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Repair Processes (repair + process)
Kinds of Repair Processes Selected AbstractsEnhanced Chondrogenesis and Wnt Signaling in PTH-Treated Fractures,JOURNAL OF BONE AND MINERAL RESEARCH, Issue 12 2007Sanjeev Kakar Abstract Studies have shown that systemic PTH treatment enhanced the rate of bone repair in rodent models. However, the mechanisms through which PTH affects bone repair have not been elucidated. In these studies we show that PTH primarily enhanced the earliest stages of endochondral bone repair by increasing chondrocyte recruitment and rate of differentiation. In coordination with these cellular events, we observed an increased level of canonical Wnt-signaling in PTH-treated bones at multiple time-points across the time-course of fracture repair, supporting the conclusion that PTH responses are at least in part mediated through Wnt signaling. Introduction: Since FDA approval of PTH [PTH(1,34); Forteo] as a treatment for osteoporosis, there has been interest in its use in other musculoskeletal conditions. Fracture repair is one area in which PTH may have a significant clinical impact. Multiple animal studies have shown that systemic PTH treatment of healing fractures increased both callus volume and return of mechanical competence in models of fracture healing. Whereas the potential for PTH has been established, the mechanism(s) by which PTH produces these effects remain elusive. Materials and Methods: Closed femoral fractures were generated in 8-wk-old male C57Bl/6 mice followed by daily systemic injections of either saline (control) or 30 ,g/kg PTH(1,34) for 14 days after fracture. Bones were harvested at days 2, 3, 5, 7, 10, 14, 21, and 28 after fracture and analyzed at the tissue level by radiography and histomorphometry and at the molecular and biochemical levels level by RNase protection assay (RPA), real-time PCR, and Western blot analysis. Results: Quantitative ,CT analysis showed that PTH treatment induced a larger callus cross-sectional area, length, and total volume compared with controls. Molecular analysis of the expression of extracellular matrix genes associated with chondrogenesis and osteogenesis showed that PTH treated fractures displayed a 3-fold greater increase in chondrogenesis relative to osteogenesis over the course of the repair process. In addition, chondrocyte hypertrophy occurred earlier in the PTH-treated callus tissues. Analysis of the expression of potential mediators of PTH actions showed that PTH treatment significantly induced the expression of Wnts 4, 5a, 5b, and 10b and increased levels of unphosphorylated, nuclear localized ,-catenin protein, a central feature of canonical Wnt signaling. Conclusions: These results showed that the PTH-mediated enhancement of fracture repair is primarily associated with an amplification of chondrocyte recruitment and maturation in the early fracture callus. Associated with these cellular effects, we observed an increase in canonical Wnt signaling supporting the conclusion that PTH effects on bone repair are mediated at least in part through the activation of Wnt-signaling pathways. [source] Paradoxical enhancement of oxidative cell injury by overexpression of heme oxygenase-1 in an anchorage-dependent cell ECV304JOURNAL OF CELLULAR BIOCHEMISTRY, Issue 3 2004Keiko Maruhashi Abstract There has been increasing evidence suggesting the potent anti-inflammatory roles of heme oxygenase-1 (HO-1) in protecting renal tubular epithelial cells, vascular endothelial cells, and circulating monocytes. Based on these findings, novel therapeutic interventions have been proposed to control the expression of endothelial HO-1 levels to ameliorate various vascular diseases. We evaluated the effect of HO-1 gene transfer into an anchorage-dependent cell, ECV304. Effect of HO-1 production on the cell injury induced by hydrogen peroxide was evaluated after hemin stimulation and after HO-1 gene transfection. Morphological changes and the induction of various anti-apoptotic proteins were examined at the same time. Levels of HO-1 expression were variable in different clones of HO-1-transfected ECV304 cells. Among these, the clones with moderate levels of HO-1 expression were significantly more resistant to oxidative stress. In contrast, those with the highest levels of HO-1 exhibited paradoxically enhanced susceptibility to oxidative injury. Interestingly, the cell survival after oxidative stress was in parallel with the levels of Bcl-2 expression and of fibronectin receptor, ,5 integrin. It is suggested from these results, that excessive HO-1 not only leads to enhanced cell injury, but also prolongs the repair process of the injured endothelial tissue. However, HO-1 reduces the oxidative cell injury and protects the endothelial cells, if its expression is appropriately controlled. © 2004 Wiley-Liss, Inc. [source] Skeletal muscle fiber type conversion during the repair of mouse soleus: Potential implications for muscle healing after injuryJOURNAL OF ORTHOPAEDIC RESEARCH, Issue 11 2007Tetsuya Matsuura Abstract We used a mouse model of cardiotoxin injury to examine fiber type conversion during muscle repair. We evaluated the soleus muscles of 37 wild-type mice at 2, 4, 8, and 12 weeks after injury. We also used antibodies (fMHC and sMHC) against fast and slow myosin heavy chain to classify the myofibers into three categories: fast-, slow-, and mixed (hybrid)-type myofibers (myofibers expressing both fMHC and sMHC). Our results revealed an increase in the percentage of slow-type myofibers and a decrease in the percentage of fast-type myofibers during the repair process. The percentage of hybrid-type myofibers increased 2 weeks after injury, then gradually decreased over the following 6 weeks. Similarly, our analysis of centronucleated myofibers showed an increase in the percentage of slow-type myofibers and decreases in the percentages of fast- and hybrid-type myofibers. We also investigated the relationship between myofiber type conversion and peroxisome proliferator-activated receptor-, coactivator-1, (PGC-1,). The expression of both PGC-1, protein, which is expressed in both the nucleus and the cytoplasm of regenerating myofibers, and sMHC protein increased with time after cardiotoxin injection, but we observed no significant differential expression of fMHC protein in regenerating muscle fibers during muscle repair. PGC-1,-positive myofibers underwent fast to slow myofiber type conversion during the repair process. These results suggest that PGC-1, contributes to myofiber type conversion after muscle injury and that this phenomenon could influence the recovery of the injured muscle. © 2007 Orthopaedic Research Society. Published by Wiley Periodicals, Inc. J Orthop Res 25:1534,1540, 2007 [source] Hepatocyte growth factor induction of macrophage chemoattractant protein-1 and osteophyte-inducing factors in osteoarthritisJOURNAL OF ORTHOPAEDIC RESEARCH, Issue 5 2007Berno Dankbar Abstract In osteoarthritis (OA), hepatocyte growth factor (HGF) is supposed to play a role in cartilage repair. Because the development of osteophytes is a major characteristic of OA and thought to be part of an attempted repair process, the purpose of this study was to determine whether HGF may be involved in osteophyte formation. HGF levels in synovial fluids from 41 patients assessed by enzyme immunosorbant assay were correlated with disease severity and osteophyte formation, evaluated by anteroposterior weight-bearing radiographs. Detection of HGF, c-Met, and CD68 in cartilage and synovial tissues was assessed by immunohistochemistry. Effects of HGF on the secretion of TGF-,1 and BMP-2 by chondrocytes, fibroblast-like synovial cells (FLS), and macrophages as well as HGF-induced secretion of MCP-1 by FLS and chondrocytes were determined by ELISA. HGF was detected in all synovial fluids and concentrations correlated highly with disease severity and osteophyte formation (p,<,0.001). Immunohistochemistry revealed weak synovial staining for HGF, whereas increasing numbers of HGF expressing chondrocytes were detected depending on disease severity. In addition, an increased number of macrophages in synovial specimens was observed, which was likewise severity dependent. In a series of subsequent in vitro studies, HGF remarkable induced MCP-1 secretion by FLS in a dose-dependent manner. No effect on TGF-,1 and BMP-2 secretion by FLS and chondrocytes was evident upon HGF stimulation, whereas secretion of these growth factors by PMA-differentiated THP-1 cells was significantly increased by HGF. The results indicate that HGF may facilitate osteophyte development by promoting MCP-1-mediated entry of monocytes/macrophages into the OA-affected joint and/or by stimulating macrophage-derived growth factors. © 2007 Orthopaedic Research Society. Published by Wiley Periodicals, Inc. J Orthop Res 25:569,577, 2007 [source] Acceleration of cartilage repair by genetically modified chondrocytes over expressing bone morphogenetic protein-7JOURNAL OF ORTHOPAEDIC RESEARCH, Issue 4 2003Chisa Hidaka Background: Cartilage has a limited capacity to heal. Although chondrocyte transplantation is a useful therapeutic strategy, the repair process can be lengthy. Previously we have shown that over expression of bone morphogenetic protein-7 (BMP-7) in chondrocytes by adenovirus-mediated gene transfer leads to increased matrix synthesis and cartilage-like tissue formation in vitro. In this context we hypothesized that implantation of genetically modified chondrocytes expressing BMP-7 would accelerate the formation of hyaline-like repair tissue in an equine model of cartilage defect repair. Methods: Chondrocytes treated with adenovirus vector encoding BMP-7 (AdBMP-7) or as control, an adenovirus vector encoding an irrelevant gene (Escherichia coli cytosine deaminase, AdCD) were implanted into extensive (15 mm diameter) articular cartilage defects in the patellofemoral joints of 10 horses. Biopsies were performed to evaluate early healing at 4 weeks. At the terminal time point of 8 months, repairs were assessed for morphology, MRI appearance, compressive strength, biochemical composition and persistence of implanted cells. Results: Four weeks after surgery AdBMP-7-treated repairs showed an increased level of BMP-7 expression and accelerated healing, with markedly more hyaline-like morphology than control. Quantitative real-time polymerase chain reaction (PCR) analysis of the repair tissue 8 months after surgery showed that few implanted cells persisted. By this time, the controls had healed similarly to the AdBMP-7-treated defects, and no difference was detected in the morphologic, biochemical or biomechanical properties of the repair tissues from the two treatment groups. Conclusions: Implantation of genetically modified chondrocytes expressing BMP-7 accelerates the appearance of hyaline-like repair tissue in experimental cartilage defects. Clinical relevance: Rehabilitation after cell-based cartilage repair can be prolonged, leading to decreased patient productivity and quality of life. This study shows the feasibility of using genetically modified chondrocytes to accelerate cartilage healing. © 2003 Orthopaedic Research Society. Published by Elsevier Science Ltd. All rights reserved. [source] Adhesion of perichondrial cells to a polylactic acid scaffoldJOURNAL OF ORTHOPAEDIC RESEARCH, Issue 4 2003Alexander Giurea Abstract The number of chondrogenic cells available locally is an important factor in the repair process for cartilage defects. Previous studies demonstrated that the number of transplanted rabbit perichondrial cells (PC) remaining in a cartilage defect in vivo, after being carried into the site in a polylactic acid (PLA) scaffold, declined markedly within two days. This study examined the ability of in vitro culture of PC/PLA constructs to enhance subsequent biomechanical stability of the cells and the matrix content in an in vitro screening assay. PC/PLA constructs were analyzed after 1 h, 1 and 2 weeks of culture. The biomechanical adherence of PC to the PLA scaffold was tested by subjecting the PC/PLA constructs to a range of flow velocities (0.25,25 mm/s), spanning the range estimated to occur under conditions of construct insertion in vivo. The adhesion of PC to the PLA carrier was increased significantly by 1 and 2 weeks of incubation, with 25 mm/s flow causing a 57% detachment of cells after 1 h of seeding, but only 7% and 16% after 1 and 2 weeks of culture, respectively (p > 0.001). This adherence was associated with marked deposition of glycosaminoglycan and collagen. These findings suggest that pre-incubation of PC-laden PLA scaffolds markedly enhances the stability of the indwelling cells. © 2003 Orthopaedic Research Society. Published by Elsevier Science Ltd. All rights reserved. [source] EVIDENCE OF A LATENT OXIDATIVE BURST IN RELATION TO WOUND REPAIR IN THE GIANT UNICELLULAR CHLOROPHYTE DASYCLADUS VERMICULARIS,JOURNAL OF PHYCOLOGY, Issue 3 2005Cliff Ross We investigated the kinetics and composition of the second phase of the wound repair process of Dasycladus vermicularis ([Scropoli] Krasser) using fluorescent probes, chromatography, UV spectroscopy, and histochemistry. Our new evidence supports the hypothesis that the second phase of wound repair (initiated at approximately 35,45 min postinjury) is based on the activation of an oxidative burst that produces micromolar H2O2 levels. These results provide evidence of peroxidase activity at the wound site, real-time measurements of an oxidative burst, and catechol localization in wound plugs. Strong evidence is presented indicating that the biochemical machinery exists for oxidative cross-linking to ensue in the wound-healing process of D. vermicularis. [source] Sheep embryonic stem-like cells transplanted in full-thickness cartilage defectsJOURNAL OF TISSUE ENGINEERING AND REGENERATIVE MEDICINE, Issue 3 2009Maria Dattena Abstract Articular cartilage regeneration is limited. Embryonic stem (ES) cell lines provide a source of totipotent cells for regenerating cartilage. Anatomical, biomechanical, physiological and immunological similarities between humans and sheep make this animal an optimal experimental model. This study examines the repair process of articular cartilage in sheep after transplantation of ES-like cells isolated from inner cell masses (ICMs) derived from in vitro -produced (IVP) vitrified embryos. Thirty-five ES-like colonies from 40 IVP embryos, positive for stage-specific embryonic antigens (SSEAs), were pooled in groups of two or three, embedded in fibrin glue and transplanted into osteochondral defects in the medial femoral condyles of 14 ewes. Empty defect (ED) and cell-free glue (G) in the controlateral stifle joint served as controls. The Y gene sequence was used to detect ES-like cells in the repair tissue by in situ hybridization (ISH). Two ewes were euthanized at 1 month post-operatively, three each at 2 and 6 months and four at 12 months. Repairing tissue was examined by biomechanical, macroscopic, histological, immunohistochemical (collagen type II) and ISH assays. Scores of all treatments showed no statistical significant differences among treatment groups at a given time period, although ES-like grafts showed a tendency toward a better healing process. ISH was positive in all ES-like specimens. This study demonstrates that ES-like cells transplanted into cartilage defects stimulate the repair process to promote better organization and tissue bulk. However, the small number of cells applied and the short interval between surgery and euthanasia might have negatively affected the results. Copyright © 2009 John Wiley & Sons, Ltd. [source] Mucinous cystadenoma of the pancreas with huge mural hematomaPATHOLOGY INTERNATIONAL, Issue 10 2009Takeshi Hisa A 60-year-old woman was referred for evaluation of a cystic mass in the pancreatic body that extended to the tail. Transabdominal ultrasonography demonstrated an oval cystic mass 24 cm in diameter, filled with debris. On the cyst wall there was a wide-based, smooth-surfaced, heterogeneous high-echoic protrusion that was 5 cm in diameter. On CT the protrusion showed internal enhancement. Endoscopic pancreatography showed no intraductal mucin or communication with the cyst. A distal pancreatectomy was performed under the diagnosis of mucinous cystadenocarcinoma. Grossly there was a brownish, hemispherical protrusion into the thin monolocular cyst. The cut surface of the protrusion showed a peripheral yellow-brownish area and an internal wine-colored area. Histopathologically the cyst wall consisted of tall columnar cells without atypical nuclei, ovarian-type stroma beneath the epithelium, and fibrotic tissue with abundant capillary vessels, suggestive of a mucinous cystadenoma. The protrusion was composed of peripheral organized hematoma without a covering epithelium, and internal hemorrhage and many capillary vessels, with no evidence of tumor cell necrosis. These histopathological findings appear to be similar to those of chronic expanding hematoma. The formation of a huge mural hematoma in a mucinous cystic neoplasm can occur as a repair process after the breaking of intrawall vessels. [source] Regulation of targeted gene repair by intrinsic cellular processesBIOESSAYS, Issue 2 2009Julia U. Engstrom Targeted gene alteration (TGA) is a strategy for correcting single base mutations in the DNA of human cells that cause inherited disorders. TGA aims to reverse a phenotype by repairing the mutant base within the chromosome itself, avoiding the introduction of exogenous genes. The process of how to accurately repair a genetic mutation is elucidated through the use of single-stranded DNA oligonucleotides (ODNs) that can enter the cell and migrate to the nucleus. These specifically designed ODNs hybridize to the target sequence and act as a beacon for nucleotide exchange. The key to this reaction is the frequency with which the base is corrected; this will determine whether the approach becomes clinically relevant or not. Over the course of the last five years, workers have been uncovering the role played by the cells in regulating the gene repair process. In this essay, we discuss how the impact of the cell on TGA has evolved through the years and illustrate ways that inherent cellular pathways could be used to enhance TGA activity. We also describe the cost to cell metabolism and survival when certain processes are altered to achieve a higher frequency of repair. [source] Extensive Cortical Remyelination in Patients with Chronic Multiple SclerosisBRAIN PATHOLOGY, Issue 2 2007Monika Albert MD Recent studies revealed prominent cortical demyelination in patients with chronic multiple sclerosis (MS). Demyelination in white matter lesions is frequently accompanied by remyelination. This repair process, however, often remains incomplete and restricted to the lesion border. In the present study, we examined the frequency and extent of remyelination in cortical and white matter lesions in autopsy brain tissue of 33 patients with chronic MS. The majority of patients (29 of 33) harbored cortical demyelination. Remyelination of cortical lesions was identified light microscopically by the presence of thin and irregularly arranged myelin sheaths, and confirmed by electron microscopy. Extensive remyelination was found in 18%, remyelination restricted to the lesion border in 54%, and no remyelination in 28% of cortical lesions. A direct comparison of the extent of remyelination in white matter and cortical lesions of the same patients revealed that remyelination of cortical lesions was consistently more extensive. In addition, g-ratios of fibers in areas of "normal appearing cortex" yielded values consistent with remyelination. Our data confirm the high prevalence of cortical demyelination in chronic MS and imply that the propensity to remyelinate is high in cortical MS lesions. [source] Impaired removal of DNA interstrand cross-link in Nijmegen breakage syndrome and Fanconi anemia, but not in BRCA-defective groupCANCER SCIENCE, Issue 11 2008Ken Tsuchida Human diseases characterized by a high sensitivity to DNA interstrand cross-links (ICL) and predisposition to malignance include Nijmegen breakage syndrome (NBS) and Fanconi anemia (FA), which is further classified to three groups: (1) FA core-complex group; (2) FA-ID complex group; and (3) breast cancer (BRCA)-defective group. The relationships between these four groups and the basic defect in ICL repair remain unclear. To study the details of ICL repair in NBS and FA, a highly sensitive PPB (psoralen,polyethylene oxide,biotin) dot blot assay was developed to provide sensitive quantitative measurements of ICL during the removal process. Studies utilizing this assay demonstrated a decreased rate of ICL removal in cells belonging to the FA core-complex group (e.g. groups A and G) and FA-ID complex group (group D2), while ICL removal was restored to normal levels after these cells were complemented with wt-FANCA, wt-FANCG and wt-FANCD2. Conversely, FA-D1 cells with a defective BRCA2 protein displayed normal ICL removal, although they were compromised with respect to recombination. This normal ICL removal rate in recombination-deficient cells was confirmed by using XRCC3-defective Chinese hamster cells, which are similarly compromised with respect to recombination and are sensitive to mitomycin C. The present study also showed that cells from patients with Nijmegen breakage syndrome were defective in ICL removal, while they were impaired in the recombination. These results indicate an obvious defect of FA and NBS in the ICL repair process, except in the BRCA-defective group, and a separate step of recombination-mediated repair pathway between the BRCA group and NBS. (Cancer Sci 2008; 99: 2238,2243) [source] DNA repair and cancer: Lessons from mutant mouse modelsCANCER SCIENCE, Issue 2 2004Takatoshi Ishikawa DNA damage, if the repair process, especially nucleotide excision repair (NER), is compromised or the lesion is repaired by some other error-prone mechanism, causes mutation and ultimately contributes to neoplastic transformation. Impairment of components of the DNA damage response pathway (e.g., p53) is also implicated in carcinogenesis. We currently have considerable knowledge of the role of DNA repair genes as tumor suppressors, both clinically and experimentally. The deleterious clinical consequences of inherited defects in DNA repair system are apparent from several human cancer predisposition syndromes (e.g., NER-compromised xeroderma pigmentosum [XP] and p53 -deficient Li-Fraumeni syndrome). However, experimental studies to support the clinical evidence are hampered by the lack of powerful animal models. Here, we review in vivo experimental data suggesting the protective function of DNA repair machinery in chemical carcinogenesis. We specifically focus on the three DNA repair genes, O6 -methylguanine-DNA methyltransferase gene (MGMT), XP group A gene (XPA) and p53. First, mice overexpressing MGMT display substantial resistance to nitrosamine-induced hepatocarcinogenesis. In addition, a reduction of spontaneous liver tumors and longer survival times were evident. However, there are no known mutations in the human MGMT and therefore no associated cancer syndrome. Secondly, XPA mutant mice are indeed prone to spontaneous and carcinogen-induced tumorigenesis in internal organs (which are not exposed to sunlight). The concomitant loss of p53 resulted in accelerated onset of carcinogenesis. Finally, p53 null mice are predisposed to brain tumors upon transplacental exposure to a carcinogen. Accumulated evidence in these three mutant mouse models firmly supports the notion that the DNA repair system is vital for protection against cancer. [source] Interleukin1-Induced apoptosis of keratocytes: effect of biglycanACTA OPHTHALMOLOGICA, Issue 2007M KOULIKOVSKA Purpose: Biglycan is absent in the normal cornea, but UVR exposure leads to a significant expression of the biglycan gene in the rabbit cornea, an effect that decreases after healing is completed, indicating the envolvement of biglycan in the corneal repair process. In the present study, we have investigated possible involvement of biglycan in the modulation of the survival of keratocytes. Methods: Keratocytes were grown either under serum free conditions to obtain quiescent keratocyte cell culture or in the presence of 10% fetal bovine serum to induce keratocyte transformation into myofibroblasts. Myofibroblastic phenotype was confirmed by immunocytochemistry with anti-alpha-smooth muscle actin antibodies. Cell death was induced in both cell cultures by interleukin-1 in the presence or absence of biglycan. Histone-associated DNA fragments were assayed by using a cell death detection ELISA. Results: Quantification of histone-associated DNA fragments by the cell death detection ELISA showed that biglycan strongly protected quiescent keratocytes from dying whereas it enhanced the death rate of transformed keratocytes. Apoptotic death rate was elevated after the addition of IL-1 in both keratocyte and myofibroblast cell cultures. Co-incubation with biglycan markedly reduced the number of apoptotic keratocytes but markedly increased the number of apoptotic myofibroblasts. Conclusions: IL-1-induces apoptosis of both quiescent and transformed keratocytes. However, biglycan has differential effect on apoptosis of these two cell types. [source] ANABOLIC AGENTS FOR IMPROVING MUSCLE REGENERATION AND FUNCTION AFTER INJURYCLINICAL AND EXPERIMENTAL PHARMACOLOGY AND PHYSIOLOGY, Issue 7 2008Gordon S Lynch SUMMARY 1In the present review, we describe how muscles can be injured by external factors, internal factors or during the performance of some actions during sports. In addition, we describe the injury to a muscle that occurs when its blood supply is interrupted, an occurrence common in clinical settings. An overview of muscle regeneration is presented, as well as a discussion of some of the potential complications that can compromise successful muscle repair and lead to impaired function and permanent disability. 2Improving muscle regeneration is important for hastening muscle repair and restoring muscle function and the present review describes ways in which this can be achieved. We describe recent advances in tissue engineering that offer considerable promise for treating muscle damage, but highlight the fact that these techniques require rigorous evaluation before they can become mainstream clinical treatments. 3Growth-promoting agents are purported to increase the size of existing and newly regenerating muscle fibres and, therefore, could be used to improve muscle function if administered at appropriate times during the repair process. The present review provides an update on the efficacy of some growth-promoting agents, including anabolic steroids, insulin-like growth factor-I (IGF-I) and b2 -adrenoceptor agonists, to improve muscle function after injury. Although these approaches have clinical merit, a better understanding of the androgenic, IGF-I and b-adrenoceptor signalling pathways in skeletal muscle is important if we are to devise safe and effective therapies to enhance muscle regeneration and function after injury. [source] Shift in birch leaf metabolome and carbon allocation during long-term open-field ozone exposureGLOBAL CHANGE BIOLOGY, Issue 5 2007SARI KONTUNEN-SOPPELA Abstract Current and future ozone concentrations have the potential to reduce plant growth and increase carbon demand for defence and repair processes, which may result in reduced carbon sink strength of forest trees in long-term. Still, there is limited understanding regarding the alterations in plant metabolism and variation in ozone tolerance among tree species and genotypes. Therefore, this paper aims to study changes in birch leaf metabolome due to long-term realistic ozone stress and to relate these shifts in the metabolism with growth responses. Two European white birch (Betula pendula Roth) genotypes showing different ozone sensitivity were growing under 1.4,1.7 × ambient ozone in open-field conditions in Central Finland. After seven growing seasons, the trees were analysed for changes in leaf metabolite profiling, based on 339 low molecular weight compounds (including phenolics, polar and lipophilic compounds, and pigments) and related whole-tree growth responses. Genotype caused most of the variance of metabolite concentrations, while ozone concentration was the second principal component explaining the metabolome profiling. The main ozone caused changes included increases in quercetin-phenolic compounds and compounds related to leaf cuticular wax layer, whereas several compounds related to carbohydrate metabolism and function of chloroplast membranes and pigments (such as chlorophyll-related phytol derivatives) were decreasing. Some candidate compounds such as surface wax-related squalene, 1-dotriacontanol, and dotriacontane, providing growth-related tolerance against ozone were demonstrated. This study indicated that current growth-based ozone risk assessment methods are inadequate, because they ignore ecophysiological impacts due to alterations in leaf chemistry. [source] Molecular response to climate change: temperature dependence of UV-induced DNA damage and repair in the freshwater crustacean Daphnia pulicariaGLOBAL CHANGE BIOLOGY, Issue 4 2004Emily J. MacFadyen Abstract In temperate lakes, asynchronous cycles in surface water temperatures and incident ultraviolet (UV) radiation expose aquatic organisms to damaging UV radiation at different temperatures. The enzyme systems that repair UV-induced DNA damage are temperature dependent, and thus potentially less effective at repairing DNA damage at lower temperatures. This hypothesis was tested by examining the levels of UV-induced DNA damage in the freshwater crustacean Daphnia pulicaria in the presence and absence of longer-wavelength photoreactivating radiation (PRR) that induces photoenzymatic repair (PER) of DNA damage. By exposing both live and dead (freeze-killed) Daphnia as well as raw DNA to UV-B in the presence and absence of PRR, we were able to estimate the relative importance and temperature dependence of PER (light repair), nucleotide excision repair (NER, dark repair), and photoprotection (PP). Total DNA damage increased with increasing temperature. However, the even greater increase in DNA repair rates at higher temperatures led net DNA damage (total DNA damage minus repair) to be greater at lower temperatures. Photoprotection accounted for a much greater proportion of the reduction in DNA damage than did repair. Experiments that looked at survival rates following UV exposure demonstrated that PER increased survival rates. The important implication is that aquatic organisms that depend heavily on DNA repair processes may be less able to survive high UV exposure in low temperature environments. Photoprotection may be more effective under the low temperature, high UV conditions such as are found in early spring or at high elevations. [source] In vivo Engineering of Tissues: Biological Considerations, Challenges, Strategies, and Future DirectionsADVANCED MATERIALS, Issue 32-33 2009V. Prasad Shastri Abstract Moving forward materials-based regenerative medicine faces many challenges to ensure clinical success. Many of these challenges lie at the interface of molecular/structural biology and materials science. This review discusses this issue from a biological and material view-point, highlighting key biological processes and variables that can impact the repair processes. From a materials design stand point, developing materials that can promote healing over scarring is the key. All indicators suggest that polymeric materials are most well-suited for de novo engineering of tissues. In addition to biomolecular signals that are involved in controlling the fate of cells and neo-tissue morphogenesis at the site of implantation, this review also discusses recent advances in design of highly functional injectable biomaterials, that show promise in controlling local biological processes. [source] Pulsed Signal Therapy® for the treatment of musculoskeletal conditions: a millennium paradigmINTERNATIONAL JOURNAL OF RHEUMATIC DISEASES, Issue 3 2004Richard MARKOLL Abstract Reports and reviews from various sources, including the World Health Organization and United Nations Population Division, confirm the general increasing trend in the ageing population groups worldwide. There are over 150 types of musculoskeletal conditions, with rheumatoid arthritis, osteoarthritis, osteoporosis, low back pain and limb trauma, accounting for the greatest impact on the population at large. Osteoarthritis (OA) is predicted to become the fourth leading cause of disability by the year 2020. The most common medication prescribed for OA is non-steroidal anti-inflammatory drugs (NSAIDs). These have long been associated with numerous adverse effects, are costly and short-term in their ,therapeutic' effect. Pulsed Signal Therapy® (PSTÔ) is an innovative treatment modality for musculoskeletal conditions. It has been commercially available since 1992, is currently employed in at least 800 clinics and/or medical institutes, and to-date, no adverse effects have been reported. Furthermore, it is non-invasive, non-pharmacological, painless, with long-term follow-up, and sustained efficacy. When connective tissue is injured and physiological signalling is disturbed or absent, PSTÔ, as the external, biophysical signal (stimulus) of physiological energy parameters and waveform, passively induces ,fluid flow' in the injured area, creating ,streaming potentials', that induce biophysical-biochemical coupling, subsequent signal transduction, to activate repair and regenerative processes. In doing so, it restores the innate, physiological signalling to enable these regenerative and repair processes to continue naturally. [source] Expression of Dishevelled-1 in wound healing after acute myocardial infarction: possible involvement in myofibroblast proliferation and migrationJOURNAL OF CELLULAR AND MOLECULAR MEDICINE, Issue 2 2004Lijun Chen Abstract One of our previous studies indicated that the expression of ,-catenin, which is the key factor of wnt-frizzled pathway, increased significantly in the ischemic area of the rat heart 7 days after myocardial infarction (MI). Together with the results of other recent studies, we made an assumption that wnt-frizzled pathway may be involved in the controlled cell proliferation and migration during repair processes after MI. To verify this assumption we tried to investigate the expression of another signal transduction molecule called Dishevelled in wnt-frizzled pathway during the wound healing process after MI. The left descending coronary arteries of rats were ligated to induce MI. Immunohistochemistry SABC method and in situ hybridization were performed to detect the expression of Dishevelled-1. The results showed, that one day after MI, Dishevelled-1 mRNA but not protein expression was detected in the cells at the border zone of the infarction area; 4 days after MI the expression of Dishevelled-1 increased exclusively and cytoplasmic Dishevelled-1 was observed not only at the border zone but also in the infarct area; 7 days after MI, it seems that the expression reached its peak, the positive staining even spread into the endothelial and smooth muscle cells of the newly formed and pre-existing blood vessels in the infarction area; after that the Dishevelled-1 expression decreased abruptly and could hardly be detected 28 days after MI. Thus cytoplasmic Dishevelled-1 may be involved in the controlled proliferation and migration of myofibroblasts and vascular endothelial cells, hence play a role during the wound healing process after MI. [source] Oxidative damage to DNA and lipids: correlation with protein glycation in patients with type 1 diabetesJOURNAL OF CLINICAL LABORATORY ANALYSIS, Issue 2 2010Mohammad Taghi Goodarzi Abstract Diabetic hyperglycemia is associated with increased production of reactive oxygen species (ROS). ROS reacts with DNA resulting in various products, such as 8-hydroxydeoxyguanosine (8-OHdG), that excrete in urine owing to DNA repair processes. Urinary 8-OHdG has been proposed as an indicator of oxidative damage to DNA. This study aimed to evaluate relationship between oxidative damage to DNA and protein glycation in patients with Type 1 diabetes. We measured urinary 8-OHdG level in diabetic patients and healthy subjects and discussed its relationship to glycated hemoglobin (HbA1c) and glycated serum protein (GSP) levels. Furthermore plasma malondialdehyde (MDA) level monitored as an important indicator of lipid peroxidation in diabetes. We studied 32 patients with Type 1 diabetes mellitus and compared the measured factors with those of 48 age-matched nondiabetic controls. GSP and MDA were measured bycolorimetric assay. Urinary 8-OHdG measurement was carried out using ELISA. In this study urinary 8-OHdG, HbA1c, plasma MDA, and GSP levels were progressively higher in diabetics than in control subjects (P<0.05). Furthermore we found significant correlation between urinary 8-OHdG and HbA1c (P<0.05) in diabetic group. Correlation between fasting blood sugar and GSP were significant. We also found significant correlation between fasting blood sugar and MDA. This case,control study in young diabetic patients showed increased blood glucose and related metabolic disorders result in oxidative stress and oxidative damage to DNA and lipids. Furthermore oxidative damage to DNA is associated to glycemic control level, whereas lipid peroxidation level was not significantly correlated with glycemic control level. J. Clin. Lab. Anal. 24:72,76, 2010. © 2010 Wiley-Liss, Inc. [source] Decorin antisense gene therapy improves functional healing of early rabbit ligament scar with enhanced collagen fibrillogenesis in vivoJOURNAL OF ORTHOPAEDIC RESEARCH, Issue 4 2000Norimasa Nakamura Injured ligaments heal with scar tissue, which has mechanical properties inferior to those of normal ligament, potentially resulting in re-injury, joint instability, and subsequent degenerative arthritis. In ligament scars, normal large-diameter collagen fibrils have been shown to be replaced by a homogenous population of small collagen fibrils. Because collagen is a major tensile load-bearing matrix element and because the proteoglycan decorin is known to inhibit collagen fibrillogenesis, we hypothesized that the restoration of larger collagen fibrils in a rabbit ligament scar, by down-regulating the proteoglycan decorin, would improve the mechanical properties of scar. In contrast to sense and injection-treated controls, in vivo treatment of injured ligament by antisense decorin oligodeoxynucleotides led to an increased development of larger collagen fibrils in early scar and a significant improvement in both scar failure strength (83,85% improvement at 6 weeks; p < 0.01) and scar creep elongation (33,48% less irrecoverable creep; p < 0.03) under loading. This is the first report that in vivo manipulation of collagen fibrillogenesis improves tissue function during repair processes with gene therapy. These findings not only suggest the potential use of this type of approach to improve the healing of various soft tissues (skin, ligament, tendon, and so on) but also support the use of such methods to better understand specific structure-function relationships in scars. [source] Regeneration of large bone defects in sheep using bone marrow stromal cellsJOURNAL OF TISSUE ENGINEERING AND REGENERATIVE MEDICINE, Issue 5 2008P. Giannoni Abstract Bone repair was addressed in a critical-sized defect model in sheep, combining a ceramic biomaterial and mesenchymal progenitor cells. The defects in the tibial mid-diaphysis were treated with autologous bone or with a silicon-stabilized tricalcium phosphate biomaterial, implemented or not by the addition of expanded bone marrow stromal cells. An internal locking compression plate and an external fixator were applied for stabilization. Radiographies were taken during the 8 months follow-up: the pixel grey levels of the lesion areas were determined to evaluate the repair process radiologically. Microradiography, histology and vascular density tests were performed. The autologous bone-treated group performed best, as assessed radiologically, within 20,24 weeks after surgery. Very limited healing was detected in the other experimental group: a partial bone deposition occurred at the periphery of the bony stumps only in the cell-seeded scaffolds. Interestingly, this effect ended within 20,24 weeks, as for the autologous bone, suggesting similar kinetics of the repair processes involved. Moreover, bone deposition was located where a significant reduction of the ceramic scaffold was detected. Faxitron microradiography and histology data confirmed these results. Vascular density analysis evidenced that cell-seeded scaffolds supported an increased vascular ingrowth. Thus, the interactions with the proper microenvironment and the oxygen and nutrient supply in the inner part of the constructs seem fundamental to initiate scaffold substitution and to improve cell performance in tissue-engineered approaches to bone repair. Copyright © 2008 John Wiley & Sons, Ltd. [source] Association between TP53 gene ARG72PRO polymorphism and chromosome aberrations in human cancersMOLECULAR CARCINOGENESIS, Issue 6 2010Nicolay V. Litviakov Abstract It is well known that the TP53 gene considerably influences on DNA repair processes. Polymorphisms in the TP53 gene, particularly the well-known Arg72Pro in codon 72 of exon 4 (Ex4+119 G>C; rs1042522), can modify the functionality of the p53 protein and activation of DNA repair. Actually, polymorphic variants Arg and Pro were found to have different properties of regulation of TP53-dependent DNA repair target genes, that can effect various levels of chromosome aberrations in cancer patients with these genotypes. Here, we studied frequency of chromatid breaks (CB), chromosome-type aberrations (CTA) and aberrant cells (AC) in cancer patients (n,=,102) with various Arg72Pro genotypes. It was shown that the Arg variant of TP53 gene is associated with high frequency of AC and chromatid breaks. That is Arg/Arg carriers have more different chromosome aberrations in comparison to individuals with Arg/Pro and Pro/Pro genotypes (P,<,0.05). Conversely, the lowest level of AC and chromatid breaks were detected in cancer patients with the Pro/Pro genotype. A completely unexpected result was that women with Arg/Arg genotype had the most high frequency of CB and AC in comparison to Arg/Pro and Pro/Pro women carriers (P,<,0.001). In the group of male patients we did not show any differences in chromosome aberrations between carriers of Arg72Pro genotypes. In conclusion, the TP53 gene Arg72Pro polymorphism appreciably influence on occurrence of chromosome aberrations in cancer. Mol. Carcinog. © 2010 Wiley-Liss, Inc. [source] On the mechanism of loading the PCNA sliding clamp by RFCMOLECULAR MICROBIOLOGY, Issue 1 2008Isabelle Dionne Summary Sliding clamps play central roles in a broad range of DNA replication and repair processes. The clamps form circular molecules that must be opened and resealed around DNA by the clamp loader complex to fulfil their function. While most eukaryotes and many archea possess a homo-trimeric PCNA, the PCNA of Sulfolobus solfataricus is a heterotrimer. Here, we exploit the asymmetry of S. solfataricus PCNA to create a series of circularly permuted PCNA subunit fusions, thereby covalently closing defined interfaces within the heterotrimer. Using these concatamers, we investigate the requirements for loading the clamp onto DNA and reveal that a single defined interface within the heterotrimer is opened during the loading process. Subunit,specific interactions between S. solfataricus RFC clamp loader and PCNA permit us to superimpose our data upon the structure of yeast RFC,PCNA complex, thereby presenting a general model for PCNA loading by RFC in archaea and eukaryotes. [source] Iron availability regulates DNA recombination in Neisseria gonorrhoeaeMOLECULAR MICROBIOLOGY, Issue 5 2000Carla D. Serkin The pilus of Neisseria gonorrhoeae (the gonococcus Gc), the causative agent of gonorrhoea, promotes attachment of the gonococcus to the host epithelium and is essential for the establishment of disease. The ability of N. gonorrhoeae to infect previously exposed individuals is partially due to pilus antigenic variation. In addition, variation of the pilus has been proposed to function in the adaptation of the gonococcus to host environments. Previously, we described the development of a competitive reverse transcriptase (RT)-PCR assay that quantifies the frequency of pilin antigenic variation within a gonococcal population. Using this assay, the effect of different biologically relevant environmental conditions on the frequency of pilin antigenic variation was tested. Of the environmental conditions examined in vitro, only limited iron affected a significant change in the frequency of antigenic variation. Further investigation revealed that an observed increase in pilin antigenic variation reflected an increase in other DNA recombination and DNA repair processes within iron-starved cultures. In addition, this low iron-induced increase was determined to be independent of changes in RecA expression and was observed in a Fur mutant strain. As gonococci encounter conditions of low iron during infection, these data suggest that iron-limitation signals for increased recombinational events that are important for gonococcal pathogenesis. [source] Evaluation of wound healing activity of Lantana camara L. , a Preclinical studyPHYTOTHERAPY RESEARCH, Issue 2 2009B. Shivananda Nayak Abstract Lantana camara is used in herbal medicine for the treatment of skin itches, as an antiseptic for wounds, and externally for leprosy and scabies. The objective of our study was to investigate excision wound healing activity of the leaf extract of L. camara in rats. The animals were divided into two groups of 12 each in both the models. The test group animals were treated with the aqueous extract of L. camara (100 mg/kg/day) topically and the control group animals were left untreated. Wound healing efficacy was measured by determining the morphological and biochemical parameters. Wound healing time, wound contraction and synthesis of collagen were monitored periodically. Antimicrobial activities of the extract against the microorganisms were also assessed. Treatment of the wounds with extract enhanced significantly the rate of wound contraction (98%), synthesis of collagen and decreased mean wound healing time. These studies demonstrate that L. camara is effective in healing excision wounds in the experimental animal and could be evaluated as a therapeutic agent in tissue repair processes associated with skin injuries. Copyright © 2008 John Wiley & Sons, Ltd. [source] Effects of elevated ozone and low light on diurnal and seasonal carbon gain in sugar maplePLANT CELL & ENVIRONMENT, Issue 7 2001M. A. Topa Abstract The long-term interactive effects of ozone and light on whole-tree carbon balance of sugar maple (Acer saccharum Marsh.) seedlings were examined, with an emphasis on carbon acquisition, foliar partitioning into starch and soluble sugars, and allocation to growth. Sugar maple seedlings were fumigated with ambient, 1·7 × ambient and 3·0 × ambient ozone in open-top chambers for 3 years under low and high light (15 and 35% full sunlight, respectively). Three years of ozone fumigation reduced the total biomass of seedlings in the low- and high-light treatments by 64 and 41%, respectively, but had no effect on whole-plant biomass allocation. Ozone had no effect on net photosynthesis until late in the growing season, with low-light seedlings generally exhibiting more pronounced reductions in photosynthesis. The late-season reduction in photosynthesis was not due to impaired stomatal function, but was associated more with accelerated senescence or senescence-like injury. In contrast, the 3·0 × ambient ozone treatment immediately reduced diurnal starch accumulation in leaves by over 50% and increased partitioning of total non-structural carbohydrates into soluble sugars, suggesting that injury repair processes may be maintaining photosynthesis in late spring and early summer at the expense of storage carbon. The results in the present study indicate that changes in leaf-level photosynthesis may not accurately predict the growth response of sugar maple to ozone in different light environments. The larger reduction in seedling growth under low-light conditions suggests that seedlings in gap or closed-canopy environments are more susceptible to ozone than those in a clearing. Similarly, understanding the effects of tropospheric ozone on net carbon gain of a mature tree will require scaling of leaf-level responses to heterogeneous light environments, where some leaves may be more susceptible than others. [source] Structure of the endonuclease IV homologue from Thermotoga maritima in the presence of active-site divalent metal ionsACTA CRYSTALLOGRAPHICA SECTION F (ELECTRONIC), Issue 9 2010Stephen J. Tomanicek The most frequent lesion in DNA is at apurinic/apyrimidinic (AP) sites resulting from DNA-base losses. These AP-site lesions can stall DNA replication and lead to genome instability if left unrepaired. The AP endonucleases are an important class of enzymes that are involved in the repair of AP-site intermediates during damage-general DNA base-excision repair pathways. These enzymes hydrolytically cleave the 5,-phosphodiester bond at an AP site to generate a free 3,-hydroxyl group and a 5,-terminal sugar phosphate using their AP nuclease activity. Specifically, Thermotoga maritima endonuclease IV is a member of the second conserved AP endonuclease family that includes Escherichia coli endonuclease IV, which is the archetype of the AP endonuclease superfamily. In order to more fully characterize the AP endonuclease family of enzymes, two X-ray crystal structures of the T. maritima endonuclease IV homologue were determined in the presence of divalent metal ions bound in the active-site region. These structures of the T. maritima endonuclease IV homologue further revealed the use of the TIM-barrel fold and the trinuclear metal binding site as important highly conserved structural elements that are involved in DNA-binding and AP-site repair processes in the AP endonuclease superfamily. [source] Attenuation of Flightless I, an actin-remodelling protein, improves burn injury repair via modulation of transforming growth factor (TGF)-,1 and TGF-,3BRITISH JOURNAL OF DERMATOLOGY, Issue 2 2009D.H. Adams Summary Background, The pathophysiological mechanisms involved in burn injury repair are still not fully understood but include processes involving cellular proliferation, migration and adhesion. The actin cytoskeleton is intricately involved in these key wound repair processes. Flightless I (Flii), an actin-remodelling protein and transcriptional regulator, is an important regulator of wound healing. Objectives, To investigate the function of Flii gene expression in burn injury repair. Methods, Partial-thickness scald wounds were created on Flii heterozygous (Flii+/,), wild-type (WT) and Flii transgenic (FliiTg/+) mice. Burns were assessed using histology and immunohistochemistry, real-time quantitative polymerase chain reaction and biochemical analysis. Results, Flii expression, while upregulated in burn injuries, was significantly lower in the wounds of Flii+/, vs. WT vs. FliiTg/+ mice and healing was improved in Flii+/, mice with their burns healing faster than WT and FliiTg/+. Pro-scarring transforming growth factor (TGF)-,1 protein and gene expression were reduced in Flii+/, burns while antiscarring TGF-,3 was significantly elevated. Anti-,-smooth muscle actin (,-SMA) was decreased in Flii+/, burns suggesting a decrease in contractile myofibroblasts in the developing scars. Although Flii is primarily a nuclear and cytoplasmic protein it is also released by wounded cells. Intradermal injection of Flii-neutralizing antibodies (FliAbs) to WT burn wounds significantly improved their healing, indicating a potential novel approach for treating burns. Decreased TGF-,1 and elevated TGF-,3 expression were observed in FliAb-treated burns, which may contribute to their observed improvement in healing. Conclusions, Strategies aimed at reducing Flii expression, for example using neutralizing antibodies, may lead to improved burn outcomes. [source] | ||||||||||||||||||||||||||||