Molecular identification of iridoviruses infecting various sturgeon species in Europe.

Iridoviridae are known to cause disease in sturgeons in North America. Here, histological and molecular methods were used to screen for this family of virus in sturgeons from various European farms with low-to-high morbidity. Some histological samples revealed basophilic cells in the gill and labial epithelia, strongly suggesting the accumulation of iridovirus particles. Newly developed generic PCR tests targeting the major capsid protein (MCP) gene of sturgeon iridoviruses identified in North America, namely the white sturgeon iridovirus and the Namao virus (NV), produced positive signals in most samples from four sturgeon species: Russian (Acipenser gueldenstaedtii), Siberian (A. baerii), Adriatic (A. naccarii) and beluga (Huso huso). The sequences of the PCR products were generally highly similar one another, with nucleotide identities greater than 98%. They were also related to (74-88%), although distinct from, American sturgeon iridoviruses. These European viruses were thus considered variants of a single new virus, provisionally named Acipenser iridovirus-European (AcIV-E). Moreover, three samples infected with AcIV-E showed genetic heterogeneity, with the co-existence of two sequences differing by five nucleotides. One of our European samples carried a virus distinct from AcIV-E, but closely related to NV identified in Canada (95%). This study demonstrates the presence of two distinct sturgeon iridoviruses in Europe: a new genotype AcIV-E and an NV-related virus.

Development of a radioimmunoassay for aprindine.

We have developed a radioimmunoassay for aprindine, a new antiarrhythmic drug used in the treatment of ventricular disorders. The antibodies were produced by immunization of New-zealand rabbits with aprindine coupled to human serum albumin. Their biochemical characteristics have been determined. Tritiated aprindine was used as radioactive competitor. The cross-reactivity with several metabolites of aprindine was studied too. Finally, the results obtained by RIA in plasma and tissues of dogs were compared to those obtained by gas-chromatography.

The uptake of cardiac glycosides by intestinal smooth muscle of the guinea-pig in relation to digitalis receptors.

1. The accumulation and release of (3)H-digitoxin, (3)H-digoxin and (3)H-ouabain by isolated guinea-pig intestinal smooth muscle has been studied and compared with a pharmacological action due to inhibition of the sodium pump.2. The uptake of labelled cardiac glycosides can be described by means of an exponential function. The t of uptake was similar for the three compounds and did not depend on the concentration.3. Analysis of the curve relating the uptake of cardiac glycosides at equilibrium to the bath concentration enabled a non-saturable and a saturable binding site to be distinguished.4. In contrast to the uptake observations, the onset of the pharmacological effect was dependent on the concentration, and furthermore the t((1/2)) for this effect was shorter.5. The release of cardiac glycosides proceeded more slowly than the uptake.6. The uptake of a labelled glycoside was reduced in the presence of another glycoside. The amount of displaceable glycoside was nearly equivalent to the capacity of the saturable binding site.7. The significance of these results is discussed.

The uptake of cardiac glycosides in relation to their actions in isolated cardiac muscle.

1. The uptake of (3)H-digitoxin, (3)H-ouabain and (3)H-dihydro-ouabain by isolated guinea-pig atria has been studied and compared with the inhibition of the sodium pump and with the inotropic effect.2. Analysis of the curve relating the uptake of digitoxin and ouabain at equilibrium to the bath concentration enabled a non-saturable and a saturable binding site to be distinguished.3. The uptake of inactive doses of dihydro-ouabain was only by a non-saturable mechanism.4. The uptake of labelled digitoxin and ouabain was reduced in the presence of another glycoside. The amount of bound glycoside was nearly equivalent to the estimated non-saturable uptake.5. The uptake was reduced at 4 degrees C to the clearance of the non-saturable site.6. ED50 of digitoxin and of ouabain for inhibition of the sodium pump were measured and compared to the ED50 for inotropic effect and to the concentrations producing a half-saturation of the saturable binding site.7. It is concluded that binding to the saturable site may be responsible for the cardiac actions of the glycosides.

Benzodiazepine receptors are involved in tabernanthine-induced tremor: in vitro and in vivo evidence.

Tabernanthine, an indol alkaloid, is structurally related to carbolines (harmane, harmaline) which, in vitro, displace specific flunitrazepam binding to brain benzodiazepine receptors. In vivo, both tabernanthine and carbolines cause a fine general tremor, suggesting that a possible interaction with benzodiazepine receptors could be involved in the activity of tabernanthine. This hypothesis was validated by the in vitro and in vivo antagonism of benzodiazepine by tabernanthine. In vitro, tabernanthine inhibited specific flunitrazepam binding in a competitive manner with an affinity (IC50 150 microM) in the same range as harmane. Tabernanthine appeared as a benzodiazepine receptor inverse agonist in a discriminant in vitro binding assay. In vivo, the time course of tremorigenic activity was related to the tabernanthine concentration in brain (half-life = 2 h). Moreover, tabernanthine-induced tremor was inhibited reversibly by flunitrazepam or by Ro-15 1788 (an antagonist of benzodiazepine-receptors). These results suggest that part of the action of tabernanthine may be mediated by an interaction at the benzodiazepine receptor level.

The quantification of gamma-aminobutyric acid in the cerebrospinal fluid by a radioreceptorassay.

The development of a radioreceptor assay designed to measure gamma-aminobutyric acid (GABA) in CSF is described. The method is based on the presence of high affinity and selective GABA binding sites obtained from rat brain membrane preparations treated with 0.05% Triton X-100. The optimum protein concentration in the incubation medium, the duration of incubation to reach equilibrium, the temperature and the optimum pH are discussed. The standard curve permits measurements in the range 35 to 2250 nmol/l GABA. The imprecision of the method calculated from three different concentrations: 1125, 562 and 281 nmol/l shows coefficients of variation for 'within' and 'between' assays, between 5.2% and 9.3% and between 7.4% and 12.4%, respectively. The percentage of recovery is 102 +/- 3.3% (n = 4). This radioreceptorassay has a sensitivity of 14 nmol/l. The method is easy, rapid and not expensive. It enables analysis of small volumes of CSF (200 microliters). Several samples (greater than 20) can be analysed in the same run in about one hour.

Degradation of doxorubicin and daunorubicin in human and rabbit biological fluids.

The stability of doxorubicin (DOX) and daunorubicin (DNR) in rabbit and human plasma, bile and urine and in rabbit faeces was studied in the presence or absence of light, and at body, room and cold room temperatures. Fluorescence was determined by spectrofluorimetry after normal and reversed phase HPLC. Under each set of conditions, DOX and DNR fluorescence decreased with time; the decrease was more rapid with DOX. As the parent drugs were degraded, apolar compounds were formed which behaved like 7-deoxyaglycones and generally did not compensate for the loss in fluorescence of the parent drug. The degradation of anthracyclines occurred even in the absence of light, was not due to bacterial contamination and was faster at higher pH or temperature. The rapid degradation of DOX and DNR in biological fluids at body temperature may have implications on the disposition of anthracyclines in vivo. Prior to analysis, biological fluids and solutions containing anthracyclines should be processed quickly at 4 degrees C, in the absence of light, and at a pH no greater than 6 to avoid degradation.

Hepatic clearance of gitoxin: pharmacokinetic study on rabbit isolated liver. Influence of protein binding and comparison with digoxin.

Hepatic clearance of gitoxin has been studied in the rabbit and compared with that of digoxin using an isolated perfused liver technique. During 1.5 hour perfusions with a modified Krebs-Henseleit solution, gitoxin perfusate levels decreased biexponentially; the distribution and elimination half-lives were estimated to be 0.14 and 1.25 hour, Vd area to be 95.5 ml.g-1 and intrinsic metabolic clearance to be 1.98 ml.min-1.g-1. During 1.5 hour perfusions with modified Krebs-Henseleit solution containing 2.7% bovine serum albumin, gitoxin perfusate levels decreased monoexponentially. This is probably due to protein binding which moderates hepatic uptake so that distribution is not yet complete after 1.5 hour and it is therefore impossible to discriminate the two phases. This was confirmed by 5 hour perfusion experiments with an emulsion of perfluorocarbon in the modified Krebs-Henseleit solution also containing 2.7% bovine serum albumin, during which gitoxin levels decreased biexponentially. Distribution and elimination half-lives have been estimated to be 0.31 and 5.54 hours, Vd area to be 139 ml.g-1 and intrinsic metabolic clearance to be 1.36 ml.min-1.g-1. Gitoxin has been compared in these experimental conditions with digoxin, one of the most often used cardiotonic's. Distribution and elimination half-lives of digoxin were estimated to be 0.34 and 4.52 hours, Vd area to be 46.5 ml.g-1 and intrinsic metabolic clearance to be 0.17 ml.min-1.g-1. Other pharmacokinetic parameters (alpha, beta, V1, V2...) also have been calculated for these three types of perfusion experiments.

A further study of the pharmacokinetics of gitoxin in rabbit isolated liver: clearance of 3H-gitoxin.

Hepatic clearance of 3H-gitoxin was studied in the rabbit using an isolated perfused liver technique with an emulsion of a perfluorocarbon. The liposoluble material in the perfusion medium was extracted with dichloromethane, and gitoxin was assayed in the extract by high performance liquid chromatography. Pharmacokinetic parameters were estimated for the liposoluble (dichloromethane soluble) material in the water phase obtained by centrifugation of the emulsion, for the liposoluble material and unchanged gitoxin in the total emulsion. Distribution and elimination half-lives of the liposoluble fraction in the water phase, were estimated to be 0.47 and 4.80 hours respectively, Vd to be 148 ml.g-1 and intrinsic clearance to be 1.16 ml.min-1.g-1; these parameters were compared with those of a previous study with unlabelled gitoxin. Distribution and elimination half-lives of the liposoluble compounds in the emulsion were estimated to be 0.48 and 4.62 hours, Vd to be 47 ml.g-1 and intrinsic clearance to be 1.07 ml.min-1.g-1; these data were compared with those of the liposoluble compounds in the water phase. Distribution and elimination half-lives of unchanged gitoxin in the emulsion were estimated to be 0.22 and 0.70 hour, Vd to be 59 ml.g-1 and intrinsic clearance to be 11.4 ml.min-1.g-1; these data were compared with those of the liposoluble compounds in the emulsion. The subcellular distribution of gitoxin and its metabolites in the liver indicated that 79% of the radioactivity was found in the soluble fraction, no significant binding occurring in the mitochondrial and microsomal fractions.

Irreversible binding to proteins after single and repeated daily oral administration of 4-(2,2-diphenylethyl) imidazole (SC-46264) to the Cynomolgus monkey.

SC-46264 is an antagonist of the alpha 2-adrenergic receptor. Distribution and excretion of [14C]-SC-46264 were studied after single and repeated daily oral administrations to the Cynomolgus monkey at a 1.5 mg/kg dose. After a single oral administration, more than 95% of the administered dose was recovered within 48 h in the urine (+/- 60%) and faeces (+/- 40%). Approximately 1.7% remained in the gastro-intestinal (GI) tract and 2% in the animal body. However, the radioactivity remaining in the animal body decreased very slowly from 2 to 1% between 48 and 144 h. An accumulation of very small amounts of radioactivity could be suspected in the plasma, the liver, the thyroid, the adrenals and the kidneys. In a 2 week daily oral administration of [14C]-SC-46264, the amount of total radioactivity remaining in the animal body 24, 48 and 216 h after the last administration was approximately 21, 11 and 5% of the daily administered dose, respectively. It confirmed the accumulation of [14C]-SC-46264 related compound in the plasma, the liver, the thyroid, the adrenals and the kidneys. The minimum plasma concentrations of total radioactivity observed before each administration increased during the treatment and apparently did not yet reach an equilibrium after 14 days. In these plasma samples obtained throughout the study, an increasing fraction of the total radioactivity could not be extracted and was recovered with precipitable material. These observations lead to the hypothesis of an irreversible binding of some material to the proteins.(ABSTRACT TRUNCATED AT 250 WORDS)

[Placental sulfatase deficiency and sex-linked recessive ichthyosis. Two cases found in two sisters (author's transl)]. / Déficit en sulfatase placentaire et ichthyose récessive liée au sexe. Deux cas observés chez deux soeurs.

The diagnosis of placental sulfatase deficiency was made at the same time in two sisters who were pregnant. This is the first case history reported of two women who were carriers of this abnormality and who were linked by parentage. The inborn error of metabolism was able to be found in its post-natal state in two of the sons of one of the women in the form of retention cutaneous ichthyosis of a sex-linked type.