Anti-proliferative effect of 20-hydroxyecdysone in a lepidopteran cell line.

Ecdysteroids are steroid hormones involved in the epidermal growth of arthropods, controlling cell proliferation and further differentiation of target cells. The epidermal cell line IAL-PID2, established from imaginal discs of the Indian meal moth Plodia interpunctella kept its sensitivity to ecdysteroids in vitro, cells being able to respond to them by cytological and biochemical changes. When added to the culture medium, 20-hydroxyecdysone (20E) stopped cell proliferation and induced formation of epithelial-like aggregates.

Sample handling for proteome analysis.

The main factor limiting the sensitivity range for the identification of proteins isolated by two-dimensional (2-D) electrophoresis is sample handling: protein detection limits on the gel, losses during extraction and digestion, as well as interference of gel contaminants and detergents with the mass spectrometry (MS) detection increasing background noise. At the one hundred picomole level, losses are fairly negligible but when the amounts drop below 1 picomole (and subfemtomole peptide detection limits have been reported recently by MS), the losses become a critical point. In order to extend proteome analysis to include very low copy number proteins, methods must be developed to minimize losses and handling steps, maximize digestion and extraction yields, as well as to lower chemical noise.

Activity of insulin growth factors and shrimp neurosecretory organ extracts on a lepidopteran cell line.

Ecdysteroids, or molting hormones, have been proven to be key differentiation regulators for epidermal cells in the postembryonic development of arthropods. Regulators of cell proliferation, however, remain largely unknown. To date, no diffusible insect peptidic growth factors have been characterized.

Roles for insulin and ecdysteroids in differentiation of an insect cell line of epidermal origin.

During postembryonic development of insects, molting cycles affect epidermal cells with alternate periods of proliferation and differentiation. Cells of the cell line established from imaginal discs of the Indian meal moth (IAL-PID2) differentiate under the action of the molting hormone, 20-hydroxyecdysone, in a manner that is meaningful in terms of the development of the tissue from which they were derived. In particular, the hormone caused an accumulation of the cells in the G2 phase of their cycle and induced the formation of epithelial-like aggregates and the synthesis of specific proteoglycans.

Effects of dexamethasone in a model of lung hyperresponsiveness in the rat.

In rats, Sephadex treatment on days 0, 2 and either 4 or 5 resulted in a blood and lung eosinophilia, an increase in lung cell fragility, an increase in the functional activity of peritoneal eosinophils in vitro and a sustained increased responsiveness of lung parenchymal strips to KCl, 5-hydroxytryptamine (5-HT) and carbachol that was not associated with oedema or gross fibrosis. The corticosteroid dexamethasone, when given before each injection of Sephadex, reduced all these effects of Sephadex. When given 30 min after the last injection of Sephadex, dexamethasone had no effect on the number of blood and lung eosinophils but it did reduce the functional activity of peritoneal eosinophils, the increased lung cell fragility and the hyperresponsiveness to 5-HT.

Cardiac ultrastructural abnormalities in Syrian hamsters with spontaneous cardiomyopathy or subjected to cardiac overloads.

Ultrastructural and morphometric abnormalities of Syrian hamster cardiomyopathy were compared to those observed in two different models of cardiac hypertrophy produced by mechanical overload (abdominal aortic stenosis, 60-day duration) or by isoproterenol injection during 15 days in normal Syrian hamsters of the same strain. Aspects of increased protein synthesis were observed in all three groups of animals. This was the only abnormality observed in the aortic stenosis group.

The effects of drugs on Sephadex-induced eosinophilia and lung hyper-responsiveness in the rat.

1. Rats given an intravenous injection of Sephadex particles (0.5 mg of G200 in 1 ml of saline) on days 0, 2 and 5 had a blood eosinophilia which was maximal on day 7.

Relationship of myocardial morphometry in aortic valve regurgitation to myocardial function and post-operative results.

In 24 patients with aortic insufficiency undergoing aortic valve replacement, a clinical and hemodynamic study was performed pre-operatively. Left ventricular biopsies were obtained perioperatively for morphometric study. No significant relations were found when morphometric data were compared to functional class, cardiothoracic radio and ECG findings.

Morphological approach to the mechanism of heart failure.

From the ultrastructural aspects of the myocardial cell in different types of heart overloading, several points concerning the nature of the myofibrillar changes, the changes in volume, number and size of mitochondria, and the dependence of cellular lesions on the severity of the load were discussed.

Changes in leucocyte numbers without diapedesis in rats given platelet-activating factor (PAF-acether).

Changes occurring in the blood and the peritoneal cavity following the intraperitoneal injection of platelet-activating factor (PAF-acether) into rats were compared with those when antigen was injected intraperitoneally into actively sensitised rats. A blood eosinophilia had been produced in the rats by an intravenous injection of Sephadex G200 6 days before either challenge. 5 min after PAF-acether, the total number of cells in the peritoneal washings had decreased and the concentration of extravasated dye-labelled plasma protein had increased with no change in histamine levels.

[Influence of preload on myocardial relaxation in the rat].

Preload, which determines the initial muscle length, has proved to be a basic determinant of the muscle relaxation phase. The mechanical properties of the papillary muscle of Wistar rats (n = 20) were studied at different initial lengths (L): Lmax and 98 p. 100, 94 p.

Relationship between inotropy and relaxation in rat myocardium.

Myocardial mechanics of 56 rat papillary muscles were investigated in various inotropic states, i.e., early postpartum (1st day, 1st mo) and, in adult, by altering external calcium concentration, [Ca2+]0, stimulation frequency (F), and initial muscle length (L).

[Absence of ultra-structural histological lesions of the myocardium in cardiac insufficiency of hyperthyroidism].

Myocardial failure may complicate hyperthyroidism. Some authors consider that preexisting myocardial lesions are necessary for its development. We studied a case of myocardial failure, presenting as a dilated cardiomyopathy, complicating hyperthyroidism in a 57 year old woman.

Effect of drugs on the increase in cell numbers in the peritoneal cavity of the actively sensitised mouse after intraperitoneal challenge with antigen.

The injection of antigen into the peritoneal cavity of actively sensitised mice produced an increase in the number of neutrophils in peritoneal washings collected 4 h later but after 1 day the numbers had returned to control levels. The increase in numbers of mononuclear cells and eosinophils in the peritoneal washings peaked at 2 days and persisted for at least 5 days. Dosing the mice with phenidone, a dual inhibitor of the cyclo-oxygenase and lipoxygenase pathways of arachidonic acid metabolism, potentiated the neutrophil infiltration at 4 h but had no significant effect upon the subsequent mononuclear cell and eosinophil infiltration.

Real-time kinetics of sarcomere relaxation by laser diffraction.

Kinetics of sarcomere movement were studied in real-time by laser diffraction. Instantaneous sarcomere shortening was measured during afterloaded twitches simultaneously with instantaneous shortening and tension of the whole trabecula excised from rat right ventricle. Resting sarcomere length at optimal length was 2.

Relaxation of mammalian heart muscle during chronic cardiac overload.

Cardiac relaxation was studied in rat papillary muscle during hypertrophy induced by different chronic volume and/or pressure overload (aortic insufficiency, aorto-caval fistula, aortic stenosis, spontaneously hypertensive rat). Maximum velocity of lengthening did not depend upon the degree of cardiac hypertrophy, but rather on the type of chronic overload. Cardiac hypertrophy did not modify the load sensitivity of relaxation, whatever the type and stage of chronic overload, although, during acute hypoxia, the load sensitivity disappeared both in normal and in hypertrophied heart muscle.

Myocardial cell nucleus in cardiac overloading in the rat.

The myocardial cell nucleus was studied in the rat during its normal growth and under different types of heart overloading. Under overloading of short duration, a disappearance of condensed chromatin and an increase in the nucleolus and nucleolonema were interpreted as representing cell overactivity. With isoproterenol overloading, a first stage of cell necrosis and of its consequences on chromatin and nucleolus was followed by the process of cell repair and overactivity.

Lithium causing a serious sinus-node dysfunction at therapeutic doses.

The cardiovascular effects of lithium have been indexed in literature since 1900, most frequently in cases of intoxication. We recently studied the exceptional case of a patient showing a serious sinus node dysfunction during lithium treatment. The serum lithium levels were always within the therapeutic range.

[Cardiac relaxation in experimental chronic myocardial hypertrophy: role of the sarcoplasmic reticulum].

The relaxation phase was studied in normal rat hearts submitted to chronic myocardial pressure and/or volume overload (stenosis of the abdominal aorta, aortic regurgitation, aorto-caval fistula) and in spontaneously hypertensive rats, some of which also had aorto-caval fistulae. Four indices were chosen to quantify the relaxation phase: maximal velocity of relaxation during contraction with preload alone, the negative peak of the derivative of isometric tension, and two other indices testing the sensitivity of the relaxation phase to other conditions of load. The first two indices were found to be depressed during chronic myocardial overload, especially with aorto-caval fistulae and mixed overload.

Serious sinus node dysfunction caused by therapeutic doses of lithium.

We studied an exceptional case of a patient showing serious sinus node dysfunction during lithium treatment with levels constantly within the therapeutic range. After two endocardial explorations we found that the sinus node dysfunction was due to lithium and reversible after its withdrawal.

[The use of lasers in the study of cardiac mechanics].

Cardiac and skeletal muscles exhibit regularly spaced light and dark transverse striations (the I and A bands respectively). Consequently, when they are illuminated by a laser beam, they behave like diffraction gratings. The diffraction line spacing varies inversely with the sarcomere length.

Force-velocity-length relationship during cardiac hypertrophy. Time course of activation.

Basic mechanical properties observed during cardiac hypertrophy were studied in left ventricular rat papillary muscles after exposure to chronic pressure and/or volume overloading. It is always possible, during such overloading conditions, to define the level of contractility in terms of a force-velocity-length (F-V-L) relationship regardless of time and initial length. Thus, during a determined period of the contraction phase and for a given total load, shortening velocity remained an univocal time-invariant function of shortening length, involving a time-independent maximum intensity of activation.

Nonsympathetic increased inotropic state early after aortic insufficiency.

The very early left ventricular response to chronic volume overload induced by aortic insufficiency (AI) was examined in conscious dogs previously instrumented with a left ventricular micromanometer and ultrasonic crystals measuring internal diameter, segmental length, and parietal wall thickness. Acute volume loading with dextran (AVL) was compared with that 24 and 48 h after AI induced by a perforation of the aortic valve. beta-Blockade was also produced before and after AI.

Load dependence of mammalian heart relaxation during cardiac hypertrophy and heart failure.

Mechanical properties of relaxation were studied in left ventricular rat papillary muscle during cardiac hypertrophy induced by chronic pressure and/or volume overload. Maximum velocity of isotonic lengthening was linearly related to total extent of isotonic shortening and to maximum velocity of isotonic contraction and depended on the type of chronic overloading without correlation with the degree of cardiac hypertrophy. Time to peak shortening was significantly increased in each group of hypertrophied heart muscles as compared to controls.