FTIR Spectroscopy and Blood-Derived Extracellular Vesicles Duo in Alzheimer's Disease.

Background: Alzheimer's disease (AD) diagnosis is difficult, and new accurate tools based on peripheral biofluids are urgently needed. Extracellular vesicles (EVs) emerged as a valuable source of biomarker profiles for AD, since their cargo is disease-specific and these can be easily isolated from easily accessible biofluids, as blood. Fourier Transform Infrared (FTIR) spectroscopy can be employed to analyze EVs and obtain the spectroscopic profiles from different regions of the spectra, simultaneously characterizing carbohydrates, nucleic acids, proteins, and lipids. Objective: The aim of this study was to identify blood-derived EVs (bdEVs) spectroscopic signatures with AD discriminatory potential. Methods: Herein, FTIR spectra of bdEVs from two biofluids (serum and plasma) and distinct sets of Controls and AD cases were acquired, and EVs' spectra analyzed. Results: Analysis of bdEVs second derivative peaks area revealed differences between Controls and AD cases in distinct spectra regions, assigned to carbohydrates and nucleic acids, amides, and lipids. Conclusions: EVs' spectroscopic profiles presented AD discriminatory value, supporting the use of bdEVs combined with FTIR as a screening or complementary tool for AD diagnosis.

Phosphoproteome Microarray Analysis of Extracellular Particles as a Tool to Explore Novel Biomarker Candidates for Alzheimer's Disease.

Phosphorylation plays a key role in Alzheimer's disease (AD) pathogenesis, impacting distinct processes such as amyloid-beta (Aß) peptide production and tau phosphorylation. Impaired phosphorylation events contribute to senile plaques and neurofibrillary tangles' formation, two major histopathological hallmarks of AD. Blood-derived extracellular particles (bdEP) can represent a disease-related source of phosphobiomarker candidates, and hence, in this pilot study, bdEP of Control and AD cases were analyzed by a targeted phosphoproteomics approach using a high-density microarray that featured at least 1145 pan-specific and 913 phosphosite-specific antibodies. This approach, innovatively applied to bdEP, allowed the identification of 150 proteins whose expression levels and/or phosphorylation patterns were significantly altered across AD cases. Gene Ontology enrichment and Reactome pathway analysis unraveled potentially relevant molecular targets and disease-associated pathways, and protein-protein interaction networks were constructed to highlight key targets. The discriminatory value of both the total proteome and the phosphoproteome was evaluated by univariate and multivariate approaches. This pilot experiment supports that bdEP are enriched in phosphotargets relevant in an AD context, holding value as peripheral biomarker candidates for disease diagnosis.

Diagnostic performance of automated plasma amyloid-ß assays combined with pre-analytical immunoprecipitation.

BACKGROUND: Measurements of the amyloid-ß (Aß) 42/40 ratio in blood plasma may support the early diagnosis of Alzheimer's disease and aid in the selection of suitable participants in clinical trials. Here, we compared the diagnostic performance of fully automated prototype plasma Aß42/40 assays with and without pre-analytical sample workup by immunoprecipitation. METHODS: A pre-selected clinical sample comprising 42 subjects with normal and 38 subjects with low cerebrospinal fluid (CSF) Aß42/40 ratios was studied. The plasma Aß42/40 ratios were determined with fully automated prototype Elecsys® immunoassays (Roche Diagnostics GmbH, Penzberg, Germany) by direct measurements in EDTA plasma or after pre-analytical Aß immunoprecipitation. The diagnostic performance for the detection of abnormal CSF Aß42/40 was analyzed by receiver operating characteristic (ROC) analysis. In an additional post hoc analysis, a biomarker-supported clinical diagnosis was used as a second endpoint. RESULTS: Pre-analytical immunoprecipitation resulted in a significant increase in the area under the ROC curve (AUC) from 0.73 to 0.88 (p = 0.01547) for identifying subjects with abnormal CSF Aß42/40. A similar improvement in the diagnostic performance by pre-analytical immunoprecipitation was also observed when a biomarker-supported clinical diagnosis was used as a second endpoint (AUC increase from 0.77 to 0.92, p = 0.01576). CONCLUSIONS: Our preliminary observations indicate that pre-analytical Aß immunoprecipitation can improve the diagnostic performance of plasma Aß assays for detecting brain amyloid pathology. The findings may aid in the further development of blood-based immunoassays for Alzheimer's disease ultimately suitable for screening and routine use.

Identification of risk factors for delirium, cognitive decline, and dementia after cardiac surgery (FINDERI-find delirium risk factors): a study protocol of a prospective observational study.

BACKGROUND: Postoperative delirium is a common complication of cardiac surgery associated with higher morbidity, longer hospital stay, risk of cognitive decline, dementia, and mortality. Geriatric patients, patients undergoing cardiac surgery, and intensive care patients are at a high risk of developing postoperative delirium. Gold standard assessments or biomarkers to predict risk factors for delirium, cognitive decline, and dementia in patients undergoing cardiac surgery are not yet available. METHODS: The FINDERI trial (FINd DElirium RIsk factors) is a prospective, single-center, observational study. In total, 500 patients aged ≥ 50 years undergoing cardiac surgery at the Department of Cardiovascular and Thoracic Surgery of the University of Göttingen Medical Center will be recruited. Our primary aim is to validate a delirium risk assessment in context of cardiac surgery. Our secondary aims are to identify specific preoperative and perioperative factors associated with delirium, cognitive decline, and accelerated dementia after cardiac surgery, and to identify blood-based biomarkers that predict the incidence of postoperative delirium, cognitive decline, or dementia in patients undergoing cardiac surgery. DISCUSSION: This prospective, observational study might help to identify patients at high risk for delirium prior to cardiac surgery, and to identify important biological mechanisms by which cardiac surgery is associated with delirium. The predictive value of a delirium screening questionnaire in cardiac surgery might be revealed. Finally, the identification of specific blood biomarkers might help to predict delirium, cognitive decline, and dementia in patients undergoing cardiac surgery. TRIAL REGISTRATION: Ethics approval for this study was obtained from the IRB of the University of Göttingen Medical Center. The investigators registered this study in the German Clinical Trials Register (DRKS; https://www.drks.de ) (DRKS00025095) on April 19th, 2021.

Sudden paraparesis due to spinal cord ischemia with initial contrast enhancement of the cauda equina and time-delayed owl-eyes sign on follow-up MR imaging: a case report.

We report on a case of a 52-year-old male with sudden paraparesis. The initial MRI showed contrast enhancement of the conus medullaris and the complete cauda equina. Follow-up MRI revealed a spinal ischemia in the anterior portion of the spinal cord. Only a few reports with similar findings have been published. We suggest that contrast enhancement of the conus medullaris and descending nerve roots can be a potential first indicator of a spinal cord ischemia.

Post-mortem serum concentrations of GFAP correlate with agony time but do not indicate a primary cerebral cause of death.

BACKGROUND AND PURPOSE: The astroglial protein GFAP is a blood biomarker indicative of intracerebral hemorrhage in patients with acute stroke. Due to its brain specificity and the necessity of brain damage for its detectability in blood, we hypothesized that GFAP could be an interesting marker in cases with primary cerebral cause of death, e.g., traumatic brain injury. METHODS: All corpses scheduled for an autopsy in the Frankfurt Department of Forensic medicine within a 15-month period were included in the study. Cases with a known history of brain disease in the 3 months before death were excluded. During autopsy, blood was collected and GFAP serum levels were determined using a commercially available ELISA. The autopsy protocols were reviewed for the presence of a primary cerebral or a primary non-cerebral cause of death. Agony time was also determined. RESULTS: A total of 129 autopsy cases were included. GFAP concentrations did not differ between cerebral (median 0.96 µg/l, IQR 5.03) and non-cerebral causes of death (1.21 µg/l, 3.58). GFAP levels were found to be unaffected by hemolysis or post-mortem interval. GFAP levels were found to be increased in cases with prolonged agony times (median 1.76 µg/l [IQR 4.70]) compared to short (0.58 µg/l [0.58]; p<0.001) and ultra-short agony times (0.21 µg/l [0.12]; p = 0.002). CONCLUSION: Post-mortem GFAP serum concentrations correlate with agony time and might therefore be useful for the evaluation of the severity of brain damage in prolonged death. Elevated GFAP serum levels do not indicate a primary cerebral cause of death.