Comparative foliar metabolomics of a tropical and a temperate forest community.

Plant enemies that attack chemically similar host species are thought to mediate competitive exclusion of chemically similar plants and select for chemical divergence among closely related species. This hypothesis predicts that plant defenses should diverge rapidly, minimizing phylogenetic signal. To evaluate this prediction, we quantified metabolomic similarity for 203 tree species that represent >89% of all individuals in large forest plots in Maryland and Panama. We constructed molecular networks based on mass spectrometry of all 203 species, quantified metabolomic similarity for all pairwise combinations of species, and used phylogenetically independent contrasts to evaluate how pairwise metabolomic similarity varies phylogenetically. Leaf metabolomes exhibited clear phylogenetic signal for the temperate plot, which is inconsistent with the prediction. In contrast, leaf metabolomes lacked phylogenetic signal for the tropical plot, with particularly low metabolomic similarity among congeners. In addition, community-wide variation in metabolomes was much greater for the tropical community, with single tropical genera supporting greater metabolomic variation than the entire temperate community. Our results are consistent with the hypothesis that stronger plant-enemy interactions lead to more rapid divergence and greater metabolomic variation in tropical than temperate plants. Additional community-level foliar metabolomes will be required from tropical and temperate forests to evaluate this hypothesis.

Surveillance for early silicosis in high altitude miners using pulse oximetry.

Two cross-sectional studies in a high altitude region of Perú evaluated the role of pulse oximetry for detection of silicosis in high-altitude miners. In study one, exercise pulse oximetry and chest radiographs were used to evaluate 343 silica-exposed miners and 141 unexposed subjects for evidence of silicosis. Study 2 investigated the association between exercise oxygen saturation and silicosis in 32 non-silicotic and 65 silicotic miners. In study one, age (Odds Ratio [OR] 1.10, 95% Cofidence Interval (CI) 1.07-1.12) and resting oxygen saturation (OR 0.95, 95%CI 0.90-0.99) were associated with silicosis. In study two, years of mining employment (OR 1.14, 95%CI 1.05-1.23) and exercise oxygen saturation at 30% maximum heart rate (OR 0.86, 95%CI 0.75-0.99) were associated with silicosis. Hypoxemia at rest and with exercise is associated with silicosis in high altitude miners. Pulse oximetry should be further investigated as a screening tool for silicosis at high altitudes.

Karyotype diversification and evolution in diploid and polyploid South American Hypochaeris (Asteraceae) inferred from rDNA localization and genetic fingerprint data.

BACKGROUND AND AIMS: Changes in chromosome structure and number play an important role in plant evolution. A system well-suited to studying different modes of chromosome evolution is the genus Hypochaeris (Asteraceae) with its centre of species' diversity in South America. All South American species uniformly have a chromosome base number of x = 4 combined with variation in rDNA number and distribution, and a high frequency of polyploidy. The aim of this paper is to assess directions and mechanisms of karyotype evolution in South American species by interpreting both newly obtained and previous data concerning rDNA localization in a phylogenetic context. METHODS: Eleven Hypochaeris species from 18 populations were studied using fluorescence in situ hybridization (FISH) with 35S and 5S rDNA probes. A phylogenetic framework was established from neighbour-net analysis of amplified fragment length polymorphism (AFLP) fingerprint data. KEY RESULTS: A single 5S rDNA locus is invariably found on the short arm of chromosome 2. Using 35S rDNA loci, based on number (one or two) and localization (interstitial on the long arm of chromosome 2, but sometimes lacking, and terminal or interstitial on the short arm of chromosome 3, only very rarely lacking), seven karyotype groups can be distinguished; five of these include polyploids. Karyotype groups with more than one species do not form monophyletic groups. CONCLUSIONS: Early evolution of Hypochaeris in South America was characterized by considerable karyotype differentiation resulting from independent derivations from an ancestral karyotype. There was marked diversification with respect to the position and evolution of the 35S rDNA locus on chromosome 3, probably involving inversions and/or transpositions, and on chromosome 2 (rarely 3) concerning inactivation and loss. Among these different karyotype assemblages, the apargioides group and its derivatives constitute by far the majority of species.

Effect of diuretic therapy on exercise capacity in patients with chronic angina and preserved left ventricular function.

AIM: This study was designed to determine whether therapy with a diuretic has antianginal effects in patients with stable angina who are already treated with a traditional antianginal regimen. METHODS AND RESULTS: Forty patients with chronic stable angina and normal left ventricular function were randomized in a double-blind, placebo-controlled study. Background antianginal therapy included beta blockers (n = 27), calcium channel antagonists (n = 18), and long-acting nitrates (n = 24). Of the patients 30% had diabetes and 75% had a history of hypertension. Patients were treated with a diuretic (hydrochlorothiazide 25 mg plus amiloride 5 mg) or placebo for 21 days. All patients underwent a treadmill exercise test before randomization and at day 21. The primary end point was the change in treadmill walking time until moderate angina. Diuretic therapy was associated with an increase in treadmill walking time of 63 +/- 17 seconds versus 19 +/- 9 seconds in the placebo group (P = 0.026) and reduced ST-segment depression (0.6 +/- 0.2 mm versus 0.1 +/- 0.2 mm (P = 0.03). There was a 25% increase in walking time in 8 patients (40%) treated with diuretic versus 1 patient (5%) in the placebo group (P = 0.02). The increases did not depend on changes in blood pressure or heart rate. CONCLUSION: Therapy with hydrochlorothiazide plus amiloride has potent antianginal effects in patients with stable angina and preserved left ventricular function under treatment with standard antianginal therapy. Because most of the study patients had a history of hypertension the extrapolation of these findings to patients who did not have hypertension requires further investigation.

Técnicas de imágenes de tórax para enfermedades / Chest imaging techniques for asbestos-related diseases

El asbesto es una sustancia que puede provocar distintas alteraciones en los exámenes de imagen pleuro-pulmonar: asbestosis, engrosamientos pleurales, derrame pleural, tumores pulmonares y mesotelioma. En este artículo se revisan los principales métodos diagnósticos de estas enfermedades: Radiografía de Tórax, Tomografía Computarizada de Tórax (tradicional y de alta resolución), y otros. Se discuten las ventajas y desventajas de cada uno de ellos, así como su indicación en la vigilancia en salud ocupacional. Por último, se menciona y explica brevemente la clasificación de la Organización Internacional del Trabajo (OIT) para las radiografías de tórax.