmission of Northern Hemisphere climate anomalies through the oceanic bipolar seesaw. By 17.38 ± 0.12 cal ka BP, the glacier margin had receded into a deepening proglacial lake, instigating sustained calving losses and more rapid ice recession.

The biological effects upon the cardiovascular system consequent to exposure to particulates of less than 500 nm in size.

CONTEXT: Ultrafine particulate matter contribution to cardiovascular disease is not known and not regulated. PM up to 500 nm are abundant in urban air and alveolar deposition is significant. OBJECTIVE: Effects beyond the alveolar barrier within the body or in vitro tissues exposed to particles <500 nm. DATABASES: MEDLINE; Ovid-MEDLINE PREM; Web of Science; PubMed (SciGlobe). 127 articles. Results in tables: "subject type exposed", "exposure type", "technique". CONCLUSION: Heart rate, vasoactivity, atherosclerotic advancement, oxidative stress, coagulability, inflammatory changes are affected. Production of reactive oxygen species is a useful target to limit outcomes associated with UFP exposure.

Maximal extent of translocation of single-walled carbon nanotubes from lung airways of the rat.

This study aimed to examine the extent of pulmonary translocation of single-walled carbon nanotubes (SWCNTs) from lung airways of rat. It utilised an ex vivo isolated perfused rat lung (IPRL) model that retains the intact lung architecture while eliminating the confounding issue of systemic pharmacokinetics. Doses (100 µg) of SWCNTs were instilled into the airways of the IPRL and the pulmonary translocation of SWCNTs quantified by inductively coupled plasma mass spectroscopy using CNT-associated nickel as the probe. SWCNT translocation from the airways across an intact pulmonary barrier into what would be the systemic circulation was no greater than 0.05% of the instilled dose over 90 min. Pharmacokinetic simulation incorporating a term for mucociliary clearance would predict over a 14 day an approximate cumulative pulmonary translocation from rat lung of no greater than 0.15% from a 100 µg deposited dose.

Feasibility of using biomarkers in blood serum as markers of effect following exposure of the lungs to particulate matter air pollution.

Particulate matter (PM) air pollution has significant cardiopulmonary health effects. Serum biomarkers may elucidate the disease mechanisms involved and provide a means for biomonitoring exposed populations, thereby enabling accurate policy decisions on air quality standards to be made. For this review, research investigating association of blood serum biomarkers and exposure to PM was identified, finding 26 different biomarkers that were significantly associated with exposure. Recent evidence links different effects to different components of PM. Future research on biomarkers of effect will need to address exposure by all PM size fractions.

Gene and protein responses of human lung tissue explants exposed to ambient particulate matter of different sizes.

CONTEXT: Exposure to ambient particulate air pollution is associated with increased cardiovascular and respiratory morbidity and mortality. It is necessary to understand causal pathways driving the observed health effects, particularly if they are differentially associated with particle size. OBJECTIVES: To investigate the effect of different size ranges of ambient particulate matter (PM) on gene and protein expression in an in vitro model. MATERIALS AND METHODS: Normal human tracheobronchial epithelium (NHTBE) three-dimensional cell constructs were exposed for 24 h to washed ambient PM of different sizes (size 1: 7-615 nm; size 2: 616 nm-2.39 µm; size 3: 2.4-10 µm) collected from a residential street. A human stress and toxicity PCR array was used to investigate gene expression and iTRAQ was used to perform quantitative proteomics. RESULTS: Eighteen different genes of the 84 on the PCR array were significantly dysregulated. Treatment with size 2 PM resulted in the greatest number of genes with altered expression, followed by size 1 and lastly size 3. ITRAQ identified 317 proteins, revealing 20 that were differentially expressed. Enrichment for gene ontology classification revealed potential changes to various pathways. DISCUSSION AND CONCLUSIONS: Different size fractions of ambient PM are associated with dysregulatory effects on the cellular proteome and on stress and toxicity genes of NHTBE cells. This approach not only provides an investigative tool to identify possible causal pathways but also permits the relationship between particle size and responses to be explored.

Association between protozoa in sputum and asthma: a case-control study.

BACKGROUND: Atypical infectious agents have been proposed as potential contributors to asthma. A novel set of morphological and staining criteria permit the identification of flagellated protozoa in sputum. This case-control study was designed to use this novel method and to assess: (1) are protozoa more common in asthmatics than in non-asthmatics; (2) is the presence of protozoa associated with the use of steroid inhalers; and (3) is the presence of protozoa associated with living in damp housing? METHODS: Induced sputum samples were collected from asthma patients and local non-atopic, non-smoking controls. Questionnaires assessed asthma severity and housing conditions. Sputum was examined for flagellated protozoa using a previously described staining technique. RESULTS: 96 participants were recruited for this study; 54 asthma patients and 42 controls, age range 21-62 years, 70% female participants. Limiting results to those who were clearly positive or negative for flagellated protozoa, 66.7% (20/30) of asthmatics and 30.8% (4/13) of controls had protozoa (p = 0.046). Among the asthma patients, prevalence of protozoa was not significantly different between those who had (10/18), and those who had not (10/12), used steroid inhaler in the preceding two weeks (p = 0.11). Similarly, the prevalence of protozoa was not significantly different between those who did (6/11) and those who did not (18/32), live in damp homes (p = 0.92). CONCLUSIONS: This case-control study demonstrates an association between flagellated protozoa in sputum and asthma. It is now necessary to confirm and characterise the protozoa using genetic techniques based on 18S ribosomal RNA. Once tis is established it would be worthwhile to determine if asthma symptoms improve when treated by anti-protozoal agents.

Outdoor and indoor respirable air particulate concentrations in differing urban traffic microenvironments.

To study the adverse health effects associated with ambient respirable particulates it is necessary to assess population exposure. However, measurements are usually carried out by fixed-site air monitoring units and do not take into consideration the range of urban microenvironments. In particular, vehicular emissions are a major source of particulates in cities and it is therefore necessary to consider traffic density when investigating the adverse health effects of air particulates. This study assessed both PM(5) and total particle number (TPN) in areas of high and low traffic flow within the city of Cardiff, UK. Daytime measurements were made outdoors throughout the period January 2004-June 2005. Simultaneous indoor measurements were made in 73 participating households in areas of high traffic flow (exposed) and 50 households in areas of low traffic flow (controls). The median outdoor PM(5) concentration in the exposed area (16.7 microg cm(-3)) was 45% significantly higher than that in the unexposed area (11.5 microg cm(-3)) and the median TPN in the exposed area (18,130 particles cm(-3)) was almost double that in the unexposed area (9951 particles cm(-3)). The median indoor concentration of PM(5) in the exposed area (13.2 microg cm(-3)) was also 40% significantly higher than that in the unexposed area (9.4 microg cm(-3)), but there was almost no difference in indoor median TPN between the two areas: 8999 particles cm(-3) and 8549 particles cm(-3), respectively. The observed differences in respirable particles between areas of high and low traffic flow underline the importance of obtaining exposure measurements in microenvironments.

Real-time measurement of short-term peaks in environmental CO concentrations in the homes of the elderly in South Wales.

In order to determine whether short-term World Health Organization (WHO) guideline limits for carbon monoxide (CO) are exceeded in the home environment, a number of sensors were constructed capable of real-time measurement. These were deployed for a period of 7 days to continuously monitor CO concentrations in 44 non-smoking households using either gas, coal, electricity, liquid propane gas, or oil for heating fuel in South Wales. The mean environmental concentrations over the period monitored were less than 1 p.p.m and WHO short-term limits were not exceeded in any household. In another 20 homes containing a smoker the mean concentrations measured over a period of 2 days ranged from 0.1 to 21 p.p.m and WHO short-term limits were exceeded in one household.

Chronic arsenic exposure and urinary 8-hydroxy-2'-deoxyguanosine in an arsenic-affected area in Inner Mongolia, China.

OBJECTIVE: Recent studies have shown that generation of reactive oxidants during arsenic metabolism can play an important role in arsenic-induced injury. The purpose of this study was to examine the relationship between arsenic in drinking water and oxidative stress in humans by measuring 8-Hydroxy-2'-deoxyguanosine (8-OHdG). METHODS: We performed a cross-sectional study in an arsenic-affected village in Hetao Plain, Inner Mongolia, China. A total of 134 of the 143 inhabitants (93.7%) of the village participated in the study. The levels of 8-OHdG, arsenic and its metabolites were measured in urine collected from the participants. Regression analyses were performed to investigate the relationship between arsenic species and 8-OHdG levels in urine. RESULTS: In the polluted village, monomethylarsenic was significantly higher in subjects with arsenic dermatosis than those without dermatosis despite no difference in mean levels of arsenic in well water between both types of subject. For subjects with arsenic dermatosis, arsenic species and metabolites in urine are significantly associated with 8-OHdG, while there was no statistically significant relationship for subjects without arsenic dermatosis. For all residents of the polluted village, the levels of dimethylarsenic and 8-OHdG were significantly higher for those who had been exposed to well water for more than 12 years. CONCLUSIONS: These results provide evidence of a link between exposure to arsenic from drinking water and oxidative stress, which may play an important role in arsenic-involved injuries.