Interêt de la corticothérapie dans le traitement de la douleur à la phase aiguë du syndrome de Guillain-Barré

INTRODUCTION

Pain is a common problem in both adults and children with Guillain-Barré Syndrome (GBS). Corticosteroids are rarely used in the treatment of pain in the course of GBS, although some authors have pointed out their value for the treatment of neuropathic pain. We report four patients with GBS whose pain was rapidly relieved by administration of corticosteroids.

METHODS

We reviewed retrospectively a series of four patients with GBS seen from September 2001 to February 2003. All patients had plexual (Case 3), trunkular (case 1), radicular (case 2) or focal (case 4) pain. Pain was treated with corticosteroids via oral (cases 1 and 2) or intravenous routes (cases 3 and 4). Corticoids where used after failure of other analgesic agents.

RESULTS

Pain relief was obtained after the first administration and persisted even after tapering off steroid treatment. No particular complication was observed during treatment course.

CONCLUSION

Our experience suggests that controlled studies should be set up to evaluate the place of corticosteroid treatment for the management of pain in patients with GBS.

[Review of nutritional and respiratory support in ALS]

During the evolution of amyotrophic lateral sclerosis (ALS), quality of life and survival of patients are related to respiratory and nutritional status. After diagnosis, a multidisciplinary care has to be promptly organized and coordinated by the referring neurologist. The nutritional and respiratory support imply that neurologists know their specific means of evaluation with their sensitivity and sensibility and be able to recognize clinical risk situations. The informations of patients on assisted-ventilation and nutritional support by using gastrostomy may be done early, precisely and trustfully. Well informed patient's choices must be respected. Nutritional and respiratory supports may be based on recommendations established by the American Academy of Neurology. This review will present and discuss their main aspects in patients with ALS.

Atypical electrophysiologic findings in chronic inflammatory demyelinating polyneuropathy (CIDP) – diagnosis confirmed by nerve biopsy

OBJECTIVES

Numerous sets of electrophysiological criteria of chronic inflammatory demyelinating polyneuropathy (CIDP) have been proposed, among which the criteria established by an ad hoc subcommittee of the American Academy of Neurology (AAN) in 1991 (Neurology 41 (1991) 617) are the most widely used. As they seemed rather restrictive, the Inflammatory Neuropathy Cause and Treatment (INCAT) group (Ann. Neurol. 50 (2001) 195) proposed modifications of these electrophysiological criteria. However, even using these criteria, some cases of CIDP may not be recognized. In such cases, nerve biopsy has proven useful for confirmation of the diagnosis by demonstrating specific abnormalities. The objective of the study was to determine the profile of electrophysiological abnormalities in patients with atypical electrophysiologic criteria of CIDP and the diagnostic value of multiple A waves and a low median to sural amplitude ratio.

PATIENTS AND METHODS

Over a period of 3 years, we classified 44 patients into two categories: those presenting the strict AAN and/or INCAT criteria and those who we regarded as cases of CIDP not meeting these criteria. All patients benefited from one or more clinical and electrophysiological examination. Extensive biological workup and genetic study when appropriate excluded other causes of neuropathy. Nerve biopsies were taken from all patients and samples were included in paraffin and epon for systematic light, teasing and electron microscopic examination.

RESULTS AND CONCLUSION

Out of 44 patients, 36 fulfilled the INCAT or AAN criteria. In eight other patients, the diagnosis of CIDP was suspected on clinical and EMG examinations and confirmed by nerve biopsy. In these cases, the electrophysiological exploration showed some abnormalities such as multiple A waves in four out of eight patients or an abnormal pattern of the sensory responses of the median and sural nerves in four out of eight patients that were more indicative of an initial demyelinating process. Six of our patients received immunomodulatory treatment, and five responded favorably.

Influenza vaccine technologies and the use of the cell-culture process (cell-culture influenza vaccine)

Influenza vaccines have been produced for decades in eggs by a classical technology. A range of new vaccine technologies and approaches has been applied to improving these vaccines. Foremost among these are the use of mammalian cells to produce influenza viruses, the use of new adjuvants, and a live attenuated vaccine. Mammalian cell-derived vaccines, produced in nontumorigenic cell lines, have been developed and shown to be effective production systems as alternatives to eggs. This manuscript discusses the advantages and challenges of mammalian cell production, as well as alternative technologies for influenza vaccines.

Presence of the LEE (locus of enterocyte effacement) in pig attaching and effacing Escherichia coli and characterization of eae, espA, espB and espD genes of PEPEC (pig EPEC) strain 1390

In the present study, attaching and effacing Escherichia coli (AEEC) O45 isolates from post-weaning pigs with diarrhoea were examined for the presence of the LEE (locus of enterocyte effacement) using various DNA probes derived from the LEE of human enteropathogenic E. coli (EPEC) strain E2348/69. The LEE fragment was conserved among the eae -positive pig isolates. The attaching and effacing activity of PEPEC (pig EPEC) O45 isolates is highly correlated with the presence of the LEE. Nevertheless, for some PEPEC isolates, the insertion site of the LEE is different or has diverged during evolution. The presence of the LEE fragment in PEPEC isolates provides further evidence that the LEE region is conserved among AEEC of different animal origins. In addition, the nucleotide sequence of the region containing the eae gene and esp genes of a pig AEEC isolate, strain 1390, was determined. Among examined Eae proteins, Eae of strain 1390 showed the highest similarity with Eae belonging to the beta intimin group such as the Eae of rabbit AEEC. Moreover, all pig strains that produced attaching and effacing lesions in piglets and pig ileal explants belonged to the beta intimin group. The deduced amino acid sequences of the EspA, EspB and EspD proteins of strain 1390 showed particularly strong homology to those of AEEC strains presenting a beta intimin allele. Thus, pig AEEC possess the LEE sequences, and for the strain 1390, sequences of the eae and esp regions are related to those of other AEEC, in particular, strains presenting a beta intimin allele, such as the rabbit AEEC.

A Phase I, randomized controlled clinical trial to study the reactogenicity and immunogenicity of a new split influenza vaccine derived from a non-tumorigenic cell line

We have found that our MDCK-derived cell line (BV-5F1) is non-tumorigenic in tests conducted in accordance with FDA guidelines, and thus may be suitable for producing live, attenuated or inactivated vaccine. The cell line has been extensively tested for the presence of contaminating microorganisms. No infectious agents of viral or other microbial origin were present. Using the BV-5F1 cell line, we have now designed a process for the large-scale production of influenza virus for the manufacture of a vaccine. The production system involves expansion of cells anchored on a microcarrier using stirred fermenters, followed by virus infection. Viral particles are purified in a way similar to the licensed egg-derived vaccine Fluviral SF and mainly involves ultracentrifugation, ultrafiltration and formaldehyde inactivation. The final product is a split inactivated vaccine. A randomized, double-blind clinical study was made in healthy adults using the new split influenza vaccine derived from viruses grown in cell culture (bivalent formulation). The results of this Phase I study have demonstrated that the split influenza vaccine derived from cell culture is highly immunogenic and safe in adults.

Characterization of the thermosensitive ts453 reovirus mutant: increased dsRNA binding of sigma 3 protein correlates with interferon resistance

The mutation harbored by the reovirus ts453 thermosensitive mutant has been assigned to the S4 gene encoding the major outer capsid protein sigma 3. Previous gene sequencing has identified a nonconservative amino acid substitution located near the zinc finger of sigma 3 protein in the mutant. Coexpression in COS cells of the sigma 3 protein presenting this amino acid substitution (N16K), together with the other major capsid protein mu 1, has also revealed an altered interaction between the two proteins; this altered interaction prevents the sigma 3-dependent cleavage of mu 1 to mu 1C. This could explain the lack of outer capsid assembly observed during ts453 virus infection at nonpermissive temperature. In the present study, we pursued the characterization of this mutant sigma 3 protein. Although the N16K mutation is located close to the zinc finger region, it did not affect the ability of the protein to bind zinc. In contrast, this mutation, as well as mutations within the zinc finger motif itself, can increase the binding of the protein to double-stranded RNA (dsRNA). It also appears that the N16K mutant protein is more efficiently transported to the nucleus than the wild-type protein, an observation consistent with the postulated role of dsRNA binding in sigma 3 nuclear presence. The lack of association with mu 1, and/or the increased dsRNA-binding activity of sigma 3, could be responsible for a partial resistance of the ts453 virus to interferon treatment and this could have important consequences in the context of protein synthesis regulation during natural reovirus infection.

Interferon has no protective effect during acute or persistent reovirus infection of mouse SC1 fibroblasts

Mouse SC1 fibroblasts can support reovirus multiplication although they exhibit a partial resistance to viral-induced cytopathology; a significant percentage of infected SC1 cells can remain viable while becoming persistently infected by the virus. In the present study, the possible role of interferon on the fate of reovirus-infected cells was investigated. Treatment of mouse L fibroblasts with beta-interferon resulted in a reduced viral efficiency of plating while essentially no effect was observed on SC1 cells; the results were similar with the unrelated encephalomyocarditis virus. This suggests that the interferon-regulated pathways are somehow deficient in SC1 cells even though these cells do respond to interferon treatment, as evidenced by an increase in the level of active interferon-inducible protein kinase double-stranded RNA-dependent (PKR) enzyme. Persistently infected SC1 cells constitutively release interferon even though treatment with anti-interferon antiserum suggests that interferon presence is unrelated to maintenance of the persistent state. The possible significance of the correlation between the lack of interferon-induced antiviral effect and relative resistance of SC1 cells to viral-induced cytopathology is briefly discussed.

Site-directed mutagenesis of the double-stranded RNA binding domain of bacterially-expressed sigma 3 reovirus protein

The affinity of the reovirus sigma 3 protein for double-stranded RNA (dsRNA) is well established, and efforts have been made to identify the amino acids involved in this property. In the present study, we further examined the importance of two basic amino acids motifs, located in the carboxy-terminal third of the protein. Mutants, previously characterized in COS cells, were expressed in bacterial cells using the pET expression system. The capability of the different mutants to interact with dsRNA was then determined by the binding of radiolabeled dsRNA to proteins resolved by SDS-polyacrylamide gel electrophoresis and transferred to nitrocellulose filters. It appears that the most carboxy-terminal motif is absolutely required for the binding but the second motif also contributes to this property. However, only the carboxy-terminal motif is required for normal binding upon removal of the amino-terminal domain of the protein by proteolytic cleavage, a procedure previously shown to increase dsRNA-binding. The basic charges in both motifs are important, while breaking of their potential to adopt an alpha helical configuration does not affect binding efficiency. Furthermore, alanine substitution of a single basic amino acid in the carboxy-terminal motif can be sufficient to strongly reduce the binding of dsRNA to the protein. Altogether, these data suggest that basic amino acids of the sigma 3 carboxy-terminal motif are directly involved in dsRNA binding, while the other basic motif may contribute by preventing an inhibitory effect of the amino-terminal portion of the protein.

Two basic motifs of reovirus sigma 3 protein are involved in double-stranded RNA binding

It has been reported that the sigma 3 protein of reovirus can exert an inhibitory effect on the cellular double-stranded RNA (dsRNA) activated protein kinase. Activation of this kinase is thought to be a general mechanism mediating a cellular antiviral response. This enzyme can also be activated upon transfection, resulting in translational inhibition of plasmid-encoded mRNAs. sigma 3 has an affinity for dsRNA postulated to be responsible for antikinase activity. In the present study, site-directed mutagenesis was performed on two basic regions previously suggested as dsRNA-binding motifs and the mutant sigma 3 proteins were then expressed in COS cells. These experiments revealed that both motifs are involved in sigma 3 attachment to RNA. Expression of the mutants lacking RNA-binding capability is stimulated by coexpression of another dsRNA-binding protein, the E3L vaccinia virus protein. These results support a model in which the attachment to dsRNA is directly responsible for the trans-stimulating effect of sigma 3 on expression of cotransfected genes.

The sequence similarity of reovirus sigma 3 protein to picornaviral proteases is unrelated to its role in mu 1 viral protein cleavage

Recent data have shown that the reovirus sigma 3 protein is the only viral product required for proteolytic conversion of the viral mu 1 protein to mu 1C. In an effort to determine the importance of a sigma 3 region exhibiting sequence similarity to a functionally important region of picornaviral proteases, we analyzed proteins produced in COS cells cotransfected with expression vectors encoding mu 1 and either wild-type or mutated forms of sigma 3. This approach revealed that association with sigma 3 contributes to the stability of mu 1-related polypeptides (mu 1 + mu 1C), but conservation of the sigma 3 region related to picornaviral proteases is not required for proteolytic conversion of mu 1 to mu 1C.

Mutations in a CCHC zinc-binding motif of the reovirus sigma 3 protein decrease its intracellular stability

It has been demonstrated that the sigma 3 protein of reovirus harbors a zinc-binding domain in its amino-terminal portion. A putative zinc finger in the CCHH form is located in this domain and was considered to be a good candidate for the zinc-binding motif. We performed site-directed mutagenesis to substitute amino acids in this region and demonstrated that many of these mutants, although expressed in COS cells, were unstable compared with the wild-type protein. Further analysis revealed that zinc-binding capability, as measured by retention on a zinc chelate affinity adsorbent, correlates with stability. These studies also allowed us to identify a CCHC box as the most probable zinc-binding motif.

Establishment of persistent reovirus infection in SC1 cells: absence of protein synthesis inhibition and increased level of double-stranded RNA-activated protein kinase

In the present study we report the establishment and characterization of an SC1 cell line persistently infected by reovirus. We observed that a significant percentage of SC1 cells was resistant to cell lysis upon infection with non-defective reovirus stocks. The apparent resistance of SC1 cells to the virus-induced inhibition of protein synthesis is probably an important factor favoring the establishment of such a persistence. The remaining cells, obtained following reovirus infection at a high multiplicity of infection, were kept as a continuous cell line and shown to have normal growth rate. They also released a high titer of virus that did not appear to differ from the original stock in neither infectivity nor genomic pattern. Electron microscopic examination further confirmed the presence of well-developed viral inclusions in the persistently infected cells. These cells were resistant to viral superinfection and exhibited a high constitutive level of the double-stranded RNA-activated protein kinase that might be involved in this resistance. We suggest that this cell line might be an interesting, and possibly more natural system than most previously used cell lines, for the continuing study of virus-host cell interactions during establishment of viral persistence using the much-studied model of reovirus infection.