Antiepileptic drugs modify power of high EEG frequencies and their neural generators

BACKGROUND

The clinical and molecular effects of antiepileptic drugs (AEDs) have been extensively investigated. Much less is known about their effects on human electrophysiology.

METHODS

Topographic analysis in the frequency domain has been used to analyze 104 electroencephalogram (EEG) epochs of 52 patients presenting with first-ever generalized seizure, with normal MRI and EEG. Patients were treated with valproate, arbamazepine, or lamotrigine in monotherapy (each group n = 13). Thirteen patients without medication served as a control group.

RESULTS

Carbamazepine and lamotrigine, both sodium-channel modulators, altered brain topography in the gamma range in the same frequency bands (50-60 Hz). Valproate, which has multiple actions on sodium and calcium channels as well as GABA turnover, modified brain topography in the low gamma range (30-40 Hz). No such changes were found in the control group. For all AEDs, the neural generators were shifted more anteriorly in medial temporal through to inferior frontal regions.

CONCLUSION

Decreased gamma-power and anterior shift of neural generators after AED introduction reflect AED influence on human electrophysiology.

[Aortic bioprosthesis implanted percutaneously: three year follow up]

Percutaneous implantation of a bioprosthesis for the treatment of degenerative aortic stenosis ushered in a new era for interventional cardiology, and now represents the best therapeutic option for a growing number of patients for whom surgical aortic replacement would be too risky. This is the case in about a third of symptomatic patients affected. Between 2003 and 2005, we performed initial feasibility studies (I-REVIVE and RECAST) in Rouen, on non-operable patients in a critical state, included for purely compassionate reasons. The valve used was a pericardial bioprosthesis mounted in an expandable balloon stent. The mean age of the patients was 80 years, all had multiple co-morbidity and had been turned down by the cardiac surgeons. In 33 of the 36 included patients, the technique was attempted by the anterograde trans-septal approach (n=27, success rate 80%) or by the retrograde arterial route (n=7, success rate 57%). Echocardiography following implantation revealed a final aortic surface area of 1.70 cm2 and a transvalvular gradient of 9 mmHg. A significant paravalvular aortic leak was noted in 5 cases. There were 6 deaths by 1 month, related to the procedure, and 10 deaths by 6 months, from non-cardiac causes and not related to the procedure. There was no occurrence of coronary occlusion, secondary displacement or dysfunction of the prosthesis. In December 2006, 8 patients reached 2 years of follow up, and two others reached 3 years, symptom free and still with an unchanged valvular function. Significant technological improvements have made the technique simpler, quicker and safer, with very much improved short and long term results. The new trans-apical approach is under evaluation with some promising initial results. More than 280 patients have been implanted to date. Other implantable prostheses are under evaluation. This therapeutic modality looks likely to develop rapidly, and in the near future it should offer a new and optimal solution for all high surgical risk or non-operable patients.

[Revascularisation of unprotected left main coronary artery disease: an update]

Coronary bypass grafting is the reference treatment of unprotected left main coronary disease. Nevertheless, the experience of invasive cardiologists and the introduction of active stents make angioplasty possible in selected cases. Only the results of controlled clinical trials (SYNTAX trial currently under way) will enable physicians to choose the most appropriate method of revascularisation for their patients.

A founder haplotype for autosomal dominant sensory ataxia in Eastern Canada

We present phenotypic and genotypic data for an additional family with autosomal dominant sensory ataxia, a disease characterized by gait difficulties associated with diminished sensation in the limbs and areflexia. The same disease haplotype spanning the entire SNAX1 locus is observed in affected members of this second family, enabling the locus to be reduced to a 7.3-cM interval.

Genetic susceptibility to MS: a second stage analysis in Canadian MS families

Four published genome screens have identified a number of markers with increased sharing in multiple sclerosis (MS) families, although none has reached statistical significance. One hundred and five markers previously identified as showing increased sharing in Canadian, British, Finnish, and American genome screens were genotyped in 219 sibling pairs ascertained from the database of the Canadian Collaborative Project on Genetic Susceptibility to MS (CCPGSMS). No markers examined met criteria for significant linkage. Markers located at 5p14 and 17q22 were analyzed in a total of 333 sibling pairs and attained mlod scores of 2.27 and 1.14, respectively. The known HLA Class II DRB1 association with MS was confirmed (P<0.0001). Significant transmission disequilibrium was also observed for D17S789 at 17q22 (P=0.0015). This study highlights the difficulty of searching for genes with only mild-to-moderate effects on susceptibility, although large effects of specific loci may still be present in individual families. Future progress in the genetics of this complex trait may be helped by (1) focussing on more ethnically homogeneous samples, (2) using an increased number of MS families, and (3) using transmission disequilibrium analysis in candidate regions rather than the affected relative pair linkage analysis.

Water and soil pollution in vineyards of central Thailand

Very intensive cultivation systems have been developed in the delta of the Chao Phraya River for about a century. The objective of the study was to determine the fate of the fertilisers and pesticides applied to vineyards grown on raised beds. Water samples were collected from the outlet of a vineyard to determine the discharge of pollutants in the canal. The accumulation of elements in the soil was investigated by analysing soil samples from different fields. Fertilisation was estimated at 670 kg N, 300 kg P, and 560 kg K year(-1) ha(-1). Insecticides and fungicides were applied every four days on average, using up to 23 different molecules. Little N and no P were discharged in the canals in solution and discharge in suspension was minor. Pesticides were detected in 36% of the water samples. The topsoil contained 1600 mg kg(-1) Bray II P, 936 mg kg(-1) exchangeable K, 170 mg kg(-1) total Cu, and 167 mg kg(-1) total Zn. Pesticides were detected in 62% of the fruits after peeling. Overuse of fertilisers did not lead to water pollution, but overuse of pesticides resulted in pollution of the water bodies and of the fruits. Most applied elements accumulated in the soil, resulting in high values of P, K, Cu, and Zn.

Electrical dose and seizure threshold: relations to clinical outcome and cognitive effects in bifrontal, bitemporal, and right unilateral ECT

In patients allocated blindly and randomly to receive bitemporal, right unilateral, or bifrontal electroconvulsive therapy, seizure length, electrophysiologic characteristics (dynamic impedance, seizure threshold, and changes in threshold), and the degree of suprathreshold stimulation were recorded. The relations of these variables to clinical outcome and cognitive effects were determined. There were no differences in seizure length between groups, and there were no significant correlations between seizure length and any measure of clinical response. There were substantial differences between the groups in mean charge per treatment, with the right unilateral group receiving lower doses than either bilateral group. Convulsion time was inversely related to applied charge and the rate of increase in charge. There were no significant correlations between impedance, charge, energy, or rate of increase in charge on the one hand, and clinical improvement on the other. The increase in threshold during the course of treatment was not related to clinical change. Cognitive impairment was related to electrical dose only in the bifrontal group, which showed the least degree of treatment-induced intellectual dysfunction. Compared with bitemporal or right unilateral treatment, bifrontal electroconvulsive therapy yields the best ratio of benefits to side effects and should be given at threshold level to minimize cognitive loss.

Clinical and electrophysiological study in French-Canadian population with Charcot-Marie-tooth disease type 1A associated with 17p11.2 duplication

BACKGROUND

The aim of the present study was to examine the frequency and the phenotypic manifestations in a French-Canadian population with a chromosome 17p11.2 duplication (Charcot-Marie-Tooth type 1A, CMT-1A).

METHODS

Molecular analysis were performed by Southern blot using pVAW409R3a probe. Clinical evaluation was carried out according to the scale defined by the European HMSN Consortium.

RESULTS

The frequency of duplication was found to be similar in the adult (70.8%) and pediatric (72.7%) populations. Onset of symptoms occurred before 20 years of age in 85.7% of adult cases and before the age of 5 in 80% of the pediatric cases. The classical CMT syndrome was observed in 77% of the cases and the syndrome was associated with additional features in 15% of cases in the adult population. All the children presented with classical CMT syndrome with no additional features. There was a significant correlation between the disability score and the duration of the disease but no correlation was found between median nerve conduction velocity and the functional handicap, the age at onset or the duration of the disease. In one family, there was a very conspicuous anticipation over five observed generations.

CONCLUSION

This study reveals that the age at onset, the clinical and electrophysiological variability as well as the functional disability variations in a French-Canadian population did not differ from those reported in other populations.

Autosomal recessive spastic ataxia of Charlevoix-Saguenay

A form of autosomal recessive spastic ataxia unique to the Charlevoix-Saguenay area was clinically identified 20 years ago in patients from that region. This region of Québec, Canada, was once considered a genetic isolate. First noted at gait initiation, signs of ataxia slowly progress along with spasticity of the four limbs, slurred speech, and followed by distal amyotrophy. Early diagnosis relies on the presence of prominent myelinated fibers embedding retinal blood vessels at funduscopy and marked saccadic alteration of ocular smooth pursuit. Imaging of the posterior fossa shows cerebellar vermis atrophy and nerve conduction studies reveal loss of sensory and reduced motor conduction velocities. The clinical features are consistent with a developmental defect in myelination of both retinal and peripheral nerve fibers. The cause of this defect and the progressive axonal degeneration in the corticospinal and spinocerebellar tracts, as well as in the peripheral nerves is still unknown. Results of recent molecular genetic linkage analysis have located the gene locus to chromosome 13q12. Further research is needed to define where this hereditary spastic ataxia stands in the classification of the early onset spinocerebellar degenerations.

Recent studies on oculopharyngeal muscular dystrophy in Québec

In 1990, we launched a major study to ascertain the clinical picture of OPMD in Québec and to identify large families for linkage analysis. In 14 patients, the chromosomes were karyotyped to eliminate any deletion or translocation. Relevant family information and clinical data were computerized and correlations were sought for the age of onset, the identification of the first symptom and the distribution of weakness. A simple test to detect dysphagia was validated. Twenty-one families have taken part in the study, which led to our localization of the gene in 1995 [Brais B, Xie Y-G, Sanson M, et al. Hum Mol Genet 1995; 4:429-434]. At least one case in each family underwent muscle biopsy to confirm the presence of the typical nuclear filaments found in OPMD. Electrodiagnostic and pathologic studies were also conducted to better understand the disease process. An illustrative case is presented.

A full genome search in multiple sclerosis

The aetiology of multiple sclerosis (MS) is uncertain. There is strong circumstantial evidence to indicate it is an autoimmune complex trait. Risks for first degree relatives are increased some 20 fold over the general population. Twin studies have shown monozygotic concordance rates of 25-30% compared to 4% for dizygotic twins and siblings. Studies of adoptees and half sibs show that familial risk is determined by genes, but environmental factors strongly influence observed geographic differences. Studies of candidate genes have been largely unrewarding. We report a genome search using 257 microsatellite markers with average spacing of 15.2 cM in 100 sibling pairs (Table 1, data set 1 - DS1). A locus of lambda>3 was excluded from 88% of the genome. Five loci with maximum lod scores (MLS) of >1 were identified on chromosomes 2, 3, 5, 11 and X. Two additional data sets containing 44 (Table 1, DS2) and 78 sib pairs (Table 1, DS3) respectively, were used to further evaluate the HLA region on 6p21 and a locus on chromosome 5 with an MLS of 4.24. Markers within 6p21 gave MLS of 0.65 (non-significant, NS). However, D6S461, just outside the HLA region, showed significant evidence for linkage disequilibrium by the transmission disequilibrium test (TDT), in all three data sets (for DS1 chi2 = 10.8, adjusted P < 0.01)(DS2 and DS3 chi2 = 10.9, P < 0.0005), suggesting a modest susceptibility locus in this region. On chromosome 5p results from all three data sets (222 sib pairs) yielded a multipoint MLS of 1.6. The results support genetic epidemiological evidence that several genes interact epistatically to determine heritable susceptibility.

New direct assay of free protein S antigen applied to diagnosis of protein S deficiency

Congenital deficiencies of protein S (PS) are associated with thrombophilia. Their characterization and classification have been hampered by the complex physiology of the protein C-protein S system and the poor standardization and reliability of laboratory assays. The free active form of protein S is usually determined by immunoassay using polyclonal antibodies in the plasma supernate after polyethyleneglycol (PEG) precipitation. A new one step ELISA using two monoclonal antibodies specific for distinct epitopes of the free form of protein S has been developed for the direct measurement of free PS in untreated plasma. We have tested two ELISA assays for free PS. One assay was based on the PEG precipitation (Asserachrom PS, Stago, Asnières, France) whereas the other was a one step ELISA assay (Asserachrom free PS, Stago). Values were obtained in 35 PS deficient patients recruited among 500 consecutive patients evaluated by the laboratory for diagnosis of congenital disorders of coagulation. Values were compared to those obtained in 50 patients with no PS deficiency matched for age and sex with the PS deficient patients as well as in 33 normal subjects and in 12 pregnant women. Strong correlation was found between the two tests (r = 0.81, p < 10(-5)) in the entire population (n = 130), as well as in the separate groups. The new one step ELISA was more accurate than the PEG free PS determination. Determination of PS activity and antigens allowed us to separate quantitative and qualitative deficiencies. Among the qualitative deficiencies, isolated decrease in PS activity was the most frequent defect observed (66%). This fact questions the substitution of PS activity assays by the one step antigenic free PS ELISA assay.