Ischemic preconditioning improves maximal performance in humans

Repeated episodes of ischemia followed by reperfusion, commonly referred to as ischemic preconditioning (IPC), represent an endogenous protective mechanism that delays cell injury. IPC also increases blood flow and improves endothelial function. We hypothesize that IPC will improve physical exercise performance and maximal oxygen consumption. The purpose of the study was to examine the effect of ischemic preconditioning in leg skeletal muscles on cycling exercise performance in healthy individuals. Fifteen healthy, well-trained subjects performed two incremental maximal exercise tests on a bicycle ergometer. Power output, oxygen consumption, ventilation, respiratory quotient, and heart rate were measured continuously. Blood pressure and blood lactate were measured before and after the test. One exercise test was performed after the application of ischemic preconditioning, using a protocol of three series of 5-min ischemia at both legs with resting periods of 5 min in between. The other maximal cycling test served as a control. Tests were conducted in counterbalanced order, at least 1 week apart, at the same time of the day. The repeated ischemic periods significantly increased maximal oxygen consumption from 56.8 to 58.4 ml/min per kg (P = 0.003). Maximal power output increased significantly from 366 to 372 W (P = 0.05). Ischemic preconditioning had no effect on ventilation, respiratory quotient, maximal heart rate, blood pressure or on blood lactate. Repeated short-term leg ischemia prior to an incremental bicycle exercise test improves maximal oxygen consumption by 3% and power output by 1.6%. This protocol, which is suggested to mimic the effects of ischemic preconditioning, may have important implications for exercise performance

Principles of Hand Fracture Management

The hand is essential in humans for physical manipulation of their surrounding environment. Allowing the ability to grasp, and differentiated from other animals by an opposing thumb, the main functions include both fine and gross motor skills as well as being a key tool for sensing and understanding the immediate surroundings of their owner

Post-synthetic Ti Exchanged UiO-66 Metal-Organic Frameworks that Deliver Exceptional Gas Permeability in Mixed Matrix Membranes

Gas separation membranes are one of the lowest energy technologies available for the separation of carbon dioxide from flue gas. Key to handling the immense scale of this separation is maximised membrane permeability at sufficient selectivity for CO2 over N2. For the first time it is revealed that metals can be post-synthetically exchanged in MOFs to drastically enhance gas transport performance in membranes. Ti-exchanged UiO-66 MOFs have been found to triple the gas permeability without a loss in selectivity due to several effects that include increased affinity for CO2 and stronger interactions between the polymer matrix and the Ti-MOFs. As a result, it is also shown that MOFs optimized in previous works for batch-wise adsorption applications can be applied to membranes, which have lower demands on material quantities. These membranes exhibit exceptional CO2 permeability enhancement of as much as 153% when compared to the non-exchanged UiO-66 mixed-matrix controls, which places them well above the Robeson upper bound at just a 5 wt.% loading. The fact that maximum permeability enhancement occurs at such low loadings, significantly less than the optimum for other MMMs, is a major advantage in large-scale application due to the more attainable quantities of MOF needed

Enhanced selectivity in mixed matrix membranes for CO2 capture through efficient dispersion of amine-functionalized MOF nanoparticles

Mixed matrix membranes (MMMs) for gas separation applications have enhanced selectivity when compared with the pure polymer matrix, but are commonly reported with low intrinsic permeability, which has major cost implications for implementation of membrane technologies in large-scale carbon capture projects. High-permeability polymers rarely generate sufficient selectivity for energy-efficient CO2 capture. Here we report substantial selectivity enhancements within high-permeability polymers as a result of the efficient dispersion of amine-functionalized, nanosized metal–organic framework (MOF) additives. The enhancement effects under optimal mixing conditions occur with minimal loss in overall permeability. Nanosizing of the MOF enhances its dispersion within the polymer matrix to minimize non-selective microvoid formation around the particles. Amination of such MOFs increases their interaction with thepolymer matrix, resulting in a measured rigidification and enhanced selectivity of the overall composite. The optimal MOF MMM performance was verified in three different polymer systems, and also over pressure and temperature ranges suitable for carbon capture

Variation in the immune response to adenoviral vectors in the brain: influence of mouse strain, environmental conditions and priming

E1-deleted adenoviral vectors expressing the bacterial β-galactosidase gene were inoculated into the brain of unprimed and primed C3H.He or C57BL/6J mice housed under either conventional or specific-pathogen-free (SPF) conditions. The kinetics of immune responses to both the vector and the transgene were investigated. In mice previously sensitized to adenovirus, the leukocyte infiltrate in the brain was dominated by CD8+ T cells, whereas in unprimed mice CD4+ T cells were present at higher levels. As expected, antibody titres to both adenovirus and β-galactosidase were higher in primed mice than in unprimed mice after intracranial inoculation. C3H.He mice consistently made higher antibody responses than C57BL/6J mice. Although adenoviral vectors induced an inflammatory response under all conditions, mice housed in SPF facilities exhibited less inflammation than conventional mice and transgene expression persisted for longer. Irrespective of whether the mice had been deliberately primed to adenovirus, antibody titres were consistently lower in SPF mice compared with conventional mice. This study clearly demonstrates that environmental conditions, as well as previous priming to adenovirus, will affect both the quality and duration of the immune response triggered by gene delivery to the brain.</p

Variation in the immune response to adenoviral vectors in the brain: influence of mouse strain, environmental conditions and priming.

E1-deleted adenoviral vectors expressing the bacterial beta-galactosidase gene were inoculated into the brain of unprimed and primed C3H.He or C57BL/6J mice housed under either conventional or specific-pathogen-free (SPF) conditions. The kinetics of immune responses to both the vector and the transgene were investigated. In mice previously sensitized to adenovirus, the leukocyte infiltrate in the brain was dominated by CD8+ T cells, whereas in unprimed mice CD4+ T cells were present at higher levels. As expected, antibody titres to both adenovirus and beta-galactosidase were higher in primed mice than in unprimed mice after intracranial inoculation. C3H.He mice consistently made higher antibody responses than C57BL/6J mice. Although adenoviral vectors induced an inflammatory response under all conditions, mice housed in SPF facilities exhibited less inflammation than conventional mice and transgene expression persisted for longer. Irrespective of whether the mice had been deliberately primed to adenovirus, antibody titres were consistently lower in SPF mice compared with conventional mice. This study clearly demonstrates that environmental conditions, as well as previous priming to adenovirus, will affect both the quality and duration of the immune response triggered by gene delivery to the brain

The complementary roles of deletion and regulation in transplantation tolerance

Neonatal tolerance of alloantigens was described in mice nearly half a century ago, but unfortunately, the translation of these early findings into the clinical arena proved to be much more challenging than was first anticipated. However, the past decade has seen considerable progress in our understanding of the mechanisms that contribute to transplantation tolerance in experimental models. This review outlines our current understanding of the mechanisms of allograft tolerance, emphasizing the complementary roles of deletion and regulation of alloreactive T cells. [References: 145