Marinus A. Blankenstein

The S100B protein is associated with brain damage and a breached blood–brain barrier. A previous pilot study showed that high serum levels of S100B are associated with shorter survival in glioma patients. The aim of our study was to assess the prognostic value in terms of survival and longitudinal dynamics of serum S100B for patients with newly diagnosed and recurrent glioma. We obtained blood samples from patients with newly diagnosed and recurrent glioma before the start (baseline) and at fixed time-points during temozolomide chemotherapy. S100B-data were dichotomized according to the upper limit of the reference value of 0.1 μg/L. Overall survival (OS) was estimated with Kaplan–Meier curves and groups were compared with the log rank analysis. To correct for potential confounders a Cox regression analysis was used. We included 86 patients with newly-diagnosed and 27 patients with recurrent glioma. Most patients in both groups had baseline serum levels within normal limits. In the newly diagnosed patients we found no significant difference in OS between the group of patients with S100B levels >0.1 μg/L at baseline compared to those with <0.1 μg/L. In the patients with recurrent glioma we found a significantly shorter OS for patients with raised levels. In both groups, S100B values did not change significantly throughout the course of the disease. Serum S100B levels do not seem to have prognostic value in newly diagnosed glioma patients. In recurrent glioma patients S100B might be of value in terms of prognostication of survival.

Different neurodegenerative disorders such as Alzheimer’s disease (AD) and frontotemporal dementia (FTD) lead to dementia syndromes. Dementia will pose a huge impact on society and thus it is essential to develop novel tools able to detect the earliest, most sensitive, discriminative and dynamic biomarkers for each of the disorders. To date, the most common assays used in large-scale protein biomarker analysis are enzyme-linked immunosorbent assays (ELISA), such as the sandwich immunoassays, which are sensitive, practical and easily implemented. However, due to the novelty of many candidate biomarkers identified during proteomics screening, such assays or the antibodies that specifically recognize the desired marker are often not available. The development and optimization of a new ELISA should be carried out with considerable caution since a poor planning can be costly, ineffective, time consuming and it may lead to a misinterpretation of the findings. Here we describe a specific and detailed workflow to develop and validate new ELISA for a successful and reliable validation of novel dementia biomarkers. The proposed workflow highlights the main issues in the development of an ELISA and covers several critical aspects including production, screening and selection of specific antibodies until optimal fine-tuning of the assay. Although these recommendations

Background: Increased clusterin levels have been reported in brain, cerebrospinal fluid (CSF), and plasma of Alzheimer’s disease (AD) patients. Because changes are also observed in mild cognitive impairment (MCI), a possible relationship between clusterin levels and early neurodegenerative changes in AD was suggested. Objectives: To determine whether clusterin concentrations could 1) serve as a diagnostic marker for AD, 2) predict disease progression in MCI, and 3) correlate with AD-biomarkers. Methods: Clusterin levels in CSF and plasma, as well as AD biomarker levels of A β ₄₂ , Tau, and pTau in CSF and Mini-Mental State Examination scores (MMSE) were determined in 67 controls, 50 MCI, and 107 AD patients. Repeated MMSE was obtained for 44 MCI and 72 AD patients after, on average, 2.7 years. Results: Elevated clusterin concentrations in plasma, but not in CSF, were a risk factor for AD (HR 18.6; 95% CI 2.8–122), and related to cognitive decline in MCI ( r =−0.38; p < 0.01). An inverse relation between plasma clusterin levels and cognitive decline was observed in AD patients ( r = 0.23; p ≤0.05). In CSF, but not in plasma, clusterin levels correlated with Tau and pTau in all groups. Conclusion: Elevated plasma clusterin levels in MCI confer an increased risk for progression to AD, and more rapid cognitive decline. We speculate that clusterin levels in CSF may reflect its involvement in the earliest neurodegenerative processes associated with AD pathology. Whereas neither clusterin levels in CSF nor in plasma had diagnostic value, plasma clusterin levels may serve as a prognostic marker for AD.

Amyloid-β (Aβ)-oligomers are neurotoxic isoforms of Aβ and are a potential diagnostic biomarker for Alzheimer's disease (AD). 1) Analyze the potential of Aβ-oligomer concentrations in cerebrospinal fluid (CSF) to diagnose and predict progression to AD in a large clinical study sample. 2) Monitor Aβ-oligomer concentrations over-time, both in early and advanced stages of AD. 3) Examine the relation between Aβ-oligomer levels in CSF and cognitive functioning. 24 non-demented, 61 mild cognitive impairment (MCI), and 64 AD patients who underwent lumbar puncture and cognitive testing at baseline and follow-up were selected from the memory clinic based Amsterdam Dementia Cohort. CSF samples were analyzed for standard AD-biomarkers and Aβ-oligomer levels using a validated in-house Aβ-oligomer specific enzyme-linked immunosorbent assay. Aβ-oligomer levels were analyzed as indicators of disease progression (follow-up AD diagnosis) and cognitive decline, respectively. Patient groups did not differ in Aβ-oligomer concentrations at baseline or follow-up. Baseline CSF Aβ-oligomer levels were similar in MCI patients that develop AD as in stable MCI patients. MCI and AD patients showed an annual decrease in Aβ-oligomer levels of 9.4% and 6.8%, respectively. A decrease in Aβ-oligomer levels over time was strongly associated with more severe cognitive decline in AD patients. Despite the limited diagnostic potential of Aβ-oligomer levels in CSF to differentiate between patient groups, and between MCI-AD and MCI-stable patients, changes in CSF Aβ-oligomer levels were related to cognitive decline. Therefore, CSF Aβ-oligomers may aid in the selection of patients with a more aggressive disease course.

Summary: Objective: A possible association between serum 25‐hydroxyvitamin D and testosterone levels has been reported; however, contradictory results have emerged.Design: To investigate a causal link between vitamin D and testosterone status, we studied the effect of vitamin D supplementation on serum testosterone concentrations in three independent intervention studies including male patients with heart failure (study 1), male nursing home residents (study 2) and male non‐Western immigrants in the Netherlands (study 3).Methods: In study 1, 92 subjects were randomized to either vitamin D (2000 IU cholecalciferol daily) or control. Blood was drawn at baseline, after 3 and 6 weeks. In study 2, 49 vitamin D deficient subjects received either vitamin D (600 IU daily) or placebo. Blood was drawn at baseline, after 8 and 16 weeks. In study 3, 43 vitamin D deficient subjects received either vitamin D (1200 IU daily) or placebo. Blood was drawn at baseline, after 8 and 16 weeks. Serum 25‐hydroxyvitamin D levels were measured using LC‐MS/MS or radioimmunoassay. Testosterone levels were measured using a 2nd generation immunoassay.Results: Serum 25‐hydroxyvitamin D levels significantly increased in all treatment groups (median increase of 27, 30 and 36 nmol/l in studies 1, 2 3, respectively) but not in the control groups. The documented increase in 25‐hydroxyvitamin D levels, however, did not affect mean testosterone concentrations at the end of the study (median increase of 0, 0·5 and 0 nmol/l in studies 1, 2 and 3, respectively).Conclusions: In this post hoc analysis of three small clinical trials of limited duration in men with normal baseline testosterone concentrations, vitamin D supplementation was not associated with an increase in circulating testosterone concentrations.