Experimental investigations in prolonged myocardial ischaemia. Note I. Biology of the myocardial fiber after transient myocardial fiber after transient myocardial ischaemia

The first ten days' evolution of post-ischaemic lesions of the premonitory or angina pectoris syndrome type was experimentally studied by the challenge of a short-term (10 and 15 min) ischaemia, of an adaptation to ischaemia and an adaptation followed by prolonged ischaemia (20 and 35 min). Worthy of note was the persistence of reversible lesions after short-term ischaemia and adaptation, and the progressive evolution towards cytolysis and cicatrization of some pancicellular foci after adaptation followed by prolonged ischaemia. The role of mitochondrial lesions, of lysosomal hydrolases, the inefficiency of renewed circulation, as well as problems of diagnosis are discussed.     

A Simple Survival Model for Combined Action of Two Damaging Agents

The aim of this study was mathematical formalization of the development of two damage processes in response to the combined action of two different damaging agents. The model allows to obtain the parametric family of distributions for the life-span when the organism's death is due to joint effect of two damage processes. Differing by their probabilistic meaning the notions of a priori (M (t)) and a posteriori (M(y)) conditional mean contributions of each damage process to the final effect of combined injury are introduced. The formulas permitting to compute the M and M values on the basis of survival data parametric analysis are given.     

The effect of sulfated polysaccharides on the free intracellular calcium ion concentration of lymphocytes

Recent studies have demonstrated that murine lymphocytes express specific cell-surface receptors for a range of sulfated polysaccharides. In order to determine whether polysaccharide binding induces transmembrane signaling, the effects of sulfated polysaccharides on the free intracellular calcium ion concentration [( Ca2+]i) of mouse thymocytes and spleen cells were determined. Cells were loaded with Indo-I, a fluorescent indicator of calcium ion concentration. The validity and limitations in the use of this indicator in the determination of [Ca2+]i are documented. Dextran sulfate (Mn = 500,000), iota-carrageenan, lambda-carrageenan and kappa-carrageenan all cause relatively large changes in the [Ca2+]i of thymocytes (change in [Ca2+]i greater than 50 nM). Of these, dextran sulfate (Mn = 500,000) always had the greatest effect on [Ca2+]i. Smaller responses were obtained with heparin and dextran sulfate (Mn = 5000), while no response was obtained with chondroitin 4-sulfate, chondroitin 6-sulfate, pentosan sulfate or fucoidin. This response pattern (with the exception of fucoidin and pentosan sulfate) corresponds with the expression of thymocyte receptors for these polysaccharides. The increase in [Ca2+]i caused by the sulfated polysaccharides requires extracellular Ca2+ ions however, it is unlikely that voltage-dependent ion channels are involved in these responses. In contrast to thymocytes, although spleen cells express receptors for sulfated polysaccharides, they were unresponsive to all of the sulfated polysaccharides tested, suggesting a basic difference between thymocytes and peripheral T and B lymphocytes in their response to the binding of sulfated polysaccharides.     

Relationship between cell density and prolidase activity in human skin fibroblasts: effects of ascorbate and fructose

To evaluate the influence of cell density on the activity of fibroblast prolidase (EC 3.4.13.9), we determined this activity in sparse and dense cultures. We also investigated, the effects of different concentrations of β-d(?) fructose and l(+) ascorbate, which both increased cell density at confluency. For a fructose concentration of 25 mM, we observed that in the absence of glucose, intracellular total proteins increased 1.5-fold and prolidase specific activity, 1.8-fold. For ascorbate, a broad optimum concentration was found (range 0.01 – 0.50 mM). Addition to cultures of 0.1 mM ascorbate increased total proteins 1.4-fold, and doubled prolidase activity. This investigation was prompted by our previous results [J. Metab. Dis. 1983, 6, 27–31], confirmed here, and suggesting that increased prolidase activity at confluency was due to a rise in cell density.     

Developmental Patterns of Catechol-O-Methyltransferase in Genetically Different Rat Strains: Enzymatic and Immunochemical Studies

Abstract: Catechol- O -methyltransferase (COMT) activity in the liver and kidneys of adult Fischer-344 (F-344) rats is only half of that in the same organs of Wistar-Furth (W-F) rats. The trait of low COMT activity in these animals is inherited in an autosomal recessive fashion. A comprehensive study of patterns of change in COMT activity during growth and development was performed to determine whether "temporal gene" effects might play a role in the inherited differences in enzyme activity present in adult animals. The COMT activity expressed per mg protein in liver and kidneys of newborn F-344 rats is only 50–60% of that in the same organs of W-F animals. The liver and the kidneys of newborn rats of both strains have COMT activity an order of magnitude higher than those in brain, heart, or blood. In addition, in both strains there are much larger increases in liver and kidney COMT activities during growth and development (5–10 fold) than in blood, brain, or heart (one- to twofold). Immunotitration with antibodies against rat COMT demonstrates that differences in immunoreactive COMT parallel differences in COMT activity, both between strains and within strains during growth and development. However, when the temporal patterns of change in enzyme activities in the liver and the kidneys of the two strains of rat are compared at multiple times during growth and development, no differences in the patterns are present. These results make it unlikely that temporal gene effects can explain the inherited differences in COMT activity in liver and kidneys of F-344 and W-F rats.     

Sex ratios under asymmetrical local mate competition in the parasitoid wasp Nasonia vitripennis

Sex ratio theory has proved remarkably useful in testing theadaptive nature of animal behavior. A particularly productivearea in this respect is Hamilton's theory of local mate competition(LMC), which has been extended in numerous directions to includegreater biological realism, allowing more detailed tests inspecific organisms. We have presented one such extension, termedasymmetrical LMC, which occurs when egg laying by females ona patch is asynchronous, and emerging males do not disperse,resulting in the extent of LMC on a patch varying over time.Our aim here is to test whether the parasitoid wasp Nasoniavitripennis responds to variation in the degree of asymmetricalLMC. Specifically, we show that females adjust their offspringsex ratios in response to (1) variation in the amount of asynchronyin emergence between broods on a patch and (2) the number andproportion of previously parasitized hosts on the patch. Ourresults provide qualitative support for the predictions of theory,suggesting new levels of complexity in the sex ratio behaviorof this much-studied organism. However, our results do not alwaysprovide quantitative support for theory, suggesting furthercomplexities that must be clarified.     

Cytotoxic and antiprotozoal activity of flavonoids from Lonchocarpus spp.

A number of flavonoids isolated from Lonchocarpus spp. were evaluated for their antiprotozoal and cytotoxic activity. Flavone 6 and chalcone 7 were found to be the most active against Leishmania parasites and against cell cultures of Leukemia P388DI and adenocarcinoma prostate PC-3.