Phospholipase A2 diversity and polymorphism in European viper venoms: paradoxical molecular evolution in Viperinae.

We report the diversity and polymorphism of phospholipase A(2) (PLA(2)) transcripts from snakes belonging to nine European viper subspecies. This diversity results in the expression of a combination of six PLA(2) species--ammodytin I1, ammodytin I2, ammodytin L, ammodytoxin, vaspin A and vaspin B--with 19 known isoforms of the first five of these species. Most of the European viper venoms studied contained either a myotoxin or a neurotoxin, and all contained ammodytin I1 and ammodytin I2. There is no evidence that a given pattern of PLA(2) species constitutes a taxonomic criterion, and isoform analysis would be required for such discrimination. Analysis of the phylogenetic relationships between PLA(2) species from European vipers and those of other members of the Viperinae revealed a strong correlation between the geographical source of the viper and the clustering seen for the different isoforms, for each PLA(2) species. The K(a)/K(s) values calculated for the mature protein-coding region of paralogous genes showed that ratios for pairs including vaspin B or one ammodytoxin isoform were greater than 1.09, whereas those for most of the remaining pairs were less than 1. Different patterns of mutation were observed in comparisons of the different PLA(2) isoforms. The mechanisms directing a mutation toward a precise exon remain unresolved.

Toxicity evolution of Vipera aspis aspis venom: identification and molecular modeling of a novel phospholipase A(2) heterodimer neurotoxin.

We report the simultaneous presence of two phospholipase A(2) (PLA(2)) neurotoxins in the venom of Vipera aspis aspis, the first such observation. One is monomeric and identical to ammodytoxin B of Vipera ammodytes ammodytes. Its presence may result from gene flux after interbreeding between V. aspis aspis and V. ammodytes ammodytes. The second, a novel heterodimer named vaspin, is very similar to vipoxin of Vipera ammodytes meridionalis and to PLA(2)-I of Vipera aspis zinnikeri. It may result from expression of preexisting genes, the acidic subunit evolving from an ancestor common to ammodytin I2 from V. ammodytes ammodytes, which we also found in V. aspis aspis.

Cardiac multislice spiral computed tomography as an alternative to coronary angiography in the preoperative assessment of coronary artery disease before aortic valve surgery: a management outcome study.

BACKGROUND: Conventional coronary angiography (CA) is still recommended before valvular surgery. Preliminary studies suggest that multislice spiral computed tomography coronary angiography (MSCT-CA) can be used to rule out coronary artery disease (CAD). AIM: To assess prospectively the safety of ruling out CAD before surgery solely on the basis of normal MSCT-CA in patients with severe aortic valve disease. METHODS: We included all consecutive patients scheduled for aortic valve surgery. We first estimated the calcium score (Agatston score equivalent [ASE]). Patients underwent injected MSCT if the ASE was<1000. CA was cancelled when MSCT-CA quality was sufficient and showed no significant CAD. Our primary endpoint was the occurrence of perioperative myocardial infarction in patients who underwent surgery with no prior CA. RESULTS: Between 1st July 2005 and 30th June 2008, we included 199 patients with severe aortic valve disease: 118 men (59%); mean age 69+/-12 years; 63 patients (32%) underwent CA directly because the ASE was > or =1000. Of 136 patients who underwent MSCT-CA, 106 (78%) had a normal MSCT-CA and underwent aortic valve surgery without prior CA; CA was performed in 30 patients because of abnormal (n=18) or bad quality (n=12) MSCT-CA. One patient of the 106 (0.94%, 95% confidence interval 0.17-5.15) had a perioperative myocardial infarction. CONCLUSIONS: When the ASE is <1000, MSCT is safe and may be recommended instead of CA as a first-line means of ruling out CAD in patients with severe aortic valve disease.

Reappraisal of Vipera aspis venom neurotoxicity.

BACKGROUND: The variation of venom composition with geography is an important aspect of intraspecific variability in the Vipera genus, although causes of this variability remain unclear. The diversity of snake venom is important both for our understanding of venomous snake evolution and for the preparation of relevant antivenoms to treat envenomations. A geographic intraspecific variation in snake venom composition was recently reported for Vipera aspis aspis venom in France. Since 1992, cases of human envenomation after Vipera aspis aspis bites in south-east France involving unexpected neurological signs were regularly reported. The presence of genes encoding PLA(2) neurotoxins in the Vaa snake genome led us to investigate any neurological symptom associated with snake bites in other regions of France and in neighboring countries. In parallel, we used several approaches to characterize the venom PLA(2) composition of the snakes captured in the same areas. METHODOLOGY/PRINCIPAL FINDINGS: We conducted an epidemiological survey of snake bites in various regions of France. In parallel, we carried out the analysis of the genes and the transcripts encoding venom PLA(2)s. We used SELDI technology to study the diversity of PLA(2) in various venom samples. Neurological signs (mainly cranial nerve disturbances) were reported after snake bites in three regions of France: Languedoc-Roussillon, Midi-Pyrénées and Provence-Alpes-Côte d'Azur. Genomes of Vipera aspis snakes from south-east France were shown to contain ammodytoxin isoforms never described in the genome of Vipera aspis from other French regions. Surprisingly, transcripts encoding venom neurotoxic PLA(2)s were found in snakes of Massif Central region. Accordingly, SELDI analysis of PLA(2) venom composition confirmed the existence of population of neurotoxic Vipera aspis snakes in the west part of the Massif Central mountains. CONCLUSIONS/SIGNIFICANCE: The association of epidemiological studies to genetic, biochemical and immunochemical analyses of snake venoms allowed a good evaluation of the potential neurotoxicity of snake bites. A correlation was found between the expression of neurological symptoms in humans and the intensity of the cross-reaction of venoms with anti-ammodytoxin antibodies, which is correlated with the level of neurotoxin (vaspin and/or ammodytoxin) expression in the venom. The origin of the two recently identified neurotoxic snake populations is discussed according to venom PLA(2) genome and transcriptome data.