Evaluation of semi-automatic image analysis tools for cerebrospinal fluid electrophoresis of IgG oligoclonal bands.

BACKGROUND: IgG concentrations in cerebrospinal fluid generally range from 20 to 45 mg/L. In multiple sclerosis immune reactions lead to intrathecal synthesis of specific IgGs that can be detected in biological fluid samples both quantitatively and qualitatively by isoelectric focusing of supplementary oligoclonal IgG bands. METHOD: A simple tool, using the MATLAB application, to facilitate and improve isoelectric focusing profile analysis is presented and evaluated in terms of its sensitivity, repeatability and reproducibility. A comparison between human readers and semi-automatic method has also been performed. RESULTS: Results from the semi-automatic method were found to be equivalent or superior to generally employed laboratory methods. Repeatability analysis for semi-automatic processing yielded coefficients of variation (CVs) in the 3-7% range, and using a sample with an estimated IgG concentration of 200 mg/L, four bands were still visible after dilution to 5 mg/L, corresponding to band concentrations of 1.1-1.6 mg/L. Discordances between visual inspection and automatic analysis only appear at threshold levels for interpretation (the gray zone). CONCLUSION: The semi-automatic method has acceptable performance for routine implementation.

Semi-automated image analysis of gel electrophoresis of cerebrospinal fluid for oligoclonal band detection.

Detection of oligoclonal electrophoretic bands in cerebrospinal fluid (CSF) is an important diagnostic tool for Multiple Sclerosis (MS). Electrophoretic profiles are difficult to interpret due to low contrast and artefacts. A semi-automated method to ease analysis and to reduce subjectivity is presented. The method sequentially converts color images to grayscale, realigns bands, removes artifacts, then converts 2D images to a signal, before detecting, thresholding and editing peaks to optimize profiles. Such treated profiles (21 positive and 15 negative) are compared to ground truth analysis of an expert biologist. 16 profiles over 21 are well detected positive and 12 profiles over 15 are detected negative, results seem similar to inter-experts variability reported in literature.

Tear analysis as a tool to detect oligoclonal bands in radiologically isolated syndrome.

BACKGROUND: Although radiologically isolated syndrome (RIS) is a newly defined entity, incidental findings of T2 hypersignals on brain MRI can lead to misdiagnosis or useless investigations. The detection of oligoclonal bands (OCBs) in cerebrospinal fluid (CSF) is a major indicator that helps in diagnosis of subclinical inflammatory disease of the central nervous system, but lumbar puncture still remains an invasive option. METHODS: We have prospectively included patients with RIS, have compared the results of CSF and tear OCB detection by isoelectric focusing (IEF) and assessed concordance between OCB detection in tears and in CSF. Tears were collected using a Schirmer strip. RESULTS: In 45 recruited RIS patients, OCBs were detected in CSF for 55% (25/45) and in tears for 50% (21/42) of samples. CONCLUSIONS: We suggest that tear OCB detection may replace CSF OCB detection as a diagnostic tool in patients with RIS and be useful in follow-up.

Improvements of Adaptive Filtering by Optimal Projection to filter different artifact types on long duration EEG recordings.

Adaptive Filtering by Optimal Projection (AFOP) is an automatic method for reducing ocular and muscular artifacts on electro-encephalographic (EEG) recordings. This paper presents two additions to this method: an improvement of the stability of ocular artifact filtering and an adaptation of the method for filtering electrode artifacts. With these improvements, it is possible to reduce almost all the current types of artifacts, while preserving brain signals, particularly those characterising epilepsy. This generalised method consists of dividing the signal into several time-frequency windows, and in applying different spatial filters to each. Two steps are required to define one of these spatial filters: the first step consists of defining artifact spatial projection using the Common Spatial Pattern (CSP) method and the second consists of defining EEG spatial projection via regression. For this second step, a progressive orthogonalisation process is proposed to improve stability. This method has been tested on long-duration EEG recordings of epileptic patients. A neurologist quantified the ratio of removed artifacts and the ratio of preserved EEG. Among the 330 artifacted pages used for evaluation, readability was judged better for 78% of pages, equal for 20% of pages, and worse for 2%. Artifact amplitudes were reduced by 80% on average. At the same time, brain sources were preserved in amplitude from 70% to 95% depending on the type of waves (alpha, theta, delta, spikes, etc.). A blind comparison with manual Independent Component Analysis (ICA) was also realised. The results show that this method is competitive and useful for routine clinical practice.

[Screening for diabetic retinopathy using a three-field digital nonmydriatic fundus camera in the North of France]. / Dépistage de la rétinopathie diabétique par télémédecine en utilisant des rétinophotographies non mydriatiques dans un groupe hospitalier du Nord-Pas-de-Calais.

PURPOSE: To evaluate screening for diabetic retinopathy, using three-field nonmydriatic fundus photography, combined with telemedicine, in two hospitals. METHODS: Patients from the Endocrinology Department of Saint Philibert Hospital were screened consecutively from March 2007 to September 2008. Three 45 degrees digital images per eye examination were taken using a nonmydriatic fundus camera and sent by intranet to the Department of Ophthalmology of Saint Vincent de Paul Hospital for grading by two ophthalmologists. RESULTS: A total of 1147 patients (52% males, 48% females) were screened. The mean age was 60 years (range, 19-92 years). Most patients had type 2 diabetes (n=1000; 90%). The mean HbA1c was 8%. Microalbuminuria was detected in 239 patients (20.8%). Of these 1147 patients, 521 (45%) said they had never had a fundus examination before. Fundus photography of at least one eye could not be graded in 160 patients (14%). Diabetic retinopathy was detected in 187 patients (19%). Suspected macular edema (hard exudates within one disc diameter of the macular center) was found in 38 patients (3.8%). Referral to an ophthalmologist was required in 347 patients (30%) for diabetic retinopathy and unreadable photographs. During the period of the study, 107 patients had both three-field nonmydriatic photography and dilated funduscopy, which was used as reference. Agreement between the two readers was 0.97. CONCLUSIONS: Nonmydriatic photography combined with telemedicine is useful for screening for diabetic retinopathy and identifies patients requiring further complete eye examination. Good collaboration between the two centers is required to improve the follow-up after screening in the future.

[Reliability of immunoturbidimetric urine albumin determination for normal and moderately high values]. / Fiabilité du dosage immunoturbidimétrique de l'albumine urinaire pour les valeurs normales ou modérément élevées.

The value of albuminuria determination is commonly accepted in the monitoring of renal function, particularly in diabetic patients. This may be achieved in different ways and using different assay kits. The aim of this study was to assess the reliability of immunoturbidimetric measurements by comparing the results obtained by two different methods in our laboratory. Therefore we measured albuminuria of 54 patients monitored for their diabetes, with normal to moderately high albuminuria, according to two methods: Microalbumin reagent (Beckman Coulter) on a Unicel DxC 600 (Beckman Coulter) and Albumin Turbiquant reagent (Dade Behring, Siemens) on a Turbitimer system (Dade Behring, Siemens). It was then possible to study the correlation between the two techniques. Our results suggest that although this correlation is excellent, the values differ significantly: the results observed with the Siemens method are higher by about 10%. It seems legitimate to think that a correction should be applied, depending on the used method. In addition, it appears that standardization is necessary, concerning analytical stage but although urine collection, pre-analytical stage or reporting and interpretation of results.

[Interest of Prom-Test in the follow-up of premature rupture of membranes]. / Place du Prom-Test dans la prise en charge de la rupture prématurée des membranes.

The follow-up of premature rupture of membranes requires an hospitalization. The aim of this work was to evaluate the interest of the Prom-Test in the action to be taken in the case of a suspicion of premature rupture of membranes, a negative result allowing to not hospitalize the patient. 105 tests have been carried out producing 73 negative results, 23 positive and 9 doubtful. The childbirth, started or not, occurred much more quickly when the test is positive. Only 13 of the 73 negative tests resulted in a hospitalization including 11 for beginning of delivery. A correct use of the test can prevent unnecessary days of hospitalization.

[Hyperhomocysteinaemia and type 2 diabetes]. / Hyperhomocystéinémie et diabète de type 2.

OBJECTIVES: Hyperhomocysteinaemia is associated with cardiovascular events in nondiabetic individuals. The present study was aimed to explore the implication of hyperhomocysteinemia in development of cardiovascular events in patients with type 2 diabetes. DESIGN: A total of 185 patients with type 2 diabetes (115 women and 70 men, 30 to 93 years of age) have been included consecutively in the ambulatory unit at the Saint-Philibert Hospital. For each patient the concentration of homocysteine, cholesterol and triglyceride levels and HbA1c have been measured. In the studied population, 121 patients presented cardiovascular events (myocardial infarctus, peripheric arteriopathy, cerebrovascular accident). RESULTS: The patients with cardiovascular events were older, the concentration of homocysteine and creatinine were higher. The plasma homocysteine levels adjusted for age and creatinine levels were higher in patients with cardiovascular events than in patients without cardiovascular events (15.4 +/- 3.52 micromol/L and 13.13 +/- 2.26 micromol/L respectively; p = 2. 10(-5)). CONCLUSIONS: Hyperhomocysteinemia is an independant risk factor for cardiovascular events in type 2 diabetes, independent of age and renal function.

[Proposed reference values for nine methods for measurement of free thyroxin]. / Proposition de valeurs de référence pour neuf techniques de dosage de la thyroxine libre dans le sérum.

In connection with a comparative study of nine kits for the measurement of free thyroxin, we determined reference values in a adult control group of 81 women and 73 men. The correlations observed between the kits are associated with very large differences in the results obtained. The reference ranges are more or less broad according to the kits, but narrower than those offered by the manufacturers.

Patency and limb salvage after distal prosthetic bypass associated with vein cuff and arteriovenous fistula.

OBJECTIVE: To assess the usefulness of vein cuff with or without arteriovenous fistula interposition as adjuvant techniques for improving patency and limb salvage in patients undergoing femorodistal bypass surgery using prosthetic grafts. METHOD: We undertook a retrospective study of 65 consecutive patients treated over a 5-year period with 67 prosthetic femorodistal bypasses with vein cuff, in whom an arteriovenous fistula was constructed at the distal anastomosis in 35. Patients were followed for a median time period of 23 months. RESULTS: Primary patency rates were 68, 53 and 44% at 1, 2 and 3 years, respectively. The corresponding figures for secondary patency, limb survival and patients' survival were 73, 64 and 58% for 1 year, 78, 76 and 73% for 2 years and 72, 66 and 63% for 3 years. None of the criteria analyzed influenced patency or limb salvage on prosthetic bypasses using adjuvant techniques. No statistical differences were found between patency and limb salvage rates in patients for whom the vein cuff was constructed with or without an arteriovenous fistula. But patients who managed with a supplementary arteriovenous fistula had significantly fewer distal residual arteries in the limb (p=0.001). CONCLUSION: Although results in patients treated with adjunctive techniques differed little from those in patients treated with direct prosthetic bypasses procedures, those who eventually had an adjunctive procedure had inferior runoff. This indicates that an arteriovenous fistula might be a valuable supplement in patients with poor runoff who have distal revascularisation using a prosthetic graft.

[Usual values for 5-hydroxy-indol acetic acid and homovanillic acid in cerebrospinal fluid]. / Etablissement de valeurs usuelles pour les acides 5-hydroxyindolacétique et homovanilliquedans le liquide céphalorachidien.

The aim of this work was to reinvestiagte usual values of neurotransmitter catabolites (5-HIAA and HVA) in CSF, their determination being a current method for studying pathological processes and/or drug induced changes on CNS metabolism. 5-HIAA and HVA have been measured by reverse phase HPLC and electrochemical detection. Since many confounding factors have been identified to modify the concentration of both analytes in CSF, data from 1.480 patients have been revisited with strict exclusion and 323 have been selected. Age dependent variation and asymetric distributions were observed. Age-related usual values ranges were established after identification of outliers by non-parametric analysis. In a group of patients for which repeated CSF collection have been performed for the follow up of acute leukemia, wide and unpredictible individual variations (up to 400 %) of CSF 5-HIAA and HVA concentrations have been observed. These large interindividual and individual variations may explain the numerous discrepancies found in studies investigating the CNS monoamine metabolism, especially when small groups of patients are used. Such observation limits the interpretation of monoamine metabolic for diagnostic purposes without a strict selection of indication.

[Use of formulas for calculating serum osmolality]. / De l'usage des formules de calcul de l'osmolalité sérique.

Osmolality can be measured or calculated. More than ten formulas have been proposed for calculating serum osmolality from chemical concentrations. The aim of this work was to compare results obtained whith some of these formulas, those calculated in the laboratory using a multiple regression model and measurements with an osmometer. Scattered results for natremia and chloremia, depending on the automate, led us to define formulas adapted for each measurement system in order to reduce the risk of error in the evaluation of the " osmolar gap ".

[Comparison of spectral analysis and non-linear analysis of EEG in patients with cognitive decline]. / Comparaison de l'analyse spectrale et de l'analyse non-linéaire de l'EEG dans les troubles cognitifs.

Twenty-five elder subjects were classified in two groups according to the MMS score and the cognitive evoked potentials. Normal subjects (n = 15) had mean MMS = 27.6 and mean P3 amplitude = 7.1 uV), while patients with cognitive decline (n = 10) had respective values of 18 (MMS) and 3.3 uV (P3). Spectral analysis and non-linear analysis of EEG (recurrence plots of dynamical systems) were performed and both showed statistically significant differences between groups for all the parameters analysed. Subjects' classification with discriminant analysis was slightly better using the non-linear parameters. The recurrence plot method applied to EEGs, gave similar results as the dimension of correlation (D2) calculation, and was in favour of a more constraint and less complex dynamics of brain activity associated with cognitive decline.

Silver stained isoelectrophoresis of tears and cerebrospinal fluid in multiple sclerosis.

Cerebrospinal fluid (CSF) analysis aids in the diagnosis of multiple sclerosis. However, this examination is invasive. The aim of this study was to assess the potentials of a new method of tears isoelectrophoresis (IEF). Silver staining of IEF was used to examined tears and CSF from 123 patients including 60 patients with multiple sclerosis (MS), 50 other neurological patients and 13 patients with inflammatory neurological diseases. Tears were collected on a Shirmer strip placed in one eye, avoiding reflex secretion. This method of IEF with silver staining allowed the detection of oligoclonal bands in tears that were truly immunoglobulin G on immunofixation. The concordance rate between tears and CSF was 83%, meaning that CSF provided no more information than tears analysis in 83% of cases. Sensitivity in tears (72%) and CSF (75%) was very close as was specificity (respectively 84 % and 86 %). High concordance between tears and CSF is the first step in developing a non invasive test which could replace lumbar puncture, particularly when this procedure is not fearalele or is refused by the patient.