Origin of ammonia excreted by trout gill (Salmo gairdneri)]

In the perfused head of Trout the gills are the site of ammonia clearance which corresponds exactly to the appearance rate of ammonia in the external medium. Thus metabolic production of ammonia by the gill apparently does not participate to its excretion. Under ammonia-free Ringer perfusion however, endogenous production is observed and ammonia is excreted in both external and internal media.     

Adenosine promoted accumulation of adenosine 3',5'-monophosphate in rabbit vagus nerve.

Desheathed rabbit vagus nerve has been found to form cyclic AMP when incubated with adenosine. This accumulation of cyclic AMP is inhibited by theophylline but not by antiadrenergic agents, anticholinergic agents or local anaesthetics. Depolarizing media are not able to promote cyclic AMP accumulation in this preparation.     

Isolation of a pathogenic rhabdovirus of brown trout (Salmo trutta L., 1766)]

A Rhabdovirus pathogenic both for Rainbow and Brown Trout has been isolated from Brown Trout suffering heavy mortalities associated with muscular haemorrages and necrotic lesions of kidney and spleen. According to seroneutralization tests and host range, this virus appears to be different from the other known salmonids rhabdoviruses. Upon the basis of its in vitro gross characteristics, it is identical to Viral Haemorragic Septicemia Virus (VHS), F1 serotype, but differs from Infectious Hematopo?etic Necrosis and VHS type II viruses.     

Histochemical localization of lactate dehydrogenase in the trout embryo (Salmo irideus, Gibb) during early organogenesis of the cord and the neural tube]

The histochemical study of the LDH in the Trout embryo during the early organogenesis shows a specific localization in notochord cells, in mesodermic cells of the terminal knob and in some prosencephalic neuroblasts. The role of the LDH in the metabolism of NAD as well as in the energetic metabolism of embryonic cells is discussed.     

Stimulation of the synthesis and non-competitive inhibition of alkaline phosphatase by theophylline in normal hamster fibroblasts and absence of response in transformed fibroblasts]

Theophylline increases the synthesis of alkaline phosphatase in normal Hamster fibroblasts (activity X6 after 24 hours with theophylline 10-3 M). The enzymatic activity of these cells is inhibited by theophylline in vitro (80% inhibition in the presence of theophylline 10-3 M). The inhibition seems to be non competitive, since the apparent Km of the enzyme is not modified. This stimulator and inhibitor effect of theophylline is absent in Hamster fibroblasts transformed by SV 40 virus.     

A new twist to the No Miracles Argument for the success of science

J. D. Trout has recently developed a new defense of scientific realism, a new version of the No Miracles Argument. I critically evaluate Trout's novel defense of realism. I argue that Trout's argument for scientific realism and the related explanation for the success of science are self-defeating. In the process of arguing against the traditional realist strategies for explaining the success of science, he inadvertently undermines his own argument.     

Adenosine promoted accumulation of adenosine 3′,5′-monophosphate in rabbit vagus nerve

Summary Desheathed rabbit vagus nerve has been found to form cyclic AMP when incubated with adenosine. This accumulation of cyclic AMP is inhibited by theophylline but not by antiadrenergic agents, anticholinergic agents or local anaesthetics. Depolarizing media are not able to promote cyclic AMP accumulation in this preparation.Acknowledgment. We gratefully acknowledge Mr.G. Jones for valuable discussion, MrsM. Moosmayer and Mr.S. Ferrara for expert technical assistance and Swiss National Science Foundation for grant support (Nr. 3.478.0.75).     

Modification of theophylline-induced lipolysis in human fat cells after trypsination.

Trypsin-treatment of human fat cells results in the potentiation of the lipolytic response and the cAMP accumulation induced by theophylline (5 . 10(-4) M) but not of those induced by theophylline (5 . 10(-3) M). The amount of cAMP formed after exposure to theophylline (5 . 10(-3) M) plus norepinephrine (5 . 10(-6) M) remains, however, 2.6 fold higher in trypsin-treated human fat cells than in the control ones.     

The effects of sodium and amiloride on the motility of the caudal epididymal spermatozoa of the rat

Summary The forward motility of the rat caudal epididymal spermatozoa has been studied in different Na⁺ concentrations. When spermatozoa were suspended in a completely Na⁺-free solution, the forward motility suffered a progressive fall and after 3 h was completely suppressed. This effect was fully reversible on resuspending the spermatozoa in a solution containing Na⁺. Amiloride caused a fall in motility and the effect was similar to that of Na⁺ removal. The inhibition by amiloride of the motility was concentration dependent and the dose response curve showed an IC₅₀-value of about 5×10^–5 M. The role of Na⁺ influx in the maintenance of sperm motility was discussed.This work was supported by the World Health Organization.The technical assistance of Mr C.M. Li and the gift of amiloride from Merck, Sharp and Dohme are gratefully acknowledged.     

Response of the brown trout (Salmo trutta, L. 1766) and rainbow trout (Salmo gairdneri Richardson, 1836) to infection by a new rhabdovirus]

Intra peritoneal injection of 200 g Trout hold at + 12 degrees C with 2x10(8) p.f.u. of a new Rhabdovirus (strain 23.75) induces an interferon synthesis within 2 days. (IF titres reaching 2,000 units/ml). 1 month later, the surviving Fish exhibit a specific anti 23.75 neutralizing serum activity (titre 40 to 80) which has been demonstrated to be due to immunoglobulins. This seroneutralization is also recorded in 1/3 of the survivors of natural infection.     

Effects of theophylline on chemically induced liver tumorogenesis and on bladder membranes in rats]

The addition of theophylline to the diet of rats given the carcinogen 4-dimethylaminoazobenzene did not significantly impair the development of hepatomas. In contrast, the feeding of theophylline has been associated to some histopathological changes in bladder membrane leading to the occurrence of malignant papillomas.     

The relationship of phosphodiesterase and cyclic AMP to the process of fluid secretion in the salivary glands of the ixodid tick Amblyomma americanum.

Phosphodiesterase (PDE) activity in the salivary glands of the female. Amblyomma americanum decreased as the tick progressed from a slow to a rapid phase of feeding, while the rate of fluid secretion increased when glands were stimulated with cyclic AMP and theophylline. Dopamine stimulated PDE activity and an 'inhibitory' factor was found in glands obtained from rapidly engorging ticks which decreased PDE activity. These findings are discussed as they relate to the process of fluid secretion by salivary glands of feeding ixodid ticks.     

A negative inotropic effect of acetylcholine in the presence of several phosphodiesterase inhibitors

The phosphodiesterase inhibitors papaverine, theophylline and 3-isobutyl-1-methylxanthine (IBMX) reveal a negative inotropic effect of acetylcholine in cat ventricular heart muscle. This effect in unrelated to beta-adrenoceptor stimulation and possibly mediated by the accumulation of cyclic GMP.     

Effects of gastric secretagogues on tissue glycerol in the isolated amphibian gastric mucosa

Histamine and theophylline, two gastric secretagogues, significantly increased tissue glycerol content by 121 and 66%, respectively, in the isolated toad gastric mucosa. This is new evidence in favor of the hypothesis that gastric secretagogues may act via lipid mobilization.     

Cyclic AMP and control of ion exchanges in the fish intestine]

In isolated intestine of the European Flounder, cyclic AMP and theophylline induce a reduction of the negative transmural potential difference and short circuit current, increase severalfold the passive permeability for chloride and abolish the active transport of this ion. These effects are very different from those described in mammals.     

Defining motility in the <Emphasis Type="Italic">Staphylococci</Emphasis>

The ability of bacteria to move is critical for their survival in diverse environments and multiple ways have evolved to achieve this. Two forms of motility have recently been described for Staphylococcus aureus, an organism previously considered to be non-motile. One form is called spreading, which is a type of sliding motility and the second form involves comet formation, which has many observable characteristics associated with gliding motility. Darting motility has also been observed in Staphylococcus epidermidis. This review describes how motility is defined and how we distinguish between passive and active motility. We discuss the characteristics of the various forms of Staphylococci motility, the molecular mechanisms involved and the potential future research directions.     

Modification of theophylline-induced lipolysis in human fat cells after trypsination

Summary Trypsin-treatment of human fat cells results in the potentiation of the lipolytic response and the cAMP accumulation induced by theophylline (5·10^–4 M) but not of those induced by theophylline (5·10^–3 M). The amount of cAMP formed after exposure to theophylline (5·10^–3 M) plus norepinephrine (5·10^–6 M) remains, however, 2.6fold higher in trypsin-treated human fat cells than in the control ones.Acknowledgments. The authors gratefully acknowledge the help of the surgical staff of the C. H. I. of Poissy. This work was supported by grants from the C. H. I. of Poissy and from the Université René Descartes.     

Selection of cell lines resistant to ouabain from murine plasmacytoma MOPC 173. Cross resistance to cyclic AMP, theophylline, and concanavalin A]

Using ouabain as a selective agent, we obtained from a contact inhibited and a non contact inhibited cell layer derived from the same plasmocytoma, different resistant cell lines. All of them were ouabain resistant but were also able to grow in presence of normallly toxic levels of cAMP, theophylline and concanavalin A.     

Reflex motility of the stomach evoked by electrical stimulation of the hepatic vagus nerve

Summary Electrical stimulation of the cranial end of the cut hepatic branch of the vagus nerve produced an increase in the motility of the empty stomach in the rat, whereas systemic injection of insulin produced a gradual increase in the motility.Acknowledgment. The authors are indebted to Dr K. Yamaguchi and Prof. A. Niijima for their encouragement of the project.     

Neuronal responses to extracellularly applied cyclic AMP:Role of the adenosine receptor.

At low doses, theophylline blocks the neuronal depressant effects of 5'-AMP, but not cyclic AMP. Higher doses (100 mg/kg) block cyclic AMP responses and reduce the effects of noradrenaline and GABA. It is concluded that cyclic AMP does not depress neurones via the adenosine receptor.