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Deep Zones (deep + zone)
Selected AbstractsThe Art of Repair in Surgical Hair Restoration,Part II: The Tactics of RepairDERMATOLOGIC SURGERY, Issue 10 2002Robert M. Bernstein MD background. As patient awareness of new hair transplantation techniques grows, the repair of improperly planned or poorly executed procedures becomes an increasingly important part of surgical hair restoration. objective. Part II of this series is written to serve as a practical guide for surgeons who perform repairs in their daily practices. It focuses on specific repair techniques. methods. The repairs are performed by excision with reimplantation and/or by camouflage. Follicular unit transplantation is used for the restorative aspects of the procedure. results. Using punch or linear excision techniques allows the surgeon to relocate poorly planted grafts to areas that are more appropriate. The key elements of camouflage include creating a deep zone of follicular units, angling grafts in their natural direction, and using forward and side weighting of grafts to increase the appearance of fullness. In special situations, removal of grafts without reimplantation can be accomplished using lasers or electrolysis. conclusion. Meticulous surgical techniques and optimal utilization of a limited hair supply will enable the surgeon to achieve the best possible cosmetic results for patients requiring repairs. [source] The Art of Repair in Surgical Hair Restoration Part I: Basic Repair StrategiesDERMATOLOGIC SURGERY, Issue 9 2002Robert M. Bernstein MD background. An increasingly important part of many hair restoration practices is the correction of hair transplants that were performed using older, outdated methods, or the correction of hair transplants that have left disfiguring results. The skill and judgment involved in these repair procedures often exceed those needed to operate on patients who have had no prior surgery. The use of small grafts alone does not protect the patient from poor work. Errors in surgical and aesthetic judgment, performing procedures on noncandidate patients, and the failure to communicate successfully with patients about realistic expectations remain major problems. objective. This two-part series presents new insights into repair strategies and expands upon several techniques previously described in the hair restoration literature. The focus is on creative aesthetic solutions to solve the supply/demand limitations inherent in most repairs. This article is written to serve as a guide for surgeons who perform repairs in their daily practices. methods. The repairs are performed by excision with reimplantation and/or by camouflage. Follicular unit transplantation is used for the restorative aspects of the procedure. results. Using punch or linear excision techniques allows the surgeon to relocate poorly planted grafts to areas that are more appropriate. In special situations, removal of grafts without reimplantation can be accomplished using lasers or electrolysis. The key elements of camouflage include creating a deep zone of follicular units, angling grafts in their natural direction, and using forward and side weighting of grafts to increase the appearance of fullness. The available donor supply is limited by hair density, scalp laxity, and scar placement. conclusion. Presented with significant cosmetic problems and severely limited donor reserves, the surgeon performing restorative hair transplantation work faces distinct challenges. Meticulous surgical techniques and optimal utilization of a limited hair supply will enable the surgeon to achieve the best possible cosmetic results for patients requiring repairs. [source] Synthesis of insulin-like growth factor binding protein 3 in vitro in human articular cartilage culturesARTHRITIS & RHEUMATISM, Issue 2 2003Tamar Eviatar Objective To quantify the rate of synthesis of insulin-like growth factor binding protein 3 (IGFBP-3) and insulin-like growth factor 1 (IGF-1) by in vitro cultures of normal and osteoarthritic (OA) human articular cartilage. Methods Levels of IGF-1 and IGFBP-3 in media from in vitro cultures of human cartilage were determined by radioimmunoassay (RIA). IGFBPs were characterized by immunoblots and ligand blots. Ultrafiltration and RIA analysis of synovial fluid (SF) samples and washings of cartilage samples ex vivo were used to calculate partition coefficients and to estimate the amount of IGF-1 and IGFBP-3 in cartilage in vivo. Results OA cartilage synthesized 150 ng of IGFBP-3 per gm of cartilage per day, compared with 50 ng synthesized by normal cartilage. The surface zone of normal cartilage produced more IGFBP-3 than did the deep zone. Immunoblots and ligand blots confirmed the presence of IGFBP-3. IGFBP-3 synthesis was stimulated by exogenous IGF-1. No freshly synthesized IGF-1 was detected. The quantities of IGF-1 and IGFBP-3 present ex vivo were 11.3 and 78.7 ng/gm of cartilage in normal cartilage and 21.6 and 225.4 ng/gm in OA cartilage. Conclusion The results show that while IGFBP-3 is synthesized in explant cultures, IGF-1 is not. The rate of IGFBP-3 synthesis is 3 times higher in OA than in normal cartilage. Both IGFBP-3 and IGF-1 penetrate into cartilage from SF in vivo. We estimate that the quantities of IGFBP-3 produced in culture by human cartilage are small compared with the amount supplied in the form of "small complexes" from the circulation. The high value of the partition coefficient of IGFBP-3 implies binding to the matrix. [source] Collagen architecture and failure processes in bovine patellar cartilageJOURNAL OF ANATOMY, Issue 4 2001JACK L. LEWIS Cartilage fails by fibrillation and wearing away. This study was designed to identify the microscopic failure processes in the collagen network of bovine cartilage using scanning electron microscopy. Cartilage samples from fibrillated cartilage from the bovine patella were removed from the bone, fixed, digested to remove proteoglycans, freeze-fractured, and processed for SEM. The architecture of the collagen network in the normal cartilage was first defined, and then the failure processes were identified by examining sites of fibrillation and at crack tips. The bovine patellar cartilage was organised with a superficial layer composed of 3,5 lamina, attached to a sub-superficial tissue by angled bridging fibrils. Collagen in the sub-superficial tissue was organised in lamina oriented in the radial direction up to the transition zone. Failure of the system occurred by cracks forming in superficial layer and lamina, creating flaps of lamina that rolled up into the larger ,fronds'. Larger cracks not following the laminar planes occurred in the transition, mid, and deep zones. Failure at the crack tips in the sub-superficial tissue appeared to be by peeling of collagen fibrils, as opposed to breaking of collagen fibrils, suggesting a ,glue' bonding the collagen fibrils in a parallel fashion. Cracks propagated by breaking these bonds. This bond could be a site of disease action, since weakening of the bond would accelerate crack propagation. [source] Localization of insulin-like growth factor binding protein-2 in chondrocytes of bovine articular cartilageJOURNAL OF ORTHOPAEDIC RESEARCH, Issue 2 2003Teresa I. Morales Purpose: Previous work indicated that transforming growth factor (TGF-,) treatment of bovine articular cartilage resulted in an accumulation of insulin-like growth factor binding protein-2 (IGF-BP-2). The purpose of the work presented in this paper was to define the localization of the IGF-BP-2 in freshly excised articular cartilage and in slices cultured in the presence and absence of TGF-,. Method: Newborn calf articular cartilage was dissected and immediately fixed or maintained in organ culture for five days under basal conditions (media without added serum or growth factors) or with basal media containing 15 ng/ml of TGF-,1. Frozen or paraffin embedded sections were prepared, and immunohistochemistry using anti-IGF-BP-2 performed. Results: The paraffin sections provided the best preservation of morphology and consistency of immunohistochemical staining patterns. In fresh cartilage slices, IGF-BP-2 was associated with most of the chondrocytes. The basal cultured cartilage showed positive immunostaining in some areas, but not others: the most consistently stained area was the upper radial zone. In all cases where a positive reaction was observed, it was associated mostly with chondrocytes. On the other hand, all the TGF-, treated samples that were examined in this study were evenly stained, and most chondrocytes were positive in all areas from superficial to deep zones, thus closely resembling the pattern of fresh tissue. Conclusions: It is concluded that IGF-BP-2 is closely cell associated in bovine articular cartilage. Following culture of cartilage slices, TGF-, increases the number of cells with positive immunostaining. These data help to support the postulate that TGF-, exerts at least some of its actions in articular cartilage via cross-talk mechanisms involving the IGF-BP-2 system. © 2002 Orthopaedic Research Society. Published by Elsevier Science Ltd. All rights reserved. [source] Induction of a neoarthrosis by precisely controlled motion in an experimental mid-femoral defectJOURNAL OF ORTHOPAEDIC RESEARCH, Issue 3 2002Dennis M. Cullinane Bone regeneration during fracture healing has been demonstrated repeatedly, yet the regeneration of articular cartilage and joints has not yet been achieved. It has been recognized however that the mechanical environment during fracture healing can be correlated to the contributions of either the endochondral or intramembranous processes of bone formation, and to resultant tissue architecture. Using this information, the goal of this study was to test the hypothesis that induced motion can directly regulate osteogenic and chondrogenic tissue formation in a rat mid-femoral bone defect and thereby influence the anatomical result. Sixteen male Sprague Dawley rats (400 ± 20 g) underwent production of a mid-diaphyseal, non-critical sized 3.0 mm segmental femoral defect with rigid external fixation using a custom designed four pin fixator. One group of eight animals represented the controls and underwent surgery and constant rigid fixation. In the treatment group the custom external fixator was used to introduce daily interfragmentary bending strain in the eight treatment animals (12°s angular excursion), with a hypothetical symmetrical bending load centered within the gap. The eight animals in the treatment group received motion at 1.0 Hz, for 10 min a day, with a 3 days on, one day off loading protocol for the first two weeks, and 2 days on, one day off for the remaining three weeks. Data collection included histological and immunohistological identification of tissue types, and mean collagen fiber angles and angular conformity between individual fibers in superficial, intermediate, and deep zones within the cartilage. These parameters were compared between the treatment group, rat knee articular cartilage, and the control group as a structural outcome assessment. After 35 days the control animals demonstrated varying degrees of osseous union of the defect with some animals showing partial union. In every individual within the mechanical treatment group the defect completely failed to unite. Bony arcades developed in the experimental group, capping the termini of the bone segments on both sides of the defect in four out of six animals completing the study. These new structures were typically covered with cartilage, as identified by specific histological staining for Type II collagen and proteoglycans. The distribution of collagen within analogous superficial, intermediate, and deep zones of the newly formed cartilage tissue demonstrated preferred fiber angles consistent with those seen in articular cartilage. Although not resulting in complete joint development, these neoarthroses show that the induced motion selectively controlled the formation of cartilage and bone during fracture repair, and that it can be specifically directed. They further demonstrate that the spatial organization of molecular components within the newly formed tissue, at both microanatomical and gross levels, are influenced by their local mechanical environment, confirming previous theoretical models. © 2002 Orthopaedic Research Society. Published by Elsevier Science Ltd. All rights reserved. [source] First assessment of methane and carbon dioxide emissions from shallow and deep zones of boreal reservoirs upon ice break-upLAKES & RESERVOIRS: RESEARCH AND MANAGEMENT, Issue 1 2006Éric Duchemin Abstract Most studies dealing with greenhouse gas (GHG) emissions from large boreal reservoirs were conducted during the ice-free period. In this paper, the potential methane (CH4) and carbon dioxide emissions are estimated for two hydroelectric reservoirs, as well as for a small experimental reservoir from boreal latitudes (northern Quebec, Canada) at the ice break-up event through diffusion (diffusive fluxes) and release of bubbles (bubbling fluxes). The results of this preliminary study suggest that the winter diffusive fluxes at the air,water interface of the sampled reservoirs represent < 7% of their cumulative carbon emissions during the ice-free period. Furthermore, the release upon ice-break of CH4 bubbles accumulated under the ice cover during the winter could represent 2% of the summer carbon emissions from hydroelectric reservoirs in northern Quebec. The results presented herein suggest that the GHG emissions upon ice break-up from the boreal reservoirs investigated are a small, but non-negligible, component of their annual GHG emissions. [source] Profiling microRNA expression in bovine articular cartilage and implications for mechanotransductionARTHRITIS & RHEUMATISM, Issue 8 2009Walter Dunn Objective Articular cartilage is an avascular tissue with precise polarity and organization comprising 3 distinct functional zones: the surface, middle, and deep zones. Each zone has a different gene expression pattern that plays a specific role in articular cartilage development and maintenance. MicroRNA (miRNA) are small noncoding gene products that play an important regulatory role in determining cell differentiation and function. The purpose of this study was to test our hypothesis that miRNA expression profiles in the different articular cartilage zones as well as between regions subjected to different levels of weight-bearing stresses are unique. Methods Using an miRNA microarray approach in conjunction with quantitative reverse transcription,polymerase chain reaction, we identified miRNA in bovine articular cartilage that were differentially expressed in the different functional zones and in the anterior weight-bearing and posterior non,weight-bearing regions of the medial femoral condyle (M1 and M4, respectively). Results We identified miRNA-221 and miR-222 as part of a subset of differentially expressed miRNA that were up-regulated in articular cartilage in the anterior, M1, greater weight-bearing location. Additionally, miR-126, miR-145, and miR-335 were down-regulated in monolayers of tissue-cultured chondrocytes as compared with levels determined directly from intact native cartilage. Conclusion In conclusion, miR-222 expression patterns in articular cartilage are higher in the weight-bearing anterior medial condyle as compared with the posterior non,weight-bearing medial condyle. Thus, miR-222 might be a potential regulator of an articular cartilage mechanotransduction pathway. These data implicate miRNA in the maintenance of articular cartilage homeostasis and are therefore targets for articular cartilage tissue engineering and regenerative medicine. [source] | |||||||||||||