Marcel M. Verbeek

Glial and neuronal proteins in serum predict outcome after severe traumatic brain injury.

Objective: To study the ability of glial (glial fibrillary acidic protein [GFAP] and S100b) and neuronal (neuron specific enolase [NSE]) protein levels in peripheral blood to predict outcome after severe traumatic brain injury. Methods: Eighty-five patients with severe traumatic brain injury (admission Glasgow Coma Score [GCS] ≤ 8) were included. Blood samples taken at the time of hospital admission were analyzed for S100b, GFAP, and NSE. Data collected included demographic and clinical variables. Outcome was assessed using the Glasgow Outcome Scale (GOS) at 6 months post injury. Results: The median serum levels of S100b, GFAP, and NSE were raised 18.3 fold (S100b), 4.6 fold (GFAP), and twofold (NSE) compared to normal reference values. S100b, GFAP, and NSE serum levels correlated significantly with the injury severity score and CT findings but not with age, sex, or GCS. S100b, GFAP, and NSE levels were significantly higher in patients who died or had a poor outcome 6 months post injury than in those who were alive or had good outcome. S100b level >1.13 μg/L was the strongest predictor of death with 100% discrimination, but GFAP (>1.5 μg/L) and NSE (>21.7 μg/L) levels also strongly predicted death (adjusted odds ratios 5.82 [for GFAP] and 3.91 [for NSE]). S100b, GFAP, and NSE all strongly predicted poor outcome (adjusted odds ratios 5.12 [S100b], 8.82 [GFAP], and 3.95 [NSE]). Conclusions: These results suggest that determination of serum levels of glial and neuronal proteins may add to the clinical assessment of the primary damage and prediction of outcome after severe traumatic brain injury.

Glucose transporter-1 deficiency syndrome: the expanding clinical and genetic spectrum of a treatable disorder

Glucose transporter-1 deficiency syndrome is caused by mutations in the SLC2A1 gene in the majority of patients and results in impaired glucose transport into the brain. From 2004-2008, 132 requests for mutational analysis of the SLC2A1 gene were studied by automated Sanger sequencing and multiplex ligation-dependent probe amplification. Mutations in the SLC2A1 gene were detected in 54 patients (41%) and subsequently in three clinically affected family members. In these 57 patients we identified 49 different mutations, including six multiple exon deletions, six known mutations and 37 novel mutations (13 missense, five nonsense, 13 frame shift, four splice site and two translation initiation mutations). Clinical data were retrospectively collected from referring physicians by means of a questionnaire. Three different phenotypes were recognized: (i) the classical phenotype (84%), subdivided into early-onset (<2 years) (65%) and late-onset (18%); (ii) a non-classical phenotype, with mental retardation and movement disorder, without epilepsy (15%); and (iii) one adult case of glucose transporter-1 deficiency syndrome with minimal symptoms. Recognizing glucose transporter-1 deficiency syndrome is important, since a ketogenic diet was effective in most of the patients with epilepsy (86%) and also reduced movement disorders in 48% of the patients with a classical phenotype and 71% of the patients with a non-classical phenotype. The average delay in diagnosing classical glucose transporter-1 deficiency syndrome was 6.6 years (range 1 month-16 years). Cerebrospinal fluid glucose was below 2.5 mmol/l (range 0.9-2.4 mmol/l) in all patients and cerebrospinal fluid : blood glucose ratio was below 0.50 in all but one patient (range 0.19-0.52). Cerebrospinal fluid lactate was low to normal in all patients. Our relatively large series of 57 patients with glucose transporter-1 deficiency syndrome allowed us to identify correlations between genotype, phenotype and biochemical data. Type of mutation was related to the severity of mental retardation and the presence of complex movement disorders. Cerebrospinal fluid : blood glucose ratio was related to type of mutation and phenotype. In conclusion, a substantial number of the patients with glucose transporter-1 deficiency syndrome do not have epilepsy. Our study demonstrates that a lumbar puncture provides the diagnostic clue to glucose transporter-1 deficiency syndrome and can thereby dramatically reduce diagnostic delay to allow early start of the ketogenic diet.

Specific association of small heat shock proteins with the pathological hallmarks of Alzheimer's disease brains

The small heat shock protein family (sHsp) comprises molecular chaperones able to interact with incorrectly folded proteins. Alzheimers disease (AD) is characterized by pathological lesions such as senile plaques (SPs), cerebral amyloid angiopathy (CAA) and neurofibrillary tangles (NFTs), predominantly consisting of the incorrectly folded proteins amyloid‐β (Aβ) and tau respectively. The aim of this study was to investigate the association of the chaperones Hsp20, HspB2, αB‐crystallin and Hsp27 with the pathological lesions of AD brains. For this purpose, a panel of well‐characterized antibodies directed against these sHsps was used in immunohistochemistry and immunoblotting. We observed extracellular expression of Hsp20, Hsp27 and HspB2 in classic SPs, and Hsp20 expression in diffuse SPs. In addition, extracellular expression of HspB2 was observed in CAA. Both Hsp27 and αB‐crystallin were also observed in astrocytes associated with both SPs and CAA. Furthermore, none of the sHsps were observed in NFTs in AD brains. We conclude that specific sHsp species may be involved in the pathogenesis of either SPs or CAA in AD.

A worldwide multicentre comparison of assays for cerebrospinal fluid biomarkers in Alzheimer's disease

Background Different cerebrospinal fluid (CSF) amyloid-beta 1–42 (Aβ 1–42), total Tau (Tau) and Tau phosphorylated at threonine 181 (P-Tau) levels are reported, but currently there is a lack of quality control programmes. The aim of this study was to compare the measurements of these CSF biomarkers, between and within centres. Methods Three CSF-pool samples were distributed to 13 laboratories in 2004 and the same samples were again distributed to 18 laboratories in 2008. In 2004 six laboratories measured Aβ 1–42, Tau and P-Tau and seven laboratories measured one or two of these marker(s) by enzyme-linked immunosorbent assays (ELISAs). In 2008, 12 laboratories measured all three markers, three laboratories measured one or two marker(s) by ELISAs and three laboratories measured the markers by Luminex. Results In 2004, the ELISA intercentre coefficients of variance (interCV) were 31%, 21% and 13% for Aβ 1–42, Tau and P-Tau, respectively. These were 37%, 16% and 15%, respectively, in 2008. When we restricted the analysis to the Innotest® (N = 13) for Aβ 1–42, lower interCV were calculated (22%). The centres that participated in both years (N = 9) showed interCVs of 21%, 15% and 9% and intra-centre coefficients (intraCV) of variance of 25%,18% and 7% in 2008. Conclusions The highest variability was found for Aβ 1–42. The variabilities for Tau and P-Tau were lower in both years. The centres that participated in both years showed a high intraCV comparable to their interCV, indicating that there is not only a high variation between but also within centres. Besides a uniform standardization of (pre)analytical procedures, the same assay should be used to decrease the inter/intracentre variation.

Rapid Degeneration of Cultured Human Brain Pericytes by Amyloid β Protein

Abstract: Amyloid β protein (Aβ) deposition in the cerebral arterial and capillary walls is one of the major characteristics of brains from patients with Alzheimers disease and hereditary cerebral hemorrhage with amyloidosis‐Dutch type (HCHWA‐D). Vascular Aβ deposition is accompanied by degeneration of smooth muscle cells and pericytes. In this study we found that Aβ1–40 carrying the “Dutch” mutation (HCHWA‐D Aβ1–40) as well as wild‐type Aβ1–42 induced degeneration of cultured human brain pericytes and human leptomeningeal smooth muscle cells, whereas wild‐type Aβ1–40 and HCHWA‐D Aβ1–42 were inactive. Cultured brain pericytes appeared to be much more vulnerable to Aβ‐induced degeneration than leptomeningeal smooth muscle cells, because in brain pericyte cultures cell viability already decreased after 2 days of exposure to HCHWA‐D Aβ1–40, whereas in leptomeningeal smooth muscle cell cultures cell death was prominent only after 4–5 days. Moreover, leptomeningeal smooth muscle cell cultures were better able to recover than brain pericyte cultures after short‐term treatment with HCHWA‐D Aβ1–40. Degeneration of either cell type was preceded by an increased production of cellular amyloid precursor protein. Both cell death and amyloid precursor protein production could be inhibited by the amyloid‐binding dye Congo red, suggesting that fibril assembly of Aβ is crucial for initiating its destructive effects. These data imply an important role for Aβ in inducing perivascular cell pathology as observed in the cerebral vasculature of patients with Alzheimers disease or HCHWA‐D.

Cerebral Microvascular Amyloid β Protein Deposition Induces Vascular Degeneration and Neuroinflammation in Transgenic Mice Expressing Human Vasculotropic Mutant Amyloid β Precursor Protein

Cerebral vascular amyloid beta-protein (Abeta) deposition, also known as cerebral amyloid angiopathy, is a common pathological feature of Alzheimers disease. Additionally, several familial forms of cerebral amyloid angiopathy exist including the Dutch (E22Q) and Iowa (D23N) mutations of Abeta. Increasing evidence has associated cerebral microvascular amyloid deposition with neuroinflammation and dementia in these disorders. We recently established a transgenic mouse model (Tg-SwDI) that expresses human vasculotropic Dutch/Iowa mutant amyloid beta-protein precursor in brain. Tg-SwDI mice were shown to develop early-onset deposition of Abeta exhibiting high association with cerebral microvessels. Here we present quantitative temporal analysis showing robust and progressive accumulation of cerebral microvascular fibrillar Abeta accompanied by decreased cerebral vascular densities, the presence of apoptotic cerebral vascular cells, and cerebral vascular cell loss in Tg-SwDI mice. Abundant neuroinflammatory reactive astrocytes and activated microglia strongly associated with the cerebral microvascular fibrillar Abeta deposits. In addition, Tg-SwDI mouse brain exhibited elevated levels of the inflammatory cytokines interleukin-1beta and -6. Together, these studies identify the Tg-SwDI mouse as a unique model to investigate selective accumulation of cerebral microvascular amyloid and the associated neuroinflammation.

Age and diagnostic performance of Alzheimer disease CSF biomarkers

Objectives: Core CSF changes in Alzheimer disease (AD) are decreased amyloid β1–42, increased total tau, and increased phospho-tau, probably indicating amyloid plaque accumulation, axonal degeneration, and tangle pathology, respectively. These biomarkers identify AD already at the predementia stage, but their diagnostic performance might be affected by age-dependent increase of AD-type brain pathology in cognitively unaffected elderly. Methods: We investigated effects of age on the diagnostic performance of CSF biomarkers in a uniquely large multicenter study population, including a cross-sectional cohort of 529 patients with AD dementia (median age 71, range 43–89 years) and 304 controls (67, 44–91 years), and a longitudinal cohort of 750 subjects without dementia with mild cognitive impairment (69, 43–89 years) followed for at least 2 years, or until dementia diagnosis. Results: The specificities for subjects without AD and the areas under the receiver operating characteristics curves decreased with age. However, the positive predictive value for a combination of biomarkers remained stable, while the negative predictive value decreased only slightly in old subjects, as an effect of the high AD prevalence in older ages. Conclusion: Although the diagnostic accuracies for AD decreased with age, the predictive values for a combination of biomarkers remained essentially stable. The findings highlight biomarker variability across ages, but support the use of CSF biomarkers for AD even in older populations.

Tyrosine hydroxylase deficiency: a treatable disorder of brain catecholamine biosynthesis

Tyrosine hydroxylase deficiency is an autosomal recessive disorder resulting from cerebral catecholamine deficiency. Tyrosine hydroxylase deficiency has been reported in fewer than 40 patients worldwide. To recapitulate all available evidence on clinical phenotypes and rational diagnostic and therapeutic approaches for this devastating, but treatable, neurometabolic disorder, we studied 36 patients with tyrosine hydroxylase deficiency and reviewed the literature. Based on the presenting neurological features, tyrosine hydroxylase deficiency can be divided in two phenotypes: an infantile onset, progressive, hypokinetic-rigid syndrome with dystonia (type A), and a complex encephalopathy with neonatal onset (type B). Decreased cerebrospinal fluid concentrations of homovanillic acid and 3-methoxy-4-hydroxyphenylethylene glycol, with normal 5-hydroxyindoleacetic acid cerebrospinal fluid concentrations, are the biochemical hallmark of tyrosine hydroxylase deficiency. The homovanillic acid concentrations and homovanillic acid/5-hydroxyindoleacetic acid ratio in cerebrospinal fluid correlate with the severity of the phenotype. Tyrosine hydroxylase deficiency is almost exclusively caused by missense mutations in the TH gene and its promoter region, suggesting that mutations with more deleterious effects on the protein are incompatible with life. Genotype-phenotype correlations do not exist for the common c.698G>A and c.707T>C mutations. Carriership of at least one promotor mutation, however, apparently predicts type A tyrosine hydroxylase deficiency. Most patients with tyrosine hydroxylase deficiency can be successfully treated with l-dopa.

Clinical and biochemical features of aromatic L-amino acid decarboxylase deficiency

Objective: To describe the current treatment; clinical, biochemical, and molecular findings; and clinical follow-up of patients with aromatic l-amino acid decarboxylase (AADC) deficiency. Method: Clinical and biochemical data of 78 patients with AADC deficiency were tabulated in a database of pediatric neurotransmitter disorders (JAKE). A total of 46 patients have been previously reported; 32 patients are described for the first time. Results: In 96% of AADC-deficient patients, symptoms (hypotonia 95%, oculogyric crises 86%, and developmental retardation 63%) became clinically evident during infancy or childhood. Laboratory diagnosis is based on typical CSF markers (low homovanillic acid, 5-hydroxyindoleacidic acid, and 3-methoxy-4-hydroxyphenolglycole, and elevated 3-O-methyl-l-dopa, l-dopa, and 5-hydroxytryptophan), absent plasma AADC activity, or elevated urinary vanillactic acid. A total of 24 mutations in the DDC gene were detected in 49 patients (8 reported for the first time: p.L38P, p.Y79C, p.A110Q, p.G123R, p.I42fs, c.876G>A, p.R412W, p.I433fs) with IVS6+ 4A>T being the most common one (allele frequency 45%). Conclusion: Based on clinical symptoms, CSF neurotransmitters profile is highly indicative for the diagnosis of aromatic l-amino acid decarboxylase deficiency. Treatment options are limited, in many cases not beneficial, and prognosis is uncertain. Only 15 patients with a relatively mild form clearly improved on a combined therapy with pyridoxine (B6)/pyridoxal phosphate, dopamine agonists, and monoamine oxidase B inhibitors.

Protein S-100B, neuron-specific enolase (NSE), myelin basic protein (MBP) and glial fibrillary acidic protein (GFAP) in cerebrospinal fluid (CSF) and blood of neurological patients

In this study, data about protein S-100B, neuron-specific enolase, myelin basic protein and glial fibrillary acidic protein in cerebrospinal fluid and blood of patients with an acute or chronic progressive neurological disorder with brain damage are reviewed. Especially in disorders with acute brain damage, determination of these proteins in CSF and blood can be helpful to establish structural and/or functional brain damage to determine severity and prognosis of the disease process and to monitor treatment effects.