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Objectives: COPD with emphysema causes marked neurohumoral activation. Angiotensin II receptors are highly expressed within the lung and interfere with mechanisms involved in the progression of emphysema. This study examined the effects of an angiotensin II receptor blocker (ARB) on pulmonary and systemic manifestations of emphysema in a mouse model., Methods: Female NMRI mice received five intratracheal instillations of porcine pancreatic elastase (emphysema; n = 11) or phosphate-buffered saline (PBS; n = 4). Emphysema severity was quantified histologically by mean linear intercept, exercise tolerance by treadmill running distance, and lung biomechanics by compliance. Following emphysema induction, 6 mice were treated with the ARB irbesartan for 8 weeks, while 5 mice receiving standard food served as controls., Results: Following emphysema induction, mean linear intercept was higher in elastase-treated than in PBS-treated lungs (103.0 ± 6.2 μm vs. 35.0 ± 0.6 μm; p = 0.043) while running distance was shorter in emphysema mice (418.6 ± 83.5 m vs. 906.6 ± 244.6 m, p = 0.028). Irbesartan-treated emphysema mice showed a lower mean linear intercept (90.8 ± 3.8 μm vs. 121.5 ± 8.1 μm; p = 0.005), improved compliance (163.6 ± 55.9 μl/cmH(2)O vs. 354.4 ± 72.5 μl/cmH(2)O; p = 0.063) and greater running distance (p ANOVA = 0.015) compared to emphysema mice receiving standard food., Conclusions: The ARB irbesartan elicits encouraging beneficial effects on emphysema severity, lung biomechanics and exercise capacity in an emphysema mouse model. These findings might help to understand the corresponding positive effects of angiotensin II receptor blockade noticed in patients with COPD., (Copyright © 2010 Elsevier Ltd. All rights reserved.)

The origin of life on Earth may be divided into two stages separated by the first appearance of replicable molecules, most probably of RNA. The first stage depended exclusively on chemistry. The second stage likewise involved chemistry, but with the additional participation of selection, a necessary concomitant of inevitable replication accidents. Consideration of these two processes suggests that the origin of life may have been close to obligatory under the physical-chemical conditions that prevailed at the site of its birth. Thus, an extrasolar planet in which those conditions were replicated appears as a probable site for the appearance of extra-terrestrial life.

Life is the product of chemistry, which obeys deterministic laws, and of natural selection, which operates on variants offered to it by chance, but may, in a number of cases, have been provided with a sufficiently extensive array of variants to be optimizing. Thus, the origin and evolution of life have been largely shaped by the contingency of environmental conditions. The possibility remaining open for consideration is that certain critical conditions are sufficiently reproducible for life to arise and even to evolve into conscious, intelligent beings elsewhere in the universe.

In the course of an investigation aimed at characterizing hepatic glucose 6-phosphatase, the unrelated acid phosphatase of rat liver was serendipitously observed to be latent and particle-bound in freshly prepared homogenates. Experiments designed to elucidate this intriguing finding led, 50 years ago, to the discovery of lysosomes. This could not have happened if strict adherence to a previously set programme had been mandatory.

This paper describes some experiments the author would have liked to carry out if he had started earlier in the origin-of-life field. The proposal is preceded by a hypothetical outline of the main events in the origin of life. According to this outline, the emergence of life amounts to the transition between two kinds of chemistry: 1) cosmic chemistry, which is beginning to be understood and most likely provided the building blocks with which life was first constructed; and 2) biochemistry, the well-known set of enzyme-catalyzed metabolic reactions that support all living organisms today and must have supported the universal common ancestor, or LUCA, from which all known forms of life are derived. The pathway leading from one to the other of those two chemistries may be divided into three stages, defined as the pre-RNA, RNA, and protein-DNA stages. A brief summary of the events that may have occurred in these three stages and of the possible underlying mechanisms is given. It is emphasized that these events were chemical in nature and, especially, that they must have prefigured present-day biochemical processes. Protometabolism and metabolism, it is argued, must have been congruent. With congruence as the underlying working hypothesis, three problems open to experimental investigation are considered: 1) the involvement of peptides and other multimers as catalysts of early biogenic chemistry; 2) the participation of thioesters in primitive energy transactions; and 3) the influence of amino acids on the molecular selection of RNA molecules.

The subcellular distribution of the biosynthetic intermediates of catalase was studied in the livers of rats receiving a mixture of [(3)H]leucine and [(14)C]delta-aminolevulinic acid by intraportal injection. Postnuclear supernates were fractionated by a one-step gradient centrifugation technique that separates the main subcellular organelles, partly on the basis of size, and partly on the basis of density. Labeled catalase and its biosynthetic intermediates were separated from the gradient fractions by immunoprecipitation, and the distributions of radioactivity were compared with those of marker enzymes. The results show that catalase protein is synthesized outside the peroxisomes, but rapidly appears in these particles, mostly still in the form of the first hemeless biosynthetic intermediate. Addition of heme and completion of the catalase molecule take place within the peroxisomes. During the first 15 min after [(3)H]leucine administration, more than half of the newly formed first intermediate was recovered in the supernatant fraction, where it was found to exist as an aposubunit of about 60,000 molecular weight.

Cytochemical methods for acid phosphatase and catalase were applied to atheromatous aortas from cholesterol-fed rabbits. Whole tissue, partially digested aortic slices and isolated cells were used for the study. Present in the atheromatous lesions were smooth muscle cells in all stages of foamy transformation, from virtually normal appearing smooth muscle cells to severely altered cells with pronounced lipid accumulation. The results with the acid phosphatase method show that lysosomes increase both in size and in number as the smooth muscle cells become foam cells. In normal appearing smooth muscle cells, acid phosphatase reaction product was found in stacked cisternae of the Golgi apparatus and in small vesicles located in the Golgi region and distributed throughout the cytoplasm. In foam cells, reaction product was found in membrane-limited vacuoles of varying size which typically contained membranous debris or myelin-like figures together with massive lipid deposits. No reaction was seen in "free" cytoplasmic lipid droplets lacking a surrounding membrane. These results confirm and extend previous biochemical findings indicating that, in the cholesterol-fed rabbit, the change from normal smooth muscle cell to foam cell is accompanied by marked physical and chemical changes of the lysosomes, including their progressive overloading with cholesteryl ester. Small diaminobenzidine-positive particles were present in normal smooth muscle cells and in those at all stages of foamy transformation. These particles were more frequent in foam cells, in agreement with the marked increase in catalase activity detected biochemically in these cells.