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PubMed1995

Type-specific stabilization and target-dependent survival of regenerating ganglion cells in the retina of adult rats.

Axotomy-induced degradation of retinal ganglion cells (RGC) can be delayed if the destructive features of activated microglial cells are pharmacologically neutralized, and prevented if the axons are permitted to regrow into transplanted autologous peripheral nerve (PN) pieces. This study was undertaken to classify the regenerating rat RGC and to examine target-dependent effects on survival of subsets of neurons. In analogy to the normal rat retina, we have categorized the retrogradely labeled, regenerating RGC into five classes which are morphologically distinct and reminiscent of normal RGC correlates (types I, II, III, delta-cells, and displaced RGC). Six weeks after transplantation of peripheral nerve to the transected optic nerve, large, type I-like cells (RI) constituted 5.7 +/- 2.0% of the total population. Smaller, round to oval cells of type RII represented the majority of labeled neurons (64.5 +/- 6.1%). Cells of type RIII constituted 4.6 +/- 1.7% of the total population and had very typical, middlesized, polarized perikarya and large dendrites. Less frequent (< 1%) were R-delta and displaced RGC. Transplantation of a PN graft which was not reconnected with a central target (blind-ending group) and monitoring of the extant neurons showed a progressive disappearance of the regenerating RGC, such that 6 months after surgery predominantly few large cells survived. When the retinas were treated with macrophage/microglia-inhibiting factor (MIF), and the regenerating axons were guided into the pretectum, predominantly large RGC of type RI survived. Guidance of the axons into their major natural target, the superior colliculus (SC), resulted in selective survival of many small, RII-like RGC. Calculation of the dendritic coverage factors for the major types of RGC revealed that dendrites of the most abundant small cells of type RII overlapped uniformly and covered the retinal surface completely, whereas cells of types RI and RIII did not suffice for surface coverage. The results suggest that combined suppression of axotomy-induced microglial activation and guidance of regenerating axons with a PN graft into central targets is a suitable technique to produce sufficient numbers of regenerating axons which may retrieve some functional properties. Target-specific neuronal contacts are likely involved in morphological stabilization and better survival of regenerating neurons.

Animals↗
PubMed1994

Rapid activation of post-hepatectomy factor/nuclear factor kappa B in hepatocytes, a primary response in the regenerating liver.

The liver represents one of the few organs in the intact animal that has the capacity to regenerate following injury or partial hepatectomy. One of the earliest responses that has been detected in the remnant liver is the activation of post-hepatectomy factor(s) (PHF), a kappa B site DNA binding activity. We reasoned that understanding the molecular nature of PHF might provide insight into what triggers liver regeneration. We found that PHF is rapidly activated and turned over in the regenerating liver, demonstrating peak activity at 30 min post-hepatectomy and virtual disappearance by 1 h. As determined by supershift, cross-linking, and cross-linking/immunoprecipitation analyses, PHF contains intact p50/p65nuclear factor kappa B (NF-kappa B) subunits. To explore the basis for activation of PHF/NF-kappa B in the regenerating liver, we determined the level of individual Rel family subunits in the nuclei of normal and regenerating liver cells. We found evidence for nuclear translocation of p65/RelA, but other Rel family proteins including p50/NF-kappa B1 and p52/NF-kappa B2 are present at a low level in the nuclei of cells at a constitutive level pre- and post-hepatectomy and appear not to form DNA binding homodimers. The level of I kappa B-alpha falls slightly then increases at 3 h post-hepatectomy in concert with the induction of its mRNA. As demonstrated by the induction of I kappa B-alpha mRNA in hepatocytes in situ and identification of PHF/NF-kappa B in cultured hepatocytes, PHF/NF-kappa B is localized primarily in hepatocytes in the regenerating liver. This represents one of the few examples of NF-kappa B activation in the intact animal in a non-hematopoietic cell type. The activation of PHF/NF-kappa B suggests a mechanism by which hepatocytes regulate their mitogenic program during liver regeneration.

Animals↗
PubMed1993

Stage-dependent effects of retinoic acid on the regenerating limbs of larval Korean salamander, Hynobius leechii, at two amputation levels.

The morphological and biochemical data obtained in this series of experiments clearly confirm the previous finding about the relationship between the stage of limb regeneration and the effects of RA on duplication, i.e., the most sensitive stage for RA-induced duplication is the stage of dedifferentiation, regardless of the level of amputation. However, when the RA effects were expressed as a function of time after amputation, the upper arm regenerates clearly showed a prolonged and delayed response to RA treatment compared to the lower arm regenerates. These findings were further supported by the data on acid phosphatase activity, which may reflect the level of dedifferentiation. Furthermore, the slow increase of this enzyme activity above the control level until 8 days after RA-injection corresponds to the late appearance of limb regenerates after RA treatment. At present, we do not have any clear explanation why upper arm regenerates and lower arm regenerates show differences in the MLP's and different temporal profiles for the RA-evoked limb pattern duplications. However, the difference in the level of dedifferentiation after simple amputation and after RA-treatment suggests that RA-induced changes in the positional identity of blastema cells may require a prolonged and augmented state of dedifferentiation. In this scheme, the level and type of CRABP may play a critical role as suggested in the case of regenerating axolotl limbs (McCormick et al., 1988).

Acid Phosphatase↗
PubMed1993

Transforming growth factor beta gene expression is transiently enhanced at a critical stage during liver regeneration after CCl4 treatment.

BACKGROUND: Transforming growth factor beta 1 (TGF beta 1) gene expression is increased in CCl4-injured rat livers. The biologic link of this increase and liver regeneration has not been established. EXPERIMENTAL DESIGN: To explore the identity of the TGF beta 1-producing cells in the CCl4 regenerating liver, we hybridized untreated and CCl4-treated liver sections of TGF beta 1-specific riboprobes and immunolocalized TGF beta 1 protein, simultaneously. To assess the dynamics of cellular proliferation during hepatic regeneration, chronologic changes in the cellular DNA synthesis were also monitored by [3H]thymidine incorporation and autoradiography. In situ hybridization analyses were further extended by subfractionation of nonparenchymal cells into Kupffer cells/macrophages, endothelial and Ito cells, and determining TGF beta 1 mRNA levels in different cell types. Finally, we experimentally tested if the temporal relationship between the transient elevation of expression of TGF beta 1 and hepatic cell proliferation were casually related. RESULTS: We observed that the rate of DNA synthesis was the highest around 36 hours post-treatment and preceded the time of enhanced accumulation of TGF beta 1 transcripts and protein, both of which peaked at approximately 48 hours and declined thereafter. Transient upregulation of TGF beta 1 gene expression was seen in the inflammatory cell infiltrates around the central vein and at less extent, in portal tracts, and in perisinusoidal cells near the zone of necrosis. Like TGF beta 1 transcripts, TGF beta 1 protein was also predominantly co-localized in and around the pericentral and periportal cells. Kupffer cells, that accumulate abundantly in the liver 48 hours after CCl4 administration, were the primary producers of TGF beta 1. The injection of neutralizing anti-TGF beta 1 antibodies into animals prevented both the decline in [3H]thymidine incorporation and cell division in the waning phases of hepatic regeneration at 72 hours. CONCLUSIONS: Based on our observations that (i) TGF beta 1 gene expression is triggered transiently during a crucial phase of liver regeneration, (ii) the exogenously added TGF beta 1 inhibits hepatic DNA synthesis and that (iii) the administration of TGF beta 1 antibodies extends the proliferative response of the regenerating liver, we conclude that TGF beta 1 plays a pivotal role in down regulating liver regeneration.

Animals↗
PubMed1995

Medullary and gangliar regeneration after unilateral removal of a segment of spinal cord of the trunk and corresponding ganglion in adult newts.

Regeneration of the spinal cord, segmental nerves and sensory ganglia takes place after tail amputation in the newt. Many histological and immunocytochemical observations provide evidence that the ependymal tube is the source not only of new neurons and glial cells in the spinal cord, but also of some cells that go on to participate in the formation of the spinal ganglia of the regenerating tail. In previous experiments involving the removal of the spinal ganglia of the trunk, no regeneration was observed and it is thought that the trunk region differs from the tail region with regard to the ability to regenerate sensory ganglia. However, in these experiments the spinal cord of the trunk was not damaged. In the present work involving adult newts (Triturus carnifex Laur.), unilateral ablation of a segment of the spinal cord of the trunk in addition to removal of a corresponding spinal ganglion was performed. In these experimental conditions, regeneration of a rudimentary spinal ganglion near the regenerated side of the spinal cord segment was observed in several cases. Histological observations carried out 2, 4, 6 and 13 months after the operation support the view that some cells migrating from the lateroventral part of the regenerating side of the spinal cord via the developing ventral root could participate in the formation of the rudimentary spinal ganglion.

Amputation, Surgical↗
PubMed1995

Successful regeneration of mandibular Class II furcation defects: an evidence-based treatment approach.

The purpose of the present evidence-based critical review was to define goals and outcomes for regenerative therapy of Class II furcation defects and rank the efficacy of current regenerative procedures based on the available literature. Meta-analysis was employed to quantitate the mean overall expected changes and compare various techniques. The evidence presented in the literature was used to determine factors affecting regeneration of Class II furcation defects. These factors were used to establish decision-making trees to enhance success and highlight potential shortcomings of the technique. Guided tissue regeneration, used alone or in combination with bone replacement grafts, had the highest overall ranking. Mean reduction in probing depths and gains in vertical and horizontal attachment levels were all statistically significant at 6 months. Similar results were obtained in the 12-month studies. Compared to flap debridement, guided tissue regeneration resulted in greater reduction in probing depths and greater gains in vertical and horizontal attachment levels. Guided tissue regeneration provided almost identical results whether used with or without root conditioning, suggesting that root conditioning does not offer an adjunctive effect. A combination of guided tissue regeneration and bone replacement grafts yielded better results than did guided tissue regeneration alone in reducing probing depths and increasing vertical attachment levels. The decision-making trees derived from analysis of these results may assist the clinician in improving success and predictability of guided tissue regeneration procedures in Class II furcation defects.

Bibliographies as Topic↗
PubMed1996

Re-examining jaw regeneration in urodeles: what have we learnt?

Urodele amphibians can regenerate not only their limbs and tails, but also their upper and lower jaws rather faithfully. However, relatively few studies of jaw regeneration in amphibians have been carried out, especially in recent years. It is therefore important to reexamine thoroughly this regenerating system, since the advent of sophisticated morphological techniques and the development of molecular approaches offer the promise of renewed and rapid progress in our understanding of complex developmental problems such as this. This paper briefly reviews some of the early research on jaw regeneration, some of the fundamental questions which have been asked and have yet to be answered, and the work we have carried out in order to understand the molecular mechanisms underlying jaw regeneration in the newt, Notophthalmus viridescens. In addition, some aspects of jaw regeneration will be discussed in relation to regeneration of the adult limb.

Animals↗
PubMed1996

The influence of predegenerated nerve grafts on axonal regeneration from prelesioned peripheral nerves.

Recent in vitro work has indicated that predegenerated segments of peripheral nerve are more capable of supporting neurite growth from adult neurons than fresh segments of nerve, whereas previous in vivo studies which investigated whether predegenerated nerve segments used as grafts are capable of enhancing axonal regeneration produced conflicting results. We have reinvestigated this question by using predegenerated nerve grafts in combination with conditioning lesions of the host nerve to determine the optimal conditions for obtaining the maximal degree of regeneration of myelinated axons. The sciatic nerve of adult Dark Agouti rats were sectioned at midthigh level, and the distal portion was allowed to predegenerate for 0, 6 or 12 d in situ. 10-15 mm lengths of these distal nerve segments were then syngenically grafted onto the central stumps of sciatic nerves which had themselves received a conditioning lesion 0, 6, and 12 d previously, making a total of 9 different donor-host combinations. The grafts were assessed histologically 3 or 8 wk after grafting. Axonal regeneration in the 9 different donor-host combinations was determined by counting the numbers of myelinated axons in transverse sections through the grafts. All grafts examined contained regenerating myelinated axons. The rats given a 3 wk postgrafting survival period had an average of between 1400 and 5300 such axons. The rats given an 8 wk postgrafting survival period had between about 13,000 and 25,000 regenerating myelinated axons. Analysis of variance revealed significant main effects for both the Donor and Host conditions as well as Weeks (i.e. survival period after grafting). These results indicate that both a conditioning lesion of the host neurons and the degree of predegeneration of peripheral nerve segments to be used as grafts are of importance in influencing the degree of axonal regeneration. Of these 2 factors the conditioning lesion of the host appears to have the greater effect on the final number of regenerating myelinated axons.

Animals↗
PubMed1997

Plant regeneration of indica rice (Oryza sativa) cultivars from mature embryo-derived calli.

Plant regeneration from seven-week-old callus cultures derived from mature embryos of several indica rice cultivars was achieved with frequencies of morphogenic calli from 10 to 47%. Three media were tested both for callogenesis and plant regeneration. For 3 of the 7 genotypes examined, the best combination of media for plant regeneration was Murashige & Skoog basal medium: MSC (callogenesis) and MSR (regeneration). The rates of callogenesis were not related to the capacity for plant regeneration. Two genotypes CR-1113 and CR-5272 produced the highest number of regenerated green plants. The results of this study suggest that genetic differences could be directly linked to the ability to regenerate in these plant cultivars.

Culture Techniques↗
PubMed1998

Subcellular localization of phosphoprotein B-50 in regenerating muscle. An immuno-electron microscopic study.

Phosphoprotein B-50, also termed growth-associated protein GAP43, is a membrane-bound phosphoprotein expressed in neurons. It is particularly abundant during periods of axonal outgrowth in development and regeneration of the central and peripheral nervous systems. Recently the expression of phosphoprotein B-50 in regenerating muscle fibers was reported and it was assumed that phosphoprotein B-50, in muscles, plays a role in the determination of the growth morphology of regenerating muscle fibers. Thus, phosphoprotein B-50 no longer can be regarded as a neuron-specific molecule. In this paper we study the subcellular localization of phosphoprotein B-50 in regenerating human skeletal muscle fibers by electron immunohistochemistry. Phosphoprotein B-50 immunoreactivity is randomly distributed over the nuclear and perinuclear area of regenerating muscle fibers. Previously, by light-microscopy phosphoprotein B-50 immunoreactivity was demonstrated on the inner face of the sarcolemma in hypotrophic type 1 fibers in congenital fiber type disproportion. It is this distribution of phosphoprotein B-50 in developmentally disordered myocytes in particular which allows an analogy to the corresponding results found for growing axons. But we did not find subsarcolemmal expression of B-50 in regenerating muscle fibers. Probably this indicates that there is a difference in B-50 expression between regeneration of muscle fibers and developmentally retarded/immature myofibers. The presented data suggest that phosphoprotein B-50 is inserted only stage-dependent in the extending sarcolemma of the growing muscle fiber. Analogously to the nervous system, phosphoprotein B-50 may serve a local function involving transmembrane signalling by means of calmodulin binding of phosphoprotein B-50 and/or phosphoprotein B-50 phosphorylation and dephosphorylation.

GAP-43 Protein↗
PubMed1998

Capability of neurite regeneration of retinal explant from adult rat after optic nerve injury.

Axons of the central nervous system in adult mammals do not regenerate spontaneously after axotomy. To understand whether the optic nerve of adult mammals loses the intrinsic capability to regenerate after injury, we have studied the capability of neurite regeneration of retinal explant from adult rat after optic nerve axotomy in vitro. After experimental blunt damage to the optic nerve of adult Wistar rat, the retinal explants from three days, one week, two weeks and three weeks after axotomy were put in tissue culture to observe the neurite growth after four days' incubation. The neurites were identified as retinal neuron origin by immunocytochemical staining using monoclonal antibody to neurofilament. The results demonstrate that retinal explants from adult rat after optic nerve damage have the capability of neurite regeneration; the capability is strongest in the group of one week after axotomy of optic nerve, but it decreases with passage of the time. On the other hand, the retinal explant from the control group of uninjured eye does not regenerate neurite in tissue culture. These results indicate that the retinal explant of adult rat has intrinsic capability to regenerate after optic nerve injury in vitro, and the capability of neurite regeneration decreases after one week post-trauma.

Animals↗
PubMed1998

Signal transduction during liver regeneration.

Following partial hepatectomy (PH), there is a rapid and highly orchestrated series of biochemical events which occur prior to cellular proliferation. Some of these events are presumably intimately linked with the eventual regeneration of the liver, whereas others are likely to be stress related or required for the continued differentiated function of the liver while regeneration is occurring. The regulation of the AP-1 transcription factor c-Jun during hepatic regeneration has been studied here. There is a progressive increase in c-Jun-mRNA levels after sham operation, one-third PH, and two-thirds PH. A concomitant increase in activating protein 1 (AP-1) binding activity is also observed. The c-Jun protein is a major constituent of the AP-1 complex in quiescent and early regenerating liver. The activity of c-Jun amino-terminal kinase (JNK), which phosphorylates the activation domain of the c-Jun protein, is markedly stimulated after one-third and two-thirds PH. c-Jun amino-terminal kinase-1 is a constituent of this stimulated JNK activity after PH. When primary cultures of adult rat hepatocytes are incubated with epidermal growth factor or transforming growth factor-alpha, AP-1 transcriptional activity is increased and the activation domain of the c-Jun protein is further potentiated. Phosphopeptide mapping of the endogenous c-Jun protein in proliferating cultured hepatocytes demonstrates phosphorylation of the c-Jun activation domain. Pretreatment of animals prior to PH with a neutralizing antibody to tumour necrosis factor-alpha (TNFalpha), inhibits hepatocyte DNA synthesis and JNK activation. It is concluded that the stimulation of one-third or two-thirds PH activates JNK through a mechanism that requires TNFalpha, which phosphorylates the c-Jun activation domain in hepatocytes, resulting in enhanced transcription of AP-1-dependent genes. Although nuclear factor-kappa B (NFkappaB) binding activity is induced during liver regeneration following PH, the physiological consequence of this induction is unknown. The role of NFkappaB during liver regeneration has been assessed by delivering to the liver a super-repressor of NFkappaB activity using an adenoviral vector expressing a mutated form of IkappaB. This adenovirus (Ad5IkappaB) was almost exclusively expressed in the liver and inhibited NFkappaB DNA binding activity and transcriptional activity in cultured cells as well as in the liver in vivo. Following PH, Ad5IkappaB, but not a control adenovirus (Ad5betagal), resulted in the induction of apoptosis as demonstrated by histological staining and TUNEL analysis. In addition, infection with Ad5IkappaB but not Ad5betagal decreased the mitotic index following PH. These two phenomena, increased apoptosis and cell cycle arrest, were associated with liver failure in animals infected with the ad5IkappaB but not Ad5betagal as demonstrated by elevated serum bilirubin and ammonia levels. Thus, the induction of NFkappaB during liver regeneration following PH appears to be a required event to prevent apoptosis and to allow for normal cell cycle progression.

Animals↗
PubMed1994

Periodontal repair in dogs: space provision by reinforced ePTFE membranes enhances bone and cementum regeneration in large supraalveolar defects.

Regeneration of alveolar bone and cementum following reconstructive therapy with reinforced space providing expanded polytetrafluorethylene (ePTFE) membranes was evaluated in supraalveolar mandibular premolar periodontal defects in five beagle dogs. The surgically-created defects in contralateral jaw quadrants were randomly assigned to receive the dome-shaped membrane or serve as surgical control. Flaps were positioned to completely submerge the teeth and sutured. The dogs were sacrificed 8 weeks after surgery and tissue blocks including teeth and surrounding structures processed for histology. Membrane treated defects in two animals became exposed and infected leaving intact quadrants in three dogs for histometric analysis. Parameters evaluated included defect height, height and area of regenerated alveolar bone, height of regenerated cementum, root resorption, and ankylosis. Mean defect height approximated 4.1 mm. Mean height (+/- s.d.) of regenerated alveolar bone amounted to 2.9 +/- 0.6 and 0.6 +/- 0.2 mm for membrane and control defects, respectively (P = 0.006). Corresponding values for bone area were 1.4 +/- 0.7 and 0.4 +/- 0.4 mm2 (P = 0.02). Cementum regeneration was observed in all teeth averaging (+/- s.d.) 1.6 +/- 0.3 mm for membrane treated and 0.1 +/- 0.1 mm for control defects (P = 0.01). Small amounts of root resorption were seen in all teeth with no significant difference between treatments. Ankylosis was noticed in three membrane treated and two control teeth. The present study provides a biologic rationale for space provision for enhanced bone and cementum regeneration in periodontal defects subject to reconstructive therapy.

Alveolar Bone Loss↗
PubMed2003

Periodontal regeneration in humans using recombinant human platelet-derived growth factor-BB (rhPDGF-BB) and allogenic bone.

BACKGROUND: Purified recombinant human platelet-derived growth factor BB (rhPDGF-BB) is a potent wound healing growth factor and stimulator of the proliferation and recruitment of both periodontal ligament (PDL) and bone cells. The hypothesis tested in this study was that application of rhPDGF-BB incorporated in bone allograft would induce regeneration of a complete new attachment apparatus, including bone, periodontal ligament, and cementum in human interproximal intrabony defects and molar Class II furcation lesions. METHODS: Nine adult patients (15 sites) with advanced periodontitis exhibiting at least one tooth requiring extraction due to an extensive interproximal intrabony and/or molar Class II furcation defect were entered into the study. Eleven defects were randomly selected to receive rhPDGF-BB. Following full-thickness flap reflection and initial debridement, the tooth roots were notched at the apical extent of the calculus, the osseous defects were thoroughly debrided, and the tooth root(s) were planed/prepared. The osseous defects were then filled with demineralized freeze-dried bone allograft (DFDBA) saturated with one of three concentrations of rhPDGF-BB (0.5 mg/ml, 1.0 mg/ml, or 5.0 mg/ml). Concurrently, four interproximal defects were treated with a well accepted commercially available graft (anorganic bovine bone in collagen, ABB-C) and a bilayer collagen membrane. Radiographs, clinical probing depths, and attachment levels were obtained preoperatively (at baseline) and 9 months later. At 9 months postoperatively, the study tooth and surrounding tissues were removed en bloc. Clinical and radiographic data were analyzed for change from baseline by defect type and PDGF concentration. The histologic specimens were analyzed for the presence of regeneration of a complete new attachment apparatus coronal to the reference notch. RESULTS: The post-surgical wound rapidly healed and was characterized by firm, pink gingivae within 7 to 10 days of surgery. There were no unfavorable tissue reactions or other safety concerns associated with the treatments throughout the course of the study. In rhPDGF/allograft sites, the vertical probing depth (vPD) reduction for interproximal defects was 6.42 +/- 1.69 mm (mean +/- SD) and clinical attachment level (CAL) gain was 6.17 +/- 1.94 mm (both P < 0.01). Radiographic fill was 2.14 +/- 0.85 mm. Sites filled with ABB-C had a PD reduction and CAL gain of 5.75 +/- 0.5 and 5.25 +/- 1.71, respectively. Furcation defects treated with rhPDGF/allograft exhibited a mean horizontal and vertical PD reduction of 3.40 +/- 0.55 mm (P < 0.001) and 4.00 +/- 1.58 mm (P < 0.005), respectively. The CAL gain for furcation defects was 3.2 +/- 2.17 mm (P < 0.030). Histologic evaluation revealed regeneration of a complete periodontal attachment apparatus, including new cementum, PDL, and bone coronal to the root notch in four of the six interproximal defects and all evaluable (four of four) furcation defects treated with PDGF. Two of the four interproximal intrabony defects treated with ABB-C and membrane exhibited regeneration. CONCLUSIONS: Use of purified rhPDGF-BB mixed with bone allograft results in robust periodontal regeneration in both Class II furcations and interproximal intrabony defects. This is the first report of periodontal regeneration demonstrated histologically in human Class II furcation defects.

Adult↗
PubMed2005

Wound keratins in the regenerating epidermis of lizard suggest that the wound reaction is similar in the tail and limb.

The keratin cytoskeleton of the wound epidermis of lizard limb (which does not regenerate) and tail (which regenerates) hase been studied by qualitative ultrastructural, immunocytochemical, and immunoblotting methods. The process of re-epithelialization is much shorter in the tail than in the limb. In the latter, a massive tissue destruction of bones, and the shrinkage of the old skin over the stump surface, delay wound closure, maintain inflammation, reduce blastemal cell population, resulting in inhibition of regeneration. The expression of special wound keratins found in the newt epidermis (W6) or mammalian epidermis (K6, K16, and K17) is present in the epidermis of both tail and limb of the lizard. These keratins are not immunolocalized in the migrating epithelium or normal (resting) epidermis but only after it has formed the thick wound epithelium, made of lacunar cells. The latter are proliferating keratinocytes produced during the cyclical renewal or regeneration of lizard epidermis. W6-immunolabeled proteic bands mainly at 45-47 kDa are detected by immunoblotting in normal, regenerating, and scarring epidermis of the tail and limb. Immunolabeled proteic bands at 52, 62-67 kDa (with K6), at 44-47, 60, 65 kDa (with K16), and at 44-47 kDa (with K17) were detected in normal and regenerating epidermis. It is suggested that: (1) these keratins constitute normal epidermis, especially where the lacunar layer is still differentiating; (2) the wound epidermis is similar in the limb and tail in terms of morphology and keratin content; (3) the W6 antigen is similar to that of the newt, and is associated with tonofilaments; (4) lizard K6 and K17 have molecular weights similar to mammalian keratins; (5) K16 shows some isoforms or degradative products with different molecular weight from those of mammals; (6) K17 increases in wound keratinocytes and localizes over sparse filaments or small bundles of short filaments, not over tonofilaments joined to desmosomes; and (7) failure of limb regeneration in lizards may not depend on the wound reaction of keratinocytes.

Amputation Stumps↗
PubMed1997

Influence of Surface Oxides on Ethanol Regeneration of Spent Carbonaceous Adsorbents

Activated carbon (AC) and activated carbon fiber (ACF) that adsorbed aromatic compounds were regenerated by ethanol. The influence of their acidic surface oxides on ethanol regeneration was studied based on the frontier orbital theory. It is found that the regeneration efficiency can be correlated by the energy difference between HOMO of aromatic compounds and LUMO of adsorbents |EH - EL|. The regeneration efficiency is improved by oxidizing AC or ACF because the adsorptive interaction becomes weak as the energy difference |EH - EL| increases. The influence of the oxides on repeating ethanol regeneration of the carbons that adsorbed p-cresol was then experimentally elucidated. Although the regeneration efficiency of oxidized AC or ACF is kept higher than that of original AC or ACF even after the 16th regeneration, the oxidation has no practical use because the adsorption capacity is decreased by the oxidation. Copyright 1997 Academic Press. Copyright 1997Academic Press

Journal Article↗
PubMed1991

Experimental serotonin myopathy as an animal model of muscle degeneration and regeneration in muscular dystrophy.

Degenerating and regenerating muscle fibers, in serotonin-induced myopathy (SM) of rats, were investigated histochemically, immunohistochemically and electron microscopically with polyclonal antibodies against dystrophin, type IV collagen and laminin. The myopathy produced was characterized by grouping of degenerating and regenerating muscle fibers, and degeneration of capillary endothelial cells. Dystrophin disappeared in an early stage of muscle degeneration and reappeared in an early stage of regeneration. On the other hand, type IV collagen and laminin were well preserved throughout the degeneration and regeneration processes, even on the shrunk and wrinkled basement membrane of empty muscle fibers after phagocytosis. Muscle fiber regeneration was completed within each tube of the preserved basement membrane through the fusion of myoblasts derived from satellite cells of single necrotic fibers, myotubes already being visible on the 1st or 2nd day of regeneration on light microscopy. These small regenerating myotubes did not fuse with each other at all. The findings in the present experimental SM study are compatible with those in Duchenne muscular dystrophy, especially at the preclinical stage.

Animals↗
PubMed1988

Regeneration of the cell wall in protoplasts of Candida albicans. A cytochemical study using wheat germ agglutinin and concanavalin A.

To assess the dynamics of synthesis of the wall by regenerating Candida albicans protoplasts deposition of chitin and mannoproteins were investigated ultrastructurally using wheat germ agglutinin conjugated with either horseradish peroxidase or colloidal gold, and Concanavalin A coupled to ferritin respectively. Freshly prepared protoplasts lacked wheat germ agglutinin receptor sites but after 1-2 h of regeneration, they were detected. After 4-5 h of regeneration, the cell wall showed a discrete structure which was only labelled with wheat germ agglutinin in thin sections. At this stage of regeneration the outermost layer of the wall was labelled with clusters of Concanavalin A-ferritin particles. After 8 h regeneration, the cell wall appeared compact, and homogenously marked with wheat germ agglutinin whereas only the surface layers appeared consistently labelled with Concanavalin A-ferritin. From these observations we conclude that C. albicans protoplasts are able to regenerate in liquid medium a cell wall consisting of a network of chitin fibrils and mannoproteins at least (glucan polymers were not determined in the present cytological study). The former are the fundamental component of the inner layers at early stages of regeneration, whereas the latter molecules are predominant in the outer layers of the wall.

Candida albicans↗