Gravito-electromagnetic analogies

We reexamine and further develop different gravito-electromagnetic (GEM) analogies found in the literature, and clarify the connection between them. Special emphasis is placed in two exact physical analogies: the analogy based on inertial fields from the so-called "1+3 formalism", and the analogy based on tidal tensors. Both are reformulated, extended and generalized. We write in both formalisms the Maxwell and the full exact Einstein field equations with sources, plus the algebraic Bianchi identities, which are cast as the source-free equations for the gravitational field. New results within each approach are unveiled. The well known analogy between linearized gravity and electromagnetism in Lorentz frames is obtained as a limiting case of the exact ones. The formal analogies between the Maxwell and Weyl tensors are also discussed, and, together with insight from the other approaches, used to physically interpret gravitational radiation. The precise conditions under which a similarity between gravity and electromagnetism occurs are discussed, and we conclude by summarizing the main outcome of each approach.Comment: 60 pages, 2 figures. Improved version (compared to v2) with some re-write, notation improvements and a new figure that match the published version; expanded compared to the published version to include Secs. 2.3 and

f(R) theories

Over the past decade, f(R) theories have been extensively studied as one of the simplest modifications to General Relativity. In this article we review various applications of f(R) theories to cosmology and gravity - such as inflation, dark energy, local gravity constraints, cosmological perturbations, and spherically symmetric solutions in weak and strong gravitational backgrounds. We present a number of ways to distinguish those theories from General Relativity observationally and experimentally. We also discuss the extension to other modified gravity theories such as Brans-Dicke theory and Gauss-Bonnet gravity, and address models that can satisfy both cosmological and local gravity constraints.Comment: 156 pages, 14 figures, Invited review article in Living Reviews in Relativity, Published version, Comments are welcom

The association of indwelling urinary catheter with delirium in hospitalized patients and nursing home residents: an explorative analysis from the "Delirium Day 2015"

Backround: Use of indwelling urinary catheter (IUC) in older adults has negative consequences, including delirium. Aim: This analysis, from the "Delirium Day 2015", a nationwide multicenter prevalence study, aim to evaluate the association of IUC with delirium in hospitalized and Nursing Homes (NHs) patients. Methods: Patients underwent a comprehensive geriatric assessment, including the presence of IUC; inclusion criteria were age > 65 years, being Italian speaker and providing informed consent; exclusion criteria were coma, aphasia, end-of-life status. Delirium was assessed using the 4AT test (score ≥ 4: possible delirium; scores 1-3: possible cognitive impairment). Results: Among 1867 hospitalized patients (mean age 82.0 ± 7.5 years, 58% female), 539 (28.9%) had IUC, 429 (22.9%) delirium and 675 (36.1%) cognitive impairment. IUC was significantly associated with cognitive impairment (OR 1.60, 95% CI 1.19-2.16) and delirium (2.45, 95% CI 1.73-3.47), this latter being significant also in the subset of patients without dementia (OR 2.28, 95% CI 1.52-3.43). Inattention and impaired alertness were also independently associated with IUC. Among 1454 NHs residents (mean age 84.4 ± 7.4 years, 70.% female), 63 (4.3%) had IUC, 535 (36.8%) a 4AT score ≥ 4, and 653 (44.9%) a 4AT score 1-3. The multivariate logistic regression analysis did not show a significant association between 4AT test or its specific items with IUC, neither in the subset of patients without dementia. Discussion: We confirmed a significant association between IUC and delirium in hospitalized patients but not in NHs residents. Conclusion: Environmental and clinical factors of acute setting might contribute to IUC-associated delirium occurrence

Role of antioxidants in atherosclerosis: Epidemiological and clinical update

Low density lipoprotein (LDL) oxidative modification in the vascular wall seems to be a key factor in atherosclerosis development. Oxidised LDLs might recruit monocytes and favour their transformation into foam cells through a receptor-mediated intake (scavenger pathway). Moreover oxidised LDLs show cytotoxic potential which is probably responsible for endothelial cell damage and macrophage degeneration in the atherosclerotic human plaque. Following the oxidation hypothesis of atherosclerosis the role of natural antioxidants, i.e. Vitamin C, Vitamin E and carotenoids, has been investigated in a large number of epidemiological, clinical and experimental studies. Animal studies indicate that dietary antioxidants may reduce atherosclerosis progression, and observational data in humans suggest that antioxidant vitamin ingestion is associated with reduced cardiovascular disease, but the results of randomised controlled trials are mainly disappointing. It has been suggested that natural antioxidants may be effective only in selected subgroups of patients with high levels of oxidative stress or depletion of natural antioxidant defence systems. The favourable effects shown by some studies relating antioxidant dietary intake and cardiovascular disease, may have been exerted by other chemicals present in foods. Flavonoids are the ideal candidates, since they are plentiful in foods containing antioxidant vitamins (i.e. fruits and vegetables) and are potent antioxidants. Tea and wine, rich in flavonoids, seem to have beneficial effects on multiple mechanisms involved in atherosclerosis. Future studies should probably select patients in a context of high-oxidative stress / low-antioxidant defence, to verify if antioxidants may really prove useful as therapeutic anti-atherosclerotic agents

Risk factors for short term mortality in older subjects with acute ischemic stroke

BACKGROUND: Stroke is the third cause of death in older individuals living in Western Countries. The identification of predictors for mortality after stroke has a major importance for clinicians in order to allow the implementation of therapeutic and preventive strategies. OBJECTIVE: To evaluate the association between clinical and laboratory parameters and 30-days total mortality in a large sample of older patients with stroke. METHODS: 469 older patients (median age: 80.0 years) consecutively hospitalized for acute ischemic stroke were enrolled. The data recorded included: (1) clinical features of stroke; (2) routine clinical chemistry analyses; (3) medical history, and (4) 12-lead ECG. All patients underwent computed tomography scan of the brain. Stroke type was classified by the Oxfordshire Community Stroke Project system. RESULTS: 130 subjects died within 30 days after stroke, with an overall mortality of 27.7%. At univariate analysis, altered levels of consciousness (ALC), congestive heart failure, atrial fibrillation, previous stroke, high blood glucose, fibrinogen and blood sedimentation rate levels, higher white blood cell count, lower serum albumin and iron levels were associated with mortality. Multivariate logistic regression analysis indicated that short-term mortality was associated with ALC (OR: 11.80; CI 95%: 5.50-24.00), congestive heart failure (OR: 3.06; CI 95%: 1.04-8.80), and age (OR: 1.04; CI 95%: 1.002-1.09) independent of gender, previous stroke, AF, fasting blood glucose, serum albumin, serum iron, and white blood cell count. In patients with ALC (high-mortality rate: 63.6%), only hyperglycemia (III vs. I tertile, OR: 9.60; CI 95%: 1.65-52.50) was associated with mortality after multivariate adjustment. CONCLUSION: Our study highlights the role of ALC and congestive heart failure in the short-term prognostic stratification of older patients with acute ischemic stroke. Furthermore, our results support the value of post-stroke hyperglycemia as a marker for short-term mortality also in advanced age, and particularly in the presence of ALC and in nondiabetic individuals

Omega-3 Polyunsaturated Fatty Acids and Immune-Mediated Diseases: Inflammatory Bowel Disease and Rheumatoid Arthritis

Inflammation is part of the normal host response to infection and injury. However, inappropriate inflammation contributes to several diseases, including inflammatory bowel disease (IBD) and rheumatoid arthritis (RA). Both conditions are characterized by the excessive production of inflammatory cytokines, arachidonic acid (AA)-derived eicosanoids, and other inflammatory agents (e. g., reactive oxygen species, adhesion molecules). By virtue of their anti-inflammatory action, omega-3 polyunsaturated fatty acids (PUFA) may be beneficial in inflammatory diseases. A large body of evidence supports a protective effect of omega-3 PUFA in experimental animal and ex-vivo models of Crohn's disease (CD), Ulcerative colitis (UC) and RA. Although fish oil supplementation in patients with IBD results in omega-3 PUFA incorporation into gut mucosal tissue and modification of inflammatory mediator profiles, the evidence of clinical benefits of omega-3 PUFA is weak. On the other hand, more convincing data support the efficacy of omega-3 PUFA in reducing pain, number of tender joints, duration of morning stiffness, use of non-steroidal anti-inflammatory drugs and improving physical performance in RA patients. In both IBD and RA further clinical trials with large sample size are needed to clarify the efficacy of omega-3 PUFA as a treatment

The effect of polyunsaturated fatty acids on bone health

The essential polyunsaturated fatty acids (PUFAs) are divided into two classes, n-3 (ω-3) and n-6 (ω-6) and their dietary precursors are α-linolenic (ALA) and linoleic acid (LA), respectively. PUFAs are precursors of a wide range of metabolites, for example eicosanoids like prostaglandins and leukotrienes, which play critical roles in the regulation of a variety of biological processes, including bone metabolism. A large body of evidence supports an effect of PUFA on bone metabolism which may be mediated by regulation of osteoblastogenesis and osteoclast activity, change of membrane function, decrease in inflammatory cytokines, such as interleukin-1 (IL-1), interleukin-6 (IL-6), and tumour necrosis factor alpha (TNF-α), modulation of peroxisome proliferators-activated receptor γ (PPARγ) and influence in NO secretion and NO synthase. Animal studies have shown that a higher dietary omega-3/omega-6 fatty acids ratio is associated with beneficial effects on bone health. Human studies conducted in elderly subjects suggest that omega-3 instead of omega-6 has a positive effect on bone metabolism. In spite of increasing evidence, studies conducted in humans do not allow us to draw a definitive conclusion on the usefulness of PUFAs in clinical practice

Low plasma selenium concentrations and mortality among older community-dwelling adults: the InCHIANTI Study

Aims: We examined the relationship between plasma selenium levels at enrollment and all-cause mortality over a 6-year period among participants in the InCHIANTI study. Methods: 1042 men and women >= 65 years from the InCHIANTI study, a population-based study of older adults living in the Chianti region of Tuscany, a population-based cohort in Tuscany, Italy. Plasma selenium was measured at enrollment (1998-2000), and vital status was ascertained until May 2006. Results: During follow-up, 237 participants (22.7%) died. At enrollment, mean (SD) plasma selenium concentrations among participants who survived or died were 0.96 (0.14) and 0.87 (0.18) mu mol/L (p<0.0001), respectively. The proportion of participants who died, from lowest to highest quartile of selenium, was 41.3, 27.0, 18.1 and 13.5% (p<0.0001 by Mantel-Haenszel chi-square). After adjusting for age, sex, education, and chronic diseases, adults in the lowest quartile of plasma selenium at enrollment had higher mortality compared with those in the highest quartile (Hazard Ratio (HR) 1.60, 95% Confidence Interval (CI) 1.04-2.47, p=0.034). Conclusion: Low plasma selenium may be an independent predictor of mortality among older adults living in the community

Plasma polyunsaturated fatty acids and the decline of renal function

BACKGROUND: Recent studies suggest an association between polyunsaturated fatty acids (PUFAs) and the development of chronic kidney disease. The aim of this study was to examine the relationship between PUFAs and renal function in older adults. METHODS: We performed a cross-sectional and prospective analysis of 931 adults, >= 65 years old, enrolled in the InCHIANTI study, a population-based cohort in Tuscany, Italy. Plasma PUFAs were measured at enrollment, and creatinine clearance was estimated by the Cockcroft-Gault equation at baseline and after 3-year follow-up. RESULTS: At enrollment, participants with higher creatinine clearance had higher concentrations of HDL cholesterol, total plasma PUFAs, plasma n-3 fatty acid (FA), and plasma n-6 FA and lower triglycerides. From enrollment to the 3-year follow-up visit, creatinine clearance declined by 7.8 (12.2) mL/min (P <0.0001). Baseline total plasma PUFAs, n-3 FA, n-6 FA, and linoleic, linolenic, and arachidonic acids were strong independent predictors of less steep decline in creatinine clearance from baseline to follow-up (P <0.0001, after adjusting for baseline creatinine clearance). After adjusting for baseline creatinine, baseline total plasma PUFAs, n-3 FA, and linoleic, linolenic, and arachidonic acids were negatively associated with creatinine at 3-year follow-up. Participants with higher plasma PUFAs at enrollment had a lower risk of developing renal insufficiency, defined by a creatinine clearance <60 mL/min, during 3-year follow-up. CONCLUSION: High PUFA concentrations, both n-3 FA and n-6 FA, may attenuate the Age-associated decline in renal function among older community-dwelling women and men. (c) 2008 American Association for Clinical Chemistry

Prior antiplatelet drug use and short-term mortality in older patients with acute ischemic stroke (AIS).

Abstract Some studies suggest that previous treatment with antiplatelet agents (AA) might reduce ischemic stroke severity and improve outcomes in terms of clinical deficits or mortality. We evaluated the effect of the prior chronic use of AA on short-term (30 days) mortality in a sample of consecutive patients with AIS. Four hundred thirty-nine older patients (>65 years) with “major” AIS (modified Rankin scale≥3) consecutively admitted to the University ward of Internal Medicine or Geriatrics were enrolled. Stroke was classified according to Oxfordshire Community Stroke Project (OCSP). Data recorded included: (1) clinical features; (2) medical history including home therapies, and vascular risk factors; (3) routine clinical chemistry analyzes (verb)/analyses (noun). Short-term (30 days) mortality was 27.6%. One hundred fifteen subjects (26.2%) were taking AA before admission. Compared with subjects not treated, subjects taking AA were characterized by higher prevalence of recurrent stroke (35% vs. 22%). In this group, a trend toward a higher prevalence of congestive heart failure (CHF), smoking, and altered levels of consciousness (ALC) was noted. Stroke type and short-term mortality (33% vs. 26.2%; odds ratio=OR=1.25; 95% confidence interval=CI=0.75–2.10, age and gender adjusted) were not different between the two groups. Adjustment for glucose, CHF, previous stroke, smoking, and ALC did not change mortality risk (OR=0.83; 95%CI=0.40–1.72). We conclude that in older patients hospitalized for “major” AIS, prior use of AA was not associated with any benefit in terms of short-term mortality both in patients with first, as well as in those with recurrent ischemic stroke