Successful replantation of lower leg and foot, with good sensibility and function.

The successful replantation of the lower part of a leg with the foot is reported in a 17-year-old boy. Adequate protective sensibility was obtained, and he walks well with a 3-inch lift on that shoe. He is also able to hike, climb, swim, dive, and engage in most normal activities. The pros and cons of leg replantation are considered.     

A pedal corer for the quantitative sampling of sediments and benthic organisms in submerged areas accessible on foot

This paper presents a new device to collect quantitative samples of sediment and benthic organisms. The device is specially designed for sampling with the advantages of box-corer or Eckman dredges in submerged areas that are accessible on foot. The pedal corer is a simple, lightweight, user-friendly device that does not disturb the sediment structure and provides easy access to the sample contained inside the core. With this device, sampling in shallow water zones that are constantly submerged is made easy and sampling time is extended in intertidal zones. Handling editor: J. Saros     

The effect of submergence on heart rate and oxygen consumption of swimming seals and sea lions

Respiratory, metabolic, and cardiovascular responses to swimming were examined in two species of pinniped, the harbor seal (Phoca vitulina) and the California sea lion (Zalophus californianus). 1. Harbor seals remained submerged for 82-92% of the time at swimming speeds below 1.2 m.s-1. At higher speeds, including simulated speeds above 1.4 m.s-1, the percentage of time spent submerged decreased, and was inversely related to body weight. In contrast, the percentage of time spent submerged did not change with speed for sea lions swimming from 0.5 m.s-1 to 4.0 m.s-1. 2. During swimming, harbor seals showed a distinct breathhold bradycardia and ventilatory tachycardia that were independent of swimming speed. Average heart rate was 137 beats.min-1 when swimming on the water surface and 50 beats.min-1 when submerged. A bimodal pattern of heart rate also occurred in sea lions, but was not as pronounced as in the seals. 3. The weighted average heart rate (WAHR), calculated from measured heart rate and the percentage time spent on the water surface or submerged, increased linearly with swimming speed for both species. The graded increase in heart rate with exercise load is similar to the response observed for terrestrial mammals. 4. The rate of oxygen consumption increased exponentially with swimming speed in both seals and sea lions. The minimum cost of transport calculated from these rates ranged from 2.3 to 3.6 J.m-1.kg-1, and was 2.5-4.0 times the level predicted for similarly-sized salmonids. Despite different modes of propulsion and physiological responses to swimming, these pinnipeds demonstrate similar transport costs.     

Isolation of a substance activating foot formation in hydra

We have developed an assay for a substance from hydra that accelerates foot regeneration in the animal. This substance is specific for the foot as evidenced by the following findings: (1) It is present in the animal as a steep gradient descending from foot to head, paralleling the foot-forming potential of the tissue (2) It does not accelerate head regeneration, nor do the head factors of hydra discovered by Schaller (1973) and Berking (1977) accelerate foot regeneration. We propose that the foot-activating substance is a morphogen responsible for foot formation in hydra. The foot activator can be extracted from hydra tissue with methanol and separated from other known morphogens of hydra by gel filtration and ion-exchange chromatography. A substance with similar biological and physicochemical properties can be isolated from sea anemones.     

Ultraviolet irradiation initiates ectopic foot formation in regenerating hydra and promotes budding

We have studied the effects of ultraviolet-C (UVC) and Ultraviolet-B (UVB) on growth and pattern formation inPelmatohydra oligactis. UVC brings about a significant increase in budding in intact hydra while UVB does not exhibit such an effect. Excessive budding could be a response for survival at wavelengths that damage biological tissues. If the head or base piece of a bisected hydra is irradiated and recombined with the unirradiated missing part, regeneration proceeds normally indicating that exposure of a body part with either an intact head or foot to UVC does not influence pattern formation. Most significantly, in the middle piece, but not in the head or the base piece of a trisected hydra, UVC leads to initiation of ectopic feet formation in almost one third of the cases. Thus, UV irradiation interferes with pattern formation in regenerating hydra, possibly by changing positional values, and promotes budding in intact hydra. This is the first report on induction of ectopic feet formation by UV in regenerating hydra and opens up the possibility of using UV irradiation as a tool to understand pattern formation in the enigmatic hydra     

Analysis of head and foot formation inHydra by means of an endogenous inhibitor

Summary In tissue regenerating the head, the ability to initiate head formation in a host increases with the time allowed for regeneration before grafting, while the foot-initiating ability decreases concomitantly. The reverse was found for tissue about to regenerate a foot. The early divergent changes thus indicated are counteracted in both head and foot regeneration by treatment with an inhibitor (Berking, 1977) in low concentrations.The inhibitor also interferes with processes which determine wether or not hypostome and tentacles are formed, and how many tentacles (if any) appear. The circumferential spacing of the tentacles was regular whether their number was normal or below normal.Secondary axes caused by implanted tissue either detach after having formed a head and a foot (i.e. behave like buds) or do not detach, having only formed a head. This alternative depends on the origin and amount of the implanted tissue and on the position of the implant within the host.The following model based on these findings is proposed: Head and foot formation start with pre-patterns which cause a continuously increasing change of the tissue's ability to initiate a head or a foot. Along the body axis this ability is determined by a graded distribution of sources. As development progresses, the high source density which accumulates in the head region causes the formation of a hypostome and tentacles; the angular spacing of tentacles is also dependent on source density. At a certain low source density foot-formation is initiated. The inhibitor counteracts the increase of source density in head-forming tissue as well as the decrease of source density in foot-forming tissue. It thus appears to be part of the mechanism which controls morphogenesis in hydra.     

Analysis of the human and ape foot during bipedal standing with implications for the evolution of the foot

The ratio of the power arm (the distance from the heel to the talocrural joint) to the load arm (that from the talocrural joint to the distal head of the metatarsals), or RPL, differs markedly between the human and ape foot. The arches are relatively higher in the human foot in comparison with those in apes. This study evaluates the effect of these two differences on biomechanical effectiveness during bipedal standing, estimating the forces acting across the talocrural and tarsometatarsal joints, and attempts to identify which type of foot is optimal for bipedal standing. A simple model of the foot musculoskeletal system was built to represent the geometric and force relationships in the foot during bipedal standing, and measurements for a variety of human and ape feet applied. The results show that: (1) an RPL of around 40% (as is the case in the human foot) minimizes required muscle force at the talocrural joint; (2) the presence of an high arch in the human foot reduces forces in the plantar musculature and aponeurosis; and (3) the human foot has a lower total of force in joints and muscles than do the ape feet. These results indicate that the proportions of the human foot, and the height of the medial arch are indeed better optimized for bipedal standing than those of apes, further suggesting that their current state is to some extent the product of positive selection for enhanced bipedal standing during the evolution of the foot.     

Crossover replantation and fillet flap coverage of the stump after ectopic implantation: a case of bilateral leg amputation

A successful case of crossover replantation of the left foot to the stump of the right leg and temporary ectopic implantation of the right amputated foot on the forearm is described. The ectopically implanted right foot was used as a free fillet flap for the late reconstruction of the left leg stump. At the latest follow-up examination, 18 months after the accident, the patient was able to walk independently with a prosthesis on the stump of the left leg. Both the cross-replanted foot and the free filleted foot flap, used for the reconstruction of the left leg stump, have maintained adequate protective sensation. The importance of utilization of amputated parts for functional reconstruction is stressed. Crossover replantations and ectopic implantations should be considered in bilateral amputations for the salvage of at least one extremity.     

Successful replantation in the face of absent venous drainage: an experimental study

Inadequate venous outflow is the factor most responsible in digital replantation failure and is a common cause of tissue loss in general. An experimental replantation model utilizing the rabbit ear was used to study the extreme example of venous congestion: absent venous drainage in the replanted part. Results of this study support the use of single arterial inflow along with an efferent AV fistula for outflow in the management of replants with absent venous drainage. Potential indications for the use of an efferent arteriovenous fistula in digital revascularization include the following: (1) the finding of distal veins too small to reanastomose, as is often the case in children and at distal levels in adults; (2) preferential destruction of distal venous structures, as commonly seen in degloving or other dorsal injuries; and (3) in the management of postreplant venous thrombosis.     

The influence of foot position on body dynamics

During locomotion, the human body exhibits inherent dynamic properties such as mass (M), stiffness (K) and damping (B). During the gait cycle, foot contact with the ground progresses from the heel to the toe. Contact forces between the foot and ground are defined as ground reaction forces (GRF). It is unclear how body dynamics are affected by foot landing position. If the shape of GRF is indicative of body dynamics, our understanding of gait patterns in normal and pathologic conditions may improve. The aims of this study were to determine:(1) whether foot landing position affects the inherent dynamics of the human body and (2) the extent to which the GRF curve reflects the response of inherent body dynamics to sudden loading.Eight non-disabled control volunteers performed a series of small jumps and landed on one leg with a fully extended knee in three foot landing positions: heel, mid-foot, and toe. They then walked at self-paced velocity over force plates. For each foot landing position, values of K, B and the dimensionless damping coefficient, ξ, were calculated from the period of vertical body oscillations, T, and compared with an ANOVA test. In addition, the time between the two peaks of the vertical GRF, T_GRF, was compared with T. We found that that K and B decreased and ξ did not change (p<0.01) between heel to toe-landing positions. T_GRF was not different than T for the toe-landing position, which suggests that the dynamic body response has major impact on the shape of GRF.     

Effects of leg activity and ambient barometric pressure on foot swelling and lower-limb skin temperature during 8 h of sitting

Prolonged immobilization in an upright position often leads to discomfort and oedema in the feet of otherwise healthy subjects. To determine the significance of leg activity and ambient pressure on oedema formation, skin temperature (Tsk) and discomfort, 6 volunteers sat for 8 h with one leg immobilized and the other spontaneously active; one day at "sea level" (750 mmHg) and one day at reduced barometric pressure (540 mmHg). Foot swelling was measured by water plethysmography. Leg movements were continuously monitored by a Vitalog computer, and foot discomfort was estimated by analog-visual scales. The 8 hour swelling averaged 5.7% in the inactive foot, and 2.7% in the active foot (p less than 0.001). Tsk of the inactive foot levelled off towards ambient temperature (21 degrees C) within 4 h. For the active foot this fall was reduced by 2-3 degrees C (p less than 0.025). The increase in foot discomfort during the day was lowest in the active foot (p less than 0.005). High foot Tsk was associated with a high foot swelling rate. Reduced ambient barometric pressure had no effects on foot swelling or Tsk. It is concluded that modest leg activity during 8 h of sitting has several effects on the circulation in the feet: some effects promote and some prevent oedema formation. However, the net result is a reduction in foot swelling.     

The functional morphology of the abyssal Limopsis cristata (Arcoida: Limopsidae) with a discussion on the evolution of the more advanced bivalve foot

The bivalve Limopsis cristata pursues a semi‐endobenthic life in abyssal soft sediments. It attaches to particles by up to three byssal threads and filter feeds by inhaling water from posterior and anterior directions. Because of partial burial, however, only the latter is functionally significant. Complex ciliary currents in the mantle cavity concerned with the rejection of unwanted particles keep most material out of the simplified intestine. It is generally considered that the ligament is the constraining force in arcoid evolution. This may be true in part, but the lack of pallial fusions and the retention of anterior and posterior inhalant flows are more powerful limits to radiation in the Arcoida. In the deep sea, the Limopsidae has radiated into many micro‐niches through micro‐morphological adaptations. Loss of the arcoid ‘heel’ has resulted in the union of the separate rejectory currents of the visceral mass and foot, creating a single discharge point in more advanced bivalves. This greatly simplifies the rejectory roles of the visceral mass and foot and is thus of functional and selective advantage.     

Effects of alcohol and coca on foot temperature responses of highland Peruvians during a localized cold exposure

Two groups of highland Quechua Indian males were tested under conditions of local foot exposure to cold air (0°C). Foot temperatures were monitored throughout the hour cold test and for 16 minutes recovery at room temperature (24°C). In the first group (age range 14–20 years), 29 subjects were tested while chewing coca leaves and while under control conditions. The second group (age range 20–50 years) of 25 subjects was tested while consuming 1.1 gm of ethyl alcohol per kilogram of body weight and again under control conditions. Both drugs (coca and alcohol) are habitually consumed by members of the native population. The mastication of coca leaves had no effect on foot skin temperatures. Alcohol consumption, however, elevated foot temperatures to between 4 and 6°C higher than control values at the end of 60 minutes of cold exposure. It is suggested that alcohol consumption gives the Indian a slight thermal advantage and increases levels of comfort during natural cold exposure.     

Salvage of the mutilated upper extremity with temporary ectopic implantation of the undamaged part

A method of salvage of mutilated extremities with temporary ectopic implantation of the undamaged distal part is described. We suggest that this method is indicated in devastating segmental injuries of extremities, where the distal part is devascularized and where a necessary radical debridement would include the structures which are indispensable for a good functional result of the replantation but which would possibly survive if treated with an open-wound technique. The method could also be used in cases where an essential length of limb could be preserved by open-wound management with improvement of the functional and aesthetic result of replantation. The method is contraindicated in injuries where perfusion of the distal part is preserved. The lateral upper part of the thorax is suggested as a convenient site, with the thoracodorsal artery and vein as recipient vessels. The timing of replantation of the ectopic implanted part must be carefully planned to avoid complications caused by remaining necrotic tissues or infection. The importance of intensive physiotherapy of the ectopic implanted part is stressed.     

The control of foot formation in transplantation experiments with hydra viridis

The results of three groups of experiments on the control of foot (basal disk) differentiation in Hydra viridis are well'; predicted by mathematical models of remarkable simplicity. In each of the experiments, a group of cells, called the actor, may or may not form a foot. The probability of foot formation is influenced by actor-specific properties and by properties of the rest of the animal, which may be called the setting.A natural interpretation of the mathematical models is that the actor forms a foot or not according to the balance of an inhibition of foot formation determined by the setting, and a critical inhibition level or “threshold”, an assumed actor characteristic. Threshold and inhibition are assumed to be normal random variables, the means of which depend on the parameters of the experiment. A foot is assumed to form in an individual case if the threshold is greater than, the inhibition.When transformed to a probit or logit scale, as described in the text, the mean intensity of inhibition appears to increase linearly with the quantity of foot tissue and to decrease linearly with increasing distance from the foot end of the hydra's body axis. The mean level of the threshold appears to increase linearly with time during which actor tissue is removed from inhibitory influences, but varies nonlinearly with position within the hydra.The inhibition-threshold models are tested here through statistically more tractable but numerically indistinguishable models of different mathematical form. If interpreted directly these models suggested that the odds that a foot will form are the product of an actor-determined scalar and a setting-determined scalar. The logarithms of these scalars are linear functions of the experimental parameters.     

Diabetic foot infections: fate of the contralateral foot

Following an initial report urging conservative management of severe diabetic foot infections, the authors have managed 45 patients with a minimum 3-year follow-up. By using standard principles for soft-tissue infection, 78 percent of the patients healed minor amputation sites and maintained biped ambulation following the initial foot involvement. Only 22 percent required a major amputation at the time of the initial foot involvement. The 45 patients were followed and 22 (or 49 percent) developed a severe infection involving the contralateral foot within 18 months. Although 15 of the 22 patients developing contralateral infection (or 33 percent of the total series) required some type of amputation on the contralateral foot, the conservative approach allowed 64 percent of the patients with severe infections in both feet to maintain biped ambulation. This included 40 percent of the patients who required amputation of some portion of both feet.     

A comparative study of the composition of the collagens of the foot of two lamellibranch molluscs occurring in different habitats

A comparative study of the collagen of the foot ofLamellidens Sp. and that of the unmodified part of the foot inMytilus edulis shows marked differences in physical properties, amino acid composition and in the degree of stabilization. But both conform to type I collagen of vertebrates. In these respects, the latter shows agreement with the features characteristic of byssus collagen, which is highly crosslinked, involving dimers and trimers of tyrosine. It is suggested that such differences may reflect the different functions of the organs concerned, the foot ofLamellidens being a locomotary organ of the animal, while the foot ofMytilus edulis is modified for anchorage of the animal. The vertigial part though not morphologically modified shows the essential compositional characteristics of the byssus being a mere remanant of it. The work reported forms part of the thesis approved by the University of Madras for the award of the Ph.D. degree to the first author.     

Identification and characterization of hydra metalloproteinase 2 (HMP2): a meprin-like astacin metalloproteinase that functions in foot morphogenesis

Several members of the newly emerging astacin metalloproteinase family have been shown to function in a variety of biological events, including cell differentiation and morphogenesis during both embryonic development and adult tissue differentiation. We have characterized a new astacin proteinase, hydra metalloproteinase 2 (HMP2) from the Cnidarian, Hydra vulgaris. HMP2 is translated from a single mRNA of 1.7 kb that contains a 1488 bp open reading frame encoding a putative protein product of 496 amino acids. The overall structure of HMP2 most closely resembles that of meprins, a subgroup of astacin metalloproteinases. The presence of a transient signal peptide and a putative prosequence indicates that HMP2 is a secreted protein that requires post-translational processing. The mature HMP2 starts with an astacin proteinase domain that contains a zinc binding motif characteristic of the astacin family. Its COOH terminus is composed of two potential protein-protein interaction domains: an "MAM" domain (named after meprins, A-5 protein and receptor protein tyrosine phosphatase mu) that is only present in meprin-like astacin proteinases; and a unique C-terminal domain (TH domain) that is also present in another hydra metalloproteinase, HMP1, in Podocoryne metalloproteinase 1 (PMP1) of jellyfish and in toxins of sea anemone. The spatial expression pattern of HMP2 was determined by both mRNA whole-mount in situ hybridization and immunofluorescence studies. Both morphological techniques indicated that HMP2 is expressed only by the cells in the endodermal layer of the body column of hydra. While the highest level of HMP2 mRNA expression was observed at the junction between the body column and the foot process, immunofluorescence studies indicated that HMP2 protein was present as far apically as the base of the tentacles. In situ analysis also indicated expression of HMP2 during regeneration of the foot process. To test whether the higher levels of HMP2 mRNA expression at the basal pole related to processes underlying foot morphogenesis, antisense studies were conducted. Using a specialized technique named localized electroporation (LEP), antisense constructs to HMP2 were locally introduced into the endodermal layer of cells at the basal pole of polyps and foot regeneration was initiated and monitored. Treatment with antisense to HMP2 inhibited foot regeneration as compared to mismatch and sense controls. These functional studies in combination with the fact that HMP2 protein was expressed not only at the junction between the body column and the foot process, but also as far apically as the base of the tentacles, suggest that this meprin-class metalloproteinase may be multifunctional in hydra.     

Effect of body and foot positions on the somatosensory evoked potentials

Somatosensory evoked potentials in response to stimulation of the posterior tibial nerve at the ankle were recorded during sitting and standing with variable foot positions. During standing a decrease in the amplitude of the early positive component was observed. The deviation of the foot from a horizontal position was associated with an increase in the amplitude of the early negative component. The combined influence of body and foot positions showed a decrease in the amplitude of both early and late components. The standing position induced changes in more components than the varied foot positions. This suggests that maintenance of the standing posture is a more complex task than the maintenance of the foot position itself.     

Regeneration of proximal and distal part of hydra body cut in the middle of gastral cavity and treated with dactinomycine

Hydras were cut in the middle of the gastral part of the body. The part with the hypostome is marked as H, and the one with the foot as P. Both parts were treated with actinomycine D in 0,5 mg : 200 ml water solution. H-parts are much more sensitive to the effect of actinomycine than P-parts, and P lives considerably longer. It is supposed that such reaction are the result of specificity of H and P cell composition, and of the growth direction which is characteristic of hydra in general. H-part has a proportionally greater number of differentiated cells and this relatively smaller number of non-differentiated cells is spent in it quicker than in P-part in which they are more numerous. The growth direction has a decisive influence on further life of H- respectively P-part. Namely, H- in growth direction does not have any damaged body regions (hypostome and tentacles are intact) and it lacks the amputated P-part i.e. gastral region with foot: the region which is on the opposite side of growth direction of hydra. H-part has all the characteristic cells of this body region, so after amputation mostly it does not change. Unfavourable effect of citostatic manifests sooner and H-part desintegrates quicker. On the contrary, P-part lacks the hypostome with tentacles, and these are the body parts in the growth direction. Zimogen cells can dedifferentiate and differentiate. The hypostome and tentacles regenerate as far as is allowed by actinomycine.