Kilohertz frequency alternating current (KHFAC) waveforms reversibly block conduction in mammalian peripheral nerves. The initiation of the KHFAC produces nerve activation, called the onset response, ...before complete block occurs. An amplitude ramp, starting from zero amplitude, is ineffective in eliminating this onset activity. We postulated that initiating the ramp from a non-zero amplitude would produce a different effect on the onset.
Experiments were conducted in an in vivo rat model. KHFAC was applied at supra block threshold amplitudes and then reduced to a lower sub block amplitude (25, 50, 75 and 90% of the block threshold amplitude). The amplitude was then increased again to the original supra block threshold amplitude with an amplitude ramp. This ramp time was varied for each of the amplitude levels tested.
The amplitude ramp was successful in eliminating a second onset. This was always possible for the ramps up from 75 and 90% block threshold amplitude, usually from 50% but never from 25% of the block threshold amplitude.
This maneuver can potentially be used to initiate complete nerve block, transition to partial block and then resume complete block without producing further onset responses.
•The block inception time for kiloHertz frequency alternating current nerve block has not been measured previously.•A novel method was created to extract the block inception time from muscle force ...measurements.•The block inception time was found to be on average 5 ms to 10 ms, with the most rapid inception being 2.5 ms to 5 ms.•Block inception times for KHFAC nerve block were significant more rapid than previously estimated.
Kilohertz frequency alternating currents (KHFAC) produce rapid nerve conduction block of mammalian peripheral nerves and have potential clinical applications in reducing nerve hyperactivity. However, there are no experimental measurements of the block inception time (BIT) for the complete block of mammalian motor axons, i.e. the time from the start of delivery of the KHFAC to the axons reaching a fully blocked state.
A “counted cycles” method (CCM) was designed to exploit characteristics of the onset response, which is typical of KHFAC block, to measure the BIT with a millisecond time resolution. Randomized and repeated experiments were conducted in an in-vivo rodent model, using trains of KHFAC over a range of complete cycle counts at three frequencies (10, 20, and 40 kHz).
Complete motor nerve conduction block was obtained in the rat sciatic nerve (N = 4) with an average BIT range of 5 ms–10 ms. The fastest BIT measured was 2.5 ms–5 ms. There was no statistical difference between the block inception times for the three frequencies tested.
There are no comparable methods to measure the KHFAC BIT.
The KHFAC BIT is faster than previously estimated. KHFAC motor nerve block is established in milliseconds. These results may assist in the design of methods to eliminate the onset response produced by KHFAC nerve block.
Intracortical microstimulation of the somatosensory cortex offers the potential for creating a sensory neuroprosthesis to restore tactile sensation. Whereas animal studies have suggested that both ...cutaneous and proprioceptive percepts can be evoked using this approach, the perceptual quality of the stimuli cannot be measured in these experiments. We show that microstimulation within the hand area of the somatosensory cortex of a person with long-term spinal cord injury evokes tactile sensations perceived as originating from locations on the hand and that cortical stimulation sites are organized according to expected somatotopic principles. Many of these percepts exhibit naturalistic characteristics (including feelings of pressure), can be evoked at low stimulation amplitudes, and remain stable for months. Further, modulating the stimulus amplitude grades the perceptual intensity of the stimuli, suggesting that intracortical microstimulation could be used to convey information about the contact location and pressure necessary to perform dexterous hand movements associated with object manipulation.
Many medical conditions are characterized by undesired or pathological peripheral neurological activity. The local delivery of high-frequency alternating currents (HFAC) has been shown to be a fast ...acting and quickly reversible method of blocking neural conduction and may provide a treatment alternative for eliminating pathological neural activity in these conditions. This work represents the first formal study of electrode design for high-frequency nerve block, and demonstrates that the interpolar separation distance for a bipolar electrode influences the current amplitudes required to achieve conduction block in both computer simulations and mammalian whole nerve experiments. The minimal current required to achieve block is also dependent on the diameter of the fibers being blocked and the electrode-fiber distance. Single fiber simulations suggest that minimizing the block threshold can be achieved by maximizing both the bipolar activating function (by adjusting the bipolar electrode contact separation distance) and a synergistic addition of membrane sodium currents generated by each of the two bipolar electrode contacts. For a rat sciatic nerve, 1.0-2.0 mm represented the optimal interpolar distance for minimizing current delivery.
Summary
This systematic review summarizes the effect of combined exercise and nutrition intervention on muscle mass and muscle function. A total of 37 RCTs were identified. Results indicate that ...physical exercise has a positive impact on muscle mass and muscle function in subjects aged 65 years and older. However, any interactive effect of dietary supplementation appears to be limited.
Introduction
In 2013, Denison et al. conducted a systematic review including 17 randomized controlled trials (RCTs) to explore the effect of combined exercise and nutrition intervention to improve muscle mass, muscle strength, or physical performance in older people. They concluded that further studies were needed to provide evidence upon which public health and clinical recommendations could be based. The purpose of the present work was to update the prior systematic review and include studies published up to October 2015.
Methods
Using the electronic databases MEDLINE and EMBASE, we identified RCTs which assessed the combined effect of exercise training and nutritional supplementation on muscle strength, muscle mass, or physical performance in subjects aged 60 years and over. Study selection and data extraction were performed by two independent reviewers.
Results
The search strategy identified 21 additional RCTs giving a total of 37 RCTs. Studies were heterogeneous in terms of protocols for physical exercise and dietary supplementation (proteins, essential amino acids, creatine, β-hydroxy-β-methylbuthyrate, vitamin D, multi-nutrients, or other). In 79% of the studies (27/34 RCTs), muscle mass increased with exercise but an additional effect of nutrition was only found in 8 RCTs (23.5%). Muscle strength increased in 82.8% of the studies (29/35 RCTs) following exercise intervention, and dietary supplementation showed additional benefits in only a small number of studies (8/35 RCTS, 22.8%). Finally, the majority of studies showed an increase of physical performance following exercise intervention (26/28 RCTs, 92.8%) but interaction with nutrition supplementation was only found in 14.3% of these studies (4/28 RCTs).
Conclusion
Physical exercise has a positive impact on muscle mass and muscle function in healthy subjects aged 60 years and older. The biggest effect of exercise intervention, of any type, has been seen on physical performance (gait speed, chair rising test, balance, SPPB test, etc.). We observed huge variations in regard to the dietary supplementation protocols. Based on the included studies, mainly performed on well-nourished subjects, the interactive effect of dietary supplementation on muscle function appears limited.
Aims.
A linear scaling of the mixed third-order moment of the magnetohydrodynamic (MHD) fluctuations is used to estimate the energy transfer rate of the turbulent cascade in the expanding solar wind.
...Methods.
In 1976, the Helios 2 spacecraft measured three samples of fast solar wind originating from the same coronal hole, at different distances from the Sun. Along with the adjacent slow solar wind streams, these intervals represent a unique database for studying the radial evolution of turbulence in samples of undisturbed solar wind. A set of direct numerical simulations of the MHD equations performed with the Lattice-Boltzmann code FLAME was also used for interpretation.
Results.
We show that the turbulence energy transfer rate decays approximately as a power law of the distance and that both the amplitude and decay law correspond to the observed radial temperature profile in the fast wind case. Results from MHD numerical simulations of decaying MHD turbulence show a similar trend for the total dissipation, suggesting an interpretation of the observed dynamics in terms of decaying turbulence and that multi-spacecraft studies of the solar wind radial evolution may help clarify the nature of the evolution of the turbulent fluctuations in the ecliptic solar wind.
Abstract
Funding Acknowledgements
Type of funding sources: Public grant(s) – EU funding. Main funding source(s): Hungarian National Research, Development and Innovation Fund
Introduction
...Smoke-induced diseases cause 20% of global mortality. The toxic agents of cigarette smoke have notorious destructive effects on the cardiovascular system. Therefore, many people use e-cigarettes instead of traditional tobacco products; yet, nicotine content remains the cause of addiction.
Purpose
Human induced pluripotent stem cells (hiPSC) provide a useful personalised link between clinical and in vitro cardiovascular models. Here we generated hiPSC lines from a pair of identical twins with diabetes to test long and short-term effects of nicotine.
Methods
Blood samples were used to reprogram mononuclear cell fractions into hiPSC via Sendai viral transduction of the Yamanaka factors (Cytotune 2.0). Genotype and pluripotency of the iPSC were checked with FACS, PCR, immunocytochemistry and embryoid body formation. hiPSC line from non-diabetic healthy control ("GM") was used as control. The hiPSC lines were differentiated into endothelial cells and used in a toxicology and phenotypic assays. hiPSC-derived endothelial cells and control HUVEC were treated with e-cigarette liquid with (nicotine 0.225 mg/ml, ECL18) and without nicotine (ECL0) or nicotine in culture medium (0.225 mg/ml). The cells were analysed with high content microscopy (HCS, Opera), using Hoechst, apoptotic marker caspase3/7, mitochondrial TMRM and endothelial CD31 labelling.
Results
On the clinical side, one of the diabetic twins was a smoker ("C") and diagnosed and treated with a severe coronary disease, whilst the other ("D") was a non-smoker and no coronary artery disease. For the reprogrammed twin clones (normal, 46XX chromosomes), no differences in exome sequence were found. Cells were positive for pluripotency marker SSEA4 (>90%, FACS); Oct4 and Nanog were also positive, embryoid body formation and PCR were positive for all the three germ layers. The phenotypic fidelity of hiPSC-derived endothelial cells (hiPSC-EC) were different from the twin lines. C cell line showed a higher endothelial-to-mesenchymal transition rate and non-endothelial drift as compared to D line at 3 passages FACS after CD31 isolation (9% CD31+ vs 37% and 41%, for C, D and non-diabetic control, respectively). Nicotine did not change TMRM or caspase 3/7 activation in "C" hiPSC-EC, in turn it induced apoptosis in "D" cells (p=0.01 vs ECL18 and p=0.02 vs EGM2+nicotine, n=3). In GM and HUVEC endothelial cells, TMRM intensity increased after e-cigarette liquid treatment (all p<0.05, n=3) and caspase was higher group with ECL containing nicotine (p = 0.0178, n=3).
"D" line endothelial cells showed higher cell loss to the nicotine diluted in EGM2, than in ECL (p = 0.0091, n=6).
Conclusions
Our developed a novel patient-specific hiPSC model where and in vitro toxicology assay showed alteration in endothelial phenotype associated with nicotine exposure. A scalable platform can provide further cohort level information on toxic agent like nicotine to the cardiovascular system.
Background Smokers have contact with many different types of health professionals. The impact of tobacco intervention by multiple types of heath professionals is not known. Methods and Materials As ...part of the 2003 Minnesota Adult Tobacco Survey, smokers ( n =1723) reported on tobacco treatment by medical doctors, nurses, dentists, pharmacists, or other health professionals. This analysis examined: (1) smokers’ report of tobacco intervention by different types of healthcare providers, (2) the proportion of smokers who report intervention by multiple provider types, and (3) the relationship between smokers’ report of intervention by multiple provider types and readiness to quit, quit attempts, and recent quitting. Results Among past-year smokers, 65% had visits with two or more types of health professionals. Among smokers who visited health professionals ( n =1523), only 34% reported being asked about smoking by two or more types of professionals. Among current smokers ( n =1324), advice or assistance from more than one type of professional was uncommon (26% and 7%, respectively). Being asked about smoking by two or more types of professionals substantially increased the odds of recent quitting (OR=2.37; 95% CI=1.15–4.88). Among current smokers, being advised to quit by two or more types of professionals increased the odds of having made a quit attempt in the past year (OR=2.92; 95% CI=1.56–5.45) or intending to quit in the next 6 months (OR=2.17; 95% CI=1.10–4.29). Conclusions Smoking-cessation interventions by more than one type of health professional have the potential to substantially increase quitting and readiness to quit in the population.
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