Early Phase Of Regeneration Research Articles

Elf Electromagnetic Fields Affect Gene Expression of Hegenerating Rat Liver Following Partial Hepatectomy

Pulsed extremely-low-frequency magnetic fields (ELF-PEMFs) influence the expression of oncogenes c-myc and c-ras and of ornithine decarboxylase (ODC) in the regenerating rat liver following partial hepatectomy. In fact, while the mRNA's encoding both oncogenes are present in very low amounts in the normal liver, their concentration is dramatically increased during regeneration. Ornithine decarboxylase and c-myc mRNA's reach a maximum during the early phases of regeneration (3 hours after surgery) and decrease thereafter. c-ras mRNA reaches a maximum 40 hours after the operation. Treatment with ELF-PEMFs delivered to the animals immediately after the operation and every 12 hours thereafter increases The concentration of both oncogenes and of ornithine decarboxylase mRNA' s at 3 hours (c-myc and ODC) and at 40 hours (c-ras) respective-ty.

Sequential changes in alanine metabolism following partial hepatectomy in the rat

After partial hepatectomy, the liver undergoes an array of metabolic changes until regeneration is complete. Since carbons derived from alanine can be incorporated into most metabolic pools, we studied the metabolism of 14C-labeled alanine during the early phase of regeneration. Sham operated (controls) and partially hepatectomized rats weighing about 200 g each were injected intraperitoneally with 1-[U- 14C]alanine at 9, 18, and 36 hours after surgery. The animals were killed 2 hours after injection. Compared to the controls, alanine oxidation was markedly depressed ( P < 0.05) in the 9- and 18-hour groups, but was restored in the 36-hour group. The specific activity of plasma glucose and hepatic glycogen was elevated 9 and 18 hours after partial hepatectomy. There was a corresponding increase in the activities of fructose-1,6-diphosphatase and phosphoenolpyruvate carboxykinase. Hepatic protein specific activity increased by 30, 74, and 120%, respectively 9, 18, and 36 hours after partial hepatectomy. Hepatic fatty acids followed a similar pattern. In a separate set of experiments, the distribution of radioactivity in glutamic acid was measured. The results showed that alanine carbons enter the citric acid cycle primarily via the acetyl CoA pathway in the controls, but via the oxaloacetate pathway in partially hepatectomized rats. The results demonstrate significant changes in the activities of metabolic pathways of alanine in the early phase of hepatic regeneration.

Expression of myosin isoforms during notexin-induced regeneration of rat soleus muscles

Myosin isozymes and their fiber distribution were studied during regeneration of the soleus muscle of young adult (4–6 week old) rats. Muscle degeneration and regeneration were induced by a single subcutaneous injection of a snake toxin, notexin. If reinnervation of the regenerating muscle was allowed to occur (functional innervation nearly complete by 7 days), then fiber diameters continued to increase and by 28 days after toxin treatment they attained the same values as fibers in the contralateral soleus. If the muscles were denervated at the time of toxin injection, the early phases of regeneration still took place but the fibers failed to continue to increase in size. Electrophoresis of native myosin showed multiple bands between 3 and 21 days of regeneration which could be interpreted as indicating the presence of embryonic, neonatal, fast and slow myosins in the innervated muscles. Adult slow myosin became the exclusive form in innervated regenerates. In contrast, adult fast myosin became the predominant form in denervated regenerating muscles. Immunocytochemical localization of myosin isozymes demonstrated that in innervated muscles the slow form began to appear in a heterogeneous fashion at about 7 days, and became the major form in all fibers by 21–28 days. Thus, the regenerated muscle was almost entirely composed of slow fibers, in clear contrast to the contralateral muscle which was still substantially mixed. In denervated regenerating muscles, slow myosin was not detected biochemically or immunocytochemically whereas fast myosin was detected in all denervated fibers by 21–28 days. The regenerating soleus muscle therefore is clearly different from the developing soleus muscle in that the former is composed of a uniform fiber population with respect to myosin transitions. Moreover the satellite cells which account for the regeneration process in the soleus muscle do not appear to be predetermined with respect to myosin heavy chain expression, since the fibers they form can express either slow or fast isoforms. The induction of the slow myosin phenotype is entirely dependent on a positive, extrinsic influence of the nerve.

Analysis of axonal regeneration through the silicone regeneration chamber: A retrograde tracing study in the rabbit facial nerve

Transected facial nerve buccal branches in the adult rabbit were sutured to a silicone growth chamber and regeneration was observed at 3, 5, and 7 weeks postoperation. Using the retrograde axonal transport of horseradish peroxidase technique the soma in the facial motor nucleus were counted and the number was correlated with the number of axons found in the mid-cross section of the regenerating buccal branch and with the number of axons in the original nerve. The somatotopic reorganization in the facial motor nucleus was examined. The mean number of facial motoneuron soma labeled with HRP in the control was 68.0% (±18.6, SE) of the axons counted at periphery. In the regenerating nerves, the labeled soma represented 2.4% of the preoperative controls after 3 weeks and rose to 8.6 and 43.9% at 5 and 7 weeks, respectively. At 3 weeks post-operative time, four of six regenerating nerves did not contain any myelinated axons at the center cross section. The ratios of labeled soma to the regenerating myelinated axons counted at the center cross section at 5- and 7-week time points were 42.2 and 61.1%, respectively. The location of the soma found in the early regeneration phase was similar to the normal distribution except in the dorsal subnucleus. After 7 weeks the proportion of labeled soma in the intermediate subnucleus declined but the general pattern replicated the distribution found in normal control preparations.

The effect of E. coli infection on the prostaglandin synthesizing capacity of postobstructive rat kidney.

The PGE2, PGI2, PGF2 alpha and TxA2 synthesizing activities were studied in an isolated microsomal fraction of rat kidney after temporary, unilateral ureter obstruction and E. coli infection. In the early phase of regeneration the synthesis of vasodilatory PGI2 was increased, whereas that of vasoconstrictory PGF2 alpha was decreased. An increased PGE2 synthesizing activity was observed when renal obstruction was associated with infection. The role of these changes in regenerating the haemodynamics and function of postobstructive kidney is discussed.

-Glucan Synthesis and Glucan Synthase Activities during Early Stages of Cell Wall Regeneration by Protoplasts from Saprolegnia monoica

Protoplasts isolated from Saprolegnia monoica were used to study β-glucan synthases and polysaccharide synthesis during wall regeneration. (1→4)-β- and (1→3)-β-glucan synthase activities of plasma membranes and internal membranes increased during regeneration. Within minutes of cultivation, protoplasts transferred radioactivity from [14C]glucose to cellulose and other cell wall polymers. UDP[14C]glucose did not serve as substrate. Cellulose microfibrils were produced from the beginning of regeneration. The early phases of regeneration are realized by plasma membrane enzymes having remained intact during protoplast isolation and independently of the Golgi apparatus.

Regenerative capability of skeletal muscle in chicken muscular dystrophy.

To examine the morphological sequence of regenerating fibers after myonecrosis in dystrophic muscles, 0.5 ml of 0.5% bupivacaine hydrochloride (BPVC) (Marcaine) solution, a local anesthetic with a cytotoxic effect on the muscle fibers, was injected directly into the dystrophic (line 413) and nondystrophic (line 412) posterior latissimus dorsi (PLD) muscles of young and adult chickens. Although the dystrophic muscles after BPVC injection showed a rapid recovery with a similar tempo to that of nondystrophic ones, they showed different morphological behavior in the early phase of regeneration, including marked variability in the size of fibers and in the intracytoplasmic enzyme activities of nicotinamide adenine dinucleotide, reduced-tetrazolium reductase (NADH-TR), acetylcholinesterase (AChE), and nonspecific esterase (NSE).

Branching of regenerating retinal axons and preferential selection of appropriate branches for specific neuronal connection in the newt

Exact trajectory and pattern of branching of individual regenerating retinal axons derived from different retinal quadrants was detected within the tectum by labeling selected retinal axons with horseradish peroxidase (HRP) at the 4th, 6th, and 10th weeks after transection of the optic nerve in adult newt Cynops pyrrhogaster. In the early phase of regeneration, each regenerating retinal axon sprouted several branches, in random directions within the tectum. As the regeneration proceeded, only branches directed toward the site of normal innervation were maintained, while the sproutings toward the ectopic part of the tectum were retracted or became atrophic. The surviving branches then sprouted several new branches. Sprouting of new branches and the disappearance of old branches occurred simultaneously throughout the process of regeneration. At the 10th week of regeneration, most regenerating retinal axons possessed branches only at the distal part within the site of normal innervation. These observations strongly suggest that the retinotopic central connection of regenerating retinal axons may be reestablished by means of a stepwise selection of widespread axonal branches.

Fluctuations of adenylate cyclase activity during anterior regeneration in Owenia fusiformis (Polychaete Annelid)

Biochemical assays of adenylate cyclase activity were performed during the early phases of regeneration in Owenia fusiformis (Polychaete Annelid). The results indicate the existence of a strong stimulation in an early phase following trauma. This stimulation is then followed by periodic fluctuations exhibiting a diurnal rhythm correlated with the cell cycle. Adenylate cyclase activity is also shown to be neurotransmitter-dependent. In this paper it is proposed that neurotransmitters might participate in the regulation of cyclic AMP formation, by means of adenylate cyclase acting on target blastema cells, undergoing the cell cycle.

DNA synthesis during the first stages of anterior regeneration in the polychaete annelid Owenia fusiformis (dedifferentiation and early phases of differentiation)

We have analysed DNA synthesis in early phases of regeneration in a marine Polychaete Annelid, Owenia fusiformis. The length and efficiency of the prereplicative phase was found to vary with the diurnal rhythm of activity of the animal; that is, it depends on the initial state of the cell population at the moment of the onset of proliferative stimulatin. When animals were operated on at 12 a.m., the duration of the prereplicative phase of the first cells stimulated to proliferate was found to be 12 h. The remaining cells entered the S-phase progressively in waves until the 3rd day following amputation when nearly 100% of the blastema cells were stimulated. At that time the cell-cycles of these dividing cells were found to be highly synchronized. Blastema differentiation takes place on the 4th day and is initiated by stomodeum formation. During the differentiation phase, DNA synthesis is restricted to small areas of the regenerating part. The system described is viewed as a new instrument for investigating the control of the cell cycle in synchronized and subsequently differentiating tissue cells.

Morphology of nuclear ribonucleoproteins in the early period of liver regeneration.

A cytochemical study on the nuclei of hepatocytes in the regenerating liver after partial hepatectomy by the method of Higgins and Anderson was carried out. The behaviour of the ribonucleoprotein components of the nucleus, using EDTA according to Bernhard, revealed altered proportions of the fibrillar and granular components of the nucleoli in the early phase of regeneration and morphologic changes in nuclear RNP, especially in perichromatin fibrils. At 6 h after hepatectomy, the reaction with perichromatin fibrils (FP) was intense, localized around fields of condensed chromatin, which suggests intense transcription of extranucleolar RNA. The behaviour of the remaining nuclear ribonucleoproteins was uncharacteristic.

Regeneration of intact spleen in a heterotropic site in splenectomized mice.

The regeneration of intact spleens implanted in the sacrospinal areas of splenectomized mice was studied by light microscopy. The weight of the implanted tissue was not fully regenerated 50 days after implantation. The pattern of embryonic development of the spleen was investigated and the histologic appearance of the implant 46 days after implantation resembled that of normal spleen. The appearance of primitive myelopoietic stem in cells in the early phases of regeneration makes this an attractive model in which to study the biologic effects of tumour viruses.

Changes in liver metabolites during forelimb regeneration in the adult newt, D. viridescens.

AbstractQuantitative extraction, histological, and histochemical procedures were used to investigate the effects of the stress of forelimb amputation on liver metabolites in the adult newt, D. viridescens. Results of these experiments showed that hepatic PAS responsive stores were depleted two hours through one week after amputation while protein decreased 24 hours — one week after amputation. There was no change in hepatic lipid. Hepatic GLU 6‐PDH and α‐glucan phosphorylase activities increased almost immediately after limb amputation and did not return to normal until one week and two weeks later, respectively. These and previous experiments suggest a systemic response to forelimb amputation whereby liver metabolites may initially provide energy reserves for escape and survival and then contribute to the early phases of regeneration.

Morphofunctional Differentiation in the Liver: 1. Influence of partial hepatectomy, cortisone and endotoxin on coordinated cellular activity during hepatic regeneration

The influence of endotoxin and cortisone on the function of hepatic cells was studied in relation to the effect of partial hepatectomy on their activity. The overall rate of clearance of carbon (K) suffered a diminution within the first few hours after surgery but carbon uptake per unit weight tissue was elevated as a result of hepatic resection. The K values were increased by endotoxin (100°g i.p.) alone or together with cortisone (1 mg i.p.) but the hormone alone lowered the clearance rates in high doses (5 mg i.p.). Treatment with either substance increased liver weight over and above the control level in early phases of regeneration and lowered it in the later phases. The actions of cortisone and endotoxin were not additive on either process. As regards the influence of cellular cycle on hormonally modified gene activity, refractoriness to the hypertrophic effect of cortisone (5 mg i.p. a dose which lowered the K value at all times) developed soon after hepatic resection and continued for at least 36 h after surgery. These and other results indicate that the RE cells remain susceptible to external influences throughout the regenerative cycle and do not passively follow the behaviour pattern of parenchyma. An active contribution of RE cells is further supported by the observation that regeneration was accompanied by a progressive increase in spleen weight. Furthermore, because uptake and binding of cortisone to ‘specific’ receptors progressed at least as well as in control mice at all these time periods, the refractoriness to cortisone action must lie at some stage beyond uptake, processing or association of steroid with the appropriate receptor. These data indicate the necessity to consider the behaviour of individual cell types in order to comprehend the integrated responses observed during growth, development and differentiation in the liver.

Glucose-6-phosphate dehydrogenase and malic enzyme in the normal and regenerating tail of the scincid lizard, Mabuya carinata.

The histochemical localization of glucose-6-phosphate dehydrogenase (G6PDH) and malic enzyme was carried out in the normal and regenerating tail of the scincid lizard, Mabuya carinata. The two enzymes follow an identical and parallel pattern of distribution, with the activity of G6PDH being perceptibly higher than that of malic enzyme. In the normal tail, the enzymes were poorly localized except for G6PDH activity in the skin. An increase in activity of both G6PDH and malic enzyme was noticed during early phases of regeneration of the tail with the peak value being attained during the blastemic and differentiation phases. Possible involvement of G6PDH in the synthesis of lipids and nucleic acids and that of malic enzyme in reduced nicotinamide adenine dinucleotide phosphate (NADPH2) yield is discussed. With the completion of regeneration, the levels of both enzymes return to normal levels.

Annual Testicular Cycle and Bill Color Change in the Eastern American Goldfinch

THE avian testicular cycle of seasonally-breeding birds consists of three phases: a regeneration phase when the tissues of the regressed gonad are reorganized, an acceleration phase characterized by development and growth of the testis, and a culmination phase in which the birds are responsive to certain environmental end stimuli that result in their nest building and gamete deposition (Marshall, 1961). Among wild populations of north-temperate passerines such a cycle has been demonstrated by histological examination of the testis in only a few early nesting species (e.g. Blanchard, 1941; Bullough, 1942; Blanchard and Erickson, 1949; Threadgold, 1956a, 1956b; Marshall and Coombs, 1957). Comparative study of the cycles of more species, particularly late nesters, is desirable. An analysis of seasonal changes in external characters that reflect seasonal changes in the gonad may provide an indirect method of determining the testis cycle in other species quickly. Bill color and postnuptial molt are well-suited for such an analysis as, in certain species, they are readily measurable from museum skins. Both characters have been correlated with changes in the titer of one or more of the gonadal hormones (Witschi and Fugo, 1940; Kobayashi, 1954a, 1954b, 1954c, 1958; Witschi, 1961; Engels, 1962), and Marshall (1961) associates the onset of the postnuptial molt with early regeneration phase and the termination of postnuptial molt with the onset of acceleration phase. The Eastern American Goldfinch, Spinus t. tristis, exhibits both a seasonal change in bill color and a late breeding season, and is principally single-brooded. Throughout the northern part of its range this goldfinch generally does not nest until July and later (Walkinshaw, 1938; Stokes, 1950; Nickell, 1951; Berger, 1968), and breeding behavior occurs seasonally later in this species than in other passerines nesting in northeastern North America. Field experiments conducted in Ithaca, New York revealed that not until late June or early July do female goldfinches begin gathering cotton artificially supplied them in their nesting habitat since early June, and they do not begin collecting thistle papus, a major natural nesting material, until July or, more rarely, in the last week of June (Mundinger, 1968). This correlates temporally with the onset of nest construction. In a study field in Ithaca only about 6 percent (2 of 35 nests) of all nests were initiated as early as the period mid-June to 1 July in 1963-65. Likewise the males do not engage in the defense of a geographically fixed area with flight song display and other territorial behaviors until nest construction begins or, in some cases, only a few days

On the oxygen consumption of Planaria vitta during starvation, the early phase of regeneration and asexual reproduction

Journal of Experimental ZoologyVolume 131, Issue 1 p. 123-135 Article On the oxygen consumption of Planaria vitta during starvation, the early phase of regeneration and asexual reproduction K. J. Pedersen, K. J. Pedersen Institute of General Zoology, University of CopenhagenSearch for more papers by this author K. J. Pedersen, K. J. Pedersen Institute of General Zoology, University of CopenhagenSearch for more papers by this author First published: February 1956 https://doi.org/10.1002/jez.1401310106Citations: 13AboutPDF ToolsRequest permissionExport citationAdd to favoritesTrack citation ShareShare Give accessShare full text accessShare full-text accessPlease review our Terms and Conditions of Use and check box below to share full-text version of article.I have read and accept the Wiley Online Library Terms and Conditions of UseShareable LinkUse the link below to share a full-text version of this article with your friends and colleagues. Learn more.Copy URL Share a linkShare onFacebookTwitterLinked InRedditWechat Citing Literature Volume131, Issue1February 1956Pages 123-135 RelatedInformation