Reward, performance, and the response strength method in self-stimulating rats: validation and neuroleptics

The response strength method consists of exposing the subject to a series of variable interval schedules of reinforcement at differing densities. Response rate is plotted against obtained reinforcement rate for each schedule. The data conform to a negatively accelerated curve that is fit well by an analytical representation which contains two parameters. The values of these parameters are obtained from the fitted curve, and are suggested to independently reflect reinforcement and performance functions. In a first experiment, two manipulations were conducted that validated these suggestions. First, lowering the frequency of brain stimulation pulses induced a relatively selective shift in the reinforcement parameter. Second, increasing the force required to press the lever primarily altered the performance parameter. In a second experiment, the effects of neuroleptic administration on these two parameters were noted and compared to the results of the first experiment. In general, neuroleptics were seen to produce both reward and motor/performance impairments in self-stimulating rats.     

两种正畸釉质粘合剂粘结强度的比较研究

目的：比较两种正畸粘合剂与釉质的粘结强度。方法：选择拔除新鲜无龋上颌第三磨牙，在其上制备粘结面，与圆柱状粘合剂粘结，测定剪切强度，并在扫描电镜（SEM）下观察残留树脂突。结果：两种粘合剂的剪切强度无显著性差异；在牙体粘结面上均可见残留的树脂突。结论：两种粘合剂均可用于正畸粘结。     

Lack of variation in muscle strength with menstrual status in healthy women aged 45–54 years: data from a national survey

Isometric handgrip, quadriceps muscle strength and leg extensor power were assessed as part of a large representative survey of adult men and women in England. The gender ratios for these muscle strength measurements did not differ across age groups, which ranged from 25 to 65 years. Data from a subsample of women who were aged between 45 and 54 years and free of major health problems or current gynaecological problems (n = 299) and were analysed to see if there were differences in the muscle measurements according to reported menstrual status. Analysis of variance was used to compare four subgroups of women as follows: those who were still menstruating regularly (n = 89), those who had stopped altogether (n = 92), those who were irregular (n = 33) and those on hormone replacement therapy (n = 15). No significant differences were found between these subgroups in any of the three muscle measurements, body mass, fat-free mass (derived from four skinfolds), body mass index, or customary activity levels. There was a significant age difference of 2 years between two subgroups. After having controlled for this, using analysis of covariance, the outcome was not changed. These women were also compared with men in the same age range; the women had about 60% of the strength of the men and a highly significant difference remained after controlling for fat-free mass in all subgroups. No evidence was found for an ergogenic effect of the high oestrogen status conferred by natural mensturation or hormone replacement therapy.     

Effect of helium-neon and infrared laser irradiation on wound healing in rabbits

We examined the biostimulating effects of helium-neon laser radiation (HeNe; 632.8 nm), pulsed infrared laser radiation (IR; 904 nm), and the two combined on skin wound healing in New Zealand white rabbits. Seventy-two rabbits received either 1) no exposure, 2) 1.65 J/cm2 HeNe, 3) 8.25 J/cm2 pulsed IR, or 4) both HeNe and IR together to one of two dorsal full-thickness skin wounds, daily, for 21 days. Wound areas were measured photographically at periodic intervals. Tissue samples were analyzed for tensile strength, and histology was done to measure epidermal thickness and cross-sectional collagen area. Significant differences were found in the tensile strength of all laser-treated groups (both the irradiated and nonirradiated lesion) compared to group 1. No differences were found in the rate of wound healing or collagen area. Epidermal growth was greater in the HeNe-lased area compared to unexposed tissue, but the difference was not significant. Thus, laser irradiation at 632.8 nm and 904 nm alone or in combination increased tensile strength during wound healing and may have released tissue factors into the systemic circulation that increased tensile strength on the opposite side as well.     

The effect of systemic corticosteroid therapy on the breaking strength of skin

Summary It was noted clinically that patients under long-term steroid treatment were susceptible to avulsion injuries following minor trauma. Laboratory experiment in mice revealed significant reduction in the breaking strength following steroids therapyThe authors dedicate this paper to the dear memory of Prof. Z. Neuman, M.D., F.A.C.S. former Chairman of the department of Plastic and Maxillofacial Surgery, who passed away on March 22, 1977     

Effects of physical exercise on fall risk factors in elderly at home in intervention trial

Objective In this study, we used an intervention approach to examine the effects of physical exercise on elderly people living at home in a rural area. Methods Two regions in a village were randomly assigned as the control and intervention regions. The subjects were 60 years of age or older and were able to carry out their activities of daily living independently. The numbers of subjects were 56 and 81 for the control and intervention regions, respectively. In the control region, lectures on health were provided twice. In the intervention region, instructions on ten types of physical exercise were provided six times during this three-month study. In addition, the subjects in the intervention region were instructed to do, exercises by themselves at home three days per week. The effects were compared by evaluating motor functions in maximum step length, 10-m full-power walking parameters, right knee extension torque, right hip flexion torque, and stepping time on a 40-cm staircase; data were obtained before and after the intervention. Results Analysis of covariance (ANCOVA) showed significant improvements in right maximum step length, the mean of the right and left maximum step lengths, and right hip flexion torque in the intervention region. Conclusion The three-month physical exercise program improves the motor functions of the elderly.     

Physical capacity in relation to low back, neck, or shoulder pain in a working population

Aims

To investigate the longitudinal relation between physical capacity (isokinetic lifting strength, static endurance of the back, neck, and shoulder muscles, and mobility of the spine) and low back, neck, and shoulder pain.

Methods

In this prospective cohort study, 1789 Dutch workers participated. At baseline, isokinetic lifting strength, static endurance of the back, neck, and shoulder muscles, and mobility of the spine were measured in the pain free workers, as well as potential confounders, including physical workload. Low back, neck, and shoulder pain were self‐reported annually at baseline and three times during follow up.

Results

After adjustment for confounders, Poisson generalised estimation equations showed an increased risk of low back pain among workers in the lowest sex specific tertile of performance in the static back endurance tests compared to workers in the reference category (RR = 1.42; 95% CI 1.19 to 1.71), but this was not found for isokinetic trunk lifting strength or mobility of the spine. An increased risk of neck pain was shown for workers with low performance in tests of isokinetic neck/shoulder lifting strength (RR = 1.31; 95% CI 1.03 to 1.67) and static neck endurance (RR = 1.22; 95% CI 1.00 to 1.49). Among workers in the lowest tertiles of isokinetic neck/shoulder lifting strength or endurance of the shoulder muscles, no increased risk of shoulder pain was found.

Conclusions

The findings of this study suggest that low back or neck endurance were independent predictors of low back or neck pain, respectively, and that low lifting neck/shoulder strength was an independent predictor of neck pain. No association was found between lifting trunk strength, or mobility of the spine and the risk of low back pain, nor between lifting neck/shoulder strength or endurance of the shoulder muscles and the risk of shoulder pain.     

A New Method for Measuring Motor Block in the Lower Extremities

A method for determining muscle strength in the lower extremities was developed and its clinical application evaluated in ten elderly, healthy subjects, and also subsequently in one of them during spinal anaesthesia. With the subject lying in the lithotomy position on a modified operating table, muscle strength measurements were made during flexion of the hip, extension of the knee and plantar flexion of the big toe. The electromechanical performance of the apparatus was stable, and the maximum measurement errors observed at loads of 245 and 49 N were 4 and 11% of the deflections, respectively. The subjects underwent repeated muscle strength measurements during a 4-h period without any difficulty. No signs of muscular fatigue were observed. The variation of the measured isometric muscle strength was small and the average coefficient of variation roughly 10%. In the patient receiving spinal anaesthesia, the degree of motor block was determined, and the results are presented graphically. This new method for evaluation of motor block in the lower extremities is a reliable quantitative method for bilateral, three-joint muscle strength measurements, which is also applicable during regional anaesthesia.