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In free orthotopic auto-grafts of the extensor digitorum muscle of rats a marked temporary decrease of resting membrane potential (RMP) of two superficial layers of muscle fibres is observed at 2 days with subsequent recovery 4 days after transplantation. Such a temporary decrease of the RMP is not observed in grafts of denervated muscle. This difference in change of RMP is apparently related to a temporary marked decrease or loss of contractility observed in innervated but not denervated graft and may explain in part the relatively more successful grafting of denervated muscles.

The soleus or extensor digitorum longus muscles of young rats were freely grafted into the bed of the corresponding contralateral muscle. The grafts were of normal muscle or muscles which had been denervated for 14 days. Grafts of normal muscle were characterized by little or no contractile activity for the first 2???4 days after transplantation. In contrast, denervated grafts contracted weakly, but consistently, throughout this early period. The patterns of contraction were complex. In early transplants, the contractions were due entirely to surviving muscle fibers in the graft, and the contractile characteristics were those of denervated muscle fibers. After the first week, contractions of newly regenerating muscle fibers within the grafts were superimposed upon and later took over those from the fibers that survived the original transplantation. The contraction time approached those of the normal soleus or extensor muscles during the second month after grafting, and the grafts contracted like fast or slow muscles.

We analyzed the level of protein expression of two myogenic regulatory factors (MRFs), MyoD and myogenin, in senile skeletal muscles and determined the cellular source of their production in young adult (4??months old), old (24, 26, and 28??months old), and senile (32??months old) male rats. Immunoblotting demonstrated levels of myogenin ~3.2, ~4.0, and ~5.5 times higher in gastrocnemius muscles of 24-, 26-, and 32-month-old animals, respectively, than in those of young adult rats. Anti-MyoD antibody recognized two major areas of immunoreactivity in Western blots: a single MyoD-specific band (~43???45??kDa) and a double (or triple) MyoD-like band (~55???65??kDa). Whereas the level of MyoD-specific protein in the 43- to 45-kDa band remained relatively unchanged during aging compared with that of young adult rats, the total level of MyoD-like immunoreactivity within the 55- to 65-kDa bands was ~3.4, ~4.7, ~9.1, and ~11.7 times higher in muscles of 24-, 26-, 28-, and 32-month-old rats, respectively. The pattern of MRF protein expression in intact senile muscles was similar to that recorded in young adult denervated muscles. Ultrastructural analysis of extensor digitorum longus muscle from senile rats showed that, occasionally, the area of the nerve-muscle junction was partially or completely devoid of axons, and satellite cells with the features of activated cells were found on the surface of living fibers. Immunohistochemistry detected accumulated MyoD and myogenin proteins in the nuclei of both fibers and satellite cells in 32-month-old muscles. We suggest that the up-regulated production of MyoD and myogenin proteins in the nuclei of both fibers and satellite cells could account for the high level of MRF expression in muscles of senile rats.

The innervation pattern of skeletal muscles was studied in the normal and regenerating tail of Notophthalmus viridescens . Silver staining for nerve endings and histochemical localization of acetylcholinesterase (AChE) were used for light microscopy. In normal musculature, AChE positive reactions were localized at the ends of the muscle fibers where they are anchored on connective tissue septa by myotendinous junctions. At this level, silver staining shows nerve terminals forming endplates. During regeneration, positive reactions for AChE appear de novo as dense plates localized at the ends of the newly formed myotubes. The mechanisms involved in the localization of AChE on this surface seem to operate before previous local contacts by nerve terminals. From the ultrastructural data and immunohistochemical results with anti-laminin antibody, these observations suggest that regenerating muscle fibers determine a region of post-synaptic specialization in close relation with the organization of myotendinous regions and basement membrane formation. Nerve-muscle contacts appear at these levels at stage IV (15-20 days after amputation) in the stump and in the rostral part of the regenerate (transition zone). These nerve terminals are provided by the disorganized peripheral nervous system of the injured segment. In the regenerate a similar pattern of AChE reaction can be seen in every myotube, differentiating according to a rostro-caudal gradient. Innervation at the ends of the muscle fibers is in spatiotemporal relation with the exits of the ventral roots from the regenerating nerve cord as the regenerate continues to grow in length.

One aspect of tissue engineering of skeletal muscle involves the transposition and transplantation of whole muscles to treat muscles damaged by injury or disease. The transposition of whole muscles has been used for many decades, but since 1970, the development of techniques for microneurovascular repair has allowed the transplantation of muscles invariably result in structural and functional deficits. The deficits are of the greatest magnitude during the first month, and then a gradual recovery results in the stabilization of structural and functional variables between 90 and 120 days. In stabilized vascularized grafts ranging from 1 to 3 g in rats to 90 g in dogs, the major deficits are ∼25% decrease in muscle mass and in most grafts ∼40% decrease in maximum force. The decrease in power is more complex because it depends on both the average shortening force and the velocity of shortening. As a consequence, the deficit in maximum power may be either greater or less than the deficit in maximum force. Tenotomy and repair are the major factors responsible for the deficits. Although the data are limited, skeletal muscle grafts appear to respond to training stimuli in a manner no different from that of control muscles. The training stimuli include traditional methods of endurance and strength training, as well as chronic electrical stimulation. Transposed and transplanted muscles develop sufficient force and power to function effectively to: maintain posture; move limbs; sustain the patency of sphincters; partially restore symmetry in the face; or serve as, or drive, assist devices in parallel or in series with the heart.

Expression of adult-type nicotinic acetylcholine receptors at the neuromuscular junction is thought to result from selective induction of their genes in endplate-associated nuclei due to local neurotrophic control. However, denervation studies indicate that endplate-specific expression can be maintained in the absence of the nerve. We investigated the role played by the basal lamina in this expression by assaying for the adult-type-specific [var epsilon] RNA in noninnervated regenerating muscle. We found that this RNA is locally expressed beneath the old endplates after 10 days of regeneration. At earlier times [var epsilon] RNA is also found in areas other than the endplate region. These results indicate that in adult muscle the basal lamina contains all the components necessary to direct nicotinic acetylcholine receptor gene expression to the endplate.

Pieces of cardiac ventricular tissue of late embryonic or 1-day postnatal rats, implanted beneath the kidney capsule of adult syngeneic hosts, formed viable, beating transplants. these transplants were investigated over a 40-day postoperative course. In the transplants, cellular binucleation and nuclear polyploidization occurred according to the same schedule as in the heart in situ. The composition of the classes of myocytes was identical both in the hearts in situ and in transplants, but the number of non-diploid myocytes in the intact heart reached 90%, whereas in transplants it varied from 30 to 60%. In contrast to the heart in situ, myocytes in transplants grew feebly after the phase of polyploidization. From these data one can conclude that under conditions of transplantation the temporal sequence of cellular binucleation and nuclear polyploidization follows the normal course, but that a greater number of myocytes remain in a diploid state than is the case in the normal heart. The growth of cardiac myocytes seems to be related to their level of function.

A conjunction error is a judgment that a conjunctive event is more likely than one of the marginal events comprising the conjunction. Previous research has demonstrated conjunction errors in situations in which marginal events arose from a common generating process. In Studies 1-3, conjunction errors were reliably induced in cases where marginal events resulted from unrelated processes. This suggests that conjunction errors can be produced by "formalistic" judgment procedures, by which probability judgments for conjunctions are derived from probability judgments for marginal events according to some combination rule. Protocols from Studies 2 and 3 also indicated that subjects use multiple judgment procedures, several of which are capable of yielding conjunction errors. One new procedure suggested by the protocols is formalized in a "signed sum model." In this model, an event's likelihood is represented by a positive number, a negative number, or zero, depending on whether the event is considered likely, unlikely, or neither, respectively. The likelihood value for a conjunction is the sum of those for the constituent marginal events. In Study 4, this model successfully predicted when some subjects made zero, one, or two conjunction errors.

Extensor digitorum longus muscles of rats were removed and injected with a solution of Marcaine plus hyaluronidase. After incubation in Marcaine solution for 10 min, the muscles were grafted into their original beds. The grafts and the contralateral control muscles were removed from the rats at 0, 1-5, 7, 11, 36, and 69 days postoperatively. The muscles were then frozen in dry ice and isopentane and subsequently homogenized and centrifuged. The supernatant was analyzed for a number of enzymes, the regenerative patterns of which can be classified into 3 groups: (1) early increase in activity: hexokinase, glucose-6-phosphate dehydrogenase; (2) early decrease in activity with failure to recover to control levels: phosphorylase, phosphofructokinase, [alpha]-glycerophosphate dehydrogenase; and (3) early decrease followed by return to control levels: lactate dehydrogenase, pyruvate kinase, creatine phosphokinase, adenylate kinase. These patterns are not identical to those reported for embryogenesis of muscle. The data are discussed with regard to correlative histological studies of muscle regeneration.

In order to compare the regenerative ability of skeletal muscle between young (5 month) and old (26 month) rats, sliced or intact extensor digitorum longus muscles were freely autografted into young and old rats and also reciprocally grafted from young to old inbred animals and vice versa. Sixty days after grafting, the transplants were analyzed for contractile and histochemical properties. There was a relative similarity between the contraction times of both normal control muscles and of all groups of transplants, although the contraction time tended to be prolonged and histochemical fiber pattern was more often found to be uniform in grafts of senescent animals. All groups of transplants possessed histochemically heterogeneous fiber types at 60 days. The experiments demonstrate that skeletal muscle in old rats possesses a substantial degree of regenerative ability and that the free tranpllantation of entire muscles in old animals is feasible.

Whole 3 g extensor digitorum longus (EDL) muscles of cats were autotransplanted. The EDL muscles were either transplanted without denervation prior to transplantation (normal transplants) or denervated 3 to 4 weeks prior to transplantation (pre-denervated transplants). A few peripheral skeletal muscle fibers survived transplantation but most fibers degenerated and then regenerated as the transplant became revascularized. Both normal and pre-denervated muscles regenerated successfully and by 50 days after transplantation fibers which had reinnervated showed high and low myofibrillar ATPase activity. Compared to controls, the smaller mean fiber cross-sectional area of the transplants was due to the large number of small fibers, but some fibers in the transplant were larger than any fibers observed in the controls. Transplants regained 57 percent of the muscle mass of the controls. Contraction and half relaxation times of transplanted muscles were slower than controls, but peak isometric tetanus tension per cm2 of muscle was nearly normal. Fifty to 170 days after transplantation, muscles showed low oxidative capacity and fatigued rapidly.

Soleus muscles in the rat were freely grafted alongside a normal soleus muscle in the absence of mechanical trauma to any of the surrounding muscles or motor nerves. The object of this experiment was to determine whether or not the muscle grafts would become reinnervated under these circumstances. Contractile and histochemical properties of the grafts were compared with those of the contralateral denervated soleus as well as normal muscles. Innervation of the grafts did occur, and it was concluded that the innervation of the grafts arose primarily from sprouts from nerves supplying neighboring muscles. The grafts were studied with specific nerve stains, histochemical techniques and by analysis of their contractile properties.

Rat extensor digitorum longus muscles were transversely sliced into 7-8 segments. The muscle slices were autografted back into their original beds. In one series the recipient limbs were normal and in the other, limbs were denervated. At postoperative intervals of 7, 14, 30, and 60 days, the contractile properties (Latency period, contraction and half relaxation times, time parameters of contraction of twitch and tetanus, and twitch and tetanic tension) and histochemical properties (succinic dehydrogenase and myofibrillar ATPase) were analyzed. Sliced grafts regenerating in normally innervated legs followed a typical conversion from slow to fast contraction times, whereas regenerates in denervated limbs remained slow. Histochemically, innervated regenerates developed a heterogeneous pattern of muscle fiber type staining during the second month, whereas different histochemical types of muscle fibers did not appear in noninnervated regenerates. As in ontogeny, denervation retards or prevents the full structural and functional differentiation of regenerating muscle fibers.

PURPOSE. This Coastal and Hydraulics Engineering Technical Note (CHETN) summarizes and updates the progress of the US Army Corps of Engineers National Regional Sediment Management (RSM) Demonstration Program(DP) implemented in Fiscal Year 2000 (FY00). Sediment management at the regional scale is discussed, followed by information on each of the demonstration projects currently underway with informative sections regarding regional economics and benefits of RSM. BACKGROUND. Regional sediment management, in a very general sense, fits sediment management actions into the context of a regional plan. Sediment management actions are activities that affect the erosion or removal, transport, and deposition of sediment. Common actions include: (1) dredging and placement, (2) building structures that divert or trap sediment, and (3) creating erosion protection for banks, shorelines, seabeds, and channel bottoms. A region is a defined area over which the sediment management actions will have a cumulative impact within the given time period of interest and with regard to the objectives of the plan (Figure 1). The plan is an accepted set of goals and objectives compiled by a region s stakeholders to be accomplished by the set of sediment management actions. The regional plan s objectives can include physical, environmental, social, and political needs. The larger spatial and temporal frameworks of regional sediment management, as well as the range of disciplines required in most regional planning, result in numerous stakeholders with varied interests.

Regional Sediment Management (RSM) refers to the effective utilization of littoral, estuarine, and riverine sediment resources in an environmentally effective and economical manner. RSM strives to maintain or enhance the natural exchange of sediment within the boundaries of the physical system. A region may include a variety of geologic features, uplands, beaches, inlets, rivers, estuaries, and bays. Implementation of RSM recognizes that the physical system and embedded ecosystems are modified and respond beyond the formal dimensions and time frames of individual projects. The larger spatial and longer temporal perspectives of RSM, as well as the broad range of disciplines with a stake in RSM projects, result in partnerships and co-leadership of RSM initiatives by the stakeholders. This paper discusses ongoing demonstrations of RSM by the U.S. Army Corps of Engineers (USACE). Six USACE District offices are implementing RSM demonstration projects, and two Districts within the State of Florida have developed their RSM plans with consensus and partnership with the State of Florida's Department of Environmental Protection (FDEP), Office of Beaches and Coastal Systems (OBCS). The paper concludes by highlighting numerical models that have been applied at the USACE District, New York for RSM, and Research and Development (R&D) being conducted and planned at the Coastal and Hydraulics Laboratory (CHL) in support of RSM., Presented at the 14th Annual National Conference on Beach Preservation Technology, Orlando, Florida. The original document contains color images.

Invisible lines of satellite information are rapidly supplementing the sea lanes, roads, and cables of today and yesterday. Television, voice, weather, images, location, and other data stream down to Earth from satellites orbiting above -- all of which are operated by military, civil, or commercial entities. These satellites perform functions similar to those of terrestrial public utilities, providing needed goods and services. Unlike their earthbound counterparts, which service only a neighbor hood or city, these utilities are used on almost every continent by billions of people and may thus be appropriately labeled "global utilities." They are critically important to the national security, economies, and safety of the user nations. Over the past years, the reliance on satellites for all types of global utilities has increased, and future loss of any of these satellites, whether through operator error or subversion, would have drastic implications. Satellite services are invaluable to the United States and its allies. The use of space is one of this country's greatest strengths, but extensive reliance on global utilities also represents a substantial liability. Currently no physical system exists for protecting these global utilities. We can bring to bear economic, political, and other multilateral pressures on an offending nation or group, and we are party to treaties and agreements that prohibit certain activities -- these have worked well in the past. But what if the threat comes from nongovernment organizations, terrorist groups, or an adversarial nation? Or what if we are unable to identify the sources of the offense? Treaties and sanctions may not prove so effective. The argument presented here is that protecting global utilities is a natural extension of the Air Force mission to protect other high-value airborne assets; it is also an extension of the Department of Defense's protection of all friendly assets., Published in the Aerospace Power Journal, v14 n2 p37-41, Summer 2000.