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Placebo Subjects (placebo + subject)
Selected AbstractsEffect of pulse repetition rate on the perception of thermal sensation with pulsed shortwave diathermyPHYSIOTHERAPY RESEARCH INTERNATIONAL, Issue 2 2000Charles Conor Murray Abstract Background and Purpose Pulsed shortwave diathermy (PSWD) is a form of therapy commonly used to enhance tissue repair and reduce pain. It is normally considered to be an athermal form of treatment; however, there is some evidence to suggest that thermal effects can arise with adequate dosage. The purpose of this study was to determine the pulse repetition rate (PRR) required to generate a ,possible' and ,definite' thermal sensation when PSWD was applied to the thigh. Method Thirty healthy subjects were randomly assigned to placebo or treatment groups. The treatment group was exposed to PSWD at a constant setting of pulse duration (400 µs) and pulse power (190 W) while the PRR was increased from 26 Hz to 400 Hz in 10 increments. Each dose was applied for a period of two minutes. At the end of each application, subjects were asked if they felt a (1) ,possible' or (2) ,definite' thermal sensation. Skin temperature was measured immediately after each application. Placebo subjects were exposed to PSWD at its lowest settings throughout the experiment (pulse power = 5W; pulse duration = 65 µs and PRR = 26 Hz). Results The results showed a significant correlation (p<0.048) between PRR at ,definite' thermal sensation and skin temperature post-treatment and PRR at ,possible' thermal sensation (p<0.001). Mean skin temperature increased significantly as PRR was increased, from 28.69 (±0.75) °C pre-treatment to 31.14 (±1.04) °C post-treatment, a mean difference of 2.34 °C. Conclusions These results suggest that PSWD at adequate dosages can generate thermal effects, and that there is a relationship between these thermal effects and the PRR used. These results may have significant implications for the safe use of PSWD in the clinical arena. Copyright © 2000 Whurr Publishers Ltd. [source] Acute alcohol impairs conditioning of a behavioural reward-seeking response and inhibitory control processes,implications for addictive disordersADDICTION, Issue 12 2009Sabine Loeber ABSTRACT Aims To investigate whether acute alcohol would affect performance of a conditioned behavioural response to obtain a reward outcome and impair performance in a task measuring inhibitory control to provide new knowledge of how the acute effects of alcohol might contribute to the transition from alcohol use to dependence. Design A randomized controlled between-subjects design was employed. Settings The laboratory of experimental psychology at the University of Sussex. Participants Thirty-two light to moderate social drinkers recruited from the undergraduate and postgraduate population. Measurements After the administration of alcohol (0.8 g/kg) or placebo participants underwent an instrumental reward-seeking procedure, with abstract stimuli serving as S+ (always predicting a win of 10 pence) and S, (always predicting a loss of 10 pence). In addition, a Stop Signal task was administered before and after the administration of alcohol. Findings Participants of the alcohol group performed the behavioural response to obtain the reward outcome more often than placebo subjects in trials associated with loss of money. This finding was observed, although alcohol was not affecting explicit knowledge of stimulus,response outcome contingencies and acquisition of conditioned attentional and emotional responses. In addition, alcohol increased Stop Signal reaction time indicating disinhibiting effects of alcohol, and this was associated positively with response probability to the S,. Conclusions These results demonstrate that alcohol is affecting inhibitory control of behavioural responses to external signals even when associated with punishment, contributing in this way to the transition from alcohol use to dependence. [source] Prevention of Postmenopausal Bone Loss by a Low-Magnitude, High-Frequency Mechanical Stimuli: A Clinical Trial Assessing Compliance, Efficacy, and Safety,JOURNAL OF BONE AND MINERAL RESEARCH, Issue 3 2004Clinton Rubin Abstract A 1-year prospective, randomized, double-blind, and placebo-controlled trial of 70 postmenopausal women demonstrated that brief periods (<20 minutes) of a low-level (0.2g, 30 Hz) vibration applied during quiet standing can effectively inhibit bone loss in the spine and femur, with efficacy increasing significantly with greater compliance, particularly in those subjects with lower body mass. Introduction: Indicative of the anabolic potential of mechanical stimuli, animal models have demonstrated that short periods (<30 minutes) of low-magnitude vibration (<0.3g), applied at a relatively high frequency (20,90 Hz), will increase the number and width of trabeculae, as well as enhance stiffness and strength of cancellous bone. Here, a 1-year prospective, randomized, double-blind, and placebo-controlled clinical trial in 70 women, 3,8 years past the menopause, examined the ability of such high-frequency, low-magnitude mechanical signals to inhibit bone loss in the human. Materials and Methods: Each day, one-half of the subjects were exposed to short-duration (two 10-minute treatments/day), low-magnitude (2.0 m/s2 peak to peak), 30-Hz vertical accelerations (vibration), whereas the other half stood for the same duration on placebo devices. DXA was used to measure BMD at the spine, hip, and distal radius at baseline, and 3, 6, and 12 months. Fifty-six women completed the 1-year treatment. Results and Conclusions: The detection threshold of the study design failed to show any changes in bone density using an intention-to-treat analysis for either the placebo or treatment group. Regression analysis on the a priori study group demonstrated a significant effect of compliance on efficacy of the intervention, particularly at the lumbar spine (p = 0.004). Posthoc testing was used to assist in identifying various subgroups that may have benefited from this treatment modality. Evaluating those in the highest quartile of compliance (86% compliant), placebo subjects lost 2.13% in the femoral neck over 1 year, whereas treatment was associated with a gain of 0.04%, reflecting a 2.17% relative benefit of treatment (p = 0.06). In the spine, the 1.6% decrease observed over 1 year in the placebo group was reduced to a 0.10% loss in the active group, indicating a 1.5% relative benefit of treatment (p = 0.09). Considering the interdependence of weight, the spine of lighter women (<65 kg), who were in the highest quartile of compliance, exhibited a relative benefit of active treatment of 3.35% greater BMD over 1 year (p = 0.009); for the mean compliance group, a 2.73% relative benefit in BMD was found (p = 0.02). These preliminary results indicate the potential for a noninvasive, mechanically mediated intervention for osteoporosis. This non-pharmacologic approach represents a physiologically based means of inhibiting the decline in BMD that follows menopause, perhaps most effectively in the spine of lighter women who are in the greatest need of intervention. [source] A Randomized, Double-Blind, Pharmacokinetic Study of Oral Maribavir with Tacrolimus in Stable Renal Transplant RecipientsAMERICAN JOURNAL OF TRANSPLANTATION, Issue 10 2009M. D. Pescovitz Maribavir is being developed as a novel agent for the prevention or treatment of cytomegalovirus infections after stem cell and organ transplantation. This was a randomized, double-blind, placebo-controlled study designed to evaluate the potential pharmacokinetic interaction of concomitant administration of maribavir and tacrolimus. Twenty-five adult renal transplant recipients with stable renal function and stable dosing regimens of tacrolimus were randomized (20 maribavir 400 mg p.o. q12 h: 5 placebo). Tacrolimus whole blood concentration profiles were determined before and after 7 days of co-administration with maribavir. When co-administered with maribavir, tacrolimus mean Cmax increased 38%, tacrolimus trough concentrations (12 h post-dose) increased 57% and tacrolimus AUC(0-,) increased 51%. Apparent oral clearance of tacrolimus decreased 34% and Tmax was delayed by 0.5 h. There were no serious adverse events and no subject prematurely discontinued treatment. Because of the limited 7-day dosing course, the adverse event profile could not be adequately assessed. However, as seen with other maribavir studies, dysgeusia was common (90% of maribavir subjects and 20% of placebo subjects). In conclusion, co-administration of maribavir 400 mg twice daily increases exposure to tacrolimus. Routine therapeutic drug monitoring of tacrolimus blood concentrations should be included both at initiation and completion of maribavir treatment. [source] | ||||||||||