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Resorption Process (resorption + process)
Selected AbstractsRapidly progressive internal root resorption: a case reportDENTAL TRAUMATOLOGY, Issue 5 2008David Keinan Usually the process is asymptomatic and diagnosed upon routine radiographic examination. This case report presents a rapid progression of internal resorption related directly to traumatic injury. A 16-year-old female arrived at the emergency room after a mild extrusion of the mandibular incisors. The initial treatment included repositioning and splinting of the teeth. Radiographs performed at repositioning and splinting demonstrated normal configuration of the incisor's roots. Ten months later progressive internal resorption of the left mandibular first incisor was diagnosed. While treating this tooth similar process was detected in the right mandibular second incisor and in the mandibular left second incisor. The lower right first incisor reacted inconsistently to vitality test. As a result of the severe and rapidly progressive nature of the process, root canal treatments were performed in all lower incisors. The follow-up radiographs demonstrate arrest of the internal resorption process. [source] Matrix metalloproteinases mediate the dismantling of mesenchymal structures in the tadpole tail during thyroid hormone-induced tail resorptionDEVELOPMENTAL DYNAMICS, Issue 3 2002Jae-Chang Jung Abstract It has been suggested that a family of tissue remodelling enzymes called matrix metalloproteinases (MMPs) play a causal role in the process of tail resorption during thyroid hormone-induced metamorphosis of the anuran tadpole; however, this hypothesis has never been directly substantiated. We cloned two new Xenopus MMPs, gelatinase A (MMP-2) and MT3-MMP (MMP-16), and the MMP inhibitor TIMP-2. These clones were used along with several others to perform a comprehensive expression study. We show that all MMPs and TIMP-2 are dramatically induced in the resorbing tail during spontaneous metamorphosis and are spatially coexpressed, primarily in the remodelling mesenchymal tissues. By Northern blotting, we show that all the examined MMPs/TIMP-2 are also induced by treatment of organ-cultured tails with thyroid hormone (T3). Using the organ culture model, we provide the first direct evidence that MMPs are required for T3 -induced tail resorption by showing that a synthetic inhibitor of MMP activity/expression can specifically retard the resorption process. By gelatin zymography, we also show T3 induction of a fifth MMP, preliminarily identified as gelatinase B (GelB; MMP-9). Moreover, T3 not only induces MMP/TIMP expression but also MMP activation, and we provide evidence that TIMP-2 participates in the latter process. These findings suggest that MMPs and TIMPs act in concert to effect the dismantling of mesenchymal structures during T3 -induced metamorphic tadpole tail resorption. © 2002 Wiley-Liss, Inc. [source] Tissue alterations after tooth extraction with and without surgical trauma: a volumetric study in the beagle dogJOURNAL OF CLINICAL PERIODONTOLOGY, Issue 4 2008Stefan Fickl Abstract Objectives: The aim of this study is to evaluate whether tooth extraction without the elevation of a muco-periosteal flap has advantageous effects on the resorption rate after tooth extraction. Material and Methods: In five beagle dogs polyether impressions were taken before the surgery. The roots of the first and second pre-molars (P1 and P2) were extracted and the sites were assigned to one of the following treatments: treatment group (Tx) 1, no treatment; Tx 2, surgical trauma (flap elevation and repositioning); Tx 3, the extraction socket was filled with BioOss Collagen® and closed with a free soft-tissue graft; Tx 4, after flap elevation and repositioning, the extraction socket was treated with BioOss Collagen® and a free soft-tissue graft. Impressions were taken 2 and 4 months after surgery. The casts were scanned, matched together with baseline casts and evaluated with digital image analysis. Results: The "flapless groups" demonstrated significant lower resorption rates both when using socket-preservation techniques and without. Furthermore, socket-preservation techniques yielded better results compared with not treating the socket. Conclusion: The results demonstrate that leaving the periosteum in place decreases the resorption rate of the extraction socket. Furthermore, the treatment of the extraction socket with BioOss Collagen® and a free gingival graft seems beneficial in limiting the resorption process after tooth extraction. [source] Acid Phosphatase Activity May Affect the Tuber Swelling by Partially Regulating Sucrose-mediated Sugar Resorption in PotatoJOURNAL OF INTEGRATIVE PLANT BIOLOGY, Issue 6 2008Da-Yong Wang Abstract APase activity is involved in regulating many physiological and developmental events by affecting the resorption process. In this study, we investigate the role of APase activity in tuber development in potato. APase activities were mainly localized in cytoplasm, gaps among cells and stroma of amyloplasts of parenchyma cells at the stage of tuber swelling. AP1, encoding a putative APase, was also highly expressed in swelling tubers and a low level of expression was observed in elongated stolons and matured tubers. Inhibition of APase activity by applying Brefeldin A, an inhibitor of APase production and secretion, significantly suppressed the tuber swelling and moderately affected the stolon elongation and the tuberization frequency. During tuber development, sucrose serves as the main soluble sugar for long-distance transportation and resorption. Moreover, inhibition of APase activity by Brefeldin A markedly reduced the sucrose content in tubers and further decreased the starch accumulation, suggesting that the function of APase in regulating the tuber swelling might be at least partially mediated by the sugar resorption. Exogenous sucrose treatments further indicate the important role of sucrose-mediated sugar resorption in tuber swelling. These results suggest that the APase activity might affect the tuber swelling by partially regulating the sucrose-mediated sugar resorption. [source] On the mechanism of resorption zoning in metamorphic garnetJOURNAL OF METAMORPHIC GEOLOGY, Issue 8 2003S. L. Hwang Abstract An analytical electron microscope study of almandine garnet from a metamorphosed Al,Fe-rich rock revealed detailed composition profiles and defect microstructures of resorption zoning along fluid-infiltrated veins and even into the garnet/ilmenite (inclusion) interface. This indicates a limited volume diffusion for the cations in substitution (mainly Ca and Fe) and an interface-controlled partition for the extension of a composition-invariant margin. A corrugated interface between the Ca-rich margin/zone and the almandine garnet core is characterized by dislocation arrays and recovery texture further suggesting a resorption process facilitated by diffusion-induced recrystallization, diffusion-induced dislocation migration and diffusion,induced grain boundary migration. Integrated microstructural and chemical studies are essential for understanding the underlying mechanisms of processes such as garnet zoning and its modification. Without this understanding, it will not be possible to reliably use garnet compositions for thermobarometry and other applications that rely on garnet chemical information. [source] TNF-,,induced NF-,B signaling reverses age-related declines in VEGF induction and angiogenic activity in intervertebral disc tissuesJOURNAL OF ORTHOPAEDIC RESEARCH, Issue 2 2009Tetsuro Ohba Abstract We previously demonstrated that VEGF and its receptors were expressed in human herniated discs (HD). TNF-, induced VEGF, resulting in neovascularization of disc tissues in a model of HD. The goal of the current research was to investigate the precise role of TNF-,,induced VEGF and the mechanism of angiogenesis in disc tissues. We performed ELISAs, Western blots, and immunohistological examinations to assess the role of TNF-,,induced VEGF using organ disc cultures with wild type, TNF receptor 1-null (TNF-RInull), or TNF receptor 2-null (TNF-RIInull) mice. VEGF induction was inhibited when we used TNF-RInull -derived disc tissues. NF-,B pathway inhibitors also strongly suppressed VEGF induction. Thus, TNF-, induced VEGF expression in disc cells primarily through the NF-,B pathway. In addition, VEGF immunoreactivity was detected predominantly in annulus fibrosus cells and increased after TNF-, stimulation. TNF-, treatment also resulted in CD31 expression on endothelial cells and formation of an anastomosing network. In contrast, angiogenic activity was strongly inhibited in the presence of NF-,B inhibitors or anti-VEGF antibody. Our data show angiogenesis activity in disc tissues is regulated by VEGF and the NF-,B pathway, both of which are induced by TNF-,. The level of angiogenic activity in disc tissues was closely related to aging. Because neovascularization of HD is indispensable for HD resorption, the prognosis of HD and the rate of the resorption process in patients may vary as a function of the patient's age. © 2008 Orthopaedic Research Society. Published by Wiley Periodicals, Inc. J Orthop Res 27:229,235, 2009 [source] Back-scattered electron imaging and elemental microanalysis of retrieved bone tissue following maxillary sinus floor augmentation with calcium sulphateCLINICAL ORAL IMPLANTS RESEARCH, Issue 8 2008Nicola Slater Abstract Objectives: To investigate the presence and composition of residual bone graft substitute material in bone biopsies from the maxillary sinus of human subjects, following augmentation with calcium sulphate (CaS). Material and methods: Bone cores were harvested from the maxillary sinus of patients who had undergone a sinus lift procedure using CaS G170 granules 4 months after the initial surgery. Samples from seven patients, which contained residual biomaterial particles, were examined by field emission scanning electron microscopy and energy dispersive X-ray spectroscopy was used to determine the composition of the remaining bone graft substitute material. Results: Residual graft material occurred in isolated areas surrounded by bone and consisted of individual particles up to 1 mm in length and smaller spherical granules. On the basis of 187 separate point analyses, the residual material was divided into three categories (A, B and C) consisting of: A, mainly CaS (S/P atomic% ratio ,2.41); B, a heterogeneous mixture of CaS and calcium phosphate (S/P=0.11,2.4) and C, mainly calcium phosphate (S/P,0.11; C), which had a mean Ca : P ratio of 1.63±0.2, consistent with Ca-deficient hydroxyapatite. Linescans and elemental maps showed that type C material was present in areas which appeared dense and surrounded, or were adjacent to, more granular CaS-containing material, and also occurred as spherical particles. The latter could be disintegrating calcium phosphate in the final stages of the resorption process. Conclusions: CaS resorption in the human maxillary sinus is accompanied by CaP precipitation which may contribute to its biocompatibility and rapid replacement by bone. [source] Spatial Distribution of Bax and Bcl-2 in Osteocytes After Bone Fatigue: Complementary Roles in Bone Remodeling Regulation?,JOURNAL OF BONE AND MINERAL RESEARCH, Issue 5 2002Olivier Verborgt Abstract Osteocyte apoptosis appears to play a key role in the mechanism by which osteoclastic resorption activity targets bone for removal, because osteocyte apoptosis occurs in highly specific association with microdamage and subsequent remodeling after fatigue. However, beyond terminal deoxynucleotidyl transferase (TdT)-mediated deoxyuridine triphosphate (dUTP)-biotin nick end labeling (TUNEL) assay, little is known about the mechanisms controlling osteocyte apoptosis in vivo. In the current studies, expression of Bax, a proapoptotic gene product, and Bcl-2, an antiapoptotic gene product, was determined in osteocytes of fatigued rat bone using immunocytochemical staining and compared with TUNEL staining patterns. Bax and Bcl-2 were evident in osteocytes by 6 h after loading. Moreover, Bax and Bcl-2 in osteocytes were expressed differently as a function of distance from microdamage sites. The peak of Bax expression and TUNEL+ staining in osteocytes was observed immediately at the microcrack locus, which is where bone resorption occurs in this system; in contrast, Bcl-2 expression, the antiapoptotic signal, reached its greatest level at some distance (1-2 mm) from microcracks. These data suggest that near sites of microinjury in bone, those osteocytes that do not undergo apoptosis are prevented from doing so by active protection mechanisms. Moreover, the zone of apoptotic osteocytes around microcracks was effectively "walled in" by a surrounding halo of surviving osteocytes actively expressing Bcl-2. Thus, the expression pattern of apoptosis-inhibiting gene products by osteocytes surrounding the apoptotic osteocyte at microdamage sites also may provide important signals in the guidance of resorption processes that occur in association with osteocyte apoptosis after fatigue. [source] | |||||||||||||