Surfaces coated with the naturally-occurring polysaccharide chitosan (partially deacetylated poly N-acetyl glucosamine) resisted biofilm formation by bacteria and yeast. Reductions in biofilm viable ...cell numbers ranging from 95% to 99.9997% were demonstrated for Staphylococcus
epidermidis, Staphylococcus aureus, Klebsiella pneumoniae, Pseudomonas aeruginosa and Candida albicans on chitosan-coated surfaces over a 54-h experiment in comparison to controls. For instance, chitosan-coated surfaces reduced S. epidermidis surface-associated
growth more than 5.5
10
log units (99.9997%) compared to a control surface. As a comparison, coatings containing a combination of the antibiotics minocycline and rifampin reduced S. epidermidis growth by 3.9
10
log units (99.99%) and coatings containing the antiseptic
chlorhexidine did not significantly reduce S. epidermidis surface associated growth as compared to controls. The chitosan effects were confirmed with microscopy. Using time-lapse fluorescence microscopy and fluorescent-dye-loaded S. epidermidis, the permeabilization of these
cells was observed as they alighted on chitosan-coated surfaces. This suggests chitosan disrupts cell membranes as microbes settle on the surface. Chitosan offers a flexible, biocompatible platform for designing coatings to protect surfaces from infection.
Cancer patients, including breast cancer patients, live in a hypercoagulable state. Chemo- and hormone- therapy used in the treatment of breast cancer increases the risk of thrombosis. Due to ...differences in health care services between developed and developing countries, the survival rate of women with breast cancer in developing countries is low. Consequently, ethnomedicines are used and their efficacy as potential alternatives are being scientifically explored. The seed oils of Kigelia africana, Ximenia caffra and Mimusops zeyheri have anti-proliferative effects on hormone-dependent (MCF-7) and cytotoxic effects on hormone-independent (MDA-MB-231) breast cancer cells. In this study, we determined if these seed oils reduce the thrombogenic ability of breast cancer cells by measuring the platelet surface expression of the activation-specific antigens CD62P and CD63. MDA-MB-231 and MCF-7 cells were pretreated with the seed oils before being exposed to whole blood of human female volunteers. An increase in CD62P and CD63 expression following whole blood exposure to untreated breast cancer cells was observed. Treated MDA-MB-231 cells reduced CD62P and CD63 expression while treated MCF-7 cells increased CD62P and decreased CD63 expression. Kigelia africana, Ximenia caffra and Mimusops zeyheri seed oils are able to reduce the thrombogenic ability of MDA-MB-231 breast cancer cells.
Covering: 2000 to 2020. trans-Bicyclo4.4.0decane/decene (such as trans-decalin and trans-octalin)-containing natural products display a wide range of structural diversity and frequently exhibit ...potent and selective antibacterial activities. With one of the major factors in combatting antibiotic resistance being the discovery of novel scaffolds, the efficient construction of these natural products is an attractive pursuit in the development of novel antibiotics. This highlight aims to provide a critical analysis on how the presence of dense architectural and stereochemical complexity necessitated special strategies in the synthetic pursuits of these natural trans-bicyclo4.4.0decane/decene antibiotics.
In experiments on operant behavior, other activities, called “background” activities, compete with the operant activities. Herrnstein's () formulation of the matching law included background ...reinforcers in the form of a parameter rO, but remained vague about the activities (BO) that produce rO. To gain more understanding, we analyzed data from three studies of performance with pairs of variable‐interval schedules that changed frequently in the relative rate at which they produced food: Baum and Davison (), Belke and Heyman (), and Soto, McDowell, and Dallery (2005). Results sometimes deviated from the matching law, suggesting variation in rO. When rO was calculated from the matching equation, two results emerged: (a) rO is directly proportional to BO, as in a ratio schedule; and (b) rO and BO depend on the food rate, which is to say that BO consists of activities induced by food, as a phylogenetically important event. Other activities unrelated to food (BN) correspond to Herrnstein's original conception of rO and may be included in the matching equation. A model based on Baum's (Baum, 2012) concepts of allocation, induction, and contingency explained the deviations from the matching law. In the model, operant activity B, BO, and BN competed unequally in the time allocation: B and BO both replaced BN, BO replaced lever pressing (Soto et al.), and key pecking replaced BO (Baum & Davison). Although the dependence of rO and BO on food rate changes Herrnstein's () formulation, the model preserved the generalized matching law for operant activities by incorporating power‐function induction.
Background
Cardiovascular disease (CVD) is the leading cause of global mortality. Although the incidence may be reduced with regular exercise, the health benefits of a single bout of exercise on ...selected CVD risk factors are not well understood. The primary objective of this review is to consider the transient effects of exercise on immune (neutrophil count) and inflammatory (interleukin-6 IL-6, C-reactive protein CRP) markers in untrained adults.
Methods
MEDLINE, EMBASE, CINAHL, Sports Discus and Cochrane were searched for relevant studies published from January 1946 to May 2013. Randomised controlled or crossover studies which measured any of these parameters in untrained but otherwise healthy participants in the 48 h following about of exercise, less than 1 h in duration were included.
Results
Ten studies met the inclusion criteria. The results indicate a single bout of aerobic or resistance exercise of moderate to high intensity promotes an increase in IL-6 (145 %) and neutrophil counts (51 %). It appears that 30–60 min of moderate to high intensity exercise is necessary to elicit such changes although variables such as the mode, intensity and pattern of exercise also affect the response. The acute response of CRP within the included studies is equivocal.
Conclusions
Although responses to CRP are inconsistent, a single bout of exercise can increase the activity of both circulating IL-6 and neutrophil counts in untrained adults. These immune and inflammatory responses to a single bout of exercise may be linked to a range of health benefits.
In studies of operant choice, when one schedule of a concurrent pair is varied while the other is held constant, the constancy of the constant schedule may exert discriminative control over ...performance. In our earlier experiments, schedules varied reciprocally across components within sessions, so that while food ratio varied food rate remained constant. In the present experiment, we held one variable‐interval (VI) schedule constant while varying the concurrent VI schedule within sessions. We studied five conditions, each with a different constant left VI schedule. On the right key, seven different VI schedules were presented in seven different unsignaled components. We analyzed performances at several different time scales. At the longest time scale, across conditions, behavior ratios varied with food ratios as would be expected from the generalized matching law. At shorter time scales, effects due to holding the left VI constant became more and more apparent, the shorter the time scale. In choice relations across components, preference for the left key leveled off as the right key became leaner. Interfood choice approximated strict matching for the varied right key, whereas interfood choice hardly varied at all for the constant left key. At the shortest time scale, visit patterns differed for the left and right keys. Much evidence indicated the development of a fix‐and‐sample pattern. In sum, the procedural difference made a large difference to performance, except for choice at the longest time scale and the fix‐and‐sample pattern at the shortest time scale.
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