The ability of oxygenated fluorocarbon solution to minimize ischemic skeletal muscle injury

The amputated canine limb was used to create a devascularized skeletal-muscle-containing model. The extremity was perfused with one of several solutions or merely cooled as a preservative measure during the devascularized period and then replanted. Perfusion of the limb with oxygenated fluorocarbon solution minimized edema formation and leakage of skeletal muscle enzymes into the serum following revascularization as compared to the other perfusates or to mere cooling. Histopathologic changes within the revascularized muscle were also minimized by the oxygenated fluorocarbon perfusion. It is probable that these findings will correlate with improved function of replanted extremities or free muscle flaps. The applicability of these findings to human extremity replantation and free-flap transfer is postulated. However, long-term human studies will be necessary to assess the function of extremities and flaps perfused with this solution prior to its general use in extremity replantation and free-flap transfer.     

Successful replantation of an amputated leg in a child.

We report the successful replantation of an amputated leg in a 4-year-old boy. Four years after the replantation, skeletal growth and nerve regeneration were good and he had an excellent recovery of function and appearance. This result was undoubtedly enhanced by his youth, the ideal conditions for nerve repair, and the good preservation of the amputated leg in ice water. Replantation of an amputated lower extermity should be tried if the conditions mentioned above are fulfilled.     

A monoclonal antibody detects a difference in the cellular composition of developing and regenerating limbs of newts

We have previously described a monoclonal antibody (called 22/18) that reacts with the early blastemal cells of the regenerating limb of the newt (Notophthalmus viridescens). In embryos of two newt species the antibody reacts with the epidermis, glial cells in the neural tube, the lens and cells in a restricted region of the aorta. In the developing limb bud less than 1% of the mesenchymal cells were reactive with 22/18, although most cells stained brightly with an antibody to another cytoskeletal component. When limbs were amputated prior to the arrival of nerves (axons and Schwann cells) at the amputation plane there was no extra reactivity with 22/18 as compared to the contralateral unamputated control, even though the amputated buds regenerated satisfactorily. Limbs amputated after nerves are present at the plane of amputation respond by forming a 22/18-positive blastema. The appearance of the 22/18 responses is a function of the stage of limb development as shown by amputation of forelimb and hindlimb buds at a larval stage where development of the forelimb is greatly advanced relative to the hindlimb. The distribution of the 22/18-positive cells in larval blastemas showed them to be closely associated with axons as detected by double staining with an antiserum to a neurofilament subunit. The clear antigenic difference between development and regeneration may be related to the relationship between embryonic regulation and epimorphic regeneration, and also to the acquisition of nerve-dependent proliferation of blastemal cells.     

Spinal cord atrophy and reorganization of motoneuron connections following long-standing limb loss in primates

Primates with long-standing therapeutic amputations of a limb at a young age were used to investigate the possibility that deefferented motor nerves sprout to new muscle targets. Injections of anatomical tracers into the muscles proximal to the amputated stump labeled a larger extent of motoneurons than matched injections on the intact side or in normal animals, including motoneurons that would normally supply only the missing limb muscles. Although the total numbers of distal limb motoneurons remained normal, some distal limb motoneurons on the amputated side were smaller in size and simpler in form. These results suggest that deprived motoneurons survive and retain function by reinnervating new muscle targets. The sprouted motor efferents may account for some of the reorganization of primary motor cortex that follows long-standing amputation.     

The effect of healing time on the proximodistal organization of double-half forelimb regenerates in the axolotl,Ambystoma mexicanum

The effect of healing on the proximodistal organization of regenerates from double-half forelimbs was studied. Double-anterior and double-posterior upper forelimbs were prepared surgically and amputated at 5, 10, 15, 20, 30, and 60 days after grafting. All experimental groups regenerated hypomorphic skeletal patterns. Double-half forelimbs amputated at Days 5 and 10 regenerated more distally complete skeletal patterns than did limbs amputated at Days 30 and 60. The mean numbers of skeletal elements regenerated were seen to decrease as a function of time after grafting, with the maximal suppression of skeletal patterns observed to occur when limbs were amputated 30 days following grafting. There was no appreciable difference between limbs amputated at Days 30 and 60. These results suggest that healing time has a profound effect on the proximodistal organization of limbs regenerated from double-half forelimb stumps.     

Studies on regeneration of central nervous system and social ability of the earthworm <Emphasis Type="Italic">Eudrilus eugeniae</Emphasis>

Earthworms are segmented invertebrates that belong to the phylum Annelida. The segments can be divided into the anterior, clitellar and posterior parts. If the anterior part of the earthworm, which includes the brain, is amputated, the worm would essentially survive even in the absence of the brain. In these brain amputee-derived worms, the nerve cord serves as the primary control center for neurological function. In this current work, we studied changes in the expression levels of anti-acetylated tubulin and serotonin as the indicators of neuro-regenerative processes. The data reveal that the blastemal tissues express the acetylated tubulin and serotonin from day four and that the worm amputated at the 7th segment takes 30 days to complete the regeneration of brain. The ability of self-assemblage is one of the specific functions of the earthworm’s brain. The brain amputee restored the ability of self-assemblage on the eighth day.     

The influence of muscle flap coverage on the repair of devascularized tibial cortex: an experimental investigation in the dog

Segments (2 cm) of canine tibial diaphyseal bone were devascularized and internally fixed with a plate. The medial cortex of the devascularized tibia was covered with skin in one experimental group (n = 7) and a local muscle flap in the other (n = 6). The animals were given intravenous fluorochrome dye and killed 42 days postoperatively. Enveloping callus formed around the cortex which was repaired by the formation of resorptive cavities on its external surface. New bone formation occurred within the resorptive cavities. Muscle flap coverage was associated with a sixfold increase in cortical porosity (p less than 0.005) and a fourfold increase in the area of enveloping callus (p less than 0.05). The area of intracortical new bone formation was greater in the cortex with muscle flap coverage (p less than 0.05). The maximum depth of intracortical new bone formation increased from 0.46 +/- 0.14 mm with skin coverage to 0.95 +/- 0.14 mm with muscle flap coverage (p less than 0.001). This study demonstrates that muscle flaps are superior to skin coverage in initiating the repair of devascularized cortical bone.     

Reconstruction of fingertip amputations with full-thickness perionychial grafts from the retained part and local flaps.

The treatment of fingertip amputations distal to the distal interphalangeal joint when the amputated part is saved is difficult and controversial. Both reattachment of the amputated portion as a composite graft and microvascular anastomosis are prone to failure in this distal location. The authors have evolved a reconstructive plan that uses the nail matrix, perionychium, and hyponychium of the amputated fingertip as a full-thickness graft when the amputation is between the midportion of the nail bed andjust proximal to the eponychial fold. Various flaps are used to lengthen and augment the finger pulp, and skeletal pinning is carried out as necessary. The charts of 15 patients who underwent this procedure over a 38 month period were evaluated retrospectively. Seven returned to the office for examination at least 1 year after the fingertip reconstruction described above; four others were interviewed by telephone. Nail deformity, fingertip sensation, and joint range of motion were evaluated, and the reconstructed fingertips were photographed in standardized views. In six of the seven patients seen in the office, aesthetic and functional results were judged as good by both patient and physician; one of the six had minimal nail curvature. The seventh patient had no nail growth, although finger length was retained and there was no functional disability. The four patients interviewed by phone reported normal fingertip use with no dysesthesias or cold intolerance; all had nail growth, although three patients described slight nail curvature that required care in trimming. The authors favor salvage of all perionychial parts when a distal fingertip amputation occurs. Reconstruction of the fingertip with grafting of the hyponychium, perionychium, and nail matrix from the amputated part combined with local flaps can provide a very satisfactory functional and aesthetic result.     

The regeneration capacity of an earthworm, Eisenia fetida, in relation to the site of amputation along the body

It is well known that parts of earthworms can survive if they are cut off. Our aim was to link the regeneration capacity of an earthworm, Eisenia fetida (Oligochaeta, Annelida) with the site of the amputation, so we amputated earthworms at different body segment locations along the length of the body to examine the different survival rates and regeneration lengths of the anterior, posterior, and medial sections.
The greatest survival rates occurred for earthworms with the most body segments remaining after amputation. The anterior regeneration lengths were of two types. The lengths of regeneration of amputated from body segment 6/7 to further down the body posteriorly increased gradually (Type L_I). However, the regeneration lengths of earthworm which were amputated behind the 23rd segment, with less than a quarter of the total segments remaining, did not increase until the blastema and tail bud formation (Type L_II). These treatments were not completely regeneration. There were significant differences in both survival rates and lengths of regeneration lengths between immature earthworms and clitellate adult earthworms during the early stages of regeneration, but not at later stages of regeneration. The immature earthworms had a greater regeneration potential than clitellate adults amputated at the same segment. The survival rates of earthworms were correlated significantly with the number of body segments remaining after amputation, but not with the position of the amputation. The relationships between the survival rates and the numbers of remaining segments could be described by linear regressions. The anterior regeneration lengths were correlated with the position of the amputation, but not with the number of remaining segments; the posterior regeneration lengths, were not correlated with the number of segments remaining nor the amputation position. The anterior regeneration length was not related to the survival rates for all earthworm amputations after 30 days but was related in this way after 60 days.     

The regeneration capacity of an earthworm, Eisenia fetida, in relation to the site of amputation along the body

It is well known that parts of earthworms can survive if they are cut off. Our aim was to link the regeneration capacity of an earthworm, Eisenia fetida (Oligochaeta, Annelida) with the site of the amputation, so we amputated earthworms at different body segment locations along the length of the body to examine the different survival rates and regeneration lengths of the anterior, posterior, and medial sections.
The greatest survival rates occurred for earthworms with the most body segments remaining after amputation. The anterior regeneration lengths were of two types. The lengths of regeneration of amputated from body segment 6/7 to further down the body posteriorly increased gradually (Type L_I). However, the regeneration lengths of earthworm which were amputated behind the 23rd segment, with less than a quarter of the total segments remaining, did not increase until the blastema and tail bud formation (Type L_II). These treatments were not completely regeneration. There were significant differences in both survival rates and lengths of regeneration lengths between immature earthworms and clitellate adult earthworms during the early stages of regeneration, but not at later stages of regeneration. The immature earthworms had a greater regeneration potential than clitellate adults amputated at the same segment. The survival rates of earthworms were correlated significantly with the number of body segments remaining after amputation, but not with the position of the amputation. The relationships between the survival rates and the numbers of remaining segments could be described by linear regressions. The anterior regeneration lengths were correlated with the position of the amputation, but not with the number of remaining segments; the posterior regeneration lengths, were not correlated with the number of segments remaining nor the amputation position. The anterior regeneration length was not related to the survival rates for all earthworm amputations after 30 days but was related in this way after 60 days.     

Replantation of fingertip amputation by using the pocket principle in adults

There are several treatment modalities for zone 1 or zone 2 fingertip amputations that cannot be replanted by using microsurgical techniques, such as delayed secondary healing, stump revision, skin graft, local flaps, distant flaps, and composite graft. Among these, composite graft of the amputated digit tip is the only possible means of achieving a full-length digit with a normal nail complex. The pocket principle can provide an extra blood supply for survival of the composite graft of the amputated finger by enlarging the area of vascular contact. The surgery was performed in two stages. The amputated digit was debrided, deepithelialized, and reattached to the proximal stump. The reattached finger was inserted into the abdominal pocket. About 3 weeks later, the finger was removed from the pocket and covered with a skin graft. We have consecutively replanted 29 fingers in 25 adult patients with fingertip amputations by using the pocket principle. All were complete amputations with crushing or avulsion injuries. Average age was 33.64 years, and men were predominant. The right hand, the dominant one, was more frequently injured, with the middle finger being the most commonly injured. Of the 29 fingers, 16 (55.2 percent) survived completely and 10 (34.5 percent) had partial necrosis less than one-quarter of the length of the amputated part. The results of the above 26 fingers were satisfactory from both functional and cosmetic aspects. Twenty of the 29 fingers, which had been followed up for more than 6 months (an average of 16 months), were included in a sensory evaluation. Fifteen of these 20 fingers (75 percent) were classified as "good" (static two-point discrimination of less than 8 mm and normal use). From the overall results and our experience, we suggest that the pocket principle is a safe and valuable method in replantation of zone 1 or zone 2 fingertip amputation, an alternative to microvascular replantation, even in adults.     

Secondary expansion of a replanted scalp salvaged by an intrinsic arteriovenous shunt.

1. Although scalping injuries reported in most large series rarely involve young children, partial scalp replantation, even in a 2-year-old boy after a dog-bite avulsion, should also be warranted. However, technical difficulties because of the diminutive vasculature can be expected. 2. Unconventional methods for reestablishing inflow or outflow for the replanted scalp may become the only practical alternative and must not be overlooked. In this case, an arteriovenous shunt between the frontal branch of the superficial temporal artery within the amputated part itself to a more distal scalp vein at the superior edge of the fragment allowed high-output flow to maintain patency after recurrent thromboses of the conventional superficial temporal arterial anastomosis. This fistula was assumed to be the major contributor to nutrient flow of the remaining scalp, as the parietal branch was truncated along the margin of the avulsion. 3. Delayed tissue expansion is also an option. In this case, delayed expansion of the replanted scalp that survived allowed elimination of the skin grafts needed to cover areas where necrosis ensued, restoration of the anterior hairline, and resulted in a more normal appearance.     

Necessity of an adequate nerve supply for regeneration of the amputated pectoral fin in the teleost Fundulus

The present work deals with determination of the threshold of nerve fibers per unit of amputation surface necessary for regeneration of the pectoral fins of a teleost, Fundulus. Partial denervation of the amputated pectoral fins, i.e., resection of one or two of the three nerves of the brachial (=pectoral) plexus revealed that the presence of a single one allows the amputated fin to regenerate. From these data and others obtained previously, it is concluded that the nervous requirements for a teleost fin to regenerate are similar or slightly lower than those for tetrapods, for example in the newt, which are capable of appendage regeneration.     

三种华枝断肢再生的研究

目(竹节虫目)的昆虫具有很强的断肢再生能力。该文通过对华枝属(Sinophasma spp)三种昆虫的实验,表明其再生能力与断肢发生的时间及数量有关。断肢1只或2只的1～4龄虫体发育至成虫期或至若虫末龄时,其再生足的长度与相应的正常足长度相近。若在5龄初时断肢1～2只,也具有再生能力,但至成虫期其再生足的长度则短于相对应的正常足。若在6龄及成虫时断肢,则无再生能力（若6龄时出现断肢再生,则若虫期多为7龄）。实验结果还表明,若断肢为3只或3只以上,则虫体不能存活,且多在断肢后2～3 d内死亡。观察中尚发现,再生足生长速度明显高于正常足。而且,断肢的龄期越高,再生足生长速度越快。再生足的伸长生长与正常足一样,均出现于虫体蜕皮时。     

Autophagy is required for zebrafish caudal fin regeneration

Regeneration is the ability of multicellular organisms to replace damaged tissues and regrow lost body parts. This process relies on cell fate transformation that involves changes in gene expression as well as in the composition of the cytoplasmic compartment, and exhibits a characteristic age-related decline. Here, we present evidence that genetic and pharmacological inhibition of autophagy – a lysosome-mediated self-degradation process of eukaryotic cells, which has been implicated in extensive cellular remodelling and aging – impairs the regeneration of amputated caudal fins in the zebrafish (Danio rerio). Thus, autophagy is required for injury-induced tissue renewal. We further show that upregulation of autophagy in the regeneration zone occurs downstream of mitogen-activated protein kinase/extracellular signal-regulated kinase signalling to protect cells from undergoing apoptosis and enable cytosolic restructuring underlying terminal cell fate determination. This novel cellular function of the autophagic process in regeneration implies that the role of cellular self-digestion in differentiation and tissue patterning is more fundamental than previously thought.     

Experimental analysis of the ‘Paarkultureffekt’ in the protandric polychaete, Ophryotrocha puerilis Clap. Mecz.

Female Ophyrotrocha puerilis Clap. Mecz. were coupled. Certain parts of the prostomium and of the pygidium in one or both partners of a couple were amputated in order to prove that they are responsible for the mutual influence which partners normally exert on their sexual differentiation. The results demonstrate that the palps and the ventrolateral prostomial cirri are the transmitters and the ciliated lateral pits on the prostomium the receivers of the mutual influence. The antennae and the pygidial cirri are not necessary as far as the ‘Paarkultureffekt’ is concerned. The nature of the stimulus is still unknown. At the present stage of these investigations, the favoured conception is of a pheromone transmitted during the contact of the partners.     

Beliefs about genetic influences on mathematics achievement: a cross-cultural comparison

The poor mathematics performance of children in the United States has become a topic of national concern. Numerous studies have shown that American children consistently perform worse than their counterparts in many parts of the world. In contrast, children in China, Japan, Taiwan, and other Asian countries consistently perform at or near the top in international comparisons. This paper examines possible causes of the poor performance of American children and the excellent performance of Asian children. Contrary to the beliefs of many Americans, the East Asian advantage in mathematics is probably not due to a genetically-based advantage in mathematics. Instead, differences in beliefs about the role of genetics may be partly responsible. Asians strongly believe that effort plays a key role in determining a child's level of achievement, whereas Americans believe that innate ability is most important. In addition, despite the relatively poor performance of their children, American parents are substantially more satisfied with their children's performance than Asian parents. The American emphasis on the role of innate ability may have several consequences for children's achievement. For example, it may lead children to fear making errors and to expend less effort on mathematics than their Asian counterparts. As research on genetic influences on behavior, traits, and abilities increases scientists should be careful to ensure that the public understands that genetics does not directly determine the exact level of a child's potential achievement. This revised version was published online in August 2006 with corrections to the Cover Date.     

中华真地鳖断足再生对发育的影响

研究中华真地鳖EupolyphagasinensisWalker的断足时间及数量对发育历期的影响,以及不同龄期断足处理后发育历期间的差异。以8龄若虫为研究对象,发现其再生临界期为20~26日龄。不同日龄的8龄若虫断去1条后足,蜕1次皮后能再生的若虫从断足至蜕皮的平均时间与8龄的正常历期相近,整个8龄若虫的发育历期均比正常历期长,并随断足处理日龄的增加而逐渐增加。蜕1次皮后断足没有再生的绝大部分个体,8龄若虫的历期均比正常历期短。以3日龄的4龄若虫为处理对象,发现断去不同数量的足后(蜕1次皮后均能再生),从断足至蜕皮的历期及4龄的历期,均随虫体断足数量的增加而增加,但断去1条或2条后足处理,从断足至蜕皮的历期间及断足处理后4龄历期与正常历期间的差异不显著。不同虫龄的若虫断去1条后足的腿节后1次蜕皮后能再生的大部分个体,从断足至蜕皮的时间比同龄若虫的正常历期稍长,所延长的时间相当于从龄初至断足处理的时间,而断足后1次蜕皮未再生的其余个体从断足到蜕皮的时间均很短。     

Temporal analysis of the role of growth hormone in the initiation and maintenance of limb regeneration in the hypophysectomized newt Notophthalmus viridescens

This study was designed to investigate and determine for how long, after either hypophysectomy or the third (last) growth hormone injection (to previously hypophysectomized newts), the circulating and now declining titers of endogenous or exogenous hormone remained at a sufficient concentration to permit a morphologically normal forelimb regeneration response in the adult newt Notophthalmus viridescens. To examine the declining levels of endogenous hormone (hormone withdrawal series [HW]), left forelimbs were amputated at specific times following hypophysectomy. Right forelimbs were amputated 5 days prior to hypophysectomy. The declining levels of exogenous hormone (hormone replacement series [HR] were examined in newts whose left forelimbs were amputated at specific times following the last of three consecutive alternate-day growth hormone injections that were initiated 5 days post hypophysectomy. Right forelimbs were amputated immediately following the first hormone injection. All experimental animals were sacrificed when their right forelimbs regenerated to an advanced digitiform regenerate. In both series right forelimbs regenerated normally. In the HW series normal regeneration resulted only when forelimbs were amputated within 48 hours post hypophysectomy, whereas in the HR series normal regeneration occurred in only those newts whose forelimbs were amputated within 12 hours of the last hormone injection. The regeneration response of left forelimbs in both series gradually declined with the time interval between either hypophysectomy or hormone injection and forelimb amputation. As the hormone titer declined, fewer limbs initiated a normal response; they became progressively more hypomorphic and eventually failed to undergo typical regeneration.