Huntington's disease: new aspects on phenotype and genotype

Huntington's disease typically presents with involuntary movements, cognitive decline and behavioural abnormalities; however, new data show a greater spectrum and more complexity in the mode of presentation than previously appreciated. On one hand efforts are under way to better assess all aspects of the evolving phenotype over the course of the disease, on the other hand large cohorts have been prospectively followed-up and similar efforts are now being started in China. In this communication, we briefly review the most salient findings from the last couple of years. The recently established large cohorts allow the performance of accurate studies examining correlation of genetic polymorphisms with specific aspects of the phenotype thus allowing for some mechanistic insight into the causes of phenotypic variation. While Huntington's disease is the most frequent hereditary cause of chorea, other disorders with similar clinical phenotypes, including neuroacanthocytosis, are now better known, including a better understanding of the primary cause as well as the pathophysiology at the molecular level. Studies on the mechanisms of disease in these different disorders may shed light on the respective pathomechanisms and may open new approaches to a better understanding and additional treatment options for choreatiform neurodegenerative disorders.

Deep brain stimulation of the globus pallidus internal improves symptoms of chorea-acanthocytosis

Chorea-acanthocytosis is a rare autosomal recessive disorder. To date, treatment is only symptomatic and supportive. Results from the few reports of chorea-acanthocytosis patients treated with deep brain stimulation (DBS) have been inconsistent. We present case reports for two patients with chorea-acanthocytosis who received DBS treatment and compare the outcomes with results from the literature. Both patients showed the typical clinical features of chorea-acanthocytosis with motor symptoms resistant to medical treatment. Chorea was significantly improved following low-frequency DBS treatment in both patients. However, dystonia was only mildly improved. Four chorea-acanthocytosis patients treated with DBS treatment have been reported in the literature. One patient had improvement with low-frequency DBS stimulation, while another two had improvement with higher-frequency DBS. One patient, however, did not improve with either low-frequency or high-frequency DBS. Bilateral DBS to the GPi can improve chorea and dystonia in some patients with intractable chorea-acanthocytosis. However, selection criteria for the most promising candidates must be defined, and the long-term benefits evaluated in clinical studies.

Cross-sectional observational study of 208 patients with non-classical urea cycle disorders

Urea cycle disorders (UCDs) are inherited disorders of ammonia detoxification often regarded as mainly of relevance to pediatricians. Based on an increasing number of case studies it has become obvious that a significant number of UCD patients are affected by their disease in a non-classical way: presenting outside the newborn period, following a mild course, presenting with unusual clinical features, or asymptomatic patients with only biochemical signs of a UCD. These patients are surviving into adolescence and adulthood, rendering this group of diseases clinically relevant to adult physicians as well as pediatricians. In preparation for an international workshop we collected data on all patients with non-classical UCDs treated by the participants in 20 European metabolic centres. Information was collected on a cohort of 208 patients 50% of which were ≥ 16 years old. The largest subgroup (121 patients) had X-linked ornithine transcarbamylase deficiency (OTCD) of whom 83 were female and 29% of these were asymptomatic. In index patients, there was a mean delay from first symptoms to diagnosis of 1.6 years. Cognitive impairment was present in 36% of all patients including female OTCD patients (in 31%) and those 41 patients identified presymptomatically following positive newborn screening (in 12%). In conclusion, UCD patients with non-classical clinical presentations require the interest and care of adult physicians and have a high risk of neurological complications. To improve the outcome of UCDs, a greater awareness by health professionals of the importance of hyperammonemia and UCDs, and ultimately avoidance of the still long delay to correctly diagnose the patients, is crucial.

Deficiency in SLC25A1, encoding the mitochondrial citrate carrier, causes combined D-2- and L-2-hydroxyglutaric aciduria

The Krebs cycle is of fundamental importance for the generation of the energetic and molecular needs of both prokaryotic and eukaryotic cells. Both enantiomers of metabolite 2-hydroxyglutarate are directly linked to this pivotal biochemical pathway and are found elevated not only in several cancers, but also in different variants of the neurometabolic disease 2-hydroxyglutaric aciduria. Recently we showed that cancer-associated IDH2 germline mutations cause one variant of 2-hydroxyglutaric aciduria. Complementary to these findings, we now report recessive mutations in SLC25A1, the mitochondrial citrate carrier, in 12 out of 12 individuals with combined D-2- and L-2-hydroxyglutaric aciduria. Impaired mitochondrial citrate efflux, demonstrated by stable isotope labeling experiments and the absence of SLC25A1 in fibroblasts harboring certain mutations, suggest that SLC25A1 deficiency is pathogenic. Our results identify defects in SLC25A1 as a cause of combined D-2- and L-2-hydroxyglutaric aciduria.

Pancreatic carcinoma, pancreatitis, and healthy controls: metabolite models in a three-class diagnostic dilemma

Metabolomics as one of the most rapidly growing technologies in the "-omics" field denotes the comprehensive analysis of low molecular-weight compounds and their pathways. Cancer-specific alterations of the metabolome can be detected by high-throughput mass-spectrometric metabolite profiling and serve as a considerable source of new markers for the early differentiation of malignant diseases as well as their distinction from benign states. However, a comprehensive framework for the statistical evaluation of marker panels in a multi-class setting has not yet been established. We collected serum samples of 40 pancreatic carcinoma patients, 40 controls, and 23 pancreatitis patients according to standard protocols and generated amino acid profiles by routine mass-spectrometry. In an intrinsic three-class bioinformatic approach we compared these profiles, evaluated their selectivity and computed multi-marker panels combined with the conventional tumor marker CA 19-9. Additionally, we tested for non-inferiority and superiority to determine the diagnostic surplus value of our multi-metabolite marker panels. Compared to CA 19-9 alone, the combined amino acid-based metabolite panel had a superior selectivity for the discrimination of healthy controls, pancreatitis, and pancreatic carcinoma patients [Formula: see text] We combined highly standardized samples, a three-class study design, a high-throughput mass-spectrometric technique, and a comprehensive bioinformatic framework to identify metabolite panels selective for all three groups in a single approach. Our results suggest that metabolomic profiling necessitates appropriate evaluation strategies and-despite all its current limitations-can deliver marker panels with high selectivity even in multi-class settings.

Fatal myocardial infarction at 4.5 years in a case of homozygous familial hypercholesterolaemia

Management of homozygous familial hypercholesterolaemia is notoriously difficult. For these patients, LDL apheresis is considered the treatment of choice. Treatment initiation is advocated generally from the age of seven years onwards (Thompson et al., Atherosclerosis 198:247-255, 2008). Here, we present the case of a young girl from a large inbred family of Turkish descent with homozygous familial hypercholesterolaemia and fatal outcome at the early age of 4(1/2) years.In conclusion, this case suggests that management of homozygous familial hypercholesterolaemia may require earlier and more aggressive treatment, including LDL apheresis before the age of seven years.

Elimination of chronic viral infection by blocking CD27 signaling

Neutralizing antibody (nAb) responses to lymphocytic choriomeningitis virus (LCMV) in mice and immunodeficiency virus and hepatitis C virus in humans are usually weak and slow to develop. This may be the result of structural properties of the surface glycoprotein, a low frequency of B cells with neutralizing specificity, and the necessity of prolonged affinity maturation of specific nAbs. In this study, we show that during LCMV infection, CD27 signaling on CD4+ T cells enhances the secretion of interferon-gamma and tumor necrosis factor-alpha. These inflammatory cytokines lead to the destruction of splenic architecture and immunodeficiency with reduced and delayed virus-specific nAb responses. Consequently, infection with the otherwise persistent LCMV strain Docile was eliminated after CD27 signaling was blocked. Our data provide a novel mechanism by which LCMV avoids nAb responses and suggest that blocking the CD27-CD70 interaction may be an attractive strategy to prevent chronic viral infection.

Pilot study on the comprehensive economic costs of major trauma: Consequential costs are well in excess of medical costs

BACKGROUND: Trauma care is expensive. However, reliable data on the exact lifelong costs incurred by a major trauma patient are lacking. Discussion usually focuses on direct medical costs--underestimating consequential costs resulting from absence from work and permanent disability. METHODS: Direct medical costs and consequential costs of 63 major trauma survivors (ISS >13) at a Swiss trauma center from 1995 to 1996 were assessed 5 years posttrauma. The following cost evaluation methods were used: correction cost method (direct cost of restoring an original state), human capital method (indirect cost of lost productivity), contingent valuation method (human cost as the lost quality of life), and macroeconomic estimates. RESULTS: Mean ISS (Injury Severity Score) was 26.8 +/- 9.5 (mean +/- SD). In all, 22 patients (35%) were disabled, causing discounted average lifelong total costs of USD 1,293,800, compared with 41 patients (65%) who recovered without any disabilities with incurred costs of USD 147,200 (average of both groups USD 547,800). Two thirds of these costs were attributable to a loss of production whereas only one third was a result of the cost of correction. Primary hospital treatment (USD 27,800 +/- 37,800) was only a minor fraction of the total cost--less than the estimated cost of police and the judiciary. Loss of quality of life led to considerable intangible human costs similar to real costs. CONCLUSIONS: Trauma costs are commonly underestimated. Direct medical costs make up only a small part of the total costs. Consequential costs, such as lost productivity, are well in excess of the usual medical costs. Mere cost averages give a false estimate of the costs incurred by patients with/without disabilities.

Tocopherol-associated protein-1 accelerates apoptosis induced by alpha-tocopheryl succinate in mesothelioma cells

Alpha-tocopheryl succinate (alpha-TOS), a redox-silent analogue of vitamin E, induces apoptosis in multiple cell lines in a selective manner, by activating the intrinsic pathway. Since it is a highly hydrophobic compound, it may require a carrier protein for its trafficking to intracellular targets like mitochondria. We studied the role of the ubiquitous tocopherol-associated protein-1 (TAP1 or sec14-like 2) in apoptosis induction by alpha-TOS in malignant mesothelioma (MM) cells. Over-expression of TAP1 in MM cells sensitised them to apoptosis by low doses of alpha-TOS which were sub-apoptotic for the parental cells. Apoptosis induced in TAP1-over-expressing cells was mitochondria- and caspase-dependent, as suggested by dissipation of mitochondrial trans-membrane potential and inhibition by zVAD-fmk, respectively. Binding assays showed affinity of alpha-TOS for TAP1. Finally, TAP1 over-expressing cells accumulated alpha-TOS at higher levels compared to their normal counterparts. We suggest that TAP1 may act as an intracellular shuttle for alpha-TOS, promoting apoptosis initiated by this vitamin E analogue, as shown here for MM cells.

The effect of tocopheryl phosphates on atherosclerosis progression in rabbits fed with a high cholesterol diet

The effect of tocopheryl phosphate on atherosclerosis progression has been studied in rabbits, fed with a 2% cholesterol diet and compared with an equivalent amount of alpha-tocopheryl acetate. The results show that the atherosclerotic-preventing effect of the phosphate derivative was more pronounced than that of the acetate derivative. alpha-Tocopheryl phosphate was also more potent in diminishing the expression of CD36 than the acetate derivative.

Increased expression of transglutaminase-1 and PPARgamma after vitamin E treatment in human keratinocytes

In skin, vitamin E acts as the predominant lipophilic antioxidant with a protective function against irradiation and oxidative stress. In addition to that, vitamin E can also modulate signal transduction and gene expression. To study whether the four natural tocopherol analogues (alpha-, beta-, gamma-, delta-tocopherol) can influence transcriptional activity by modulating the activity of nuclear receptors, a human keratinocytes cell line (NCTC 2544) was transfected with plasmids containing the luciferase reporter gene under control by direct repeat elements (DR1-DR4), representing binding sites for four different classes of nuclear receptors. In this model, the tocopherols positively modulated only the reporter construct containing a consensus element for peroxisome proliferator-activated receptors (PPARs). The induction was strongest with gamma-tocopherol and was most likely the direct consequence of stimulation of PPARgamma protein expression in keratinocytes. Vitamin E treatment also led to increased expression of a known PPARgamma target gene involved in terminal keratinocytes differentiation, the transglutaminase-1.

The effect of gamma-tocopherol on proliferation, integrin expression, adhesion, and migration of human glioma cells

The effect of vitamin E on proliferation, integrin expression, adhesion, and migration in human glioma cells has been studied. gamma-tocopherol at 50 microM concentration exerted more inhibitory effect than alpha-tocopherol at the same concentration on glioma cell proliferation. Integrin alpha5 and beta1 protein levels were increased upon both alpha- and gamma-tocopherol treatments. In parallel, an increase in the alpha5beta1 heterodimer cell surface expression was observed. The tocopherols inhibited glioma cell-binding to fibronectin where gamma-tocopherol treatment induced glioma cell migration. Taken together, the data reported here are consistent with the notion that the inhibition of glioma cell proliferation induced by tocopherols may be mediated, at least in part, by an increase in integrin alpha5 and beta1 expression. Cell adhesion is also negatively affected by tocopherols, despite a small increase in the surface appearance of the alpha5beta1 heterodimer. Cell migration is stimulated by gamma-tocopherol. It is concluded that alpha5 and beta1 integrin expression and surface appearance are not sufficient to explain all the observations and that other integrins or in general other factors may be associated with these events.

Antagonistic effects of oxidized low density lipoprotein and alpha-tocopherol on CD36 scavenger receptor expression in monocytes: involvement of protein kinase B and peroxisome proliferator-activated receptor-gamma

Vitamin E deficiency increases expression of the CD36 scavenger receptor, suggesting specific molecular mechanisms and signaling pathways modulated by alpha-tocopherol. We show here that alpha-tocopherol down-regulated CD36 expression (mRNA and protein) in oxidized low density lipoprotein (oxLDL)-stimulated THP-1 monocytes, but not in unstimulated cells. Furthermore, alpha-tocopherol treatment of monocytes led to reduction of fluorescent oxLDL-3,3'-dioctadecyloxacarbocyanine perchlorate binding and uptake. Protein kinase C (PKC) appears not to be involved because neither activation of PKC by phorbol 12-myristate 13-acetate nor inhibition by PKC412 was affected by alpha-tocopherol. However, alpha-tocopherol could partially prevent CD36 induction after stimulation with a specific agonist of peroxisome proliferator-activated receptor-gamma (PPARgamma; troglitazone), indicating that this pathway is susceptible to alpha-tocopherol action. Phosphorylation of protein kinase B (PKB) at Ser473 was increased by oxLDL, and alpha-tocopherol could prevent this event. Expression of PKB stimulated the CD36 promoter as well as a PPARgamma element-driven reporter gene, whereas an inactive PKB mutant had no effect. Moreover, coexpression of PPARgamma and PKB led to additive induction of CD36 expression. Altogether, our results support the existence of PKB/PPARgamma signaling pathways that mediate CD36 expression in response to oxLDL. The activation of CD36 expression by PKB suggests that both lipid biosynthesis and fatty acid uptake are stimulated by PKB.

Vitamin E inhibits CD36 scavenger receptor expression in hypercholesterolemic rabbits

A numerous studies suggest that Vitamin E has a preventive role in atherosclerosis, although the mechanism of action still remains unclear. CD36, a member of the scavenger receptor family is centrally involved in the uptake of oxidized low density proteins (oxLDLs) from bloodstream. During the atherosclerotic process, the lipid cargo of oxLDL accumulates in macrophages and smooth muscle cells, inducing their pathological conversion to foam cells. In the present study, we investigate the role of Vitamin E on CD36 expression in an in vivo model. Atherosclerosis was induced by a 2% cholesterol containing Vitamin E poor diet. Three groups of six rabbits each were studied. The first group (control) was fed on Vitamin E poor diet. The second group was fed with Vitamin E poor diet containing 2% cholesterol and the rabbits in the third group were fed with Vitamin E poor diet containing 2% cholesterol and received injections of 50 mg/kg of Vitamin E i.m. After 4 weeks, aortas were removed and analysed by light microscopy for atherosclerotic lesions. Aortic samples were analysed for CD36 mRNA expression. The aortas of cholesterol-fed rabbits showed typical atherosclerotic lesions, detected by macroscopic and microscopic examination, and exhibited an increase in CD36 mRNA expression. Vitamin E fully prevented cholesterol induced atherosclerotic lesions and the induction of CD36 mRNA expression. The effects observed at the level of CD36 scavenger receptor expression in vivo suggest an involvement of reduced foam cell formation in the protective effect of Vitamin E against atherosclerosis.

Modulation of signal transduction by vitamin E

The ability of vitamin E to modulate signal transduction and gene expression has been observed in numerous studies; however, the detailed molecular mechanisms involved are often not clear. The eight natural vitamin E analogues and synthetic derivatives affect signal transduction with different potency, possibly reflecting their different ability to interact with specific proteins. Vitamin E modulates the activity of several enzymes involved in signal transduction, such as protein kinase C, protein kinase B, protein tyrosine kinases, 5-, 12-, and 15-lipoxygenases, cyclooxygenase-2, phospholipase A2, protein phosphatase 2A, protein tyrosine phosphatase, and diacylglycerol kinase. Activation of some these enzymes after stimulation of cell surface receptors with growth factors or cytokines can be normalized by vitamin E. At the molecular level, the translocation of several of these enzymes to the plasma membrane is affected by vitamin E, suggesting that the modulation of protein-membrane interactions may be a common theme for vitamin E action. In this review the main effects of vitamin E on enzymes involved in signal transduction are summarized and the possible mechanisms leading to enzyme modulation evaluated. The elucidation of the molecular and cellular events affected by vitamin E could reveal novel strategies and molecular targets for developing similarly acting compounds.