Pelizaeus-Merzbacher disease (PMD) is a rare X-linked recessive neurologic disorder caused by a mutation in the proteolipid protein (PLP) gene on chromosome Xq22. The associated depletion of PLP and ...severe reduction of other major myelin proteins results in dysmyelination. MRI reveals loss of T1 contrast between gray and affected white matter and T2 hyperintensities of white matter due to elevated water content.
In vivo proton magnetic resonance spectroscopy (MRS) was used to determine cerebral metabolite patterns in five patients with genetically proven PMD. Absolute metabolite concentrations were obtained in cortical gray matter, affected white matter, and basal ganglia and compared to age-matched control values.
In comparison to age-matched controls, MRS of affected white matter resembled the metabolite pattern of cortical gray matter, as indicated by increased concentrations of N-acetylaspartate and N-acetylaspartylglutamate (tNAA), glutamine (Gln), myo-inositol (Ins), and creatine and phosphocreatine. Most remarkably, the concentration of choline-containing compounds was reduced. Parietal gray matter and basal ganglia appeared normal but showed a tendency for elevated tNAA, Gln, and Ins.
Magnetic resonance spectroscopy (MRS)-detected alterations are consistent with enhanced neuroaxonal density, astrogliosis, and reduction of oligodendroglia. These disturbances in cellular composition are in close agreement with the histopathologic features characteristic of dys- and hypomyelination. The proton MRS profile of Pelizaeus-Merzbacher disease (PMD) differs from the pattern commonly observed in demyelinating disorders and allows PMD to be distinguished from other leukodystrophies.
Anti-oxidant treatment has been shown to prevent nerve dysfunction in experimental diabetes mellitus, thus providing a rationale of potential therapeutic value for diabetic patients. The effects of ...the anti-oxidant alpha-lipoic acid (thioctic acid) were studied in a 3-week multicentre, randomized, double-blind placebo-controlled trial (Alpha-Lipoic Acid in Diabetic Neuropathy; ALADIN) in 328 non-insulin-dependent diabetic patients with symptomatic peripheral neuropathy who were randomly assigned to treatment with intravenous infusion of alpha-lipoic acid using three doses (1200, 600, or 100 mg ALA) or placebo (PLAC). Neuropathic symptoms (pain, burning, paraesthesiae, and numbness) were scored at baseline and at each visit (days 2-5, 8-12, and 15-19) prior to infusion. In addition, the Hamburg Pain Adjective List, a multidimensional specific pain questionnaire, and the Neuropathy Symptom and Disability Scores were assessed at baseline and day 19. According to the protocol 260 (65/63/66/66) patients completed the study. The total symptom score in the feet decreased from baseline to day 19 by -4.5 +/- 3.7 (-58.6%) points (mean +/- SD) in ALA 1200, -5.0 +/- 4.1 (-63.5%) points in ALA 600, -3.3 +/- 2.8 (-43.2%) points in ALA 100, and -2.6 +/- 3.2 (-38.4%) points in PLAC (ALA 1200 vs PLAC: p = 0.003; ALA 600 vs PLAC: p < 0.001). The response rates after 19 days, defined as an improvement in the total symptom score of at least 30%, were 70.8% in ALA 1200, 82.5% in ALA 600, 65.2% in ALA 100, and 57.6% in PLAC (ALA 600 vs PLAC; p = 0.002). The total scale of the Pain Adjective List was significantly reduced in ALA 1200 and ALA 600 as compared with PLAC after 19 days (both p < 0.01). The rates of adverse events were 32.6% in ALA 1200, 18.2% in ALA 600, 13.6% in ALA 100, and 20.7% in PLAC. These findings substantiate that intravenous treatment with alpha-lipoic acid using a dose of 600 mg/day over 3 weeks is superior to placebo in reducing symptoms of diabetic peripheral neuropathy, without causing significant adverse reactions.
Cerebral metabolic disturbances in patients with childhood adrenoleukodystrophy (ALD) were assessed by quantitative localized proton MRS. Patient monitoring by follow-up MRS studies served to ...identify putative markers for disease onset and progression. Whereas normal-appearing white matter of neurologically asymptomatic patients is characterized by slightly elevated concentrations of choline-containing compounds (Cho), an increase of both Cho and myo-inositol (Ins) seems to indicate the onset of demyelination. Markedly elevated concentrations of Cho, Ins, and glutamine in affected white matter reflect active demyelination and glial proliferation. A simultaneous reduction of the concentrations of N-acetylaspartate and glutamate is consistent with neuronal damage or loss. The observation of elevated lactate is in line with inflammation and/or macrophage infiltration. The more severe metabolic disturbances in cerebral ALD correspond to progressive demyelination, neuroaxonal loss and gliosis leading to clinical deterioration and eventually death. The detection of MRS abnormalities before the onset of neurological symptoms may help in the selection of patients for bone marrow transplantation (BMT). Stabilization and partial reversal of metabolic abnormalities is demonstrated in a patient after BMT.
Megalencephalic leukoencephalopathy with subcortical cysts (MLC) was recently localized on chromosome 22q (tel) and 26 different mutations of the gene MLC1 have been found. We report three siblings ...of non-consanguineous parents who presented with characteristic features of MLC, but did not have MLC1 mutations. MEYHODS: Clinical, laboratory and neuro-imaging findings of the siblings are described and similar patients with MLC are reviewed.
All three siblings suffered from ataxia, progressive severe tetraparesis, dysarthria, dysphagia and epilepsy. Generalized dystonia occurred in one patient. Mental deterioration progressed more slowly than motor deterioration. The youngest male was the most severely affected and died at the age of 23 years. The two older females are now 34 and 35 years old. Our patients are among the oldest described with this clinical entity. No mutation of the MLC1 gene was found in our siblings and linkage with the MLC1 locus was excluded.
The genetic findings in our patients suggest at least a second gene locus for MLC.
About 35-40 % of boys with X-linked adrenoleukodystrophy (ALD) develop a rapidly progressive cerebral form which leads to severe neurologic disability and death within 3-5 years after onset of ...clinical symptoms. Because previous proton magnetic resonance spectroscopy (MRS) studies of ALD identified metabolite patterns characteristic of demyelination, gliosis, and neuroaxonal loss, this work tested the hypothesis that MRS--apart from indicating disease progression--provides criteria for the outcome after hematopoietic stem cell transplantation (HSCT) which has been promising at an early stage of the active disease. Follow-up quantitative proton MRS was performed in frontal and occipital white matter of ALD patients (n = 12) before and up to 5 years after HSCT. The observed metabolite alterations were retrospectively correlated with the clinical outcome representing either a stable condition (n = 5), a further deterioration (n = 5), or death (n = 2). While disease progression of patients before HSCT was mainly characterized by a further increase of elevated choline-containing compounds (Cho) as an indicator of active demyelination, a positive outcome after HSCT was correlated with high N-acetylaspartate (tNAA) levels in affected white matter before HSCT yielding positive and negative predictive values for tNAA of 80 %. Although to be confirmed in a larger cohort of patients, the present findings suggest the preservation of neuroaxonal integrity as a prerequisite for an arrested course. Conversely, the combination of increased Cho with markedly reduced tNAA before HSCT apparently reflects a degree of tissue degeneration which precludes a successful therapeutic intervention.
The mitochondrial encephalomyopathies are chronic progressive disorders affecting predominantly the neuromuscular system. Symptoms are induced by insufficient energy supply resulting from a ...deficiency of oxidative phosphorylation. We studied one male and four female patients with genetically proven mitochondrial encephalomyopathy. Their ages ranged from 7 to 19 years (two with Kearns-Sayre syndrome, one patient with neuronal muscle weakness, ataxia, and retinitis pigmentosa syndrome, and two patients with mitochondrial myopathy, encephalopathy, lactic acidosis, and stroke-like episodes), using a retrospective study method. We studied the effect of creatine supplementation (0.08 g-0.35 g/kg body weight/day; 9 months to 4 years, 10 months) and measured skeletal muscle power analysis (bicycle ergometer). After creatine supplementation all patients demonstrated an increase in their maximum performance (W) (+4% − +30%; mean: +12.1%). These results indicate an improved aerobic oxidative function of mitochondria after creatine administration in patients with mitochondrial encephalomyopathies. Continuous physical exercise was improved to a greater extent than instantaneous activity.
A neurodegenerative disorder characterized by megalencephaly since early infancy and slowly progressive symptoms of cerebellar, pyramidal, and extrapyramidal dysfunction, pseudobulbar signs, and ...epilepsy was detected in an 8-year-old girl with severe neuromotor handicap but preservation of mental and sensory functions. Cranial computed tomography and magnetic resonance imaging revealed brain swelling as well as severe abnormalities of frontal, temporal, and parietal white matter, with an extended cystlike appearance isointense to cerebrospinal fluid. Localized proton magnetic resonance spectroscopy of affected cystic white matter showed a loss of all metabolites, in accordance with a complete disintegration of neuroaxonal and glial tissue. This case is likely a severe variant of a recently described megalencephalic leukoencephalopathy with swelling and discrepantly mild clinical course.
Acyltransferase from Mycobacterium smegmatis is a versatile enzyme, which catalyzes the transesterification of esters in aqueous media due to a kinetic preference of the synthesis reaction over the ...thermodynamically favored hydrolysis reaction. In the active octamer, the active site is deeply buried and connected to the protein surface by long and hydrophobic substrate access channels. The role of the access channel in controlling catalytic activity and substrate specificity was investigated by molecular dynamics simulations and Markov-state models, and the thermodynamics and kinetics of binding of acyl donors, acceptors, and water were compared. Despite the hydrophobic nature of the substrate access channel, water is present in the channel and competes with the acyl acceptors for access to the active site. The binding free energy profiles in the access channel and the flux of butyl and benzyl alcohol and vinyl acetate were analyzed in the concentration range between 10 and 500 mM and compared to water. The flux showed a maximum at an alcohol concentration of 50–100 mM, in agreement with experimental observations. At the maximum, the flux of alcohol approaches 50% of the flux of water, which explains the high transesterification rate as compared to hydrolysis. The molecular origin of this effect is due to the accumulation of alcohol molecules along the access channel. Extensive molecular dynamics simulations and analysis of trajectories by a Markov-state model provided insights into the role of the access channel in activity and specificity by controlling access and binding of competing substrates.
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