The evolution of two distinct strategies of moth flight

Across insects, wing shape and size have undergone dramatic divergence even in closely related sister groups. However, we do not know how morphology changes in tandem with kinematics to support body weight within available power and how the specific force production patterns are linked to differences in behaviour. Hawkmoths and wild silkmoths are diverse sister families with divergent wing morphology. Using three-dimensional kinematics and quasi-steady aerodynamic modelling, we compare the aerodynamics and the contributions of wing shape, size and kinematics in 10 moth species. We find that wing movement also diverges between the clades and underlies two distinct strategies for flight. Hawkmoths use wing kinematics, especially high frequencies, to enhance force and wing morphologies that reduce power. Silkmoths use wing morphology to enhance force, and slow, high-amplitude wingstrokes to reduce power. Both strategies converge on similar aerodynamic power and can support similar body weight ranges. However, inter-clade within-wingstroke force profiles are quite different and linked to the hovering flight of hawkmoths and the bobbing flight of silkmoths. These two moth groups fly more like other, distantly related insects than they do each other, demonstrating the diversity of flapping flight evolution and a rich bioinspired design space for robotic flappers.

Clinical Application Prospect of Human Synovial Tissue Stem Cells from Osteoarthritis Grade IV Patients in Cartilage Regeneration

Osteoarthritis (OA) is a joint problem that continues to increase in prevalence as life expectancy increases. OA can affect any joint, especially those that support body weight such as the knee and hip joint. Although both primary and secondary OA have the same clinical symptoms, it can be caused by different etiologies. OA is no longer considered a degenerative disease, although age is still a major factor. Various attempts have been made to regenerate joint cartilage damaged by OA. The use of stem cells in OA therapy is a very promising opportunity. Stem cells are undifferentiated biological cells and are multipotent to differentiate into specific cells. In principle, local stem cells are the best source of stem cells to regenerate the surrounding tissue. The synovial membrane is a tissue in the joint that can regenerate. After synovectomy surgery, repair, and growth of synovial tissue occur rapidly. Synovial tissue as a source of stem cells only provides a limited amount. One source of synovial tissue that can be used is tissue taken from the total knee replacement process in grade 4 OA patients. However, it is necessary to prove the potential of synovial tissue stem cells originating from old-age donors.

Mechanical evidence that flamingos can support their body on one leg with little active muscular force

Flamingos (Phoenicopteridae) often stand and sleep on one leg for long periods, but it is unknown how much active muscle contractile force they use for the mechanical demands of standing on one leg: body weight support and maintaining balance. First, we demonstrated that flamingo cadavers could passively support body weight on one leg without any muscle activity while adopting a stable, unchanging, joint posture resembling that seen in live flamingos. By contrast, the cadaveric flamingo could not be stably held in a two-legged pose, suggesting a greater necessity for active muscle force to stabilize two-legged versus one-legged postures. Our results suggest that flamingos engage a passively engaged gravitational stay apparatus (proximally located) for weight support during one-legged standing. Second, we discovered that live flamingos standing on one leg have markedly reduced body sway during quiescent versus alert behaviours, with the point of force application directly under the distal joint, reducing the need for muscular joint torque. Taken together, our results highlight the possibility that flamingos stand for long durations on one leg without exacting high muscular forces and, thus, with little energetic expenditure.

Safety and Feasibility of a Novel Gait Training Device Using a “Spacesuit” to Support Body Weight

In the U.S. alone, 7.5 million individuals have survived stroke, traumatic brain injury, and spinal cord injury, and over a million new patients are diagnosed every year [1]. Most of these patients will need gait rehabilitation. Body weight supported gait training is a widely used rehabilitation therapy to improve gait function [2]. Commonly, a physical therapist provides assistance using a gait belt to support the patient. Sometimes two or three therapists may be needed for severely impaired patients. Bodyweight supported treadmill training uses a harness attached to an overhead lift to support body weight [2], however harness systems often cause discomfort and may take significant time to set up and take down. Lite Run Corporation has developed a system for the treatment of patients with gait and balance difficulties that uses differential air pressure inside a specially designed suit to reduce up to 50 percent of a patient’s body weight. The suit facilitates patient ambulation using technology like that in astronaut spacesuits to achieve comfort and flexibility. Potential benefits include longer therapy sessions due to greater comfort and greater unweighting, as well as the therapeutic benefits of being upright and walking for subjects unable to stand independently. The suit is used in conjunction with the Gait Trainer device shown in Figure 1 which provides air pressure to the suit and support for the patient. Gait Trainer features include: 1) electro-mechanical and pneumatic controls to support the suit and patient when rising from sitting to standing and ambulating during therapy — so that a single therapist can safely transfer a patient from a wheelchair and practice gait therapy; 2) an open design that permits access to patient’s body and legs by the therapist; 3) a compact profile that provides easy maneuverability; 4) a “base spread” function that permits positioning close to a patient when seated in wheel chair, bed or therapy table. Together these features provide safety and stability for the patient and reduced physical burden on the therapist. The objectives for the current study were to establish the safety and feasibility of the Gait Trainer, validate user design requirements, and to test the hypothesis that the rate of perceived exertion when using the device is significantly less than during unaided walking therapy.

Effects of Velocity and Weight Support on Ground Reaction Forces and Metabolic Power during Running

The biomechanical and metabolic demands of human running are distinctly affected by velocity and body weight. As runners increase velocity, ground reaction forces (GRF) increase, which may increase the risk of an overuse injury, and more metabolic power is required to produce greater rates of muscular force generation. Running with weight support attenuates GRFs, but demands less metabolic power than normal weight running. We used a recently developed device (G-trainer) that uses positive air pressure around the lower body to support body weight during treadmill running. Our scientific goal was to quantify the separate and combined effects of running velocity and weight support on GRFs and metabolic power. After obtaining this basic data set, we identified velocity and weight support combinations that resulted in different peak GRFs, yet demanded the same metabolic power. Ideal combinations of velocity and weight could potentially reduce biomechanical risks by attenuating peak GRFs while maintaining aerobic and neuromuscular benefits. Indeed, we found many combinations that decreased peak vertical GRFs yet demanded the same metabolic power as running slower at normal weight. This approach of manipulating velocity and weight during running may prove effective as a training and/or rehabilitation strategy.

Independent metabolic costs of supporting body weight and accelerating body mass during walking

The metabolic cost of walking is determined by many mechanical tasks, but the individual contribution of each task remains unclear. We hypothesized that the force generated to support body weight and the work performed to redirect and accelerate body mass each individually incur a significant metabolic cost during normal walking. To test our hypothesis, we measured changes in metabolic rate in response to combinations of simulated reduced gravity and added loading. We found that reducing body weight by simulating reduced gravity modestly decreased net metabolic rate. By calculating the metabolic cost per Newton of reduced body weight, we deduced that generating force to support body weight comprises ∼28% of the metabolic cost of normal walking. Similar to previous loading studies, we found that adding both weight and mass increased net metabolic rate in more than direct proportion to load. However, when we added mass alone by using a combination of simulated reduced gravity and added load, net metabolic rate increased about one-half as much as when we added both weight and mass. By calculating the cost per kilogram of added mass, we deduced that the work performed on the center of mass comprises ∼45% of the metabolic cost of normal walking. Our findings support the hypothesis that force and work each incur a significant metabolic cost. Specifically, the cost of performing work to redirect and accelerate the center of mass is almost twice as great as the cost of generating force to support body weight.

Metabolic cost of generating horizontal forces during human running

Previous studies have suggested that generating vertical force on the ground to support body weight (BWt) is the major determinant of the metabolic cost of running. Because horizontal forces exerted on the ground are often an order of magnitude smaller than vertical forces, some have reasoned that they have negligible cost. Using applied horizontal forces (AHF; negative is impeding, positive is aiding) equal to −6, −3, 0, +3, +6, +9, +12, and +15% of BWt, we estimated the cost of generating horizontal forces while subjects were running at 3.3 m/s. We measured rates of oxygen consumption (V˙o 2) for eight subjects. We then used a force-measuring treadmill to measure ground reaction forces from another eight subjects. With an AHF of −6% BWt,V˙o 2 increased 30% compared with normal running, presumably because of the extra work involved. With an AHF of +15% BWt, the subjects exerted ∼70% less propulsive impulse and exhibited a 33% reduction inV˙o 2. Our data suggest that generating horizontal propulsive forces constitutes more than one-third of the total metabolic cost of normal running.

The Subacute Neurotoxicity of Excess Pyridoxine HCl and Clioquinol (5-Chloro-7-Iodo-8-Hydroxyquinoline) in Beagle Dogs. I. Clinical Disease

The clinical and clinicopathologic effects of excess oral pyridoxine hydrochloride (150 mg/kg body weight/day) and clioquinol (200 mg/kg body weight/day) alone and in combination were evaluated in adult Beagle dogs over an experimental period of approximately 100 days. Anorexia and loss of body weight occurred in the first weeks of the trial period in each treatment group, but was most severe in dogs given both compounds. Dogs in each treatment group (10 of 10 pyridoxine-treated dogs, 6 of 13 clioquinol-treated dogs and 12 of 13 pyridoxine plus clioquinol-treated dogs) developed neurologic disease, manifested principally by ataxia. Pyridoxine-treated dogs had proprioceptive loss involving both fore- and hindquarters, characterized by stiff, spastic, dysmetric leg movements. In clioquinol-treated dogs, dysmetric leg movements were accompanied by failure to support body weight in the hindquarters, but similar forelimb involvement occurred in severely affected dogs. The neurologic disease in dogs given both compounds varied; signs in some dogs resembled those of affected dogs of the pyridoxine-treated group, and in others, those in the clioquinol-treated group. Erythrocyte counts, hemoglobin concentrations and packed cell volumes were reduced in dogs in each treatment group and were lowest in dogs given both compounds. Plasma protein was mildly reduced in dogs given pyridoxine or pyridoxine plus clioquinol. Few or no differences were present in the leukocyte counts, blood urea nitrogen concentrations, in activities of serum alanine aminotransferase and aspartate aminotransferase, and in concentrations of sodium, chloride or potassium in treated dogs as compared to control dogs.