Air Quality in Africa: Public Health Implications.

This review highlights the importance of air quality in the African urban development process. We address connections between air pollution and (a) rapid urbanization, (b) social problems, (c) health impacts, (d) climate change, (e) policies, and (f) new innovations. We acknowledge that air pollution levels in Africa can be extremely high and a serious health threat. The toxic content of the pollution could relate to region-specific sources such as low standards for vehicles and fuels, cooking with solid fuels, and burning household waste. We implore the pursuit of interdisciplinary research to create new approaches with relevant stakeholders. Moreover, successful air pollution research must regard conflicts, tensions, and synergies inherent to development processes in African municipalities, regions, and countries. This includes global relationships regarding climate change, trade, urban planning, and transportation. Incorporating aspects of local political situations (e.g., democracy) can also enhance greater political accountability and awareness about air pollution.

Intercomparison of in-situ aircraft and satellite aerosol measurements in the stratosphere.

Aerosol composition and optical scattering from particles in the lowermost stratosphere (LMS) have been studied by comparing in-situ aerosol samples from the IAGOS-CARIBIC passenger aircraft with vertical profiles of aerosol backscattering obtained from the CALIOP lidar aboard the CALIPSO satellite. Concentrations of the dominating fractions of the stratospheric aerosol, being sulphur and carbon, have been obtained from post-flight analysis of IAGOS-CARIBIC aerosol samples. This information together with literature data on black carbon concentrations were used to calculate the aerosol backscattering which subsequently is compared with measurements by CALIOP. Vertical optical profiles were taken in an altitude range of several kilometres from and above the northern hemispheric extratropical tropopause for the years 2006-2014. We find that the two vastly different measurement platforms yield different aerosol backscattering, especially close to the tropopause where the influence from tropospheric aerosol is strong. The best agreement is found when the LMS is affected by volcanism, i.e., at elevated aerosol loadings. At background conditions, best agreement is obtained some distance (>2 km) above the tropopause in winter and spring, i.e., at likewise elevated aerosol loadings from subsiding aerosol-rich stratospheric air. This is to our knowledge the first time the CALIPSO lidar measurements have been compared to in-situ long-term aerosol measurements.

An extraterrestrial trigger for the mid-Ordovician ice age: Dust from the breakup of the L-chondrite parent body.

The breakup of the L-chondrite parent body in the asteroid belt 466 million years (Ma) ago still delivers almost a third of all meteorites falling on Earth. Our new extraterrestrial chromite and 3He data for Ordovician sediments show that the breakup took place just at the onset of a major, eustatic sea level fall previously attributed to an Ordovician ice age. Shortly after the breakup, the flux to Earth of the most fine-grained, extraterrestrial material increased by three to four orders of magnitude. In the present stratosphere, extraterrestrial dust represents 1% of all the dust and has no climatic significance. Extraordinary amounts of dust in the entire inner solar system during >2 Ma following the L-chondrite breakup cooled Earth and triggered Ordovician icehouse conditions, sea level fall, and major faunal turnovers related to the Great Ordovician Biodiversification Event.

Significant radiative impact of volcanic aerosol in the lowermost stratosphere.

Despite their potential to slow global warming, until recently, the radiative forcing associated with volcanic aerosols in the lowermost stratosphere (LMS) had not been considered. Here we study volcanic aerosol changes in the stratosphere using lidar measurements from the NASA CALIPSO satellite and aircraft measurements from the IAGOS-CARIBIC observatory. Between 2008 and 2012 volcanism frequently affected the Northern Hemisphere stratosphere aerosol loadings, whereas the Southern Hemisphere generally had loadings close to background conditions. We show that half of the global stratospheric aerosol optical depth following the Kasatochi, Sarychev and Nabro eruptions is attributable to LMS aerosol. On average, 30% of the global stratospheric aerosol optical depth originated in the LMS during the period 2008-2011. On the basis of the two independent, high-resolution measurement methods, we show that the LMS makes an important contribution to the overall volcanic forcing.

Imaging of adrenal incidentalomas with PET using (11)C-metomidate and (18)F-FDG.

UNLABELLED: Our aim was to evaluate the use of PET with (11)C-metomidate and (18)F-FDG for the diagnosis of adrenal incidentalomas. METHODS: Twenty-one patients underwent hormonal screening before dynamic imaging of the upper abdomen with (11)C-metomidate, and for 19 of these 21 patients, static (18)F-FDG imaging followed. Uptake of (11)C-metomidate and (18)F-FDG in incidentalomas was quantified and correlated with the hormonal work-up and the mass size on CT (median, 2.5 cm; range, 2-10 cm). RESULTS: The final diagnoses were hormonally active adenoma (n = 7), nonsecretory adenoma (n = 5), adrenocortical carcinoma (n = 1), pheochromocytoma (n = 2), benign noncortical tumor (n = 2), normal adrenal (n = 1), and malignant noncortical tumor (n = 3). Diagnosis was established at surgery (n = 9), percutaneous biopsy (n = 4), or follow-up (n = 8). The highest uptake of (11)C-metomidate, expressed as standardized uptake value (SUV), was found in adrenocortical carcinoma (SUV = 28.0), followed by active adenomas (median SUV = 12.7), nonsecretory adenomas (median SUV = 12.2), and noncortical tumors (median SUV = 5.7). Patients with adenomas had significantly higher tumor-to-normal-adrenal (11)C-metomidate SUV ratios than did patients with noncortical tumors. (18)F-FDG detected 2 of 3 noncortical malignancies but failed to detect adrenal metastases from renal cell carcinoma. All inactive and most active adenomas were difficult to detect with (18)F-FDG against background activity, whereas both pheochromocytomas and adrenocortical carcinoma showed slightly increased uptake of (18)F-FDG. There was no correlation between uptake of (11)C-metomidate or (18)F-FDG and mass size. CONCLUSION: (11)C-Metomidate is a promising PET tracer to identify incidentalomas of adrenocortical origin. (18)F-FDG should be reserved for patients with a moderate to high likelihood of neoplastic disease.

Exercise release of cardiac natriuretic peptides is markedly enhanced when patients with coronary artery disease are treated medically by beta-blockers.

OBJECTIVES: This study sought to identify determinants of the exercise rise in plasma levels of cardiac natriuretic peptides (NPs) in patients with coronary artery disease (CAD). BACKGROUND: During stress, there is a variable rise in the plasma level of NPs, but this rise frequently reaches levels that are known to lower the cardiac load and that thus might be beneficial to CAD patients. METHODS: Plasma venous concentrations of atrial natriuretic peptide (ANP) and brain natriuretic peptide (BNP) were determined at rest and peak exercise in 104 patients with chronic CAD who were referred to exercise thallium-201 ((201)Tl) single-photon emission computed tomography (SPECT) and radionuclide angiography. RESULTS: The extent of scarred myocardium by (201)Tl-SPECT and patient age were the best independent predictors of NP concentrations at rest, but also of increases in NP concentration during exercise (all p < 0.001). Moreover, beta-blocking treatment was an additional and strong independent predictor of the increase in NP concentrations at exercise (p < 0.001 for ANP; p = 0.001 for BNP). On average, exercise increases in NP concentrations were more than twice as high in patients with (n = 55) than in those without (n = 49) beta-blocker treatment (ANP: +49 +/- 63 vs. +22 +/- 25 ng/l, p = 0.01; BNP: +24 +/- 5 vs. +11 +/- 15 ng/l, p = 0.04), whereas NP concentrations at rest were equivalent in the two groups (ANP: 34 +/- 34 vs. 30 +/- 33 ng/l, p = NS; BNP: 85 +/- 152 vs. 57 +/- 101 ng/l, p = NS). CONCLUSIONS: Patients with chronic CAD exhibit much higher exercise releases of ANP and BNP when they are treated with beta-blockers. This enhanced secretion of potent vasodilating and natriuretic agents constitutes an original therapeutic mechanism for further protecting diseased hearts against stress.

Early impairment of coronary flow reserve is not associated with Chlamydia pneumoniae antibodies.

BACKGROUND: Chlamydia pneumoniae infection has been associated with atherosclerosis by sero-epidemiological, histopathological and interventional studies, and animal experiments. We hypothesized that if chlamydial infection is causative of atherosclerosis, the occurrence of antibodies against C. pneumoniae should be associated with coronary vasomotor dysfunction - an early sign of atherosclerosis. AIM: To study the association between C. pneumoniae infection and coronary vasomotor function in young men without signs of ischemic heart disease. METHODS: Serum IgG and IgA antibody concentrations against C. pneumoniae were determined in 125 clinically healthy subjects undergoing positron emission tomography (PET) studies. Myocardial blood flow was measured at rest and during pharmacologically induced hyperemia using [15O]H2O Coronary flow reserve was calculated as the ratio of hyperemic blood flow to resting blood flow. RESULTS: No association was found between serum C. pneumoniae antibody concentrations and myocardial blood flow parameters. In contrast, more conventional risk factors for coronary artery disease, such as total cholesterol and apolipoprotein B, were inversely associated with hyperemic flow and flow reserve. CONCLUSIONS: We found no association between C. pneumoniae antibodies and coronary vasomotor function in subjects without ischemic heart disease. Thus, these results do not support the role of C. pneumoniae infection as an early phase risk factor for coronary artery disease.