Jeanne Brugère-Picoux

Urodynamic parameters in scrapie-affected ewes and their modifications in the course of the disease.

The aim of this study was to determine the urological abnormalities linked to spontaneous spongiform encephalopathy and their occurrence in the course of the disease. The animals used in this were 11 healthy and 20 scrapie‐affected ewes. The scrapie‐affected ewes were studied at a rate of once a month (1 to 5 measures; mean, 2.55) until they died. Urodynamic explorations were performed. The bladder activity was explored using cystometry. The urethral activity was measured during cystometry and during a urethral pressure profile. Both were analyzed using International Continence Society recommendations. Results showed in scrapie‐affected ewes a decrease in functional bladder capacity and an increase in detrusor contraction incidence during filling of the bladder and in the occurrence of significant urethral instability. Bladder abnormalities were seen only in scrapie‐affected ewes and worsened during the course of the disease. Urethral instability was not typical of the disease but was significantly more frequent in scrapie‐affected ewes. It was concluded that lower urinary tract dysfunction occurred in scrapie‐affected ewes and worsened during the course of the disease. This dysfunction is in agreement with overactive detrusor function due to neurological lesions. Neurourol Urodynam 17:555–563, 1998.

Electroanalytical characterization of Alzheimer's disease and ovine spongiform encephalopathy by repeated cyclic voltammetry at a capillary graphite paste electrode

Abstract Linear sweep voltammetry (sweep rate, 1–10 mV/s) of biological fluids impregnating electrodes made of electrochemically inert compressed graphite powder allows all electrochemically oxidizable compounds which are present in these fluids to be characterized rapidly and cheaply, without preliminary separation, by peaks occurring at specific potentials, and their concentrations to be quantified by the corresponding peak areas or heights. The main components normally present in biological fluids which can be characterized at specific potentials by this electroanalytical technique are ascorbate, urate, xanthin, oxalate, tyrosine, tryptophan, 5-HIAA, VMA, HVA, and some other minor catabolites of catecholamines and serotonin. The oxidation peaks of these components frequently correspond to irreversible oxidations, sometimes generating reversibly oxidizable products which are detected on the first return sweep and in further backward and forward sweeps by a reduction peak which usually occurs at a lower potential than the primary oxidation. The voltammetric profiles obtained for urine samples are remarkably constant when these samples come from healthy patients, but they may undergo substantial quantitative or qualitative alterations with specific features when various types of drugs are administered or pathologies are present. Characteristic features are observed in the urine of patients e.g. after administration of paracetamol, benzodiazepins, opiates and folinic acid. The perfusion of cisplatinum or carboplatinum derivatives results in the formation of a peak which has been attributed to 2, 8-dihydroxyadenine. Strong reductions in the amplitudes of most peaks relating to catabolites which are normally present are observed in urine samples from newborn children. Very strong and sensitive increases in the amplitudes of several peaks appear in urine samples from patients with a variety of inflammatory reactions. Qualitative variations resulting in the formation of peaks which are not normally detected in urine are observed in patients suffering from Alzheimers disease. An epidemiological survey of the correlation between the amplitude of the reduction at 850 mV (vs. the standard hydrogen electrode) on the first return sweep and the clinical indexes in use for the identification of senile dementia have shown that the presence of these electrochemical characteristics is specific for degenerative dementia. Urine samples from sheep affected by spongiform encephalopathy, identified by post-mortem histology of brain tissues, have demonstrated the presence of the same electrochemical characteristics. The catabolite responsible for the electrochemical features described above, which has not yet been structurally identified, is not extracted by the organic solvents used for performing chromatographic analysis of catecholamines or indolic catabolites. In conclusion, in view of the relatively low cost of the equipment and execution, this method could be systematically used for rapid and cheap control of the effects of many drugs and for prediagnosis screening of several pathological conditions.

LA PROGRESSION DU VIRUS SCHMALLENBERG EN EUROPE: UNE NOUVELLE MALADIE D'ÉLEVAGE DES RUMINANTS

Les éleveurs et les vétérinaires de Rhénanie, du NordWestphalie et des Pays-Bas signalent, pendant l’été 2011, une nouvelle maladie survenant dans des élevages de bovins laitiers. Les symptômes observés (hyperthermie dépassant 40°C, diminution de la production laitière, diarrhée aqueuse et parfois avortement) ne durent que quelques jours et la guérison survient rapidement. Seules quelques séquelles sont signalées ultérieurement du fait de l’action tératogène de l’agent causal. Les examens de laboratoire effectués ne permettent pas de reconnaître l’agent causal d’une maladie émergente ou résurgente connue (pestivirose, herpèsvirose bovine de type 1, fièvre aphteuse, fièvre catarrhale ovine, maladie hémorragique épizootique, fièvre de la vallée du Rift...). La maladie est signalée pour la première fois le 15 novembre 2011 (ProMED du 15 novembre 2011).

ACTUALITÉS SUR LA PARATUBERCULOSE BOVINE

Ruminant paratuberculosis (Johne’s disease) is caused by Mycobacterium avium subsp. paratuberculosis (Map). It has been known for a long time, but it is still a problem for livestock farmers. This digestive disease associated with cachexia affects mainly domestic and wild adult ruminants. It has spread progressively to areas previously considered as disease-free, due to livestock trading. One of the main causes of infection is a contaminated environment due to fecal shedding by adult cows, particularly those with diarrhea or asymptomatic heavy shedders. Control measures must target these animals specifically, and continuous monitoring is required to detect newly infected individuals in the herd. This article looks at the survival of Map in the environment and the transmission factors, as well as the improvement of methods for the diagnosis and control of paratuberculosis. The hypothesis of a zoonotic risk linked to Map is also considered due to its presence in milk and meat.

Méthodes de diagnostic des « maladies à prions » chez l'homme et chez l'animal

The potential existence of clinically silent cases of bovine spongiform encephalopathy (BSE) among cattle, and of humans incubating the new variant Creutzfeldt-Jakob disease (nvCJD) is still a major public health concern. Therefore, the development of screening tests for transmissible subacute spongiform encephalopathies (TSSE) in man and animals remains a priority. In the first part of this paper, we review the main methods used to diagnose generally clinical TSSE, such as brain imaging, electroencephalogram (EEG) analysis, and cerebrospinal fluid (CSF) analysis. In the second part, we present the post-mortem tests used to confirm a TSSE diagnosis, such as inoculation to laboratory animals, histological examination, and identification of abnormal prion protein (PrPres) using biochemical methods. Finally, the third part presents so-called rapid tests (Prionics, Bio-rad, Enfer), validated by the European Commission (EC) for post-slaughter BSE diagnosis in cattle. Now used on a large scale in Europe, these tests have helped assess the extent of the epizooty and eliminate from the food chain animals presenting a risk for human consumption. Since 2002, they have been used for the post-slaughter diagnosis of scrapie in small ruminants. New tests have recently been evaluated by the EC, but it is too soon to predict their role in the field.

Les coronavirus, biologie cellulaire et moléculaire. Discussion

A consensus seems to have been reached on the pathogen responsible for SARS (Severe Acute Respiratory Syndrome) being a newly recognised coronavirus. To answer some of the questions raised by the emergence of this previously unknown pathogen, the author presents the classification and characteristics of coronaviruses: single positive RNA strand of approximately 30,000 bases (the largest known RNA genome), complexe mode of expression of the genetic information, yet simple organisation of the virions with only 4 structural proteins. Coronaviruses have a relatively small host spectrum and a narrow tissue tropism. They have a special affinity for epithelial cells in the respiratory and digestive tracts. The author presents data on the mechanisms of this tissue specificity, using as an example group 1 coronaviruses, which include the transmissible gastroenteritis virus (TGEV). These viruses use aminopeptidase N as their receptor to break into the target cells. This molecule, expressed at the surface of epithelial cells, is recognised by the virus spike proteins. Receptor recognition is a major determinant of the species specificity in these viruses. This is why none of the group 1 animal coronaviruses is able to infect human cells, whose aminopeptidase N they do not recognise. The author describes the way the TGEV coronavirus has muted into the Porcine Respiratory Coronavirus (PRCV), responsible for a new respiratory infection which spread explosively in swine populations. The deletion of approximately 250 amino acids in the N-terminal region of the spike protein may be associated with the reduced virulence and switch of tissue tropism. Coronavirus infections induce early on a marked synthesis of interferon alpha. The identified induction mechanism partly differs from the mechanism generally described in RNA viruses, as it is essentially independent from viral replication, and involves the glycosylated M protein associated to the virions. The genome mutation rate in coronaviruses is relatively high, as expected with RNA viruses. And yet, the genetic drift associated with the SARS virus is the same as in the TGEV. Coronaviruses are also specialists in intergenomic recombination, a characteristic which could allow them to reconstitute viable genomes from altered ones. However, the SARS virus does not appear to originate from a recent recombination between a human virus and one of the currently identified animal coronavirus. To which of three known groups of coronaviruses does the SARS virus belong? The comparison of the complete genome sequence of the SARS virus, now known, with that of the other coronaviruses shows that its position is somewhere between the avian coronavirus group (e.g. Infectious Bronchitis Virus or IBV), and group 2 coronaviruses which affect mammals (e.g. bovine coronavirus). The author also points out that the organisation of the SARS virus genome (including the distribution of so-called “accessory” genes) shows intriguing similarities with that of the avian coronavirus group. All these characteristics would justify putting this new coronavirus in the group of its own, distinct from the existing ones.