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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 (Ac IV-E). Moreover, three samples infected with Ac IV-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 Ac IV-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 Ac IV-E and an NV-related virus. [ABSTRACT FROM AUTHOR]

Carp edema virus disease (CEVD) is a severe viral illness that causes substantial economic losses in wild and farmed common carp and koi. It is caused by carp edema virus (CEV), a member of the Poxviridae family , whose genetic diversity and genome evolution are poorly understood. Based on a genomic fragment of the 4a gene, two genogroups, genogroup I (gI) and genogroup II (gII), have been identified in samples of different origins. By analysing a series of recent samples, we highlight here a new genomic region of interest that varies by substitutions, indels and putative recombinations. In the Japanese reference sequence, this region encodes an ORF, cds46, whose function is unknown despite weak homologies with genes of some members of the Iridoviridae . Surprisingly, AlphaFold protein structure prediction analyses link cds46-encoded ORF with cellular endonucleases, providing insights into its possible origin. The ORF is absent in all gI haplotypes and in some gII haplotypes. Apart from the absence of cds46, gI haplotypes show an insertion of 121 bp with no homology to any viral sequence. When present, cds46 showed two groups of alleles differentiated by substitutions. The analysis of the cds46 locus showed that some samples from fish batches contained mixes of different haplotypes, irrespective of their origin (i.e. France, Japan or Israel). In a 2023 sample, we also found a virus carrying a gII-like atypical 4a allele first identified in France in 2015, indicating the limited but persistent spread of this virus in the country. The cds46 locus is a new target that may be useful for identifying and tracking CEV haplotypes.

To develop a library-dependent method of tracking fecal sources of contamination of beaches on the Atlantic coast of southwestern France, a library of 6368 Escherichia coli isolates was constructed from samples of feces, from 40 known human or animal sources collected in the vicinity of Arcachon Bay in 2010, and in French Basque Country, Landes, and Béarn, between 2017 and 2018. Different schemes of source identification were tested: use of the complete or filtered reference library; characterization of the isolates by genotypic or proteomic profiling based on ERIC-PCR or MALDI-TOF mass spectrometry, respectively; isolate by isolate assignment using either classifiers based on the Pearson similarity or SVM (support vector machine). With the exception of one source identification scheme, which was discarded since it used self-assignment, all tested schemes resulted in low rates of correct classification (<35%) and significant rates of incorrect classification (>15%). The heterogeneous coverage of E. coli genotypic diversity between sources and the uneven distribution of E. coli genotypes in the library likely explain the difficulties encountered in identifying the sources of fecal contamination. Shannon diversity index of sources ranged from 0 for several wildlife species sampled once to 3.03 for sewage treatment plant effluents sampled on various occasions, showing discrepancies between sources. The uneven genotypic composition of the library was attested by the value of the Pielou index (0.54), the high proportion of nondiscriminatory genotypes (>91% of the isolates), and the very low proportion of discriminatory genotypes (<3%). Since efforts made to constitute such a library are not affordable for routine analyses, the results question the relevance of developing such a method for identifying sources of fecal contamination on such a coastline.

Acipenser iridovirus-European (AcIV-E) is an important pathogen of sturgeons. Two variants differing by single-nucleotide polymorphisms (SNP) in the Major Capsid Protein gene have been described, but without any indication as to their prevalence in farms. To facilitate epidemiological studies, we developed a high-resolution melting (HRM) assay to distinguish between two alleles (var1 and var2) differing by five point substitutions. The HRM assay detected as little as 100 copies of plasmids harboring cloned sequences of var1 and var2, which have melting temperatures (Tm) differing by only 1 °C. The assay was specific of AcIV-E as demonstrated by the absence of signal when testing a related, yet distinct, virus as well as DNA from an AcIV-E-negative sturgeon sample. Experiments with mixtures of two distinct plasmids revealed abnormal melting curve patterns, which showed dips just before the main melting peaks. These dips in the curves were interpreted as the dissociation of heteroduplexes fortuitously created during the PCR step. Screening AciV-E-positive field samples of Russian sturgeons from three farms revealed the presence of var2, based on the Tm. However, for a few samples, the melting curves showed patterns typical of var2 as the dominant viral genome, mixed with another minor variant which proved to be var1. In conclusion, HRM is a simple method to screen for AcIV-E var1 and var2 and can be used on a large scale in Europe to trace these two variants which likely represent two genetic lineages., (Copyright © 2018 Elsevier B.V. All rights reserved.)

New genomic sequence data were acquired for the Acipenser iridovirus-European (AcIV-E), a virus whose complete genome and classification still remain to be elucidated. Here, we obtained the first full-length Major capsid protein (MCP) gene sequence for AcIV-E, as well as two additional open reading frames (ORFs) adjacent to the MCP gene. BLAST searches of the first ORF (α) resulted in no match to any gene or protein in the public databases. The other ORF (β) was identified as a subunit of a replication factor C (RFC), known to function as a clamp loader in eukaryotes, archae and some viruses. The presence of similar RFC genes was confirmed in two distinct, yet related, viruses, the white sturgeon iridovirus and a European variant of Namao virus. The existence of an RFC gene in AcIV-E suggests a genome size larger than that of other classifiable members of the family Iridoviridae along with a mode of replication involving an interaction between a clamp loader and a proliferating nuclear cell antigen. Sequencing and comparison of the full-length RFC gene from various sturgeon samples infected with AcIV-E revealed two distinct clusters of sequences within one particular sample in which the coexistence of two lineages had previously been predicted based on analysis of the partial MCP gene sequence. These genetic data provide further evidence of the circulation of at least two concurrent AcIV-E lineages, sometimes co-infecting cultured European sturgeon.

1. The metabolism of SC-42867 and SC-51089, two PGE2 antagonists, was studied in cultured rat and human hepatocytes. Both compounds possess an 8-chlorodibenzoxazepine moiety, but differ from each other by the nature of the side chain connected to the nitrogen atom. SC-42867 and SC-51089 and their in vitro metabolites were separated by reversed-phase hplc. The major metabolites of both compounds were identified by mass spectrometry (ms) analysis. 2. SC-42867 was metabolized on the tricyclic moiety only. Oxidative N-dealkylation with opening of the oxazepine ring was the major metabolic pathway obtained in rat hepatocytes. The metabolic profile obtained in cultured human hepatocytes was comparable with that of cultured rat hepatocytes. However, the compound was metabolized to a much lower extent by the human cells. 3. SC-51089 was extensively metabolized by both cultured rat and human hepatocytes. Human cells metabolized this compound quite differently than cultured rat hepatocytes. Aromatic hydroxylation with consequent glucuronidation and sulphation were the main metabolic pathways observed in cultured human hepatocytes. Oxidative N-dealkylation with opening of the oxazepine ring and consequent glucuronidation was the major metabolic pathway observed in rat hepatocytes. Further metabolism occurred, in contrast with the human hepatocytes, mainly on the side chain. 4. The present in vitro results are compared with data of previous in vivo studies performed in rat.

Kinetics and metabolism of 3H-gitoxin were determined in the guinea-pig after the i.v. administration of 80 microgram gitoxin/kg. The time course of plasma concentration and urinary amounts remaining to be excreted were described according to the three-compartment linear body model. Apparent half-lives of 4.98 +/- 0.16 hr (plasma) and 24.0 +/- 0.5 hr (urine) were found according to the CH2Cl2-soluble radioactivity. The apparent volume of central compartment and the apparent volume of distribution were estimated with 0.44 +/- 0.05 l/kg and 14.33 +/- 1.131/kg respectively. During 96 hr, approximatively 5.3% of the radioactivity given were eliminated via the kidneys whereas almost 78.7% were recovered in faeces. In animals with bile-duct cannulated, approximatively 82.6% of the dose given were excreted in bile during 6 hr. The hepatic degradation of gitoxin was so fast that almost 70% of the radioactivity recovered in plasma, urine and bile samples after 2 hr could no longer be extracted by dichloromethane. In the lipophilic extracts diginatin and its derivatives were found as possible metabolites of gitoxin. At least four polar metabolites hardly hydrolysable by beta-glucuronidase and by arylsulfatase were detected by TLC in the aqueous extracts from the gastro-intestinal excretions.

The aim of the first part of this work is to present elements of hepatic cytology and physiology in order to demonstrate the organisation of the liver for the metabolisation of drugs: the cytology of hepatocytes, their arrangement in the parenchyma, the hepatic microvascularisation, the distribution of the metabolic reactions in the hepatic acinus and the structure of the biliary tract involved in the elimination of some metabolites. 2. The second part is devoted to the concept of hepatic clearance. A few considerations are presented about physiological aspects (hepatic uptake), followed by a more extensive chapter about pharmacokinetics. The following points are explained: mathematical terms of clearance, physiological models, hepatic first-pass effect, influence of the hepatic clearance on half-life of a drug and area under the curve of concentration versus time, the use of clearance or half-life as index of hepatic metabolism and a classification of the drugs in correlation with their hepatic clearance. 3. The conclusions present some contradictions and unresolved points persisting, at the present time, in the hepatic clearance theories and propose new approaches for future investigations.

The aim of the present investigation was to reevaluate the pharmacokinetic and pharmacodynamic parameters of gitoxin in man. Gitoxin given as a solution is quasi-completely absorbed after oral administration in a fasting man. A dose of 1.5 mg modifies the left ventricular ejection time index (LVETI) as digoxin or digitoxin does. The biological half-life of gitoxin calculated on the basis of plasma concentrations or urinary data is about one day. The urinary elimination of gitoxin is smaller than 21% of the dose. Therefore the two main advantages of gitoxin versus digoxin or digitoxin are: 1) its short biological half-life and 2) its elimination being less dependent on the renal function of the patient.

Administration of SC4453 (30 micrograms/kg) in the guinea-pig increases the rate of urinary excretion from 35 ml/kg/24 h to 55 ml/kg/24 h. Ligature of ureters modifies parameters of SC4453 ; t 1/2 beta increases from 4.2 h to 5.6 h and the body clearance diminishes from 622 ml/h/kg (normal guinea-pig) to 530 ml/h/kg in the ligatured ureters guinea-pig. Analysis of the radioactive material excreted in the urine after administration of tritiated SC4453 shows that 58.4% is dichloromethane (DCM) soluble and 41.6% is water soluble. Thin layer chromatography (TLC) of the DCM soluble fraction shows that 74.0% is unchanged SC4453 . After enzymatic hydrolysis of the water soluble fraction, it is shown that 28% is again extractable by DCM of which 57% consists of unchanged SC4453 which is therefore the main partner of conjugated products. Following an i.v. injection of tritiated SC4453 , only 17% of the dose was recovered in urine, against 14% after an intragastric administration. Gastro-intestinal absorption of SC4453 was estimated to be 82.2%.

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.