Pyridoxine dependent epilepsy: Is late onset a predictor for favorable outcome?

AIM: In pyridoxine dependent epilepsy (PDE), patients usually present with neonatal seizures. A small subgroup is characterized by late-onset beyond 2 months of age. We aim to analyze the observation of relatively good cognitive outcome in this subgroup of late-onset PDE patients. METHODS: We retrospectively analyzed data from four metabolically and genetically confirmed late-onset patients with PDE due to antiquitin (ALDH7A1) deficiency. Data were analyzed regarding ALDH7A1 mutations, alpha-Aminoadipic semialdehyde (α-AASA) and pipecolic acid (PA) levels, medication during pregnancy, delivery, treatment delay, amount of seizures, pyridoxine dose, adjuvant therapy and findings on brain MRI. RESULTS: Results showed that three patients had relatively good outcome (IQ 80-97), while one patient did not undergo formal testing and was considered mildly delayed. We were unable to find a clear association between the above-mentioned variables and cognitive outcome, although a less severe genotype may be present in three patients, and maternal medication could be accountable for better outcome in two patients. INTERPRETATION: We suggest that favorable outcome in late onset PDE might be explained by a combination of factors. A yet unknown protective factor, different genetic variations, functional variation and secondarily variation in treatment regimens and absence of neonatal seizure induced brain damage.

Chemodenervation for treatment of limb spasticity following spinal cord injury: a systematic review.

STUDY DESIGN: Systematic review. OBJECTIVES: To systematically review the literature on chemodenervation with botulinum toxin (BoNT) or phenol/alcohol for treatment of limb spasticity following spinal cord injury (SCI). SETTING: British Columbia, Canada. METHODS: EMBASE, MEDLINE, CINAHL, Cochrane Database of Systematic Reviews and Cochrane Central Register of Controlled Trials were searched for English language studies published up until March 2014. Studies were assessed for eligibility and quality by two independent reviewers. RESULTS: No controlled trials were identified. A total of 19 studies were included: 9 involving BoNT and 10 involving phenol/alcohol. Owing to the clinically diverse nature of the studies, meta-analysis was deemed inappropriate. The studies produced level 4 and level 5 evidence that chemodenervation with BoNT or alcohol/phenol can lead to improvement in outcome measurements classified in the body structure and function, as well as activity domains of the International Classification of Functioning, Disability and Health framework. The Modified Ashworth Scale (MAS) was the most commonly used outcome measure. All six studies on BoNT and three of the four studies on phenol/alcohol measuring MAS reported a decrease in at least one point. An improvement in MAS was not always associated with improvement in function. The effect of phenol/alcohol has the potential to last beyond 6 months; study follow-up did not occur beyond this time point. CONCLUSION: Chemodenervation with BoNT or phenol/alcohol may improve spasticity and function in individuals with SCI. However, there is a lack of high-quality evidence and further research is needed to confirm the efficacy of these interventions.

Autonomic function as a missing piece of the classification of paralympic athletes with spinal cord injury.

OBJECTIVE: When someone suffers a spinal cord injury (SCI) many organs, including those of the cardiovascular (CV) system, cease to be controlled by the autonomic nervous system (ANS). Response to physical activity fails to meet the needs of the body and typically results in low blood pressure (BP), and in turn, reduced endurance and performance. This study examines the effect of SCI on the ANS of elite athletes and possible effect on their CV functions and ultimately their performance. The study also provides input on evidence of boosting and the current classification system. Finally, authors are exploring a possibility for future research in assessing whether consideration of ANS function would strengthen current Paralympic classification systems. STUDY DESIGN: MEDLINE, SportDiscus, Embase databases and the official Paralympic website were reviewed. In total, 60 manuscripts and five website documents were reviewed. RESULT: Athletes with high-level SCI affecting the ANS have limited ability to regulate their heart rate and BP in response to exercise. According to current Paralympic classification systems, these athletes are grouped with competitors who have similar motor control but intact ANS, thereby potentially putting them at a disadvantage within their own classification category. High-level SCI athletes with ANS dysfunction are also the only athletes who experience episodes of autonomic dysreflexia (AD). Whereas AD is a state of uninhibited sympathetic discharge, it is called 'boosting' when intentionally induced during competition. Boosting has been shown to improve sporting performance but can also cause serious complications due to extreme rises in BP. Therefore, boosting has been banned by the International Paralympic Committee (IPC). Despite this ban some elite high-level SCI athletes continue to boost. The IPC recognizes that the current classification systems are not the gold standard and further work is needed to create a more evidence-based classification. CONCLUSIONS: Further research is needed to determine if the inclusion of ANS parameters contributes to strengthen classifications systems in Paralympic sports. This includes the development of a simple, valid and reliable bedside assessment of autonomic function that can be used to reliably compare athletes with or without ANS dysfunction thereby enabling further research into the isolated effect of ANS dysfunction on sporting performance. Researchers who are studying individuals with SCI, and who have CV parameters as their outcomes, should ensure a homogenous study group by the presence or absence of ANS function in addition to level of lesion so as to eliminate the potential for confounding variables that lead to inaccurate interpretation of results.

Pyridoxal 5'-phosphate may be curative in early-onset epileptic encephalopathy.

Neonatal epileptic encephalopathy can be caused by inborn errors of metabolism. These conditions are often unresponsive to treatment with conventional antiepileptic drugs. Six children with pyridox(am)ine-5'-phosphate oxidase (PNPO) deficiency presented with neonatal epileptic encephalopathy. Two were treated with pyridoxal 5'-phosphate (PLP) within the first month of life and showed normal development or moderate psychomotor retardation thereafter. Four children with late or no treatment died or showed severe mental handicap. All of the children showed atypical biochemical findings. Prompt treatment with PLP in all neonates and infants with epileptic encephalopathy should become mandatory, permitting normal development in at least some of those affected with PNPO deficiency.

Mass spectrometric analysis of glycans in elucidating the pathogenesis of CDG type IIx .

The majority of secreted or membrane-bound proteins are glycosylated. The glycans attached to glycoproteins can affect a range of physicochemical and biological properties of the glycoprotein and appropriate glycosylation is essential for many normal cellular functions, with aberrant glycosylation often leading to disease. This short review briefly outlines the methodology used to release glycans from proteins and analyse them by mass spectrometry. The technology is illustrated by the description of a rapid and sensitive method for profiling glycoproteins of patients with congenital disorders of glycosylation type II. This methodology can rapidly pinpoint the defective step(s) in the processing pathway of N-linked glycans, thereby focusing the biochemical analyses that need to be performed to define the genetic basis of these diseases.

Analysis by matrix assisted laser desorption/ionisation-time of flight mass spectrometry of the post-translational modifications of alpha 1-antitrypsin isoforms separated by two-dimensional polyacrylamide gel electrophoresis.

The state of protein glycosylation in terms of occupation of potential N-linked glycosylation sites (macroheterogeneity) and type of glycosylation at that site (microheterogeneity) is important when investigating the consequences of aberrant glycosylation in the pathophysiology of disease. Protocols have been developed to permit characterisation of the site-specific glycosylation of individual isoforms of glycoproteins after separation by two-dimensional polyacrylamide gel electrophoresis (2D-PAGE) and analysis of the peptide mixture by peptide mass fingerprinting using matrix-assisted laser desorption/ionisation-time of flight mass spectrometry (MALDI-TOF). High resolution of the individual isoforms of alpha 1-antitrypsin was achieved by using narrow range (4.5-5.5) p/strips. The individual isoforms were then subjected to sequential digestion with a recombinant N-glycanase followed by a protease. Using this strategy it was possible not only to increase the coverage of the amino acid sequence but also to monitor the occupancy of all three putative N-linked glycosylation sites. Glycans were enzymatically released from alpha 1-antitrypsin which had been separated in gels formed with a low percentage of bis-acrylamide cross-linker and analysed. Profiles of the N-linked glycans of the individual isoforms of alpha 1-antitrypsin were obtained by MALDI-TOF.

Identification of alpha(1)-antitrypsin variants in plasma with the use of proteomic technology.

BACKGROUND: Proteomic technology permits the investigation of genetic metabolic diseases at the level of protein expression. Changes in the expression, polypeptide structure, and posttranslational modification of individual proteins can be detected in complex mixtures of proteins. METHODS: We used high-resolution two-dimensional polyacrylamide gel electrophoresis to separate isoforms of plasma proteins and detect abnormalities of mass and/or charge. We confirmed the identity of the separated proteins by in-gel digestion with proteases and N-glycanases and then analyzed the released peptides and glycans by matrix-assisted laser-desorption ionization-time-of-flight mass spectrometry. RESULTS: Complete characterization of the polypeptide sequences and glycosylation of alpha(1)-antitrypsin isoforms was achieved in plasma from controls and from patients with three different known alpha(1)-antitrypsin deficiencies and congenital disorder of glycosylation type Ia. CONCLUSIONS: This study shows that proteomic techniques are a powerful and sensitive means of detecting changes in the amino acid sequence and abnormal posttranslational modifications of specific proteins in a complex biologic matrix.

Substitutions of glutamate 781 in the Na,K-ATPase alpha subunit demonstrate reduced cation selectivity and an increased affinity for ATP.

The intramembrane Glu781 residue of the Na,K-ATPase alpha subunit has been postulated to have a role in the binding and/or occlusion of cations. To ascertain the role of Glu781, the residue was substituted with an aspartate, alanine, or lysine residue and the mutant Na,K-ATPases were coexpressed with the native beta 1 subunit in Sf9 insect cells using the baculovirus expression system. All alpha mutants are able to efficiently assemble with the beta 1 subunit and produce catalytically competent Na,K-ATPase molecules with hydrolytic activities comparable to that of the wild-type enzyme. Analysis of the kinetic properties of the mutated enzymes showed a decrease in apparent affinity for K+ compared to wild-type Na,K-ATPase, with the lysine and alanine substitutions displaying the greatest reduction. All Na,K-ATPase mutants demonstrated a significant increase in apparent affinity for ATP compared to wild-type Na,K-ATPase, while the sensitivity to the cardiotonic inhibitor, ouabain, was unchanged. The dependence on Na+, however, differs among the mutant enzymes with both the Glu781-->Asp and Glu781-->Ala mutants displaying a decrease in the apparent affinity for the cation, while the Glu781-->Lys mutant exhibits a modest increase. Furthermore, in the absence of K+, the Glu781-->Ala mutant displays a Na(+)-ATPase activity and a cellular Na+ influx suggesting that Na+ is substituting for K+ at the extracellular binding sites. The observation that trypsin digestion of the Glu781-->Ala mutant in Na+ medium produces a K(+)-stabilized tryptic fragment also intimates a decreased capacity of the mutant to discriminate between Na+ and K+ at the extracellular loading sites. All together, these data implicate Glu781 of the Na,K-ATPase alpha subunit as an important coordinate of cation selectivity and activation, although the modest effect of Glu781-->Lys substitution seemingly precludes direct involvement of the residue in the cation binding process. In addition, the fifth membrane segment is proposed to represent an important communicative link between the extramembraneous ATP binding domain and the cation transport regions of the Na,K-ATPase.

Acute dichromate poisoning after use of traditional purgatives. A report of 7 cases.

Seven cases of dichromate poisoning after the use of purgative solutions obtained from nyanga (traditional township healers) are reported. The patients all presented in established renal failure requiring dialysis, and all had abnormal liver function tests. One patient who took dichromate orally died from massive gastro-intestinal haemorrhage. Six patients took dichromate solutions as rectal enemas, 2 were left with impaired renal function and 1 required a permanent colostomy as a result of extensive peri-anal necrosis. The clinical presentation of acute renal failure, gastro-intestinal haemorrhage and hepatocellular dysfunction should alert the physician to the possibility of dichromate poisoning. The diagnosis, management and the role of dialysis in dichromate poisoning are reviewed.