Novel pyridinium surfactants for efficient, nontoxic in vitro gene delivery

Novel, double-chained pyridinium compounds have been developed that display highly efficient DNA transfection properties. The transfection efficiency of several of these compounds is enhanced by an order of magnitude, when compared with the transfection efficiency accomplished with the widely used cationic lipid system, lipofectin. Most importantly, the pyridinium compounds were found to be essentially nontoxic toward cells. Using various reporter genes, such as beta-galactosidase and pNEO (a gene construct that renders cells resistent to antibiotic derivatives of neomycin like G418), we demonstrate that the enhanced efficiency relates to the fact that a relative higher number of cells in the population is transfected (approximately 50% in the case of COS cells) by the pyridinium derivatives, whereas the delivery of DNA per cell is also enhanced. Furthermore, application of the pyridinium derivatives shows little cellular preference in their ability to transfect cells. By systematically modifying the structure of the pyridinium amphiphile, i.e., by changing either the headgroup structure or the alkyl chains, some insight was obtained that may lead to unraveling the mechanism of amphiphile-mediated transfection, and thus to protocols that further optimize the carrier properties of the amphiphile. Our results reveal that unsaturated alkyl chains enhance the transfection properties of the pyridinium-based amphiphiles. Preliminary experiments suggest that the structure-dependent improvement of transfection efficiency, when comparing pyridinium derivatives with lipofectin, likely relates to the mechanism of delivery rather than the packaging of the amphiphile/DNA complex

Effects of asymmetrical support on lower limb muscle activity during Lokomat guided gait in persons with a chronic stroke:an explorative study

BACKGROUND: The Lokomat, one of the most popular robotic exoskeletons, can take the asymmetry in the gait pattern of unilaterally affected patients into account with its opportunity to provide unequal levels of movement support (or 'guidance') to each of the legs. This asymmetrical guidance may be used to selectively unburden limbs with impaired voluntary control and/or to exploit the interlimb couplings for training purposes. However, there is a need to explore and understand these specific device opportunities more broadly before implementing them in training. AIM: The aim of this study was to explore the effects of (a)symmetrical guidance settings on lower limb muscle activity in persons with post stroke hemiparesis, during Lokomat guided gait. DESIGN: A single group, dependent factorial design. SETTING: Rehabilitation center; a single session of Lokomat guided walking. POPULATION: A group of ten persons with post stroke hemiparesis. METHODS: Participants walked in the Lokomat in eight conditions, consisting of symmetrical and asymmetrical guidance situations, at both 0.28 m/s and 0.56 m/s. During symmetrical conditions, both legs received 30% or 100% guidance, while during asymmetrical conditions one leg received 30% and the other leg 100% guidance. Surface electromyography was bilaterally measured from: Biceps Femoris, Rectus Femoris, Vastus Medialis, Medial Gastrocnemius and Tibialis Anterior. Statistical effects were assessed using Statistical Parametric Mapping. RESULTS: The provision of assymetrical guidance did not affect the level of lower limb muscle activity. In addition, no effect (except for Vastus Medialis in the affected leg during 1.5-2.4% of the gait cycle) of symmetrical guidance on muscle amplitude could be observed. CONCLUSIONS: The results show no evidence that either symmetrical or asymmetrical guidance settings provided by the Lokomat can be used to manipulate activity of lower limb musculature in persons with post stroke hemiparesis. CLINICAL REHABILITATION IMPACT: This study provides insights for the use of specific opportunities provided by the Lokomat for training purposes post stroke

Lokomat guided gait in hemiparetic stroke patients:the effects of training parameters on muscle activity and temporal symmetry

Purpose: The Lokomat is a commercially available robotic gait trainer, applied for gait rehabilitation in post-stroke hemiparetic patients. Selective and well-dosed clinical use of the Lokomat training parameters, i.e. guidance, speed and bodyweight support, requires a good understanding of how these parameters affect the neuromuscular control of post-stroke hemiparetic gait. Materials and methods: Ten stroke patients (unilateral paresis, 7 females, 64.5 ± 6.4 years, >3months post-stroke, FAC scores 2–4)) walked in the Lokomat under varying parameter settings: 50% or 100% guidance, 0.28 or 0.56m/s, 0% or 50% bodyweight support. Electromyography was recorded bilaterally from Gluteus Medius, Biceps Femoris, Vastus Lateralis, Medial Gastrocnemius, and Tibialis Anterior. Pressure sensors placed under the feet were used to determine the level of temporal gait symmetry. Results: Varying guidance and bodyweight support had little effect on muscle activity, but increasing treadmill speed led to increased activity in both the affected (Biceps Femoris, Medial Gastrocnemius, Tibialis Anterior) and unaffected leg (all muscles). The level of temporal symmetry was unaffected by the parameter settings. Conclusions: The Lokomat training parameters are generally ineffective in shaping short term muscle activity and step symmetry patients with hemiparetic stroke, as speed is the only parameter that significantly affects muscular amplitude. Trial Registration: d.n.a.IMPLICATIONS FOR REHABILITATIONThe Lokomat is a commercially available gait trainer that can be used for gait rehabilitation in post-stroke hemiparetic patients.This study shows that muscle amplitude is generally low during Lokomat guided walking, and that treadmill Speed is the main training parameter to influence muscular output in stroke patients during Lokomat walking.Varying Guidance and Bodyweight Support within a clinical relevant range barely affected muscle activity, and temporal step symmetry was unaffected by variation in any of the training parameters.Based on the findings it is advised to increase speed as early as possible during Lokomat therapy, or use other means (e.g. feedback or instructions) to stimulate active involvement of patients during training. The Lokomat is a commercially available gait trainer that can be used for gait rehabilitation in post-stroke hemiparetic patients. This study shows that muscle amplitude is generally low during Lokomat guided walking, and that treadmill Speed is the main training parameter to influence muscular output in stroke patients during Lokomat walking. Varying Guidance and Bodyweight Support within a clinical relevant range barely affected muscle activity, and temporal step symmetry was unaffected by variation in any of the training parameters. Based on the findings it is advised to increase speed as early as possible during Lokomat therapy, or use other means (e.g. feedback or instructions) to stimulate active involvement of patients during training.</p

Training for the HandbikeBattle:an explorative analysis of training load and handcycling physical capacity in recreationally active wheelchair users

Purpose: (1) to analyze training characteristics of recreationally active wheelchair users during handcycle training, and (2) to examine the associations between training load and change in physical capacity. Methods: Former rehabilitation patients (N = 60) with health conditions such as spinal cord injury or amputation were included. Participants trained for five months. A handcycling/arm crank graded exercise test was performed before and after the training period. Outcomes: peak power output per kg (POpeak/kg) and peak oxygen uptake per kg (VO 2peak/kg). Training load was defined as Training Impulse (TRIMP), which is rating of perceived exertion (sRPE) multiplied by duration of the session, in arbitrary units (AU). Training intensity distribution (TID) was also determined (time in zone 1, RPE ≤4; zone 2, RPE 5–6; zone 3, RPE ≥7). Results: Multilevel regression analyses showed that TRIMP sRPE was not significantly associated with change in physical capacity. Time in zone 2 (RPE 5–6) was significantly associated with ΔVO 2peak, %ΔVO 2peak, ΔVO 2peak/kg and %ΔVO 2peak/kg. Conclusion: Training at RPE 5–6 was the only determinant that was significantly associated with improvement in physical capacity. Additional controlled studies are necessary to demonstrate causality and gather more information about its usefulness, and optimal handcycle training regimes for recreationally active wheelchair users.IMPLICATIONS FOR REHABILITATION Monitoring of handcycle training load is important to structure the training effort and intensity over time and to eventually optimize performance capacity. This is especially important for relatively untrained wheelchair users, who have a low physical capacity and a high risk of overuse injuries and shoulder pain. Training load can be easily calculated by multiplying the intensity of the training (RPE 0–10) with the duration of the training in minutes. Results on handcycle training at RPE 5–6 intensity in recreationally active wheelchair users suggests to be promising and should be further investigated with controlled studies

Secondary health conditions in persons with a spinal cord injury for at least 10 years:design of a comprehensive long-term cross-sectional study

Purpose: To describe the prevalence of secondary health conditions (SHCs) (urinary tract and bowel problems, pressure ulcers, spasticity, musculoskeletal and neuropathic pain, sexual dysfunction, respiratory and cardiovascular disorders) in persons with long-term spinal cord injury (SCI), and to explore the impact of SHCs on fitness, active lifestyle, participation and well-being. Methods: A time since injury (TSI)-stratified cros-ssectional study among 300 persons between 28- and 65-year-old with a SCI for at least 10 years. Strata of TSI are 10-19, 20-29, and 30 or more years. All eight Dutch rehabilitation centres with a SCI unit will participate. Participants will be invited for a 1-day visit to the rehabilitation centre for an aftercare check-up by the local SCI rehabilitation physician (neurological impairment, SHCs and management), physical tests by a trained research assistant (lung function, wheelchair skills, physical capacity), and they will be asked to complete a self-report questionnaire in advance. Results: Not applicable. Conclusion: This study will provide knowledge on the health status and functioning of persons aging with SCI living in the Netherlands. This knowledge will help us to develop predictive models for the occurrence of SHCs and to formulate guidelines to improve health care for persons with long-term SCI.</p

Anaerobic exercise testing in rehabilitation:A systematic review of available tests and protocols

Objective: Anaerobic capacity assessment in rehabilitation has received increasing scientific attention in recent years. However, anaerobic capacity is not tested consistently in clinical rehabilitation practice. This study reviews tests and protocols for anaerobic capacity in adults with various disabilities (spinal cord injury, cerebral palsy, cerebral vascular accident, lower-limb amputation(s)) and (able-bodied) wheelchair users. Data sources: PubMed, CINAHL and Web of Science. Study selection: Papers were screened by 2 independent assessors, and were included when anaerobic exercise tests were performed on the above-selected subject groups. Data extraction: Included articles were checked for methodological quality. Data synthesis: A total of 57 papers was included. Upper-body testing [56 protocols] was conducted with arm crank [16] and wheelchair tests [40]. With a few [2] exceptions, modified Wingate (Wingate) protocols and wheelchair sprint tests dominated upper-body anaerobic testing. In lower-body anaerobic work [11], bicycle [3] and recumbent [1], and overground tests [7] were used, in which Wingate, sprint or jump protocols were employed. Conclusion: When equipment is available a Wingate protocol is advised for assessment of anaerobic capacity in rehabilitation. When equipment is not avail-able a 20-45 s sprint test is a good alternative. Future research should focus on standardized tests and protocols specific to different disability groups

Separabelized Skyrme Interactions and Quasiparticle RPA

A finite rank separable approximation for the quasiparticle RPA with Skyrme interactions is applied to study the low lying quadrupole and octupole states in some S isotopes and giant resonances in some spherical nuclei. It is shown that characteristics calculated within the suggested approach are in a good agreement with available experimental data.Comment: 12 pages, 2 figures, proceedings of the Seventh School-Seminar on Heavy Ion Physics, Dubna, Russia, May 27-June 1, 2002; to appear in Physics of Atomic Nucle

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Nonadherence to medical therapy is frequently encountered in patients with inflammatory bowel disease (IBD). We aimed to identify predictors for future (non)adherence in IBD

Quasiparticle RPA with finite rank approximation for Skyrme interactions

A finite rank separable approximation for the particle-hole RPA calculations with Skyrme interactions is extended to take into account the pairing. As an illustration of the method energies and transition probabilities for the quadrupole and octupole excitations in some O, Ar, Sn and Pb isotopes are calculated. The values obtained within our approach are very close to those that were calculated within QRPA with the full Skyrme interaction. They are in reasonable agreement with experimental data.Comment: 20 pages, 1 figure, submitted to Phys.Rev.