322 research outputs found
Toward a New Paradigm for the Evolution of Developmental and Growth-Pattern Systems in Plants and Animals
Genetically controlled and environmentally responsive mutation as a significant feature of evolution has very likely occurred on different genomic levels. The evolution of developmental and growth-pattern systems in plants and animals could have occurred through a karyotypic mutator system creating controlled, frequent genomic changes on the karyotypic level in response to environmental stresses, such as temperature changes. Such a mutator system generating controlled karyotypic changes at very high frequency in response to stress was discovered. in the fungus, Aspergillus nidulans, once classified within the plant kingdom. This mutator system is itself representative of a basic, responsive developmental system producing changes in growth-pattern, morphology, and changes ensuing in a new pattern of differentiation, which are adaptive. Such a developmental, karyotypic mutator system may itself have evolved, through its own self-controlled evolution, into types of complex developmental systems that, through controlled, specific, and minute karyotypic changes during ontogeny, could control patterns of development in plants and animals, integrating different levels of organization. The deeper implications for development and evolution are illustrated, suggesting a new paradigm
Front-to-Rear Membrane Tension Gradient in Rapidly Moving Cells
AbstractMembrane tension is becoming recognized as an important mechanical regulator of motile cell behavior. Although membrane-tension measurements have been performed in various cell types, the tension distribution along the plasma membrane of motile cells has been largely unexplored. Here, we present an experimental study of the distribution of tension in the plasma membrane of rapidly moving fish epithelial keratocytes. We find that during steady movement the apparent membrane tension is ∼30% higher at the leading edge than at the trailing edge. Similar tension differences between the front and the rear of the cell are found in keratocyte fragments that lack a cell body. This front-to-rear tension variation likely reflects a tension gradient developed in the plasma membrane along the direction of movement due to viscous friction between the membrane and the cytoskeleton-attached protein anchors embedded in the membrane matrix. Theoretical modeling allows us to estimate the area density of these membrane anchors. Overall, our results indicate that even though membrane tension equilibrates rapidly and mechanically couples local boundary dynamics over cellular scales, steady-state variations in tension can exist in the plasma membranes of moving cells
Relationship between the extent of non-viable myocardium and regional left ventricular function in chronic ischemic heart disease
Purpose. To define the relationship between left ventricular (LV) regional contractile function and the extent of myocardial scar in patients with chronic ischemic heart disease and multi-vessel coronary artery disease. Methods. Twenty-three patients with chronic ischemic heart disease and 5 healthy volunteers underwent magnetic resonance imaging (MRI). In patients, the relative area ( Percent Scar) and transmural extent (Transmurality) of myocardial infarction were computed from short-axis delayed enhancement images. In each image, myocardial segments were categorized based on the extent of infarction they contained, with 6 categories each for Percent Scar and Transmurality: normal, from healthy volunteers; and 0%; 1–25%, 26–50%, 51–75%, and \u3e 76% from patients. In patients and volunteers, regional LV function was quantified by absolute systolic wall thickening from cine images and midwall circumferential strain using tagged images. Results. Compared to normal segments, regional LV function in patients was significantly diminished in all scar extent intervals, with wall thickening=-8% for all categories. Systolic wall thickening was reduced significantly in all categories above 50% Percent Scar and above 25% Transmurality in patients, relative to corresponding 0% categories. Circumferential strain was significantly reduced above 25% Percent Scar and above 25% Transmurality. Conclusions. In patients with chronic ischemic heart disease and multivessel coronary artery disease, wall thickening was more sensitive to changes in scar Transmurality than to changes in Percent Scar. However, circumferential strain was equally sensitive to both indices. In general, circumferential strain was more sensitive than wall thickening to increases in scar extent
Relationship between the extent of non-viable myocardium and regional left ventricular function in chronic ischemic heart disease
Purpose. To define the relationship between left ventricular (LV) regional contractile function and the extent of myocardial scar in patients with chronic ischemic heart disease and multi-vessel coronary artery disease. Methods. Twenty-three patients with chronic ischemic heart disease and 5 healthy volunteers underwent magnetic resonance imaging (MRI). In patients, the relative area ( Percent Scar) and transmural extent (Transmurality) of myocardial infarction were computed from short-axis delayed enhancement images. In each image, myocardial segments were categorized based on the extent of infarction they contained, with 6 categories each for Percent Scar and Transmurality: normal, from healthy volunteers; and 0%; 1–25%, 26–50%, 51–75%, and \u3e 76% from patients. In patients and volunteers, regional LV function was quantified by absolute systolic wall thickening from cine images and midwall circumferential strain using tagged images. Results. Compared to normal segments, regional LV function in patients was significantly diminished in all scar extent intervals, with wall thickening=-8% for all categories. Systolic wall thickening was reduced significantly in all categories above 50% Percent Scar and above 25% Transmurality in patients, relative to corresponding 0% categories. Circumferential strain was significantly reduced above 25% Percent Scar and above 25% Transmurality. Conclusions. In patients with chronic ischemic heart disease and multivessel coronary artery disease, wall thickening was more sensitive to changes in scar Transmurality than to changes in Percent Scar. However, circumferential strain was equally sensitive to both indices. In general, circumferential strain was more sensitive than wall thickening to increases in scar extent
The association between benign prostatic hyperplasia and chronic kidney disease in community-dwelling men
The association between benign prostatic hyperplasia and chronic kidney disease in community-dwelling men.BackgroundBenign prostatic hyperplasia (BPH) and chronic kidney disease are important public health problems in older men. Previous referral-based studies disagree on whether BPH is associated with chronic kidney disease. The objective of this study was to determine the community-based association between clinical measures of BPH and chronic kidney disease.MethodsA community-based sample of 2115 white men (ages 40–79 years) was randomly selected from the Olmsted County, Minnesota population (55% participation rate) in 1990. A random subsample (N = 476) had a detailed clinical evaluation. This evaluation included a questionnaire with similar queries to the International Prostate Symptom Score (IPSS), peak urinary flow rates (uroflowmeter), postvoid residual urine volume (ultrasound), prostate volume (ultrasound), serum prostate specific antigen (PSA), and serum creatinine.ResultsAfter adjustment for age, hypertension, diabetes, leukocyte esterase positive (possible urinary tract infection), and smoking, chronic kidney disease [serum creatinine ≥133 μmol/L (1.5 mg/dL)] was associated with diminished peak urinary flow rate (<15 mL/sec) by an odds ratio (OR) = 2.96 (95% CI 1.30–7.01), moderate-severe lower urinary tract symptoms (IPSS >7) by an OR = 2.91 (95% CI 1.32–6.62), and chronic urinary retention (postvoid residual >100 mL) by an OR = 2.28 (95% CI 0.66–6.68). There was no association with a prostate volume >30 mL by an OR = 0.56 (95% CI 0.22–1.37) or PSA >1.4 ng/mL by an OR = 1.17 (95% CI 0.47–2.81).ConclusionThere was a cross-sectional association between signs and symptoms of bladder outlet obstruction and chronic kidney disease in community-dwelling men. Prostatic enlargement was not associated with chronic kidney disease
A global-scale data set of mining areas
The area used for mineral extraction is a key indicator for understanding and mitigating the environmental impacts caused by the extractive sector. To date, worldwide data products on mineral extraction do not report the area used by mining activities. In this paper, we contribute to filling this gap by presenting a new data set of mining extents derived by visual interpretation of satellite images. We delineated mining areas within a 10 km buffer from the approximate geographical coordinates of more than six thousand active mining sites across the globe. The result is a global-scale data set consisting of 21,060 polygons that add up to 57,277 km². The polygons cover all mining above-ground features that could be identified from the satellite images, including open cuts, tailings dams, waste rock dumps, water ponds, and processing infrastructure. The data set is available for download from https://doi.org/10.1594/PANGAEA.910894 and visualization at www.fineprint.global/viewer
Exercise-induced QT/R-R-interval hysteresis as a predictor of myocardial ischemia
Abstract: Objectives: Exercise-induced QT/RR hysteresis exists when, for a given R-R interval, the QT interval duration is shorter during recovery after exercise than during exercise. We sought to assess the association between QT/RR hysteresis and imaging evidence of myocardial ischemia. Background: Because ischemia induces cellular disturbances known to decrease membrane action potential duration, we hypothesized a correlation between QT/RR and myocardial ischemia
Prior exercise and antioxidant supplementation: effect on oxidative stress and muscle injury
<p>Abstract</p> <p>Background</p> <p>Both acute bouts of prior exercise (preconditioning) and antioxidant nutrients have been used in an attempt to attenuate muscle injury or oxidative stress in response to resistance exercise. However, most studies have focused on untrained participants rather than on athletes. The purpose of this work was to determine the independent and combined effects of antioxidant supplementation (vitamin C + mixed tocopherols/tocotrienols) and prior eccentric exercise in attenuating markers of skeletal muscle injury and oxidative stress in resistance trained men.</p> <p>Methods</p> <p>Thirty-six men were randomly assigned to: no prior exercise + placebo; no prior exercise + antioxidant; prior exercise + placebo; prior exercise + antioxidant. Markers of muscle/cell injury (muscle performance, muscle soreness, C-reactive protein, and creatine kinase activity), as well as oxidative stress (blood protein carbonyls and peroxides), were measured before and through 48 hours of exercise recovery.</p> <p>Results</p> <p>No group by time interactions were noted for any variable (P > 0.05). Time main effects were noted for creatine kinase activity, muscle soreness, maximal isometric force and peak velocity (P < 0.0001). Protein carbonyls and peroxides were relatively unaffected by exercise.</p> <p>Conclusion</p> <p>There appears to be no independent or combined effect of a prior bout of eccentric exercise or antioxidant supplementation as used here on markers of muscle injury in resistance trained men. Moreover, eccentric exercise as used in the present study results in minimal blood oxidative stress in resistance trained men. Hence, antioxidant supplementation for the purpose of minimizing blood oxidative stress in relation to eccentric exercise appears unnecessary in this population.</p
Therapeutic mitigation of measles-like immune amnesia and exacerbated disease after prior respiratory virus infections in ferrets
Measles cases have surged pre-COVID-19 and the pandemic has aggravated the problem. Most measles-associated morbidity and mortality arises from destruction of pre-existing immune memory by measles virus (MeV), a paramyxovirus of the morbillivirus genus. Therapeutic measles vaccination lacks efficacy, but little is known about preserving immune memory through antivirals and the effect of respiratory disease history on measles severity. We use a canine distemper virus (CDV)-ferret model as surrogate for measles and employ an orally efficacious paramyxovirus polymerase inhibitor to address these questions. A receptor tropism-intact recombinant CDV with low lethality reveals an 8-day advantage of antiviral treatment versus therapeutic vaccination in maintaining immune memory. Infection of female ferrets with influenza A virus (IAV) A/CA/07/2009 (H1N1) or respiratory syncytial virus (RSV) four weeks pre-CDV causes fatal hemorrhagic pneumonia with lung onslaught by commensal bacteria. RNAseq identifies CDV-induced overexpression of trefoil factor (TFF) peptides in the respiratory tract, which is absent in animals pre-infected with IAV. Severe outcomes of consecutive IAV/CDV infections are mitigated by oral antivirals even when initiated late. These findings validate the morbillivirus immune amnesia hypothesis, define measles treatment paradigms, and identify priming of the TFF axis through prior respiratory infections as risk factor for exacerbated morbillivirus disease.</p
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