The Influence of Visual, Vestibular, and Hindlimb Proprioceptive Ablations on Landing Preparation in Cane Toads.

Coordinated landing from a jump requires preparation, which must include appropriate positioning and configuration of the landing limbs and body to be successful. While well studied in mammals, our lab has been using the cane toad (Rhinella marinus) as a model for understanding the biomechanics of controlled landing in anurans, animals that use jumping or bounding as their dominant mode of locomotion. In this article, we report new results from experiments designed to explore how different modes of sensory feedback contribute to previously identified features of coordinated landing in toads. More specifically, animals in which vision, hindlimb proprioception, or vestibular feedback were removed, underwent a series of hopping trials while high-speed video was used to record and characterize limb movements and electromyographic (EMG) activity was recorded from a major elbow extensor (anconeus). Results demonstrate that altering any sensory system impacts landing behavior, though loss of vision had the least effect. Blind animals showed significant differences in anconeus EMG timing relative to controls, but forelimb and hindlimb movements as well as the ability to successfully decelerate the body using the forelimbs were not affected. Compromising hindlimb proprioception led to distinctly different forelimb kinematics. Though EMG patterns were disrupted, animals in this condition were also able to decelerate after impact, though with less control, regularly allowing their trunks to make ground contact during landing. Animals with compromised vestibular systems showed the greatest deficits, both in takeoff and landing behavior, which were highly variable and rarely coordinated. Nevertheless, animals in this condition demonstrated EMG patterns and forelimb kinematics similar to those in control animals. The fact that no ablation entirely eliminates all aspects of landing preparation suggests that its underpinnings are complex and that there is no single sensory trigger for its initiation.

Topical proteolytic enzymes affect epidermal and dermal properties.

Although proteolytic enzymes have a history of use in skin care products it is not known whether they simply induce superficial exfoliation or with continued use can alter epidermal and dermal skin properties. We examined herein whether enhanced exfoliation resulting from treatment with an aspartyl dependent acid protease produces appearance improvements and over time, changes in the epidermis and dermis. Test participants applied 15% enzyme containing serum and a simple moisturizer twice daily for 3 months; a matched control group applied the same serum (without enzyme) and moisturizer. Changes in skin smoothness and texture, the depth and number of lines and wrinkles, and epidermal and dermal firmness and thickness were examined in a double-blind fashion. Treatment with 15% enzyme product(s) resulted in significant improvement in epidermal properties after 1 month and both epidermal and dermal properties after 3 months. The control group showed modest improvements in surface properties only. These results demonstrate that significant appearance benefits can be derived from use of exfoliative proteolytic enzymes. Such improvements are the result of changes to the epidermis and dermis and are strikingly similar to results observed with higher concentrations of AHAs (alpha hydroxy acids).

How muscles accommodate movement in different physical environments: aquatic vs. terrestrial locomotion in vertebrates.

Representatives of nearly all vertebrate classes are capable of coordinated movement through aquatic and terrestrial environments. Though there are good data from a variety of species on basic patterns of muscle recruitment during locomotion in a single environment, we know much less about how vertebrates use the same musculoskeletal structures to accommodate locomotion in physically distinct environments. To address this issue, we have gathered data from a broad range of vertebrates that move successfully through water and across land, including eels, toads, turtles and rats. Using high-speed video in combination with electromyography and sonomicrometry, we have quantified and compared the activity and strain of individual muscles and the movements they generate during aquatic vs. terrestrial locomotion. In each focal species, transitions in environment consistently elicit alterations in motor output by major locomotor muscles, including changes in the intensity and duration of muscle activity and shifts in the timing of activity with respect to muscle length change. In many cases, these alterations likely change the functional roles played by muscles between aquatic and terrestrial locomotion. Thus, a variety of forms of motor plasticity appear to underlie the ability of many species to move successfully through different physical environments and produce diverse behaviors in nature.

Hindlimb muscle function in relation to speed and gait: in vivo patterns of strain and activation in a hip and knee extensor of the rat (Rattus norvegicus).

Understanding how animals actually use their muscles during locomotion is an important goal in the fields of locomotor physiology and biomechanics. Active muscles in vivo can shorten, lengthen or remain isometric, and their mechanical performance depends on the relative magnitude and timing of these patterns of fascicle strain and activation. It has recently been suggested that terrestrial animals may conserve metabolic energy during locomotion by minimizing limb extensor muscle strain during stance, when the muscle is active, facilitating more economical force generation and elastic energy recovery from limb muscle-tendon units. However, whereas the ankle extensors of running turkeys and hopping wallabies have been shown to generate force with little length change (<6% strain), similar muscles in cats appear to change length more substantially while active. Because previous work has tended to focus on the mechanical behavior of ankle extensors during animal movements, the actions of more proximal limb muscles are less well understood. To explore further the hypothesis of force economy and isometric behavior of limb muscles during terrestrial locomotion, we measured patterns of electromyographic (EMG) activity and fascicle strain (using sonomicrometry) in two of the largest muscles of the rat hindlimb, the biceps femoris (a hip extensor) and vastus lateralis (a knee extensor) during walking, trotting and galloping. Our results show that the biceps and vastus exhibit largely overlapping bursts of electrical activity during the stance phase of each step cycle in all gaits. During walking and trotting, this activity typically commences shortly before the hindlimb touches the ground, but during galloping the onset of activity depends on whether the limb is trailing (first limb down) or leading (second limb down), particularly in the vastus. In the trailing limb, the timing of the onset of vastus activity is slightly earlier than that observed during walking and trotting, but in the leading limb, this activity begins much later, well after the foot makes ground contact (mean 7% of the step cycle). In both muscles, EMG activity typically ceases approximately two-thirds of the way through the stance phase. While electrically active during stance, biceps fascicles shorten, although the extent of shortening differs significantly among gaits (P<0.01). Total average fascicle shortening strain in the biceps is greater during walking (23+/-3%) and trotting (27+/-5%) than during galloping (12+/-5% and 19+/-6% in the trailing and leading limbs, respectively). In contrast, vastus fascicles typically lengthen (by 8-16%, depending on gait) over the first half of stance, when the muscle is electrically active, before shortening slightly or remaining nearly isometric over much of the second half of stance. Interestingly, in the leading limb during galloping, vastus fascicles lengthen prior to muscle activation and exhibit substantial shortening (10+/-2%) during the period when EMG activity is recorded. Thus, patterns of muscle activation and/or muscle strain differ among gaits, between muscles and even within the same muscle of contralateral hindlimbs (as during galloping). In contrast to the minimal strain predicted by the force economy hypothesis, our results suggest that proximal limb muscles in rats operate over substantial length ranges during stance over various speeds and gaits and exhibit complex and changing activation and strain regimes, exemplifying the variable mechanical roles that muscles can play, even during level, steady-speed locomotion.

Hindlimb extensor muscle function during jumping and swimming in the toad (Bufo marinus).

Many anurans use their hindlimbs to generate propulsive forces during both jumping and swimming. To investigate the musculoskeletal dynamics and motor output underlying locomotion in such physically different environments, we examined patterns of muscle strain and activity using sonomicrometry and electromyography, respectively, during jumping and swimming in the toad Bufo marinus. We measured strain and electromyographic (EMG) activity in four hindlimb muscles: the semimembranosus, a hip extensor; the plantaris, an ankle extensor; and the gluteus and cruralis, two knee extensors. During jumping, these four muscles are activated approximately simultaneously; however, joint extension appears to be temporally staggered, with the hip beginning to extend prior to or initially faster than the more distal knee and ankle joints. Mirroring this pattern, the gluteus and plantaris shorten quite slowly and over a small distance during the first half of limb extension during take-off, before beginning to shorten rapidly. The hip and knee extensors finish shortening near the point of take-off (when the feet leave the ground), while the ankle-extending plantaris, which exhibits the longest-duration EMG burst, on average, always completes its shortening after take-off (mean 26 ms). During swimming, activation of the four muscles is also nearly synchronous at the start of a propulsive stroke. The onset of fascicle shortening is temporally staggered, with the knee extensors beginning to shorten first, prior to the hip and ankle extensors. In addition, the knee extensors also often exhibit some degree of slow passive shortening prior to the onset of EMG activity. The offset of muscle shortening during swimming is also staggered, and to a much greater extent than during jumping. During swimming, the cruralis and gluteus finish shortening first, the semimembranosus finishes 30-60 ms later, and the plantaris, which again exhibits the longest EMG burst, finishes shortening last (mean 150 ms after the cruralis). Interestingly, much of this extended shortening in the plantaris occurs at a relatively slow velocity and may reflect passive ankle extension caused by fluid forces, associated with previously generated unsteady (accelerative) limb movements, acting on the foot. Average EMG burst intensity tends to be greater during jumping than during swimming in all muscles but the gluteus. However, EMG burst duration only changes between jumping and swimming in the cruralis (duration during jumping is nearly twice as long as during swimming). The cruralis is also the only muscle to exhibit substantially greater fractional shortening during jumping (mean 0.28) than during swimming (mean 0.20 active strain, 0.22 total strain). On the basis of these results, it appears that toad hindlimb function is altered between jumping and swimming. Moreover, these functional differences are influenced by passive effects associated with physical differences between the external environments, but are also actively mediated by shifts in the motor output and mechanical behavior of several muscles.

Patterns of white muscle activity during terrestrial locomotion in the American eel (Anguilla rostrata).

Eels (Anguilla rostrata) are known to make occasional transitory excursions into the terrestrial environment. While on land, their locomotor kinematics deviate drastically from that observed during swimming. In this study, electromyographic (EMG) recordings were made from white muscle at various longitudinal positions in eels performing undulatory locomotion on land to determine the muscle activity patterns underlying these terrestrial movements. As during swimming, eels propagate a wave of muscle activity from anterior to posterior during terrestrial locomotion. However, the intensity of EMG bursts is much greater on land (on average approximately five times greater than in water). In addition, anteriorly located musculature has higher-intensity EMG bursts than posteriorly located muscle during locomotion on land. EMG duty cycle (burst duration relative to undulatory cycle time) is significantly affected by longitudinal position during terrestrial locomotion, and duty cycles are significantly greater on land (0.4-0.5 cycles) than in water (0. 2-0.3 cycles). Finally, as in swimming, a phase shift in the timing of muscle activity exists such that posteriorly located muscle fibers become activated earlier in their strain cycle than do more anteriorly located fibers. However, fibers become activated much later in their muscle strain cycle on land than in water. Therefore, it is clear that, while eels propagate a wave of muscle activity posteriorly to generate backward-traveling waves that generate propulsive thrust both in water and on land, the specific patterns of timing and the intensity of muscle activity are substantially altered depending upon the environment. This suggests that physical differences in an animal's external environment can play a substantial role in affecting the motor control of locomotion, even when similar structures are used to generate the propulsive forces.

Dynamics of muscle function during locomotion: accommodating variable conditions.

Much of what we know about animal locomotion is derived from studies examining animals moving within a single, homogeneous environment, at a steady speed and along a flat grade. As a result, the issue of how musculoskeletal function might shift to accommodate variability within the external environment has remained relatively unexplored. One possibility is that locomotor muscles are differentially recruited depending upon the environment in which the animal is moving. A second possibility is that the same muscles are recruited, but that they are activated in a different manner so that their contractile function differs according to environment. Finally, it is also possible that, in some cases, animals may not need to alter their musculoskeletal function to move under different external conditions. In this case, however, the mechanical behavior appropriate for one environmental condition may constrain locomotor performance in another. To begin to explore the means by which animals accommodate variable conditions in their environment, we present three case studies examining how musculoskeletal systems function to allow locomotion under variable conditions: (1) eels undulating through water and across land, (2) turkeys running on level and inclined surfaces, and (3) ducks using their limbs to walk and to paddle. In all three of these examples, the mechanical behavior of some muscle(s) involved in locomotion are altered, although to different degrees and in different ways. In the running turkeys, the mechanical function of a major ankle extensor muscle shifts from contracting isometrically on a flat surface (producing little work and power), to shortening actively during contraction on an uphill gradient (increasing the amount of work and power generated). In the ducks, the major ankle extensor undergoes the same general pattern of activation and shortening in water and on land, except that the absolute levels of muscle stress and strain and work output are greater during terrestrial locomotion. In eels, a transition to land elicits changes in electromyographic duty cycles and the relative timing of muscle activation, suggesting some alteration in the functional mechanics of the underlying musculature. Only by studying muscle function in animals moving under more variable conditions can we begin to characterize the functional breadth of the vertebrate musculoskeletal system and understand more fully its evolutionary design.

Anguilliform locomotion in an elongate salamander (Siren intermedia): effects of speed on axial undulatory movements

Many workers interested in the mechanics and kinematics of undulatory aquatic locomotion have examined swimming in fishes that use a carangiform or subcarangiform mode. Few empirical data exist describing and quantifying the movements of elongate animals using an anguilliform mode of swimming. Using high-speed video, I examine the axial undulatory kinematics of an elongate salamander, Siren intermedia, in order to provide data on how patterns of movement during swimming vary with body position and swimming speed. In addition, swimming kinematics are compared with those of other elongate vertebrates to assess the similarity of undulatory movements within the anguilliform locomotor mode. In Siren, most kinematic patterns vary with longitudinal position. Tailbeat period and frequency, stride length, Froude efficiency and the lateral velocity and angle of attack of tail segments all vary significantly with swimming speed. Although swimming speed does not show a statistically significant effect on kinematic variables such as maximum undulatory amplitude (which increases non-linearly along the body), intervertebral flexion and path angle, examination of the data suggests that speed probably has subtle and site-specific effects on these variables which are not detected here owing to the small sample size. Maximum lateral displacement and flexion do not coincide in time within a given tailbeat cycle. Furthermore, the maximum orientation (angle with respect to the animal's direction of forward movement) and lateral velocity of tail segments also do not coincide in time. Comparison of undulatory movements among diverse anguilliform swimmers suggests substantial variation across taxa in parameters such as tailbeat amplitude and in the relationship between tailbeat frequency and swimming speed. This variation is probably due, in part, to external morphological differences in the shape of the trunk and tail among these taxa.

Efficacy of naproxen sodium for exercise-induced dysfunction muscle injury and soreness.

OBJECTIVE: To examine the efficacy of naproxen sodium for exercise-induced dysfunction, muscle injury, and soreness. DESIGN: Double-blind crossover. SETTING: Community. PARTICIPANTS: Eight young adult, healthy males. INTERVENTIONS: Ten sets of seven to 10 eccentric actions with each quadriceps femoris with a load equal to 85% of the eccentric one repetition maximum (1RM) followed by 10 days of naproxen sodium or placebo. MAIN OUTCOME MEASURES: Concentric 1RM; cross-sectional area (CSA) and spin-spin relaxation time (T2) of quadriceps femoris, and subjective rating of thigh soreness pre- and 1, 4, and 10 days postexercise; subjective rating of ability to sleep or perform morning activities daily during recovery. RESULTS: Concentric 1RM was reduced by (p = 0.0001) 41% day 1 of recovery; by day 4 of recovery, it had increased (p = 0.0145) to 24% below baseline in the drug trial, but did not change for the placebo trial. By day 10 of recovery, concentric 1RM was 16 and 26% below (p = 0.0001) baseline for the drug and placebo trials, respectively. Quadriceps femoris CSA and T2 were increased (p < or = 0.0250) after exercise, with the greatest (p = 0.0008) responses evident on day 4 of recovery. At this time, each variable showed greater increases (p < or = 0.0129) for the placebo than for the drug trial 8 vs. 5 and 26 vs. 15%, respectively). The CSA of the quadriceps femoris showing an elevated T2 was 27 and 37% greater (p < or = 0.0085) for the placebo than for the drug trial on days 1 and 4 of recovery, respectively. The percentage of quadriceps femoris CSA with an elevated T2 (40%) was 1/3 greater (p < or = 0.0138) for the placebo than for the drug trial on these days. Thigh soreness was lower (day 4, p = 0.0087) and the ability to sleep or perform morning activities was less (p < or = 0.0030) compromised (days 3 and 4) during recovery in the drug trial. CONCLUSIONS: The results suggest that naproxen sodium improved recovery after eccentrically biased exercise, probably by attenuating expression of the inflammatory response to muscle injury.

Kinematics of feeding in bluegill sunfish: is there a general distinction between aquatic capture and transport behaviors?

Despite numerous studies of food transport in terrestrial vertebrates, little is known about this aspect of the feeding repertoire in aquatic vertebrates. Previous work had predicted that the kinematics of aquatic prey capture by suction feeding should be similar to those of prey transport. However, recent analyses of aquatic prey capture and transport in the tiger salamander Ambystoma tigrinum have contradicted this hypothesis, and document numerous differences between these two behaviors. In this study, using high-speed video and statistical analyses, we compare prey capture and transport kinematics in a ray-finned fish (Lepomis macrochirus, the bluegill sunfish) to examine the generality of differences between capture and transport behaviors in aquatic vertebrates. Compared with prey capture, prey transport is significantly more rapid and tends to have reduced lower jaw excursions, while having similar hyoid movements. A nested analysis of variance was used to analyze six variables common to both this analysis of Lepomis macrochirus and a previous study of Ambystoma tigrinum; none of these six variables showed significant variation between taxa. These results indicate that aquatic prey transport is kinematically distinct from capture behavior and that the distinctions between these two behaviors are remarkably consistent in two phylogenetically divergent lower vertebrate taxa. Such consistent kinematic differences have not been found in amniote taxa studied to date, but may constitute a plesiomorphic feature of vertebrate feeding systems.

Interdisciplinary team training in geriatrics: reaching out to small and medium-size communities.

Since 1989, six teams in the state of Michigan have been involved in a team training program designed to promote the development of geriatric services in small to medium-size communities. The program was enthusiastically received by participants, but after 18 months, only half of the teams had implemented clinical services for older adults. Monitoring the progress of the teams over 18 months and analyzing the activities of two teams revealed that financially stable and supportive sponsoring agencies and the community were critical factors in the implementation of interdisciplinary clinical services in geriatrics. Future team training programs trying to promote the development of geriatric services in small to medium-size communities should try to address these issues through community organization interventions.

Relation between socioeconomic deprivation and pathological prognostic factors in women with breast cancer.

OBJECTIVE: To investigate the relation between socioeconomic deprivation and pathological prognostic factors in women with breast cancer as a possible explanation for socioeconomic differences in survival. DESIGN: Retrospective analysis of data from cancer registry and from pathology and biochemistry records. SETTING: Catchment areas of two large teaching hospitals in Glasgow. SUBJECTS: 1361 women aged under 75 who had breast cancer diagnosed between 1980 and 1987. MAIN OUTCOME MEASURES: Tumour size, axillary lymph node status, histological grade, and oestrogen receptor concentration in relation to deprivation category of area of residence. RESULTS: There was no significant relation between socioeconomic deprivation and four pathological prognostic factors: 93 (32%) women in the most affluent group presented with tumours less than 20 mm in size compared with 91 (31%) women in the most deprived group; 152 (48%) of the most affluent group presented with negative nodes compared with 129 (46%) of the most deprived group; 23 (22%) of the most affluent group presented with grade I tumours compared with 12 (17%) of the most deprived group; and 142 (51%) of the most affluent group had a low oestrogen receptor concentration at presentation compared with 148 (52%) of the most deprived group. None of these differences was statistically significant. CONCLUSIONS: Differences in survival from breast cancer by socioeconomic deprivation category could not be accounted for by differences in tumour stage or biology. Other possible explanations, such as differences in treatment or in host response, should be investigated.

AQUATIC PREY TRANSPORT AND THE COMPARATIVE KINEMATICS OF AMBYSTOMA TIGRINUM FEEDING BEHAVIORS

Four definable feeding behaviors used during the metamorphic life history of tiger salamanders are terrestrial prey capture and transport (as adults) and aquatic prey capture and transport (as larvae). Previous studies have focused primarily on the first three of these behaviors and thus aquatic prey transport is poorly understood. These studies have indicated that terrestrial prey capture has unique kinematic and motor patterns, whereas the other behaviors are quite similar to one another. Using high-speed video analysis, the kinematics of aquatic prey transport in larval Ambystoma tigrinum are described using both lateral and ventral views. These kinematic patterns are statistically compared with the kinematic patterns of aquatic prey capture, terrestrial prey capture and terrestrial prey transport. Statistical analyses allow us to assess the similarities and differences among the four behaviors and to determine the effect of the metamorphic environmental transition (water to land) and morphological changes of the feeding mechanism (suction- to lingual-based) on feeding kinematics. Our data do not support the notion that lingual-based terrestrial prey capture uses unique kinematic patterns compared with the other three behaviors, which consist of similar movements. Rather, each of the feeding behaviors has unique kinematic features that distinguish it from the others. In addition, variation in tiger salamander feeding kinematics is more a function of the feeding event (whether it is capture or transport) than of the environment in which the feeding takes place or the morphology of the feeding mechanism. Finally, we encourage the use of parsimony-based methods of phylogenetic analysis to analyze shared traits (such as kinematic and/or electromyographic variables) in comparative studies of behavior within a single species.

Disruptive behavior in elderly nursing home residents: a survey of nursing staff.

A significant number of nursing home residents exhibit behavior disturbances that are disruptive to the living and working environment in the nursing home. The most common disruptive behaviors cited by licensed nursing personnel included hitting/slapping, verbally aggressive remarks, screaming, pacing, wandering, and repetitive verbal requests. Self-injurious behavior, property destruction, and hiding things were not mentioned. Many of the nursing strategies listed by nursing staff as being used to alleviate disruptive behaviors are traditional care activities, eg, talking to and counseling patients, touching, or altering care. However, chemical and physical restraints were also frequently listed.

Pelvic muscle exercise for stress urinary incontinence in elderly women.

PURPOSE: To compare pelvic muscle exercise to pharmacologic treatment of stress urinary incontinence, the most common cause of urine leakage reported by community-living elderly women. SUBJECTS: Convenience sample of 157 community-living women, aged 55 to 90 years, after completion of a comprehensive diagnostic evaluation. METHODS: Eighty-two subjects were randomly assigned to the exercise protocol (with a 34% attrition rate). Pelvic muscle exercises were taught and monitored for 6 months. Phenylpropanolamine hydrochloride was given to the other group in a dose of 50 mg a day, increasing to 50 mg twice a day. MAIN RESULTS: Treatment outcomes (subjective improvement, self recorded frequency of wetting) were equally satisfactory in both groups. The response to exercises was as good in 5 months as in 6. It was also as good when the minimum recommended number of exercises per day was 80 as when it was 125. CONCLUSIONS: Among those completing the protocol, pelvic exercises were beneficial in reducing stress incontinence, and the benefit was comparable to that produced by phenylpropanolamine.

A digital test for pelvic muscle strength in older women with urinary incontinence.

A digital test of pelvic muscle strength for evaluation of a pelvic muscle exercise (PME) program was developed with a sample of 338 incontinent women living at home. Factors of perceived pressure, alteration of the vertical plane, and time were combined to form a 7-point scale ranging from 0 to 4. Test-retest for the anteroposterior score was r = .65, p less than .01 with interrater reliability, r = .91, p less than .01. Relationship to other variables and further development of the measure are discussed.

Relationship between drug use and urinary incontinence in elderly women.

Two hundred older women with urinary incontinence were studied to observe the influence of their prescription and nonprescription drug use on symptoms of incontinence. Ninety percent of women reported using medication, with an average use of four drugs. Medications statistically associated with urinary incontinence symptomatology were prostaglandin inhibitors, diuretics, and estrogen therapy. Further studies are needed to clarify the relationship between medication usage and the presence and severity of urinary incontinence.