Superdispersion in homogeneous unsaturated porous media using NMR propagators

The NMR propagator technique allows the measurements of the variance σ(2)=<(ξ-<ξ>)(2)> of the displacements as a function of time t when flowing in a porous media. The time dependence of σ is a very sensitive test of Gaussian behavior compared to the analysis of the shape of the propagators. Superdispersion occurs when σ(2)[proportionality]t(α) with the exponent α larger than 1. In a homogeneous 30-μm grain pack and 10 < Pe < 35, we observed weak superdispersion in saturated conditions (α = 1.17) and gradually strong superdispersion as the water saturation decreases (up to α = 1.5) during steady-state oil-water two-phase flow. In saturated conditions, the corresponding longitudinal propagators and breakthrough curves are Gaussian or nearly Gaussian, whereas in two-phase conditions, the longitudinal propagators are nonsymmetric and the breakthrough curves show a tail at long times.

Longitudinal follow-up of vision in a neuromyelitis optica cohort

BACKGROUND

Neuromyelitis optica (NMO) is an inflammatory disease associated with optic neuritis and myelitis. Recently, several studies showed that optical coherence tomography (OCT) could be an interesting method for the evaluation of disease severity; however, to date there are no studies with a longitudinal follow-up of visual function in NMO. The aim of this study was to assess the ability of OCT to evaluate the progression of visual dysfunction in NMO.

PATIENTS AND METHODS

A group of 30 NMO patients (thus, 60 eyes), comprised of 20 women and 10 men with a mean age of 43.7 +/- 12.3 years, were prospectively evaluated clinically and by a whole neuro-ophthalmological work-up, including: visual acuity (VA), fundoscopy, visual evoked potential (VEP), visual field (VF) and optical coherence tomography (OCT). All patients were tested at baseline (after a mean disease duration of 6.1 years) and after a mean time of follow-up of 18 months (range: 12-36 months).

RESULTS

Mean VA was similar at the two evaluation times (0.77 +/- 0.36 versus 0.77 +/- 0.35). The mean VF defect decreased slightly, but the difference was not significant (-5.9 +/- 1.3 dB versus -5.3 +/- 1.3 dB). In contrast, the mean retinal thickness seen on OCT decreased from 87.4 +/- 23.3 µm to 79.7 +/- 22.4 µm (p = 0.006). These modifications were only observed in eyes with a past or a recent history of optic neuritis (-15.1 µm; p < 0.001) and not in eyes without any history of optic neuritis (-2.4 µm; not significant). Also, they occurred independently of the occurrence of relapses (n = 13) and especially optic neuritis episodes; however, the number of optic neuritis episodes was low (n = 5).

CONCLUSION

OCT seems to be a more sensitive test than VA or VF for monitoring ophthalmological function in NMO and it seems to be helpful for the detection of infra-clinical episodes in patients with a past history of optic neuritis. Our results suggest that this easily performed technique should be used in the follow-up of NMO, but complementary studies are warranted to confirm its interest at an individual level.

[Optic neuropathy and meningioma: a diagnostic trap]

INTRODUCTION

Meningiomas are benign primary meningeal tumors. Their diagnosis may be incidental or in response to a work-up for neurological or ophthalmological symptoms.

PATIENTS AND METHODS

The clinical course of five patients with ophthalmological symptoms leading to the diagnosis of meningioma is described.

RESULTS

The case reports consist of five women (48 to 54 years old - mean 52 years at the onset of symptoms), all suffering from a progressive unilateral decrease in visual acuity with a normal initial fundus examination and ipsilateral visual field changes. Ancillary testing, in particular MRI and CT-scans, had to be repeated to make the diagnosis of meningioma, which was delayed from 18 months to 4 years.

DISCUSSION

The clinical presentation of these five cases was that of a retrobulbar optic neuropathy, which biased the work-up towards an inflammatory disease of the central nervous system such as multiple sclerosis. However, the atypical character of the neuropathy, which did not respond to intravenous steroids, caused the diagnosis to be questioned and radiological examinations repeated. The iso-intense appearance of meningiomas on T1 MR imaging and only slightly hyperintense appearance on T2 may result in a diagnostic delay if the exam is not performed and interpreted by an experienced professional. Gadolinium contrast, fat suppression and centration on the anterior visual pathways are essential to a proper MRI examination.

CONCLUSION

When confronted with a progressive, painless optic neuropathy unresponsive to steroid treatment, the diagnosis of meningioma of the anterior visual pathways must be considered. This diagnosis is enabled by a targeted MRI of the anterior visual pathways.

White matter volume is decreased in the brain of patients with neuromyelitis optica

BACKGROUND

Neuromyelitis optica (NMO) is an inflammatory disease involving predominantly the spinal cord and optic nerves. Whether patients with NMO have a loss in white or grey matter (GM) volumes remains to be determined.

METHODS

Thirty patients with NMO, 30 healthy subjects matched for age and gender, 21 patients with multiple sclerosis (MS) and 20 patients with a clinically isolated syndrome (CIS) were studied. We applied a SIENAX post-treatment software. We compared white matter (WM) and GM volumes between groups and explored correlations of changes in NMO patients with age, gender, duration, disease severity, visual acuity and T2 hyperintensities. We also performed a voxel-based morphometry (VBM) analysis to identify the regions affected by loss of volume.

RESULTS

White matter volume was significantly reduced in patients with NMO (764.4 ± 58.3 cm(3) ) compared to healthy subjects (843.1 ± 49.3 cm(3) ) (P < 0.001), whereas no difference was observed for the GM. Patients with CIS also presented an elective atrophy of WM and MS an atrophy of both WM and GM. We did not find any predictive factors of brain atrophy. The decrease in WM volume in NMO was noted even in the absence of visible MRI hypersignals. The VBM analysis found a few regions of WM atrophy (corpus callosum and optic radiations, P < 0.005, uncorrected) and a few regions of GM atrophy (thalamus and prefrontal cortex, P < 0.001, uncorrected).

CONCLUSION

These results suggest a significant brain involvement in NMO, especially an involvement of WM which appears not to be limited to secondary degeneration after spinal cord and optic nerve damage.

Chemical contamination during the preparation of cytotoxics: validation protocol for operators in hospital pharmacies

BACKGROUND AND OBJECTIVES

The chemical contamination during the preparation of cytotoxics remains a serious problem in hospital pharmacies and the operators could contribute to this risk during their manipulations. A validation protocol was developed using a non-toxic, highly detectable tracer, quinine dihydrochloride.

METHOD

Further, a method for a high recovery extraction and quantification of this marker, and a protocol covering the critical operations of cytotoxic preparation, was developed and validated. Various devices were used to fill the syringes and perfusion bags. All the filled containers and used materials were collected at the end of the protocol and the tracer was extracted in water. The contaminated water was analyzed by fluorimetry. The number of spots on the working pads was counted under ultraviolet light. During a total of 28 sessions, the procedure was applied by 20 different operators.

RESULTS

The mean cumulated quantities of contamination were 6.2 µL (0.6-23.8) and >10 spots (0-20), which was considered as high. No correlation was observed between the contamination rate and the operator's experience.

CONCLUSION

This validation protocol facilitates controlling the operators' working 'cleanliness' and helps to improve the initial and continuing training. This simple test presents an effective answer for the important issue of the chemical safety of operators.

From computed microtomography images to resistivity index calculations of heterogeneous carbonates using a dual-porosity pore-network approach: influence of percolation on the electrical transport properties

Standard reservoir evaluations are based on Archie's law relating the average water saturation to the average electrical resistivity by R(ind) = S(w)(-2). However, especially in the case of complex heterogeneous carbonates, deviation from Archie's law is observed and generally attributed to factors affecting the percolation or disconnectedness of the different phases (wetting films, microporosity, macropores) assuring electrical conductance. Pore-network models (PNM's) in combination with high-resolution computed microtomography (μ-CT) constitute a very effective tool to investigate the influence of the geometry and topology of the porous media on the spatial distribution of the conductive phase, and therefore on the shape of the resistivity index curve. An extended version of the classical PNM applicable to dual-porosity systems is presented. It combines the classical pore-network modeling applied on the macroporous space with the macroscopic properties of the microporous phase, supposing that the two pore systems act in parallel. Three-dimensional images provide information on the connectedness of the microporous phase, which is then included in the simulations. Electrical behavior of sandstone and two carbonates presenting distinct resistivity index curves were simulated and compared to measurements. Both Archie and "non-Archie" behavior were correctly reproduced, and the curve shape was explained considering percolation of the different phases.

High-risk syndrome for neuromyelitis optica: a descriptive and comparative study

Background: Neuromyelitis optica (NMO) frequently begins with a monofocal episode of optic neuritis or myelitis. A concept named high-risk syndrome (HRS) for NMO has been proposed for patients with monofocal episodes and NMO-IgG antibodies.

Objective: To describe HRS patients and compare them with NMO patients.

Methods: We identified 30 patients with HRS: 18 with extensive myelitis (HRM) and 12 with optic neuritis (HRON), in a database pooling patients from 25 centres in France. Clinical, laboratory/magnetic resonance imaging (MRI) data and outcome were analysed and compared with a national cohort of 125 NMO patients extracted from the same database.

Results: Mean follow-up was 4.8 years. Mean age at onset was 42.8 years (range: 12.4–70) with a female:male ratio of 0.9. Asymptomatic lesions were report on visual evoked potentials in 4/8 tested HRM patients and on spinal cord MRI in 2/7 HRON patients. Three patients died, two owing to a cervical lesion. HRS and NMO patients had similar clinical/paraclinical data, except for a predominance of men in the HRS group and a later mean age at onset in the HRM subgroup.

Conclusion: The description of HRS patients is compatible with a monofocal form of NMO. Asymptomatic lesions could be included in a new set of NMO diagnostic criteria.

Evaluation of health-related quality of life, fatigue and depression in neuromyelitis optica

BACKGROUND

The burden of multiple sclerosis (MS) includes fatigue, depression and worsening of health-related quality of life (HRQOL). These changes have not been yet measured in neuromyelitis optica (NMO). Our aim was to assess the HRQOL, fatigue and depression in NMO.

METHODS

We administered French validated self-questionnaires on HRQOL (SEP-59), fatigue (EMIF-SEP) and depression (EHD) to 40 patients followed up in two centres. We assessed the relationship of these parameters with gender, age, disability, disease duration, visual acuity and NMO-antibody status and also compared our results with equivalent data in MS and normal subjects derived from previous studies.

RESULTS

Health-related quality of life scores were lower (P < 0.01) in patients with NMO when compared to normal subjects. No significant difference was noted between patients with NMO and MS for most scores, the exceptions being HRQOL related to cognitive function (better in NMO than in MS), HRQOL related to sphincter dysfunction (worse in NMO than in MS) and the psychological dimension of fatigue (milder in NMO than in MS). Disability was the main predictive factor of an unfavourable evolution.

DISCUSSION

This study reveals the strong impact of NMO on HRQOL, fatigue and depression and the importance of screening patients, especially the more disabled, so as to initiate suitable treatment.

Long-term follow-up of neuromyelitis optica with a pediatric onset

BACKGROUND

Neuromyelitis optica (NMO) is a rare inflammatory disease. Average age at onset is 35 years. Few data exist on patients with pediatric-onset NMO (p-NMO), with disease onset before age 18 years. We report the clinical and paraclinical features and long-term outcome of patients with p-NMO and compare them with a large adult-onset NMO (a-NMO) cohort.

METHODS

We performed a retrospective, multicenter study of patients with p-NMO in pediatric and adult medical centers. We identified 125 patients with NMO (12 p-NMO; 113 a-NMO) fulfilling the 2006 criteria. Data were collected using hospital files and standardized assessment forms for NMO.

RESULTS

Patients with p-NMO were followed up during a mean 19.3 years. Median age at onset was 14.5 years (4.1-17.9) with a female:male ratio of 3:1. Three patients (25%) fulfilled Paty criteria for multiple sclerosis on first brain MRI, including one patient with acute disseminated encephalomyelitis. Median interval between onset and residual Expanded Disability Status Scale (EDSS) score 4 was 20.7 years, score 6 was 26 years, and score 7 was 28.7 years. Median interval between onset and residual visual loss ≤1/10 was 1.3 years. Compared with a-NMO, p-NMO showed a longer time to EDSS scores 4 and 6, largely explained by the severity of the first myelitis in the a-NMO group. Time to first treatment was longer in the p-NMO group (13.1 vs 3.4 years).

CONCLUSION

Patients with p-NMO can present a diffuse inflammatory process on first brain MRI and have a longer time to disability than patients with a-NMO.

Neuromyelitis optica in France: a multicenter study of 125 patients

BACKGROUND

There have been few epidemiologic studies on neuromyelitis optica (NMO) and none used the recent 2006 diagnostic criteria. Here we describe the clinical, laboratory, MRI, and disability course of NMO in a French cohort of 125 patients.

METHODS

We performed an observational, retrospective, multicenter study. Data were collected from September 2007 through August 2008, corresponding to the endpoint of the study. We identified 125 patients fulfilling the 2006 NMO criteria. Selection was made using hospital files and a specific clinical questionnaire for NMO.

RESULTS

Mean age at onset was 34.5 years (range 4-66) with a mean disease duration of 10 +/- 7.8 years at the endpoint. The patients were mainly (87%) Caucasian, with a female:male ratio of 3:1. In 90% of cases, the association of optic neuritis, longitudinal extensive myelitis, and a Paty-negative initial brain MRI was sufficient to fulfill the supportive criteria. Eighty-eight percent of patients were treated with immunosuppressive therapies. Median delay from onset to Expanded Disability Status Scale (EDSS) score 4 was 7 years; score 6, 10 years; and score 7, 21 years. The first episode of myelitis was immediately followed by an EDSS score > or = 4 in 37.3% of cases, and a severe residual visual loss was observed in 22% of patients after the first episode of optic neuritis. Multivariate analysis did not reveal any predictors of a poor evolution other than a high number of MRI brain lesions at diagnosis, which were predictive of a residual visual acuity < or = 1/10.

CONCLUSIONS

Our demographic data provide new data on disability in patients with neuromyelitis optica, most of whom were receiving treatment.

Ataxia with oculomotor apraxia type 2: clinical, biological and genotype/phenotype correlation study of a cohort of 90 patients

Ataxia with oculomotor apraxia type 2 (AOA2) is an autosomal recessive disease due to mutations in the senataxin gene, causing progressive cerebellar ataxia with peripheral neuropathy, cerebellar atrophy, occasional oculomotor apraxia and elevated alpha-feto-protein (AFP) serum level. We compiled a series of 67 previously reported and 58 novel ataxic patients who underwent senataxin gene sequencing because of suspected AOA2. An AOA2 diagnosis was established for 90 patients, originating from 15 countries worldwide, and 25 new senataxin gene mutations were found. In patients with AOA2, median AFP serum level was 31.0 microg/l at diagnosis, which was higher than the median AFP level of AOA2 negative patients: 13.8 microg/l, P = 0.0004; itself higher than the normal level (3.4 microg/l, range from 0.5 to 17.2 microg/l) because elevated AFP was one of the possible selection criteria. Polyneuropathy was found in 97.5% of AOA2 patients, cerebellar atrophy in 96%, occasional oculomotor apraxia in 51%, pyramidal signs in 20.5%, head tremor in 14%, dystonia in 13.5%, strabismus in 12.3% and chorea in 9.5%. No patient was lacking both peripheral neuropathy and cerebellar atrophy. The age at onset and presence of occasional oculomotor apraxia were negatively correlated to the progression rate of the disease (P = 0.03 and P = 0.009, respectively), whereas strabismus was positively correlated to the progression rate (P = 0.03). An increased AFP level as well as cerebellar atrophy seem to be stable in the course of the disease and to occur mostly at or before the onset of the disease. One of the two patients with a normal AFP level at diagnosis had high AFP levels 4 years later, while the other had borderline levels. The probability of missing AOA2 diagnosis, in case of sequencing senataxin gene only in non-Friedreich ataxia non-ataxia-telangiectasia ataxic patients with AFP level > or =7 microg/l, is 0.23% and the probability for a non-Friedreich ataxia non-ataxia-telangiectasia ataxic patient to be affected with AOA2 with AFP levels > or =7 microg/l is 46%. Therefore, selection of patients with an AFP level above 7 microg/l for senataxin gene sequencing is a good strategy for AOA2 diagnosis. Pyramidal signs and dystonia were more frequent and disease was less severe with missense mutations in the helicase domain of senataxin gene than with missense mutations out of helicase domain and deletion and nonsense mutations (P = 0.001, P = 0.008 and P = 0.01, respectively). The lack of pyramidal signs in most patients may be explained by masking due to severe motor neuropathy.

Epidemiological, clinical, paraclinical and molecular study of a cohort of 102 patients affected with autosomal recessive progressive cerebellar ataxia from Alsace, Eastern France: implications for clinical management

While Friedreich's ataxia (FRDA) and ataxia telangiectasia (AT) are known to be the two most frequent forms of autosomal recessive cerebellar ataxia (ARCA), knowledge on the other forms of ARCA has been obtained only recently, and they appear to be rarer. Little is known about the epidemiological features and the relative frequency of the ARCAs and only few data are available about the comparative features of ARCAs. We prospectively studied 102 suspected ARCA cases from Eastern France (including 95 from the Alsace region) between 2002 and 2008. The diagnostic procedure was based on a sequential strategic scheme. We examined the clinical, paraclinical and molecular features of the large cohort of patients and compared features and epidemiology according to molecular diagnosis. A molecular diagnosis could be established for 57 patients; 36 were affected with FRDA, seven with ataxia plus oculomotor apraxia type 2 (AOA2), four with AT, three with ataxia plus oculomotor apraxia type 1 (AOA1), three with Marinesco-Sjögren syndrome, two with autosomal recessive spastic ataxia of Charlevoix-Saguenay (ARSACS), one with ataxia with vitamin E deficiency (AVED) and one with autosomal recessive cerebellar ataxia type 2 (ARCA2). The group of patients with no identified mutation had a significantly lower spinocerebellar degeneration functional score corrected for disease duration (SDFS/DD ratio; p = 0.002) and comprised a significantly higher proportion of cases with onset after 20 years (p < 0.01). Extensor plantar reflexes were rarer and cerebellar atrophy was more frequent in the group of patients with a known non-Friedreich ARCA compared to all other patients (p < 0.0001 and p = 0.0003, respectively). Lower limb areflexia and electroneuromyographic evidences of peripheral neuropathy were more frequent in the Friedreich ataxia group than in the group with a known non-Friedreich ataxia and were more frequent in the later group than in the group with no identified mutation (p = 0.0001 and p = 0.01, respectively). The overall prevalence of ARCA in Alsace is 1/19,000. We can infer the prevalence of FRDA in Alsace to be 1/50,000 and infer that AT is approximately eight times less frequent than FRDA. MSS, AOA2 and ARSACS appear only slightly less frequent than AT. Despite the broad variability of severity, Friedreich ataxia patients are clinically distinct from the other forms of ARCA. Patients with no identified mutation have more often a pure cerebellar degenerative disease or a spastic ataxia phenotype. It appears that ARCA cases can be divided into two major groups of different prognosis, an early-onset group with a highly probable genetic cause and an adult-onset group with better prognosis for which a genetic cause is more difficult to prove but not excluded. ARCAs are rare, early-disabling and genetically heterogeneous diseases dominated by FRDA. Several of the recently identified ARCAs, such as AVED, ARSACS, AOA1, AOA2 and MSS, have a prevalence close to AT and should be searched for extensively irrespective of ethnic origins. The strategic scheme is a useful tool for the diagnosis of ARCAs in clinical practice.

Is neuromyelitis optica associated with human leukocyte antigen?

BACKGROUND

To establish whether or not multiple sclerosis (MS) and neuromyelitis optica (NMO) are different pathological entities, we wondered whether MS patients and NMO patients share the same pattern of human leukocyte antigen (HLA) predisposition.

OBJECTIVE

To study a putative association between susceptibility to NMO and HLA class I or class II loci in Caucasians.

METHODS

A total of 39 unrelated Caucasian patients with NMO and six patients at a high risk of converting to NMO were studied. DNA genotyping of HLA class I and class II loci was assessed and allelic frequencies were reported at a high-resolution level. A case-control study by comparing the allelic distribution in the NMO patients with that of a French Caucasian MS group and a French Caucasian healthy group was carried out.

RESULTS

The frequencies of HLA-DQA1, DQB1, and HLA-DRB1 DR2 alleles in the NMO group were intermediate between the healthy control group and the MS group. The DPB1*0501 allele was not increased in the NMO group compared with the healthy control group. The distribution of HLA-DRB1 allele enabled to distinguish between NMO-IgG-positive patients and healthy controls (P = 0.01). NMO-IgG-negative patients presented an HLA II pattern closer to that of the MS group (P = 0.01).

CONCLUSION

In contrast to the reported results in Asian opticospinal MS, we found no association between the DPB1*0501 allele and NMO in our Caucasian patients. Moreover, we suggest that NMO-IgG-positive patients could represent a distinct NMO group in terms of their genetic susceptibility.