SERUM LIPIDS IN NORMAL AND ABNORMAL SUBJECTS—Observations on Controlled Experiments

The relationship of diet to serum lipids and to atherosclerosis is a controversial subject. The data presented indicate that diets containing very large amounts of vegetable fat are consistently associated with a sharp fall in serum cholesterol and phospholipid, whereas administration of equal amounts of fat of animal origin is associated with a rise of the serum lipids to levels noted on an average mixed diet.In critical evaluation of elderly hospitalized diabetic patients with advanced atherosclerosis it was observed that there was close mathematical correlation between serum content of cholesterol, “lipoproteins,” and phospholipids. There was no obvious correlation between the degree or kind of atherosclerosis and any one of the lipid entities followed. Coronary occlusion occurred in a patient with one of the lowest levels of cholesterol and of lipoprotein.     

Amazon aquatic biodiversity imperiled by oil spills

Oil exploitation poses a significant threat to freshwater biodiversity, and future plans to develop petroleum leases in the Amazon Basin should be seem with caution. A series of oil spills have significantly affected biodiversity and human activities in some Amazonian basins, indicating that disturbances by petroleum activities will increase in the region, particularly in upper basins and river headwaters. Measures are needed to reduce the risk of spills and to minimize their impacts. More fundamentally, changes in decision making are needed that give proper weight to these impacts.     

Characteristics of the Psidium cattleianum invasion of secondary rainforests

Strawberry guava (Psidium cattleianum) is a shade‐tolerant shrub or small tree invader in tropical and subtropical regions and is considered among the world's top 100 worst invasive species. Studies from affected regions report deleterious effects of strawberry guava invasion on native vegetation. Here we examine the life history demographics and environmental determinants of strawberry guava invasions to inform effective weed management in affected rainforest regions. We surveyed the vegetation of 8 mature rainforest and 33 successional sites at various stages of regeneration in the Australian Wet Tropics and found that strawberry guava invasion was largely restricted to successional forests. Strawberry guava exhibited high stem and seedling densities, represented approximately 8% of all individual stems recorded and 20% of all seedlings recorded. The species also had the highest basal area among all the non‐native woody species measured. We compared environmental and community level effects between strawberry guava‐invaded and non‐invaded sites, and modelled how the species basal area and recruitment patterns respond to these effects. Invaded sites differed from non‐invaded sites in several environmental features such as aspect, distance from intact forest blocks, as well as supported higher grass and herb stem densities. Our analysis showed that invasion is currently ongoing in secondary forests, and also that strawberry guava is able to establish and persist under closed canopies. If left unchecked, strawberry guava invasion will have deleterious consequences for native regenerating forest in the Australian Wet Tropics.     

Motor Neuron Disease in the Rocky Mountain Region

We saw 166 patients with motor neuron disease over a ten-year period, 116 with amyotrophic lateral sclerosis–111 sporadic and 5 familial–and 50 with progressive muscular atrophy. The age at onset varied widely, with the youngest mean onset occurring in the familial group. The most common presenting symptoms were leg or arm weakness and difficulty speaking or swallowing; fewer patients reported cramping, fasciculation, or fatigue. Mean survival time was less in familial cases, women, older patients, and in those with difficulty speaking and swallowing. A total of 50% of all patients were alive after four years; 13% were alive after ten years. Previous reports on the natural history of motor neuron disease may be overly pessimistic in suggesting that survival time rarely exceeds two years.     

Hydroxycarbamide Decreases Sickle Reticulocyte Adhesion to Resting Endothelium by Inhibiting Endothelial Lutheran/Basal Cell Adhesion Molecule (Lu/BCAM) through Phosphodiesterase 4A Activation

Vaso-occlusive crises are the main acute complication in sickle cell disease. They are initiated by abnormal adhesion of circulating blood cells to vascular endothelium of the microcirculation. Several interactions involving an intricate network of adhesion molecules have been described between sickle red blood cells and the endothelial vascular wall. We have shown previously that young sickle reticulocytes adhere to resting endothelial cells through the interaction of α₄β₁ integrin with endothelial Lutheran/basal cell adhesion molecule (Lu/BCAM). In the present work, we investigated the functional impact of endothelial exposure to hydroxycarbamide (HC) on this interaction using transformed human bone marrow endothelial cells and primary human pulmonary microvascular endothelial cells. Adhesion of sickle reticulocytes to HC-treated endothelial cells was decreased despite the HC-derived increase of Lu/BCAM expression. This was associated with decreased phosphorylation of Lu/BCAM and up-regulation of the cAMP-specific phosphodiesterase 4A expression. Our study reveals a novel mechanism for HC in endothelial cells where it could modulate the function of membrane proteins through the regulation of phosphodiesterase expression and cAMP-dependent signaling pathways.     

Unanticipated Effects of Stand Dynamism on Amazonian Tree Diversity

We assessed a general hypothesis of tropical tree diversity that predicts that species richness will be positively correlated with stand dynamism. Our analysis was based one of the largest and longest-running datasets on Amazonian trees (≥10 cm diameter at breast height), with data collected over a 23-yr period within 66 1 ha plots spanning a large (1000 km²) landscape. Within these plots, maximum tree-species richness (329 species/ha) and Fisher's α values (227.5) were among the highest ever recorded. Contrary to the diversity-dynamism concept, tree species richness in our landscape was significantly and negatively associated with stand dynamism (measured as the mean rate of annual tree turnover). Because of this unexpected finding, we critically re-evaluated the relationship between stand dynamism and tree diversity across the Amazon basin and the tropics as a whole. With the inclusion of additional data we found that the relationship between stand dynamism and tree diversity becomes non-significant at larger spatial scales.