Sparsest factor analysis for clustering variables: a matrix decomposition approach

We propose a new procedure for sparse factor analysis (FA) such that each variable loads only one common factor. Thus, the loading matrix has a single nonzero element in each row and zeros elsewhere. Such a loading matrix is the sparsest possible for certain number of variables and common factors. For this reason, the proposed method is named sparsest FA (SSFA). It may also be called FA-based variable clustering, since the variables loading the same common factor can be classified into a cluster. In SSFA, all model parts of FA (common factors, their correlations, loadings, unique factors, and unique variances) are treated as fixed unknown parameter matrices and their least squares function is minimized through specific data matrix decomposition. A useful feature of the algorithm is that the matrix of common factor scores is re-parameterized using QR decomposition in order to efficiently estimate factor correlations. A simulation study shows that the proposed procedure can exactly identify the true sparsest models. Real data examples demonstrate the usefulness of the variable clustering performed by SSFA

Primary pericardial malignant mesothelioma and response to radiation therapy

We report a case of a primary pericardial malignant mesothelioma. A 59-year-old male presented with episodic chest pain and dyspnea on exertion. Cardiac magnetic resonance imaging revealed a large mass in the pericardium attached to the right ventricle. Partial resection of the mass was undertaken revealing malignant mesothelioma, byphasic type. The patient was treated with chemotherapy intermittently over a period of 3 years, but his disease continued to progress. The patient was then treated with definitive radiation therapy to 64 Gy to the primary tumor using a six field 3D conformal technique. The patient remains free of progressive disease 86 months from the time of diagnosis and 50 months from the completion of his radiotherapy

High burden and frailty: association with poor cognitive performance in older caregivers living in rural areas

Introduction: Older caregivers living in rural areas may be exposed to three vulnerable conditions, i.e., those related to care, their own aging, and their residence context. Objective: To analyze the association of burden and frailty with cognition performance in older caregivers in rural communities. Method: In this cross-sectional survey, 85 older caregivers who cared for dependent elders were included in this study. Global cognition (Addenbrooke's Cognitive Examination – Revised; Mini Mental State Examination), burden (Zarit Burden Interview) and frailty (Fried's frailty phenotype) were assessed. All ethical principles were observed. Results: Older caregivers were mostly women (76.7%); mean age was 69 years. Cognitive impairment was present in 15.3%, severe burden in 8.2%, frailty in 9.4%, and pre-frailty in 52.9% of the older caregivers. More severely burdened or frail caregivers had worse cognitive performance than those who were not, respectively (ANOVA test). Caregivers presenting a high burden level and some frailty degree (pre-frail or frail) simultaneously were more likely to have a reduced global cognition performance. Conclusion: A significant number of older caregivers had low cognitive performance. Actions and resources to decrease burden and physical frailty may provide better cognition and well-being, leading to an improved quality of life and quality of the care provided by the caregivers

Novel image–novel location object recognition task sensitive to age-related cognitive decline in nondemented elderly

Traditional tests used in the clinic to identify dementia, such as the mini-mental state examination (MMSE), are useful to identify severe cognitive impairments but might be less sensitive to detect more subtle age-related cognitive changes. Previously, the novel image–novel location (NINL) object recognition test was shown to be sensitive to detect effects of apolipoprotein E4, a risk factor for developing age-related cognitive decline and Alzheimer’s disease, in nondemented elderly. In the present longitudinal study, performance on the MMSE and the NINL tests were compared over a 4-year period. Individual NINL scores over this period were highly correlated. In addition, while MMSE scores did not change over the 4-year period, NINL scores did. In a final testing session of a subset of the participants, NINL scores correlated with logical memory and word recall lists, cognitive tasks used to detect dementia in the clinic, as well as clinical dementia rating scales. These results support that the NINL might be a valuable tool to assess age-related cognitive decline

Dual-tasking and gait in people with Mild Cognitive Impairment. The effect of working memory

<p>Abstract</p> <p>Background</p> <p>Cognition and mobility in older adults are closely associated and they decline together with aging. Studies evaluating associations between cognitive factors and gait performance in people with Mild Cognitive Impairment (MCI) are scarce. In this study, our aim was to determine whether specific cognitive factors have a more identifiable effect on gait velocity during dual-tasking in people with MCI.</p> <p>Methods</p> <p>Fifty-five participants, mean age 77.7 (SD = 5.9), 45% women, with MCI were evaluated for global cognition, working memory, executive function, and attention. Gait Velocity (GV) was measured under a single-task condition (single GV) and under two dual-task conditions: 1) while counting backwards (counting GV), 2) while naming animals (verbal GV). Multivariable linear regression analysis was used to examine associations with an alpha-level of 0.05.</p> <p>Results</p> <p>Participants experienced a reduction in GV while engaging in dual-task challenges (p < 0.005). Low executive function and working memory performances were associated with slow single GV (p = 0.038), slow counting GV (p = 0.017), and slow verbal GV (p = 0.031). After adjustments, working memory was the only cognitive factor which remained significantly associated with a slow GV.</p> <p>Conclusion</p> <p>In older adults with MCI, low working memory performance was associated with slow GV. Dual-task conditions showed the strongest associations with gait slowing. Our findings suggest that cortical control of gait is associated with decline in working memory in people with MCI.</p

Current research in biotechnology: Exploring the biotech forefront

Biotechnology is an evolving research field that covers a broad range of topics. Here we aimed to evaluate the latest research literature, to identify prominent research themes, major contributors in terms of institutions, countries/regions, and journals. The Web of Science Core Collection online database was searched to retrieve biotechnology articles published since 2017. In total, 12,351 publications were identified and analyzed. Over 8500 institutions contributed to these biotechnology publications, with the top 5 most productive ones scattered over France, China, the United States of America, Spain, and Brazil. Over 140 countries/regions contributed to the biotechnology research literature, led by the United States of America, China, Germany, Brazil, and India. Journal of Bioscience and Bioengineering was the most productive journal in terms of number of publications. Metabolic engineering was among the most prevalent biotechnology study themes, and Escherichia coli and Saccharomyces cerevisiae were frequently used in biotechnology investigations, including the biosynthesis of useful biomolecules, such as myo-inositol (vitamin B8), monoterpenes, adipic acid, astaxanthin, and ethanol. Nanoparticles and nanotechnology were identified too as emerging biotechnology research themes of great significance. Biotechnology continues to evolve and will remain a major driver of societal innovation and development

Dizziness reported by elderly patients in family practice: prevalence, incidence, and clinical characteristics

Background: Although dizziness in elderly patients is very common in family practice, most prevalence studies on dizziness are community-based and include a study population that is not representative of family practice. The aim of this study was to investigate the prevalence and incidence of dizziness reported by elderly patients in family practice, to describe their final diagnoses as recorded by the family physician, and to compare the clinical characteristics of dizzy patients with those of non-dizzy patients. Methods: Data were obtained from the Second Dutch National Survey of General Practice, a prospective registration study which took place over a 12-month period in 2001. We developed a search strategy consisting of 15 truncated search terms (based on Dutch synonyms for dizziness), and identified all patients aged 65 or older who visited their family physician because of dizziness (N=3,990). We used the mid-time population as denominator to calculate the prevalence and incidence, and for group comparisons we used the Student's t and Chi-square test, and logistic regression analysis. Results: The one-year prevalence of dizziness in family practice in patients aged 65 or older was 8.3%, it was higher in women than in men, and it increased with age. In patients aged 85 or older the prevalence was similar for men and women. The incidence of dizziness was 47.1 per 1000 person-years. For 39% of the dizzy patients the family physicians did not specify a diagnosis, and recorded a symptom diagnosis as the final diagnosis. Living alone, lower level of education, pre-existing cerebrovascular disease, and pre-existing hypertension were independently associated with dizziness. Conclusions: Dizziness in family practice patients increases with age. It is more common in women than in men, but this gender difference disappears in the very old. Because a large proportion of dizzy elderly patients in family practice remains undiagnosed, it would be worthwhile to carry out more diagnostic research on dizziness in a family practice setting

Mitochondrial chaotic dynamics: Redox-energetic behavior at the edge of stability

Mitochondria serve multiple key cellular functions, including energy generation, redox balance, and regulation of apoptotic cell death, thus making a major impact on healthy and diseased states. Increasingly recognized is that biological network stability/instability can play critical roles in determining health and disease. We report for the first-time mitochondrial chaotic dynamics, characterizing the conditions leading from stability to chaos in this organelle. Using an experimentally validated computational model of mitochondrial function, we show that complex oscillatory dynamics in key metabolic variables, arising at the “edge” between fully functional and pathological behavior, sets the stage for chaos. Under these conditions, a mild, regular sinusoidal redox forcing perturbation triggers chaotic dynamics with main signature traits such as sensitivity to initial conditions, positive Lyapunov exponents, and strange attractors. At the “edge” mitochondrial chaos is exquisitely sensitive to the antioxidant capacity of matrix Mn superoxide dismutase as well as to the amplitude and frequency of the redox perturbation. These results have potential implications both for mitochondrial signaling determining health maintenance, and pathological transformation, including abnormal cardiac rhythms.publishedVersionKembro, Jackelyn Melissa. Universidad Nacional de Córdoba. Facultad de Ciencias Exactas, Físicas y Naturales; Argentina.Kembro, Jackelyn Melissa. Consejo Nacional de Investigaciones Científicas y Técnicas. Instituto de Investigaciones Biológicas y Tecnológicas; Argentina.Cortassa, Sonia. National Institutes of Health. NIH · NIA Intramural Research Program; Estados Unidos.Lloyd, David. Cardiff University. School of Biosciences 1; Inglaterra.Sollot, Steven. Johns Hopkins University. Laboratory of Cardiovascular Science; Estados Unidos.Sollot, Steven. Johns Hopkins University. Laboratory of Cardiovascular Science; Estados Unidos