1.
Desmoplakin as a Potential Candidate for Cerebrospinal Fluid Marker to Rule Out 14-3-3 False Positive Rates in Sporadic Creutzfeldt-Jakob Disease Differential Diagnosis.
Source
National Reference Center for TSE Surveillance, Department of Neurology, Medical Center Georg August University, Göttingen, Germany.
Abstract
Background: The detection of a 14-3-3 elevated level in cerebrospinal fluid (CSF) is a part of the diagnostic criteria for probable sporadic Creutzfeldt-Jakob disease (sCJD), as defined by the WHO. However, some pathological conditions associated with acute neuronal damage may result in a positive 14-3-3 test and thereby reduce test specificity in sCJD. Objective: Desmoplakin has been previously identified as up-regulated CSF protein in sCJD and these studies aimed to investigate its diagnostic utility and compare it with two known CSF markers, 14-3-3 and tau. Methods and Results: We tested CSF levels of 14-3-3, tau and desmoplakin in 58 sCJD patients and 81 control patients including 45 cases with an elevated 14-3-3 level due to other disease than sCJD. We detected an elevated CSF level of desmoplakin in 78% of the sCJD patients, while 14-3-3 (88%) and tau (91%) showed a higher positive rate. However, the false positive rate of newly tested desmoplakin was significantly lower in comparison to 14-3-3 and tau, and it accounted for only 11% versus 56% and 35%, respectively. Further reduction of false positive rates was achieved by combination of elevated tau level with a positive desmoplakin test. Moreover, in the non-sCJD group, desmoplakin level did not correlate with the level of both above-mentioned CSF markers, whereas a clear correlation was observed in the sCJD group. Conclusion: Desmoplakin showed a low positive rate accompanied by a very low false positive rate. Thus, we conclude that desmoplakin is a promising candidate for supportive CSF marker to rule out 14-3-3 false positive cases in sCJD differential diagnosis.
Copyright © 2011 S. Karger AG, Basel.
Phosphorus Dendrimers Affect Alzheimer's (Aβ1-28) Peptide and MAP-Tau Protein Aggregation.
Abstract
Alzheimer's disease (AD) is characterized by pathological aggregation of β-amyloid peptides and MAP-Tau protein. β-amyloid (Aβ) is a peptide responsible for extracellular Alzheimer's plaque formation. Intracellular MAP-Tau aggregates appear as a result of hyperphosphorylation of this cytoskeletal protein. Small, oligomeric forms of Aβ are intermediate products that appear before the amyloid plaques are formed. These forms are believed to be most neurotoxic. Dendrimers are highly branched polymers, which may find an application in regulation of amyloid fibril formation. Several biophysical and biochemical methods, like circular dichroism (CD), fluorescence intensity of thioflavin T and thioflavin S, transmission electron microscopy, spectrofluorimetry (measuring quenching of intrinsic peptide fluorescence) and MTT-cytotoxicity assay, were applied to characterize interactions of cationic phosphorus-containing dendrimers of generation 3 and generation 4 (CPDG3, CPDG4) with the fragment of amyloid peptide (Aβ1-28) and MAP-Tau protein. We have demonstrated that CPDs are able to affect β-amyloid and MAP-Tau aggregation processes. A neuro-2a cell line (N2a) was used to test cytotoxicity of formed fibrils and intermediate products during the Aβ1-28 aggregation. It has been shown that CPDs might have a beneficial effect by reducing the system toxicity. Presented results suggest that phosphorus dendrimers may be used in the future as agents regulating the fibrilization processes in Alzheimer's disease.
A Blood-Based Screening Tool for Alzheimer's Disease That Spans Serum and Plasma: Findings from TARC and ADNI.
Source
Department of Neurology, F. Marie Hall Institute for Rural and Community Health, Garrison Institute on Aging, Texas Tech University Health Sciences Center, Lubbock, Texas, United States of America.
Abstract
CONTEXT:
There is no rapid and cost effective tool that can be implemented as a front-line screening tool for Alzheimer's disease (AD) at the population level.
OBJECTIVE:
To generate and cross-validate a blood-based screener for AD that yields acceptable accuracy across both serum and plasma.
DESIGN, SETTING, PARTICIPANTS:
Analysis of serum biomarker proteins were conducted on 197 Alzheimer's disease (AD) participants and 199 control participants from the Texas Alzheimer's Research Consortium (TARC) with further analysis conducted on plasma proteins from 112 AD and 52 control participants from the Alzheimer's Disease Neuroimaging Initiative (ADNI). The full algorithm was derived from a biomarker risk score, clinical lab (glucose, triglycerides, total cholesterol, homocysteine), and demographic (age, gender, education, APOE*E4 status) data.
MAJOR OUTCOME MEASURES:
Alzheimer's disease.
RESULTS:
11 proteins met our criteria and were utilized for the biomarker risk score. The random forest (RF) biomarker risk score from the TARC serum samples (training set) yielded adequate accuracy in the ADNI plasma sample (training set) (AUC = 0.70, sensitivity (SN) = 0.54 and specificity (SP) = 0.78), which was below that obtained from ADNI cerebral spinal fluid (CSF) analyses (t-tau/Aβ ratio AUC = 0.92). However, the full algorithm yielded excellent accuracy (AUC = 0.88, SN = 0.75, and SP = 0.91). The likelihood ratio of having AD based on a positive test finding (LR+) = 7.03 (SE = 1.17; 95% CI = 4.49-14.47), the likelihood ratio of not having AD based on the algorithm (LR-) = 3.55 (SE = 1.15; 2.22-5.71), and the odds ratio of AD were calculated in the ADNI cohort (OR) = 28.70 (1.55; 95% CI = 11.86-69.47).
CONCLUSIONS:
It is possible to create a blood-based screening algorithm that works across both serum and plasma that provides a comparable screening accuracy to that obtained from CSF analyses.
- PMID:
- 22163278
- [PubMed - as supplied by publisher]
- PMCID: PMC3233542
Correlation of Levels of Neuronal and Glial Markers with Radiological Measures of Infarct Volume in Ischaemic Stroke: A Systematic Review.
Source
Division of Clinical Neurosciences, Bramwell Dott Building, Western General Hospital, Edinburgh, UK.
Abstract
Background: A blood test that quantified the extent of brain damage following ischaemic stroke might be a useful surrogate outcome measure in trials of acute stroke treatments. Measures of neuronal and glial damage, such as neuron-specific enolase (NSE), glial fibrillary acidic protein, tau-protein, myelin-basic protein and S100-β are potential candidate biomarkers. Aim: We systematically reviewed the relevant literature to find studies that correlated blood levels of neuronal and glial damage markers with imaging measures of infarct volume. Methods: We identified studies with a comprehensive search of databases and the reference lists of relevant studies. We included studies that: (1) measured the highest level, or area under the curve (AUC) over time of markers of cerebral damage, (2) calculated infarct volume, and (3) correlated the two measures. Results: Seventeen studies met the criteria for the systematic review. There were sufficient data to provide summary estimates for S100-β and NSE. The peak level and AUC over time of both markers correlated with subacute infarct volume. Measurements of S100-β later than 24 h after stroke were better correlated with subacute infarct size than earlier measurements. However, scan times varied, and none was later than 8 days after stroke. Conclusion: Peak and AUC levels of NSE and S100-β levels correlated with subacute infarct volume. Correlations of S100-β with infarct volume were stronger when measured after 24 h than closer to admission. Exploratory studies within clinical trials are necessary before blood markers of cerebral tissue damage can be recommended as surrogate endpoints.
Copyright © 2011 S. Karger AG, Basel.
Impact of chronic Helicobacter pylori infection on Alzheimer's disease: preliminary results.
Source
Institut National de la Sante et de la Recherche Medicale U853, Bordeaux, France; Univ. Bordeaux, Laboratoire de Bactériologie, F-33000 Bordeaux, France; Pôle de gérontologie clinique, CHU Hôpitaux de Bordeaux, Bordeaux, France.
Abstract
Recent case-control studies reported an association between H. pylori infection and Alzheimer's disease (AD). Our aim was to compare cognitive impairment, neuroinflammation, and cerebrovascular lesion load in a group of AD patients according to their H. pylori status. For the 53 AD patients included, we assessed: clinical data (vascular comorbidities and cognitive assessment), biological data (especially fibrinogen, homocysteine levels, apolipoprotein E4 genotype; cerebrospinal fluid [CSF] total tau protein [Tau], phospho-tau(181) protein [pTau(181)]), and amyloid beta peptide levels, serum/CSF-cytokines (interleukin [IL]-1β, IL-6, IL-8, tumor necrosis factor [TNF]-α) and pepsinogen I/pepsinogen II (PgI/PgII) ratio, and cerebrovascular lesion load (magnetic resonance imaging [MRI] fluid-attenuated inversion recovery [FLAIR] with the Fazekas and Schmidt scale). H. pylori infection was diagnosed by enzyme-linked immunosorbent assay (ELISA) and immunoblot test. H. pylori infection was associated with a decreased Mini Mental State Examination (MMS) (p = 0.024), and higher CSF pTau(181) (p = 0.014) and tau (p = 0.021) levels. A decreased PgI/II ratio (i.e., an increased gastric atrophy) was associated with the infection (p = 0.005). Homocysteine levels were positively correlated to Fazekas score (r = 0.34; p = 0.032) and to H. pylori immunoglobulin (Ig)G levels (r = 0.44; p = 0.001). Higher CSF cytokine levels (IL-8, p = 0.003; TNF-α, p = 0.019) were associated with the infection, but systemic inflammation results were controversial. Finally, in multivariate analysis, a lower MMSE score (odds ratio [OR], 0.83 [0.72-0.97]; p = 0.017), plasma IL-1β level (OR, 0.31 [0.11-0.87]; p = 0.025), an increased gastric atrophy, i.e., a lower PgI/PgII ratio (OR, 0.63 [0.43-0.93]; p = 0.020) were still associated with the infection. AD patients infected by H. pylori tended to be more cognitively impaired. Studies are needed to attest to the impact of H. pylori infection on AD course, especially on cerebrovascular lesions and neuroinflammation.
Copyright © 2011 Elsevier Inc. All rights reserved.
Long-term oral intake of aluminium or zinc does not accelerate Alzheimer pathology in AβPP and AβPP/tau transgenic mice.
Source
Department of Dementia and Higher Brain Function, Tokyo Metropolitan Institute of Medical Science Department of Human Life Science, Showa Women's University Department of Diagnosis, Prevention and Treatment of Dementia, Graduate School of Juntendo University, Tokyo Department of Pharmacology, International University of Health and Welfare, Tochigi, Japan.
Abstract
Whether or not the oral intake of metals such as aluminium (Al) and zinc (Zn) is a risk for Alzheimer's disease (AD) has been a matter of controversy. Lack of AD pathology in patients with Al encephalopathy indicates Al does not cause AD. On the other hand, some epidemiological studies have suggested high Al increases the occurrence of AD. Our purpose is to test if high Al in drinking water is a risk factor for AD. We administered Al and Zn in drinking water to Tg2576, a transgenic mouse model for amyloid β-protein (Aβ) deposition with the Aβ precursor protein (AβPP) mutations (K670N/M671L), and Tg2576/tau(P301L), a model for Aβ and tau deposition. Deionized water was given to the control Tg2576 and Tg2576/tau. After administration for 4-10 months of approximately 100 mg/kg body weight Al or Zn per day, we were not able to find by quantitative immunohistochemical analyses differences in the deposition of Aβ and taubetween the treated and untreated groups. Nor did the Al or Zn treatment affect the amount of soluble Aβ and Aβ*56, an Aβ oligomer, measured by ELISA or immunoblot. The oral intake of excess Al or Zn does not accelerate AD pathology in the transgenic mouse models for Aβ and tau accumulation. Such results do not seem to support the notion that excessive oral intake of Al or Zn is a risk factor for AD.
© 2011 Japanese Society of Neuropathology.
Tau elevations in the brain extracellular space correlate with reduced amyloid-β levels and predict adverse clinical outcomes after severe traumatic brain injury.
Source
1 Department of Anaesthesia and Intensive Care, Fondazione IRCCS Cà Granda-Ospedale Maggiore Policlinico, Milan University, Milano 20100, Italy.
Abstract
Axonal injury is believed to be a major determinant of adverse outcomes following traumatic brain injury. However, it has been difficult to assess acutely the severity of axonal injury in human traumatic brain injury patients. We hypothesized that microdialysis-based measurements of the brain extracellular fluid levels of tau and neurofilament light chain, two low molecular weight axonal proteins, could be helpful in this regard. To test this hypothesis, 100 kDa cut-off microdialysis catheters were placed in 16 patients with severe traumatic brain injury at two neurological/neurosurgical intensive care units. Tau levels in the microdialysis samples were highest early and fell over time in all patients. Initial tau levels were >3-fold higher in patients with microdialysis catheters placed in pericontusional regions than in patients in whom catheters were placed in normal-appearing right frontal lobe tissue (P = 0.005). Tau levels and neurofilament light-chain levels were positively correlated (r = 0.6, P = 0.013). Neurofilament light-chain levels were also higher in patients with pericontusional catheters (P = 0.04). Interestingly, initial tau levels were inversely correlated with initial amyloid-β levels measured in the same samples (r = -0.87, P = 0.000023). This could be due to reduced synaptic activity in areas with substantial axonal injury, as amyloid-β release is closely coupled with synaptic activity. Importantly, high initial taulevels correlated with worse clinical outcomes, as assessed using the Glasgow Outcome Scale 6 months after injury (r = -0.6, P = 0.018). Taken together, our data add support for the hypothesis that axonal injury may be related to long-term impairments following traumatic brain injury. Microdialysis-based measurement of tau levels in the brain extracellular space may be a useful way to assess the severity of axonal injury acutely in the intensive care unit. Further studies with larger numbers of patients will be required to assess the reproducibility of these findings and to determine whether this approach provides added value when combined with clinical and radiological information.
Recent rodent models for Alzheimer's disease: clinical implications and basicresearch.
Source
Department of Pharmacology, University of New South Wales, Sydney, NSW, 2052, Australia.
Abstract
Alzheimer's disease (AD) is the most common origin of dementia in the elderly. Although the cause of AD remains unknown, several factors have been identified that appear to play a critical role in the development of this debilitating disorder. In particular, amyloid precursor protein (APP), tau hyperphosphorylation, and the secretase enzymes, have become the focal point of recent research. Over the last two decades, several transgenic and non-transgenic animal models have been developed to elucidate the mechanistic aspects of AD and to validate potential therapeutic targets. Transgenic rodent models over-expressing human β-amyloid precursor protein (β-APP) and mutant forms of tau have become precious tools to study and understand the pathogenesis of AD at the molecular, cellular and behavioural levels, and to test new therapeutic agents. Nevertheless, none of the transgenic models of AD recapitulate fully all of the pathological features of the disease. Octodon degu, a South American rodent has been recently found to spontaneously develop neuropathological signs of AD in old age. This review aims to address the limitations and clinical relevance of transgenic rodent models in AD, and to highlight the potential for O. degu as a natural model for the study of AD neuropathology.
An experimental rat model of sporadic Alzheimer's disease and rescue of cognitive impairment with a neurotrophic peptide.
Source
Department of Neurochemistry, New York State Institute for Basic Research in Developmental Disabilities, 1050 Forest Hill Road, Staten Island, NY, 10314, USA.
Abstract
Alzheimer's disease (AD) is multifactorial and, to date, no single cause of the sporadic form of this disease, which accounts for over 99% of the cases, has been established. In AD brain, protein phosphatase-2A (PP2A) activity is known to be compromised due to the cleavage and translocation of its potent endogenous inhibitor, I (2) (PP2A) , from the neuronal nucleus to the cytoplasm. Here, we show that adeno-associated virus vector-induced expression of the N-terminal I(2NTF) and C-terminal I(2CTF) halves of I (2) (PP2A) , also called SET, in brain reproduced key features of AD in Wistar rats. The I(2NTF-CTF) rats showed a decrease in brain PP2A activity, abnormal hyperphosphorylation and aggregation of tau, a loss of neuronal plasticity and impairment in spatial reference and working memories. To testwhether early pharmacologic intervention with a neurotrophic molecule could rescue neurodegeneration and behavioral deficits, 2.5-month-old I(2NTF-CTF) rats and control littermates were treated for 40 days with Peptide 6, an 11-mer peptide corresponding to an active region of the ciliary neurotrophic factor. Peripheral administration of Peptide 6 rescued neurodegeneration and cognitive deficit in I(2NTF-CTF) animals by increasing dentate gyrus neurogenesis and mRNA level of brain derived neurotrophic factor. Moreover, Peptide 6-treated I(2NTF-CTF) rats showed a significant increase in dendritic and synaptic density as reflected by increased expression of synapsin I, synaptophysin and MAP2, especially in the pyramidal neurons of CA1 and CA3 of the hippocampus.
Protein binding in patients with late-life depression.
Source
Department of Psychiatry, University of Illinois at Chicago, USA. akumar@psych.uic.edu
Abstract
CONTEXT:
Depression has been identified as a risk factor and a prodrome of dementia. Common neurobiological mechanisms may underlie this clinical and phenomenologic overlap.
OBJECTIVE:
To examine and compare protein (amyloid and tau) binding in critical brain regions in patients diagnosed as having late-life major depressive disorder (MDD) and healthy control individuals using 2-(1-{6-[(2-[(18)F]fluoroethyl)(methyl)-amino]-2-naphthyl}ethylidene) malononitrile ([(18)F]FDDNP) positron emission tomography.
DESIGN:
A cross-section neuroimaging study using positron emission tomography.
SETTING:
University of California, Los Angeles. Patients Our samples comprised 20 patients diagnosed as having MDD and 19 healthy control individuals of comparable age, sex, and educational level. Main Outcome Measure Relative distribution volume in regions of interest was used as the measure of [(18)F]FDDNP binding in all study participants.
RESULTS:
When compared with controls, [(18)F]FDDNP binding was significantly higher overall and in the posterior cingulate and lateral temporal regions in the MDD group.
CONCLUSIONS:
These findings suggest that neuronal injury associated with higher protein load in critical brain regions might provide a mechanism in the pathophysiologic manifestation of MDD in late life and have implications for the therapeutics of depression in elderly individuals.
GSPE interferes with tau aggregation in vivo: implication for treating tauopathy.
Source
Department of Neurology, Mount Sinai School of Medicine, New York, NY, USA; Alzheimer Disease Research Unit, CIEN Foundation, Queen Sofia Foundation, Madrid, Spain.
Abstract
Tauopathies are characterized by progressive neurodegeneration caused by intracellular accumulation of hyperphosphorylated tau protein aggregates in the brain. The present study was designed to test whether a grape seed polyphenolic extract (GSPE) previously shown to inhibit tau protein aggregation in vitro could benefit tau-mediated neuropathology and behavior deficits in JNPL3 transgenic mice expressing a human tau protein containing the P301L mutation. Nine-month-old JNPL3 mice were treated with GSPE delivered through their drinking water for 6 months. We found that GSPE treatment significantly reduced the number of motor neurons immunoreactive for hyperphosphorylated and conformationally-modified tau in the ventral horns of the spinal cord identified using AT100, PHF-1, AT8, and Alz50tau antibodies. This coincided with a drastically reduced level of hyperphosphorylated and sarcosyl-insoluble tau in spinal cord fractions. Furthermore, the reduction of tau pathology was accompanied by an improvement in the motor function assessed by a wire hang test. Collectively, our results suggest that GSPE can interfere with tau-mediated neurodegenerative mechanisms and ameliorate neurodegenerative phenotype in an animal model of tauopathy. Our studies support further evaluation of GSPE for preventing and/or treating of tauopathies in humans.
Copyright © 2011 Elsevier Inc. All rights reserved.
Vector-mediated expression of erythropoietin improves functional outcome after cervical spinal cord contusion injury.
Source
Department of Neurology, University of Michigan and VA Ann Arbor Healthcare System, Ann Arbor, MI, USA.
Abstract
We evaluated the therapeutic effect of erythropoietin (EPO) delivered by direct injection of a nonreplicating herpes simplex virus (HSV)-based vector coding for EPO (vEPO) in a model of cervical hemicord contusion at C7. At 1 h after spinal cord injury (SCI), either vEPO or control vector carrying a reporter gene (vC) was injected into the cord above and below the lesion. Animals injected with vEPO showed a statistically significant improvement in the ipsilateral forelimb function, as measured by open-field evaluation of motor performance, forelimb reaching in the cylinder test and misplacement in grid walk. This correlated with preservation of gray matter in the area of the lesion. There was also mild but significant improvement of hindlimb motor function measured by Basso-Beattie-Bresnahan score and computerized gait analysis in vEPO compared with control vector-injected animals. Microtubule-associated protein tau, phosphorylated and nonphosphorylated neurofilament protein and the synaptic proteins synaptophysin and PSD-95 were all significantly increased in the spinal cord of vEPO-treated animals compared with control vector-injected animals. These data suggest that gene transfer of EPO after cervical SCI by minimizing the injury size and enhancing tissue sparing preserves large-caliber axons and promotes synaptogenesis.Gene Therapy advance online publication, 3 November 2011; doi:10.1038/gt.2011.166.
Chronic Mild Stress Accelerates the Onset and Progression of the Alzheimer's Disease Phenotype in Tg2576 Mice.
Source
Division of Neurosciences, CIMA, University of Navarra, Pamplona, Spain Department of Anatomy, Faculty of Medicine, University of Navarra, Pamplona, Spain.
Abstract
The etiology of the more common (sporadic) forms of Alzheimer's disease (AD) remains unknown, although age is the most important risk factor. Nevertheless, interactions between environmental risk factors and genetic background may also influence the onset and progression of sporadic AD. Chronic stress, associated with altered memory and other neurological processes, is thought to influence the pathogenesis of AD. Hence, we evaluated the effect of unpredictable and consecutive chronic mild stressors on the onset of an AD-related pathology in the Tg2576 mouse line that overexpresses the human amyloid-β protein precursor with the Swedish mutation (hAβPPSwe). Two months after exposure to chronic mild stress, 4 month-old animals that normally display no pathological features of AD, not only expressed pathological markers but also experienced cognitive dysfunction in the Morris water maze test. These findings suggest that chronic mild stress accelerates the onset of cognitive impairment and produces an increase in hippocampal amyloid-β and phospho-tau levels on a background of AD susceptibility.
Does physical activity reduce risk for Alzheimer's disease through interaction with the stress neuroendocrine system?
Source
Physical Activity and Sports Sciences, University of Alicante , 03690 San Vicente del Raspeig - Alicante , Spain.
Abstract
Lack of physical activity (PA) is a risk factor for Alzheimer's disease (AD), and PA interventions are believed to provide an effective non-pharmacological approach for attenuating the symptoms of this disease. However, the mechanism of action of these positive effects is currently unknown. It is possible that the benefits may be at least partially mediated by the effects on the neuroendocrine stress system. Chronic stress can lead to dysfunction of the hypothalamic-pituitary-adrenal (HPA) axis, leading to aberrant basal and circadian patterns of cortisol secretion and a cascade of negative downstream events. These factors have been linked not only to reduced cognitive function but also increased levels of amyloid-β plaques and protein tau "tangles" (the neuropathological hallmarks of AD) in the non-demented mouse models of this disease. However, there is evidence that PA can have restorative effects on the stress neuroendocrine system and related risk factors relevant to AD. We explore the possibility that PA can positively impact upon AD by restoring normative HPA axis function, with consequent downstream effects upon underlying neuropathology and associated cognitive function. We conclude with suggestions for future research to test this hypothesis in patients with AD.
Predicting MCI outcome with clinically available MRI and CSF biomarkers.
Source
Department of Radiology, University of California, San Diego, La Jolla, CA 92093-0841, USA.
Abstract
OBJECTIVE:
To determine the ability of clinically available volumetric MRI (vMRI) and CSF biomarkers, alone or in combination with a quantitative learning measure, to predict conversion to Alzheimer disease (AD) in patients with mild cognitive impairment (MCI).
METHODS:
We stratified 192 MCI participants into positive and negative risk groups on the basis of 1) degree of learning impairment on the Rey Auditory Verbal Learning Test; 2) medial temporal atrophy, quantified from Food and Drug Administration-approved software for automated vMRI analysis; and 3) CSF biomarker levels(.) We also stratified participants based on combinations of risk factors. We computed Cox proportional hazards models, controlling for age, to assess 3-year risk of converting to AD as a function of risk group and used Kaplan-Meier analyses to determine median survival times.
RESULTS:
When risk factors were examined separately, individuals testing positive showed significantly higher risk of converting to AD than individuals testing negative (hazard ratios [HR] 1.8-4.1). The joint presence of any 2 risk factors substantially increased risk, with the combination of greater learning impairment and increased atrophy associated with highest risk (HR 29.0): 85% of patients with both risk factors converted to AD within 3 years, vs 5% of those with neither. The presence of medial temporal atrophy was associated with shortest median dementia-free survival (15 months).
CONCLUSIONS:
Incorporating quantitative assessment of learning ability along with vMRI or CSF biomarkers in the clinical workup of MCI can provide critical information on risk of imminent conversion to AD.
- PMID:
- 21998317
- [PubMed - indexed for MEDLINE]
- PMCID: PMC3198979
- [Available on 2012/10/25]
Protein stability: a single recorded mutation aids in predicting the effects of other mutations in the same amino acid site.
Source
Department of Biochemistry and Molecular Biology, Tel-Aviv University, Ramat Aviv 69978, Israel.
Abstract
MOTIVATION:
Accurate prediction of protein stability is important for understanding the molecular underpinnings of diseases and for the design of new proteins. We introduce a novel approach for the prediction of changes in proteinstability that arise from a single-site amino acid substitution; the approach uses available data on mutations occurring in the same position and in other positions. Our algorithm, named Pro-Maya (Protein Mutant stAbilitY Analyzer), combines a collaborative filtering baseline model, Random Forests regression and a diverse set of features. Pro-Maya predicts the stability free energy difference of mutant versus wild type, denoted as ΔΔG.
RESULTS:
We evaluated our algorithm extensively using cross-validation on two previously utilized datasets of single amino acid mutations and a (third) validation set. The results indicate that using known ΔΔG values of mutations at the query position improves the accuracy of ΔΔG predictions for other mutations in that position. The accuracy of our predictions in such cases significantly surpasses that of similar methods, achieving, e.g. a Pearson's correlation coefficient of 0.79 and a root mean square error of 0.96 on the validation set. Because Pro-Maya uses a diverse set of features, including predictions using two other methods, it also performs slightly better than other methods in the absence of additional experimental data on the query positions.
AVAILABILITY:
Pro-Maya is freely available via web server at http://bental.tau.ac.il/ProMaya.
CONTACT:
nirb@tauex.tau.ac.il; wolf@cs.tau.ac.il
SUPPLEMENTARY INFORMATION:
Supplementary data are available at Bioinformatics online.
Role of family history for Alzheimer biomarker abnormalities in the adult children study.
Source
Charles F. and Joanne Knight Alzheimer's Disease Research Center, Washington University School of Medicine, St Louis, Missouri, USA. chengjie@wubios.wustl.edu
Abstract
OBJECTIVE:
To assess whether family history (FH) of Alzheimer disease (AD) alone influences AD biomarker abnormalities.
DESIGN:
Adult Children Study.
SETTING:
Washington University's Charles F. and Joanne Knight Alzheimer's Disease Research Center.
PARTICIPANTS:
A total of 269 cognitively normal middle- to older-aged individuals with and without an FH for AD.
MAIN OUTCOME MEASURES:
Clinical and cognitive measures, magnetic resonance imaging-based brain volumes, diffusion tensor imaging-based white matter microstructure, cerebrospinal fluid biomarkers, and molecular imaging of cerebral fibrillar amyloid with positron emission tomography using the [(11)C] benzothiazole tracer, Pittsburgh compound B.
RESULTS:
A positive FH for AD was associated with an age-related decrease of cerebrospinal fluid Aβ42; the ε4 allele of apolipoprotein E (APOE4) did not alter this effect. Age-adjusted cerebrospinal fluid Aβ42 was decreased for individuals with APOE4 compared with the level for those without, and the decrease was larger for individuals with a positive FH compared with the decrease for those without. The variation of cerebrospinal fluid tau and Pittsburgh compound B mean cortical binding potential increased by age. For individuals younger than 55, an age-related increase in mean cortical binding potential was associated with APOE4 but not FH. For individuals older than 55, a positive FH and a positive APOE4 implied the fastest age-related increase in mean cortical binding potential. A positive FH was associated with decreased fractional anisotropy from diffusion tensor imaging in the genu and splenium of the corpus callosum.
CONCLUSION:
Independent of APOE4, FH is associated with age-related change of several cerebrospinal fluid, Pittsburgh compound B, and diffusion tensor imaging biomarkers in cognitively normal middle- to older-aged individuals, suggesting that non- APOE susceptibility genes for AD influence AD biomarkers.
Pharmacokinetics of felodipine extended-release tablets in healthy Taiwanese subjects: a retrospective review.
Source
College of Pharmacy, Taipei Medical University, Taipei, Taiwan.
Abstract
The objective of this study was to investigate the pharmacokinetics of felodipine (CAS 72509-76-3) in healthy male Taiwanese subjects. This is a retrospective review of five felodipine pharmacokinetic studies completed in Taiwan. A total of 100 evaluable healthy Taiwanese males were enrolled in these studies. The subjects received 5 mg (n = 80) or 10 mg (n = 20) of Plendil (felodipine extended-release tablets; felodipine ER) once daily for 6 days. The mean +/- SD t(max,ss,) CG(max,ss) and AUG(tau) of dose normalized to 10 mg felodipine was 3.32 +/- 1.33 h, 13.12 +/- 5.34 nmol/L and 136.33 +/- 63.18 nmol x h/L, respectively. By using Kolmogorov-Smirnov's test and probit plots, the results indicated that the frequency distribution of AUC/dose, C(min)/dose and CL/F was bimodal. Compared to data from the literature, the mean C(max,ss) and AUG(tau) of 5 mg felodipine in healthy young Taiwanese subjects were similar to or slightly lower than data from Swedish, Danish, Turkish and Canadian studies in healthy young subjects who received 10 mg felodipine. Comparable C(max) values and approximately 30% lower AUC values were observed when comparing the 5 mg Taiwanese data to data in healthy elderly German subjects who also received 5 mg felodipine. Taiwanese subjects might have lower CYP3A4 activity to metabolize felodipine, which is similar to the phenomenon observed with nifedipine.
- PMID:
- 21950148
- [PubMed - indexed for MEDLINE]
Predictive value of microtubule associated proteins tau and stathmin in patients with nonmuscle invasive bladder cancer receiving adjuvant intravesical taxane therapy.
Source
Department of Urology, Columbia University College of Physicians and Surgeons, Columbia University, New York, New York 10032, USA.
Abstract
PURPOSE:
After encouraging results from 2 clinical trials performed at our institution to test intravesical taxane based chemotherapy for bacillus Calmette-Guérin refractory, nonmuscle invasive bladder cancer we designed a study to identify molecular markers linked to the optimal response to such treatment modality.
MATERIALS AND METHODS:
Included in the institutional review board approved study were 32 patients with nonmuscle invasive, bacillus Calmette-Guérin refractory bladder cancer who received intravesical taxane chemotherapy, that is docetaxel or nanoparticle albumin-bound paclitaxel. Immunophenotype analysis on tissue samples obtained before intravesical taxane therapy was done using a panel of molecular markers, including Ki-67, p53, and the microtubule associated proteins tau and stathmin.
RESULTS:
Increased total tau (cytoplasmic and nuclear) and stathmin expression before intravesical taxane therapy was significantly associated with decreased recurrence-free survival (p <0.0001 and 0.007, respectively). A tau positive phenotype was an independent prognostic factor for recurrence-free survival on multivariate analysis (HR 15.66, 95% CI 2.68-91.71, p = 0.002). Neither the proliferation index assessed by Ki-67 expression nor p53 status was significantly associated with recurrence-free survival.
CONCLUSIONS:
Assessment of tau and stathmin protein expression should be considered to select patients before intravesical taxane based chemotherapy for nonmuscle invasive, bacillus Calmette-Guérin refractory bladder cancer since those who have tumors with low tau/stathmin protein expression show a better response to therapy.
Copyright © 2011 American Urological Association Education and Research, Inc. Published by Elsevier Inc. All rights reserved.
The Effects of Regularly Spaced Glutamine Substitutions on Alpha-Helical Peptide Structures. A DFT/ONIOM Study.
Source
Department of Chemistry, City University of New York - Hunter College and the Graduate School, 695 Park Avenue, New York NY 10065.
Abstract
The side-chains of the residues of glutamine (Q) and asparagine (N) contain amide groups. These can H-bond to each other in patterns similar to those of the backbone amides in α-helices. We show that mutating multiple Q's for alanines (A's) in a polyalanine helix stabilizes the helical structure, while similar mutations with multiple N's do not. We suggest that modification of peptides by incorporating Q's in such positions can make more robust helices that can be used totest the effects of secondary structures in biochemical experiments linked to proteins with variable structures such astau and α-synuclein.
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