Optimized RT-qPCR and a novel normalization method for validating circulating miRNA biomarkers in ageing-related diseases.

Circulating miRNAs have potential as minimally invasive biomarkers for diagnosing various diseases, including ageing-related disorders such as Alzheimer's disease (AD). However, the lack of standardization in the common analysis method, RT-qPCR, and specifically in the normalization step, has resulted in inconsistent data across studies, hindering miRNA clinical implementation as well as basic research. To address this issue, this study proposes an optimized protocol for key steps in miRNA profiling, which incorporates absorbance-based haemolysis detection for assessing sample quality, double spike-in controls for miRNA isolation and reverse transcription, and the use of 7 stable normalizers verified in an aging population, including healthy subjects and individuals at different stages of Alzheimer's disease (140 subjects). The stability of these 7 normalizers was demonstrated using our novel method called BestmiRNorm for identifying optimal normalizers. BestmiRNorm, developed utilizing the Python programming language, enables the assessment of up to 11 potential normalizers. The standardized application of this optimized RT-qPCR protocol and the recommended normalizers are crucial for the development of miRNAs as biomarkers for AD and other ageing-related diseases in clinical diagnostics and basic research.

TREM2 Gene Compound Heterozygosity in Neurodegenerative Disorders.

BACKGROUND: Homozygous variants of the TREM2 and TYROBP genes have been shown to be causative for multiple bone cysts and neurodegeneration leading to progressive dementia (NHD, Nasu-Hakola disease). OBJECTIVE: To determine if biallelic variants of these genes and/or oligogenic inheritance could be responsible for a wider spectrum of neurodegenerative conditions. METHODS: We analyzed 52 genes associated with neurodegenerative disorders using targeted next generation sequencing in a selected group of 29 patients (n = 14 Alzheimer's disease, n = 8 frontotemporal dementia, n = 7 amyotrophic lateral sclerosis) carrying diverse already determined rare variants in exon 2 of TREM2. Molecular modeling was used to get an insight into the potential effects of the mutation. RESULTS: We identified a novel mutation c.401_406delinsTCTAT; p.(Asp134Valfs*55) in exon 3 of TREM2 in an Alzheimer's disease patient also carrying the p.Arg62His TREM2 variant. Molecular modeling revealed that the identified mutation prevents anchoring of the TREM2 protein in the membrane, leaving the core of the Ig-like domain intact. CONCLUSION: Our results expand the spectrum of neurodegenerative diseases, where the carriers of biallelic mutations in TREM2 have been described for Alzheimer's disease, and highlight the impact of variant burden in other genes on phenotypic heterogeneity.

Metabolism and the Effect of Animal-Derived Oxysterols in the Diet on the Development of Alzheimer's Disease.

BACKGROUND: The rapid worldwide increase in the incidence of Alzheimer's disease is associated with changing nutrition patterns. Recently, some articles have highlighted the link between Alzheimer's disease and dietary cholesterol. It was found that elevated levels of some of its fractions in the brain and circulation affect metabolism. SUMMARY: Previous studies have considered the relationship between Alzheimer's disease and oxidized cholesterol molecules in the brain. To date, there are limited data available on the relationship between oxidized cholesterol in the brain and Alzheimer's disease. There is a link between a diet high in cholesterol and its oxidized forms, leading to hypercholesterolemia, which is one of significant risk factors of dementia, and Alzheimer's disease. Oxidized cholesterol can be absorbed in the small intestine and cross the blood-brain barrier, leading to increased inflammation and endogenous oxidative process. Animal-origin foods are sources of oxidized cholesterol, with cholesterol oxidation beginning already after slaughter and occurring during storage and processing. KEY MESSAGES: High-heat food preparation and storage of cooked products in the refrigerator followed by subsequent heating may significantly increase the amount of oxidized cholesterol products. Therefore, a diet low in cholesterol oxidation products and high in plants with antioxidative properties seems to be most preventable and should be implemented as early as possible.

Are Executive Functions Deficits in Early-Onset Chronic Schizophrenia More Severe than in Adult-Onset Chronic Schizophrenia?

Objective: The research on the age of schizophrenia onset and cognitive impairments leads to contradictory conclusions. It is still unknown whether neurocognitive deficits in early-onset schizophrenia (EOS) are more intense than adulthood-onset schizophrenia (AOS). The study aimed to examine specific aspects of the executive functions of chronic outpatients with different ages of schizophrenia onset. Method: Two clinical groups (EOS and AOS) consisted of 60 chronic outpatients with schizophrenia recruited from the community-based support system. The executive functions were measured with the Wisconsin Card Sorting Test (WCST), Trail Making Test A&B (TMT A&B), verbal fluency task (VFT), and the N-back test. Obtained results were compared to control groups consisting of 40 healthy subjects, matched with age, sex, and years of education, respectively. Results: There were no differences in various aspects of executive dysfunctions between EOS and AOS outpatients. The outpatients in general, had lower scores than healthy controls regardless of their age of symptom onset. The most important finding suggests that some cognitive domains (visual working memory and processing speed) in presented schizophrenia patients were similar to those in healthy controls.Despite the demographic differences, both clinical groups present the same level of executive functioning. In addition, similar to the healthy participants, the outpatients had no problems in working memory and processing speed. Conclusions: These observations suggest that EOS might not be associated with more severe cognitive deterioration. Moreover, the stabilization or improvement of their functioning might be linked with long-term psycho-social rehabilitation and modern pharmacotherapy.

Changes in the Hormonal Profile of Athletes following a Combat Sports Performance.

RESULTS: Following fighting, the adrenaline concentration was significantly higher in all athletes, most markedly in K (p < 0.001). Baseline cortisol and BDNF levels did not differ among the groups and rose significantly in all the groups after the performance. Baseline testosterone concentration was slightly higher in K than in JSW and rose in all the groups to reach similar levels; the increase in T was significantly higher than in K. CONCLUSIONS: Despite substantial differences in the characteristics of the combat sports investigated, including the type of physical effort and the required balance between restraint and aggression, the performance in each of them gives rise to similar hormonal changes with a possible exception of karate showing higher stress hormone levels.

Abnormalities of DYRK1A-Cytoskeleton Complexes in the Blood Cells as Potential Biomarkers of Alzheimer's Disease.

BACKGROUND: DYRK1A is implicated in mental retardation and Alzheimer's disease (AD) dementia of Down syndrome (DS) individuals. The protein is associated with cytoskeleton and altered expression has been shown to impair the cytoskeletal network via dosage effect. OBJECTIVE: Our original observations of marked reduction of cytoskeletal proteins associated with DYRK1A in brains and lymphoblastoid cell lines from DS and AD prompted an investigation whether cytoskeleton abnormalities could potentially be used as biomarkers of AD. METHODS: Our assay relied on quantification of co-immunoprecipitated cytoskeletal proteins with DYRK1A (co-IP assay) and analysis of the profile of G- and F-actin fractions obtained by high-speed centrifugations (spin-down assay). RESULTS: In co-IP assay, both DS and AD samples displayed reduced abundance of associated cytoskeletal proteins. In spin-down assay, G-actin fractions of controls displayed two closely spaced bands of actin in SDS-PAGE; while in AD and DS, only the upper band of the doublet was present. In both assays, alterations of actin cytoskeleton were present in DS, sporadic and familial AD cases, and in asymptomatic persons who later progressed to confirmed AD, but not in non-AD donors. In blind testing involving six AD and six controls, the above tests positively identified ten cases. Analysis of blood samples revealed the diversity of mild cognitive impairment (MCI) cases regarding the presence of the AD biomarker allowing distinction between likely prodromal AD and non-AD MCI cases. CONCLUSIONS: Both brain tissue and lymphocytes from DS and AD displayed similar semi-quantitative and qualitative alterations of actin cytoskeleton. Their specificity for AD-type dementia and the presence before clinical onset of the disease make them suitable biomarker candidates for early and definite diagnosis of AD. The presence of alterations in peripheral tissue points to systemic underlying mechanisms and suggests that early dysfunction of cytoskeleton may be a predisposing factor in the development of AD.

Association of serotoninergic pathway gene variants with elite athletic status in the Polish population.

Genetic factors are known to influence sport performance. The aim of the present study was to assess genetic variants in genes coding for proteins potentially modulating activity of brain emotion centres in a group of 621 elite athletes (212 endurance, 183 power and 226 combat athletes) and 672 sedentary controls. Ten statistically significant variants were identified in genes encoding elements of serotoninergic, catecholaminergic and hypothalamic-pituitary-adrenal systems in different sport groups. Of those the rs860573 variant in the FEV gene coding for transcription factor exclusively expressed in neurons of the central serotonin system is the only one whose frequency significantly differentiates all the groups of athletes studied, regardless of discipline, from the controls (p = 0.000026). Our results support the hypothesis that genetic variants potentially affecting mental processes and emotions, particularly in the serotonergic pathway, also influence the predispositions to athletic performance.

The Erlangen Score Algorithm in the diagnosis and prediction of the progression from subjective cognitive decline and mild cognitive impairment to Alzheimer-type dementia.

The evaluation of cerebrospinal fluid (CSF) biomarkers for Alzheimer's disease (AD) (ß-amyloid, t-tau, p-tau) can be used to estimate the risk of developing dementia in patients at the pre-clinical stages of AD, i.e. subjective cognitive decline (SCD) and mild cognitive impairment (MCI). Erlangen Score Algorithm allows interpretation of CSF biomarker concentrations and is cut-off value independent. The aim of this study was to establish if this algorithm can be applied for routine diagnostic testing in clinical and preclinical subjects and has prognostic value. We analysed 217 patients from the memory clinic with the diagnosis of SCD (n = 31), MCI (n = 104), and AD (n = 82) with clinical follow-up amounting to 14.33 months (SD = 6.82). It was found that the highest Erlangen Score dominated in the AD group and was the rarest in the SCD group. In the group of patients with progression of symptoms during our period of observation, the AD pathology was confirmed in 93.75% of cases. Among the non-progressing subjects (n = 119) the algorithm indicated the risk of developing AD as possible in 40.34% and probable in 15.97% of cases. To conclude, the Erlangen Score Algorithm is a useful tool to determinate the risk of developing AD before the onset of dementia or to confirm the AD diagnosis. It is extremely valuable in preclinical stages of AD for planning purposes and early intervention as well as for future clinical trials.

Hypermethylation of TRIM59 and KLF14 Influences Cell Death Signaling in Familial Alzheimer's Disease.

Epigenetic mechanisms play an important role in the development and progression of various neurodegenerative diseases. Abnormal methylation of numerous genes responsible for regulation of transcription, DNA replication, and apoptosis has been linked to Alzheimer's disease (AD) pathology. We have recently performed whole transcriptome profiling of familial early-onset Alzheimer's disease (fEOAD) patient-derived fibroblasts. On this basis, we demonstrated a strong dysregulation of cell cycle checkpoints and DNA damage response (DDR) in both fibroblasts and reprogrammed neurons. Here, we show that the aging-correlated hypermethylation of KLF14 and TRIM59 genes associates with abnormalities in DNA repair and cell cycle control in fEOAD. Based on the resulting transcriptome networks, we found that the hypermethylation of KLF14 might be associated with epigenetic regulation of the chromatin organization and mRNA processing followed by hypermethylation of TRIM59 likely associated with the G2/M cell cycle phase and p53 role in DNA repair with BRCA1 protein as the key player. We propose that the hypermethylation of KLF14 could constitute a superior epigenetic mechanism for TRIM59 hypermethylation. The methylation status of both genes affects genome stability and might contribute to proapoptotic signaling in AD. Since this study combines data obtained from various tissues from AD patients, it reinforces the view that the genetic methylation status in the blood may be a valuable predictor of molecular processes occurring in affected tissues. Further research is necessary to define a detailed role of TRIM59 and KLF4 in neurodegeneration of neurons.

TREM2 variants in neurodegenerative disorders in the Polish population. Homozygosity and compound heterozygosity in FTD patients.

Activation of the TREM2 receptor on microglia stimulates phagocytosis and decreases the microglial proinflammatory response. Mutations in exon 2 of the TREM2 gene have been reported to be associated with various neurodegenerative diseases characterized by chronic inflammation. The aim of our study was to evaluate exon 2 of TREM2 gene variants as a putative genetic risk factor for Alzheimer's disease (AD), frontotemporal dementia (FTD), and amyotrophic lateral sclerosis (ALS) in the Polish population. The results were interpreted using previously published data, especially highlighting differences in the prevalence of the variants among Caucasian subpopulations across different geographic regions. The DNA sequence of exon 2 of TREM2 was analyzed in 811 subjects (274 AD, 135 FTD, 194 ALS patients, and 208 neurologically healthy controls). Nine heterozygous variants were detected, including two novel ones: p.G29 = and c.41-2_3insA, found respectively in a control and an ALS patient. Additionally, we identified one homozygous and two compound heterozygous FTD patients. We confirm previous data that homozygous and compound heterozygous TREM2 mutations can be causative for FTD.

Overactive BRCA1 Affects Presenilin 1 in Induced Pluripotent Stem Cell-Derived Neurons in Alzheimer's Disease.

The BRCA1 protein, one of the major players responsible for DNA damage response has recently been linked to Alzheimer's disease (AD). Using primary fibroblasts and neurons reprogrammed from induced pluripotent stem cells (iPSC) derived from familial AD (FAD) patients, we studied the role of the BRCA1 protein underlying molecular neurodegeneration. By whole-transcriptome approach, we have found wide range of disturbances in cell cycle and DNA damage response in FAD fibroblasts. This was manifested by significantly increased content of BRCA1 phosphorylated on Ser1524 and abnormal ubiquitination and subcellular distribution of presenilin 1 (PS1). Accordingly, the iPSC-derived FAD neurons showed increased content of BRCA1(Ser1524) colocalized with degraded PS1, accompanied by an enhanced immunostaining pattern of amyloid-ß. Finally, overactivation of BRCA1 was followed by an increased content of Cdc25C phosphorylated on Ser216, likely triggering cell cycle re-entry in FAD neurons. This study suggests that overactivated BRCA1 could both influence PS1 turnover leading to amyloid-ß pathology and promote cell cycle re-entry-driven cell death of postmitotic neurons in AD.

Association between Cerebrospinal Fluid Biomarkers for Alzheimer's Disease, APOE Genotypes and Auditory Verbal Learning Task in Subjective Cognitive Decline, Mild Cognitive Impairment, and Alzheimer's Disease.

In the course of Alzheimer's disease (AD), early pathological changes in the brain start decades before any clinical manifestation. The concentration levels of AD cerebrospinal fluid (CSF) biomarkers, such as amyloid-ß1-42 (Aß1-42), total tau (T-tau), and phosphorylated tau (P-tau), may reflect a cerebral pathology facilitating an early diagnosis of the disease and predicting a cognitive deterioration. The aim of this study was to estimate the prevalence of AD CSF biomarkers in those individuals with a subjective cognitive decline (SCD), a mild cognitive impairment (MCI), and Alzheimer's dementia (AD-D), together with the relationships between the biomarkers, an APOE ɛ4 presence, and a verbal episodic memory performance. We included 252 patients from the memory clinic with a diagnosis of SCD (n = 85), MCI (n = 87), and AD-D (n = 80). A verbal episodic memory performance level was assessed and was based on a delayed recall trial from the 10-word list of an auditory verbal learning task (AVLT). We found that the patients with more severe cognitive impairments had significantly lower levels of Aß1-42 and higher levels of T-tau and P-tau. This pattern was also typical for the APOE ɛ4 carriers, who had lower levels of Aß1-42 than the noncarriers in the AD-D and MCI groups. The levels of T-tau and P-tau were significantly higher in the APOE ɛ4 carriers than in the noncarriers, but only in the MCI patients. The AVLT performance in the whole study samples was predicted by age, Aß1-42, and the T-tau CSF biomarkers, but not by the APOE genotyping.

Combined use of biochemical and volumetric biomarkers to assess the risk of conversion of mild cognitive impairment to Alzheimer's disease.

INTRODUCTION: The aim of our study was to evaluate the usefulness of several biomarkers in predicting the conversion of mild cognitive impairment (MCI) to Alzheimer's disease (AD): ß-amyloid and tau proteins in cerebrospinal fluid and the volumetric evaluation of brain structures including the hippocampus in magnetic resonance imaging (MRI). MATERIAL AND METHODS: MRI of the brain with the volumetric assessment of hippocampus, entorhinal cortex, posterior cingulate gyrus, parahippocampal gyrus, superior, medial and inferior temporal gyri was performed in 40 patients diagnosed with mild cognitive impairment. Each patient had a lumbar puncture to evaluate ß-amyloid and tau protein (total and phosphorylated) levels in the cerebrospinal fluid. The observation period was 2 years. RESULTS: Amongst 40 patients with MCI, 9 (22.5%) converted to AD within 2 years of observation. Discriminant analysis was conducted and sensitivity for MCI conversion to AD on the basis of volumetric measurements was 88.9% and specificity 90.3%; on the basis of ß-amyloid and total tau, sensitivity was 77.8% and specificity 83.9%. The combined use of the results of volumetric measurements with the results of proteins in the cerebrospinal fluid did not increase the sensitivity (88.9%) but increased specificity to 96.8% and the percentage of correct classification to 95%.

Predicting the conversion of mild cognitive impairment to Alzheimer's disease based on the volumetric measurements of the selected brain structures in magnetic resonance imaging.

INTRODUCTION: Mild cognitive impairment (MCI) is defined as abnormal cognitive state, but does not meet the criteria for the diagnosis of dementia. According to the new guidelines Alzheimer's disease (AD) involves not only dementia's phase but also predementia phase which is asymptomatic and pathological process in the brain is already present. For this reason it is very important to determine the suitability of markers which should be positive before onset of the first symptoms. One of these biomarkers is a structural magnetic resonance imaging with hippocampal volumetric assessment. The aim of this study was to investigate the usefulness of structural brain magnetic resonance imaging with volumetric assessment of the hippocampus and entorhinal cortex, posterior cingulate gyrus, parahippocampal gyrus, temporal gyri: superior, medial and inferior, to predict the conversion of MCI to AD. MATERIAL AND METHODS: Magnetic resonance imaging of brain was performed at the baseline visit in 101 patients diagnosed with MCI. Clinic follow-ups were scheduled after 6.12 and 24 months. RESULTS: Amongst 101 patients with MCI, 17 (16.8%) converted into AD within two years of observation. All measured volumes were lower in converters than non-converters. Discriminant analysis was conducted and sensitivity for MCI conversion to AD was 64.7%, specificity 96.4%. 91% of patients were correctly classified (converter or non-converter). CONCLUSIONS: Volumetric measurements may help clinicians to predict MCI conversion to AD but due to low sensitivity it cannot be use separately. The study group requires further observation.

Writing in Richardson variant of progressive supranuclear palsy in comparison to progressive non-fluent aphasia.

BACKGROUND: The overlap between progressive supranuclear palsy (PSP) and progressive non-fluent aphasia (PNFA) is being increasingly recognized. In this paper descriptive writing in patients with Richardson syndrome of progressive supranuclear palsy (PSP-RS) is compared to writing samples from patients with PNFA. METHODS: Twenty-seven patients participated in the study: 17 with the clinical diagnosis of PSP-RS and 10 with PNFA. Untimed written picture description was administered during neuropsychological assessment and subsequently scored by two raters blinded to the clinical diagnosis. Lexical and syntactic content, as well as writing errors (e.g. omission and perseverative errors) were analyzed. RESULTS: In patients with PSP-RS both letter and diacritic mark omission errors were very frequent. Micrographia was present in 8 cases (47%) in PSP-RS group and in one case (10%) with PNFA. Perseverative errors did not differentiate between the groups. CONCLUSIONS: As omission errors predominate in writing of patients with PSP-RS, writing seems to be compromised mainly because of oculomotor deficits, that may alter visual feedback while writing.

Is descriptive writing useful in the differential diagnosis of logopenic variant of primary progressive aphasia, Alzheimer's disease and mild cognitive impairment?

Current classification of primary progressive aphasia (PPA) encompasses three variants: non-fluent (nfvPPA), semantic (svPPA) and logopenic (lvPPA). Previously lvPPA was regarded as aphasic form of Alzheimer's disease (AD). However, not all patients with lvPPA phenotype present with AD pathology. Despite abundant literature on differentiation of lvPPA from svPPA and nfvPPA, studies comparing lvPPA with AD and mild cognitive impairment (MCI) are scarce. This study aimed at analyzing written descriptive output in lvPPA, AD and MCI. Thirty-five patients participated in the study: 9 with lvPPA, 13 with AD and 13 with MCI. Most aspects of writing performance were comparable in three groups. However, letter insertion errors appeared in 44% patients with lvPPA, while they were absent in AD and MCI. Patients with lvPPA used more verbs than patients with AD. Writing profile may complement other neuropsychological assessment results in the differential diagnosis of lvPPA. Letter insertion errors and frequent verb use may raise a query of lvPPA.

Neuropsychological assessment and differential diagnosis in young-onset dementias.

Although Alzheimer's disease is the most common cause of dementia in the elderly, there are several conditions (ie, frontotemporal dementia or Huntington's disease) associated with a relatively earlier onset. This article provides arguments in favor of a comprehensive neuropsychological assessment in the differential diagnosis of young-onset dementia, as episodic memory impairment is not observed early in the course of most types of young-onset dementia that predominantly affect the domains of behavior, executive, language, and/or motor function.

PsbS is required for systemic acquired acclimation and post-excess-light-stress optimization of chlorophyll fluorescence decay times in Arabidopsis.

Systemic acquired acclimation (SAA) is an important light acclimatory mechanism that depends on the global adjustments of non-photochemical quenching and chloroplast retrograde signaling. As the exact regulation of these processes is not known, we measured time-resolved fluorescence of chlorophyll a in Arabidopsis thaliana leaves exposed to excess light, in leaves undergoing SAA, and in leaves after excess light episode. We compare the behavior induced in wild-type plants with null mutant of non-photochemical quenching (npq4-1). The wild type rosettes exhibit a small reduction of fluorescence decay times in leaves directly exposed to excess light and in leaves undergoing SAA in ambient low light. However in npq4-1 exposition to excess light results in much faster fluorescence decay, which is insensitive to excitation power. At the same time npq4-1 leaves undergoing SAA displayed intermediate fluorescence decay. The npq4-1 plants also lost the ability to optimize florescence decay, and thus chlorophyll a dynamics up to 2 h after excess light episode. The fluorescence decay dynamics in both WT and npq4-1 can be described by a set of 3 maximum decay times. Based on the results, we concluded that functional PsbS is required for optimization of absorbed photon fate and optimal light acclimatory responses such as SAA or after excess light stress.

Agraphia in patients with frontotemporal dementia and parkinsonism linked to chromosome 17 with P301L MAPT mutation: dysexecutive, aphasic, apraxic or spatial phenomenon?

OBJECTIVES: Patients with frontotemporal dementia and parkinsonism linked to chromosome 17 (FTDP-17) may be agraphic. The study aimed at characterizing agraphia in individuals with a P301L MAPT mutation. METHODS: Two pairs of siblings with FTDP-17 were longitudinally examined for agraphia in relation to language and cognitive deficits. RESULTS: All patients presented with dysexecutive agraphia. In addition, in the first pair of siblings one sibling demonstrated spatial agraphia with less pronounced allographic agraphia and the other sibling had aphasic agraphia. Aphasic agraphia was also present in one sibling from the second pair. CONCLUSION: Agraphia associated with FTDP-17 is very heterogeneous.

[Visual impairment in posterior cortical atrophy--visual variant of Alzheimer's disease in the ophthalmic practice]. / Zaburzenia widzenia w zaniku korowym tylnym--wariant wzrokowy choroby Alzheimera w praktyce okulistycznej.

Posterior cortical atrophy, also known as visual variant of Alzheimer's disease, is a rare dementia syndrome characterized by the predominant visuospatial functional deficit. The ophthalmologist is usually the first specialist consultant the patient is referred to with such complaints as: reading difficulty, face recognition problems, feeling of visual field restriction, difficulty perceiving more than one object at a time, difficulty grabbing objects under visual control, recognizing familiar surroundings, watching television or driving a car. Posterior cortical atrophy is one of early-onset (below 65 years of age) dementia syndromes and is most often associated with Alzheimer's pathology. Visual impairment is due to the disturbance of one or two visual pathways in the brain (dorsal--analyzing the stimulus localization, ventral--enabling the stimulus recognition) and subsequent atrophy of parietal and/or occipital lobe. The article presents the clinical characteristics and diagnostic criteria of posterior cortical atrophyas well as abnormal findings of the extended ophtalmic examination and methods utilised in differential diagnosis of cortical vision deficits. Early diagnosis of posterior cortical atrophy can be ensured by the close cooperation between the ophtalomogist and a neurologist specializing in the diagnosis of neurodegenerative diseases.