Comparison of lower limb stiffness between male and female dancers and athletes during drop jump landings

Repetition of jumps in dance and sport training poses a potential injury risk; however, non‐contact landing injuries are more common in athletes than dancers. This study aimed to compare the lower limb stiffness characteristics of dancers and athletes during drop landings to investigate possible mechanisms of impact‐related injuries. Kinematics and kinetics were recorded as 39 elite modern and ballet dancers (19 men and 20 women) and 40 college‐level team sport athletes (20 men and 20 women) performed single‐legged drop landings from a 30‐cm platform. Vertical leg stiffness and joint stiffness of the hip, knee, and ankle were calculated using a spring‐mass model. Stiffness data, joint kinematics, and moments were compared with a group‐by‐sex 2‐way analysis of variance. Multiple linear regression was used to assess the relative contribution of hip and knee and ankle joint stiffness to variance in overall vertical leg stiffness for dancers and athletes. Dancers had lower leg (P < 0.001), knee joint (P = 0.034), and ankle joint stiffness (P = 0.043) than athletes. This was facilitated by lower knee joint moments (P = 0.012) and greater knee (P = 0.029) and ankle joint (P = 0.048) range of motion in dancers. Males had higher leg (P < 0.001) and ankle joint stiffness (P < 0.001) than females. This occurred through lower ankle range of motion (P < 0.001) and greater ankle moment (P = 0.022) compared to females. Male and female dancers demonstrated reduced lower limb stiffness compared to athletes, indicating a more pliable landing technique. Dance training techniques could potentially inform approaches to injury prevention in athletes.     

Autistic Traits Moderate Reappraisal Success for Depression and Anxiety Symptoms

Journal of Autism and Developmental Disorders - Cognitive reappraisal is associated with reduced emotional distress; however, little is known about the nature of this relationship in autism. This...     

Geriatric nurse involvement during intra-hospital transitions

Geriatric nurses are skilled in the special needs of hospitalized older adults. While significant focus has been placed on improving care transitions upon discharge, less attention has been placed on intra-hospital transitions. Intra-hospital transitions represent transfers occurring between hospital units or rooms. Intra-hospital transitions challenge normal nursing workflow and require careful consideration of care coordination to prevent adverse events for older adults. Frequent changes in environment and a lack of consistency in care may support the development or prolongation of delirium as older adults are transferred between units and rooms. Additional adverse event risks include infections and falls, which also increases with each transfer. Geriatric nurse involvement can enhance communication between units as well as ensuring appropriate geriatric assessments occur. Geriatric nurses are thus well positioned to act as leaders during intra-hospital transitions, potentially reducing these and adverse events.     

Environmental stimuli promote the acquisition of nicotine self-administration in rats

RATIONALE: Environmental stimuli associated with drugs of abuse are believed to play a major role in the motivation to take drugs, drug dependence, and relapse. Previous work from this laboratory demonstrated that the response-contingent presentation of drug-related, visual cues was at least as important as nicotine in the maintenance, extinction and reacquisition of self-administration in experienced rats. OBJECTIVES: In the present research, we asked whether these same visual cues are effective in promoting the acquisition of operant responding in drug naive rats. METHODS: Male Sprague-Dawley rats were tested for self-administration of IV nicotine (0.03 mg/kg, free base) in 1-h daily sessions when infusions were or were not paired with two lighting events: a 1-s cue light, followed by a 1-min period during which the chamber light was turned off and responding was not reinforced. RESULTS: Rats tested with cues plus nicotine rapidly acquired self-administration and increased their lever pressing rates as the schedule progressed from FR1 to FR5. Without cues, the rate of nicotine self-administration was low and no adjustments were made in response to increasing schedule demands. While one of the stimuli, turning off the chamber light, was shown to have primary reinforcing properties, its association with nicotine produced a synergistic enhancement of lever pressing. Acquisition of operant responding was also enhanced, but to a lesser extent, by a previously neutral compound stimulus, i.e. the nicotine-paired cue light presented with a 1-s tone. CONCLUSIONS: These results illustrate a powerful interaction between environmental stimuli and nicotine in the acquisition of operant responding and indicate that both intrinsically reinforcing and previously neutral cues can participate in this effect.     

Behavioral and neurochemical sensitization to amphetamine following early postnatal administration of methylmercury (MeHg)

Perinatal exposure to methylmercury (MeHg) in rodents has been linked to changes in sensitivity to dopaminergic agents later in life. In an effort to determine the behavioral and neurochemical response to the indirect dopaminergic and serotonergic agonist amphetamine following neonatal exposure to MeHg, male BALB/c mice were administered MeHg during critical periods of neural development and challenged with amphetamine as adults. Mice were observed 15, 30 and 60 min after a single amphetamine injection (7.5 mg/kg i.p.) for presence of stereotypic and self-injurious behaviors, abnormal posture, and hyperthermia. Mice treated with 2 or 4 mg/kg MeHg on alternate days 3-15 of life demonstrated an increase in body temperature and the appearance of stereotypic and self-injurious behaviors not observed when amphetamine was administered to either vehicle-exposed mice or those treated with an equivalent total amount of MeHg administered on postnatal days 13 and 15. Neurochemical analysis of MeHg- and vehicle-exposed mice challenged with amphetamine or saline revealed alterations in dopaminergic and serotonergic activity which corresponded to the sensitized behavioral response to amphetamine. These observations demonstrate a critical window for MeHg exposure affecting the later appearance of amphetamine-induced self-injurious behavior and support the hypothesis that early exposure to environmental neurotoxicants may predispose individuals to engage in aberrant, intrusive behaviors later in life.     

Avoidance Responding Following Amphetamine‐Induced Dopamine Depletion

The effect of an amphetamine‐induced depletion of striatal dopamine on active and passive avoidance responding of rats was examined. Sixteen animals received two sets of 4 injections each of 15 mg/kg d‐amphetamine, administered at 2 hr intervals with each set delivered one week apart. One week after the last injection, animals were given 50 consecutive active avoidance trials in a shuttle box. Animals treated with amphetamine exhibited a 50% depletion of striatal dopamine and showed a slower learning curve, as evidenced by significantly fewer avoidances and a slower escape latency during trials 21–30. Both groups demonstrated a 90% avoidance rate by trials 41–50. A separate group of rats was treated as above and trained for several weeks on the active avoidance procedure. Haloperidol (0.01–0.10 mg/kg intraperitoneally) dose‐dependently decreased avoidance number and increased avoidance and escape latency in both groups, an effect that was exaggerated in those animals previously treated with amphetamine. Finally, these animals were tested in the same apparatus using a passive avoidance procedure. The amphetamine treatment produced a significantly higher mean number of avoidances in this procedure compared to saline‐treated animals during trials 1–20. These results suggest that the impairment in conditioned avoidance following amphetamine treatment is due to a motoric, rather than a cognitive deficit.