Effect of high level of bladder filling on spinal nociception and motoneuronal excitability

To verify whether high level of bladder distension may counteract the inhibitory effect of descending pathways on sacral spinal cord neurons and to investigate which spinal circuitries are possibly involved in such a viscero-somatic interaction. Nociceptive withdrawal reflex (NWR), cutaneous silent period (CSP), and H-reflex were recorded in both lower and upper limbs of twenty-eight healthy subjects. Subjects were examined during baseline (empty bladder, no voiding desire), high level of bladder filling (urgency desire), and control (empty bladder, no voiding desire) sessions. Results showed that the NWR and its related pain perception were reduced in the upper limbs, while only a pain perception reduction in males was observed in the lower limbs. The H-reflex was inhibited in both limbs. No effects were found on the CSP duration. The decrease in both the NWR and its related pain perception in the upper limbs confirms the presence of a bladder distension-induced descending inhibitory modulation on nociception at spinal level. The lack of a similar inhibitory effect in the lower limbs suggests that excitatory nociceptive inputs from bladder afferents counterbalance the inhibitory effect on sacral spinal cord. The lack of the descending inhibitory effect may be a mechanism aimed at forcing the micturition phase to avoid bladder damage caused by bladder sovradistension

Introduction to Prosthetic Limbs

Approximately 2 million people in the Unites States alone have had an amputation, and many of these people use a prosthetic limb daily. The prosthetic limb, which began as a primitive device, is now a highly sophisticated piece of technology. It is because of many devoted scientists that we now have access to this life-transforming device. There are many causes for amputation; a few causes included disease, accidents, and congenital conditions. Although missing a limb can be life-altering, health care teams consisting of physicians, physical therapists, and orthotists are dedicated to helping people return to everyday activities and to excel in their pursuits

Active joints for microrobot limbs

The authors propose an electrostatic actuator for active joints. The active joint consists of two plates, one of which is a bilayer and bent by the bimorph effect. The plates are clamped to each other at one edge. A voltage between the plates leads to a very large field at the clamp where the plates are in intimate contact, thereby producing a force large enough to pull the bent bimorph cantilever beam to the other plate. The design uses an actuator in which large electrical forces acting over a short distance are used to produce large deflections. An appealing application of this actuation principle is seen in active joints for robot arms, e.g. by attaching members to the actuator and by combining two or more active joints and members to form micro robot arms, legs and grippers

Anatomical network analysis of the musculoskeletal system reveals integration loss and parcellation boost during the fins-to-limbs transition

Tetrapods evolved from within the lobe-finned fishes around 370 Ma. The evolution of limbs from lobe-fins entailed a major re-organization of the skeletal and muscular anatomy of appendages in early tetrapods. Concurrently, a degree of similarity between pectoral and pelvic appendages also evolved. Here, we compared the anatomy of appendages in extant lobe-finned fishes (Latimeria and Neoceratodus) and anatomically plesiomorphic amphibians (Ambystoma, Salamandra) and amniotes (Sphenodon) to trace and reconstruct the musculoskeletal changes that took place during the fins-to-limbs transition. We quantified the anatomy of appendages using network analysis. First, we built network models—in which nodes represent bones and muscles, and links represent their anatomical connections—and then we measured network parameters related to their anatomical integration, heterogeneity, and modularity. Our results reveal an evolutionary transition toward less integrated, more modular appendages. We interpret this transition as a diversification of muscle functions in tetrapods compared to lobe-finned fishes. Limbs and lobe-fins show also a greater similarity between their pectoral and pelvic appendages than ray-fins do. These findings on extant species provide a basis for future quantitative and comprehensive reconstructions of the anatomy of limbs in early tetrapod fossils, and a way to better understand the fins-to-limbs transition

Tactile sensing means for prosthetic limbs

An improved prosthetic device characterized by a frame and a socket for mounting on the stump of a truncated human appendage is described. Flexible digits extend from the distal end and transducers located within the digits act as sensing devices for detecting tactile stimuli. The transducers are connected through a power circuit with a slave unit supported by a strap and fixed to the stump. The tactile stimuli detected at the sensing devices are reproduced and applied to the skin of the appendage in order to stimulate the sensory organs located therein

Polydactylous limbs in Strong's Luxoid mice result from ectopic polarizing activity

Strong's Luxoid (1st^D) is a semidominant mouse mutation in which heterozygotes show preaxial hindlimb polydactyly, and homozygotes show fore- and hindlimb polydactyly. The digit patterns of these polydactylous limbs resemble those caused by polarizing grafts, since additional digits with posterior character are present at the anterior side of the limb. Such observations suggest that 1st^D limb buds might contain a genetically determined ectopic region of polarizing activity. Accordingly, we show that mutant embryos ectopically express the pattern-determining genes fibroblast growth factor 4 (fgf-4), sonic hedgehog (shh), and Hoxd-12 in the anterior region of the limb. Further, we show that anterior mesoderm from mutant limbs exhibits polarizing activity when grafted into host chicken limbs. In contrast to an experimentally derived polydactylous transgenic mouse, forelimbs of homozygotes show a normal pattern of Hoxb-8 expression, indicating that the duplication of polarizing tissue here occurs downstream or independently of Hoxb-8. We suggest that the 1st gene product is involved in anteroposterior axis formation during normal limb development

A case study of technology transfer: Rehabilitative engineering at Rancho Los Amigos Hospital

The transfer of NASA technolgy to rehabilitative applications of artificial limbs is studied. Human factors engineering activities range from orthotic manipulators to tiny dc motors and transducers to detect and transmit voluntary control signals. It is found that bicarbon implant devices are suitable for medical equipment and artificial limbs because of their biological compatibility with human body fluids and tissues

Development of human limbs.

This work offers a new view on the developmental history of tetrapods. It proposes an original evolution model of human limbs based on metameric formation of osteogenic buds in accordance to primary segmentation and biplanar symmetry. While going through evolution, osteogenic buds initially identical to each other were changing their sizes, realigning, regressing, uniting while keeping the direction of the formation in accordance to the following formula (taking into account sesamoid bones):
2; 1; 2; 3; 2; 3; 5; 5; 8; 8 (in the upper limb together with the upper limb girdle); 3; 2; 3; 2; 1; 2; 8; 8; 5; 5 (in the lower limb together with the pelvic bones)

Concurrent adaptation to opposing visual displacements during an alternating movement.

It has been suggested that, during tasks in which subjects are exposed to a visual rotation of cursor feedback, alternating bimanual adaptation to opposing rotations is as rapid as unimanual adaptation to a single rotation (Bock et al. in Exp Brain Res 162:513–519, 2005). However, that experiment did not test strict alternation of the limbs but short alternate blocks of trials. We have therefore tested adaptation under alternate left/right hand movement with opposing rotations. It was clear that the left and right hand, within the alternating conditions, learnt to adapt to the opposing displacements at a similar rate suggesting that two adaptive states were formed concurrently. We suggest that the separate limbs are used as contextual cues to switch between the relevant adaptive states. However, we found that during online correction the alternating conditions had a significantly slower rate of adaptation in comparison to the unimanual conditions. Control conditions indicate that the results are not directly due the alternation between limbs or to the constant switching of vision between the two eyes. The negative interference may originate from the requirement to dissociate the visual information of these two alternating displacements to allow online control of the two arms