Fatigue behavior of freestanding nickel-molybdenum-tungsten thin films with high-density planar faults.

This research addresses the fatigue behavior of freestanding nickel-molybdenum-tungsten (Ni-Mo-W) thin films with high-density planar faults. The as-deposited Ni-Mo-W thin films demonstrate an unprecedented fatigue life, withstanding over a million cycles at a Goodman stress amplitude (Sa,Goodman) of 2190 MPa - nearly 80% of the tensile strength. The texture, columnar grain width, planar fault configuration (spacing and orientation), and tensile strength were unchanged after annealing at 500 °C for 24 hours, and the film endured over 2 × 105 cycles at Sa,Goodman of 1050 MPa. The fatigue life of annealed Ni-Mo-W thin films is comparable to those of nanocrystalline Ni-based alloys, but has deteriorated significantly compared to that of the as-deposited films. The high fatigue strength of Ni-Mo-W thin films is ascribed to extremely dense planar faults suppressing fatigue crack initiation, and planar fault-dislocation interaction and grain boundary plasticity are proposed as mechanisms responsible for the fatigue failure. Provisionally the latter is a more convincing account of the experimental results, in which changes in the grain boundary characteristics after annealing cause higher susceptibility to stress concentration during cyclic loading. The fatigue behavior revealed in this work consolidates the thermal and mechanical reliability of Ni-Mo-W thin films for potential nano-structural applications.

Distinct spatiotemporal patterns of cortical thinning in Alzheimer's disease-type cognitive impairment and subcortical vascular cognitive impairment.

Previous studies on Alzheimer's disease-type cognitive impairment (ADCI) and subcortical vascular cognitive impairment (SVCI) has rarely explored spatiotemporal heterogeneity. This study aims to identify distinct spatiotemporal cortical atrophy patterns in ADCI and SVCI. 1,338 participants (713 ADCI, 208 SVCI, and 417 cognitively unimpaired elders) underwent brain magnetic resonance imaging (MRI), amyloid positron emission tomography, and neuropsychological tests. Using MRI, this study measures cortical thickness in five brain regions (medial temporal, inferior temporal, posterior medial parietal, lateral parietal, and frontal areas) and utilizes the Subtype and Stage Inference (SuStaIn) model to predict the most probable subtype and stage for each participant. SuStaIn identifies two distinct cortical thinning patterns in ADCI (medial temporal: 65.8%, diffuse: 34.2%) and SVCI (frontotemporal: 47.1%, parietal: 52.9%) patients. The medial temporal subtype of ADCI shows a faster decline in attention, visuospatial, visual memory, and frontal/executive domains than the diffuse subtype (p-value < 0.01). However, there are no significant differences in longitudinal cognitive outcomes between the two subtypes of SVCI. Our study provides valuable insights into the distinct spatiotemporal patterns of cortical thinning in patients with ADCI and SVCI, suggesting the potential for individualized therapeutic and preventive strategies to improve clinical outcomes.

Association of Glycemic Variability With Imaging Markers of Vascular Burden, ß-Amyloid, Brain Atrophy, and Cognitive Impairment.

BACKGROUND AND OBJECTIVE: We aimed to investigate the association between glycemic variability (GV) and neuroimaging markers of white matter hyperintensities (WMH), beta-amyloid (Aß), brain atrophy, and cognitive impairment. METHODS: This was a retrospective cohort study that included participants without dementia from a memory clinic. They all had Aß PET, brain MRI, and standardized neuropsychological tests and had fasting glucose (FG) levels tested more than twice during the study period. We defined GV as the intraindividual visit-to-visit variability in FG levels. Multivariable linear regression and logistic regression were used to identify whether GV was associated with the presence of severe WMH and Aß uptake with DM, mean FG levels, age, sex, hypertension, and presence of APOE4 allele as covariates. Mediation analyses were used to investigate the mediating effect of WMH and Aß uptake on the relationship between GV and brain atrophy and cognition. RESULTS: Among the 688 participants, the mean age was 72.2 years, and the proportion of female participants was 51.9%. Increase in GV was predictive of the presence of severe WMH (coefficient [95% CI] 1.032 [1.012-1.054]; p = 0.002) and increased Aß uptake (1.005 [1.001-1.008]; p = 0.007). Both WMH and increased Aß uptake partially mediated the relationship between GV and frontal-executive dysfunction (GV → WMH → frontal-executive; direct effect, -0.319 [-0.557 to -0.080]; indirect effect, -0.050 [-0.091 to -0.008]) and memory dysfunction (GV → Aß â†’ memory; direct effect, -0.182 [-0.338 to -0.026]; indirect effect, -0.067 [-0.119 to -0.015]), respectively. In addition, increased Aß uptake completely mediated the relationship between GV and hippocampal volume (indirect effect, -1.091 [-2.078 to -0.103]) and partially mediated the relationship between GV and parietal thickness (direct effect, -0.00101 [-0.00185 to -0.00016]; indirect effect, -0.00016 [-0.00032 to -0.000002]). DISCUSSION: Our findings suggest that increased GV is related to vascular and Alzheimer risk factors and neurodegenerative markers, which in turn leads to subsequent cognitive impairment. Furthermore, GV can be considered a potentially modifiable risk factor for dementia prevention.

Clinical outcomes of increased focal amyloid uptake in individuals with subthreshold global amyloid levels.

Background: Although the standardized uptake value ratio (SUVR) method is objective and simple, cut-off optimization using global SUVR values may not reflect focal increased uptake in the cerebrum. The present study investigated clinical and neuroimaging characteristics according to focally increased ß-amyloid (Aß) uptake and global Aß status. Methods: We recruited 968 participants with cognitive continuum. All participants underwent neuropsychological tests and 498 18F-florbetaben (FBB) amyloid positron emission tomography (PET) and 470 18F-flutemetamol (FMM) PET. Each PET scan was assessed in 10 regions (left and right frontal, lateral temporal, parietal, cingulate, and striatum) with focal-quantitative SUVR-based cutoff values for each region by using an iterative outlier approach. Results: A total of 62 (6.4%) subjects showed increased focal Aß uptake with subthreshold global Aß status [global (-) and focal (+) Aß group, G(-)F(+) group]. The G(-)F(+) group showed worse performance in memory impairment (p < 0.001), global cognition (p = 0.009), greater hippocampal atrophy (p = 0.045), compared to those in the G(-)F(-). Participants with widespread Aß involvement in the whole region [G(+)] showed worse neuropsychological (p < 0.001) and neuroimaging features (p < 0.001) than those with focal Aß involvement G(-)F(+). Conclusion: Our findings suggest that individuals show distinctive clinical outcomes according to focally increased Aß uptake and global Aß status. Thus, researchers and clinicians should pay more attention to focal increased Aß uptake in addition to global Aß status.

Motor Symptoms in Early- versus Late-Onset Alzheimer's Disease.

BACKGROUND: Age at onset was suggested as one possible risk factor for motor dysfunction in Alzheimer's disease (AD). OBJECTIVE: We investigated the association of motor symptoms with cognition or neurodegeneration in patients with AD, and whether this association differs by the age at onset. METHODS: We included 113 amyloid positive AD patients and divided them into early-onset AD (EOAD) and late-onset AD (LOAD), who underwent the Unified Parkinson's Disease Rating Scale (UPDRS)-Part III (=UPDRS) scoring, Mini-Mental State Examination (MMSE)/Clinical Deterioration Rating Sum-of-Boxes (CDR-SOB), and magnetic resonance image (MRI). Multiple linear regression was used to evaluate the association of UPDRS and MMSE/CDR-SOB or MRI neurodegeneration measures, and whether the association differs according to the group. RESULTS: The prevalence of motor symptoms and their severity did not differ between the groups. Lower MMSE (ß= -1.1, p < 0.001) and higher CDR-SOB (ß= 2.0, p < 0.001) were significantly associated with higher UPDRS. There was no interaction effect between MMSE/CDR-SOB and AD group on UPDRS. Global or all regional cortical thickness and putaminal volume were negatively associated with UPDRS score, but the interaction effect of neurodegeneration and AD group on UPDRS score was significant only in parietal lobe (p for interaction = 0.035), which showed EOAD to have a more pronounced association between parietal thinning and motor symptoms. CONCLUSION: Our study suggested that the severity of motor deterioration in AD is related to the severity of cognitive impairment itself rather than age at onset, and motor symptoms might occur through multiple mechanisms including cortical and subcortical atrophy.

Amyloid Positive Hydrocephalus: A Hydrocephalic Variant of Alzheimer's Disease?

BACKGROUND: Alzheimer's disease (AD) and normal pressure hydrocephalus (NPH) commonly coexist. OBJECTIVE: We aimed to characterize an overlapping syndrome of AD and NPH that presents with gait disturbance, ventriculomegaly on magnetic resonance imaging, and significant amyloid deposition on positron emission tomography (PET). METHODS: Of 114 patients who underwent cerebrospinal fluid (CSF) drainage for a possible diagnosis of NPH between 2015 and 2020 in Samsung Medical Center, we identified 24 patients (21.1%) with the NPH patients with amyloid deposition on PET, which we referred to as hydrocephalic AD in this study. We compared their clinical and imaging findings with those of 123 typical AD without hydrocephalic signs/symptoms. We also investigated the frequency and potential predictors of the tap test response in hydrocephalic AD. RESULTS: Evans' index was 0.36±0.03, and a disproportionately enlarged subarachnoid space was present in 54.2% of the hydrocephalic AD patients. The mean age (75.2±7.3 years) and the APOE4 frequency (68.2%) did not differ from those of AD controls. However, the hydrocephalic AD patients showed better memory and language performance, and a thinner cingulate cortex. About 42% of the hydrocephalic AD patients responded to the tap test, of whom seven underwent shunt surgery. Cognition did not improve, whereas gait improved after shunt surgery in all. CONCLUSION: Hydrocephalic AD has different neuropsychological and imaging characteristics from typical AD. Future studies are warranted to further investigate the effect of CSF removal on their clinical course and to elucidate the pathophysiological interaction between amyloid and NPH.

Prediction of tau accumulation in prodromal Alzheimer's disease using an ensemble machine learning approach.

We developed machine learning (ML) algorithms to predict abnormal tau accumulation among patients with prodromal AD. We recruited 64 patients with prodromal AD using the Alzheimer's Disease Neuroimaging Initiative (ADNI) dataset. Supervised ML approaches based on the random forest (RF) and a gradient boosting machine (GBM) were used. The GBM resulted in an AUC of 0.61 (95% confidence interval [CI] 0.579-0.647) with clinical data (age, sex, years of education) and a higher AUC of 0.817 (95% CI 0.804-0.830) with clinical and neuropsychological data. The highest AUC was 0.86 (95% CI 0.839-0.885) achieved with additional information such as cortical thickness in clinical data and neuropsychological results. Through the analysis of the impact order of the variables in each ML classifier, cortical thickness of the parietal lobe and occipital lobe and neuropsychological tests of memory domain were found to be more important features for each classifier. Our ML algorithms predicting tau burden may provide important information for the recruitment of participants in potential clinical trials of tau targeting therapies.

Strictly Lobar Microbleeds Reflect Amyloid Angiopathy Regardless of Cerebral and Cerebellar Compartments.

BACKGROUND AND PURPOSE: We aimed to determine whether lobar cerebellar microbleeds or concomitant lobar cerebellar and deep microbleeds, in the presence of lobar cerebral microbleeds, attribute to underlying advanced cerebral amyloid angiopathy pathology or hypertensive arteriopathy. METHODS: We categorized 71 patients with suspected cerebral amyloid angiopathy markers (regardless of the presence of deep and cerebellar microbleeds) into 4 groups according to microbleed distribution: L (strictly lobar cerebral, n=33), L/LCbll (strictly lobar cerebral and strictly lobar cerebellar microbleeds, n=13), L/Cbll/D (lobar, cerebellar, and deep microbleeds, n=17), and L/D (lobar and deep, n=8). We additionally categorized patients with cerebellar microbleeds into 2 groups according to dentate nucleus involvement: strictly lobar cerebellar (n=16) and dentate (n=14). We then compared clinical characteristics, Aß (amyloid-ß) positivity on PET (positron emission tomography), magnetic resonance imaging cerebral amyloid angiopathy markers, and cerebral small vessel disease burden among groups. RESULTS: The frequency of Aß positivity was higher in the L and L/LCbll groups (81.8% and 84.6%) than in the L/Cbll/D and L/D groups (37.5% and 29.4%; P<0.001), while lacune numbers were lower in the L and L/LCbll groups (1.7±3.3 and 1.7±2.6) than in the L/Cbll/D and L/D groups (8.0±10.3 and 13.4±17.7, P=0.001). The L/LCbll group had more lobar cerebral microbleeds than the L group (93.2±121.8 versus 38.0±40.8, P=0.047). The lobar cerebellar group had a higher Aß positivity (75% versus 28.6%, P=0.011) and lower lacune number (2.3±3.7 versus 8.6±1.2, P=0.041) than the dentate group. CONCLUSIONS: Strictly lobar cerebral and cerebellar microbleeds are related to cerebral amyloid angiopathy, whereas any combination of concurrent lobar and deep microbleeds suggest hypertensive angiopathy regardless of cerebral or cerebellar compartments.

Simultaneous and exact interval estimates for the contrast of two groups based on an extremely high dimensional variable: application to mass spec data.

MOTIVATION: Analysis of high-throughput proteomic/genomic data, in particular, surface-enhanced laser desorption/ionization time-of-flight mass spectrometry (SELDI-TOF MS) data and microarray data, has led to a multitude of techniques aimed at identifying potential biomarkers. Most of the statistical techniques for comparing two groups are based on qualitative measures such as P-value. A quantitative way such as interval estimation for the contrasts of two groups is more appealing. RESULTS: We have devised a simultaneous confidence bands method capable of detecting potential biomarkers, while controlling for overall confidence coverage level, in high-dimensional datasets that discriminate two treatment groups using a permutation scheme. For example, for the SELDI-TOF MS data, we deal with the entire spectrum simultaneously and construct (1 - alpha) confidence bands for the mean differences between groups. Furthermore, peaks were identified based on the maximal differences between the groups as determined by the confidence bands. The analysis method herein described gives both qualitative (P-value) and quantitative data (magnitude of difference). The Clinical Proteomics Programs Databank's ovarian cancer dataset and data from in-house samples containing known spiked-in proteins were analyzed. We were able to identify potential biomarkers similar to those described in previous analysis of the ovarian cancer data, however, while these markers are highly significant between cancer and normal groups, our analysis indicated the absolute difference between the two groups was minimal. In addition, we found additional markers than those previously described with greater differences in average intensities. The proposed confidence bands method successfully detected the spiked-in peaks, as well as, secondary peaks generated by adducts and double-charged species. We also illustrate our method utilizing paired gene expression data from a prostate cancer microarray experiment by constructing confidence bands for the fold changes between cancer and normal samples. AVAILABILITY: R-package, 'seie.zip' (license: GNU GPL), is publiclly available at http://research2.dfci.harvard.edu/dfci/MS_spike-in_data/

Temporal genetic program following B-cell receptor cross-linking: altered balance between proliferation and death in healthy and malignant B cells.

Gene expression in cells is a dynamic process but is usually examined at a single time point. We used gene expression profiling over time to build temporal models of gene transcription after B-cell receptor (BCR) signaling in healthy and malignant B cells and chose this as a model since BCR cross-linking induces both cell proliferation and apoptosis, with increased apoptosis in chronic lymphocytic leukemia (CLL) compared to healthy B cells. To determine the basis for this, we examined the global temporal gene expression profile for BCR stimulation and developed a linear combination method to summarize the effect of BCR simulation over all the time points for all patients. Functional learning identified common early events in healthy B cells and CLL cells. Although healthy and malignant B cells share a common genetic pattern early after BCR signaling, a specific genetic program is engaged by the malignant cells at later time points after BCR stimulation. These findings identify the molecular basis for the different functional consequences of BCR cross-linking in healthy and malignant B cells. Analysis of gene expression profiling over time may be used to identify genes that might be rational targets to perturb these pathways.

Extent of coronary artery disease as a predictor of outcomes in acute myocardial infarction complicated by heart failure, left ventricular dysfunction, or both.

BACKGROUND: Left ventricular systolic dysfunction (LVSD) and heart failure (HF) are powerful predictors of poor outcome after acute myocardial infarction (MI). It is not known, however, whether the extent of coronary artery disease (CAD) independently influences cardiovascular (CV) outcomes in these high-risk patients. METHODS: In the VALIANT, 14703 patients were randomly assigned to receive either captopril monotherapy, valsartan monotherapy, or a valsartan and captopril combination between 0.5 and 10 days after acute MI complicated by LVSD, HF, or both. Cox proportional hazards models were used to evaluate the relation between the extent of CAD (the number of diseased vessels as assessed by angiography) and a range of CV outcomes and all-cause mortality. RESULTS: Coronary angiography data were available on 5742 (40%) of the 14703 randomized patients. Single-vessel disease was reported in 1955 patients (34%), 2-vessel disease in 1598 (28%), and 3-vessel disease in 2189 (38%). For all CV outcomes, the risk increased with the severity of CAD (P for trend < .002). A comparison of single-, 2-, and 3-vessel disease showed that, after adjusting for all known covariates, including revascularization and ejection fraction, 2-vessel disease was associated with a 40% increased hazard (P = .008) and 3-vessel disease was associated with an 85% increased hazard (P < .001) for all-cause mortality. The fully adjusted hazard ratios for death and other CV outcomes increased significantly with increasing extent of CAD. CONCLUSIONS: Increasing extent of CAD, as detected by angiography, is a significant and independent risk factor for adverse CV outcomes after MI complicated by HF, LVSD, or both. The observed risk was apparent even after excluding patients who had undergone revascularization.

Inferring loss-of-heterozygosity from unpaired tumors using high-density oligonucleotide SNP arrays.

Loss of heterozygosity (LOH) of chromosomal regions bearing tumor suppressors is a key event in the evolution of epithelial and mesenchymal tumors. Identification of these regions usually relies on genotyping tumor and counterpart normal DNA and noting regions where heterozygous alleles in the normal DNA become homozygous in the tumor. However, paired normal samples for tumors and cell lines are often not available. With the advent of oligonucleotide arrays that simultaneously assay thousands of single-nucleotide polymorphism (SNP) markers, genotyping can now be done at high enough resolution to allow identification of LOH events by the absence of heterozygous loci, without comparison to normal controls. Here we describe a hidden Markov model-based method to identify LOH from unpaired tumor samples, taking into account SNP intermarker distances, SNP-specific heterozygosity rates, and the haplotype structure of the human genome. When we applied the method to data genotyped on 100 K arrays, we correctly identified 99% of SNP markers as either retention or loss. We also correctly identified 81% of the regions of LOH, including 98% of regions greater than 3 megabases. By integrating copy number analysis into the method, we were able to distinguish LOH from allelic imbalance. Application of this method to data from a set of prostate samples without paired normals identified known regions of prevalent LOH. We have developed a method for analyzing high-density oligonucleotide SNP array data to accurately identify of regions of LOH and retention in tumors without the need for paired normal samples.

One- and two-sample nonparametric inference procedures in the presence of a mixture of independent and dependent censoring.

In survival analysis, the event time T is often subject to dependent censorship. Without assuming a parametric model between the failure and censoring times, the parameter Theta of interest, for example, the survival function of T, is generally not identifiable. On the other hand, the collection Omega of all attainable values for Theta may be well defined. In this article, we present nonparametric inference procedures for Omega in the presence of a mixture of dependent and independent censoring variables. By varying the criteria of classifying censoring to the dependent or independent category, our proposals can be quite useful for the so-called sensitivity analysis of censored failure times. The case that the failure time is subject to possibly dependent interval censorship is also discussed in this article. The new proposals are illustrated with data from two clinical studies on HIV-related diseases.

Mature results of a phase III randomized trial of bacillus Calmette-Guerin (BCG) versus observation and BCG plus dacarbazine versus BCG in the adjuvant therapy of American Joint Committee on Cancer Stage I-III melanoma (E1673): a trial of the Eastern Oncology Group.

BACKGROUND: The local and systemic effects of bacillus Calmette-Guerin (BCG) have been known for decades. To investigate the adjuvant effect of BCG on resected American Joint Committee on Cancer (AJCC) Stage I-III melanoma, the Eastern Cooperative Oncology Group conducted a large trial to study the use of BCG alone or a combination of BCG and dacarbazine between 1974 and 1978. METHODS: A total of 734 patients were randomized to 4 clinical groups consolidated into 2 cohorts. Cohort I compared BCG with observation and Cohort II compared BCG with a combination of BCG and dacarbazine. The primary end points were survival time and time to disease progression. RESULTS: Within Cohort I, no statistically significant difference in disease-free survival (DFS) (P = 0.84) or overall survival (OS) (5-year survival 67% vs. 62%; P = 0.40) was observed between BCG treatment and observation. Within Cohort II, the addition of dacarbazine to BCG did not improve DFS (P = 0.74) or OS (P = 0.81) compared with BCG alone. Toxicity was mild to moderate in both cohorts. Although toxicity with this agent is mild, the use of BCG is associated with the development of punctate abscesses in greater than two-thirds of patients treated. CONCLUSIONS: In what to our knowledge is the largest ever trial to test the role of BCG as adjuvant therapy for melanoma, no benefit for BCG was observed for patients with AJCC Stage I-III disease. The mature results of the current trial projected to 30 years confirmed the negative results of previous smaller studies utilizing this agent.