Neurophysiological localisation of ulnar neuropathy at the elbow: Validation of diagnostic criteria developed by a taskforce of the Danish Society of clinical neurophysiology.

OBJECTIVE: This study validates consensus criteria for localisation of ulnar neuropathy at elbow (UNE) developed by a taskforce of the Danish Society of Clinical Neurophysiology and compares them to the existing criteria from the American Association of Neuromuscular and Electrodiagnostic Medicine (AANEM). The Danish criteria are based on combinations of conduction slowing in the segments of the elbow and forearm expressed in Z-scores, and difference between the segments in m/s. Examining fibres to several muscles and sensory fibres can increase the certainty of the localisation. METHODS: Diagnostic accuracy for UNE was evaluated on 181 neurophysiological studies of the ulnar nerve from 171 peer-reviewed patients from a mixed patient-group. The diagnostic reference standard was the consensus diagnosis based on all available clinical, laboratory, and electrodiagnostic information reached by a group of experienced Danish neurophysiologists. RESULTS: The Danish criteria had high specificity (98.4%) and positive predictive value (PPV) (95.2%) and fair sensitivity (76.9%). Compared to the AANEM criteria, the Danish criteria had higher specificity (p<0.001) and lower sensitivity (p=0.02). CONCLUSIONS: The Danish consensus criteria for UNE are very specific and have high PPV. SIGNIFICANCE: The Danish criteria for UNE are reliable and well suited for use in different centres as they are based on Z-scores.

Haemodynamic parameters and cognitive function during modeled acute volume loss.

PURPOSE: The purpose of the present study was to find a noninvasive way of detecting even smaller volume loss which is easier to carry out and possibly more precise than the currently used (mostly sphygmomanometer-based) methods. Haemodynamic and EEG measurements were carried out in simulated volume loss, involving blood donation and orthostatic challenges to assess adaptive responses and cognitive performance. Cognitive performance was assessed in an oddball task and changes of the evoked potential P300 were analyzed. Both haemodynamic and cognitive parameters were recorded in 'pre-donation' and 'post-donation' conditions for purposes of comparison. RESULTS: Cognitive performance (as reflected by P300 changes) was found to be a poor marker of volume loss. Difference between the two conditions in none of the parameters reached the level of statistical significance (defined as p < 0.05) RR mean, baroreceptor sensitivity and pulse pressure were rather sensitive to the relatively mild volume loss (p < 0.01 between pre- and post-conditions). CONCLUSION: Our study indicates that traditional sphygmomanometer based values can safely be replaced by values yielded by finger plethysmography, combined with brief orthostatic challenges and that P300 as a cognitive marker cannot be used to assess volume loss.

Factors influencing the health-related quality of life in Hungarian multiple sclerosis patients.

BACKGROUND: The 'Multiple Sclerosis Quality of Life Instrument' (MSQOL-54) was recently validated in Hungarian, on more than 400 multiple sclerosis (MS) patients. The aim of the present study was to examine the impact on their overall quality of life (QoL) of the demographic and clinical data on these patients, and their scores on different QoL scales. METHODS: The Hungarian version of MSQOL-54 was given to patients at the outpatient units at the Department of Neurology, University of Szeged, and two other Hungarian MS centres. Additional data, including the EDSS scores of the patients, and relevant clinical and demographic data, were also collected. RESULTS: The questionnaire scales relating to social function, general health, mental health and satisfaction with the sexual function mostly determined the overall QoL ratings. 62.1% of the patients indicated at least one comorbid condition. Depressed patients had a significantly worse quality of life (p<0.0001). CONCLUSIONS: MSQOL-54 is a useful tool for the recognition of possibly treatable factors influencing the QoL, but not assessed by the EDSS. Quality of life data have emerged on more than 400 patients, i.e. a considerable proportion of the Hungarian MS patient population.

Chromosomal rearrangements after ex vivo Epstein-Barr virus (EBV) infection of human B cells.

The Epstein-Barr virus (EBV) is carried by more than 90% of the adult world population and has been implicated in several human malignancies. Its ability to induce unlimited in vitro proliferation of B cells is frequently used to generate lymphoblastoid cell lines (LCLs). In this study, we have investigated the evolution of two LCLs up to 25 weeks after EBV infection. LCLs were karyotyped once a month by spectral karyotyping (SKY). LCLs but not mitogen-activated B cells showed evidence of DNA damage and DNA damage response within the first 2 weeks. After 4 weeks, the former, but not the latter, showed a high level of non-clonal structural aberrations, mainly deletions, fragments, dicentric chromosomes and unbalanced translocations. Genomic instability decreased thereafter over time. Nonrandom aneuploidy 12 weeks after infection showed clonal evolution in culture. After 25 weeks post-infection, most cells exhibited karyotypic stability. Chromosomal aberrations were compatible with telomere dysfunction, although in the absence of telomere shortening. The telomere capping protein TRF2 was partially displaced from telomeres in EBV-infected cells, suggesting an EBV-mediated uncapping problem. In conclusion, this study suggests that DNA damage and telomere dysfunction contribute to EBV-related chromosomal instability in early LCLs.

Effects of moderate hypobaric hypoxia on evoked categorical visuocognitive responses.

OBJECTIVE: Aim of the current study is to provide electrophysiological evidence about the effects of moderate hypobaric hypoxia on human visual cognition. METHODS: We investigate ERPs at occipitoparietal cortical areas in an ultra-rapid categorical discrimination task with psychomotor responses under the conditions of normoxia vs. moderate hypobaric hypoxia. Subjects had to produce motor response upon the categorization of target images containing animals, while suppress it for nontarget images containing only nonanimals. RESULTS: Statistical analysis on peak amplitudes and latencies of ERP components indicated significant: (i) attenuation of P1 and enhancement of N1-P3 amplitudes, (ii) delay of P2 latency for both stimuli whereas the delay of P3 latency only for nontargets, (iii) reduction in behavioral performance rates only for nontargets. CONCLUSIONS: For both categorical stimuli, impairment of early visual sensory and compensation through late cognitive processes was noticed. For targets, compensatory discrimination-categorization processes (reflected on P3 amplitudes) were sufficient to override our mild transient hypoxic challenge. For nontargets, differential P3 latencies and behavioral performance manifested the early impeding effects of systemic hypoxaemia. SIGNIFICANCE: Evoked brain responses allow for early detection of subtle electrophysiological modulations coupled to cognitive-behavioral alterations, assessment of 'functional' hypobaric hypoxic sensitivity thresholds for 'altinauts' and reveal the susceptibilities of complex visuocognitive processes even to moderate hypoxic insults.

Cross-cultural adaptation and validation of the 'Multiple Sclerosis Quality of Life Instrument' in Hungarian.

Health-related quality of life measurements are gaining more importance in the study and clinical practice of multiple sclerosis. The aim of our study was the adaptation of the Multiple Sclerosis Quality of Life Instrument (MSQOL-54) in Hungarian. The study was carried out at the Department of Neurology, University of Szeged and two other multiple sclerosis centers. The Hungarian translation of the questionnaire was given to patients at the outpatient units of the neurology departments. The EDSS score of the patients were determined and data concerning the onset and the clinical form of the disease was collected. Altogether 438 patients filled out the questionnaire. We enrolled patients with all clinical forms of the disease. Cronbach's alpha coefficients were over 0.8 in case of all scales except ;Rolelimitations - emotional' (0.794), indicating a good internal consistency reliability for group comparisons. The instrument was able to distinguish between known clinical group differences. The Hungarian version of the MSQOL-54 instrument shows good psychometric properties similar to the original questionnaire.

Comparison of clinical symptoms and magnetic resonance angiographic (MRA) results in patients with trigeminal neuralgia and persistent idiopathic facial pain. Medium-term outcome after microvascular decompression of cases with positive MRA findings.

Neurovascular compression (NC) seems to have been confirmed as the major cause of classical trigeminal neuralgia (TN). In spite of the large number of surgically positive cases, however, there are still cases where no vascular compression of the trigeminal nerve can be found. To evaluate whether NC could be demonstrated preoperatively, high-resolution magnetic resonance angiography (MRA) was performed in 287 consecutive patients with TN and persistent idiopathic facial pain (PIFP) on a 0.5-T and a 1-T MR unit. Depending on the clinical symptoms, the TN cases were divided into typical TN and trigeminal neuralgia with non-neuralgic interparoxysmal pain (TNWIP) groups. Microvascular decompression (MVD) was performed in 103 of the MRA-positive cases. The patients were followed up postoperatively for from 1 to 10 years. The clinical symptoms were compared with the imaging results. The value of MRA was assessed on the basis of the clinical symptoms and surgical findings. The outcome of MVD was graded as excellent, good or poor. The clinical symptoms were compared with the type of vascular compression and the outcome of MVD. The MRA image was positive in 161 (56%) of the 287 cases. There were significant differences between the clinical groups: 66.5% of the typical TN group, 47.5% of the TNWIP group and 3.4% of the PIFP group were positive. The quality of the MR unit significantly determined the ratio of positive/negative MRA results. The surgical findings corresponded with the MRA images. Six patients from the MRA-negative group were operated on for selective rhizotomy and no NC was found. Venous compression of the trigeminal nerve was observed in a significantly higher proportion in the background of TNWIP than in that of typical TN on MRA imaging (24.1% and 0.8%, respectively) and also during MVD (31.2% and 1.2%, respectively). Four years following the MVD, 69% of the patients gave an excellent, 23% a good and 8% a poor result. The rate of some kind of recurrence of pain was 20% in the typical TN and 44% in TNWIP group. The rate of recurrence was 57% when pure venous compression was present. The only patient who was operated on from the PIFP group did not react to the MVD. The clinical symptoms and preoperative MRA performed by at least a 1-T MR unit furnish considerable information, which can play a role in the planning of the treatment of TN.

Spatial contrast sensitivity of migraine patients without aura.

Visual disturbances are frequent symptoms in migraine. Since there is a possibility of separate damage in the magno- or parvo-cellular visual pathway in migraine patients, we performed a study including the measurement of static and dynamic spatial contrast sensitivity on 15 patients suffering from migraine without aura under photopic and scotopic conditions. Fifteen healthy volunteers without primary headache served as controls. The results revealed a marked decrease in contrast sensitivity at low spatial frequencies in the migraine patients. Spatial contrast sensitivity demonstrated some lateralization, as the sensitivity to low spatial frequencies obtained through separate eyes showed significantly larger side-differences in migraine patients than in control subjects. These findings suggest that the mechanisms responsible for vision at low spatial frequencies are impaired in migraine patients. This might indicate impaired function of the magnocellular pathways in this condition.

Kinetics of recombinant human brain-derived neurotropic factor unfolding under reversed-phase liquid chromatography conditions.

A model describing the pathway of unfolding of recombinant human brain-derived neurotrophic factor (rhBDNF) under reversed-phase high-performance liquid chromatographic conditions is introduced. The unfolding process is divided into two major steps. The first entails a series of events such as the dissociation of the dimer and the effect of the initial contact of the protein with the stationary phase. The second step is the unfolding of the monomer molecule on the hydrophobic surface exhibiting a rate constant comparable with the time scale of chromatography. The kinetics of rhBDNF unfolding is studied with respect to the type and composition of the organic solvents and as function of the temperature of chromatography. The experimental results validate the suggested multistep unfolding model. The activation energy of monomer unfolding in both solvent systems studied is similar, but the unfolding processes are different in 1-propanol and in acetonitrile.

Conformational changes of brain-derived neurotrophic factor during reversed-phase high-performance liquid chromatography.

Recombinant human brain-derived neurotrophic factor (r-HuBDNF) is eluted as two peaks under reversed-phase liquid chromatographic conditions with gradient elution. Sodium dodecyl sulfate polyacrylamide gel electrophoresis confirmed identical molecular weights in the two peaks, while rechromatography of the separated peaks showed interconvertibility. The two peaks are identified as the monomeric forms of the parent molecules. The molecular weight of the components in the peaks was determined by on-line 90 degree light scattering using a fluorescence detector as a scatterograph. The early eluted peak is a folded form of the r-HuBDNF monomer, while the later eluted peak is an unfolded form of the BDNF monomer. The conformational states were established using a fluorescence detector both at a fixed wavelength and in the scanning mode.

"Paralogs", sorbent families for protein separations.

Novel peptide-based (paralog) sorbents are evaluated with respect to performance, reproducibility and reusability in a 96-well test plate screening format, and to utility in protein separations. The results demonstrate that this approach to constructing sorbents provides a new and generally applicable set of tools for separating proteins.

Application of Fourier transform infrared spectroscopy to studies of aqueous protein solutions.

Modern protein Fourier transform infrared (FT-IR) spectroscopy has proven to be a versatile and sensitive technique, applicable to many aspects of protein characterization. The major practical drawback for the FT-IR spectroscopy of proteins is the large absorbance band of water, which overlaps the amide I resonances. D2O is often substituted for H2O in infrared experiments. Removal of water from protein samples can be complicated and tedious and potentially lead to denaturation, aggregation, or sample loss. Solvent removal by dialysis is difficult for suspensions and sols. A new method called the D2O dilution technique (Ddt) is described which simplifies the sample preparation step and improves the solvent subtraction. The effect of the D2O concentration on the IR spectrum of aqueous solutions of several model proteins was studied. Dilution of aqueous samples with D2O yields good quality spectra. The Ddt has been evaluated for quantitative analysis using standard proteins and its applicability to solutions and suspensions of a genetically engineered malaria antigen is demonstrated. Use of resolution-enhancement techniques with spectra in mixed solvents has also been investigated.

Reversed-phase liquid chromatography and sodium dodecyl sulfate polyacrylamide gel electrophoresis characteristics of a recombinant DNA derived malaria antigen.

This paper presents results from analysis of a sample of SK&F 105154 (R32NS1(81], a malaria vaccine candidate produced in Escherichia coli, and discusses some analytical issues of general relevance to the characterization of such products derived from recombinant DNA technology. Anomalous migration and staining behavior were observed in sodium dodecyl sulfate polyacrylamide gel electrophoresis (SDS-PAGE). Reversed-phase liquid chromatography (RPLC) appeared to resolve four minor components from the principal band, but the minor peaks were found to consist of numerous components resolvable by SDS-PAGE. Western blotting visualized certain components that were not adequately stained by either Coomassie or silver stain. None of the techniques that were employed were individually adequate to characterize the sample, but, taken together, were adequate to characterize the sample and to identify one principal degradation pathway. Degradation within the NS1(81) region decreases the RPLC retention time, while degradation within the R32 segment increases the retention time.

Thermal behavior of proteins in high-performance hydrophobic-interaction chromatography. On-line spectroscopic and chromatographic characterization.

The thermal behavior of a series of standard proteins in hydrophobic interaction chromatography on a previously developed weakly hydrophobic ether-bonded phase column has been studied. Depending on the temperature and protein, conformational changes can occur in the chromatographic system. Methods for recognizing these conformational effects are presented, including retention and peak width variations with temperature, and Z values (the slope of the plot of log k' vs. log %B solvent. The Z value is shown to be a general index characterizing protein retention as a function of salt concentration. In addition, on-line UV spectroscopic analysis, (absorbance ratios and second derivative spectroscopy) with a photodiode array detector, is shown to corroborate chromatographic trends. Lysozyme maintains a stable conformation over the temperature range 10-40 degrees C, whereas beta-lactoglobulin A has a conformational transition between 25 degrees C and 40 degrees C. Calcium-depleted alpha-lactalbumin, a rather labile species, maintains a stable conformation up to ca. 20 degrees C, and then undergoes structural changes. Finally, cytochrome c appears to be relatively stable up to ca. 65 degrees C. Since conformational changes for this protein occur at ca. 35 degrees C on more hydrophobic phases, the extent of hydrophobicity of the stationary phase is important for maintenance of the native state. Based on this work, hydrophobic-interaction chromatography at sub-ambient temperatures appears promising.

Conformational effects in the high-performance liquid chromatography of proteins. Further studies of the reversed-phase chromatographic behavior of ribonuclease A.

This paper is a continuation of an examination of the conformational effects of ribonuclease A (RNase A) in reversed-phase liquid chromatography. RNase A is a particularly good example of reversible conformational refolding during chromatographic elution. Absorbance ratio measurements with a photodiode-array detector are consistent with a two-state model in which an early eluted broad band is associated with the folded or native state and a late eluted sharp band is associated with an unfolded state. By varying the mobile phase flow-rate while maintaining the mean capacity factor (k') of the protein in gradient elution constant, the apparent rate constant of refolding in the mobile phase was measured and found to be comparable with that reported in the literature. It has been further shown that, as the gradient steepness parameter b or mean k' value is altered, the apparent rate constant also changes, as a result of variation in mobile phase composition. The apparent rate constant as a function of temperature was also found to reach a maximum at 20 degrees C. Based on the results of this model system, it is possible to predict optimum conditions for elution of species with sharp elution peaks when reversible refolding takes place in the column.

Effect of histamine-receptor blocking on human natural and lectin-dependent cell-mediated cytotoxicity against adherent HEP-2 cells.

The effect of histamine (H) and H1-, H2-receptor blocking agents was studied on natural (NCMC) and lectin-dependent cell-mediated cytotoxicity (LDCC) of peripheral blood lymphocytes (PBL) from eight healthy subjects on HEP-2 adherent human epipharynx carcinoma target cells. Cytotoxicity was measured by detachment from the monolayer of 3H-TdR-prelabelled HEp-2 cells. LDCC was evaluated in a 24 h assay with a Concanavalin A (Con A) dose of 25 micrograms/ml at 50:1 effector-target cell ratio. Under these conditions, but without Con A, considerable NCMC was not elicited by normal lymphocytes. The presence of histamine and the H2-receptor blocker cimetidine resulted in a significant NCMC to HEp-2 cells. On the contrary, histamine and cimetidine reduced LDCC. The H1-receptor blocker clemastine had no significant effect on either NCMC or LDCC to HEp-2 targets. The possible involvement of H2-receptor bearing cells in the regulation of cytotoxicity to HEp-2 cells is suggested.

Conformational effects in the reversed-phase liquid chromatography of ribonuclease A.

This paper examines the reversed-phase liquid chromatographic behavior of ribonuclease A (RNase) using an n-butyl chemically bonded phase and a gradient of 10 mM H3PO4 and l-propanol. At a column temperature of 25 degrees C, a broad band followed by an overlapped late-eluting sharp peak is observed. As the temperature is raised, the sharp peak grows at the expense of the broad band until at 37 degrees C, only a single narrow-eluting band is found. Using an absorbance ratio of A288/A254, it is demonstrated that the broad band represents a folded or native state of RNase and the late-eluting band a denatured state. Based on postcolumn absorbance ratio changes in the denatured state as a function of time and the known behavior of the protein, reversible refolding or renaturation is proposed to take place in solution. RNase is denatured upon adsorbing to the bonded phase, and upon migration down the column, reversible refolding takes place in the mobile phase. The relaxation time for native state formation is assumed to be comparable to the time spent by RNase in the mobile phase. As temperature is raised, both the native and denatured states exist at equilibrium in solution, thus slowing the refolding process, until at 37 degrees C only the denatured peak appears. Changes in peak shape with flow rate provide further evidence for this model. The use of HCl or H2SO4 instead of H3PO4 yields similar results except that the temperature at which only the denatured peak is observed follows the order of salt stabilization of the native state.

Kinetics of unfolding of proteins on hydrophobic surfaces in reversed-phase liquid chromatography.

As a continuation of previous studies, we present in this paper measurements on the kinetics of denaturation of papain, soybean trypsin inhibitor and lysozyme on n-butyl-bonded silica gel surfaces used in reversed-phase liquid chromatography (RPLC). In all cases, native and denatured peaks widely separated from one another are observed. The rate constants for denaturation or unfolding are determined by the measurement of the peak area of the native protein as a function of the incubation time that the species spends on the bonded-phase surface. The results reveal that a slow denaturation step occurs with a half-life of ca. 15 min. In addition, studies of denaturation as a function of the amount of 1-propanol in the initial mobile phase suggest an additional unfolding step when the protein comes in contact with the bonded-phase surface. The extent of this latter step decreases as the concentration of 1-propanol increases, further suggesting that 1-propanol sorption on the bonded stationary phase may play a role in this behavior. Other studies are conducted with alpha-chymotrypsinogen, in which injection is made after the start of the gradient. The extent of denaturation is observed to be a function of the organic modifier employed. The results of this paper provide insight into the denaturation process in RPLC and suggest approaches to minimize this behavior.

Mobile-phase and temperature effects in the reversed phase chromatographic separation of proteins.

This paper explores the influence of mobile-phase and temperature effects on the gradient elution reversed phase chromatographic behavior of proteins. Using LiChrospher SI 500, bonded with n-butyl groups and a gradient in 1-propanol, 10 mM H3PO4, rapid separation and high mass recovery were obtained for a series of globular proteins. This protein separation and recovery are compared to those obtained when acetonitrile and acetonitrile plus 10 mM H3PO4 are used as eluting gradient solvents. In general, acetonitrile yielded lower recovery than 1-propanol, particularly for the more hydrophobic proteins, e.g., ovalbumin. For all three gradient solvents, little difference was observed in retention or recovery when the n-alkyl chain of the bonded phase varied. On the other hand, relative to the n-alkyl phases, a significantly lower retention of all proteins was found on more hydrophilic phases, e.g., cyano and nonendcapped n-butyl, when acetonitrile was the organic modifier, while in the case of 1-propanol, no retention difference was observed. Thus, column comparisons depend on the protein/mobile-phase combinations examined. The role of column temperature was also studied, and it was found that for certain proteins dramatic changes in peak shape occurred as a function of temperature. The influences of ionic strength and salt type were also studied. Protein mass recovery was shown to decrease with an increase in salt concentration; moreover, perchlorate was shown to have a larger effect in this regard than phosphate. In addition, salt concentration and type were found to influence peak shape greatly in certain cases. The results indicate the strong influences of mobile phase and temperature on chromatographic behavior, and some of the options available when this behavior is not satisfactory. Several protein separations are presented illustrating the power of the reversed phase approach.

Characterization of the effector cells in Con A-induced cytotoxicity against HEp 2 tumour targets.

Con A-induced cytotoxic activity of human lymphocyte subpopulations obtained by cell fractionation procedures was studied in a test system using human epipharynx carcinoma cells (HEp 2) as targets. Only T lymphocytes were cytotoxic, non-T cells exerted no cytotoxic activity, but enhanced the adherence of the tumour cells. Tnon-G lymphocytes (Fc-receptor negative T cells) were more active than TG cells (Fc-receptor-positive T cells) in mediating the Con A-induced cytotoxic reaction.