Management of segmental bony defects: the role of osteoconductive orthobiologics.

PubMed

McKee, Michael D

2006-01-01

Our knowledge about, and the availability of, orthobiologic materials has increased exponentially in the last decade. Although previously confined to the experimental or animal-model realm, several orthobiologics have been shown to be useful in a variety of clinical situations. As surgical techniques in vascular anastomosis, soft-tissue coverage, limb salvage, and fracture stabilization have improved, the size and frequency of bony defects (commensurate with the severity of the initial injury) have increased, as well. Because all methods of managing segmental bony defects have drawbacks, a need remains for a readily available, void-filling, inexpensive bone substitute. Such a bone substitute fulfills a permissive role in allowing new bone to grow into a given defect. Such potential osteoconductive materials include ceramics, calcium sulfate or calcium phosphate compounds, hydroxyapatite, deproteinized bone, corals, and recently developed polymers. Some materials that have osteoinductive properties, such as demineralized bone matrix, also display prominent osteoconductive properties.

Custom-made composite scaffolds for segmental defect repair in long bones.

PubMed

Reichert, Johannes C; Wullschleger, Martin E; Cipitria, Amaia; Lienau, Jasmin; Cheng, Tan K; Schütz, Michael A; Duda, Georg N; Nöth, Ulrich; Eulert, Jochen; Hutmacher, Dietmar W

2011-08-01

Current approaches for segmental bone defect reconstruction are restricted to autografts and allografts which possess osteoconductive, osteoinductive and osteogenic properties, but face significant disadvantages. The objective of this study was to compare the regenerative potential of scaffolds with different material composition but similar mechanical properties to autologous bone graft from the iliac crest in an ovine segmental defect model. After 12 weeks, in vivo specimens were analysed by X-ray imaging, torsion testing, micro-computed tomography and histology to assess amount, strength and structure of the newly formed bone. The highest amounts of bone neoformation with highest torsional moment values were observed in the autograft group and the lowest in the medical grade polycaprolactone and tricalcium phosphate composite group. The study results suggest that scaffolds based on aliphatic polyesters and ceramics, which are considered biologically inactive materials, induce only limited new bone formation but could be an equivalent alternative to autologous bone when combined with a biologically active stimulus such as bone morphogenetic proteins.

Washout of ⁸²Rb as a marker of impaired tissue integrity, obtained by list-mode cardiac PET/CT: relationship with perfusion/metabolism patterns of myocardial viability.

PubMed

Chien, David T; Bravo, Paco; Higuchi, Takahiro; Merrill, Jennifer; Bengel, Frank M

2011-08-01

Myocardial washout of the potassium analogue (82)Rb may indicate tissue impairment. Few studies have evaluated its usefulness for viability assessment, and controversial results were reported. We revisited this topic using list-mode positron emission tomography (PET)/CT. A total of 22 patients with chronic ischemic cardiomyopathy (ICM) and 11 control subjects with normal CT coronary angiogram were studied. Rest (82)Rb PET/CT studies were acquired in list mode and resampled to static, gated, and dynamic images. Using a 17-segment model, (82)Rb washout was determined by monoexponential fitting of myocardial time-activity curves. In ICM patients, (18)F-fluorodeoxyglucose (FDG) studies were obtained in the same session and segments were classified as normally perfused, mismatch, or matched defect. (82)Rb washout was minimal and homogeneous in control subjects. Normally perfused segments of ICM did not differ (p = 0.33). ICM patients had a left ventricular ejection fraction (LVEF) of 25 ± 12%, 25/353 mismatched, and 46/353 matched defect segments. (82)Rb washout was higher in hypoperfused vs normal segments (p < 0.05), but not different between mismatch and matched defect (p = 0.18). Intraindividual analysis in nine patients showing both FDG mismatch and matched defect confirmed absence of differences. Overall, segmental (82)Rb washout correlated inversely with (82)Rb uptake (r = -0.70; p < 0.05) and less well with FDG uptake (r = -0.31; p < 0.05). Using state-of-the-art PET/CT technology for myocardial viability assessment, (82)Rb washout does not distinguish between perfusion/metabolism patterns of hibernating myocardium and scar. Tissue integrity may be at least partially impaired in hibernation.

Repair of Segmental Bone Defect Using Totally Vitalized Tissue Engineered Bone Graft by a Combined Perfusion Seeding and Culture System

PubMed Central

Feng, Ya-Fei; Li, Xiang; Hu, Yun-Yu; Wang, Zhen; Ma, Zhen-Sheng; Lei, Wei

2014-01-01

Background The basic strategy to construct tissue engineered bone graft (TEBG) is to combine osteoblastic cells with three dimensional (3D) scaffold. Based on this strategy, we proposed the “Totally Vitalized TEBG” (TV-TEBG) which was characterized by abundant and homogenously distributed cells with enhanced cell proliferation and differentiation and further investigated its biological performance in repairing segmental bone defect. Methods In this study, we constructed the TV-TEBG with the combination of customized flow perfusion seeding/culture system and β-tricalcium phosphate (β-TCP) scaffold fabricated by Rapid Prototyping (RP) technique. We systemically compared three kinds of TEBG constructed by perfusion seeding and perfusion culture (PSPC) method, static seeding and perfusion culture (SSPC) method, and static seeding and static culture (SSSC) method for their in vitro performance and bone defect healing efficacy with a rabbit model. Results Our study has demonstrated that TEBG constructed by PSPC method exhibited better biological properties with higher daily D-glucose consumption, increased cell proliferation and differentiation, and better cell distribution, indicating the successful construction of TV-TEBG. After implanted into rabbit radius defects for 12 weeks, PSPC group exerted higher X-ray score close to autograft, much greater mechanical property evidenced by the biomechanical testing and significantly higher new bone formation as shown by histological analysis compared with the other two groups, and eventually obtained favorable healing efficacy of the segmental bone defect that was the closest to autograft transplantation. Conclusion This study demonstrated the feasibility of TV-TEBG construction with combination of perfusion seeding, perfusion culture and RP technique which exerted excellent biological properties. The application of TV-TEBG may become a preferred candidate for segmental bone defect repair in orthopedic and maxillofacial fields. PMID:24728277

Use of Adipose Derived Stem Cells to Treat Large Bone Defects. Addendum

DTIC Science & Technology

2009-07-01

optimal delivery . We have also completed characterization of our segmental defect model, including analysis of vascular ingrowth during defect healing...cells seeded in 1.2% Keltone alginate at a density of 12-15x106cells/ml were loaded on 24-well transwell insert membranes [6]. Once hydrogel discs...process from tissue culture plates and hydrogels does not alter the surface phenotype. Gene expression of surface markers and proteins associated with

Preliminary evaluation of a load-bearing BMP-2 carrier for segmental defect regeneration.

PubMed

Chu, Tien-Min G; Sargent, Peter; Warden, Stuart J; Turner, Charles H; Stewart, Rena L

2006-01-01

Large segmental defects in bones can result from tumor removal, massive trauma, congenital malformation, or non-union fractures. Such defects often are difficult to manage and require multiple-phase surgery to achieve adequate union and function. In this study, we propose a novel design of bone morphogenetic protein 2 (BMP-2) carrier for tissue engineering of segmental defect regeneration. The tube-shaped BMP-2 carrier was fabrication from a poly(propylene fumarate)/tricalcium phosphate (PPF/TCP) composite via casting technique developed in our laboratory. An in vitro evaluation showed that the compressive strength of the carrier decreased about 48% in 12 weeks while maintained a pH in the 6.8-7.4 range. In vivo study was conducted by implanting carriers loaded with 10 microg of BMP-2 in 5 mm rat femur gap model for 15 weeks. X-ray evidence of bridging was first found in the BMP group at 3 weeks. Bridging in all animals (N = 4) in the BMP group was found at 9 weeks. No x-ray evidence of bridging was found in the No BMP group (N = 3). pQCT analysis indicated that the bone mineral density of the callus in the BMP group has reached the level of native femur at 15 weeks after implantation, while the callus in the No BMP group has a bone mineral density at a lower level of 84% to the native femur. Histology analysis shows that a normal fatty bone marrow was restored and mineralized callus formed and bridged the segmental defect.

Optimization of Soft Tissue Management, Spacer Design, and Grafting Strategies for Large Segmental Bone Defects using the Chronic Caprine Tibial Defect Model

DTIC Science & Technology

2014-10-01

histology, and microCT analysis. In the current phase of work he will receive more specialized ` training and orientation to microCT analysis...fibrous connective tissue. • Performed histology on goat autogenous bone graft which demonstrated that the quantity and quality of cancellous bone graft

Three-dimensional model simulation and reconstruction of composite total maxillectomy defects with fibula osteomyocutaneous flap flow-through from radial forearm flap.

PubMed

He, Yue; Zhu, Han Guang; Zhang, Zhi Yuan; He, Jie; Sader, Robert

2009-12-01

A total maxillectomy always causes composite defects of maxilla, zygomatic bone, orbital floor or rim, and palatal and nasal mucosa lining. This leads to significant functional and cosmetic consequences after ablative surgery. The purpose of this clinical study was to preliminarily 3-dimensionally reconstruct the defect of total maxillectomy with sufficient bone support and soft tissue lining. Three-dimensional model simulation technique and free fibula osteomyocutaneous flap flow-through from radial forearm flap were used to reconstruct a total maxillectomy defect for a 21-year-old female patient. Preoperatively, the 3-dimensional (3D) simulated resin models of skeleton and fibula were used to design the osteotomies and bone segment replacement. At surgery, a 22-cm-length free fibula was divided into 4 segments to make 1 maxilla skeletal framework in the schedule of the preoperative model surgical planning with a radial forearm flap flow-through for the free fibula flap with skin paddle to repair the palatal and nasal region. Free fibula and radial forearm flap were alive, and the patient was satisfied with the results both esthetically and functionally after dental rehabilitation which was carried out 6 months after surgery. This preliminarily clinical study and case demonstrated that: the fibula osteomyocutaneous flap is an ideal donor site in 3D total maxillectomy defect reconstruction, because of its thickness, length, and bone uniformity which makes ideal support for dental rehabilitation; the flow-through forearm radial flap not only serves as the vascular bridge to midface reconstruction, but also provides sufficient soft tissue cover for the intraoral defect; and the 3D model simulation and preoperative surgical planning are effective methods to refine reconstruction surgery, shorten the surgical time, and predict the outcome after operation.

Optimization of Soft Tissue Management, Spacer Design, and Grafting Strategies for Large Segmental Bone Defects using the Chronic Caprine Tibial Defect Model

DTIC Science & Technology

2016-12-01

gastrocnemius muscles. 4. Place an interlocking intramedullary nail using a custom spacer to maintain 5-cm defect length. 5. Place a pre-molded 5 cm long x...2 cm diameter PMMA spacer around the nail in the defect. 6. Irrigate the wound with normal (0.9 %) saline and close the wound. The Treatment...PMMA spacer using a “bomb bay door opening”. 4. Remove the spacer without damaging the membrane or nail . 5. Collect appropriate IM samples as

Relation between lung perfusion defects and intravascular clots in acute pulmonary thromboembolism: assessment with breath-hold SPECT-CT pulmonary angiography fusion images.

PubMed

Suga, Kazuyoshi; Yasuhiko, Kawakami; Iwanaga, Hideyuki; Tokuda, Osamu; Matsunaga, Naofumi

2008-09-01

The relation between lung perfusion defects and intravascular clots in acute pulmonary thromboembolism (PTE) was comprehensively assessed on deep-inspiratory breath-hold (DIBrH) perfusion SPECT-computed tomographic pulmonary angiography (CTPA) fusion images. Subjects were 34 acute PTE patients, who had successfully performed DIBrH perfusion SPECT using a dual-headed SPECT and a respiratory tracking system. Automated DIBrH SPECT-CTPA fusion images were used to assess the relation between lung perfusion defects and intravascular clots detected by CTPA. DIBrH SPECT visualized 175 lobar/segmental or subsegmental defects in 34 patients, and CTPA visualized 61 intravascular clots at variable locations in 30 (88%) patients, but no clots in four (12%) patients. In 30 patients with clots, the fusion images confirmed that 69 (41%) perfusion defects (20 segmental, 45 subsegmental and 4 lobar defects) of total 166 defects were located in lung territories without clots, although the remaining 97 (58%) defects were located in lung territories with clots. Perfusion defect was absent in lung territories with clots (one lobar branch and three segmental branches) in four (12%) of these patients. In four patients without clots, nine perfusion defects including four segmental ones were present. Because of unexpected dissociation between intravascular clots and lung perfusion defects, the present fusion images will be a useful adjunct to CTPA in the diagnosis of acute PTE.

Computer aided weld defect delineation using statistical parametric active contours in radiographic inspection.

PubMed

Goumeidane, Aicha Baya; Nacereddine, Nafaa; Khamadja, Mohammed

2015-01-01

A perfect knowledge of a defect shape is determinant for the analysis step in automatic radiographic inspection. Image segmentation is carried out on radiographic images and extract defects indications. This paper deals with weld defect delineation in radiographic images. The proposed method is based on a new statistics-based explicit active contour. An association of local and global modeling of the image pixels intensities is used to push the model to the desired boundaries. Furthermore, other strategies are proposed to accelerate its evolution and make the convergence speed depending only on the defect size as selecting a band around the active contour curve. The experimental results are very promising, since experiments on synthetic and radiographic images show the ability of the proposed model to extract a piece-wise homogenous object from very inhomogeneous background, even in a bad quality image.

[Three-dimensional finite element analysis of three conjunctive methods of free iliac bone graft for established mandibular body defects].

PubMed

Wang, Dong; Yang, Zhuang-qun; Hu, Xiao-yi

2007-08-01

To analyze the stress and displacement distribution of 3D-FE models in three conjunctive methods of vascularized iliac bone graft for established mandibular body defects. Using computer image process technique, a series of spiral CT images were put into Ansys preprocess programe to establish three 3D-FE models of different conjunctions. The three 3D-FE models of established mandibular body defects by vascularized iliac bone graft were built up. The distribution of Von Mises stress and displacement around mandibular segment, grafted ilium, plates and screws was obtained. It may be determined successfully that the optimal conjunctive shape be the on-lay conjunction.

Comparison of the sensitivity and specificity of 5 image sets of dual-energy computed tomography for detecting first-pass myocardial perfusion defects compared with positron emission tomography.

PubMed

Li, Wenhuan; Zhu, Xiaolian; Li, Jing; Peng, Cheng; Chen, Nan; Qi, Zhigang; Yang, Qi; Gao, Yan; Zhao, Yang; Sun, Kai; Li, Kuncheng

2014-12-01

The sensitivity and specificity of 5 different image sets of dual-energy computed tomography (DECT) for the detection of first-pass myocardial perfusion defects have not systematically been compared using positron emission tomography (PET) as a reference standard. Forty-nine consecutive patients, with known or strongly suspected of coronary artery disease, were prospectively enrolled in our study. Cardiac DECT was performed at rest state using a second-generation 128-slice dual-source CT. The DECT data were reconstructed to iodine maps, monoenergetic images, 100 kV images, nonlinearly blended images, and linearly blended images by different postprocessing techniques. The myocardial perfusion defects on DECT images were visually assessed by 5 observers, using standard 17-segment model. Diagnostic accuracy of 5 image sets was assessed using nitrogen-13 ammonia PET as the gold standard. Discrimination was quantified using the area under the receiver operating characteristic curve (AUC), and AUCs were compared using the method of DeLong. The DECT and PET examinations were successfully completed in 30 patients and a total of 90 territories and 510 segments were analyzed. Cardiac PET revealed myocardial perfusion defects in 56 territories (62%) and 209 segments (41%). The AUC of iodine maps, monoenergetic images, 100 kV images, nonlinearly blended images, and linearly blended images were 0.986, 0.934, 0.913, 0.881, and 0.871, respectively, on a per-territory basis. These values were 0.922, 0.813, 0.779, 0.763, and 0.728, respectively, on a per-segment basis. DECT iodine maps shows high sensitivity and specificity, and is superior to other DECT image sets for the detection of myocardial perfusion defects in the first-pass myocardial perfusion.

In-situ tissue regeneration through SDF-1α driven cell recruitment and stiffness-mediated bone regeneration in a critical-sized segmental femoral defect.

PubMed

Cipitria, Amaia; Boettcher, Kathrin; Schoenhals, Sophia; Garske, Daniela S; Schmidt-Bleek, Katharina; Ellinghaus, Agnes; Dienelt, Anke; Peters, Anja; Mehta, Manav; Madl, Christopher M; Huebsch, Nathaniel; Mooney, David J; Duda, Georg N

2017-09-15

In-situ tissue regeneration aims to utilize the body's endogenous healing capacity through the recruitment of host stem or progenitor cells to an injury site. Stromal cell-derived factor-1α (SDF-1α) is widely discussed as a potent chemoattractant. Here we use a cell-free biomaterial-based approach to (i) deliver SDF-1α for the recruitment of endogenous bone marrow-derived stromal cells (BMSC) into a critical-sized segmental femoral defect in rats and to (ii) induce hydrogel stiffness-mediated osteogenic differentiation in-vivo. Ionically crosslinked alginate hydrogels with a stiffness optimized for osteogenic differentiation were used. Fast-degrading porogens were incorporated to impart a macroporous architecture that facilitates host cell invasion. Endogenous cell recruitment to the defect site was successfully triggered through the controlled release of SDF-1α. A trend for increased bone volume fraction (BV/TV) and a significantly higher bone mineral density (BMD) were observed for gels loaded with SDF-1α, compared to empty gels at two weeks. A trend was also observed, albeit not statistically significant, towards matrix stiffness influencing BV/TV and BMD at two weeks. However, over a six week time-frame, these effects were insufficient for bone bridging of a segmental femoral defect. While mechanical cues combined with ex-vivo cell encapsulation have been shown to have an effect in the regeneration of less demanding in-vivo models, such as cranial defects of nude rats, they are not sufficient for a SDF-1α mediated in-situ regeneration approach in segmental femoral defects of immunocompetent rats, suggesting that additional osteogenic cues may also be required. Stromal cell-derived factor-1α (SDF-1α) is a chemoattractant used to recruit host cells for tissue regeneration. The concept that matrix stiffness can direct mesenchymal stromal cell (MSC) differentiation into various lineages was described a decade ago using in-vitro experiments. Recently, alginate hydrogels with an optimized stiffness and ex-vivo encapsulated MSCs were shown to have an effect in the regeneration of skull defects of nude rats. Here, we apply this material system, loaded with SDF-1α and without encapsulated MSCs, to (i) recruit endogenous cells and (ii) induce stiffness-mediated osteogenic differentiation in-vivo, using as model system a load-bearing femoral defect in immunocompetent rats. While a cell-free approach is of great interest from a translational perspective, the current limitations are described. Copyright © 2017 Acta Materialia Inc. Published by Elsevier Ltd. All rights reserved.

Reconstruction of goat femur segmental defects using triphasic ceramic-coated hydroxyapatite in combination with autologous cells and platelet-rich plasma.

PubMed

Nair, Manitha B; Varma, H K; Menon, K V; Shenoy, Sachin J; John, Annie

2009-06-01

Segmental bone defects resulting from trauma or pathology represent a common and significant clinical problem. In this study, a triphasic ceramic (calcium silicate, hydroxyapatite and tricalcium phosphate)-coated hydroxyapatite (HASi) having the benefits of both HA (osteointegration, osteoconduction) and silica (degradation) was used as a bone substitute for the repair of segmental defect (2 cm) created in a goat femur model. Three experimental goat femur implant groups--(a) bare HASi, (b) osteogenic-induced goat bone marrow-derived mesenchymal stem cells cultured HASi (HASi+C) and (c) osteogenic-induced goat bone marrow-derived mesenchymal stem cells cultured HASi+platelet-rich plasma (HASi+CP)--were designed and efficacy performance in the healing of the defect was evaluated. In all the groups, the material united with host bone without any inflammation and an osseous callus formed around the implant. This reflects the osteoconductivity of HASi where the cells have migrated from the cut ends of host bone. The most observable difference between the groups appeared in the mid region of the defect. In bare HASi groups, numerous osteoblast-like cells could be seen together with a portion of material. However, in HASi+C and HASi+CP, about 60-70% of that area was occupied by woven bone, in line with material degradation. The interconnected porous nature (50-500 microm), together with the chemical composition of the HASi, facilitated the degradation of HASi, thereby opening up void spaces for cellular ingrowth and bone regeneration. The combination of HASi with cells and PRP was an added advantage that could promote the expression of many osteoinductive proteins, leading to faster bone regeneration and material degradation. Based on these results, we conclude that bare HASi can aid in bone regeneration but, with the combination of cells and PRP, the sequence of healing events are much faster in large segmental bone defects in weight-bearing areas in goats.

Myocardial contusion in patients with blunt chest trauma as evaluated by thallium 201 myocardial scintigraphy

DOE Office of Scientific and Technical Information (OSTI.GOV)

Bodin, L.; Rouby, J.J.; Viars, P.

1988-07-01

Fifty five patients suffering from blunt chest trauma were studied to assess the diagnosis of myocardial contusion using thallium 201 myocardial scintigraphy. Thirty-eight patients had consistent scintigraphic defects and were considered to have a myocardial contusion. All patients with scintigraphic defects had paroxysmal arrhythmias and/or ECG abnormalities. Of 38 patients, 32 had localized ST-T segment abnormalities; 29, ST-T segment abnormalities suggesting involvement of the same cardiac area as scintigraphic defects; 21, echocardiographic abnormalities. Sixteen patients had segmental hypokinesia involving the same cardiac area as the scintigraphic defects. Fifteen patients had clinical signs suggestive of myocardial contusion and scintigraphic defects. Almostmore » 70 percent of patients with blunt chest trauma had scintigraphic defects related to areas of myocardial contusion. When thallium 201 myocardial scintigraphy directly showed myocardial lesion, two-dimensional echocardiography and standard ECG detected related functional consequences of cardiac trauma.« less

The retinal phenotype of Usher syndrome: pathophysiological insights from animal models.

PubMed

El-Amraoui, Aziz; Petit, Christine

2014-03-01

The Usher syndrome (USH) is the most prevalent cause of inherited deaf-blindness. Three clinical subtypes, USH1-3, have been defined, and ten USH genes identified. The hearing impairment due to USH gene defects has been shown to result from improper organisation of the hair bundle, the sound receptive structure of sensory hair cells. In contrast, the cellular basis of the visual defect is less well understood as this phenotype is absent in almost all the USH mouse models that faithfully mimic the human hearing impairment. Structural and molecular interspecies discrepancies regarding photoreceptor calyceal processes and the association with the distribution of USH1 proteins have recently been unravelled, and have led to the conclusion that a defect in the USH1 protein complex-mediated connection between the photoreceptor outer segment and the surrounding calyceal processes (in both rods and cones), and the inner segment (in rods only), probably causes the USH1 retinal dystrophy in humans. Copyright © 2013 Académie des sciences. Published by Elsevier SAS. All rights reserved.

Physics-Based Image Segmentation Using First Order Statistical Properties and Genetic Algorithm for Inductive Thermography Imaging.

PubMed

Gao, Bin; Li, Xiaoqing; Woo, Wai Lok; Tian, Gui Yun

2018-05-01

Thermographic inspection has been widely applied to non-destructive testing and evaluation with the capabilities of rapid, contactless, and large surface area detection. Image segmentation is considered essential for identifying and sizing defects. To attain a high-level performance, specific physics-based models that describe defects generation and enable the precise extraction of target region are of crucial importance. In this paper, an effective genetic first-order statistical image segmentation algorithm is proposed for quantitative crack detection. The proposed method automatically extracts valuable spatial-temporal patterns from unsupervised feature extraction algorithm and avoids a range of issues associated with human intervention in laborious manual selection of specific thermal video frames for processing. An internal genetic functionality is built into the proposed algorithm to automatically control the segmentation threshold to render enhanced accuracy in sizing the cracks. Eddy current pulsed thermography will be implemented as a platform to demonstrate surface crack detection. Experimental tests and comparisons have been conducted to verify the efficacy of the proposed method. In addition, a global quantitative assessment index F-score has been adopted to objectively evaluate the performance of different segmentation algorithms.

Improved Healing of Large, Osseous, Segmental Defects by Reverse Dynamization: Evaluation in a Sheep Model

DTIC Science & Technology

2016-10-01

characterization of a novel external fixator for dynamizing ovine osseous defects. Poster No. 2185. Orthopedic Research Society Annual Meeting, Orlando...REPORT: Annual PREPARED FOR: U.S. Army Medical Research and Materiel Command Fort Detrick, Maryland 21702-5012 DISTRIBUTION STATEMENT...SPONSOR/MONITOR’S ACRONYM(S) U.S. Army Medical Research and Materiel Command Fort Detrick, Maryland 21702-5012 11. SPONSOR/MONITOR’S REPORT NUMBER(S

High doses of bone morphogenetic protein 2 induce structurally abnormal bone and inflammation in vivo.

PubMed

Zara, Janette N; Siu, Ronald K; Zhang, Xinli; Shen, Jia; Ngo, Richard; Lee, Min; Li, Weiming; Chiang, Michael; Chung, Jonguk; Kwak, Jinny; Wu, Benjamin M; Ting, Kang; Soo, Chia

2011-05-01

The major Food and Drug Association-approved osteoinductive factors in wide clinical use are bone morphogenetic proteins (BMPs). Although BMPs can promote robust bone formation, they also induce adverse clinical effects, including cyst-like bone formation and significant soft tissue swelling. In this study, we evaluated multiple BMP2 doses in a rat femoral segmental defect model and in a minimally traumatic rat femoral onlay model to determine its dose-dependent effects. Results of our femoral segmental defect model established a low BMP2 concentration range (5 and 10 μg/mL, total dose 0.375 and 0.75 μg in 75 μg total volume) unable to induce defect fusion, a mid-range BMP2 concentration range able to fuse the defect without adverse effects (30 μg/mL, total dose 2.25 μg in 75 μg total volume), and a high BMP2 concentration range (150, 300, and 600 μg/mL, total dose 11.25, 22.5, and 45 μg in 75 μg total volume) able to fuse the defect, but with formation of cyst-like bony shells filled with histologically confirmed adipose tissue. In addition, compared to control, 4 mg/mL BMP2 also induced significant tissue inflammatory infiltrates and exudates in the femoral onlay model that was accompanied by increased numbers of osteoclast-like cells at 3, 7, and 14 days. Overall, we consistently reproduced BMP2 side effects of cyst-like bone and soft tissue swelling using high BMP2 concentration approaching the typical human 1500 μg/mL.

High Doses of Bone Morphogenetic Protein 2 Induce Structurally Abnormal Bone and Inflammation In Vivo

PubMed Central

Zara, Janette N.; Siu, Ronald K.; Zhang, Xinli; Shen, Jia; Ngo, Richard; Lee, Min; Li, Weiming; Chiang, Michael; Chung, Jonguk; Kwak, Jinny; Wu, Benjamin M.; Ting, Kang

2011-01-01

The major Food and Drug Association–approved osteoinductive factors in wide clinical use are bone morphogenetic proteins (BMPs). Although BMPs can promote robust bone formation, they also induce adverse clinical effects, including cyst-like bone formation and significant soft tissue swelling. In this study, we evaluated multiple BMP2 doses in a rat femoral segmental defect model and in a minimally traumatic rat femoral onlay model to determine its dose-dependent effects. Results of our femoral segmental defect model established a low BMP2 concentration range (5 and 10 μg/mL, total dose 0.375 and 0.75 μg in 75 μg total volume) unable to induce defect fusion, a mid-range BMP2 concentration range able to fuse the defect without adverse effects (30 μg/mL, total dose 2.25 μg in 75 μg total volume), and a high BMP2 concentration range (150, 300, and 600 μg/mL, total dose 11.25, 22.5, and 45 μg in 75 μg total volume) able to fuse the defect, but with formation of cyst-like bony shells filled with histologically confirmed adipose tissue. In addition, compared to control, 4 mg/mL BMP2 also induced significant tissue inflammatory infiltrates and exudates in the femoral onlay model that was accompanied by increased numbers of osteoclast-like cells at 3, 7, and 14 days. Overall, we consistently reproduced BMP2 side effects of cyst-like bone and soft tissue swelling using high BMP2 concentration approaching the typical human 1500 μg/mL. PMID:21247344

Fabric defect detection based on visual saliency using deep feature and low-rank recovery

NASA Astrophysics Data System (ADS)

Liu, Zhoufeng; Wang, Baorui; Li, Chunlei; Li, Bicao; Dong, Yan

2018-04-01

Fabric defect detection plays an important role in improving the quality of fabric product. In this paper, a novel fabric defect detection method based on visual saliency using deep feature and low-rank recovery was proposed. First, unsupervised training is carried out by the initial network parameters based on MNIST large datasets. The supervised fine-tuning of fabric image library based on Convolutional Neural Networks (CNNs) is implemented, and then more accurate deep neural network model is generated. Second, the fabric images are uniformly divided into the image block with the same size, then we extract their multi-layer deep features using the trained deep network. Thereafter, all the extracted features are concentrated into a feature matrix. Third, low-rank matrix recovery is adopted to divide the feature matrix into the low-rank matrix which indicates the background and the sparse matrix which indicates the salient defect. In the end, the iterative optimal threshold segmentation algorithm is utilized to segment the saliency maps generated by the sparse matrix to locate the fabric defect area. Experimental results demonstrate that the feature extracted by CNN is more suitable for characterizing the fabric texture than the traditional LBP, HOG and other hand-crafted features extraction method, and the proposed method can accurately detect the defect regions of various fabric defects, even for the image with complex texture.

Medical image segmentation based on SLIC superpixels model

NASA Astrophysics Data System (ADS)

Chen, Xiang-ting; Zhang, Fan; Zhang, Ruo-ya

2017-01-01

Medical imaging has been widely used in clinical practice. It is an important basis for medical experts to diagnose the disease. However, medical images have many unstable factors such as complex imaging mechanism, the target displacement will cause constructed defect and the partial volume effect will lead to error and equipment wear, which increases the complexity of subsequent image processing greatly. The segmentation algorithm which based on SLIC (Simple Linear Iterative Clustering, SLIC) superpixels is used to eliminate the influence of constructed defect and noise by means of the feature similarity in the preprocessing stage. At the same time, excellent clustering effect can reduce the complexity of the algorithm extremely, which provides an effective basis for the rapid diagnosis of experts.

Automatic Cell Segmentation in Fluorescence Images of Confluent Cell Monolayers Using Multi-object Geometric Deformable Model.

PubMed

Yang, Zhen; Bogovic, John A; Carass, Aaron; Ye, Mao; Searson, Peter C; Prince, Jerry L

2013-03-13

With the rapid development of microscopy for cell imaging, there is a strong and growing demand for image analysis software to quantitatively study cell morphology. Automatic cell segmentation is an important step in image analysis. Despite substantial progress, there is still a need to improve the accuracy, efficiency, and adaptability to different cell morphologies. In this paper, we propose a fully automatic method for segmenting cells in fluorescence images of confluent cell monolayers. This method addresses several challenges through a combination of ideas. 1) It realizes a fully automatic segmentation process by first detecting the cell nuclei as initial seeds and then using a multi-object geometric deformable model (MGDM) for final segmentation. 2) To deal with different defects in the fluorescence images, the cell junctions are enhanced by applying an order-statistic filter and principal curvature based image operator. 3) The final segmentation using MGDM promotes robust and accurate segmentation results, and guarantees no overlaps and gaps between neighboring cells. The automatic segmentation results are compared with manually delineated cells, and the average Dice coefficient over all distinguishable cells is 0.88.

[The method of accelerating osteanagenesis and revascularization of tissue engineered bone in big animal in vivo].

PubMed

Chen, Bin; Pei, Guo-xian; Wang, Ke; Jin, Dan; Wei, Kuan-hai; Ren, Gao-hong

2003-02-01

To study whether tissue engineered bone can repair the large segment bone defect of large animal or not. To observe what character the fascia flap played during the osteanagenesis and revascularization process of tissue engineered bone. 9 Chinese goats were made 2 cm left tibia diaphyseal defect. The repairing effect of the defects was evaluated by ECT, X-ray and histology. 27 goats were divided into three groups: group of CHAP, the defect was filled with coral hydroxyapatite (CHAP); group of tissue engineered bone, the defect was filled with CHAP + bone marrow stroma cells (BMSc); group of fascia flap, the defect was filled with CHAP + BMSc + fascia flap. After finished culturing and inducing the BMSc, CHAP of group of tissue engineered bone and of fascia flap was combined with it. Making fascia flap, different materials as described above were then implanted separately into the defects. Radionuclide bone imaging was used to monitor the revascularization of the implants at 2, 4, 8 weeks after operation. X-ray examination, optical density index of X-ray film, V-G staining of tissue slice of the implants were used at 4, 8, 12 weeks after operation, and the biomechanical character of the specimens were tested at 12 weeks post operation. In the first study, the defect showed no bone regeneration phenomenon. 2 cm tibia defect was an ideal animal model. In the second study, group of CHAP manifested a little trace of bone regeneration, as to group of tissue engineered bone, the defect was almost repaired totally. In group of fascia flap, with the assistance of fascia flap which gave more chance to making implants to get more nutrient, the repair was quite complete. The model of 2 cm caprine tibia diaphyseal defect cannot be repaired by goat itself and can satisfy the tissue engineering's demands. Tissue engineered bone had good ability to repair large segment tibia defect of goat. Fascia flap can accelerate the revascularization process of tissue engineered bone. And by this way, it augment the ability of tissue engineered bone to repair the large bone defect of goat.

Repair of bone segment defects with surface porous fiber-reinforced polymethyl methacrylate (PMMA) composite prosthesis: histomorphometric incorporation model and characterization by SEM.

PubMed

Hautamäki, Mikko P; Aho, Allan J; Alander, Pasi; Rekola, Jami; Gunn, Jarmo; Strandberg, Niko; Vallittu, Pekka K

2008-08-01

Polymer technology has provided solutions for filling of bone defects in situations where there may be technical or biological complications with autografts, allografts, and metal prostheses. We present an experimental study on segmental bone defect reconstruction using a polymethylmethacrylate-(PMMA-) based bulk polymer implant prosthesis. We concentrated on osteoconductivity and surface characteristics. A critical size segment defect of the rabbit tibia in 19 animals aged 18-24 weeks was reconstructed with a surface porous glass fiber-reinforced (SPF) prosthesis made of polymethylmethacrylate (PMMA). The biomechanical properties of SPF implant material were previously adjusted technically to mimic the properties of normal cortical bone. A plain PMMA implant with no porosity or fiber reinforcement was used as a control. Radiology, histomorphometry, and scanning electron microscopy (SEM) were used for analysis of bone growth into the prosthesis during incorporation. The radiographic and histological incorporation model showed good host bone contact, and strong formation of new bone as double cortex. Histomorphometric evaluation showed that the bone contact index (BCI) at the posterior surface interface was higher with the SPF implant than for the control. The total appositional bone growth over the posterior surface (area %) was also stronger for the SPF implant than for controls. Both bone growth into the porous surface and the BCI results were related to the quality, coverage, and regularity of the microstructure of the porous surface. Porous surface structure enhanced appositional bone growth onto the SPF implant. Under load-bearing conditions the implant appears to function like an osteoconductive prosthesis, which enables direct mobilization and rapid return to full weight bearing.

Optimization of Soft Tissue Management, Spacer Design, and Grafting Strategies for Large Segmental Bone Defects using the Chronic Caprine Tibial Defect Model

DTIC Science & Technology

2015-10-01

Several target genes such as Oct4, Sox2, TGFB, and Col1A1 were generally up-regulated in all sections. In distal sections, VWF, PDGFB, and EGFR were...TGFB, and Col1A1 in all sections. No significant main effects were found for target gene fold-change between outer or inner membrane position or distal

Torque test measurement in segmental bone defects using porous calcium phosphate cement implants.

PubMed

Kroese-Deutman, Henriette C; Wolke, Joop G C; Spauwen, Paul H M; Jansen, John A

2010-10-01

This study was performed to assess the bone healing supporting characteristics of porous calcium phosphate (Ca-P) cement when implanted in a rabbit segmental defect model as well as to determine the reliability of torque testing as a method to verify bone healing. The middiaphyseal radius was chosen as the area to create bilaterally increasing defect sizes (5, 10, and 15 mm), which were either filled with porous Ca-P cement or left open as a control. After 12 weeks of implantation, torque test measurements as well as histological and radiographic evaluation were performed. In two of the open 15 mm control defects, bone bridging was visible at the radiographic and histological evaluation. Bone was observed to be present in all porous Ca-P cement implants (5, 10, and 15 mm defects) after 12 weeks. No significant differences in torque measurements were observed between the 5 and 10 mm filled and open control defects using a t-test. In addition, the mechanical strength of all operated specimens was similar compared with nonoperated bone samples. The torsion data for the 15 mm open defect appeared to be lower compared with the filled 15 mm defect, but no significant difference could be proven. Within the limitation of the study design, porous Ca-P cement implants demonstrated osteoconductive properties and confirmed to be a suitable scaffold material in a weight-bearing situation. Further, the used torque testing method was found to be unreliable for testing the mechanical properties of the healed bone defect.

Application of Morphological Segmentation to Leaking Defect Detection in Sewer Pipelines

PubMed Central

Su, Tung-Ching; Yang, Ming-Der

2014-01-01

As one of major underground pipelines, sewerage is an important infrastructure in any modern city. The most common problem occurring in sewerage is leaking, whose position and failure level is typically idengified through closed circuit television (CCTV) inspection in order to facilitate rehabilitation process. This paper proposes a novel method of computer vision, morphological segmentation based on edge detection (MSED), to assist inspectors in detecting pipeline defects in CCTV inspection images. In addition to MSED, other mathematical morphology-based image segmentation methods, including opening top-hat operation (OTHO) and closing bottom-hat operation (CBHO), were also applied to the defect detection in vitrified clay sewer pipelines. The CCTV inspection images of the sewer system in the 9th district, Taichung City, Taiwan were selected as the experimental materials. The segmentation results demonstrate that MSED and OTHO are useful for the detection of cracks and open joints, respectively, which are the typical leakage defects found in sewer pipelines. PMID:24841247

Segmental bone defects: from cellular and molecular pathways to the development of novel biological treatments

PubMed Central

Pneumaticos, Spyros G; Triantafyllopoulos, Georgios K; Basdra, Efthimia K; Papavassiliou, Athanasios G

2010-01-01

Abstract Several conditions in clinical orthopaedic practice can lead to the development of a diaphyseal segmental bone defect, which cannot heal without intervention. Segmental bone defects have been traditionally treated with bone grafting and/or distraction osteogenesis, methods that have many advantages, but also major drawbacks, such as limited availability, risk of disease transmission and prolonged treatment. In order to overcome such limitations, biological treatments have been developed based on specific pathways of bone physiology and healing. Bone tissue engineering is a dynamic field of research, combining osteogenic cells, osteoinductive factors, such as bone morphogenetic proteins, and scaffolds with osteoconductive and osteoinductive attributes, to produce constructs that could be used as bone graft substitutes for the treatment of segmental bone defects. Scaffolds are usually made of ceramic or polymeric biomaterials, or combinations of both in composite materials. The purpose of the present review is to discuss in detail the molecular and cellular basis for the development of bone tissue engineering constructs. PMID:20345845

Repair of tracheomalacia with inflammatory defect and mediastinitis.

PubMed

Sandu, Kishore; Monnier, Yan; Hurni, Michel; Bernath, Marc-Andre; Monnier, Philippe; Wang, Yabo; Ris, Hans-Beat

2011-01-01

We describe a novel repair of an anterior inflammatory tracheal defect with mediastinitis, which occurred after external tracheal suspension of localized intrathoracic tracheomalacia. The malacic tracheal segment of 4-cm length containing the inflammatory tracheal defect was noncircumferentially resected. A temporary endotracheal silicone stent was introduced, and the trachea was closed by a pedicled pectoralis muscle flap reinforced with an embedded rib segment. Retrieval of the stent 5 months postoperatively resulted in a re-epithelialized, persistently stable, noncollapsible tracheal segment that showed the same diameter and configuration as the nonreconstructed part of the trachea. Copyright © 2011 The Society of Thoracic Surgeons. Published by Elsevier Inc. All rights reserved.

Repair of segmental radial defect with autologous bone marrow aspirate and hydroxyapatite in rabbit radius: A clinical and radiographic evaluation

PubMed Central

Yassine, Kalbaza Ahmed; Mokhtar, Benchohra; Houari, Hemida; Karim, Amara; Mohamed, Melizi

2017-01-01

Aim: Finding an ideal bone substitute to treat large bone defects, delayed union and nonunions remain a challenge for orthopedic surgeons and researchers. Several studies have been conducted on bone regeneration; each has its own advantages and disadvantages. The aim of this study was to evaluate the effect of a combination of hydroxyapatite (HA) powder with autologous bone marrow (BM) aspirate on the repair of segmental radial defect in a rabbit model. Materials and Methods: A total of 36 male and adult New Zealand rabbit with a mean weight of 2.25 kg were used in this study. Approximately, 5 mm defect was created in the mid-shaft of the radius to be filled with HA powder in the control group “HA” (n=18) and with a combination of HA powder and autologous BM aspirate in the test group “HA+BM” (n=18). Animals were observed daily for healing by inspection of the surgical site, and six rabbits of each group were sacrificed at 30, 60, and 90 post-operative days to perform a radiographic evaluation of defect site. Results: Obtained results revealed a better and more rapid bone regeneration in the test group: Since the defect was rapidly and completely filled with mature bone tissue after 90 days. Conclusion: Based on these findings, we could infer that adding a BM aspirate to HA is responsible of a better regeneration process leading to a complete filling of the defect. PMID:28831217

Internal Prosthetic Replacement of Skeletal Segments Lost in Combat Injuries.

DTIC Science & Technology

1973-08-31

osteo- articular bone grafts. Clin. Ortho., 87: 156, 1972. 8. Tuli, S. M.: Bridging of bone defects by massive bone grafts in tumorous conditions. Clin...fashion in its proximal one-third to "prevent distractic ,n of the fragments. The fiber metal segment was then placed in the appropriate defect and the...defect slightly oversized and also osteotomizing the fibula to delete any possible distracting forces or angulating forces. The only complication in

Magnetic resonance imaging study of eye congenital birth defects in mouse model

PubMed Central

Tucker, Zachary; Mongan, Maureen; Meng, Qinghang; Xia, Ying

2017-01-01

Purpose Embryonic eyelid closure is a well-documented morphogenetic episode in mammalian eye development. Detection of eyelid closure defect in humans is a major challenge because eyelid closure and reopen occur entirely in utero. As a consequence, congenital eye defects that are associated with failure of embryonic eyelid closure remain unknown. To fill the gap, we developed a mouse model of defective eyelid closure. This preliminary work demonstrates that the magnetic resonance imaging (MRI) approach can be used for the detection of extraocular muscle abnormalities in the mouse model. Methods Mice with either normal (Map3k1+/−) or defective (Map3k1−/−) embryonic eyelid closure were used in this study. Images of the extraocular muscles were obtained with a 9.4 T high resolution microimaging MRI system. The extraocular muscles were identified, segmented, and measured in each imaging slice using an in-house program. Results In agreement with histological findings, the imaging data show that mice with defective embryonic eyelid closure develop less extraocular muscle than normal mice. In addition, the size of the eyeballs was noticeably reduced in mice with defective embryonic eyelid closure. Conclusions We demonstrated that MRI can potentially be used for the study of extraocular muscle in the mouse model of the eye open-at-birth defect, despite the lack of specificity of muscle group provided by the current imaging resolution. PMID:28848319

Assessment of myocardial viability by dynamic tomographic iodine 123 iodophenylpentadecanoic acid imaging: comparison with rest-redistribution thallium 201 imaging.

PubMed

Iskandrian, A S; Powers, J; Cave, V; Wasserleben, V; Cassell, D; Heo, J

1995-01-01

This study examined the ability of dynamic 123I-labeled iodophenylpentadecanoic acid (IPPA) imaging to detect myocardial viability in patients with left ventricular (LV) dysfunction caused by coronary artery disease. Serial 180-degree single-photon emission computed tomographic (SPECT) images (five sets, 8 minutes each) were obtained starting 4 minutes after injection of 2 to 6 mCi 123I at rest in 21 patients with LV dysfunction (ejection fraction [EF] 34% +/- 11%). The segmental uptake was compared with that of rest-redistribution 201Tl images (20 segments/study). The number of perfusion defects (reversible and fixed) was similar by IPPA and thallium (11 +/- 5 vs 10 +/- 5 segments/patient; difference not significant). There was agreement between IPPA and thallium for presence or absence (kappa = 0.78 +/- 0.03) and nature (reversible, mild fixed, or severe fixed) of perfusion defects (kappa = 0.54 +/- 0.04). However, there were more reversible IPPA defects than reversible thallium defects (7 +/- 4 vs 3 +/- 4 segments/patient; p = 0.001). In 14 patients the EF (by gated pool imaging) improved after coronary revascularization from 33% +/- 11% to 39% +/- 12% (p = 0.002). The number of reversible IPPA defects was greater in the seven patients who had improvement in EF than in the patients without such improvement (10 +/- 4 vs 5 +/- 4 segments/patient; p = 0.075). 123I-labeled IPPA SPECT imaging is a promising new technique for assessment of viability. Reversible defects predict recovery of LV dysfunction after coronary revascularization.

Optimization of Soft Tissue Management, Spacer Design, and Grafting Strategies for Large Segmental Bone Defects using the Chronic Caprine Tibial Defect Model

DTIC Science & Technology

2015-12-01

found with Tukey’s HSD post hoc analysis. Several target genes such as Oct4, Sox2, TGFB, and Col1A1 were generally up-regulated in all sections. In...expression analysis from the Aim 1 samples presented several upregulated target genes such as Oct4, Sox2, TGFB, and Col1A1 in all sections. No...TGFB, and Col1A1 . • Data from cellular analysis, histology, gene expression analysis and microCT are being assembled for the predictive model

Optimization of Soft Tissue Management, Spacer Design, and Grafting Strategies For Large Segmental Bone Defects Using The Chronic Caprine Tibial Defect Model

DTIC Science & Technology

2014-10-01

spacer placed at the time of the “Pre-Procedure”. Autogenous Cancellous Bone Graft (ACBG harvested from the sternum at the time of the treatment...will receive more specialized training and orientation to microCT analysis, both on a theoretical and practical level. He will work with raw CT...adjacent to the PMMA) composed of mononuclear cells and exhibited extensive, diffuse fibrous connective tissue.  Performed histology on goat autogenous

Improved Healing of Large, Osseous, Segmental Defects by Reverse Dynamization: Evaluation in a Sheep Model

DTIC Science & Technology

2014-10-01

initiated. One such fixator has been tested on a cadaveric sheep tibia. In the unlocked, loose position, the axial stiffness of the tibia and fixator...suggested by our previous studies using rats. This aspect of the project is the present focus of attention, and additional cadaver legs will be tested...characterize external fixators). A 3 mm tibial defect was created in the leg of a cadaveric sheep, and stabilized with an experimental external

Tissue specific mutagenic and carcinogenic responses in NER defective mouse models.

PubMed

Wijnhoven, Susan W P; Hoogervorst, Esther M; de Waard, Harm; van der Horst, Gijsbertus T J; van Steeg, Harry

2007-01-03

Several mouse models with defects in genes encoding components of the nucleotide excision repair (NER) pathway have been developed. In NER two different sub-pathways are known, i.e. transcription-coupled repair (TC-NER) and global-genome repair (GG-NER). A defect in one particular NER protein can lead to a (partial) defect in GG-NER, TC-NER or both. GG-NER defects in mice predispose to cancer, both spontaneous as well as UV-induced. As such these models (Xpa, Xpc and Xpe) recapitulate the human xeroderma pigmentosum (XP) syndrome. Defects in TC-NER in humans are associated with Cockayne syndrome (CS), a disease not linked to tumor development. Mice with TC-NER defects (Csa and Csb) are - except for the skin - not susceptible to develop (carcinogen-induced) tumors. Some NER factors, i.e. XPB, XPD, XPF, XPG and ERCC1 have functions outside NER, like transcription initiation and inter-strand crosslink repair. Deficiencies in these processes in mice lead to very severe phenotypes, like trichothiodystrophy (TTD) or a combination of XP and CS. In most cases these animals have a (very) short life span, display segmental progeria, but do not develop tumors. Here we will overview the available NER-related mouse models and will discuss their phenotypes in terms of (chemical-induced) tissue-specific tumor development, mutagenesis and premature aging features.

Optimizing Soft Tissue Management and Spacer Design in Segmental Bone Defects

DTIC Science & Technology

2016-12-01

proximal and distal bone segments. 3. Debride 10 grams of tibialis anterior and gastrocnemius muscles. 4. Place an interlocking intramedullary nail ...using a custom spacer to maintain 5-cm defect length. 5. Place a pre-molded 5 cm long x 2 cm diameter PMMA spacer around the nail in the defect. 6...tibia. 3. Open the IM surrounding the PMMA spacer using a “bomb bay door opening”. 4. Remove the spacer without damaging the membrane or nail . 5

Replacement of segmental bone defects using porous bioceramic cylinders: a biomechanical and X-ray diffraction study.

PubMed

Zhang, C; Wang, J; Feng, H; Lu, B; Song, Z; Zhang, X

2001-03-05

A porous ceramic material [hydroxyapatitetricalcium phosphate (HA-TCP)] was implanted in the femora of 30 dogs to investigate the possibility of using this material to repair segmental bone defects. A bone segment, 1.5 cm in length, was removed from the diaphysis of one femur in each dog to create the defect. Cylinders of corresponding size were inserted into the defects. The animals were divided into three groups with recovery times of 2 months, 4 months, and 6 months, respectively. The implants were harvested and subjected to biomechanic tests (bending strength) and X-ray diffraction analysis. The bending strengths of the implant construct increased gradually over time postoperatively. The values of strength for the three different time groups had significant variations (p < 0.05). The X-ray diffraction analysis indicated that the peaks of the TCP included in the cylinders decreased in intensity after implantation and tended to be similar to those of natural bone by 6 months after operation. Conversely, the peaks for the HA had fewer changes compared with preimplantation values. Based on the results of this experiment it was concluded that the porous HA-TCP ceramic cylinders have potential for repair of segmental bone defects if assisted by adequate stabilizing fixtures during the early postoperative period.

Correlation between spectral-domain OCT findings and visual acuity in X-linked retinoschisis.

PubMed

Yang, Hyun Seung; Lee, Jung Bok; Yoon, Young Hee; Lee, Joo Yong

2014-05-08

To investigate the tomographic characteristics of the outer retina and choroid and their relationship with visual acuity in X-linked juvenile retinoschisis (XLRS) patients using spectral-domain optical coherence tomography (SD-OCT). In this retrospective, observational, case-control study, we analyzed 20 eyes of 10 patients with XLRS using SD-OCT. The clinical and tomographic features of the outer retina, including the external limiting membrane (ELM), inner segment/outer segment (IS/OS) junction, cone cell outer segment tips (COST) line, photoreceptor outer segment (PROS) length, and choroid, were evaluated. As controls, 40 age-, sex-, and refraction-matched healthy eyes (1:2 matched) were randomly selected and imaged in parallel. The most prevalent area of abnormality in the outer retina layer of our patients was the outer plexiform layer (OPL; 60% of all affected eyes) and COST line (75% of all affected eyes). On average, the subfoveal choroid and PROS lengths were 35 μm thicker and 19 μm thinner, respectively, in XLRS patients (P = 0.084 and P < 0.001, respectively). A dominant IS/OS junction, COST line defects, and PROS length were related to patient best-corrected visual acuity (BCVA; P = 0.029, P = 0.001, and P < 0.001, respectively) by univariate analysis. Cone cell outer segment tips line defect and PROS length were the only factors related to BCVA in multivariate analysis (P = 0.028 and 0.003, respectively). Outer plexiform layer and photoreceptor microstructure defects are frequent in XLRS patients. Cone cell outer segment tips line defects and shortened PROS lengths as well as other photoreceptor microstructure defects may be closely related to poor vision in XLRS.

Flow-Through Free Fibula Osteocutaneous Flap in Reconstruction of Tibial Bone, Soft Tissue, and Main Artery Segmental Defects.

PubMed

Li, Zonghuan; Yu, Aixi; Qi, Baiwen; Pan, Zhenyu; Ding, Junhui

2017-08-01

The aim of this report was to present the use of flow-through free fibula osteocutaneous flap for the repair of complex tibial bone, soft tissue, and main artery segmental defects. Five patients with bone, soft tissue, and segmental anterior tibial artery defects were included. The lengths of injured tibial bones ranged from 4 to 7 cm. The sizes of impaired soft tissues were between 9 × 4 and 15 × 6 cm. The lengths of defect of anterior tibial artery segments ranged from 6 to 10 cm. Two patients had distal limb perfusion problems. Flow-through free fibula osteocutaneous flap was performed for all 5 patients. Patients were followed for 12 to 18 months. All wounds healed after 1-stage operation, and all flow-through flaps survived. The distal perfusion after vascular repair was normal in all patients. Superficial necrosis of flap edge was noted in 1 case. After the local debridement and partial thickness skin graft, the flap healed uneventfully, and the surgical operation did not increase injury to the donor site. Satisfactory bone union was achieved in all patients in 2 to 4 months postoperation. Enlargement of fibula graft was observed during follow-up from 12 to 18 months. The functions of adjacent joints were recovered, and all patients were able to walk normally. Flow-through free fibula osteocutaneous flap was shown to be an effective and efficient technique for repairing composite tibial bone, soft tissue, and main artery segmental defects. This 1-stage operation should be useful in clinical practice for the treatment of complex bone, soft tissue, and vessel defects.

Photoreceptor change and visual outcome after idiopathic epiretinal membrane removal with or without additional internal limiting membrane peeling.

PubMed

Ahn, Seong Joon; Ahn, Jeeyun; Woo, Se Joon; Park, Kyu Hyung

2014-01-01

To compare the postoperative photoreceptor status and visual outcome after epiretinal membrane removal with or without additional internal limiting membrane (ILM) peeling. Medical records of 40 eyes from 37 patients undergoing epiretinal membrane removal with residual ILM peeling (additional ILM peeling group) and 69 eyes from 65 patients undergoing epiretinal membrane removal without additional ILM peeling (no additional peeling group) were reviewed. The length of defects in cone outer segment tips, inner segment/outer segment junction, and external limiting membrane line were measured using spectral domain optical coherence tomography images of the fovea before and at 1, 3, 6, and 12 months after the surgery. Cone outer segment tips and inner segment/outer segment junction line defects were most severe at postoperative 1 month and gradually restored at 12 months postoperatively. The cone outer segment tips line defect in the additional ILM peeling group was significantly greater than that in the no additional peeling group at postoperative 1 month (P = 0.006), and best-corrected visual acuity was significantly worse in the former group at the same month (P = 0.001). There was no significant difference in the defect size and best-corrected visual acuity at subsequent visits and recurrence rates between the two groups. Patients who received epiretinal membrane surgery without additional ILM peeling showed better visual and anatomical outcome than those with additional ILM peeling at postoperative 1 month. However, surgical outcomes were comparable between the two groups, thereafter. In terms of visual outcome and photoreceptor integrity, additional ILM peeling may not be an essential procedure.

Bone Marrow Aspirate Concentrate in Animal Long Bone Healing: An Analysis of Basic Science Evidence.

PubMed

Gianakos, Arianna; Ni, Amelia; Zambrana, Lester; Kennedy, John G; Lane, Joseph M

2016-01-01

Long bone fractures that fail to heal or show a delay in healing can lead to increased morbidity. Bone marrow aspirate concentrate (BMAC) containing bone mesenchymal stem cells (BMSCs) has been suggested as an autologous biologic adjunct to aid long bone healing. The purpose of this study was to systematically review the basic science in vivo evidence for the use of BMAC with BMSCs in the treatment of segmental defects in animal long bones. The PubMed/MEDLINE and EMBASE databases were screened in July 14-25, 2014. The following search criteria were used: [("bmac" OR "bone marrow aspirate concentrate" OR "bmc" OR "bone marrow concentrate" OR "mesenchymal stem cells") AND ("bone" OR "osteogenesis" OR "fracture healing" OR "nonunion" OR "delayed union")]. Three authors extracted data and analyzed for trends. Quality of evidence score was given to each study. Results are presented as Hedge G standardized effect sizes with 95% confidence intervals. The search yielded 35 articles for inclusion. Of studies reporting statistics, 100% showed significant increase in bone formation in the BMAC group on radiograph. Ninety percent reported significant improvement in earlier bone healing on histologic/histomorphometric assessment. Eighty-one percent reported a significant increase in bone area on micro-computed tomography. Seventy-eight percent showed a higher torsional stiffness for the BMAC-treated defects. In the in vivo studies evaluated, BMAC confer beneficial effects on the healing of segmental defects in animal long bone models when compared with a control. Proof-of-concept has been established for BMAC in the treatment of animal segmental bone defects.

Uromodulin retention in thick ascending limb of Henle's loop affects SCD1 in neighboring proximal tubule: renal transcriptome studies in mouse models of uromodulin-associated kidney disease.

PubMed

Horsch, Marion; Beckers, Johannes; Fuchs, Helmut; Gailus-Durner, Valérie; Hrabě de Angelis, Martin; Rathkolb, Birgit; Wolf, Eckhard; Aigner, Bernhard; Kemter, Elisabeth

2014-01-01

Uromodulin-associated kidney disease (UAKD) is a hereditary progressive renal disease which can lead to renal failure and requires renal replacement therapy. UAKD belongs to the endoplasmic reticulum storage diseases due to maturation defect of mutant uromodulin and its retention in the enlarged endoplasmic reticulum in the cells of the thick ascending limb of Henle's loop (TALH). Dysfunction of TALH represents the key pathogenic mechanism of UAKD causing the clinical symptoms of this disease. However, the molecular alterations underlying UAKD are not well understood. In this study, transcriptome profiling of whole kidneys of two mouse models of UAKD, UmodA227T and UmodC93F, was performed. Genes differentially abundant in UAKD affected kidneys of both Umod mutant lines at different disease stages were identified and verified by RT-qPCR. Additionally, differential protein abundances of SCD1 and ANGPTL7 were validated by immunohistochemistry and Western blot analysis. ANGPTL7 expression was down-regulated in TALH cells of Umod mutant mice which is the site of the mutant uromodulin maturation defect. SCD1 was expressed selectively in the S3 segment of proximal tubule cells, and SCD1 abundance was increased in UAKD affected kidneys. This finding demonstrates that a cross talk between two functionally distinct tubular segments of the kidney, the TALH segment and the S3 segment of proximal tubule, exists.

7 CFR 51.1837 - Classification of defects.

Code of Federal Regulations, 2014 CFR

2014-01-01

... Definitions § 51.1837 Classification of defects. Table I Factor Damage Serious damage Very serious damage... segments more than 1/8 inch (3.2 mm) at stem end, or the equivalent of this amount, by volume, when occurring in other portions of the fruit Affecting all segments more than 1/4 inch (6.4 mm) at stem end, or...

7 CFR 51.1837 - Classification of defects.

Code of Federal Regulations, 2013 CFR

2013-01-01

... Definitions § 51.1837 Classification of defects. Table I Factor Damage Serious damage Very serious damage... segments more than 1/8 inch (3.2 mm) at stem end, or the equivalent of this amount, by volume, when occurring in other portions of the fruit Affecting all segments more than 1/4 inch (6.4 mm) at stem end, or...

Tool Measures Depths of Defects on a Case Tang Joint

NASA Technical Reports Server (NTRS)

Ream, M. Bryan; Montgomery, Ronald B.; Mecham, Brent A.; Keirstead, Bums W.

2005-01-01

A special-purpose tool has been developed for measuring the depths of defects on an O-ring seal surface. The surface lies in a specially shaped ringlike fitting, called a capture feature tang, located on an end of a cylindrical segment of a case that contains a solid-fuel booster rocket motor for launching a space shuttle. The capture feature tang is a part of a tang-and-clevis, O-ring joint between the case segment and a similar, adjacent cylindrical case segment. When the segments are joined, the tang makes an interference fit with the clevis and squeezes the O-ring at the side of the gap.

[Comparison of initial and delayed myocardial imaging with beta-methyl-p-[123I]-iodophenylpentadecanoic acid in acute myocardial infarction].

PubMed

Naruse, H; Yoshimura, N; Yamamoto, J; Morita, M; Fukutake, N; Ohyanagi, M; Iwasaki, T; Fukuchi, M

1994-01-01

Myocardial imaging using beta-methyl-p-[123I]-iodophenylpentadecanoic acid (BMIPP) of 15 patients with acute myocardial infarction was performed to assess "fill-in" and "washout" defects in the delayed myocardial image. The initial and delayed images were evaluated by a visual and quantitative washout rate method. Visual judgement found 8/180 (4%) segments showed "fill-in" defects, and 24/180 segments (13%) showed "washout" defects. There was no relationship between days from onset to the study and the frequency of fill-in and washout defects. The mean washout rate in the segments with "fill-in" defects was 9.0 +/- 16.6%, and that of "washout" defects was 24.9 +/- 18.1% which was significantly higher than in controls (8.7 +/- 15.4%, p < 0.05). There was no correlation between mean washout rate and total blood lipids, total cholesterol, triglyceride and HDL-cholesterol. Therefore, neither time from onset nor blood lipids level was related to changes from the initial image to the delayed image. These changes may be due to relative (false) findings due to changes in circumference, and may be based on myocardial characteristics after myocardial infarction and/or reperfusion.

Finite element investigation of the effect of a bifid arch on loading of the vertebral isthmus.

PubMed

Quah, Conal; Yeoman, Mark S; Cizinauskas, Andrius; Cooper, Kevin C; Peirce, Nick S; McNally, Donal S; Boszczyk, Bronek M

2014-04-01

The biomechanical effect of a bifid arch as seen in spina bifida occulta and following a midline laminectomy is poorly understood. To test the hypothesis that fatigue failure limits will be exceeded in the case of a bifid arch, but not in the intact case, when the segment is subjected to complex loading corresponding to normal sporting activities. Finite element analysis. Finite element model of an intact L4-S1 human lumbar motion segment including ligaments was used. A section of the L5 vertebral arch and spinous process was removed to create the model with a midline defect. The models were loaded axially to 1 kN and then combined with axial rotation of 3°. Bilateral stresses, alternating stresses, and shear fatigue failure on both models were assessed and compared. Under 1 kN axial load, the von Mises stresses observed in midline defect case and in the intact case were very similar (differences <5 MPa) having a maximum at the ventral end of the isthmus that decreases monotonically to the dorsal end. However, under 1 kN axial load and rotation, the maximum von Mises stresses observed in the ipsilateral L5 isthmus in the midline defect case (31 MPa) was much higher than the intact case (24.2 MPa), indicating a lack of load sharing across the vertebral arch in the midline defect case. When assessing the equivalent alternating shear stress amplitude, this was found to be 22.6 MPa for the midline defect case and 13.6 MPa for the intact case. From this, it is estimated that shear fatigue failure will occur in less than 70,000 cycles, under repetitive axial load and rotation conditions in the midline defect case, whereas for the intact case, fatigue failure will occur only after more than 10 million cycles. A bifid arch predisposes the isthmus to early fatigue fracture by generating increased stresses across the inferior isthmus of the inferior articular process, specifically in combined axial rotation and anteroposterior shear. Copyright © 2014 Elsevier Inc. All rights reserved.

Prognostic validation of a 17-segment score derived from a 20-segment score for myocardial perfusion SPECT interpretation.

PubMed

Berman, Daniel S; Abidov, Aiden; Kang, Xingping; Hayes, Sean W; Friedman, John D; Sciammarella, Maria G; Cohen, Ishac; Gerlach, James; Waechter, Parker B; Germano, Guido; Hachamovitch, Rory

2004-01-01

Recently, a 17-segment model of the left ventricle has been recommended as an optimally weighted approach for interpreting myocardial perfusion single photon emission computed tomography (SPECT). Methods to convert databases from previous 20- to new 17-segment data and criteria for abnormality for the 17-segment scores are needed. Initially, for derivation of the conversion algorithm, 65 patients were studied (algorithm population) (pilot group, n = 28; validation group, n = 37). Three conversion algorithms were derived: algorithm 1, which used mid, distal, and apical scores; algorithm 2, which used distal and apical scores alone; and algorithm 3, which used maximal scores of the distal septal, lateral, and apical segments in the 20-segment model for 3 corresponding segments of the 17-segment model. The prognosis population comprised 16,020 consecutive patients (mean age, 65 +/- 12 years; 41% women) who had exercise or vasodilator stress technetium 99m sestamibi myocardial perfusion SPECT and were followed up for 2.1 +/- 0.8 years. In this population, 17-segment scores were derived from 20-segment scores by use of algorithm 2, which demonstrated the best agreement with expert 17-segment reading in the algorithm population. The prognostic value of the 20- and 17-segment scores was compared by converting the respective summed scores into percent myocardium abnormal. Conversion algorithm 2 was found to be highly concordant with expert visual analysis by the 17-segment model (r = 0.982; kappa = 0.866) in the algorithm population. In the prognosis population, 456 cardiac deaths occurred during follow-up. When the conversion algorithm was applied, extent and severity of perfusion defects were nearly identical by 20- and derived 17-segment scores. The receiver operating characteristic curve areas by 20- and 17-segment perfusion scores were identical for predicting cardiac death (both 0.77 +/- 0.02, P = not significant). The optimal prognostic cutoff value for either 20- or derived 17-segment models was confirmed to be 5% myocardium abnormal, corresponding to a summed stress score greater than 3. Of note, the 17-segment model demonstrated a trend toward fewer mildly abnormal scans and more normal and severely abnormal scans. An algorithm for conversion of 20-segment perfusion scores to 17-segment scores has been developed that is highly concordant with expert visual analysis by the 17-segment model and provides nearly identical prognostic information. This conversion model may provide a mechanism for comparison of studies analyzed by the 17-segment system with previous studies analyzed by the 20-segment approach.

Virtual planning of complex head and neck reconstruction results in satisfactory match between real outcomes and virtual models.

PubMed

Hanken, Henning; Schablowsky, Clemens; Smeets, Ralf; Heiland, Max; Sehner, Susanne; Riecke, Björn; Nourwali, Ibrahim; Vorwig, Oliver; Gröbe, Alexander; Al-Dam, Ahmed

2015-04-01

The reconstruction of large facial bony defects using microvascular transplants requires extensive surgery to achieve full rehabilitation of form and function. The purpose of this study is to measure the agreement between virtual plans and the actual results of maxillofacial reconstruction. This retrospective cohort study included 30 subjects receiving maxillofacial reconstruction with a preoperative virtual planning. Parameters including defect size, position, angle and volume of the transplanted segments were compared between the virtual plan and the real outcome using paired t test. A total of 63 bone segments were transplanted. The mean differences between the virtual planning and the postoperative situation were for the defect sizes 1.17 mm (95 % confidence interval (CI) (-.21 to 2.56 mm); p = 0.094), for the resection planes 1.69 mm (95 % CI (1.26-2.11); p = 0.033) and 10.16° (95 % CI (8.36°-11.96°); p < 0.001) and for the planes of the donor segments 10.81° (95 % CI (9.44°-12.17°); p < 0.001) The orientation of the segments differed by 6.68° (95 % CI (5.7°-7.66°); p < 0.001) from the virtual plan; the length of the segments differed by -0.12 mm (95 % CI (0.89-0.65 mm); not significant (n.s.)), respectively, while the volume differed by 73.3 % (95 % CI (69.4-77.6 %); p < 0.001). The distance between the transplanted segments and the remaining bone was 1.49 mm (95 % CI (1.24-1.74); p < 0.001) and between the segments 1.49 mm (95 % CI (1.16-1.81); p < 0.001). Virtual plans for mandibular and maxillofacial reconstruction can be realised with excellent match. These highly satisfactory postoperative results are the basis for an optimal functional and aesthetic reconstruction in a single surgical procedure. The technique should be further investigated in larger study populations and should be further improved.

Rapid surface defect detection based on singular value decomposition using steel strips as an example

NASA Astrophysics Data System (ADS)

Sun, Qianlai; Wang, Yin; Sun, Zhiyi

2018-05-01

For most surface defect detection methods based on image processing, image segmentation is a prerequisite for determining and locating the defect. In our previous work, a method based on singular value decomposition (SVD) was used to determine and approximately locate surface defects on steel strips without image segmentation. For the SVD-based method, the image to be inspected was projected onto its first left and right singular vectors respectively. If there were defects in the image, there would be sharp changes in the projections. Then the defects may be determined and located according sharp changes in the projections of each image to be inspected. This method was simple and practical but the SVD should be performed for each image to be inspected. Owing to the high time complexity of SVD itself, it did not have a significant advantage in terms of time consumption over image segmentation-based methods. Here, we present an improved SVD-based method. In the improved method, a defect-free image is considered as the reference image which is acquired under the same environment as the image to be inspected. The singular vectors of each image to be inspected are replaced by the singular vectors of the reference image, and SVD is performed only once for the reference image off-line before detecting of the defects, thus greatly reducing the time required. The improved method is more conducive to real-time defect detection. Experimental results confirm its validity.

Chromophores in phenylenevinylene-based conjugated polymers: role of conformational kinks and chemical defects.

PubMed

Hennebicq, Emmanuelle; Deleener, Caroline; Brédas, Jean-Luc; Scholes, Gregory D; Beljonne, David

2006-08-07

The influence of chemical defects and conformational kinks on the nature of the lowest electronic excitations in phenylenevinylene-based polymers is assessed at the semiempirical quantum-chemical level. The amount of excited-state localization and the amplitude of through-space (Coulomb-like) versus through-bond (charge-transfer-like) interactions have been quantified by comparing the results provided by excitonic and supermolecular models. While excitation delocalization among conjugated segments delineated by the defects occurs in the acceptor configuration, self-confinement on individual chromophores follows from geometric relaxation in the excited-state donor configuration. The extent of excited-state localization is found to be sensitive to both the nature of the defect and the length of the conjugated chains. Implications for resonant energy transfer along conjugated polymer chains are discussed.

Autogenous bone particle/titanium fiber composites for bone regeneration in a rabbit radius critical-size defect model.

PubMed

Xie, Huanxin; Ji, Ye; Tian, Qi; Wang, Xintao; Zhang, Nan; Zhang, Yicai; Xu, Jun; Wang, Nanxiang; Yan, Jinglong

2017-11-01

To explore the effects of autogenous bone particle/titanium fiber composites on repairing segmental bone defects in rabbits. A model of bilateral radial bone defect was established in 36 New Zealand white rabbits which were randomly divided into 3 groups according to filling materials used for bilaterally defect treatment: in group C, 9 animal bone defect areas were prepared into simple bilateral radius bone defect (empty sham) as the control group; 27 rabbits were used in groups ABP and ABP-Ti. In group ABP, left defects were simply implanted with autogenous bone particles; meanwhile, group ABP-Ti animals had right defects implanted with autogenous bone particle/titanium fiber composites. Animals were sacrificed at 4, 8, and 12 weeks, respectively, after operation. Micro-CT showed that group C could not complete bone regeneration. Bone volume to tissue volume values in group ABP-Ti were better than group ABP. From histology and histomorphometry Groups ABP and ABP-Ti achieved bone repair, the bone formation of group ABP-Ti was better. The mechanical strength of group ABP-Ti was superior to that of other groups. These results confirmed the effectiveness of autologous bone particle/titanium fiber composites for promoting bone regeneration and mechanical strength.

Color image segmentation to detect defects on fresh ham

NASA Astrophysics Data System (ADS)

Marty-Mahe, Pascale; Loisel, Philippe; Brossard, Didier

2003-04-01

We present in this paper the color segmentation methods that were used to detect appearance defects on 3 dimensional shape of fresh ham. The use of color histograms turned out to be an efficient solution to characterize the healthy skin, but a special care must be taken to choose the color components because of the 3 dimensional shape of ham.

[The monorail system--bone segment transport over unreamed interlocking nails].

PubMed

Oedekoven, G; Jansen, D; Raschke, M; Claudi, B F

1996-11-01

A treatment protocol is demonstrated, consisting of an osteotomy, either proximal or distal, of the bone defect with subsequent segmental transport via an anteromedially (tibia) or laterally (femur) mounted AO external fixation over an unreamed interlocking nail (monorail system). Twenty patients were treated by this method with indications as follows: 13 had a segmental bone defect of the tibia, 3 of the femur. Three patients showed post-traumatic and postinfectious leg-length discrepancies and one was treated for hypertrophic non-union of the femur. Defect distance varied between 5 and 18.5 cm and average time for transport was 19,42 days/ cm for the tibial shaft, 15,93 days/cm for the femur. Two patients developed deep infection, which required change of treatment, removing the monorail system and application of an Ilizarov apparatus. Despite complications using the monorail system, all patients healed and no amputations were required. The monorail system can be used as an alternative to the Ilizarov method under certain criteria of patient selection; these criteria are shown by an algorithm for segmental bone defects without infection, respecting the soft-tissue status with or without neurovascular compromise.

Airborne digital-image data for monitoring the Colorado River corridor below Glen Canyon Dam, Arizona, 2009 - Image-mosaic production and comparison with 2002 and 2005 image mosaics

USGS Publications Warehouse

Davis, Philip A.

2012-01-01

Airborne digital-image data were collected for the Arizona part of the Colorado River ecosystem below Glen Canyon Dam in 2009. These four-band image data are similar in wavelength band (blue, green, red, and near infrared) and spatial resolution (20 centimeters) to image collections of the river corridor in 2002 and 2005. These periodic image collections are used by the Grand Canyon Monitoring and Research Center (GCMRC) of the U.S. Geological Survey to monitor the effects of Glen Canyon Dam operations on the downstream ecosystem. The 2009 collection used the latest model of the Leica ADS40 airborne digital sensor (the SH52), which uses a single optic for all four bands and collects and stores band radiance in 12-bits, unlike the image sensors that GCMRC used in 2002 and 2005. This study examined the performance of the SH52 sensor, on the basis of the collected image data, and determined that the SH52 sensor provided superior data relative to the previously employed sensors (that is, an early ADS40 model and Zeiss Imaging's Digital Mapping Camera) in terms of band-image registration, dynamic range, saturation, linearity to ground reflectance, and noise level. The 2009 image data were provided as orthorectified segments of each flightline to constrain the size of the image files; each river segment was covered by 5 to 6 overlapping, linear flightlines. Most flightline images for each river segment had some surface-smear defects and some river segments had cloud shadows, but these two conditions did not generally coincide in the majority of the overlapping flightlines for a particular river segment. Therefore, the final image mosaic for the 450-kilometer (km)-long river corridor required careful selection and editing of numerous flightline segments (a total of 513 segments, each 3.2 km long) to minimize surface defects and cloud shadows. The final image mosaic has a total of only 3 km of surface defects. The final image mosaic for the western end of the corridor has areas of cloud shadow because of persistent inclement weather during data collection. This report presents visual comparisons of the 2002, 2005, and 2009 digital-image mosaics for various physical, biological, and cultural resources within the Colorado River ecosystem. All of the comparisons show the superior quality of the 2009 image data. In fact, the 2009 four-band image mosaic is perhaps the best image dataset that exists for the entire Arizona part of the Colorado River.

Combination of BMP-2-releasing gelatin/β-TCP sponges with autologous bone marrow for bone regeneration of X-ray-irradiated rabbit ulnar defects.

PubMed

Yamamoto, Masaya; Hokugo, Akishige; Takahashi, Yoshitake; Nakano, Takayoshi; Hiraoka, Masahiro; Tabata, Yasuhiko

2015-07-01

The objective of this study is to evaluate the feasibility of gelatin sponges incorporating β-tricalcium phosphate (β-TCP) granules (gelatin/β-TCP sponges) to enhance bone regeneration at a segmental ulnar defect of rabbits with X-ray irradiation. After X-ray irradiation of the ulnar bone, segmental critical-sized defects of 20-mm length were created, and bone morphogenetic protein-2 (BMP-2)-releasing gelatin/β-TCP sponges with or without autologous bone marrow were applied to the defects to evaluate bone regeneration. Both gelatin/β-TCP sponges containing autologous bone marrow and BMP-2-releasing sponges enhanced bone regeneration at the ulna defect to a significantly greater extent than the empty sponges (control). However, in the X-ray-irradiated bone, the bone regeneration either by autologous bone marrow or BMP-2 was inhibited. When combined with autologous bone marrow, the BMP-2 exhibited significantly high osteoinductivity, irrespective of the X-ray irradiation. The bone mineral content at the ulna defect was similar to that of the intact bone. It is concluded that the combination of bone marrow with the BMP-2-releasing gelatin/β-TCP sponge is a promising technique to induce bone regeneration at segmental bone defects after X-ray irradiation. Copyright © 2015 Elsevier Ltd. All rights reserved.

Improved Healing of Large, Osseous, Segmental Defects by Reverse Dynamization: Evaluation in a Sheep Model

DTIC Science & Technology

2017-12-01

reverse dynamization. This was supplemented by finite element analysis and the use of a strain gauge. This aim was successfully completed, with the...testing deformation results for model validation. Development of a Finite Element (FE) model was conducted through ANSYS 16 to help characterize...Fixators were characterized through mechanical testing by sawbone and ovine cadaver tibiae samples, and data was used to validate a finite element

System and process for detecting and monitoring surface defects

NASA Technical Reports Server (NTRS)

Mueller, Mark K. (Inventor)

1994-01-01

A system and process for detecting and monitoring defects in large surfaces such as the field joints of the container segments of a space shuttle booster motor. Beams of semi-collimated light from three non-parallel fiber optic light panels are directed at a region of the surface at non-normal angles of expected incidence. A video camera gathers some portion of the light that is reflected at an angle other than the angle of expected reflectance, and generates signals which are analyzed to discern defects in the surface. The analysis may be performed by visual inspection of an image on a video monitor, or by inspection of filtered or otherwise processed images. In one alternative embodiment, successive predetermined regions of the surface are aligned with the light source before illumination, thereby permitting efficient detection of defects in a large surface. Such alignment is performed by using a line scan gauge to sense the light which passes through an aperture in the surface. In another embodiment a digital map of the surface is created, thereby permitting the maintenance of records detailing changes in the location or size of defects as the container segment is refurbished and re-used. The defect detection apparatus may also be advantageously mounted on a fixture which engages the edge of a container segment.

Automated Analysis of CT Images for the Inspection of Hardwood Logs

Treesearch

Harbin Li; A. Lynn Abbott; Daniel L. Schmoldt

1996-01-01

This paper investigates several classifiers for labeling internal features of hardwood logs using computed tomography (CT) images. A primary motivation is to locate and classify internal defects so that an optimal cutting strategy can be chosen. Previous work has relied on combinations of low-level processing, image segmentation, autoregressive texture modeling, and...

Effects of Pore Size on the Osteoconductivity and Mechanical Properties of Calcium Phosphate Cement in a Rabbit Model.

PubMed

Zhao, Yi-Nan; Fan, Jun-Jun; Li, Zhi-Quan; Liu, Yan-Wu; Wu, Yao-Ping; Liu, Jian

2017-02-01

Calcium phosphate cement (CPC) porous scaffold is widely used as a suitable bone substitute to repair bone defect, but the optimal pore size is unclear yet. The current study aimed to evaluate the effect of different pore sizes on the processing of bone formation in repairing segmental bone defect of rabbits using CPC porous scaffolds. Three kinds of CPC porous scaffolds with 5 mm diameters and 12 mm length were prepared with the same porosity but different pore sizes (Group A: 200-300 µm, Group B: 300-450 µm, Group C: 450-600 µm, respectively). Twelve millimeter segmental bone defects were created in the middle of the radius bone and filled with different kinds of CPC cylindrical scaffolds. After 4, 12, and 24 weeks, alkaline phosphatase (ALP), histological assessment, and mechanical properties evaluation were performed in all three groups. After 4 weeks, ALP activity increased in all groups but was highest in Group A with smallest pore size. The new bone formation within the scaffolds was not obvious in all groups. After 12 weeks, the new bone formation within the scaffolds was obvious in each group and highest in Group A. At 24 weeks, no significant difference in new bone formation was observed among different groups. Besides the osteoconductive effect, Group A with smallest pore size also had the best mechanical properties in vivo at 12 weeks. We demonstrate that pore size has a significant effect on the osteoconductivity and mechanical properties of calcium phosphate cement porous scaffold in vivo. Small pore size favors the bone formation in the early stage and may be more suitable for repairing segmental bone defect in vivo. © 2016 International Center for Artificial Organs and Transplantation and Wiley Periodicals, Inc.

Mechanical evaluation of anastomotic tension and patency in arteries.

PubMed

Zhang, F; Lineaweaver, W C; Buntic, R; Walker, R

1996-02-01

This study quantified arterial anastomotic tension, evaluated subsequent patency rates, and examined the degree of tension reduction with vessel mobilization. The study was divided into two components. In part I, a mechanical analysis was undertaken to evaluate tension, based on the determination of the force required to deflect a cable (vessel) laterally, and its resulting lateral displacement. Six Sprague-Dawley rats with 12 femoral arteries were divided into two subgroups: 1) no mobilization; and 2) axial mobilization by ligation and transection of superficial epigastric and gracilis muscular branches. The tension of femoral arterial anastomoses was calculated in vessels with no segmental defect and with 1.5-, 3-, 4.5-, 6-, and 7.5-mm defects. In part II, patency was evaluated. Fifty-five rats with 110 femoral arteries were divided into two sub-groups as defined in part I: 1) no mobilization; and 2) axial mobilization by ligation and transection of superficial epigastric and gracilis muscular branches. Microvascular anastomoses were performed with no segmental defect and with 1-, 2-, 3-, 4-, 5-, 6-, 7-, 8-, 9-, and 10-mm segmental vessel defects. Patency was evaluated 24 hr postoperatively. Part I of the study revealed that anastomotic tension gradually increased along with an increase in the length of the vessel defect, from 1.9 to 11.34 g in the no-mobilization group and from 1.97 to 8.44 g in the axial-mobilization group. Comparison of tension linear regression coefficient showed a significant difference between the two groups (p < 0.05). In part II of the study, the maximum length of femoral artery defects still able to maintain 100 percent patency of anastomoses was 4 mm (tension approximately 6 g) in the no-mobilization group and 6 mm in the axial-mobilization group (tension approximately 6.48 g). Microanastomotic tension was related to the size of the vessel defect, with increasing tension leading to thrombosis. Axial mobilization significantly reduced the tension in vessels with segmental defects and decreased thrombosis rates.

Combination of platelet-rich plasma with degradable bioactive borate glass for segmental bone defect repair.

PubMed

Zhang, Ya-Dong; Wang, Gang; Sun, Yan; Zhang, Chang-Qing

2011-02-01

Porous scaffold biomaterials may offer a clinical alternative to bone grafts; however, scaffolds alone are typically insufficient to heal large bone defects. Numerous studies have demonstrated that osteoinductive growth factor significantly improves bone repair. In this study, a strategy combining degradable bioactive borate glass (BG) scaffolds with platelet-rich plasma (PRP) was tested. The bone defect was filled with BG alone, BG combined with autologous PRP or left empty. Bone formation was analyzed at 4, 8 and 12 weeks using both histology and radiology. The PRP treated group yielded better bone formation than the pure BG scaffold as determined by both histology and microcomputer tomography after 12 weeks. In conclusion, PRP improved bone healing in a diaphyseal rabbit model on BG. The combination of PRP and BG may be an effective approach to repair critical defects.

Mobilization of bone marrow mesenchymal stem cells in vivo augments bone healing in a mouse model of segmental bone defect.

PubMed

Kumar, Sanjay; Ponnazhagan, Selvarangan

2012-04-01

Although the number of mesenchymal stem cells (MSC) in the bone marrow is sufficient to maintain skeletal homeostasis, in osteopenic pathology, aggravated osteoclast activity or insufficient osteoblast numbers ensue, affecting normal bone remodeling. Most of the currently available therapies are anti-resorptive with limited osteogenic potential. Since mobilization of stem/progenitors from the BM is a prerequisite for their participation in tissue repair, amplification of endogenous stem cells may provide an alternative approach in these conditions. The present study determined the potential of MSC mobilization in vivo, using combinations of different growth factors with the CXCR4 antagonist, AMD3100, in a mouse model of segmental bone defect. Results indicated that among several factors tested IGF1 had maximum proliferative ability of MSC in vitro. Results of the in vivo studies indicated that the combination of IGF1 and AMD3100 provided significant augmentation of bone growth as determined by DXA, micro-CT and histomorphometry in mice bearing segmental fractures. Further, characterization of MSC isolated from mice treated with IGF1 and AMD3100 indicated Akt/PI3K, MEK1/2-Erk1/2 and smad2/3 as key signaling pathways mediating this effect. These data indicate the potential of in vivo stem cell mobilization as a novel alternative for bone healing. Copyright © 2012 Elsevier Inc. All rights reserved.

Non-destructive detection of cross-sectional strain and defect structure in an individual Ag five-fold twinned nanowire by 3D electron diffraction mapping.

PubMed

Fu, Xin; Yuan, Jun

2017-07-24

Coherent x-ray diffraction investigations on Ag five-fold twinned nanowires (FTNWs) have drawn controversial conclusions concerning whether the intrinsic 7.35° angular gap could be compensated homogeneously through phase transformation or inhomogeneously by forming disclination strain field. In those studies, the x-ray techniques only provided an ensemble average of the structural information from all the Ag nanowires. Here, using three-dimensional (3D) electron diffraction mapping approach, we non-destructively explore the cross-sectional strain and the related strain-relief defect structures of an individual Ag FTNW with diameter about 30 nm. The quantitative analysis of the fine structure of intensity distribution combining with kinematic electron diffraction simulation confirms that for such a Ag FTNW, the intrinsic 7.35° angular deficiency results in an inhomogeneous strain field within each single crystalline segment consistent with the disclination model of stress-relief. Moreover, the five crystalline segments are found to be strained differently. Modeling analysis in combination with system energy calculation further indicates that the elastic strain energy within some crystalline segments, could be partially relieved by the creation of stacking fault layers near the twin boundaries. Our study demonstrates that 3D electron diffraction mapping is a powerful tool for the cross-sectional strain analysis of complex 1D nanostructures.

Software for roof defects recognition on aerial photographs

NASA Astrophysics Data System (ADS)

Yudin, D.; Naumov, A.; Dolzhenko, A.; Patrakova, E.

2018-05-01

The article presents information on software for roof defects recognition on aerial photographs, made with air drones. An areal image segmentation mechanism is described. It allows detecting roof defects – unsmoothness that causes water stagnation after rain. It is shown that HSV-transformation approach allows quick detection of stagnation areas, their size and perimeters, but is sensitive to shadows and changes of the roofing-types. Deep Fully Convolutional Network software solution eliminates this drawback. The tested data set consists of the roofing photos with defects and binary masks for them. FCN approach gave acceptable results of image segmentation in Dice metric average value. This software can be used in inspection automation of roof conditions in the production sector and housing and utilities infrastructure.

Patterns of pulmonary perfusion scans in normal subjects

DOE Office of Scientific and Technical Information (OSTI.GOV)

Wallace, J.M.; Moser, K.M.; Hartman, M.T.

1981-01-01

A vital factor conditioning the usage of the pulmonary perfusion (Q) scan in the evaluation of patients suspected of pulmonary embolism is the prevalence of abnormal Q scans in subjects free of cardiopulmonary disease. Because this prevalence has not been well defined, we performed Q scans in 80 nonsmoking subjects 18 to 29 yr of age having no known active cardiopulmonary disease. Each subject underwent a history, physical examination, electrocardiogram, spirometry, and PA chest roentgenogram, followed by a 6-view Q scan. Two subjects in whom a Q defect was suspected underwent a /sup 133/Xe equilibrium-washout ventilation (V) scan. All Qmore » scans were interpreted blindly and independently by 2 experienced readers. Seventy-nine of the 80 Q scans were read as normal. No subject demonstrated a lobar or segmental defect. One of the 80 subjects, who had a mild pectus excavatum, had a left upper lobe subsegmental defect, which was not seen on the V scan. Based on the statistical analysis of these data, no more than 3.68% of normal nonsmoking persons in this age group may have a lobar or segmental Q scan defect and no more than 6.77% may have a subsegmental defect (with 95% confidence). Therefore, our study indicated that Q scan defects, particularly lobar or segmental, are rarely present among normal nonsmokers in this age group.« less

Segmental liver ischemia/infarction after elective transjugular intrahepatic portosystemic shunt creation: clinical outcomes in 10 patients.

PubMed

Lopera, Jorge E; Katabathina, Venkata; Bosworth, Brian; Garg, Deepak; Kroma, Ghazwan; Garza-Berlanga, Andres; Suri, Rajeev; Wholey, Michael

2015-06-01

To determine the clinical significance and potential mechanisms of segmental liver ischemia and infarction following elective creation of a transjugular intrahepatic portosystemic shunt (TIPS). A retrospective review of 374 elective TIPS creations between March 2006 and September 2014 was performed, yielding 77 contrast-enhanced scans for review. Patients with imaging evidence of segmental perfusion defects were identified. Model for End-stage Liver Disease scores, liver volume, and percentage of liver ischemia/infarct were calculated. Clinical outcomes after TIPS creation were reviewed. Ten patients showed segmental liver ischemia/infarction on contrast-enhanced imaging after elective TIPS creation. Associated imaging findings included thrombosis of the posterior division (n = 7) and anterior division (n = 3) of the right portal vein (PV). The right hepatic vein was thrombosed in 5 patients, as was the middle hepatic vein in 3 and the left hepatic vein in 1. One patient had acute thrombosis of the shunt and main PV. Three patients developed acute liver failure: 2 died within 30 days and 1 required emergent liver transplantation. One patient died of acute renal failure 20 days after TIPS creation. A large infarct in a transplant recipient resulted in biloma formation. Five patients survived without additional interventions with follow-up times ranging from 3 months to 5 years. Segmental perfusion defects are not an uncommon imaging finding after elective TIPS creation. Segmental ischemia was associated with thrombosis of major branches of the PVs and often of the hepatic veins. Clinical outcomes varied significantly, from transient problems to acute liver failure with high mortality rates. Copyright © 2015 SIR. Published by Elsevier Inc. All rights reserved.

Biomechanical Evaluation of an Injectable and Biodegradable Copolymer P(PF-co-CL) in a Cadaveric Vertebral Body Defect Model

PubMed Central

Fang, Zhong; Giambini, Hugo; Zeng, Heng; Camp, Jon J.; Dadsetan, Mahrokh; Robb, Richard A.; An, Kai-Nan; Yaszemski, Michael J.

2014-01-01

A novel biodegradable copolymer, poly(propylene fumarate-co-caprolactone) [P(PF-co-CL)], has been developed in our laboratory as an injectable scaffold for bone defect repair. In the current study, we evaluated the ability of P(PF-co-CL) to reconstitute the load-bearing capacity of vertebral bodies with lytic lesions. Forty vertebral bodies from four fresh-frozen cadaveric thoracolumbar spines were used for this study. They were randomly divided into four groups: intact vertebral body (intact control), simulated defect without treatment (negative control), defect treated with P(PF-co-CL) (copolymer group), and defect treated with poly(methyl methacrylate) (PMMA group). Simulated metastatic lytic defects were made by removing a central core of the trabecular bone in each vertebral body with an approximate volume of 25% through an access hole in the side of the vertebrae. Defects were then filled by injecting either P(PF-co-CL) or PMMA in situ crosslinkable formulations. After the spines were imaged with quantitative computerized tomography, single vertebral body segments were harvested for mechanical testing. Specimens were compressed until failure or to 25% reduction in body height and ultimate strength and elastic modulus of each specimen were then calculated from the force–displacement data. The average failure strength of the copolymer group was 1.83 times stronger than the untreated negative group and it closely matched the intact vertebral bodies (intact control). The PMMA-treated vertebrae, however, had a failure strength 1.64 times larger compared with the intact control. The elastic modulus followed the same trend. This modulus mismatch between PMMA-treated vertebrae and the host vertebrae could potentially induce a fracture cascade and degenerative changes in adjacent intervertebral discs. In contrast, P(PF-co-CL) restored the mechanical properties of the treated segments similar to the normal, intact, vertebrae. Therefore, P(PF-co-CL) may be a suitable alternative to PMMA for vertebroplasty treatment of vertebral bodies with lytic defects. PMID:24256208

Internal bone transport using a cannulated screw as a mounting device in the treatment of a post-infective ulnar defect.

PubMed

Tsitskaris, Konstantinos; Havard, Heledd; Bijlsma, Paulien; Hill, Robert A

2016-04-01

Bone transport techniques can be used to address the segmental bone loss occurring after debridement for infection. Secure fixation of the bone transport construct to the bone transport segment can be challenging, particularly if the bone is small and osteopenic. We report a case of a segmental ulnar bone defect in a young child treated with internal bone transport using a cannulated screw as the mounting device. We found this technique particularly useful in the treatment of bone loss secondary to infection, where previous treatment and prolonged immobilisation had led to osteopenia. This technique has not been previously reported.

Association of ST segment depression >5 min after exercise testing with severity of coronary artery disease.

PubMed

Shaikh, Ayaz Hussain; Hanif, Bashir; Siddiqui, Adeel M; Shahab, Hunaina; Qazi, Hammad Ali; Mujtaba, Iqbal

2010-04-01

To determine the association of prolonged ST segment depression after an exercise test with severity of coronary artery disease. A cross sectional study of 100 consecutive patients referred to the cardiology laboratory for stress myocardial perfusion imaging (MPI) conducted between April-August 2008. All selected patients were monitored until their ST segment depression was recovered to baseline. ST segment recovery time was categorized into less and more than 5 minutes. Subsequent gated SPECT-MPI was performed and stratified according to severity of perfusion defect. Association was determined between post exercise ST segment depression recovery time (<5 minutes and >5 minutes) and severity of perfusion defect on MPI. The mean age of the patients was 57.12 +/- 9.0 years. The results showed statistically insignificant association (p > 0.05) between ST segment recovery time of <5 minutes and >5 minutes with low, intermediate or high risk MPI. Our findings suggest that the commonly used cut-off levels used in literature for prolonged, post exercise ST segment depression (>5 minutes into recovery phase) does not correlate with severity of ischaemia based on MPI results.

A Novel Machine Vision System for the Inspection of Micro-Spray Nozzle

PubMed Central

Huang, Kuo-Yi; Ye, Yu-Ting

2015-01-01

In this study, we present an application of neural network and image processing techniques for detecting the defects of an internal micro-spray nozzle. The defect regions were segmented by Canny edge detection, a randomized algorithm for detecting circles and a circle inspection (CI) algorithm. The gray level co-occurrence matrix (GLCM) was further used to evaluate the texture features of the segmented region. These texture features (contrast, entropy, energy), color features (mean and variance of gray level) and geometric features (distance variance, mean diameter and diameter ratio) were used in the classification procedures. A back-propagation neural network classifier was employed to detect the defects of micro-spray nozzles. The methodology presented herein effectively works for detecting micro-spray nozzle defects to an accuracy of 90.71%. PMID:26131678

A Novel Machine Vision System for the Inspection of Micro-Spray Nozzle.

PubMed

Huang, Kuo-Yi; Ye, Yu-Ting

2015-06-29

In this study, we present an application of neural network and image processing techniques for detecting the defects of an internal micro-spray nozzle. The defect regions were segmented by Canny edge detection, a randomized algorithm for detecting circles and a circle inspection (CI) algorithm. The gray level co-occurrence matrix (GLCM) was further used to evaluate the texture features of the segmented region. These texture features (contrast, entropy, energy), color features (mean and variance of gray level) and geometric features (distance variance, mean diameter and diameter ratio) were used in the classification procedures. A back-propagation neural network classifier was employed to detect the defects of micro-spray nozzles. The methodology presented herein effectively works for detecting micro-spray nozzle defects to an accuracy of 90.71%.

Thermal activation of dislocations in large scale obstacle bypass

NASA Astrophysics Data System (ADS)

Sobie, Cameron; Capolungo, Laurent; McDowell, David L.; Martinez, Enrique

2017-08-01

Dislocation dynamics simulations have been used extensively to predict hardening caused by dislocation-obstacle interactions, including irradiation defect hardening in the athermal case. Incorporating the role of thermal energy on these interactions is possible with a framework provided by harmonic transition state theory (HTST) enabling direct access to thermally activated reaction rates using the Arrhenius equation, including rates of dislocation-obstacle bypass processes. Moving beyond unit dislocation-defect reactions to a representative environment containing a large number of defects requires coarse-graining the activation energy barriers of a population of obstacles into an effective energy barrier that accurately represents the large scale collective process. The work presented here investigates the relationship between unit dislocation-defect bypass processes and the distribution of activation energy barriers calculated for ensemble bypass processes. A significant difference between these cases is observed, which is attributed to the inherent cooperative nature of dislocation bypass processes. In addition to the dislocation-defect interaction, the morphology of the dislocation segments pinned to the defects play an important role on the activation energies for bypass. A phenomenological model for activation energy stress dependence is shown to describe well the effect of a distribution of activation energies, and a probabilistic activation energy model incorporating the stress distribution in a material is presented.

The Design and Use of Animal Models for Translational Research in Bone Tissue Engineering and Regenerative Medicine

DTIC Science & Technology

2010-01-07

many domains: mechanical load bearing and force transmission, immunogologic function (leukogenesis and lymphogenesis), mass transport (erythrogenesis...models including NHPs) does not reproduce upright posture of bipedal humans with respect to axial compression and rotational loading in the human lumbar...Schell, M. Mehta, M. A. Schuetz, G. N. Duda, D. W. Hutmacher. 2012. A Tissue Engineering Solution for Segmental Defect Regeneration in Load - Bearing

Light-leaking region segmentation of FOG fiber based on quality evaluation of infrared image

NASA Astrophysics Data System (ADS)

Liu, Haoting; Wang, Wei; Gao, Feng; Shan, Lianjie; Ma, Yuzhou; Ge, Wenqian

2014-07-01

To improve the assembly reliability of Fiber Optic Gyroscope (FOG), a light leakage detection system and method is developed. First, an agile movement control platform is designed to implement the pose control of FOG optical path component in 6 Degrees of Freedom (DOF). Second, an infrared camera is employed to capture the working state images of corresponding fibers in optical path component after the manual assembly of FOG; therefore the entire light transmission process of key sections in light-path can be recorded. Third, an image quality evaluation based region segmentation method is developed for the light leakage images. In contrast to the traditional methods, the image quality metrics, including the region contrast, the edge blur, and the image noise level, are firstly considered to distinguish the image characters of infrared image; then the robust segmentation algorithms, including graph cut and flood fill, are all developed for region segmentation according to the specific image quality. Finally, after the image segmentation of light leakage region, the typical light-leaking type, such as the point defect, the wedge defect, and the surface defect can be identified. By using the image quality based method, the applicability of our proposed system can be improved dramatically. Many experiment results have proved the validity and effectiveness of this method.

Segmental Bone Regeneration Using a Load Bearing Biodegradable Carrier of Bone Morphogenetic Protein-2

PubMed Central

Chu, Tien-Min G.; Warden, Stuart J.; Turner, Charles H.; Stewart, Rena L.

2006-01-01

Segmental defect regeneration has been a clinical challenge. Current tissue engineering approach using porous biodegradable scaffolds to delivery osteogenic cells and growth factors demonstrated success in facilitating bone regeneration in these cases. However, due to the lack of mechanical property, the porous scaffolds were evaluated in non-load bearing area or were stabilized with stress-shielding devices (bone plate or external fixation). In this paper, we tested a scaffold that does not require a bone plate because it has sufficient biomechanical strength. The tube-shaped scaffolds were manufactured from poly(propylene) fumarate/tricalcium phosphate (PPF/TCP) composites. Dicalcium phosphate dehydrate (DCPD) were used as bone morphogenetic protein -2 (BMP-2) carrier. Twenty two scaffolds were implanted in 5 mm segmental defects in rat femurs stabilized with k-wire for 6 and 15 weeks with and without 10 μg of rhBMP-2. Bridging of the segmental defect was evaluated first radiographically and was confirmed by histology and micro- computer tomography (μ-CT) imaging. The scaffolds in the BMP group maintained the bone length throughout the duration of the study and allow for bridging. The scaffolds in the control group failed to induce bridging and collapsed at 15 weeks. Peripheral computed tomography (pQCT) showed that BMP-2 does not increase the bone mineral density in the callus. Finally, the scaffold in BMP group was found to restore the mechanical property of the rat femur after 15 weeks. Our results demonstrated that the load-bearing BMP-2 scaffold can maintain bone length and allow successfully regeneration in segmental defects. PMID:16996588

Testosterone Delivered with a Scaffold Is as Effective as Bone Morphologic Protein-2 in Promoting the Repair of Critical-Size Segmental Defect of Femoral Bone in Mice

PubMed Central

Cheng, Bi-Hua; Chu, Tien-Min G.; Chang, Chawnshang; Kang, Hong-Yo; Huang, Ko-En

2013-01-01

Loss of large bone segments due to fracture resulting from trauma or tumor removal is a common clinical problem. The goal of this study was to evaluate the use of scaffolds containing testosterone, bone morphogenetic protein-2 (BMP-2), or a combination of both for treatment of critical-size segmental bone defects in mice. A 2.5-mm wide osteotomy was created on the left femur of wildtype and androgen receptor knockout (ARKO) mice. Testosterone, BMP-2, or both were delivered locally using a scaffold that bridged the fracture. Results of X-ray imaging showed that in both wildtype and ARKO mice, BMP-2 treatment induced callus formation within 14 days after initiation of the treatment. Testosterone treatment also induced callus formation within 14 days in wildtype but not in ARKO mice. Micro-computed tomography and histological examinations revealed that testosterone treatment caused similar degrees of callus formation as BMP-2 treatment in wildtype mice, but had no such effect in ARKO mice, suggesting that the androgen receptor is required for testosterone to initiate fracture healing. These results demonstrate that testosterone is as effective as BMP-2 in promoting the healing of critical-size segmental defects and that combination therapy with testosterone and BMP-2 is superior to single therapy. Results of this study may provide a foundation to develop a cost effective and efficient therapeutic modality for treatment of bone fractures with segmental defects. PMID:23940550

Left ventricular rotation and torsion in patients with perimembranous ventricular septal defect.

PubMed

Zhuang, Yan; Yong, Yong-hong; Yao, Jing; Ji, Ling; Xu, Di

2014-03-01

Assessment of left ventricular (LV) rotation has become an important approach for quantifying LV function. In this study, we sought to analyze LV rotation and twist using speckle tracking imaging (STI) in adult patients with isolated ventricular septal defects. Using STI, the peak rotation and time to peak rotation of 6 segments in basal and apical short-axis were measured, respectively, in 32 patients with ventricular septal defect and 30 healthy subjects as controls. The global rotation of the 6 segments in basal and apical and LV twist versus time profile were drawn, the peak rotation and twist of LV were calculated. All the time to peak rotation/twist were expressed as a percentage of end-systole (end-systole = 100%). Left ventricular ejection fraction was measured by biplane Simpson method. In patients group, the peak rotation of posterior, inferior, and postsept wall in basal was higher(P ≤ 0.05) and LV twist was also higher (P ≤ 0.05) than healthy controls. There were no significant differences between 2 groups in the peak rotation of the other 9 segments and left ventricular ejection fraction. Different from the control group, the time to peak rotation of the 6 segments in basal were delayed and the global rotation of the base was delayed (P ≤ 0.05) in ventricular septal defect group. Left ventricular volume overload due to ventricular septal defect has significant effect on LV rotation and twist, and LV rotation and twist may be a new index predicting LV systolic function. © 2013, Wiley Periodicals, Inc.

Fibrin-Genipin Adhesive Hydrogel for Annulus Fibrosus Repair: Performance Evaluation with Large Animal Organ Culture, In Situ Biomechanics, and In Vivo Degradation Tests

PubMed Central

Likhitpanichkul, M.; Dreischarf, M.; Illien-Junger, S.; Walter, B. A.; Nukaga, T.; Long, R. G; Sakai, D.; Hecht, A. C.; Iatridis, J. C.

2015-01-01

Annulus fibrosus (AF) defects from annular tears, herniation, and discectomy procedures are associated with painful conditions and accelerated intervertebral disc (IVD) degeneration. Currently, no effective treatments exist to repair AF damage, restore IVD biomechanics and promote tissue regeneration. An injectable fibrin-genipin adhesive hydrogel (Fib-Gen) was evaluated for its performance repairing large AF defects in a bovine caudal IVD model using ex vivo organ culture and biomechanical testing of motion segments, and for its in vivo longevity and biocompatibility in a rat model by subcutaneous implantation. Fib-Gen sealed AF defects, prevented IVD height loss, and remained well-integrated with native AF tissue following approximately 14,000 cycles of compression in 6-day organ culture experiments. Fib-Gen repair also retained high viability of native AF cells near the repair site, reduced nitric oxide released to the media, and showed evidence of AF cell migration into the gel. Biomechanically, Fib-Gen fully restored compressive stiffness to intact levels validating organ culture findings. However, only partial restoration of tensile and torsional stiffness was obtained, suggesting opportunities to enhance this formulation. Subcutaneous implantation results, when compared with the literature, suggested Fib-Gen exhibited similar biocompatibility behaviour to fibrin alone but degraded much more slowly. We conclude that injectable Fib-Gen successfully sealed large AF defects, promoted functional restoration with improved motion segment biomechanics, and served as a biocompatible adhesive biomaterial that had greatly enhanced in vivo longevity compared to fibrin. Fib-Gen offers promise for AF repairs that may prevent painful conditions and accelerated degeneration of the IVD, and warrants further material development and evaluation. PMID:25036053

Fibrin-genipin adhesive hydrogel for annulus fibrosus repair: performance evaluation with large animal organ culture, in situ biomechanics, and in vivo degradation tests.

PubMed

Likhitpanichkul, M; Dreischarf, M; Illien-Junger, S; Walter, B A; Nukaga, T; Long, R G; Sakai, D; Hecht, A C; Iatridis, J C

2014-07-18

Annulus fibrosus (AF) defects from annular tears, herniation, and discectomy procedures are associated with painful conditions and accelerated intervertebral disc (IVD) degeneration. Currently, no effective treatments exist to repair AF damage, restore IVD biomechanics and promote tissue regeneration. An injectable fibrin-genipin adhesive hydrogel (Fib-Gen) was evaluated for its performance repairing large AF defects in a bovine caudal IVD model using ex vivo organ culture and biomechanical testing of motion segments, and for its in vivo longevity and biocompatibility in a rat model by subcutaneous implantation. Fib-Gen sealed AF defects, prevented IVD height loss, and remained well-integrated with native AF tissue following approximately 14,000 cycles of compression in 6-day organ culture experiments. Fib-Gen repair also retained high viability of native AF cells near the repair site, reduced nitric oxide released to the media, and showed evidence of AF cell migration into the gel. Biomechanically, Fib-Gen fully restored compressive stiffness to intact levels validating organ culture findings. However, only partial restoration of tensile and torsional stiffness was obtained, suggesting opportunities to enhance this formulation. Subcutaneous implantation results, when compared with the literature, suggested Fib-Gen exhibited similar biocompatibility behaviour to fibrin alone but degraded much more slowly. We conclude that injectable Fib-Gen successfully sealed large AF defects, promoted functional restoration with improved motion segment biomechanics, and served as a biocompatible adhesive biomaterial that had greatly enhanced in vivo longevity compared to fibrin. Fib-Gen offers promise for AF repairs that may prevent painful conditions and accelerated degeneration of the IVD, and warrants further material development and evaluation.

Combination of Heel-strike like Mechanical Loading with Deproteinized Cancellous Bone Scaffold Implantation to Repair Segmental Bone Defects in Rabbits.

PubMed

Huang, Guofeng; Liu, Guojun; Zhang, Feng; Gao, Jianting; Wang, Jiangze; Chen, Qi; Wu, Benwen; Ding, Zhenqi; Cai, Taoyi

2017-01-01

Under physiological conditions bone defects often occur at mechanical load bearing sites and bone substitutes used for regeneration should be similarly subjected to mechanical loading stress. In this study, we investigated whether a novel heel-strike like mechanical loading method can be used as a complementary therapy to promote bone regeneration following bone substitute grafting. To test this, three groups of rabbits with segmental bone defects in the tibia were implanted with bovine deproteinized cancellous bone scaffold (DCBS), with one group also receiving heel-strike like mechanical loading generated by a rap stress stimulator. From weeks 4-12 post-operation X-ray and micro-CT scanning showed that rabbits receiving combination therapy had significantly more callus at the bone defect. Moreover, bone defects in the combination group were completely replaced with new bone at week 12, while the DCBS implantation alone group healed only partially and rabbits receiving neither DCBS nor mechanical loading developed only small calluses throughout the observation period. Analysis of micro-CT scanning results demonstrated that new bone density in the combination group was significantly higher than the DCBS only group at weeks 4 and 12 ( p <0.05). H&E staining results also indicated a significantly higher percentage of new bone in the bone defect area and a lower percentage of residual scaffold in the combination group compared to the DCBS only group ( p <0.05). Thus, this heel-strike like mechanical loading method appears to accelerate bone regeneration following substitute implantation by restoring a local mechanical loading environment in segmental bone defects.

Mild (not severe) disc degeneration is implicated in the progression of bilateral L5 spondylolysis to spondylolisthesis.

PubMed

Ramakrishna, Vivek A S; Chamoli, Uphar; Viglione, Luke L; Tsafnat, Naomi; Diwan, Ashish D

2018-04-02

Spondylolytic (or lytic) spondylolisthesis is often associated with disc degeneration at the index-level; however, it is not clear if disc degeneration is the cause or the consequence of lytic spondylolisthesis. The main objective of this computed tomography based finite element modelling study was to examine the role of different grades of disc degeneration in the progression of a bilateral L5-lytic defect to spondylolisthesis. High-resolution computed tomography data of the lumbosacral spine from an anonymised healthy male subject (26 years old) were segmented to build a 3D-computational model of an INTACT L1-S1 spine. The INTACT model was manipulated to generate four more models representing a bilateral L5-lytic defect and the following states of the L5-S1 disc: nil degeneration (NOR LYTIC), mild degeneration (M-DEG LYTIC), mild degeneration with 50% disc height collapse (M-DEG-COL LYTIC), and severe degeneration with 50% disc height collapse(S-COL LYTIC). The models were imported into a finite element modelling software for pre-processing, running nonlinear-static solves, and post-processing of the results. Compared with the baseline INTACT model, M-DEG LYTIC model experienced the greatest increase in kinematics (Fx range of motion: 73% ↑, Fx intervertebral translation: 53%↑), shear stresses in the annulus (Fx anteroposterior: 163%↑, Fx posteroanterior: 31%↑), and strain in the iliolumbar ligament (Fx: 90%↑). The S-COL LYTIC model experienced a decrease in mobility (Fx range of motion: 48%↓, Fx intervertebral translation: 69%↓) and an increase in normal stresses in the annulus (Fx Tensile: 170%↑; Fx Compressive: 397%↑). No significant difference in results was noted between M-DEG-COL LYTIC and S-COL LYTIC models. In the presence of a bilateral L5 spondylolytic defect, a mildly degenerate index-level disc experienced greater intervertebral motions and shear stresses compared with a severely degenerate index-level disc in flexion and extension bending motions. Disc height collapse, with or without degenerative changes in the stiffness properties of the disc, is one of the plausible re-stabilisation mechanisms available to the L5-S1 motion segment to mitigate increased intervertebral motions and shear stresses due to a bilateral L5 lytic defect.

Long-term preservation of retinal function in the RCS rat model of retinitis pigmentosa following lentivirus-mediated gene therapy.

PubMed

Tschernutter, M; Schlichtenbrede, F C; Howe, S; Balaggan, K S; Munro, P M; Bainbridge, J W B; Thrasher, A J; Smith, A J; Ali, R R

2005-04-01

The Royal College of Surgeons (RCS) rat is a well-characterized model of autosomal recessive retinitis pigmentosa (RP) due to a defect in the retinal pigment epithelium (RPE). It is homozygous for a null mutation in the gene encoding , a receptor tyrosine kinase found in RPE cells, that is required for phagocytosis of shed photoreceptor outer segments. The absence of Mertk results in accumulation of outer segment debris. This subsequently leads to progressive loss of photoreceptor cells. In order to evaluate the efficacy of lentiviral-mediated gene replacement therapy in the RCS rat, we produced recombinant VSV-G pseudotyped HIV-1-based lentiviruses containing a murine Mertk cDNA driven by a spleen focus forming virus (SFFV) promoter. The vector was subretinally injected into the right eye of 10-day-old RCS rats; the left eye was left untreated as an internal control. Here, we present a detailed assessment of the duration and extent of the morphological rescue and the resulting functional benefits. We examined animals at various time points over a period of 7 months by light and electron microscopy, and electroretinography. We observed correction of the phagocytic defect, slowing of photoreceptor cell loss and preservation of retinal function for up to 7 months. This study demonstrates the potential of gene therapy approaches for the treatment of retinal degenerations caused by defects specific to the RPE and supports the use of lentiviral vectors for the treatment of such disorders.

Frequency domain reflectometry modeling for nondestructive evaluation of nuclear power plant cables

NASA Astrophysics Data System (ADS)

Glass, S. W.; Fifield, L. S.; Jones, A. M.; Hartman, T. S.

2018-04-01

Cable insulation polymers are among the more susceptible materials to age-related degradation within a nuclear power plant. This is recognized by both regulators and utilities, so all plants have developed cable aging management programs to detect damage before critical component failure in compliance with regulatory guidelines. Although a wide range of tools are available to evaluate cables and cable systems, cable aging management programs vary in how condition monitoring and nondestructive examinations are conducted as utilities search for the most reliable and cost-effective ways to assess cable system condition. Frequency domain reflectometry (FDR) is emerging as one valuable tool to locate and assess damaged portions of a cable system with minimal cost and only requires access in most cases to one of the cable terminal ends. Since laboratory studies to evaluate the use of FDR for inspection of aged cables can be expensive and data interpretation may be confounded by multiple factors which influence results, a model-based approach is desired to parametrically investigate the effect of insulation material damage in a controlled manner. This work describes development of a physics-based FDR model which uses finite element simulations of cable segments in conjunction with cascaded circuit element simulations to efficiently study a cable system. One or more segments of the cable system model have altered physical or electrical properties which represent the degree of damage and the location of the damage in the system. This circuit model is then subjected to a simulated FDR examination. The modeling approach is verified using several experimental cases and by comparing it to a commercial simulator suitable for simulation of some cable configurations. The model is used to examine a broad range of parameters including defect length, defect profile, degree of degradation, number and location of defects, FDR bandwidth, and addition of impedance-matched extensions to minimize the end-shadow effect.

Primary versus secondary achalasia: New signs on barium esophagogram

PubMed Central

Gupta, Pankaj; Debi, Uma; Sinha, Saroj Kant; Prasad, Kaushal Kishor

2015-01-01

Aim: To investigate new signs on barium swallow that can differentiate primary from secondary achalasia. Materials and Methods: Records of 30 patients with primary achalasia and 17 patients with secondary achalasia were reviewed. Clinical, endoscopic, and manometric data was recorded. Barium esophagograms were evaluated for peristalsis and morphology of distal esophageal segment (length, symmetry, nodularity, shouldering, filling defects, and “tram-track sign”). Results: Mean age at presentation was 39 years in primary achalasia and 49 years in secondary achalasia. The mean duration of symptoms was 3.5 years in primary achalasia and 3 months in secondary achalasia. False-negative endoscopic results were noted in the first instance in five patients. In the secondary achalasia group, five patients had distal esophageal segment morphology indistinguishable from that of primary achalasia. None of the patients with primary achalasia and 35% patients with secondary achalasia had a length of the distal segment approaching combined height of two vertebral bodies. None of the patients with secondary achalasia and 34% patients with primary achalasia had maximum caliber of esophagus approaching combined height of two vertebral bodies. Tertiary contractions were noted in 90% patients with primary achalasia and 24% patients with secondary achalasia. Tram-track sign was found in 55% patients with primary achalasia. Filling defects in the distal esophageal segment were noted in 94% patients with secondary achalasia. Conclusion: Length of distal esophageal segment, tertiary contractions, tram-track sign, and filling defects in distal esophageal segment are useful esophagographic features distinguishing primary from secondary achalasia. PMID:26288525

A cascade method for TFT-LCD defect detection

NASA Astrophysics Data System (ADS)

Yi, Songsong; Wu, Xiaojun; Yu, Zhiyang; Mo, Zhuoya

2017-07-01

In this paper, we propose a novel cascade detection algorithm which focuses on point and line defects on TFT-LCD. At the first step of the algorithm, we use the gray level difference of su-bimage to segment the abnormal area. The second step is based on phase only transform (POT) which corresponds to the Discrete Fourier Transform (DFT), normalized by the magnitude. It can remove regularities like texture and noise. After that, we improve the method of setting regions of interest (ROI) with the method of edge segmentation and polar transformation. The algorithm has outstanding performance in both computation speed and accuracy. It can solve most of the defect detections including dark point, light point, dark line, etc.

Laboratory demonstration of an optical vortex mask coronagraph using photonic crystal

NASA Astrophysics Data System (ADS)

Murakami, N.; Baba, N.; Ise, A.; Sakamoto, M.; Oka, K.

2010-10-01

Photonic crystal, artificial periodic nanostructure, is an attractive device for constructing focal-plane phase-mask coronagraphs such as segmented phase masks (four-quadrant, eight-octant, and 4N-segmented ones) and an optical vortex mask (OVM), because of its extremely small manufacturing defect. Recently, speckle-noise limited contrast has been demonstrated for two monochromatic lasers by using the eight-octant phase-mask made of the photonic crystal (Murakami et al. 2010, ApJ, 714, 772). We applied the photonic-crystal device to the OVM coronagraph. The OVM is more advantageous over the segmented phase masks because it does not have discontinuities other than a central singular point and provides a full on-sky field of view. For generating an achromatic optical vortex, we manufactured an axially-symmetric half-wave plate (ASHWP). It is expected that a size of the manufacturing defect due to the central singularity is an order of several hundreds nanometers. The ASHWP is placed between two circular polarizers for modulating a Pancharatnam phase. A continuous spiral phase modulation is then implemented achromatically. We carried out preliminary laboratory demonstration of the OVM coronagraph using two monochromatic lasers as a model star (wavelengths of 532 nm and 633 nm). We report a principle of the achromatic optical-vortex generation, and results of the laboratory demonstration of the OVM coronagraph.

Simultaneous assessment of myocardial perfusion and function during mental stress in patients with chronic coronary artery disease.

PubMed

Arrighi, James A; Burg, Matthew; Cohen, Ira S; Soufer, Robert

2003-01-01

Mental stress (MS) is an important provocateur of myocardial ischemia in many patients with chronic coronary artery disease. The majority of laboratory assessments of ischemia in response to MS have included measurements of either myocardial perfusion or function alone. We performed this study to determine the relationship between alterations in perfusion and ventricular function during MS. Methods and results Twenty-eight patients with reversible perfusion defects on exercise or pharmacologic stress myocardial perfusion imaging (MPI) underwent simultaneous technetium 99m sestamibi single photon emission computed tomography (SPECT) MPI and transthoracic echocardiography at rest and during MS according to a mental arithmetic protocol. In all cases the MS study was performed within 4 weeks of the initial exercise or pharmacologic MPI that demonstrated ischemia. SPECT studies were analyzed visually with the use of a 13-segment model and quantitatively by semiautomated circumferential profile analysis. Echocardiograms were graded on a segmental model for regional wall motion on a 4-point scale. Of 28 patients, 18 (64%) had perfusion defects and/or left ventricular dysfunction develop during MS: 9 (32%) had myocardial perfusion defects develop, 6 (21%) had regional or global left ventricular dysfunction develop, and 3 (11%) had both perfusion defects and left ventricular dysfunction develop. The overall concordance between perfusion and function criteria for ischemia during MS was only 46%. Among 9 patients with MS-induced left ventricular dysfunction, 5 had new regional wall motion abnormalities and 4 had a global decrement in function. In patients with MS-induced ischemia by SPECT, the number of reversible perfusion defects was similar during both MS and exercise/pharmacologic stress (2.8 +/- 2.0 vs 3.5 +/- 1.8, P =.41). Hemodynamic changes during MS were similar whether patients were divided on the basis of perfusion defects or left ventricular dysfunction during MS. These data indicate the feasibility of simultaneous assessment of perfusion and function responses during MS. Flow and function responses to MS are frequently not concordant. These data suggest that MS-induced changes in perfusion may represent a different phenomenon than MS-induced changes in left ventricular function (either globally or regionally).

Reconstruction of segmental bone defect of long bones after tumor resection by devitalized tumor-bearing bone.

PubMed

Qu, Huayi; Guo, Wei; Yang, Rongli; Li, Dasen; Tang, Shun; Yang, Yi; Dong, Sen; Zang, Jie

2015-09-24

The reconstruction of an intercalary bone defect after a tumor resection of a long bone remains a challenge to orthopedic surgeons. Though several methods have been adopted to enhance the union of long segmental allografts or retrieved segmental autografts to the host bones, still more progresses are required to achieve a better union rate. Several methods have been adopted to devitalize tumor bone for recycling usage, and the results varied. We describe our experiences of using devitalized tumor-bearing bones for the repairing of segmental defects after tumor resection. Twenty-seven eligible patients treated from February 2004 to May 2012 were included. The segmental tumor bone (mean length, 14 cm) was resected, and then devitalized in 20% sterile saline at 65 °C for 30 min after the tumor tissue was removed. The devitalized bone was implanted back into the defect by using nails or plates. Complete healing of 50 osteotomy ends was achieved at a median time of 11 months (interquartile range (IQR) 9-13 months). Major complications included bone nonunion in four bone junctions (7.4%), devitalized bone fracture in one patient (3.7%), deep infection in three patients (11.1%), and fixation failure in two patients (7.4%). The bone union rates at 1 and 2 years were 74.1 and 92.6%, respectively. The average functional score according to the Musculoskeletal Tumor Society (MSTS) 93 scoring system was 93 % (IQR 80-96.7%). Incubation in 20% sterile saline at 65 °C for 30 min is an effective method of devitalization of tumor-bearing bone. The retrieved bone graft may provide as a less expensive alternative for limb salvage. The structural bone and the preserved osteoinductivity of protein may improve bone union.

Repair of segmental bone defects in the maxilla by transport disc distraction osteogenesis: Clinical experience with a new device

PubMed Central

Boonzaier, James; Vicatos, George; Hendricks, Rushdi

2015-01-01

The bones of the maxillary complex are vital for normal oro-nasal function and facial cosmetics. Maxillary tumor excision results in large defects that commonly include segments of the alveolar and palatine processes, compromising eating, speech and facial appearance. Unlike the conventional approach to maxillary defect repair by vascularized bone grafting, transport disc distraction osteogenesis (TDDO) stimulates new bone by separating the healing callus, and stimulates growth of surrounding soft tissues as well. Bone formed in this way closely mimics the parent bone in form and internal structure, producing a superior anatomical, functional and cosmetic result. Historically, TDDO has been successfully used to close small horizontal cleft defects in the maxilla, not exceeding 25 mm. Fujioka et al. reported in 2012 that “no bone transporter corresponding to the (large) size of the oro-antral fistula is marketed. The authors report the successful treatment of 4 cases involving alveolar defects of between 25 mm and 80 mm in length. PMID:26389041

The washout rate of (123)I-BMIPP and the evolution of left ventricular function in patients with successfully reperfused ST-segment elevation myocardial infarction: comparisons with the echocardiography.

PubMed

Biswas, Shankar K; Sarai, Masayoshi; Yamada, Akira; Toyama, Hiroshi; Motoyama, Sadako; Harigaya, Hiroto; Hara, Tomonori; Naruse, Hiroyuki; Hishida, Hitoshi; Ozaki, Yukio

2010-02-01

The evolution of the oxidative metabolism of (11)C acetate parallels the recovery of left ventricular(LV) contraction following acute myocardial infarction(AMI). This study was designed to unravel, for the first time, the impact of the global washout rate(WR) of (123)I-beta-methyl-p-iodophenylpentadecanoic acid (BMIPP) on the recovery of LV function followingAMI, as evidenced from conventional echocardiography.Twenty consecutive patients (age: 58 +/- 13 years; 16 males and 4 females) with ST-segment elevation myocardial infarction (STEMI) were enrolled and all of them underwent successful percutaneous coronary intervention (PCI). (123)I-BMIPP cardiac scintigraphy was performed at 7 +/- 3 days after admission. The WR was calculated from the polar map and the regional BMIPP defect score was calculated using a 17 segment model. Echocardiography was performed within 24 h of admission and at 3 months to record the ejection fraction (EF), the wall motion score index (WMSI), the ratio of the mitralinflow velocity to the early diastolic velocity (E/E0)and the myocardial performance index (MPI). The mean global WR of the BMIPP was 22.12 +/- 7.22%, and it was significantly correlated with the improvement of the WMSI (r = 0.61, P\\0.004). However,the relative changes of the EF, E/E0 and MPI were not correlated with the WR. The BMIPP defect score (18 +/- 10) was significantly correlated with the WMSI on admission (r = 0.74, P = 0.0002), but the defect score was not correlated with the relative changes of any of the echocardiographic parameters. We proved that the WR of the BMIPP is a promising indicator of improvement of the LV wall motion (WMSI) following ST-segment elevation myocardial infarction and successful reperfusion.

The mechanical consequence of failure of ossified union in attempted posterior spinal fusion. A canine model.

PubMed

Stonecipher, T K; Vanderby, R; Sciammarella, C A; Lei, S S; Fisk, J R

1983-01-01

The mechanical behavior of pseudarthrosis in posterior spinal fusion was investigated. A canine model was developed in which an incompletely ossified posterior fusion mass was consistently produced. The spines were excised, and the motion segments were mechanically tested using a specially developed loading apparatus. Tests were performed to evaluate stiffness of the segments to loading with compression, torsion, and anterioposterior and lateral bending shear stiffness. Changes in other modes of loading were less consistent. The motion characteristics of the pseudarthrosis could not be predicted from the extent of the osseous defect noted on roentgenograms. These findings correlate clinically with the progression of curvature seen with pseudarthrosis in scoliosis surgery and the unpredictable results of pseudarthrosis in posterior fusion performed in treatment of degenerative disc disease.

Frequency Domain Reflectometry NDE for Aging Cables in Nuclear Power Plants

DOE Office of Scientific and Technical Information (OSTI.GOV)

Glass, Samuel W.; Jones, Anthony M.; Fifield, Leonard S.

Cable insulation polymers are among the more susceptible materials to age-related degradation within a nuclear power plant. This is recognized by both regulators and utilities, so all plants have developed cable aging management programs to detect damage before critical component failure in compliance with regulatory guidelines. Although a wide range of tools are available to evaluate cables and cable systems, cable aging management programs vary in how condition monitoring and nondestructive examinations are conducted as utilities search for the most reliable and cost-effective ways to assess cable system condition. Frequency domain reflectometry (FDR) is emerging as one valuable tool tomore » locate and assess damaged portions of a cable system with minimal cost and only requires access in most cases to one of the cable terminal ends. Since laboratory studies to evaluate the use of FDR for inspection of aged cables can be expensive and data interpretation may be confounded by multiple factors which influence results, a model-based approach is desired to parametrically investigate the effect of insulation material damage in a controlled manner. This work describes development of a physics-based FDR model which uses finite element simulations of cable segments in conjunction with cascaded circuit element simulations to efficiently study a cable system. One or more segments of the cable system model have altered physical or electrical properties which represent the degree of damage and the location of the damage in the system. This circuit model is then subjected to a simulated FDR examination. The modeling approach is verified using several experimental cases and by comparing it to a commercial simulator suitable for simulation of some cable configurations. The model is used to examine a broad range of parameters including defect length, defect profile, degree of degradation, number and location of defects, FDR bandwidth, and addition of impedance-matched extensions to minimize the end-shadow effect.« less

An automated skin segmentation of Breasts in Dynamic Contrast-Enhanced Magnetic Resonance Imaging.

PubMed

Lee, Chia-Yen; Chang, Tzu-Fang; Chang, Nai-Yun; Chang, Yeun-Chung

2018-04-18

Dynamic contrast-enhanced magnetic resonance imaging (DCE-MRI) is used to diagnose breast disease. Obtaining anatomical information from DCE-MRI requires the skin be manually removed so that blood vessels and tumors can be clearly observed by physicians and radiologists; this requires considerable manpower and time. We develop an automated skin segmentation algorithm where the surface skin is removed rapidly and correctly. The rough skin area is segmented by the active contour model, and analyzed in segments according to the continuity of the skin thickness for accuracy. Blood vessels and mammary glands are retained, which remedies the defect of removing some blood vessels in active contours. After three-dimensional imaging, the DCE-MRIs without the skin can be used to see internal anatomical information for clinical applications. The research showed the Dice's coefficients of the 3D reconstructed images using the proposed algorithm and the active contour model for removing skins are 93.2% and 61.4%, respectively. The time performance of segmenting skins automatically is about 165 times faster than manually. The texture information of the tumors position with/without the skin is compared by the paired t-test yielded all p < 0.05, which suggested the proposed algorithm may enhance observability of tumors at the significance level of 0.05.

Photophysics of conjugated polymers: interplay between Förster energy migration and defect concentration in shaping a photochemical funnel in PPV.

PubMed

Saini, Sangeeta; Bagchi, Biman

2010-07-21

Recent single molecule experiments have suggested the existence of a photochemical funnel in the photophysics of conjugated polymers, like poly[2-methoxy-5-(2'-ethylhexyl)oxy-1,4-phenylenevinylene] (MEH-PPV). The funnel is believed to be a consequence of the presence of conformational or chemical defects along the polymer chain and efficient non-radiative energy transfer among different chromophore segments. Here we address the effect of the excitation energy dynamics on the photophysics of PPV. The PPV chain is modeled as a polymer with the length distribution of chromophores given either by a Gaussian or by a Poisson distribution. We observe that the Poisson distribution of the segment lengths explains the photophysics of PPV better than the Gaussian distribution. A recently proposed version of an extended 'particle-in-a-box' model is used to calculate the exciton energies and the transition dipole moments of the chromophores, and a master equation to describe the excitation energy transfer among different chromophores. The rate of energy transfer is assumed to be given here, as a first approximation, by the well-known Förster expression. The observed excitation population dynamics confirms the photochemical funneling of excitation energy from shorter to longer chromophores of the polymer chain. The time scale of spectral shift and energy transfer for our model polymer, with realistic values of optical parameters, is in the range of 200-300 ps. We find that the excitation energy may not always migrate towards the longest chromophore segments in the polymer chain as the efficiency of energy transfer between chromophores depends on the separation distance between the two and their relative orientation.

Adaptive Stress Response in Segmental Progeria Resembles Long-Lived Dwarfism and Calorie Restriction in Mice

PubMed Central

Holcomb, Valerie B; von Lindern, Marieke; Jong, Willeke M. C; Zeeuw, Chris I. De; Suh, Yousin; Hasty, Paul; Hoeijmakers, Jan H. J; van der Horst, Gijsbertus T. J; Mitchell, James R

2006-01-01

How congenital defects causing genome instability can result in the pleiotropic symptoms reminiscent of aging but in a segmental and accelerated fashion remains largely unknown. Most segmental progerias are associated with accelerated fibroblast senescence, suggesting that cellular senescence is a likely contributing mechanism. Contrary to expectations, neither accelerated senescence nor acute oxidative stress hypersensitivity was detected in primary fibroblast or erythroblast cultures from multiple progeroid mouse models for defects in the nucleotide excision DNA repair pathway, which share premature aging features including postnatal growth retardation, cerebellar ataxia, and death before weaning. Instead, we report a prominent phenotypic overlap with long-lived dwarfism and calorie restriction during postnatal development (2 wk of age), including reduced size, reduced body temperature, hypoglycemia, and perturbation of the growth hormone/insulin-like growth factor 1 neuroendocrine axis. These symptoms were also present at 2 wk of age in a novel progeroid nucleotide excision repair-deficient mouse model (XPDG602D/R722W/XPA−/−) that survived weaning with high penetrance. However, despite persistent cachectic dwarfism, blood glucose and serum insulin-like growth factor 1 levels returned to normal by 10 wk, with hypoglycemia reappearing near premature death at 5 mo of age. These data strongly suggest changes in energy metabolism as part of an adaptive response during the stressful period of postnatal growth. Interestingly, a similar perturbation of the postnatal growth axis was not detected in another progeroid mouse model, the double-strand DNA break repair deficient Ku80 −/− mouse. Specific (but not all) types of genome instability may thus engage a conserved response to stress that evolved to cope with environmental pressures such as food shortage. PMID:17173483

Adaptive stress response in segmental progeria resembles long-lived dwarfism and calorie restriction in mice.

PubMed

van de Ven, Marieke; Andressoo, Jaan-Olle; Holcomb, Valerie B; von Lindern, Marieke; Jong, Willeke M C; De Zeeuw, Chris I; Suh, Yousin; Hasty, Paul; Hoeijmakers, Jan H J; van der Horst, Gijsbertus T J; Mitchell, James R

2006-12-15

How congenital defects causing genome instability can result in the pleiotropic symptoms reminiscent of aging but in a segmental and accelerated fashion remains largely unknown. Most segmental progerias are associated with accelerated fibroblast senescence, suggesting that cellular senescence is a likely contributing mechanism. Contrary to expectations, neither accelerated senescence nor acute oxidative stress hypersensitivity was detected in primary fibroblast or erythroblast cultures from multiple progeroid mouse models for defects in the nucleotide excision DNA repair pathway, which share premature aging features including postnatal growth retardation, cerebellar ataxia, and death before weaning. Instead, we report a prominent phenotypic overlap with long-lived dwarfism and calorie restriction during postnatal development (2 wk of age), including reduced size, reduced body temperature, hypoglycemia, and perturbation of the growth hormone/insulin-like growth factor 1 neuroendocrine axis. These symptoms were also present at 2 wk of age in a novel progeroid nucleotide excision repair-deficient mouse model (XPD(G602D/R722W)/XPA(-/-)) that survived weaning with high penetrance. However, despite persistent cachectic dwarfism, blood glucose and serum insulin-like growth factor 1 levels returned to normal by 10 wk, with hypoglycemia reappearing near premature death at 5 mo of age. These data strongly suggest changes in energy metabolism as part of an adaptive response during the stressful period of postnatal growth. Interestingly, a similar perturbation of the postnatal growth axis was not detected in another progeroid mouse model, the double-strand DNA break repair deficient Ku80(-/-) mouse. Specific (but not all) types of genome instability may thus engage a conserved response to stress that evolved to cope with environmental pressures such as food shortage.

Preparation of porous PLA/DBM composite biomaterials and experimental research of repair rabbit radius segmental bone defect.

PubMed

Zhang, Yumin; Wang, Jianru; Wang, Jue; Niu, Xiaojun; Liu, Jianchun; Gao, Lan; Zhai, Xiaoyan; Chu, Kaibo

2015-12-01

Bone substitutes are used in wide range of orthopaedic application. An ideal bone substitute should exhibit superior osteoinductive and osteoconductive properties. Neither bio-derived materials nor synthetic materials can meet the needs of an ideal bone substitute. Preparation of composite materials is a promising way to improve properties of biomaterial. In this study, the porous poly lactic acid (PLA)/demineralized bone matrix (DBM) composite biomaterials prepared by supercritical CO2 technique were implanted to repair rabbit radius segmental bone defect. By comparing with PLA and bone autograft, the X-ray result and histological analysis showed the repair effect of PLA/DBM porous composite materials is significantly better than that of the PLA group and the blank control group, and is similar to autologous bone. The PLA/DBM can promote the healing of bone defects and can be used as a kind of ideal alternative materials to repair bone defects.

Improved Healing of Large, Osseous, Segmental Defects by Reverse Dynamization: Evaluation in a Sheep Model

DTIC Science & Technology

2015-10-01

practical examination of current methods,” J. Biomech., Oct. 2015. [8] R. J. Nesbitt, S . T. Herfat, D. V. Boguszewski, A . J. Engel, M . T. Galloway, and J... a Sheep Model 5b. GRANT NUMBER W81XWH-13-1-0324 5c. PROGRAM ELEMENT NUMBER 6. AUTHOR( S ) Christopher H. Evans, Ph.D. 5d. PROJECT NUMBER...interfragmentary movement ( IFM ) through the separated bone cortices (fracture gap). In research funded by a CDMRP Idea Development Award, we used a

Tracheal reconstruction with autogenous jejunal microsurgical transfer.

PubMed

Jones, R E; Morgan, R F; Marcella, K L; Mills, S E; Kron, I L

1986-06-01

Tracheal defects due to stricture formation, tracheomalacia, and neoplasms can present difficult reconstructive problems. Tracheal defects were surgically created in 6 dogs and primarily reconstructed with microsurgical free tissue transfer of autogenous jejunal segments. Primary healing was accomplished in all dogs without severe air leakage or infection. Bronchoscopy demonstrated no substantial secretions or tracheal narrowing. Gross pathological examination of the trachea revealed no evidence of tracheal disruption or infection. Direct measurements revealed no major tracheal narrowing. Microscopic examination demonstrated normal jejunal mucosa with a minimal amount of inflammatory change at the margins of the reconstruction at 6 weeks. Microvascular free tissue transfer of jejunal segments to correct cervical tracheal defects can readily be accomplished with excellent healing and maintenance of the tracheal lumen in dogs.

Abnormal photoreceptor outer segment development and early retinal degeneration in kif3a mutant zebrafish.

PubMed

Raghupathy, Rakesh K; Zhang, Xun; Alhasani, Reem H; Zhou, Xinzhi; Mullin, Margaret; Reilly, James; Li, Wenchang; Liu, Mugen; Shu, Xinhua

2016-08-01

Photoreceptors are highly specialized sensory neurons that possess a modified primary cilium called the outer segment. Photoreceptor outer segment formation and maintenance require highly active protein transport via a process known as intraflagellar transport. Anterograde transport in outer segments is powered by the heterotrimeric kinesin II and coordinated by intraflagellar transport proteins. Here, we describe a new zebrafish model carrying a nonsense mutation in the kinesin II family member 3A (kif3a) gene. Kif3a mutant zebrafish exhibited curved body axes and kidney cysts. Outer segments were not formed in most parts of the mutant retina, and rhodopsin was mislocalized, suggesting KIF3A has a role in rhodopsin trafficking. Both rod and cone photoreceptors degenerated rapidly between 4 and 9 days post fertilization, and electroretinography response was not detected in 7 days post fertilization mutant larvae. Loss of KIF3A in zebrafish also resulted in an intracellular transport defect affecting anterograde but not retrograde transport of organelles. Our results indicate KIF3A plays a conserved role in photoreceptor outer segment formation and intracellular transport. Copyright © 2016 John Wiley & Sons, Ltd.

Chitin biological absorbable catheters bridging sural nerve grafts transplanted into sciatic nerve defects promote nerve regeneration.

PubMed

Wang, Zhi-Yong; Wang, Jian-Wei; Qin, Li-Hua; Zhang, Wei-Guang; Zhang, Pei-Xun; Jiang, Bao-Guo

2018-06-01

To investigate the efficacy of chitin biological absorbable catheters in a rat model of autologous nerve transplantation. A segment of sciatic nerve was removed to produce a sciatic nerve defect, and the sural nerve was cut from the ipsilateral leg and used as a graft to bridge the defect, with or without use of a chitin biological absorbable catheter surrounding the graft. The number and morphology of regenerating myelinated fibers, nerve conduction velocity, nerve function index, triceps surae muscle morphology, and sensory function were evaluated at 9 and 12 months after surgery. All of the above parameters were improved in rats in which the nerve graft was bridged with chitin biological absorbable catheters compared with rats without catheters. The results of this study indicate that use of chitin biological absorbable catheters to surround sural nerve grafts bridging sciatic nerve defects promotes recovery of structural, motor, and sensory function and improves muscle fiber morphology. © 2018 John Wiley & Sons Ltd.

Correction of the retinal dystrophy phenotype of the RCS rat by viral gene transfer of Mertk.

PubMed

Vollrath, D; Feng, W; Duncan, J L; Yasumura, D; D'Cruz, P M; Chappelow, A; Matthes, M T; Kay, M A; LaVail, M M

2001-10-23

The Royal College of Surgeons (RCS) rat is a widely studied animal model of retinal degeneration in which the inability of the retinal pigment epithelium (RPE) to phagocytize shed photoreceptor outer segments leads to a progressive loss of rod and cone photoreceptors. We recently used positional cloning to demonstrate that the gene Mertk likely corresponds to the retinal dystrophy (rdy) locus of the RCS rat. In the present study, we sought to determine whether gene transfer of Mertk to a RCS rat retina would result in correction of the RPE phagocytosis defect and preservation of photoreceptors. We used subretinal injection of a recombinant replication-deficient adenovirus encoding rat Mertk to deliver the gene to the eyes of young RCS rats. Electrophysiological assessment of animals 30 days after injection revealed an increased sensitivity of treated eyes to low-intensity light. Histologic and ultrastructural assessment demonstrated substantial sparing of photoreceptors, preservation of outer segment structure, and correction of the RPE phagocytosis defect in areas surrounding the injection site. Our results provide definitive evidence that mutation of Mertk underlies the RCS retinal dystrophy phenotype, and that the phenotype can be corrected by treatment of juvenile animals. To our knowledge, this is the first demonstration of complementation of both a functional cellular defect (phagocytosis) and a photoreceptor degeneration by gene transfer to the RPE. These results, together with the recent discovery of MERTK mutations in individuals with retinitis pigmentosa, emphasize the importance of the RCS rat as a model for gene therapy of diseases that arise from RPE dysfunction.

"Palmar pivot flap" for resurfacing palmar lateral defects of the fingers.

PubMed

Yam, Andrew; Peng, Yeong-Pin; Pho, Robert Wan-Heng

2008-12-01

Soft tissue defects on the lateral borders of the digits are difficult to reconstruct using local or local-regional flaps. We describe a "palmar pivot flap" to resurface an adjacent defect on the palmar-lateral aspect of the digit. The surgical technique is described. This flap is an axial pattern flap based on the subcutaneous transverse branches of the digital artery. The flap is pivoted up to 90 degrees on the neurovascular bundle in its base, into an adjacent defect. The flap can be raised from either the proximal or the middle phalangeal segments. It can cover defects sited from the level of the proximal interphalangeal joint up to the fingertip. The donor defect is limited to the same digit and is covered with a full-thickness skin graft. We have used this flap on 3 patients with defects at the middle phalangeal segment, the distal interphalangeal joint, and the fingertip. All healed primarily. One patient had a mild flexion contracture of the proximal interphalangeal joint, whereas the other 2 had no complications. The patients with distal interphalangeal joint and fingertip defects had excellent sensation in the flap (2-point discrimination of 5-6 mm). The palmar pivot flap is useful for resurfacing otherwise difficult defects on the lateral borders of the digits around and distal to the proximal interphalangeal joint, including those at the fingertip. It provides sensate, glabrous skin. The donor defect is on the same digit and is well hidden, producing an aesthetic and functional reconstruction.

[Visual rehabilitation of patients with large post-traumatic defects of the anterior eye segment through iris-lens diaphragm implantation].

PubMed

Khodzhaev, N S; Sobolev, N P; Mushkova, I A; Izmaylova, S B; Karimova, A N

The diversity of methodological approaches and lack of pathogenetically reasonable tactics for patients with combined ocular injuries became the basis for the development and systematization of surgical rehabilitation stages of patients, in whom post-traumatic cataract is combined with post-traumatic aniridia and corneal scarring. to construct a visual rehabilitation approach to patients with post-traumatic defects of the anterior eye segment following optical-reconstructive surgery that involved implantation of an iris-lens diaphragm (ILD). We have analyzed 80 reconstructive cases with ILD implantation in patients with post-traumatic aniridia and corneal damage. These patients constituted the first study group (Group 1). We have also investigated 58 eyes with residual ametropy and stable visual function 1 year after ILD implantation before and after conducting a laser keratorefractive surgery. These patients were assigned to the second study group (Group 2). Rehabilitation approach to patients after anterior segment injuries that has been proposed allows to achieve high clinical and functional results and reduce the risk of intra- and postoperative complications. The proposed approach to patients after optical-reconstructive surgery with iris-lens diaphragm implantation followed by keratorefractive surgery is an effective method of visual rehabilitation of anterior eye segment post-traumatic defects.

Differences in neural crest sensitivity to ethanol account for the infrequency of anterior segment defects in the eye compared with craniofacial anomalies in a zebrafish model of fetal alcohol syndrome.

PubMed

Eason, Jessica; Williams, Antionette L; Chawla, Bahaar; Apsey, Christian; Bohnsack, Brenda L

2017-09-01

Ethanol (ETOH) exposure during pregnancy is associated with craniofacial and neurologic abnormalities, but infrequently disrupts the anterior segment of the eye. In these studies, we used zebrafish to investigate differences in the teratogenic effect of ETOH on craniofacial, periocular, and ocular neural crest. Zebrafish eye and neural crest development was analyzed by means of live imaging, TUNEL (terminal deoxynucleotidyl transferase dUTP nick end labeling) assay, immunostaining, detection of reactive oxygen species, and in situ hybridization. Our studies demonstrated that foxd3-positive neural crest cells in the periocular mesenchyme and developing eye were less sensitive to ETOH than sox10-positive craniofacial neural crest cells that form the pharyngeal arches and jaw. ETOH increased apoptosis in the retina, but did not affect survival of periocular and ocular neural crest cells. ETOH also did not increase reactive oxygen species within the eye. In contrast, ETOH increased ventral neural crest apoptosis and reactive oxygen species production in the facial mesenchyme. In the eye and craniofacial region, sod2 showed high levels of expression in the anterior segment and in the setting of Sod2 knockdown, low levels of ETOH decreased migration of foxd3-positive neural crest cells into the developing eye. However, ETOH had minimal effect on the periocular and ocular expression of transcription factors (pitx2 and foxc1) that regulate anterior segment development. Neural crest cells contributing to the anterior segment of the eye exhibit increased ability to withstand ETOH-induced oxidative stress and apoptosis. These studies explain the rarity of anterior segment dysgenesis despite the frequent craniofacial abnormalities in fetal alcohol syndrome. Birth Defects Research 109:1212-1227, 2017. © 2017 Wiley Periodicals, Inc. © 2017 Wiley Periodicals, Inc.

Analysis of Ablative Performance of C/C Composite Throat Containing Defects Based on X-ray 3D Reconstruction in a Solid Rocket Motor

NASA Astrophysics Data System (ADS)

Hui, Wei-Hua; Bao, Fu-Ting; Wei, Xiang-Geng; Liu, Yang

2015-12-01

In this paper, a new measuring method of ablation rate was proposed based on X-ray three-dimensional (3D) reconstruction. The ablation of 4-direction carbon/carbon composite nozzles was investigated in the combustion environment of a solid rocket motor, and the macroscopic ablation and linear recession rate were studied through the X-ray 3D reconstruction method. The results showed that the maximum relative error of the X-ray 3D reconstruction was 0.0576%, which met the minimum accuracy of the ablation analysis; along the nozzle axial direction, from convergence segment, throat to expansion segment, the ablation gradually weakened; in terms of defect ablation, the middle ablation was weak, while the ablation in both sides was more serious. In a word, the proposed reconstruction method based on X-ray about C/C nozzle ablation can construct a clear model of ablative nozzle which characterizes the details about micro-cracks, deposition, pores and surface to analyze ablation, so that this method can create the ablation curve in any surface clearly.

Usher syndrome type 1–associated cadherins shape the photoreceptor outer segment

PubMed Central

Parain, Karine; Aghaie, Asadollah; Picaud, Serge

2017-01-01

Usher syndrome type 1 (USH1) causes combined hearing and sight defects, but how mutations in USH1 genes lead to retinal dystrophy in patients remains elusive. The USH1 protein complex is associated with calyceal processes, which are microvilli of unknown function surrounding the base of the photoreceptor outer segment. We show that in Xenopus tropicalis, these processes are connected to the outer-segment membrane by links composed of protocadherin-15 (USH1F protein). Protocadherin-15 deficiency, obtained by a knockdown approach, leads to impaired photoreceptor function and abnormally shaped photoreceptor outer segments. Rod basal outer disks displayed excessive outgrowth, and cone outer segments were curved, with lamellae of heterogeneous sizes, defects also observed upon knockdown of Cdh23, encoding cadherin-23 (USH1D protein). The calyceal processes were virtually absent in cones and displayed markedly reduced F-actin content in rods, suggesting that protocadherin-15–containing links are essential for their development and/or maintenance. We propose that calyceal processes, together with their associated links, control the sizing of rod disks and cone lamellae throughout their daily renewal. PMID:28495838

Usher syndrome type 1-associated cadherins shape the photoreceptor outer segment.

PubMed

Schietroma, Cataldo; Parain, Karine; Estivalet, Amrit; Aghaie, Asadollah; Boutet de Monvel, Jacques; Picaud, Serge; Sahel, José-Alain; Perron, Muriel; El-Amraoui, Aziz; Petit, Christine

2017-06-05

Usher syndrome type 1 (USH1) causes combined hearing and sight defects, but how mutations in USH1 genes lead to retinal dystrophy in patients remains elusive. The USH1 protein complex is associated with calyceal processes, which are microvilli of unknown function surrounding the base of the photoreceptor outer segment. We show that in Xenopus tropicalis , these processes are connected to the outer-segment membrane by links composed of protocadherin-15 (USH1F protein). Protocadherin-15 deficiency, obtained by a knockdown approach, leads to impaired photoreceptor function and abnormally shaped photoreceptor outer segments. Rod basal outer disks displayed excessive outgrowth, and cone outer segments were curved, with lamellae of heterogeneous sizes, defects also observed upon knockdown of Cdh23 , encoding cadherin-23 (USH1D protein). The calyceal processes were virtually absent in cones and displayed markedly reduced F-actin content in rods, suggesting that protocadherin-15-containing links are essential for their development and/or maintenance. We propose that calyceal processes, together with their associated links, control the sizing of rod disks and cone lamellae throughout their daily renewal. © 2017 Schietroma et al.

Segmental liver incarceration through a recurrent incisional lumbar hernia.

PubMed

Salemis, Nikolaos S; Nisotakis, Konstantinos; Gourgiotis, Stavros; Tsohataridis, Efstathios

2007-08-01

Lumbar hernia is a rare congenital or acquired defect of the posterior abdominal wall. The acquired type is more common and occurs mainly as an incisional defect after flank surgery. Incarceration or strangulation of hernia contents is uncommon. Segmental liver incarceration through a recurrent incisional lumbar defect was diagnosed in a 58 years old woman by magnetic resonance imaging. The patient underwent an open repair of the complicated hernia. An expanded polytetraflouoroethylene (e-PTFE) mesh was fashioned as a sublay prosthesis. She had an uncomplicated postoperative course. Follow-up examinations revealed no evidence of recurrence. Although lumbar hernia rarely results in incarceration or strangulation, early repair is necessary because of the risks of complications and the increasing difficulty in repairment as it enlarges. Surgical repair is often difficult and challenging.

A Generic Deep-Learning-Based Approach for Automated Surface Inspection.

PubMed

Ren, Ruoxu; Hung, Terence; Tan, Kay Chen

2018-03-01

Automated surface inspection (ASI) is a challenging task in industry, as collecting training dataset is usually costly and related methods are highly dataset-dependent. In this paper, a generic approach that requires small training data for ASI is proposed. First, this approach builds classifier on the features of image patches, where the features are transferred from a pretrained deep learning network. Next, pixel-wise prediction is obtained by convolving the trained classifier over input image. An experiment on three public and one industrial data set is carried out. The experiment involves two tasks: 1) image classification and 2) defect segmentation. The results of proposed algorithm are compared against several best benchmarks in literature. In the classification tasks, the proposed method improves accuracy by 0.66%-25.50%. In the segmentation tasks, the proposed method reduces error escape rates by 6.00%-19.00% in three defect types and improves accuracies by 2.29%-9.86% in all seven defect types. In addition, the proposed method achieves 0.0% error escape rate in the segmentation task of industrial data.

[Implantation of an Artificial Iris in 11 Patients].

PubMed

Kniestedt, C; Eberhard, R; Fleischhauer, J

2016-04-01

Background. Iris defects are mostly acquired after injury, or may be iatrogenic after surgical excision of iris tumours or the result of collateral trauma after anterior segment surgery. They cause severe visual disability, e.g. glare, loss of contrast sensitivity, and loss of best corrected visual acuity. The foldable Koch iris prosthesis has a customised iris design and may be used to reconstruct the anterior segment in patients with partial or complete aniridia. History and Signs. We present the surgical management and clinical course of 6 patients with traumatic iris defects, together with 3 patients with partial aniridia after cataract surgery. Cataract surgery and implantation of an artificial iris were performed in 2 female patients (3 eyes) with congenital aniridia syndrome. Therapy and Outcome. No patient exhibited complications in the postoperative course, with the exception of various intraocular pressure peaks due to secondary glaucoma, that were all corrected by medication to lower topical pressure. Conclusions. In patients with major iris defects, the artificial iris allows functionally and aesthetically satisfactory reconstruction of the anterior segment. Georg Thieme Verlag KG Stuttgart · New York.

Implementation of a General Real-Time Visual Anomaly Detection System Via Soft Computing

NASA Technical Reports Server (NTRS)

Dominguez, Jesus A.; Klinko, Steve; Ferrell, Bob; Steinrock, Todd (Technical Monitor)

2001-01-01

The intelligent visual system detects anomalies or defects in real time under normal lighting operating conditions. The application is basically a learning machine that integrates fuzzy logic (FL), artificial neural network (ANN), and generic algorithm (GA) schemes to process the image, run the learning process, and finally detect the anomalies or defects. The system acquires the image, performs segmentation to separate the object being tested from the background, preprocesses the image using fuzzy reasoning, performs the final segmentation using fuzzy reasoning techniques to retrieve regions with potential anomalies or defects, and finally retrieves them using a learning model built via ANN and GA techniques. FL provides a powerful framework for knowledge representation and overcomes uncertainty and vagueness typically found in image analysis. ANN provides learning capabilities, and GA leads to robust learning results. An application prototype currently runs on a regular PC under Windows NT, and preliminary work has been performed to build an embedded version with multiple image processors. The application prototype is being tested at the Kennedy Space Center (KSC), Florida, to visually detect anomalies along slide basket cables utilized by the astronauts to evacuate the NASA Shuttle launch pad in an emergency. The potential applications of this anomaly detection system in an open environment are quite wide. Another current, potentially viable application at NASA is in detecting anomalies of the NASA Space Shuttle Orbiter's radiator panels.

Rapid and reliable healing of critical size bone defects with genetically modified sheep muscle.

PubMed

Liu, F; Ferreira, E; Porter, R M; Glatt, V; Schinhan, M; Shen, Z; Randolph, M A; Kirker-Head, C A; Wehling, C; Vrahas, M S; Evans, C H; Wells, J W

2015-09-21

Large segmental defects in bone fail to heal and remain a clinical problem. Muscle is highly osteogenic, and preliminary data suggest that autologous muscle tissue expressing bone morphogenetic protein-2 (BMP-2) efficiently heals critical size defects in rats. Translation into possible human clinical trials requires, inter alia, demonstration of efficacy in a large animal, such as the sheep. Scale-up is fraught with numerous biological, anatomical, mechanical and structural variables, which cannot be addressed systematically because of cost and other practical issues. For this reason, we developed a translational model enabling us to isolate the biological question of whether sheep muscle, transduced with adenovirus expressing BMP-2, could heal critical size defects in vivo. Initial experiments in athymic rats noted strong healing in only about one-third of animals because of unexpected immune responses to sheep antigens. For this reason, subsequent experiments were performed with Fischer rats under transient immunosuppression. Such experiments confirmed remarkably rapid and reliable healing of the defects in all rats, with bridging by 2 weeks and remodelling as early as 3-4 weeks, despite BMP-2 production only in nanogram quantities and persisting for only 1-3 weeks. By 8 weeks the healed defects contained well-organised new bone with advanced neo-cortication and abundant marrow. Bone mineral content and mechanical strength were close to normal values. These data demonstrate the utility of this model when adapting this technology for bone healing in sheep, as a prelude to human clinical trials.

Automatic Fabric Defect Detection with a Multi-Scale Convolutional Denoising Autoencoder Network Model.

PubMed

Mei, Shuang; Wang, Yudan; Wen, Guojun

2018-04-02

Fabric defect detection is a necessary and essential step of quality control in the textile manufacturing industry. Traditional fabric inspections are usually performed by manual visual methods, which are low in efficiency and poor in precision for long-term industrial applications. In this paper, we propose an unsupervised learning-based automated approach to detect and localize fabric defects without any manual intervention. This approach is used to reconstruct image patches with a convolutional denoising autoencoder network at multiple Gaussian pyramid levels and to synthesize detection results from the corresponding resolution channels. The reconstruction residual of each image patch is used as the indicator for direct pixel-wise prediction. By segmenting and synthesizing the reconstruction residual map at each resolution level, the final inspection result can be generated. This newly developed method has several prominent advantages for fabric defect detection. First, it can be trained with only a small amount of defect-free samples. This is especially important for situations in which collecting large amounts of defective samples is difficult and impracticable. Second, owing to the multi-modal integration strategy, it is relatively more robust and accurate compared to general inspection methods (the results at each resolution level can be viewed as a modality). Third, according to our results, it can address multiple types of textile fabrics, from simple to more complex. Experimental results demonstrate that the proposed model is robust and yields good overall performance with high precision and acceptable recall rates.

Thrombus formation in the interrupted segment of the aorta.

PubMed

Karavelioğlu, Yusuf; Kalçık, Macit; Yetim, Mucahit; Doğan, Tolga; Gölbaşı, Zehra

2017-06-01

Interrupted aorta is a very rare heart defect in which there is a gap between the ascending and the descending thoracic aorta. It is usually associated with other cardiac anomalies, including ventricular septal defect, ductus arteriosus, and truncus arteriosus. Severe cases present with serious complications such as hypertension, heart failure, or intracranial hemorrhage. Neurological complications are very rare form of presentation and commonly associated with intracranial aneurysms. We have reported a case of interrupted aorta who presented with transient ischemic attack due to thrombus formation in the interrupted segment of the aorta. © 2017, Wiley Periodicals, Inc.

Regional glucose utilization in infarcted and remote myocardium: its relation to coronary anatomy and perfusion.

PubMed

Fragasso, G; Chierchia, S L; Landoni, C; Lucignani, G; Rossetti, E; Sciammarella, M; Vanoli, G E; Fazio, F

1998-07-01

We studied the relationship between coronary anatomy, perfusion and metabolism in myocardial segments exhibiting transient and persistent perfusion defects on stress/rest 99Tcm-MIBI single photon emission tomography in 35 patients (31 males, 4 females, mean age 56 +/- 7 years) with a previous myocardial infarction. Quantitative coronary angiography and assessment of myocardial perfusion reserve and glucose metabolism were performed within 1 week of one another. Perfusion was assessed by SPET after the intravenous injection of 740 MBq of 99Tcm-MIBI at rest and after exercise. Regional myocardial glucose metabolism was assessed by position emission tomography at rest (200 MBq of 18F-2-deoxyglucose, FDG) after an overnight fast with no glucose loading. All 35 patients exhibited persistent perfusion defects consistent with the clinically identified infarct site, and 27 (77%) also showed various degrees of within-infarct FDG uptake; 11 patients developed exercise-induced transient perfusion defects within, or in the vicinity of, 15 infarct segments and resting FDG uptake was present in 10 of these segments (67%). Five patients also showed exercise-induced transient perfusion defects in nine segments remote from the site of infarct: resting FDG uptake was present in six of these regions (67%). Finally, nine patients had increased glucose uptake in non-infarcted regions not showing transient perfusion defects upon exercise testing and perfused by coronary arteries with only minor irregularities. Our results confirm the presence of viable tissue in a large proportion of infarct sites. Moreover, FDG uptake can be seen in regions perfused by coronary arteries showing minor irregularities, not necessarily resulting in detectable transient perfusion defects on a MIBI stress scan. Since the clinical significance of such findings is not clear, further studies should be conducted to assess the long-term evolution of perfusion, function and metabolism in non-revascularized patients of those remote areas which are apparently normally perfused, but show abnormal fasting FDG uptake after myocardial infarction. Such studies may have important implications for the management of post-infarct patients, as the preservation of coronary vasodilator reserve and myocardial metabolism in remote myocardium may be seen as an additional goal in the treatment of such patients.

Analysis of the results of replacement of large bone defects in the patients who underwent segmental bone resection for tumor

NASA Astrophysics Data System (ADS)

Anastasieva, E. A.; Voropaeva, A. A.; Sadovoy, M. A.; Kirilova, I. A.

2017-09-01

The problem of large bone defects replacement, formed after segmental bone resections, remains an actual issue of modern orthopedics. It is known that the autograft is the most acceptable material for the replacement of bone tissue; however, due to its small volume and physical properties, it has limited usage. Our goal is to analyze the results of the experiments and studies on replacement of large bone defects after resection of the bone tumor. The problem is justified by the complicated osteoconduction and osteointegration; because it is proved that the reconstruction of the microcirculatory bloodstream is difficult in the presence of damage more than 4 cm2. It was revealed that using of allograft in combination with additional components is comparable in effectiveness, including long-term period, with autograft usage. It is promising to combine plastic allogenous material, capable of reconstructing defects of various configuration intraoperatively, with the necessary chemotherapy with controlled desorption to maintain effective concentration of drug.

Wood industrial application for quality control using image processing

NASA Astrophysics Data System (ADS)

Ferreira, M. J. O.; Neves, J. A. C.

1994-11-01

This paper describes an application of image processing for the furniture industry. It uses an input data, images acquired directly from wood planks where defects were previously marked by an operator. A set of image processing algorithms separates and codes each defect and detects a polygonal approach of the line representing them. For such a purpose we developed a pattern classification algorithm and a new technique of segmenting defects by carving the convex hull of the binary shape representing each isolated defect.

Inorganic-organic shape memory polymers and foams for bone defect repairs

NASA Astrophysics Data System (ADS)

Zhang, Dawei

The ultimate goal of this research was to develop a "self-fitting" shape memory polymer (SMP) scaffold for the repair of craniomaxillofacial (CMF) bone defects. CMF defects may be caused by trauma, tumor removal or congenital abnormalities and represent a major class of bone defects. Their repair with autografts is limited by availability, donor site morbidity and complex surgical procedures. In addition, shaping and positioning of these rigid grafts into irregular defects is difficult. Herein, we have developed SMP scaffolds which soften at T > ˜56 °C, allowing them to conformally fit into a bone defect. Upon cooling to body temperature, the scaffold becomes rigid and mechanically locks in place. This research was comprised of four major studies. In the first study, photocrosslinkable acrylated (AcO) SMP macromers containing a poly(epsilon-caprolactone) (PCL) segment and polydimethylsiloxane (PDMS) segments were synthesized with the general formula: AcO-PCL40-block-PDMS m-block-PCL40-OAc. By varying the PDMS segment length (m), solid SMPs with highly tunable mechanical properties and excellent shape memory abilities were prepared. In the second study, porous SMP scaffolds were fabricated based on AcO-PCL 40-block-PDMS37-block-PCL 40-OAc via a revised solvent casting particulate leaching (SCPL) method. By tailoring scaffold parameters including salt fusion, macromer concentration and salt size, scaffold properties (e.g. pore features, compressive modulus and shape memory behavior) were tuned. In the third study, porous SMP scaffolds were produced from macromers with variable PDMS segment lengths (m = 0 -- 130) via an optimized SCPL method. The impact on pore features, thermal, mechanical, and shape memory properties as well as degradation rates were investigated. In the final study, a bioactive polydopamine coating was applied onto pore surfaces of the SMP scaffold prepared from PCL diacrylate. The thin coating did not affect intrinsic bulk properties of the scaffold. However, the coating significantly increased its bioactivity, giving rise to the formation of "bone-bonding" hydroxyapatite (HAp) when exposed to simulated body fluid (SBF). It was also shown that the coating largely enhanced the scaffold's capacities to support osteoblasts adhesion, proliferation and osteogenesis. Thus, the polydopamine coating should enhance the performance of the "self-fitting" SMP scaffolds for the repair of bone defects.

Adipose-derived stem cells and BMP-2 delivery in chitosan-based 3D constructs to enhance bone regeneration in a rat mandibular defect model.

PubMed

Fan, Jiabing; Park, Hyejin; Lee, Matthew K; Bezouglaia, Olga; Fartash, Armita; Kim, Jinku; Aghaloo, Tara; Lee, Min

2014-08-01

Reconstructing segmental mandiblular defects remains a challenge in the clinic. Tissue engineering strategies provide an alternative option to resolve this problem. The objective of the present study was to determine the effects of adipose-derived stem cells (ASCs) and bone morphogenetic proteins-2 (BMP-2) in three-dimensional (3D) scaffolds on mandibular repair in a small animal model. Noggin expression levels in ASCs were downregulated by a lentiviral short hairpin RNA strategy to enhance ASC osteogenesis (ASCs(Nog-)). Chitosan (CH) and chondroitin sulfate (CS), natural polysaccharides, were fabricated into 3D porous scaffolds, which were further modified with apatite coatings for enhanced cellular responses and efficient delivery of BMP-2. The efficacy of 3D apatite-coated CH/CS scaffolds supplemented with ASCs(Nog-) and BMP-2 were evaluated in a rat critical-sized mandibular defect model. After 8 weeks postimplantation, the scaffolds treated with ASCs(Nog-) and BMP-2 significantly promoted rat mandibular regeneration as demonstrated by micro-computerized tomography, histology, and immunohistochemistry, compared with the groups treated with ASCs(Nog-) or BMP-2 alone. These results suggest that our combinatorial strategy of ASCs(Nog-)+BMP-2 in 3D apatite microenvironments can significantly promote mandibular regeneration, and these may provide a potential tissue engineering approach to repair large bony defects.

Development of Composite Scaffolds for Load Bearing Segmental Bone Defects

DTIC Science & Technology

2013-07-01

general, is that they cannot be used alone for load-bearing applications due to the brittleness (failure due to lack of plastic deformation) of...5, 61, 77, 78], microsphere sintering [77], supercritical CO2 technology [80], fused deposition modeling (FDM) [5, 6], 3D printing [5], in situ...American Ceramic Society 2006;89: 1771- 1789. [36] Vitale-Brovarone C, Miola M, Balagna C, Verné E. 3D -glass–ceramic scaffolds with antibacterial

Special distraction osteogenesis before bone grafting for alveolar cleft defects to correct maxillary deformities in patients with bilateral cleft lips and palates: distraction osteogenesis performed separately for each bone segment.

PubMed

Mitsukawa, Nobuyuki; Saiga, Atsuomi; Morishita, Tadashi; Satoh, Kaneshige

2014-07-01

Patients with bilateral cleft lips and palates have premaxillary protrusion and characteristic jaw deformities involving three-dimensional malposition of the premaxilla and bilateral maxillary bone segments. This study examined patients with bilateral cleft lips and palates who had deviation and hypoplasia of the premaxillas and bilateral maxillary segments. Before bone grafting, the patients were treated with special distraction performed separately for each bone segment using a halo-type external device. This report describes this novel treatment method which produced good results. The subjects were five patients with severe jaw deformities due to bilateral cleft lip and palate. They were treated with maxillary Le Fort I osteotomy and subsequent distraction performed separately for each bone segment using a halo device. In three of five patients, premaxillary osteotomy was not performed, and osteotomy and distraction were performed only for the right and left lateral segments with severe hypoplasia. All patients achieved distraction close to the desired amount. The widths of the alveolar clefts were narrowed, and satisfactory occlusion and maxillary arch form were achieved. After the surgery, three of five patients underwent bone grafting for bilateral alveolar cleft defects and the bone graft survival was satisfactory. This method had many benefits, including narrowing of alveolar clefts, improvement of maxillary hypoplasia, and achievement of a good maxillary arch form. In addition, subsequent bone grafting for alveolar cleft defects was beneficial, dental prostheses were unnecessary, and frequency of surgery and surgical invasiveness were reduced. This method is a good surgical procedure that should be considered for patients with bilateral cleft lips and palates who have premaxillary protrusion and hypoplasia of the right and left lateral segments. Copyright © 2013 European Association for Cranio-Maxillo-Facial Surgery. Published by Elsevier Ltd. All rights reserved.

Development of a Three-Dimensional (3D) Printed Biodegradable Cage to Convert Morselized Corticocancellous Bone Chips into a Structured Cortical Bone Graft.

PubMed

Chou, Ying-Chao; Lee, Demei; Chang, Tzu-Min; Hsu, Yung-Heng; Yu, Yi-Hsun; Liu, Shih-Jung; Ueng, Steve Wen-Neng

2016-04-20

This study aimed to develop a new biodegradable polymeric cage to convert corticocancellous bone chips into a structured strut graft for treating segmental bone defects. A total of 24 adult New Zealand white rabbits underwent a left femoral segmental bone defect creation. Twelve rabbits in group A underwent three-dimensional (3D) printed cage insertion, corticocancellous chips implantation, and Kirschner-wire (K-wire) fixation, while the other 12 rabbits in group B received bone chips implantation and K-wire fixation only. All rabbits received a one-week activity assessment and the initial image study at postoperative 1 week. The final image study was repeated at postoperative 12 or 24 weeks before the rabbit scarification procedure on schedule. After the animals were sacrificed, both femurs of all the rabbits were prepared for leg length ratios and 3-point bending tests. The rabbits in group A showed an increase of activities during the first week postoperatively and decreased anterior cortical disruptions in the postoperative image assessments. Additionally, higher leg length ratios and 3-point bending strengths demonstrated improved final bony ingrowths within the bone defects for rabbits in group A. In conclusion, through this bone graft converting technique, orthopedic surgeons can treat segmental bone defects by using bone chips but with imitate characters of structured cortical bone graft.

Development of a Three-Dimensional (3D) Printed Biodegradable Cage to Convert Morselized Corticocancellous Bone Chips into a Structured Cortical Bone Graft

PubMed Central

Chou, Ying-Chao; Lee, Demei; Chang, Tzu-Min; Hsu, Yung-Heng; Yu, Yi-Hsun; Liu, Shih-Jung; Ueng, Steve Wen-Neng

2016-01-01

This study aimed to develop a new biodegradable polymeric cage to convert corticocancellous bone chips into a structured strut graft for treating segmental bone defects. A total of 24 adult New Zealand white rabbits underwent a left femoral segmental bone defect creation. Twelve rabbits in group A underwent three-dimensional (3D) printed cage insertion, corticocancellous chips implantation, and Kirschner-wire (K-wire) fixation, while the other 12 rabbits in group B received bone chips implantation and K-wire fixation only. All rabbits received a one-week activity assessment and the initial image study at postoperative 1 week. The final image study was repeated at postoperative 12 or 24 weeks before the rabbit scarification procedure on schedule. After the animals were sacrificed, both femurs of all the rabbits were prepared for leg length ratios and 3-point bending tests. The rabbits in group A showed an increase of activities during the first week postoperatively and decreased anterior cortical disruptions in the postoperative image assessments. Additionally, higher leg length ratios and 3-point bending strengths demonstrated improved final bony ingrowths within the bone defects for rabbits in group A. In conclusion, through this bone graft converting technique, orthopedic surgeons can treat segmental bone defects by using bone chips but with imitate characters of structured cortical bone graft. PMID:27104525

Prevalence and pattern of abnormal myocardial perfusion in patients with isolated coronary artery ectasia: study by 99mTc-sestamibi radionuclide scintigraphy.

PubMed

Ismail, Ahmed M; Rayan, Mona; Adel, Amr; Demerdash, Salah; Atef, Mohamed; Abdallah, Mohamed; Nammas, Wail

2014-02-01

We explored the prevalence and pattern of abnormal myocardial perfusion in patients with isolated coronary artery ectasia (CAE), as demonstrated by (99m)Tc-sestamibi scintigraphy. Prospectively, we enrolled 35 patients with angiographically documented CAE and no significant coronary obstruction, who underwent elective coronary angiography. Patients underwent Stress-rest (99m)Tc-sestamibi scintigraphy within 4 days of coronary angiography. They were divided into 2 groups: group I: with normal perfusion scan; and group II: with reversible perfusion defects. The mean age was 49.6 ± 6.9 years; 34 (97.1 %) were males. Seventy-nine (75.2 %) arteries were affected by CAE. Among 79 arteries affected by CAE, affection was diffuse in 37 (46.8 %). Thirteen (37.1 %) patients had normal perfusion scan (group I), whereas 22 (62.9 %) had reversible perfusion defects (group II). Among 22 patients with reversible perfusion defects, 20 (90.9 %) had mild and 2 (9.1 %) had moderate ischemia. Among 49 myocardial segments with reversible perfusion defects, 22 (44.9 %) were basal, 18 (36.7 %) mid-, and 9 (18.4 %) apical segments. Diffuse CAE was significantly more prevalent in group II versus group I, in all 3 major coronary arteries (p < 0.05 for all). In patients with isolated CAE who underwent elective coronary angiography, reversible perfusion defects demonstrated by (99m)Tc-sestamibi scintigraphy were rather prevalent, mostly mild, more likely to affect the basal and mid-segments of the myocardium, and more frequently associated with diffuse ectasia.

Resonant Raman scattering of controlled molecular weight polyacetylene

NASA Astrophysics Data System (ADS)

Schen, M. A.; Chien, J. C. W.; Perrin, E.; Lefrant, S.; Mulazzi, E.

1988-12-01

Polyacetylene, (CH)x, films of 500, 5300, 10 500, and 100 000 Daltons number average molecular weights (Mn ) were synthesized using the titanium tetra-n-butoxide/triethyl aluminum-catalyst/cocatalyst system and examined using resonant Raman scattering techniques. Before isomerization, trans segments are found to exist mainly as short, isolated sequences independent of Mn. After thermal isomerization, theoretical analysis of the RRS spectra using the Brivio, Mulazzi model indicate the ratio of long trans conjugated segments (N≥30) to short trans conjugated segments (N≤30) is significantly larger for 100 000 Dalton polymer in comparison to polymer of 10 500 Mn and below. For samples below 10 500 Daltons, no clear relationship between actual polymer molecular weight and G is observed. Optimization of the isomerization conditions for 100 000 Dalton polymer results in trans-(CH)x with a G=0.80. These results suggest that not until very long molecular chains are obtained can samples composed principally of long conjugated segments be obtained. It is proposed that defects which arise during and after the polymerization limit the content of long segments. Ambient, short term oxidation of 100 000 Mn polymer shows a decrease in G from 0.80 to 0.70. Low level chain oxidation or doping is shown to preferentially occur within long conjugated segments.

Laparoscopic ureteral reimplantation with Boari flap for the management of long- segment ureteral defect: A case series with review of the literature

PubMed Central

Bansal, Ankur; Sinha, Rahul Janak; Jhanwar, Ankur; Prakash, Gaurav; Purkait, Bimalesh; Singh, Vishwajeet

2017-01-01

Objective The incidence of ureteral stricture is showing a rising trend due to increased use of laparoscopic and upper urinary tract endoscopic procedures. Boari flap is the preferred method of repairing long- segment ureteral defects of 8–12 cm. The procedure has undergone change from classical open (transperitoneal and retroperitoneal) method to laparoscopic surgery and recently robotic surgery. Laparoscopic approach is cosmetically appealing, less morbid and with shorter hospital stay. In this case series, we report our experience of performing laparoscopic ureteral reimplantation with Boari flap in 3 patients. Material and methods This prospective study was conducted between January 2011 December 2014. The patients with a long- segment ureteral defect who had undergone laparoscopic Boari flap reconstruction were included in the study. Outcome of laparoscopic ureteral reimplantation with Boari flap for the manangement of long segment ureteral defect was evaluated. Results The procedure was performed on 3 patients, and male to female ratio was 1:2. One patient had bilateral and other two patient had left ureteral stricture. The mean length of ureteral stricture was 8.6 cm (range 8.2–9.2 cm). The mean operative time was 206 min (190 to 220 min). The average estimated blood loss was 100 mL (range 90–110 mL) and mean hospital stay was 6 days (range 5 to 7 days). The mean follow up was 19 months (range 17–22 months). None of the patients experienced any complication related to the procedure in perioperative period. Conclusion Laparoscopic ureteral reimplantation with Boari flap is safe, feasible and has excellent long term results. However, the procedure is technically challenging, requires extensive experience of intracorporeal suturing. PMID:28861304

Laparoscopic ureteral reimplantation with Boari flap for the management of long- segment ureteral defect: A case series with review of the literature.

PubMed

Bansal, Ankur; Sinha, Rahul Janak; Jhanwar, Ankur; Prakash, Gaurav; Purkait, Bimalesh; Singh, Vishwajeet

2017-09-01

The incidence of ureteral stricture is showing a rising trend due to increased use of laparoscopic and upper urinary tract endoscopic procedures. Boari flap is the preferred method of repairing long- segment ureteral defects of 8-12 cm. The procedure has undergone change from classical open (transperitoneal and retroperitoneal) method to laparoscopic surgery and recently robotic surgery. Laparoscopic approach is cosmetically appealing, less morbid and with shorter hospital stay. In this case series, we report our experience of performing laparoscopic ureteral reimplantation with Boari flap in 3 patients. This prospective study was conducted between January 2011 December 2014. The patients with a long- segment ureteral defect who had undergone laparoscopic Boari flap reconstruction were included in the study. Outcome of laparoscopic ureteral reimplantation with Boari flap for the manangement of long segment ureteral defect was evaluated. The procedure was performed on 3 patients, and male to female ratio was 1:2. One patient had bilateral and other two patient had left ureteral stricture. The mean length of ureteral stricture was 8.6 cm (range 8.2-9.2 cm). The mean operative time was 206 min (190 to 220 min). The average estimated blood loss was 100 mL (range 90-110 mL) and mean hospital stay was 6 days (range 5 to 7 days). The mean follow up was 19 months (range 17-22 months). None of the patients experienced any complication related to the procedure in perioperative period. Laparoscopic ureteral reimplantation with Boari flap is safe, feasible and has excellent long term results. However, the procedure is technically challenging, requires extensive experience of intracorporeal suturing.

All Internal Segmental Bone Transport and Optional Lengthening With a Newly Developed Universal Cylinder-Kombi-Tube Module for Motorized Nails-Description of a Surgical Technique.

PubMed

Krettek, Christian; El Naga, Ashraf

2017-10-01

Segmental transport is an effective method of treatment for segmental defects, but the need for external fixation during the transport phase is a disadvantage. To avoid external fixation, we have developed a Cylinder-Kombi-Tube Segmental Transport (CKTST) module for combination with a commercially available motorized lengthening nail. This CKTST module allows for an all-internal segmental bone transport and also allows for optional lengthening if needed. The concept and surgical technique of CKTST are described and illustrated with a clinical case.

Study of mandible reconstruction using a fibula flap with application of additive manufacturing technology.

PubMed

Tsai, Ming-June; Wu, Ching-Tsai

2014-05-06

This study aimed to establish surgical guiding techniques for completing mandible lesion resection and reconstruction of the mandible defect area with fibula sections in one surgery by applying additive manufacturing technology, which can reduce the surgical duration and enhance the surgical accuracy and success rate. A computer assisted mandible reconstruction planning (CAMRP) program was used to calculate the optimal cutting length and number of fibula pieces and design the fixtures for mandible cutting, registration, and arrangement of the fibula segments. The mandible cutting and registering fixtures were then generated using an additive manufacturing system. The CAMRP calculated the optimal fibula cutting length and number of segments based on the location and length of the defective portion of the mandible. The mandible cutting jig was generated according to the boundary surface of the lesion resection on the mandible STL model. The fibular cutting fixture was based on the length of each segment, and the registered fixture was used to quickly arrange the fibula pieces into the shape of the defect area. In this study, the mandibular lesion was reconstructed using registered fibular sections in one step, and the method is very easy to perform. The application of additive manufacturing technology provided customized models and the cutting fixtures and registered fixtures, which can improve the efficiency of clinical application. This study showed that the cutting fixture helped to rapidly complete lesion resection and fibula cutting, and the registered fixture enabled arrangement of the fibula pieces and allowed completion of the mandible reconstruction in a timely manner. Our method can overcome the disadvantages of traditional surgery, which requires a long and different course of treatment and is liable to cause error. With the help of optimal cutting planning by the CAMRP and the 3D printed mandible resection jig and fibula cutting fixture, this all-in-one process of mandible reconstruction furnishes many benefits in this field by enhancing the accuracy of surgery, shortening the operation duration, reducing the surgical risk, and resulting in a better mandible appearance of the patients after surgery.

Study of mandible reconstruction using a fibula flap with application of additive manufacturing technology

PubMed Central

2014-01-01

Background This study aimed to establish surgical guiding techniques for completing mandible lesion resection and reconstruction of the mandible defect area with fibula sections in one surgery by applying additive manufacturing technology, which can reduce the surgical duration and enhance the surgical accuracy and success rate. Methods A computer assisted mandible reconstruction planning (CAMRP) program was used to calculate the optimal cutting length and number of fibula pieces and design the fixtures for mandible cutting, registration, and arrangement of the fibula segments. The mandible cutting and registering fixtures were then generated using an additive manufacturing system. The CAMRP calculated the optimal fibula cutting length and number of segments based on the location and length of the defective portion of the mandible. The mandible cutting jig was generated according to the boundary surface of the lesion resection on the mandible STL model. The fibular cutting fixture was based on the length of each segment, and the registered fixture was used to quickly arrange the fibula pieces into the shape of the defect area. In this study, the mandibular lesion was reconstructed using registered fibular sections in one step, and the method is very easy to perform. Results and conclusion The application of additive manufacturing technology provided customized models and the cutting fixtures and registered fixtures, which can improve the efficiency of clinical application. This study showed that the cutting fixture helped to rapidly complete lesion resection and fibula cutting, and the registered fixture enabled arrangement of the fibula pieces and allowed completion of the mandible reconstruction in a timely manner. Our method can overcome the disadvantages of traditional surgery, which requires a long and different course of treatment and is liable to cause error. With the help of optimal cutting planning by the CAMRP and the 3D printed mandible resection jig and fibula cutting fixture, this all-in-one process of mandible reconstruction furnishes many benefits in this field by enhancing the accuracy of surgery, shortening the operation duration, reducing the surgical risk, and resulting in a better mandible appearance of the patients after surgery. PMID:24885749

Using optical coherence tomography to rapidly phenotype and quantify congenital heart defects associated with prenatal alcohol exposure

PubMed Central

Karunamuni, Ganga; Gu, Shi; Doughman, Yong Qiu; Noonan, Amanda I.; Rollins, Andrew M.; Jenkins, Michael W.; Watanabe, Michiko

2014-01-01

Background The most commonly used method to analyze congenital heart defects involves serial sectioning and histology. However, this is often a time-consuming process where the quantification of cardiac defects can be difficult due to problems with accurate section registration. Here we demonstrate the advantages of using optical coherence tomography, a comparatively new and rising technology, to phenotype avian embryo hearts in a model of Fetal Alcohol Syndrome where a binge-like quantity of alcohol/ethanol was introduced at gastrulation. Results The rapid, consistent imaging protocols allowed for the immediate identification of cardiac anomalies, including ventricular septal defects and misaligned/missing vessels. Interventricular septum thicknesses and vessel diameters for three of the five outflow arteries were also significantly reduced. Outflow and atrio-ventricular valves were segmented using image processing software and had significantly reduced volumes compared to controls. This is the first study to our knowledge that has 3-D reconstructed the late-stage cardiac valves in precise detail in order to examine their morphology and dimensions. Conclusion We believe therefore that OCT, with its ability to rapidly image and quantify tiny embryonic structures in high resolution, will serve as an excellent and cost-effective preliminary screening tool for developmental biologists working with a variety of experimental/disease models. PMID:25546089

The Role of Three-Dimensional Scaffolds in Treating Long Bone Defects: Evidence from Preclinical and Clinical Literature-A Systematic Review.

PubMed

Roffi, Alice; Krishnakumar, Gopal Shankar; Gostynska, Natalia; Kon, Elizaveta; Candrian, Christian; Filardo, Giuseppe

2017-01-01

Long bone defects represent a clinical challenge. Bone tissue engineering (BTE) has been developed to overcome problems associated with conventional methods. The aim of this study was to assess the BTE strategies available in preclinical and clinical settings and the current evidence supporting this approach. A systematic literature screening was performed on PubMed database, searching for both preclinical (only on large animals) and clinical studies. The following string was used: "(Scaffold OR Implant) AND (Long bone defect OR segmental bone defect OR large bone defect OR bone loss defect)." The search retrieved a total of 1573 articles: 51 preclinical and 4 clinical studies were included. The great amount of preclinical papers published over the past few years showed promising findings in terms of radiological and histological evidence. Unfortunately, this in vivo situation is not reflected by a corresponding clinical impact, with few published papers, highly heterogeneous and with small patient populations. Several aspects should be further investigated to translate positive preclinical findings into clinical protocols: the identification of the best biomaterial, with both biological and biomechanical suitable properties, and the selection of the best choice between cells, GFs, or their combination through standardized models to be validated by randomized trials.

Osteogenic effect of a gastric pentadecapeptide, BPC-157, on the healing of segmental bone defect in rabbits: a comparison with bone marrow and autologous cortical bone implantation.

PubMed

Sebecić, B; Nikolić, V; Sikirić, P; Seiwerth, S; Sosa, T; Patrlj, L; Grabarević, Z; Rucman, R; Petek, M; Konjevoda, P; Jadrijević, S; Perović, D; Slaj, M

1999-03-01

Gastrectomy often results in increased likelihood of osteoporosis, metabolic aberration, and risk of fracture, and there is a need for a gastric peptide with osteogenic activity. A novel stomach pentadecapeptide, BPC-157, improves wound and fracture healing in rats in addition to having an angiogenic effect. Therefore, in the present study, using a segmental osteoperiosteal bone defect (0.8 cm, in the middle of the left radius) that remained incompletely healed in all control rabbits for 6 weeks (assessed in 2 week intervals), pentadecapeptide BPC-157 was further studied (either percutaneously given locally [10 microg/kg body weight] into the bone defect, or applied intramuscularly [intermittently, at postoperative days 7, 9, 14, and 16 at 10 microg/kg body weight] or continuously [once per day, postoperative days 7-21 at 10 microg or 10 ng/kg body weight]). For comparison, rabbits percutaneously received locally autologous bone marrow (2 mL, postoperative day 7). As standard treatment, immediately after its formation, the bone defect was filled with an autologous cortical graft. Saline-treated (2 mL intramuscularly [i.m.] and 2 mL locally into the bone defect), injured animals were used as controls. Pentadecapeptide BPC-157 significantly improved the healing of segmental bone defects. For instance, upon radiographic assessment, the callus surface, microphotodensitometry, quantitative histomorphometry (10 microg/kg body weight i.m. for 14 days), or quantitative histomorphometry (10 ng/kg body weight i.m. for 14 days) the effect of pentadecapeptide BPC-157 was shown to correspond to improvement after local application of bone marrow or autologous cortical graft. Moreover, a comparison of the number of animals with unhealed defects (all controls) or healed defects (complete bony continuity across the defect site) showed that besides pentadecapeptide intramuscular application for 14 days (i.e., local application of bone marrow or autologous cortical graft), also following other pentadecapeptide BPC-157 regimens (local application, or intermittent intramuscular administration), the number of animals with healed defect was increased. Hopefully, in the light of the suggested stomach significance for bone homeostasis, the possible relevance of this pentadecapeptide BPC-157 effect (local or intramuscular effectiveness, lack of unwanted effects) could be a basis for methods of choice in the future management of healing impairment in humans, and requires further investigation.

Improving bone repair of femoral and radial defects in rabbit by incorporating PRP into PLGA/CPC composite scaffold with unidirectional pore structure.

PubMed

He, Fupo; Chen, Yan; Li, Jiyan; Lin, Bomiao; Ouyang, Yi; Yu, Bo; Xia, Yuanyou; Yu, Bo; Ye, Jiandong

2015-04-01

In this study, a platelet-rich plasma poly(lactic-co-glycolic acid) (PRP-PLGA)/calcium phosphate cement (CPC) composite scaffold was prepared by incorporating PRP into PLGA/CPC scaffold with unidirectional pore structure, which was fabricated by the unidirectional freeze casting of CPC slurry and the following infiltration of PLGA. The results from in vitro cell experiments and in vivo implantation in femoral defects manifested that incorporation of PRP into PLGA/CPC scaffold improved in vitro cell response (cell attachment, proliferation, and differentiation), and markedly boosted bone formation, angiogenesis and material degradation. The incorporation of PRP into scaffold showed more outstanding improvement in osteogenesis as the scaffolds were used to repair the segmental radial defects, especially at the early stage. The new bone tissues grew along the unidirectional lamellar pores of scaffold. At 12 weeks postimplantation, the segmental radial defects treated with PRP-PLGA/CPC scaffold had almost recuperated, whereas treated with the scaffold without PRP was far from healed. Taken together, the PRP-PLGA/CPC scaffold with unidirectional pore structure is a promising candidate to repair bone defects at various sites. © 2014 Wiley Periodicals, Inc.

3D artificial bones for bone repair prepared by computed tomography-guided fused deposition modeling for bone repair.

PubMed

Xu, Ning; Ye, Xiaojian; Wei, Daixu; Zhong, Jian; Chen, Yuyun; Xu, Guohua; He, Dannong

2014-09-10

The medical community has expressed significant interest in the development of new types of artificial bones that mimic natural bones. In this study, computed tomography (CT)-guided fused deposition modeling (FDM) was employed to fabricate polycaprolactone (PCL)/hydroxyapatite (HA) and PCL 3D artificial bones to mimic natural goat femurs. The in vitro mechanical properties, in vitro cell biocompatibility, and in vivo performance of the artificial bones in a long load-bearing goat femur bone segmental defect model were studied. All of the results indicate that CT-guided FDM is a simple, convenient, relatively low-cost method that is suitable for fabricating natural bonelike artificial bones. Moreover, PCL/HA 3D artificial bones prepared by CT-guided FDM have more close mechanics to natural bone, good in vitro cell biocompatibility, biodegradation ability, and appropriate in vivo new bone formation ability. Therefore, PCL/HA 3D artificial bones could be potentially be of use in the treatment of patients with clinical bone defects.

[PHACES syndrome].

PubMed

Morcillo Azcárate, J; Bernabeu-Wittel, J; Fernández-Pineda, I; Conejo-Mir, M D; Tuduri Limousin, I; Aspiazu Salinas, D A; de Agustín Asensio, J C

2010-04-01

PHACES syndrome associates a segmental facial hemangioma with cerebral malformations, aortic branches/cranial arteries anomalies, cardiac defects, eye anomalies or ventral wall defects. The aim of this study is to analyze our experience with this syndrome. Retrospective study of the cases seen at our unit in the last year. We treat 4 cases; 3 girls and 1 child. Besides the segmental hemangioma they presented: 3 vascular cerebral malformations; 2 structural cardiopathies; 2 cerebral malformations, 1 microftalmia. We did not find ventral wall defects. A case received treatment with two cycles of metilprednisolone i.v. and oral prednisone, with favourable course; two cases received initial treatment with oral prednisone continued of oral propanolol in rising pattern up to 2 mg/kg/day, Obtaining both the detention of the tumour growth and regression of the lesion, with very good tolerance. A 7-year-old patient has been treated with colouring pulse laser for her residual lesions. When we see a segmental facial hemangioma we must perform a wide diagnostic study in order to discard a PHACES syndrome. Multidisciplinar approach to the patient by a wide expert's group gets an earlier diagnose and improves the outcome. Propranolol is a promising therapeutic alternative.

Sustained Release of Vancomycin from Polyurethane Scaffolds Inhibits Infection of Bone Wounds in a Rat Femoral Segmental Defect Model

DTIC Science & Technology

2010-04-09

polymethylmethacrylate bead implan- tation to conventional parenteral antibiotic therapy in infected total hip and knee arthroplasty, Clin. Orthop. Relat...Anger, J.A. Cobos, J.T. Mader, The treatment of infected nonunions with gentamicin- polymethylmethacrylate antibiotic beads, Clin. Orthop. Relat. Res...impregnated polymethylmethacrylate beads, Clin. Orthop. Relat. Res. (1992) 244–252. [12] D.K. Kuechle, G.C. Landon, D.M. Musher, P.C. Noble, Elution of

Algorithm research on infrared imaging target extraction based on GAC model

NASA Astrophysics Data System (ADS)

Li, Yingchun; Fan, Youchen; Wang, Yanqing

2016-10-01

Good target detection and tracking technique is significantly meaningful to increase infrared target detection distance and enhance resolution capacity. For the target detection problem about infrared imagining, firstly, the basic principles of level set method and GAC model are is analyzed in great detail. Secondly, "convergent force" is added according to the defect that GAC model is stagnant outside the deep concave region and cannot reach deep concave edge to build the promoted GAC model. Lastly, the self-adaptive detection method in combination of Sobel operation and GAC model is put forward by combining the advantages that subject position of the target could be detected with Sobel operator and the continuous edge of the target could be obtained through GAC model. In order to verify the effectiveness of the model, the two groups of experiments are carried out by selecting the images under different noise effects. Besides, the comparative analysis is conducted with LBF and LIF models. The experimental result shows that target could be better locked through LIF and LBF algorithms for the slight noise effect. The accuracy of segmentation is above 0.8. However, as for the strong noise effect, the target and noise couldn't be distinguished under the strong interference of GAC, LIF and LBF algorithms, thus lots of non-target parts are extracted during iterative process. The accuracy of segmentation is below 0.8. The accurate target position is extracted through the algorithm proposed in this paper. Besides, the accuracy of segmentation is above 0.8.

Structure Formation in Solutions of Rigid Polymers Undergoing a Phase Transition

DTIC Science & Technology

1987-04-01

cyclohexene dioxide (ERL-4206) - 10 g. nonenyl succinic anhydride (NSA) - 26 g. dimethyl amino ethanol ( DMAE ) - 0.4 g. After infiltration, short segments...existence of a significant number of defects within the individual microfibril. The presence of defects in the lateral packing of PBT chains is also suggested...of the D- and L- enantiomers yields a nematic phase. The ordered phases exhi- bit complex textures due to defects (disclinations) which depend on

Cerebro-costo-mandibular Syndrome

PubMed Central

McNicholl, B.; Egan-Mitchell, B.; Murray, J. P.; Doyle, J. F.; Kennedy, J. D.; Crome, L.

1970-01-01

Three sibs with a hitherto unreported syndrome are described, the main features being mental handicap, palatal defects, micrognathia, and severe costovertebral defects, involving segmentation of most ribs and fusion of their dorsal ends to the vertebral bodies. In addition one infant had hypoplasia of an elbow together with defects of sacrum and coccyx; she and one other sib had minor dental defects. The syndrome is potentially lethal in the neonatal period; one of the sibs has survived. The inheritance is probably autosomal recessive. ImagesFIG. 1FIG. 2FIG. 3FIG. 4 PMID:5427859

The influence of defects of the fatigue resistance of butt and girth welds in A106B steel

NASA Technical Reports Server (NTRS)

Leis, B. N.; Goetz, D. P.; Scott, P. M.

1986-01-01

This three-phase study was directed at developing a fitness for service defect acceptance criteria for welds with defect indications. The study focussed on A106 Gr. B steel pipe. The first phase involved a literature search and critical review to develop the preliminary acceptance criteria to the extent permitted by the data. The second phase developed data for flat plate, wall segment, and vessel specimens containing artificial or natural planar or volumetric defects. The final phase developed acceptance criteria from the test data.

Intensity compensation for on-line detection of defects on fruit

NASA Astrophysics Data System (ADS)

Wen, Zhiqing; Tao, Yang

1997-10-01

A machine-vision sorting system was developed that utilizes the difference in light reflectance of fruit surfaces to distinguish the defective and good apples. To accommodate to the spherical reflectance characteristics of fruit with curved surface like apple, a spherical transform algorithm was developed that converts the original image to a non-radiant image without losing defective segments on the fruit. To prevent high-quality dark-colored fruit form being classified into the defective class and increase the defect detection rate for light-colored fruit, an intensity compensation method using maximum propagation was used. Experimental results demonstrated the effectiveness of the method based on maximum propagation and spherical transform for on-line detection of defects on apples.

Finite element analysis on the biomechanical stability of open porous titanium scaffolds for large segmental bone defects under physiological load conditions.

PubMed

Wieding, Jan; Souffrant, Robert; Mittelmeier, Wolfram; Bader, Rainer

2013-04-01

Repairing large segmental defects in long bones caused by fracture, tumour or infection is still a challenging problem in orthopaedic surgery. Artificial materials, i.e. titanium and its alloys performed well in clinical applications, are plenary available, and can be manufactured in a wide range of scaffold designs. Although the mechanical properties are determined, studies about the biomechanical behaviour under physiological loading conditions are rare. The goal of our numerical study was to determine the suitability of open-porous titanium scaffolds to act as bone scaffolds. Hence, the mechanical stability of fourteen different scaffold designs was characterized under both axial compression and biomechanical loading within a large segmental distal femoral defect of 30mm. This defect was stabilized with an osteosynthesis plate and physiological hip reaction forces as well as additional muscle forces were implemented to the femoral bone. Material properties of titanium scaffolds were evaluated from experimental testing. Scaffold porosity was varied between 64 and 80%. Furthermore, the amount of material was reduced up to 50%. Uniaxial compression testing revealed a structural modulus for the scaffolds between 3.5GPa and 19.1GPa depending on porosity and material consumption. The biomechanical testing showed defect gap alterations between 0.03mm and 0.22mm for the applied scaffolds and 0.09mm for the intact bone. Our results revealed that minimizing the amount of material of the inner core has a smaller influence than increasing the porosity when the scaffolds are loaded under biomechanical loading. Furthermore, an advanced scaffold design was found acting similar as the intact bone. Copyright © 2012 IPEM. Published by Elsevier Ltd. All rights reserved.

Anterior segment dysgenesis correlation with epithelial-mesenchymal transition in Smad4 knockout mice.

PubMed

Li, Jing; Qin, Yu; Zhao, Fang-Kun; Wu, Di; He, Xue-Fei; Liu, Jia; Zhao, Jiang-Yue; Zhang, Jin-Song

2016-01-01

To explore the molecular mechanisms in lens development and the pathogenesis of Peters anomaly in Smad4 defective mice. Le-Cre transgenic mouse line was employed to inactivate Smad4 in the surface ectoderm selectively. Pathological techniques were used to reveal the morphological changes of the anterior segment in Smad4 defective eye. Immunohistochemical staining was employed to observe the expression of E-cadherin, N-cadherin and α-SMA in anterior segment of Smad4 defective mice and control mice at embryonic (E) day 16.5. Real-time quantitative polymerase chain reaction (qPCR) was performed to detect the expression of Snail, Zeb1, Zeb2 and Twist2 in lens of Smad4 defective mice and control mice at E16.5. Statistical evaluations were performed using the unpaired Student's t-test (two-tailed) by SPSS 11.0 software. Conditional deletion of Smad4 on eye surface ectoderm resulted in corneal dysplasia, iridocorneal angle closure, corneolenticular adhesions and cataract resembling Peters anomaly. Loss of Smad4 function inhibited E-cadherin expression in the lens epithelium cells and corneal epithelium cells in Smad4 defective eye. Expression of N-cadherin was up-regulated in corneal epithelium and corneal stroma. Both E-cadherin and N-cadherin were down-regulated at the future trabecular meshwork region in mutant eye. The qPCR results showed that the expression of Twist2 was increased significantly in the mutant lens (P<0.01). Smad4 is essential to eye development and likely a candidate pathogenic gene to Peters anomaly by regulating epithelial-mesenchymal transition. Twist2 can be regulated by Smad4 and plays an essential role in lens development.

Development of a model of the coronary arterial tree for the 4D XCAT phantom

NASA Astrophysics Data System (ADS)

Fung, George S. K.; Segars, W. Paul; Gullberg, Grant T.; Tsui, Benjamin M. W.

2011-09-01

A detailed three-dimensional (3D) model of the coronary artery tree with cardiac motion has great potential for applications in a wide variety of medical imaging research areas. In this work, we first developed a computer-generated 3D model of the coronary arterial tree for the heart in the extended cardiac-torso (XCAT) phantom, thereby creating a realistic computer model of the human anatomy. The coronary arterial tree model was based on two datasets: (1) a gated cardiac dual-source computed tomography (CT) angiographic dataset obtained from a normal human subject and (2) statistical morphometric data of porcine hearts. The initial proximal segments of the vasculature and the anatomical details of the boundaries of the ventricles were defined by segmenting the CT data. An iterative rule-based generation method was developed and applied to extend the coronary arterial tree beyond the initial proximal segments. The algorithm was governed by three factors: (1) statistical morphometric measurements of the connectivity, lengths and diameters of the arterial segments; (2) avoidance forces from other vessel segments and the boundaries of the myocardium, and (3) optimality principles which minimize the drag force at the bifurcations of the generated tree. Using this algorithm, the 3D computational model of the largest six orders of the coronary arterial tree was generated, which spread across the myocardium of the left and right ventricles. The 3D coronary arterial tree model was then extended to 4D to simulate different cardiac phases by deforming the original 3D model according to the motion vector map of the 4D cardiac model of the XCAT phantom at the corresponding phases. As a result, a detailed and realistic 4D model of the coronary arterial tree was developed for the XCAT phantom by imposing constraints of anatomical and physiological characteristics of the coronary vasculature. This new 4D coronary artery tree model provides a unique simulation tool that can be used in the development and evaluation of instrumentation and methods for imaging normal and pathological hearts with myocardial perfusion defects.

Targeted inversion and reversion of the blood coagulation factor 8 gene in human iPS cells using TALENs.

PubMed

Park, Chul-Yong; Kim, Jungeun; Kweon, Jiyeon; Son, Jeong Sang; Lee, Jae Souk; Yoo, Jeong-Eun; Cho, Sung-Rae; Kim, Jong-Hoon; Kim, Jin-Soo; Kim, Dong-Wook

2014-06-24

Hemophilia A, one of the most common genetic bleeding disorders, is caused by various mutations in the blood coagulation factor VIII (F8) gene. Among the genotypes that result in hemophilia A, two different types of chromosomal inversions that involve a portion of the F8 gene are most frequent, accounting for almost half of all severe hemophilia A cases. In this study, we used a transcription activator-like effector nuclease (TALEN) pair to invert a 140-kbp chromosomal segment that spans the portion of the F8 gene in human induced pluripotent stem cells (iPSCs) to create a hemophilia A model cell line. In addition, we reverted the inverted segment back to its normal orientation in the hemophilia model iPSCs using the same TALEN pair. Importantly, we detected the F8 mRNA in cells derived from the reverted iPSCs lines, but not in those derived from the clones with the inverted segment. Thus, we showed that TALENs can be used both for creating disease models associated with chromosomal rearrangements in iPSCs and for correcting genetic defects caused by chromosomal inversions. This strategy provides an iPSC-based novel therapeutic option for the treatment of hemophilia A and other genetic diseases caused by chromosomal inversions.

Repair of Segmental Load-Bearing Bone Defect by Autologous Mesenchymal Stem Cells and Plasma-Derived Fibrin Impregnated Ceramic Block Results in Early Recovery of Limb Function

PubMed Central

Ng, Min Hwei; Duski, Suryasmi; Tan, Kok Keong; Yusof, Mohd Reusmaazran; Low, Kiat Cheong; Mohamed Rose, Isa; Mohamed, Zahiah; Bin Saim, Aminuddin; Idrus, Ruszymah Bt Hj

2014-01-01

Calcium phosphate-based bone substitutes have not been used to repair load-bearing bone defects due to their weak mechanical property. In this study, we reevaluated the functional outcomes of combining ceramic block with osteogenic-induced mesenchymal stem cells and platelet-rich plasma (TEB) to repair critical-sized segmental tibial defect. Comparisons were made with fresh marrow-impregnated ceramic block (MIC) and partially demineralized allogeneic bone block (ALLO). Six New Zealand White female rabbits were used in each study group and three rabbits with no implants were used as negative controls. By Day 90, 4/6 rabbits in TEB group and 2/6 in ALLO and MIC groups resumed normal gait pattern. Union was achieved significantly faster in TEB group with a radiological score of 4.50 ± 0.78 versus ALLO (1.06 ± 0.32), MIC (1.28 ± 0.24), and negative controls (0). Histologically, TEB group scored the highest percentage of new bone (82% ± 5.1%) compared to ALLO (5% ± 2.5%) and MIC (26% ± 5.2%). Biomechanically, TEB-treated tibiae achieved the highest compressive strength (43.50 ± 12.72 MPa) compared to those treated with ALLO (15.15 ± 3.57 MPa) and MIC (23.28 ± 6.14 MPa). In conclusion, TEB can repair critical-sized segmental load-bearing bone defects and restore limb function. PMID:25165699

Finite Element Analysis of Osteosynthesis Screw Fixation in the Bone Stock: An Appropriate Method for Automatic Screw Modelling

PubMed Central

Wieding, Jan; Souffrant, Robert; Fritsche, Andreas; Mittelmeier, Wolfram; Bader, Rainer

2012-01-01

The use of finite element analysis (FEA) has grown to a more and more important method in the field of biomedical engineering and biomechanics. Although increased computational performance allows new ways to generate more complex biomechanical models, in the area of orthopaedic surgery, solid modelling of screws and drill holes represent a limitation of their use for individual cases and an increase of computational costs. To cope with these requirements, different methods for numerical screw modelling have therefore been investigated to improve its application diversity. Exemplarily, fixation was performed for stabilization of a large segmental femoral bone defect by an osteosynthesis plate. Three different numerical modelling techniques for implant fixation were used in this study, i.e. without screw modelling, screws as solid elements as well as screws as structural elements. The latter one offers the possibility to implement automatically generated screws with variable geometry on arbitrary FE models. Structural screws were parametrically generated by a Python script for the automatic generation in the FE-software Abaqus/CAE on both a tetrahedral and a hexahedral meshed femur. Accuracy of the FE models was confirmed by experimental testing using a composite femur with a segmental defect and an identical osteosynthesis plate for primary stabilisation with titanium screws. Both deflection of the femoral head and the gap alteration were measured with an optical measuring system with an accuracy of approximately 3 µm. For both screw modelling techniques a sufficient correlation of approximately 95% between numerical and experimental analysis was found. Furthermore, using structural elements for screw modelling the computational time could be reduced by 85% using hexahedral elements instead of tetrahedral elements for femur meshing. The automatically generated screw modelling offers a realistic simulation of the osteosynthesis fixation with screws in the adjacent bone stock and can be used for further investigations. PMID:22470474

Internal Prosthetic Replacement of Skeletal Segments Lost in Combat Related Injuries.

DTIC Science & Technology

1981-08-01

1-cm segment from the proximal third to prevent distraction of the fragments. The fiber metal segment is then placed in the appropriate defect and the...articularis genu suprema. The medial collateral ligament is sectioned through this incision and the medial meniscus removed in toto. The articular capsule...the image intensifier showed no evidence of motion. A physical therapy was instituted to mobilize and strengthen her knee. Case #11. This 52 year old

[Modified anterolateral thigh perforator flap pedicled by cross-bridge microvascular anastomosis for repairing soft tissue defects in middle and lower segments of leg].

PubMed

Yang, Lin; Liu, Hongjun; Zhang, Wenzhong; Song, Guoxun; Xia, Shicong; Zhang, Naichen; Gu, Jiaxiang; Yuan, Chaoqun

2017-10-01

To explore the effectiveness of modified anterolateral thigh perforator flap pedicled by cross-bridge microvascular anastomosis in treatment of soft tissue defects in the middle and lower segments of the leg. Between March 2011 and June 2015, 15 cases with skin and soft tissue defects in the middle and lower segments of the legs were treated. There were 9 males and 6 females, aged 22-48 years (mean, 32.6 years). Of whom, 8 patients caused by traffic accidents, 5 by machine twist, and 2 by crash injury of heavy object. The mean interval from injury to admission was 82.6 hours (range, 2 hours to 1 week). The area of defect ranged from 13 cm×9 cm to 23 cm×16 cm. After primary debridement and vaccum sealing drainage treatment, the defects were repaired with modified anterolateral thigh perforator flap pedicled by cross-bridge microvascular anastomosis. The size of flap ranged from 15 cm×10 cm to 25 cm×15 cm. The donor sites were sutured directly or repaired with the skin grafts. The pedicle division was done at 4 weeks after operation. After operation, venous crisis occurred in 1 case and distal skin necrosis in 2 cases which was healed by dressing change. The other tissue flaps survived successfully and wounds healed by first intention. All skin grafts at donor site survived after operation, and primary healing of wound was obtained. All patients were followed up 6-24 months (mean, 13 months). All flaps were characterized by soft texture, satisfactory appearance, and restoring the protective sensation. Moreover, the two-point discrimination ranged from 15 to 28 mm (mean, 19.5 mm) at 6 months after operation. The function of both lower extremities were normal without obvious contracture of scar at donor site. Modified free anterolateral thigh perforator flap, with little damage in donor site, a reliable blood supply by making a cross-bridge microvascular anastomosis with pretibial or posterior tibial blood vessel on normal leg, is a reliable alternative method for repairing soft tissue defects with the main vessels of serious injury in the middle and lower segments of the leg.

The association of human mesenchymal stem cells with BMP-7 improves bone regeneration of critical-size segmental bone defects in athymic rats.

PubMed

Burastero, Giorgio; Scarfì, Sonia; Ferraris, Chiara; Fresia, Chiara; Sessarego, Nadia; Fruscione, Floriana; Monetti, Francesco; Scarfò, Francesca; Schupbach, Peter; Podestà, Marina; Grappiolo, Guido; Zocchi, Elena

2010-07-01

Critical size segmental bone defects are still a major challenge in reconstructive orthopedic surgery. Transplantation of human mesenchymal stem cells (hMSC) has been proposed as an alternative to autogenous bone graft, as MSC can be expanded in vitro and induced to differentiate into bone-regenerating osteoblasts by several bone morphogenetic proteins (BMP). The aim of this study was to investigate whether the association of hMSC and BMP-7, with providing the necessary scaffold to fill the bone loss, improved bone regeneration in a rat model of critical size segmental bone defect, compared to treatment with either hMSC or BMP-7 and the matrix. In addition, we tested whether pre-treatment of hMSC with cyclic ADP-ribose (cADPR), an intracellular Ca2+ mobilizer previously shown to accelerate the in vitro expansion of hMSC (Scarfì S et al, Stem Cells, 2008), affected the osteoinductive capacity of the cells in vivo. X-ray analysis, performed 2, 10 and 16 weeks after transplantation, revealed a significantly higher score in the rats treated with hMSC and BMP-7 compared to controls, receiving either hMSC or BMP-7. Microtomography and histological analysis, performed 16weeks after transplantation, confirmed the improved bone regeneration in the animals treated with the association of hMSC and BMP-7 compared to controls. Pre-treatment with cADPR to stimulate hMSC proliferation in vitro did not affect the bone regenerating capacity of the cells in vivo. These results indicate that the association of in vitro expanded hMSC with BMP-7 provide a better osteoinductive graft compared to either hMSC or BMP-7 alone. Moreover, cADPR may be used to stimulate hMSC proliferation in vitro in order to reduce the time required to obtain a transplantable number of cells, with no adverse effect on the bone regenerating capacity of hMSC. 2010 Elsevier Inc. All rights reserved.

A Novel Murine Model of Established Staphylococcal Bone Infection in the Presence of a Fracture Fixation Plate to Study Therapies Utilizing Antibiotic-laden Spacers after Revision Surgery

PubMed Central

Inzana, Jason A.; Schwarz, Edward M.; Kates, Stephen L.; Awad, Hani A.

2014-01-01

Mice are the small animal model of choice in biomedical research due to the low cost and availability of genetically engineered lines. However, the devices utilized in current mouse models of implant-associated bone infection have been limited to intramedullary or trans-cortical pins, which are not amenable to treatments involving extensive debridement of a full-thickness bone loss and placement of a segmental antibiotic spacer. To overcome these limitations, we developed a clinically faithful model that utilizes a locking fracture fixation plate to enable debridement of an infected segmental bone defect (full-thickness osteotomy) during a revision surgery, and investigated the therapeutic effects of placing an antibiotic-laden spacer in the segmental bone defect. To first determine the ideal time point for revision following infection, a 0.7 mm osteotomy in the femoral mid-shaft was stabilized with a radiolucent PEEK fixation plate. The defect was inoculated with bioluminescent Staphylococcus aureus, and the infection was monitored over 14 days by bioluminescent imaging (BLI). Osteolysis and reactive bone formation were assessed by X-ray and micro-computed tomography (micro-CT). The active bacterial infection peaked by 5 days post-inoculation, however the stability of the implant fixation became compromised by 10–14 days post-inoculation due to osteolysis around the screws. Thus, day 7 was defined as the ideal time point to perform the revision surgery. During the revision surgery, the infected tissue was debrided and the osteotomy was widened to 3 mm to place a poly-methyl methacrylate spacer, with or without vancomycin. Half of the groups also received systemic vancomycin for the remaining 21 days of the study. The viable bacteria remaining at the end of the study were measured using colony forming unit assays. Volumetric bone changes (osteolysis and reactive bone formation) were directly measured using micro-CT image analysis. Mice that were treated with local or systemic vancomycin did not display gross pathology at the end of the study. While localized vancomycin delivery alone tended to decrease the bacterial burden and osteolysis, these effects were only significant when combined with systemic antibiotic therapy. This novel mouse model replicates key features of implant-associated osteomyelitis that make treatment extremely difficult, such as biofilm formation and osteolysis, and imitates the clinical practice of placing an antibiotic-laden spacer after infected tissue debridement. In addition, the model demonstrates the limitations of current PMMA spacers and could be an invaluable tool for evaluating alternative antimicrobial treatments for implant-associated bone infection. PMID:25459073

Spatial correspondence of 4D CT ventilation and SPECT pulmonary perfusion defects in patients with malignant airway stenosis

NASA Astrophysics Data System (ADS)

Castillo, Richard; Castillo, Edward; McCurdy, Matthew; Gomez, Daniel R.; Block, Alec M.; Bergsma, Derek; Joy, Sarah; Guerrero, Thomas

2012-04-01

To determine the spatial overlap agreement between four-dimensional computed tomography (4D CT) ventilation and single photon emission computed tomography (SPECT) perfusion hypo-functioning pulmonary defect regions in a patient population with malignant airway stenosis. Treatment planning 4D CT images were obtained retrospectively for ten lung cancer patients with radiographically demonstrated airway obstruction due to gross tumor volume. Each patient also received a SPECT perfusion study within one week of the planning 4D CT, and prior to the initiation of treatment. Deformable image registration was used to map corresponding lung tissue elements between the extreme component phase images, from which quantitative three-dimensional (3D) images representing the local pulmonary specific ventilation were constructed. Semi-automated segmentation of the percentile perfusion distribution was performed to identify regional defects distal to the known obstructing lesion. Semi-automated segmentation was similarly performed by multiple observers to delineate corresponding defect regions depicted on 4D CT ventilation. Normalized Dice similarity coefficient (NDSC) indices were determined for each observer between SPECT perfusion and 4D CT ventilation defect regions to assess spatial overlap agreement. Tidal volumes determined from 4D CT ventilation were evaluated versus measurements obtained from lung parenchyma segmentation. Linear regression resulted in a linear fit with slope = 1.01 (R2 = 0.99). Respective values for the average DSC, NDSC1 mm and NDSC2 mm for all cases and multiple observers were 0.78, 0.88 and 0.99, indicating that, on average, spatial overlap agreement between ventilation and perfusion defect regions was comparable to the threshold for agreement within 1-2 mm uncertainty. Corresponding coefficients of variation for all metrics were similarly in the range: 0.10%-19%. This study is the first to quantitatively assess 3D spatial overlap agreement between clinically acquired SPECT perfusion and specific ventilation from 4D CT. Results suggest high correlation between methods within the sub-population of lung cancer patients with malignant airway stenosis.

Ultrafast exciton migration in an HJ-aggregate: Potential surfaces and quantum dynamics

NASA Astrophysics Data System (ADS)

Binder, Robert; Polkehn, Matthias; Ma, Tianji; Burghardt, Irene

2017-01-01

Quantum dynamical and electronic structure calculations are combined to investigate the mechanism of exciton migration in an oligothiophene HJ aggregate, i.e., a combination of oligomer chains (J-type aggregates) and stacked aggregates of such chains (H-type aggregates). To this end, a Frenkel exciton model is parametrized by a recently introduced procedure [Binder et al., J. Chem. Phys. 141, 014101 (2014)] which uses oligomer excited-state calculations to perform an exact, point-wise mapping of coupled potential energy surfaces to an effective Frenkel model. Based upon this parametrization, the Multi-Layer Multi-Configuration Time-Dependent Hartree (ML-MCTDH) method is employed to investigate ultrafast dynamics of exciton transfer in a small, asymmetric HJ aggregate model composed of 30 sites and 30 active modes. For a partially delocalized initial condition, it is shown that a torsional defect confines the trapped initial exciton, and planarization induces an ultrafast resonant transition between an HJ-aggregated segment and a covalently bound "dangling chain" end. This model is a minimal realization of experimentally investigated mixed systems exhibiting ultrafast exciton transfer between aggregated, highly planarized chains and neighboring disordered segments.

Improving Bone Formation in a Rat Femur Segmental Defect by Controlling Bone Morphogenetic Protein-2 Release

DTIC Science & Technology

2011-04-01

tissue and polymer: mineralized tissue stained dark green, osteoid and collagen bright red, soft tissue pink to light green, and erythrocytes bright...of bone, soft tissue , and polymer, high-resolution digital images were acquired at 1.25 · or 20 · . The area of interest comprising the bone defect...bone, soft tissue , and polymer (when present) within the defect were quantified using Metamorph software (Molecular Devices, Inc.) and were calculated

Mesodermal retinoic acid signaling regulates endothelial cell coalescence in caudal pharyngeal arch artery vasculogenesis

PubMed Central

Li, Peng; Pashmforoush, Mohammad; Sucov, Henry M.

2011-01-01

Disruption of retinoic acid signaling causes a variety of pharyngeal arch artery and great vessel defects, as well as malformations in many other tissues, including those derived from the pharyngeal endoderm. Previous studies implied that arch artery defects in the context of defective RA signaling occur secondary to pharyngeal pouch segmentation defects, although this model has never been experimentally verified. In this study, we examined arch artery morphogenesis during mouse development, and the role of RA in this process. We show in normal embryos that the arch arteries form by vasculogenic differentiation of pharyngeal mesoderm. Using various genetic backgrounds and tissue-specific mutation approaches, we segregate pharyngeal arch artery and pharyngeal pouch defects in RA receptor mutants, and show that RA signal transduction only in pharyngeal mesoderm is required for arch artery formation. RA does not control pharyngeal mesodermal differentiation to endothelium, but instead promotes the aggregation of endothelial cells into nascent vessels. Expression of VE-cadherin was substantially reduced in RAR mutants, and this deficiency may underlie the arch artery defects. The consequences of disrupted mesodermal and endodermal RA signaling were restricted to the 4th and 6th arch arteries and to the 4th pharyngeal pouch, respectively, suggesting that different regulatory mechanisms control the formation of the more anterior arch arteries and pouches. PMID:22040871

Computed tomography arterial portography for assessment of portal vein injury after blunt hepatic trauma.

PubMed

Fu, Chen Ju; Wong, Yon Cheong; Tsang, Yuk Ming; Wang, Li Jen; Chen, Huan Wu; Ku, Yi Kang; Wu, Cheng Hsien; Chen, Huan Wen; Kang, Shih Ching

2015-01-01

Intrahepatic portal vein injuries secondary to blunt abdominal trauma are difficult to diagnose and can result in insidious bleeding. We aimed to compare computed tomography arterial portography (CTAP), reperfusion CTAP (rCTAP), and conventional computed tomography (CT) for diagnosing portal vein injuries after blunt hepatic trauma. Patients with blunt hepatic trauma, who were eligible for nonoperative management, underwent CTAP, rCTAP, and CT. The number and size of perfusion defects observed using the three methods were compared. A total of 13 patients (seven males/six females) with a mean age of 34.5±14.1 years were included in the study. A total of 36 hepatic segments had perfusion defects on rCTAP and CT, while there were 47 hepatic segments with perfusion defects on CTAP. The size of perfusion defects on CT (239 cm3; interquartile range [IQR]: 129.5, 309.5) and rCTAP (238 cm3; IQR: 129.5, 310.5) were significantly smaller compared with CTAP (291 cm3; IQR: 136, 371) (both, P = 0.002). Perfusion defects measured by CTAP were significantly greater than those determined by either rCTAP or CT in cases of blunt hepatic trauma. This finding suggests that CTAP is superior to rCTAP and CT in evaluating portal vein injuries after blunt liver trauma.

7 CFR 51.1175 - Classification of defects.

Code of Federal Regulations, 2012 CFR

2012-01-01

... STANDARDS) United States Standards for Grades of Florida Oranges and Tangelos Definitions § 51.1175... segments more than 1/4 inch (6.4 mm) at stem end, or the equivalent of this amount, by volume, when occurring in other portions of the fruit Affecting all segments more than 1/2 inch (12.7 mm) at stem end, or...

7 CFR 51.1175 - Classification of defects.

Code of Federal Regulations, 2011 CFR

2011-01-01

... STANDARDS) United States Standards for Grades of Florida Oranges and Tangelos Definitions § 51.1175... segments more than 1/4 inch (6.4 mm) at stem end, or the equivalent of this amount, by volume, when occurring in other portions of the fruit Affecting all segments more than 1/2 inch (12.7 mm) at stem end, or...

7 CFR 51.1175 - Classification of defects.

Code of Federal Regulations, 2014 CFR

2014-01-01

... Definitions § 51.1175 Classification of defects. Table I Factor Injury Damage Serious damage Very serious... mushy condition Affecting all segments more than 1/4 inch (6.4 mm) at stem end, or the equivalent of... 1/2 inch (12.7 mm) at stem end, or the equivalent of this amount, by volume, when occurring in other...

7 CFR 51.784 - Classification of defects.

Code of Federal Regulations, 2014 CFR

2014-01-01

... Definitions § 51.784 Classification of defects. Table I Factor Injury Damage Serious damage Very serious.../4 inch (6.4 mm) at stem end, or the equivalent of this amount, by volume, when occurring in other portions of the fruit Affecting all segments more than 1/2 inch (12.7 mm) at stem end, or the equivalent of...

7 CFR 51.784 - Classification of defects.

Code of Federal Regulations, 2013 CFR

2013-01-01

... Definitions § 51.784 Classification of defects. Table I Factor Injury Damage Serious damage Very serious.../4 inch (6.4 mm) at stem end, or the equivalent of this amount, by volume, when occurring in other portions of the fruit Affecting all segments more than 1/2 inch (12.7 mm) at stem end, or the equivalent of...

7 CFR 51.1175 - Classification of defects.

Code of Federal Regulations, 2013 CFR

2013-01-01

... Definitions § 51.1175 Classification of defects. Table I Factor Injury Damage Serious damage Very serious... mushy condition Affecting all segments more than 1/4 inch (6.4 mm) at stem end, or the equivalent of... 1/2 inch (12.7 mm) at stem end, or the equivalent of this amount, by volume, when occurring in other...

Unilateral advancement of the maxillary minor segment by distraction osteogenesis in patients with repaired unilateral cleft lip and palate: report of two cases.

PubMed

Kuroe, Kazuto; Iino, Shoichiro; Shomura, Kenji; Okubo, Akiro; Sugihara, Kazumasa; Ito, Gakuji

2003-05-01

Collapse of the maxillary minor segment with lateral crossbite is a common feature in patients with repaired unilateral cleft lip/palate because of maxillary alveolar bony defect and palatal scar tissue. Distraction osteogenesis (DOG) is an effective technique of lengthening and augmentation for bone and gingiva. This case report describes the effects of unilateral advancement of the maxillary minor segment by DOG in two patients with the repaired unilateral cleft lip/palate.

Utilizing Three-Dimensional Printing Technology to Assess the Feasibility of High-Fidelity Synthetic Ventricular Septal Defect Models for Simulation in Medical Education.

PubMed

Costello, John P; Olivieri, Laura J; Krieger, Axel; Thabit, Omar; Marshall, M Blair; Yoo, Shi-Joon; Kim, Peter C; Jonas, Richard A; Nath, Dilip S

2014-07-01

The current educational approach for teaching congenital heart disease (CHD) anatomy to students involves instructional tools and techniques that have significant limitations. This study sought to assess the feasibility of utilizing present-day three-dimensional (3D) printing technology to create high-fidelity synthetic heart models with ventricular septal defect (VSD) lesions and applying these models to a novel, simulation-based educational curriculum for premedical and medical students. Archived, de-identified magnetic resonance images of five common VSD subtypes were obtained. These cardiac images were then segmented and built into 3D computer-aided design models using Mimics Innovation Suite software. An Objet500 Connex 3D printer was subsequently utilized to print a high-fidelity heart model for each VSD subtype. Next, a simulation-based educational curriculum using these heart models was developed and implemented in the instruction of 29 premedical and medical students. Assessment of this curriculum was undertaken with Likert-type questionnaires. High-fidelity VSD models were successfully created utilizing magnetic resonance imaging data and 3D printing. Following instruction with these high-fidelity models, all students reported significant improvement in knowledge acquisition (P < .0001), knowledge reporting (P < .0001), and structural conceptualization (P < .0001) of VSDs. It is feasible to use present-day 3D printing technology to create high-fidelity heart models with complex intracardiac defects. Furthermore, this tool forms the foundation for an innovative, simulation-based educational approach to teach students about CHD and creates a novel opportunity to stimulate their interest in this field. © The Author(s) 2014.

Three-Dimensional Magnetic Resonance Imaging Quantification of Glenoid Bone Loss Is Equivalent to 3-Dimensional Computed Tomography Quantification: Cadaveric Study.

PubMed

Yanke, Adam B; Shin, Jason J; Pearson, Ian; Bach, Bernard R; Romeo, Anthony A; Cole, Brian J; Verma, Nikhil N

2017-04-01

To assess the ability of 3-dimensional (3D) magnetic resonance imaging (MRI, 1.5 and 3 tesla [T]) to quantify glenoid bone loss in a cadaveric model compared with the current gold standard, 3D computed tomography (CT). Six cadaveric shoulders were used to create a bone loss model, leaving the surrounding soft tissues intact. The anteroposterior (AP) dimension of the glenoid was measured at the glenoid equator and after soft tissue layer closure the specimen underwent scanning (CT, 1.5-T MRI, and 3-T MRI) with the following methods (0%, 10%, and 25% defect by area). Raw axial data from the scans were segmented using manual mask manipulation for bone and reconstructed using Mimics software to obtain a 3D en face glenoid view. Using calibrated Digital Imaging and Communications in Medicine images, the diameter of the glenoid at the equator and the area of the glenoid defect was measured on all imaging modalities. In specimens with 10% or 25% defects, no difference was detected between imaging modalities when comparing the measured defect size (10% defect P = .27, 25% defect P = .73). All 3 modalities demonstrated a strong correlation with the actual defect size (CT, ρ = .97; 1.5-T MRI, ρ = .93; 3-T MRI, ρ = .92, P < .0001). When looking at the absolute difference between the actual and measured defect area, no significance was noted between imaging modalities (10% defect P = .34, 25% defect P = .47). The error of 3-T 3D MRI increased with increasing defect size (P = .02). Both 1.5- and 3-T-based 3D MRI reconstructions of glenoid bone loss correlate with measurements from 3D CT scan data and actual defect size in a cadaveric model. Regardless of imaging modality, the error in bone loss measurement tends to increase with increased defect size. Use of 3D MRI in the setting of shoulder instability could obviate the need for CT scans. The goal of our work was to develop a reproducible method of determining glenoid bone loss from 3D MRI data and hence eliminate the need for CT scans in this setting. This will lead to decreased cost of care as well as decreased radiation exposure to patients. The long-term goal is a fully automated system that is as approachable for clinicians as current 3D CT technology. Copyright © 2016 Arthroscopy Association of North America. Published by Elsevier Inc. All rights reserved.

Numerical simulation of fluid field and in vitro three-dimensional fabrication of tissue-engineered bones in a rotating bioreactor and in vivo implantation for repairing segmental bone defects.

PubMed

Song, Kedong; Wang, Hai; Zhang, Bowen; Lim, Mayasari; Liu, Yingchao; Liu, Tianqing

2013-03-01

In this paper, two-dimensional flow field simulation was conducted to determine shear stresses and velocity profiles for bone tissue engineering in a rotating wall vessel bioreactor (RWVB). In addition, in vitro three-dimensional fabrication of tissue-engineered bones was carried out in optimized bioreactor conditions, and in vivo implantation using fabricated bones was performed for segmental bone defects of Zelanian rabbits. The distribution of dynamic pressure, total pressure, shear stress, and velocity within the culture chamber was calculated for different scaffold locations. According to the simulation results, the dynamic pressure, velocity, and shear stress around the surface of cell-scaffold construction periodically changed at different locations of the RWVB, which could result in periodical stress stimulation for fabricated tissue constructs. However, overall shear stresses were relatively low, and the fluid velocities were uniform in the bioreactor. Our in vitro experiments showed that the number of cells cultured in the RWVB was five times higher than those cultured in a T-flask. The tissue-engineered bones grew very well in the RWVB. This study demonstrates that stress stimulation in an RWVB can be beneficial for cell/bio-derived bone constructs fabricated in an RWVB, with an application for repairing segmental bone defects.

Planning of skull reconstruction based on a statistical shape model combined with geometric morphometrics.

PubMed

Fuessinger, Marc Anton; Schwarz, Steffen; Cornelius, Carl-Peter; Metzger, Marc Christian; Ellis, Edward; Probst, Florian; Semper-Hogg, Wiebke; Gass, Mathieu; Schlager, Stefan

2018-04-01

Virtual reconstruction of large cranial defects is still a challenging task. The current reconstruction procedures depend on the surgeon's experience and skills in planning the reconstruction based on mirroring and manual adaptation. The aim of this study is to propose and evaluate a computer-based approach employing a statistical shape model (SSM) of the cranial vault. An SSM was created based on 131 CT scans of pathologically unaffected adult crania. After segmentation, the resulting surface mesh of one patient was established as template and subsequently registered to the entire sample. Using the registered surface meshes, an SSM was generated capturing the shape variability of the cranial vault. The knowledge about this shape variation in healthy patients was used to estimate the missing parts. The accuracy of the reconstruction was evaluated by using 31 CT scans not included in the SSM. Both unilateral and bilateral bony defects were created on each skull. The reconstruction was performed using the current gold standard of mirroring the intact to the affected side, and the result was compared to the outcome of our proposed SSM-driven method. The accuracy of the reconstruction was determined by calculating the distances to the corresponding parts on the intact skull. While unilateral defects could be reconstructed with both methods, the reconstruction of bilateral defects was, for obvious reasons, only possible employing the SSM-based method. Comparing all groups, the analysis shows a significantly higher precision of the SSM group, with a mean error of 0.47 mm compared to the mirroring group which exhibited a mean error of 1.13 mm. Reconstructions of bilateral defects yielded only slightly higher estimation errors than those of unilateral defects. The presented computer-based approach using SSM is a precise and simple tool in the field of computer-assisted surgery. It helps to reconstruct large-size defects of the skull considering the natural asymmetry of the cranium and is not limited to unilateral defects.

Ultrasonic Welded Resorbable Mesh (SonicWeld Rx System) in Reconstruction of Segmental Mandibular Defects: Technical Note and Report of 2 Cases.

PubMed

Shanti, Rabie M; Yampolsky, Andrew; Milles, Maano; Braidy, Hani

2015-11-01

The present report describes 2 patients who underwent mandibular reconstruction after segmental mandibulectomy for benign pathology. The potential of an ultrasonic-aided biodegradable system for containment of a nonvascularized bone graft is discussed. Copyright © 2015 American Association of Oral and Maxillofacial Surgeons. Published by Elsevier Inc. All rights reserved.

Myocardial perfusion abnormalities in asymptomatic patients with systemic lupus erythematosus

DOE Office of Scientific and Technical Information (OSTI.GOV)

Hosenpud, J.D.; Montanaro, A.; Hart, M.V.

1984-08-01

Accelerated coronary artery disease and myocardial infarction in young patients with systemic lupus erythematosus is well documented; however, the prevalence of coronary involvement is unknown. Accordingly, 26 patients with systemic lupus were selected irrespective of previous cardiac history to undergo exercise thallium-201 cardiac scintigraphy. Segmental perfusion abnormalities were present in 10 of the 26 studies (38.5 percent). Five patients had reversible defects suggesting ischemia, four patients had persistent defects consistent with scar, and one patient had both reversible and persistent defects in two areas. There was no correlation between positive thallium results and duration of disease, amount of corticosteroid treatment,more » major organ system involvement or age. Only a history of pericarditis appeared to be associated with positive thallium-201 results (p less than 0.05). It is concluded that segmental myocardial perfusion abnormalities are common in patients with systemic lupus erythematosus. Whether this reflects large-vessel coronary disease or small-vessel abnormalities remains to be determined.« less

Surgical repair of sciatic nerve traumatic rupture: technical considerations and approaches.

PubMed

Abou-Al-Shaar, Hussam; Yoon, Nam; Mahan, Mark A

2018-01-01

Traumatic proximal sciatic nerve rupture poses surgical repair dilemmas. Disruption often causes a large nerve gap after proximal neuroma and distal scar removal. Also, autologous graft material to bridge the segmental defect may be insufficient, given the sciatic nerve diameter. The authors utilized knee flexion to allow single neurorrhaphy repair of a large sciatic nerve defect, bringing healthy proximal stump to healthy distal segment. To avoid aberrant regeneration, the authors split the sciatic nerve into common peroneal and tibial divisions. After 3 months, the patient can fully extend the knee and has evidence of distal regeneration and nerve continuity without substantial injury. The video can be found here: https://youtu.be/lsezRT5I8MU .

Biomechanical Analysis of a Novel Intercalary Prosthesis for Humeral Diaphyseal Segmental Defect Reconstruction.

PubMed

Zhao, Li-Ming; Tian, Dong-Mu; Wei, Yue; Zhang, Jun-Hui; Di, Zheng-Lin; He, Zhi-Yong; Hu, Yong-Cheng

2018-02-01

To study the biomechanical properties of a novel modular intercalary prosthesis for humeral diaphyseal segmental defect reconstruction, to establish valid finite element humerus and prosthesis models, and to analyze the biomechanical differences in modular intercalary prostheses with or without plate fixation. Three groups were set up to compare the performance of the prosthesis: intact humerus, humerus-prosthesis and humerus-prosthesis-plate. The models of the three groups were transferred to finite element software. Boundary conditions, material properties, and mesh generation were set up for both the prosthesis and the humerus. In addition, 100 N or 2 N.m torsion was loaded to the elbow joint surface with the glenohumeral joint surface fixed. Humeral finite element models were established according to CT scans of the cadaveric bone; reverse engineering software Geomagic was used in this procedure. Components of prosthetic models were established using 3-D modeling software Solidworks. To verify the finite element models, the in vitro tests were simulated using a mechanical testing machine (Bionix; MTS Systems Corporation, USA). Starting with a 50 N preload, the specimen was subjected to 5 times tensile (300 N) and torsional (5 N.m) strength; interval time was 30 min to allow full recovery for the next specimen load. Axial tensile and torsional loads were applied to the elbow joint surface to simulate lifting heavy objects or twisting something, with the glenohumeral joint surface fixed. Stress distribution on the humerus did not change its tendency notably after reconstruction by intercalary prosthesis whether with or without a plate. The special design which included a plate and prosthesis effectively diminished stress on the stem where aseptic loosening often takes place. Stress distribution major concentrate upon two stems without plate addition, maximum stress on proximal and distal stem respectively diminish 27.37% and 13.23% under tension, 10.66% and 11.16% under torsion after plate allied. The novel intercalary prosthesis has excellent ability to reconstruct humeral diaphyseal defects. The accessory fixation system, which included a plate and prosthesis, improved the rigidity of anti-tension and anti-torsion, and diminished the risk of prosthetic loosening and dislocation. A finite element analysis is a kind of convenient and practicable method to be used as the confirmation of experimental biomechanics study. © 2018 Chinese Orthopaedic Association and John Wiley & Sons Australia, Ltd.

A Versatile Model of Open-fracture Infection: a Contaminated Segmental Rat Femur Defect

DTIC Science & Technology

2014-06-01

has the effect of introducing an implant to lower the bacte- rial inoculum required for infection.5 A 6 mm critical defect is then created in the mid...103 1 × 104 1 × 105 Bone mean 0 7.21 × 104 7.83 × 105 1.11 × 105 1.51 × 105 Bone SEM 0 4.40 × 104 1.35 × 105 1.92 × 104 1.95 × 104 Implant mean 0 9.82...104 1.65 × 105 2.58 × 104 5.11 × 104 Implant SEM 0 5.10 × 104 1.61 × 105 3.16 × 103 9.11 × 103 12 8 4 4 3 6 6 0 0 Pr op or tio n of s am p le s w

Context-based automated defect classification system using multiple morphological masks

DOEpatents

Gleason, Shaun S.; Hunt, Martin A.; Sari-Sarraf, Hamed

2002-01-01

Automatic detection of defects during the fabrication of semiconductor wafers is largely automated, but the classification of those defects is still performed manually by technicians. This invention includes novel digital image analysis techniques that generate unique feature vector descriptions of semiconductor defects as well as classifiers that use these descriptions to automatically categorize the defects into one of a set of pre-defined classes. Feature extraction techniques based on multiple-focus images, multiple-defect mask images, and segmented semiconductor wafer images are used to create unique feature-based descriptions of the semiconductor defects. These feature-based defect descriptions are subsequently classified by a defect classifier into categories that depend on defect characteristics and defect contextual information, that is, the semiconductor process layer(s) with which the defect comes in contact. At the heart of the system is a knowledge database that stores and distributes historical semiconductor wafer and defect data to guide the feature extraction and classification processes. In summary, this invention takes as its input a set of images containing semiconductor defect information, and generates as its output a classification for the defect that describes not only the defect itself, but also the location of that defect with respect to the semiconductor process layers.

Segmental transport after unreamed intramedullary nailing. Preliminary report of a "Monorail" system.

PubMed

Raschke, M J; Mann, J W; Oedekoven, G; Claudi, B F

1992-09-01

The Ilizarov method of segmental bone transport has been shown to be an alternative to more conventional treatments of posttraumatic bony defects. After extensive clinical experience with the unreamed tibial nail in open fractures up to Grade IIIb, a new monorail fixation system for callus distraction and segmental bone transport was devised. This Monorail system is composed of an unreamed intramedullary (IM) nail and a unilateral AO distraction device. The new fixation method and the preliminary clinical experience are reported here. Four patients who previously sustained Grades II-IIIb open tibial fractures had an average bony defect of 9 cm. Two patients had previous bony infections. All patients had had serial debridements and myocutaneous flaps were required in three patients. An unreamed IM nail was inserted, and the transport device was applied. After an osteotomy, segmental transport was carried out until docking was achieved. The external fixator was removed after interlocking of the transported segment. The mean duration of external fixation was 17.9 days/cm and the mean period until roentgenographic consolidation of the distraction and nonunion site was 41.2 days/cm. There were two pin-tract infections but no IM infections. One nail broke after osseous consolidation of the regenerate at the distal interlocking site and required exchange. The goal of transport was achieved in all cases without angular or rotational deformity or length discrepancy. There were no neurovascular injuries.

Computed tomography arterial portography for assessment of portal vein injury after blunt hepatic trauma

PubMed Central

Fu, Chen-Ju; Wong, Yon-Cheong; Tsang, Yuk-Ming; Wang, Li-Jen; Chen, Huan-Wu; Ku, Yi-Kang; Wu, Cheng-Hsien; Chen, Huan-Wen; Kang, Shih-Ching

2015-01-01

PURPOSE Intrahepatic portal vein injuries secondary to blunt abdominal trauma are difficult to diagnose and can result in insidious bleeding. We aimed to compare computed tomography arterial portography (CTAP), reperfusion CTAP (rCTAP), and conventional computed tomography (CT) for diagnosing portal vein injuries after blunt hepatic trauma. METHODS Patients with blunt hepatic trauma, who were eligible for nonoperative management, underwent CTAP, rCTAP, and CT. The number and size of perfusion defects observed using the three methods were compared. RESULTS A total of 13 patients (seven males/six females) with a mean age of 34.5±14.1 years were included in the study. A total of 36 hepatic segments had perfusion defects on rCTAP and CT, while there were 47 hepatic segments with perfusion defects on CTAP. The size of perfusion defects on CT (239 cm3; interquartile range [IQR]: 129.5, 309.5) and rCTAP (238 cm3; IQR: 129.5, 310.5) were significantly smaller compared with CTAP (291 cm3; IQR: 136, 371) (both, P = 0.002). CONCLUSION Perfusion defects measured by CTAP were significantly greater than those determined by either rCTAP or CT in cases of blunt hepatic trauma. This finding suggests that CTAP is superior to rCTAP and CT in evaluating portal vein injuries after blunt liver trauma. PMID:26268303

Influenza Virus Reassortment Is Enhanced by Semi-infectious Particles but Can Be Suppressed by Defective Interfering Particles

PubMed Central

Tao, Hui; Steel, John; Lowen, Anice C.

2015-01-01

A high particle to infectivity ratio is a feature common to many RNA viruses, with ~90–99% of particles unable to initiate a productive infection under low multiplicity conditions. A recent publication by Brooke et al. revealed that, for influenza A virus (IAV), a proportion of these seemingly non-infectious particles are in fact semi-infectious. Semi-infectious (SI) particles deliver an incomplete set of viral genes to the cell, and therefore cannot support a full cycle of replication unless complemented through co-infection. In addition to SI particles, IAV populations often contain defective-interfering (DI) particles, which actively interfere with production of infectious progeny. With the aim of understanding the significance to viral evolution of these incomplete particles, we tested the hypothesis that SI and DI particles promote diversification through reassortment. Our approach combined computational simulations with experimental determination of infection, co-infection and reassortment levels following co-inoculation of cultured cells with two distinct influenza A/Panama/2007/99 (H3N2)-based viruses. Computational results predicted enhanced reassortment at a given % infection or multiplicity of infection with increasing semi-infectious particle content. Comparison of experimental data to the model indicated that the likelihood that a given segment is missing varies among the segments and that most particles fail to deliver ≥1 segment. To verify the prediction that SI particles augment reassortment, we performed co-infections using viruses exposed to low dose UV. As expected, the introduction of semi-infectious particles with UV-induced lesions enhanced reassortment. In contrast to SI particles, inclusion of DI particles in modeled virus populations could not account for observed reassortment outcomes. DI particles were furthermore found experimentally to suppress detectable reassortment, relative to that seen with standard virus stocks, most likely by interfering with production of infectious progeny from co-infected cells. These data indicate that semi-infectious particles increase the rate of reassortment and may therefore accelerate adaptive evolution of IAV. PMID:26440404

Determination of Isthmocele Using a Foley Catheter During Laparoscopic Repair of Cesarean Scar Defect.

PubMed

Akdemir, Ali; Sahin, Cagdas; Ari, Sabahattin Anil; Ergenoglu, Mete; Ulukus, Murat; Karadadas, Nedim

2018-01-01

To demonstrate a new technique of isthmocele repair via laparoscopic surgery. Case report (Canadian Task Force classification III). The local Ethics Committee waived the requirement for approval. Isthmocele localized at a low uterine segment is a defect of a previous caesarean scar due to poor myometrial healing after surgery [1]. This pouch accumulates menstrual bleeding, which can cause various disturbances and irregularities, including abnormal uterine bleeding, infertility, pelvic pain, and scar pregnancy [2-6]. Given the absence of a clearly defined surgical method in the literature, choosing the proper approach to treating isthmocele can be arduous. Laparoscopy provides a minimally invasive procedure in women with previous caesarean scar defects. A 28-year-old woman, gravida 2 para 2, presented with a complaint of prolonged postmenstrual bleeding for 5 years. She had undergone 2 cesarean deliveries. Transvaginal ultrasonography revealed a hypoechogenic area with menstrual blood in the anterior lower uterine segment. Magnetic resonance imaging showed an isthmocele localized at the anterior left lateral side of the uterus, with an estimated volume of approximately 12 cm 3 . After patient preparation, laparoscopy was performed. To repair the defect, the uterovesical peritoneal fold was incised and the bladder was mobilized from the lower uterine segment. During this surgery, differentiating the isthmocele from the abdomen can be challenging. Here we used a Foley catheter to identify the isthmocele. To do this, after mobilizing the bladder from the lower uterine segment, we inserted a Foley catheter into the uterine cavity through the cervical canal. We then filled the balloon of the catheter at the lower uterine segment under laparoscopic view, which allowed clear identification of the isthmocele pouch. The uterine defect was then incised. The isthmocele cavity was accessed, the margins of the pouch were debrided, and the edges were surgically reapproximated with continuous nonlocking single layer 2-0 polydioxanone sutures. We believed that single-layer suturing could provide for proper healing without necrosis due to suturation. During the procedure, the vesicouterine space was dissected without difficulty. A urine bag was collected with clear urine, and there was no gas leakage; thus, we considered a safety test for the bladder superfluous. Based on concerns about the possible increased risk of adhesions, we did not cover peritoneum over the suture. The patients experienced no associated complications, and she reported complete resolution of prolonged postmenstrual bleeding at a 3-month follow-up. Even though the literature is cloudy in this area, a laparoscopic approach to repairing an isthmocele is a safe and minimally invasive procedure. Our approach described here involves inserting a Foley catheter in the uterine cavity through the cervical canal, then filling the balloon in the lower uterine segment under laparoscopic view to identify the isthmocele. Copyright © 2017 AAGL. Published by Elsevier Inc. All rights reserved.

Prognostic value of myocardial perfusion SPECT versus exercise electrocardiography in patients with ST-segment depression on resting electrocardiography.

PubMed

De Lorenzo, Andrea; Hachamovitch, Rory; Kang, Xingping; Gransar, Heidi; Sciammarella, Maria G; Hayes, Sean W; Friedman, John D; Cohen, Ishac; Germano, Guido; Berman, Daniel S

2005-01-01

The value of exercise-induced ST-segment depression for the prognostic evaluation of patients with 1 mm of ST depression or greater on the resting electrocardiogram is controversial. Patients who underwent exercise myocardial perfusion single photon emission computed tomography (MPS) and had resting ST depression of 1 mm or greater with a nondiagnostic exercise electrocardiographic response (n = 1122) were followed up for 3.4 +/- 2.3 years. Those with paced rhythm, pre-excitation, left bundle branch block, or myocardial revascularization within the first 60 days after MPS were excluded. Additional exercise-induced ST-segment depression was considered significant if > or = 2 mm MPS was scored semiquantitatively by use of a 20-segment model of the left ventricle; the percentage of myocardium involved with stress defects (% myo) was derived by normalizing to the maximal possible score of 80. Hard events were defined as nonfatal myocardial infarction or cardiac death. A Cox analysis was used to determine independent predictors of hard events among clinical, exercise, and nuclear variables. Hard event rates increased as a function of % myo for either patients with exercise-induced ST depression (1.4%/y for normal MPS vs 4.1%/y for % myo >10%, P < .03) or those without it (0.7%/y for normal MPS vs 3.0%/y for % myo >10%, P = .0001). Age, diabetes mellitus, shortness of breath as the presenting symptom, and % myo were independent predictors of hard events. Exercise-induced ST depression was predictive of hard events only when it was 3 mm or greater. The presence and extent of perfusion defects, reflected in the % myo, had incremental prognostic value over clinical variables and also over all degrees of exercise-induced ST depression. Although MPS effectively risk-stratifies patients with resting ST depression of 1 mm or greater, the prognostic value of exercise-induced ST depression is limited in these patients, with a small added risk when severe (> or = 3 mm).

Repair of diaphyseal bone defects with calcitriol-loaded PLGA scaffolds and marrow stromal cells.

PubMed

Yoon, Sun Jung; Park, Ki Suk; Kim, Moon Suk; Rhee, John M; Khang, Gilson; Lee, Hai Bang

2007-05-01

Calcitriol (1,25(OH)2D3)-loaded porous poly(D,L-lactide-co-glycolide) (PLGA) scaffolds prepared by solvent casting/salt leaching method were used to repair a 1.5 cm diaphyseal segmental bone defect as a fully absorbable osteogenic biomaterial. The in vitro release of sulforhodamine B (SRB) from PLGA scaffold was measured using spectrophotometer, considering SRB as a model drug. The SRB released from SRB-incorporated PLGA scaffold during 3 months was with relatively low initial burst. The calcitriol-loaded PLGA scaffolds with or without marrow stromal cells (MSCs) were implanted in a critical-sized intercalated bone defect in rabbit femur. Defects were assessed by radiographs until 9 weeks. The bony union of the defect was observed only in the calcitriol-loaded groups. RT-PCR results indicated that MSCs, which were seeded into calcitriol-loaded scaffold, expressed an increased level of alkaline phosphatase, osteonectin, and type I collagen mRNA at day 10. After 2 and 4 weeks, the implanted scaffolds were evaluated by histology. New osteoid matrix and direct calcium deposits were more evident in calcitriol/PLGA/MSC group. Three-dimensional computed tomography and frontal tomographic images of repaired femur showed that normal femur anatomy had been restored with cortical bone with no implanted PLGA remnants at 20 weeks. It can be concluded that the porous calcitriol-loaded PLGA scaffold combined with MSCs may be a novel method for repairing the large loaded bone defect.

Infrared machine vision system for the automatic detection of olive fruit quality.

PubMed

Guzmán, Elena; Baeten, Vincent; Pierna, Juan Antonio Fernández; García-Mesa, José A

2013-11-15

External quality is an important factor in the extraction of olive oil and the marketing of olive fruits. The appearance and presence of external damage are factors that influence the quality of the oil extracted and the perception of consumers, determining the level of acceptance prior to purchase in the case of table olives. The aim of this paper is to report on artificial vision techniques developed for the online estimation of olive quality and to assess the effectiveness of these techniques in evaluating quality based on detecting external defects. This method of classifying olives according to the presence of defects is based on an infrared (IR) vision system. Images of defects were acquired using a digital monochrome camera with band-pass filters on near-infrared (NIR). The original images were processed using segmentation algorithms, edge detection and pixel value intensity to classify the whole fruit. The detection of the defect involved a pixel classification procedure based on nonparametric models of the healthy and defective areas of olives. Classification tests were performed on olives to assess the effectiveness of the proposed method. This research showed that the IR vision system is a useful technology for the automatic assessment of olives that has the potential for use in offline inspection and for online sorting for defects and the presence of surface damage, easily distinguishing those that do not meet minimum quality requirements. Crown Copyright © 2013 Published by Elsevier B.V. All rights reserved.

A Study of BMP-2-Loaded Bipotential Electrolytic Complex around a Biphasic Calcium Phosphate-Derived (BCP) Scaffold for Repair of Large Segmental Bone Defect

PubMed Central

Paul, Kallyanashis; Padalhin, Andrew R.; Linh, Nguyen Thuy Ba; Kim, Boram; Sarkar, Swapan Kumar; Lee, Byong Taek

2016-01-01

A bipotential polyelectrolyte complex with biphasic calcium phosphate (BCP) powder dispersion provides an excellent option for protein adsorption and cell attachment and can facilitate enhanced bone regeneration. Application of the bipotential polyelectrolyte complex embedded in a spongy scaffold for faster healing of large segmental bone defects (LSBD) can be a promising endeavor in tissue engineering application. In the present study, a hollow scaffold suitable for segmental long bone replacement was fabricated by the sponge replica method applying the microwave sintering process. The fabricated scaffold was coated with calcium alginate at the shell surface, and genipin-crosslinked chitosan with biphasic calcium phosphate (BCP) dispersion was loaded at the central hollow core. The chitosan core was subsequently loaded with BMP-2. The electrolytic complex was characterized using SEM, porosity measurement, FTIR spectroscopy and BMP-2 release for 30 days. In vitro studies such as MTT, live/dead, cell proliferation and cell differentiation were performed. The scaffold was implanted into a 12 mm critical size defect of a rabbit radius. The efficacy of this complex is evaluated through an in vivo study, one and two month post implantation. BV/TV ratio for BMP-2 loaded sample was (42±1.76) higher compared with hollow BCP scaffold (32±0.225). PMID:27711142

The Midline Protein Regulates Axon Guidance by Blocking the Reiteration of Neuroblast Rows within the Drosophila Ventral Nerve Cord

PubMed Central

Manavalan, Mary Ann; Gaziova, Ivana; Bhat, Krishna Moorthi

2013-01-01

Guiding axon growth cones towards their targets is a fundamental process that occurs in a developing nervous system. Several major signaling systems are involved in axon-guidance, and disruption of these systems causes axon-guidance defects. However, the specific role of the environment in which axons navigate in regulating axon-guidance has not been examined in detail. In Drosophila, the ventral nerve cord is divided into segments, and half-segments and the precursor neuroblasts are formed in rows and columns in individual half-segments. The row-wise expression of segment-polarity genes within the neuroectoderm provides the initial row-wise identity to neuroblasts. Here, we show that in embryos mutant for the gene midline, which encodes a T-box DNA binding protein, row-2 neuroblasts and their neuroectoderm adopt a row-5 identity. This reiteration of row-5 ultimately creates a non-permissive zone or a barrier, which prevents the extension of interneuronal longitudinal tracts along their normal anterior-posterior path. While we do not know the nature of the barrier, the axon tracts either stall when they reach this region or project across the midline or towards the periphery along this zone. Previously, we had shown that midline ensures ancestry-dependent fate specification in a neuronal lineage. These results provide the molecular basis for the axon guidance defects in midline mutants and the significance of proper specification of the environment to axon-guidance. These results also reveal the importance of segmental polarity in guiding axons from one segment to the next, and a link between establishment of broad segmental identity and axon guidance. PMID:24385932

A numerical study of defect detection in a plaster dome ceiling using structural acoustics.

PubMed

Bucaro, J A; Romano, A J; Valdivia, N; Houston, B H; Dey, S

2009-07-01

A numerical study is carried out to evaluate the effectiveness of using measured surface displacements resulting from acoustic speaker excitation to detect and localize flaws in a domed, plaster ceiling. The response of the structure to an incident acoustic pressure is obtained at four frequencies between 100 and 400 Hz using a parallel h-p structural acoustic finite element-based code. Three ceiling conditions are modeled: the pristine ceiling considered rigidly attached to the domed-shape support, partial detachment of a segment of the plaster layer from the support, and an interior pocket of plaster deconsolidation modeled as a heavy fluid. Spatial maps of the normal displacement resulting from speaker excitation are interpreted with the help of predictions based on static analysis. It is found that acoustic speaker excitation can provide displacement levels readily detected by commercially available laser Doppler vibrometer systems. Further, it is concluded that for 1 in. thick plaster layers, detachment sizes as small as 4 cm are detectable by direct observation of the measured displacement maps. Finally, spatial structure differences are observed in the displacement maps beneath the two defect types, which may provide a wavenumber-based feature useful for distinguishing plaster detachment from other defects such as deconsolidation.

Vancomycin-bearing synthetic bone graft delivers rhBMP-2 and promotes healing of critical rat femoral segmental defects.

PubMed

Skelly, Jordan D; Lange, Jeffrey; Filion, Tera M; Li, Xinning; Ayers, David C; Song, Jie

2014-12-01

Bone grafts simultaneously delivering therapeutic proteins and antibiotics may be valuable in orthopaedic trauma care. Previously, we developed a poly(2-hydroxyethyl methacrylate)-nanocrystalline hydroxyapatite (pHEMA-nHA) synthetic bone graft that, when preabsorbed with 400-ng rhBMP-2/7, facilitated the functional repair of critical-size rat femoral defects. Recently, we showed that pHEMA-nHA effectively retains/releases vancomycin and rhBMP-2 in vitro. The success of such a strategy requires that the incorporation of vancomycin does not compromise the structural integrity of the graft nor its ability to promote bone healing. (1) To evaluate the ability of pHEMA-nHA-vancomycin composites in combination with 3-µg rhBMP-2 to repair 5 mm rat femoral segmental defects, and (2) To determine if the encapsulated vancomycin impairs the graft/rhBMP-2-assisted bone repair. pHEMA-nHA-vancomycin, pHEMA-nHA, or collagen sponge control with/without 3-µg rhBMP-2 were press-fit in 5 mm femoral defects in SASCO-SD male rats (289-300 g). Histology, microcomputed tomography, and torsion testing were performed on 8- and 12-week explants to evaluate the extent and quality of repair. The effect of vancomycin on the temporal absorption of endogenous BMP-2 and stromal cell-derived factor-1 was evaluated by immunohistochemistry. These factors are important for bone healing initiation and stem cell recruitment, respectively. Partial bridging of the defect with bony callus by 12 weeks was observed with pHEMA-nHA-vancomycin without rhBMP-2 while full bridging with substantially mineralized callus and partial restoration of torsional strength was achieved with 3-µg rhBMP-2. The presence of vancomycin changed the absorption patterns of endogenous proteins on the grafts, but did not appear to substantially compromise graft healing. The composite pHEMA-nHA-vancomycin preabsorbed with 3-µg rhBMP-2 promoted repair of 5 mm rat femoral segmental defects. With the sample sizes applied, vancomycin encapsulation did not appear to have a negative effect on bone healing. pHEMA-nHA-vancomycin preabsorbed with rhBMP-2 may be useful in the repair of critical-size long bone defects prone to infections.

Dishevelled 2 is essential for cardiac outflow tract development, somite segmentation and neural tube closure.

PubMed

Hamblet, Natasha S; Lijam, Nardos; Ruiz-Lozano, Pilar; Wang, Jianbo; Yang, Yasheng; Luo, Zhenge; Mei, Lin; Chien, Kenneth R; Sussman, Daniel J; Wynshaw-Boris, Anthony

2002-12-01

The murine dishevelled 2 (Dvl2) gene is an ortholog of the Drosophila segment polarity gene Dishevelled, a member of the highly conserved Wingless/Wnt developmental pathway. Dvl2-deficient mice were produced to determine the role of Dvl2 in mammalian development. Mice containing null mutations in Dvl2 present with 50% lethality in both inbred 129S6 and in a hybrid 129S6-NIH Black Swiss background because of severe cardiovascular outflow tract defects, including double outlet right ventricle, transposition of the great arteries and persistent truncus arteriosis. The majority of the surviving Dvl2(-/-) mice were female, suggesting that penetrance was influenced by sex. Expression of Pitx2 and plexin A2 was attenuated in Dvl2 null mutants, suggesting a defect in cardiac neural crest development during outflow tract formation. In addition, approximately 90% of Dvl2(-/-) mice have vertebral and rib malformations that affect the proximal as well as the distal parts of the ribs. These skeletal abnormalities were more pronounced in mice deficient for both Dvl1 and Dvl2. Somite differentiation markers used to analyze Dvl2(-/-) and Dvl1(-/-);Dvl2(-/-) mutant embryos revealed mildly aberrant expression of Uncx4.1, delta 1 and myogenin, suggesting defects in somite segmentation. Finally, 2-3% of Dvl2(-/-) embryos displayed thoracic spina bifida, while virtually all Dvl1/2 double mutant embryos displayed craniorachishisis, a completely open neural tube from the midbrain to the tail. Thus, Dvl2 is essential for normal cardiac morphogenesis, somite segmentation and neural tube closure, and there is functional redundancy between Dvl1 and Dvl2 in some phenotypes.

Biomechanical stability of novel mechanically adapted open-porous titanium scaffolds in metatarsal bone defects of sheep.

PubMed

Wieding, Jan; Lindner, Tobias; Bergschmidt, Philipp; Bader, Rainer

2015-04-01

Open-porous titanium scaffolds for large segmental bone defects offer advantages like early weight-bearing and limited risk of implant failure. The objective of this experimental study was to determine the biomechanical behavior of novel open-porous titanium scaffolds with mechanical-adapted properties in vivo. Two types of the custom-made, open-porous scaffolds made of Ti6Al4V (Young's modulus: 6-8 GPa and different pore sizes) were implanted into a 20 mm segmental defect in the mid-diaphysis of the metatarsus of sheep, and were stabilized with an osteosynthesis plate. After 12 and 24 weeks postoperatively, torsional testing was performed on the implanted bone and compared to the contralateral non-treated side. Maximum torque, maximum angle, torsional stiffness, fracture energy, shear modulus and shear stress were investigated. Furthermore, bone mineral density (BMD) of the newly formed bone was determined. Mechanical loading capabilities for both scaffolds were similar and about 50% after 12 weeks (e.g., max. torque of approximately 20 Nm). A further increase after 24 weeks was found for most of the investigated parameters. Results for torsional stiffness and shear modulus as well as bone formation depended on the type of scaffold. Increased BMD after 24 weeks was found for one scaffold type but remained constant for the other one. The present data showed the capability of mechanically adapted open-porous titanium scaffolds to function as bone scaffolds for large segmental defects and the influence of the scaffold's stiffness. A further increase in the biomechanical stability can be assumed for longer observation periods of greater than six months. Copyright © 2014 Elsevier Ltd. All rights reserved.

Lung perfusion characteristics in pulmonary arterial hypertension (PAH) and peripheral forms of chronic thromboembolic pulmonary hypertension (pCTEPH): Dual-energy CT experience in 31 patients.

PubMed

Giordano, Jessica; Khung, Suonita; Duhamel, Alain; Hossein-Foucher, Claude; Bellèvre, Dimitri; Lamblin, Nicolas; Remy, Jacques; Remy-Jardin, Martine

2017-04-01

To compare lung perfusion in PAH and pCTEPH on dual-energy CT (DECT) examinations. Thirty-one patients with PAH (group 1; n = 19) and pCTEPH (group 2; n = 12) underwent a dual-energy chest CTA with reconstruction of diagnostic and perfusion images. Perfusion alterations were analysed at a segmental level. V/Q scintigraphy was available in 22 patients (group 1: 13/19; group 2: 9/12). CT perfusion was abnormal in 52.6 % of group 1 patients and in 100 % of group 2 patients (p = 0.0051). The patterns of perfusion alteration significantly differed between the two groups (p < 0.0001): (1) in group 1, 96.6 % of segments with abnormal perfusion showed patchy defects; (2) in group 2, the most frequent abnormalities consisted of patchy (58.5 %) and PE-type (37.5 %) defects. Paired comparison of CT perfusion and scintigraphy showed concordant findings in 76.9 % of group 1 (10/13) and 100 % of group 2 (9/9) patients, with a predominant or an exclusive patchy pattern in group 1 and a mixed pattern of abnormalities in group 2. Lung perfusion alterations at DECT are less frequent and more homogeneous in PAH than in pCTEPH, with a high level of concordant findings with V/Q scintigraphy. • Depiction of chronic pulmonary embolism exclusively located on peripheral arteries is difficult. • The main differential diagnosis of pCTEPH is PAH. • The pattern of DECT perfusion changes can help differentiate PAH and pCETPH. • In PAH, almost all segments with abnormal perfusion showed patchy defects. • In pCTEPH, patchy and PE-type defects were the most frequent abnormalities.

Haemodynamic changes in hepatocellular carcinoma and liver parenchyma under balloon occlusion of the hepatic artery.

PubMed

Sugihara, Fumie; Murata, Satoru; Ueda, Tatsuo; Yasui, Daisuke; Yamaguchi, Hidenori; Miki, Izumi; Kawamoto, Chiaki; Uchida, Eiji; Kumita, Shin-Ichiro

2017-06-01

To investigate haemodynamic changes in hepatocellular carcinoma (HCC) and liver under hepatic artery occlusion. Thirty-eight HCC nodules in 25 patients were included. Computed tomography (CT) during hepatic arteriography (CTHA) with and without balloon occlusion of the hepatic artery was performed. CT attenuation and enhancement volume of HCC and liver with and without balloon occlusion were measured on CTHA. Influence of balloon position (segmental or subsegmental branch) was evaluated based on differences in HCC-to-liver attenuation ratio (H/L ratio) and enhancement volume of HCC and liver. In the segmental group (n = 20), H/L ratio and enhancement volume of HCC and liver were significantly lower with balloon occlusion than without balloon occlusion. However, in the subsegmental group (n = 18), H/L ratio was significantly higher and liver enhancement volume was significantly lower with balloon occlusion; HCC enhancement volume was similar with and without balloon occlusion. Rate of change in H/L ratio and enhancement volume of HCC and liver were lower in the segmental group than in the subsegmental group. There were significantly more perfusion defects in HCC in the segmental group. Hepatic artery occlusion causes haemodynamic changes in HCC and liver, especially with segmental occlusion. • Hepatic artery occlusion causes haemodynamic changes in hepatocellular carcinoma and liver. • Segmental occlusion decreased rate of change in hepatocellular carcinoma-to-liver attenuation ratio. • Subsegmental occlusion increased rate of change in hepatocellular carcinoma-to-liver attenuation ratio. • Hepatic artery occlusion decreased enhancement volume of hepatocellular carcinoma and liver. • Hepatic artery occlusion causes perfusion defects in hepatocellular carcinoma.

Material Characterization and Geometric Segmentation of a Composite Structure Using Microfocus X-Ray Computed Tomography Image-Based Finite Element Modeling

NASA Technical Reports Server (NTRS)

Abdul-Aziz, Ali; Roth, D. J.; Cotton, R.; Studor, George F.; Christiansen, Eric; Young, P. C.

2011-01-01

This study utilizes microfocus x-ray computed tomography (CT) slice sets to model and characterize the damage locations and sizes in thermal protection system materials that underwent impact testing. ScanIP/FE software is used to visualize and process the slice sets, followed by mesh generation on the segmented volumetric rendering. Then, the local stress fields around several of the damaged regions are calculated for realistic mission profiles that subject the sample to extreme temperature and other severe environmental conditions. The resulting stress fields are used to quantify damage severity and make an assessment as to whether damage that did not penetrate to the base material can still result in catastrophic failure of the structure. It is expected that this study will demonstrate that finite element modeling based on an accurate three-dimensional rendered model from a series of CT slices is an essential tool to quantify the internal macroscopic defects and damage of a complex system made out of thermal protection material. Results obtained showing details of segmented images; three-dimensional volume-rendered models, finite element meshes generated, and the resulting thermomechanical stress state due to impact loading for the material are presented and discussed. Further, this study is conducted to exhibit certain high-caliber capabilities that the nondestructive evaluation (NDE) group at NASA Glenn Research Center can offer to assist in assessing the structural durability of such highly specialized materials so improvements in their performance and capacities to handle harsh operating conditions can be made.

Usefulness of automatic QT dispersion measurement for detecting exercise-induced myocardial ischemia.

PubMed

Takase, Bonpei; Masaki, Nobuyuki; Hattori, Hidemi; Ishihara, Masayuki; Kurita, Akira

2009-06-01

The electrocardiographic index of QT dispersion (QTd) is related to the occurrence of arrhythmia. In patients with suspected or known coronary artery disease, QTd may be affected by exercise. We investigated whether QTd that is automatically calculated by a newly developed computer system could be used as a marker of exercise-induced myocardial ischemia. The design of this study was prospective and observational. Eighty-three consecutive patients were enrolled in this study. Their QTd was measured at rest and after 3 min of exercise during exercise-stress Thallium-201 scintigraphy and compared with conventional ST-segment changes. The patients were classified into 4 groups (normal group, redistribution group, fixed defect group, redistribution with fixed defect group) based on the result of single photon emission computed tomography. As statistical analysis, one-way ANOVA with post-hoc Scheffe's method, receiver-operating characteristics (ROC) and multiple logistic regression analysis were performed. At rest, QTd was significantly greater (p<0.05) in the fixed defect group (52+/-21 ms) and the redistribution with fixed defect group (53+/-20 ms) than in the normal group (32+/-14 ms) and the redistribution group (31+/-16 ms). However, QTd tended to increase after exercise in the redistribution group, while QTd tended to decrease in the normal group, the fixed defect group, and the redistribution with fixed defect group (QTd after exercise, normal group, 28+/-17 ms, redistribution group, 35+/-19 ms, fixed defect group, 43+/-25 ms, redistribution with fixed defect group, 49+/-27 ms). Exercise significantly increased QTcd (RR interval-corrected QT dispersion) in the redistribution group. The best cut-off values of QTd and QTcd obtained from ROC curves for exercise-induced myocardial ischemia were 41.6 ms and 40.4 ms, respectively (Qtd--AUC 0.68, 95%CI 0.53- 0.83 and QTcd--AUC 0.67, 95%CI 0.55-0.80). Using these values as cut-off ones, QTd, QTcd, and conventional ST-segment change had comparable sensitivities and specificities for detecting exercise-induced myocardial ischemia (sensitivity - 60%, 58% and 49%, respectively;specificity - 78%, 80% and 83%, respectively). In addition, multiple logistic regression analysis showed that QTd (OR=2.01, 95%CI 1.15-4.10, p<0.05), QTcd (OR=2.12, 95% CI 1.02-4.30, p<0.05) and ST-segment change (OR=1.89, 95%CI 1.03-3.40, p<0.05), were the significantly associated with exercise-induced myocardial ischemia. QT dispersion and/or QTcd after exercise could be a useful marker for exercise-induced myocardial ischemia in routine clinical practice.

Evaluation of Osteoconductive Scaffolds in the Canine Femoral Multi-Defect Model

PubMed Central

Luangphakdy, Viviane; Walker, Esteban; Shinohara, Kentaro; Pan, Hui; Hefferan, Theresa; Bauer, Thomas W.; Stockdale, Linda; Saini, Sunil; Dadsetan, Mahrokh; Runge, M. Brett; Vasanji, Amit; Griffith, Linda; Yaszemski, Michael

2013-01-01

Treatment of large segmental bone defects remains an unsolved clinical challenge, despite a wide array of existing bone graft materials. This project was designed to rapidly assess and compare promising biodegradable osteoconductive scaffolds for use in the systematic development of new bone regeneration methodologies that combine scaffolds, sources of osteogenic cells, and bioactive scaffold modifications. Promising biomaterials and scaffold fabrication methods were identified in laboratories at Rutgers, MIT, Integra Life Sciences, and Mayo Clinic. Scaffolds were fabricated from various materials, including poly(L-lactide-co-glycolide) (PLGA), poly(L-lactide-co-ɛ-caprolactone) (PLCL), tyrosine-derived polycarbonate (TyrPC), and poly(propylene fumarate) (PPF). Highly porous three-dimensional (3D) scaffolds were fabricated by 3D printing, laser stereolithography, or solvent casting followed by porogen leaching. The canine femoral multi-defect model was used to systematically compare scaffold performance and enable selection of the most promising substrate(s) on which to add cell sourcing options and bioactive surface modifications. Mineralized cancellous allograft (MCA) was used to provide a comparative reference to the current clinical standard for osteoconductive scaffolds. Percent bone volume within the defect was assessed 4 weeks after implantation using both MicroCT and limited histomorphometry. Bone formed at the periphery of all scaffolds with varying levels of radial ingrowth. MCA produced a rapid and advanced stage of bone formation and remodeling throughout the defect in 4 weeks, greatly exceeding the performance of all polymer scaffolds. Two scaffold constructs, TyrPCPL/TCP and PPF4SLA/HAPLGA Dip, proved to be significantly better than alternative PLGA and PLCL scaffolds, justifying further development. MCA remains the current standard for osteoconductive scaffolds. PMID:23215980

Evaluation of osteoconductive scaffolds in the canine femoral multi-defect model.

PubMed

Luangphakdy, Viviane; Walker, Esteban; Shinohara, Kentaro; Pan, Hui; Hefferan, Theresa; Bauer, Thomas W; Stockdale, Linda; Saini, Sunil; Dadsetan, Mahrokh; Runge, M Brett; Vasanji, Amit; Griffith, Linda; Yaszemski, Michael; Muschler, George F

2013-03-01

Treatment of large segmental bone defects remains an unsolved clinical challenge, despite a wide array of existing bone graft materials. This project was designed to rapidly assess and compare promising biodegradable osteoconductive scaffolds for use in the systematic development of new bone regeneration methodologies that combine scaffolds, sources of osteogenic cells, and bioactive scaffold modifications. Promising biomaterials and scaffold fabrication methods were identified in laboratories at Rutgers, MIT, Integra Life Sciences, and Mayo Clinic. Scaffolds were fabricated from various materials, including poly(L-lactide-co-glycolide) (PLGA), poly(L-lactide-co-ɛ-caprolactone) (PLCL), tyrosine-derived polycarbonate (TyrPC), and poly(propylene fumarate) (PPF). Highly porous three-dimensional (3D) scaffolds were fabricated by 3D printing, laser stereolithography, or solvent casting followed by porogen leaching. The canine femoral multi-defect model was used to systematically compare scaffold performance and enable selection of the most promising substrate(s) on which to add cell sourcing options and bioactive surface modifications. Mineralized cancellous allograft (MCA) was used to provide a comparative reference to the current clinical standard for osteoconductive scaffolds. Percent bone volume within the defect was assessed 4 weeks after implantation using both MicroCT and limited histomorphometry. Bone formed at the periphery of all scaffolds with varying levels of radial ingrowth. MCA produced a rapid and advanced stage of bone formation and remodeling throughout the defect in 4 weeks, greatly exceeding the performance of all polymer scaffolds. Two scaffold constructs, TyrPC(PL)/TCP and PPF4(SLA)/HA(PLGA) (Dip), proved to be significantly better than alternative PLGA and PLCL scaffolds, justifying further development. MCA remains the current standard for osteoconductive scaffolds.

Histopathological and biomechanical evaluation of bone healing properties of DBM and DBM-G90 in a rabbit model.

PubMed

Meimandi Parizi, Abdolhamid; Oryan, Ahmad; Haddadi, Shahram; Bigham Sadegh, Amin

2015-01-01

The present study was designed to investigate the effects of DBM and DBM-G90 on bone healing in a rabbit model. Thirty male white albino rabbits were used in this study. An incision was made in all rabbits under general anesthesia directly over the radius in order to expose it. A 10-mm segmental defect was created on the middle portion of each radius. The defects of 10 rabbits (Group I) were filled with DBM Block and Strip (Zimmer, Inc., Warsaw, IN, USA), the defects of 10 rabbits (Group II) were filled with DBM soaked in G90, and the defects of 10 rabbits (Group III/control) were left empty. The rabbits were euthanized at 60 days postoperatively for histopathological and biomechanical evaluation. At the histopathologic level, the defects of the animals in the DBM and DBM-G90 groups showed more advanced healing criteria than those of the control group. In biomechanical findings, there was a statistically significant difference between the injured bones and contralateral normal bones of the control group in terms of measured strength. There was not a statistically significant difference between the treated bones of the DBM and DBM-G90 groups with contralateral normal bones, nor was there a statistically significant difference between the treated bones of the DBM and DBM-G90 groups with the treated bones of the control group, in terms of other biomechanical tests. Based on the histopathological and biomechanical findings, the DBM and DBM-G90 groups demonstrated superior osteogenic potential; however, G90 shows no superiority over DBM on bone healing.

Functional Reconstruction of a Combined Tendocutaneous Defect of the Achilles Using a Segmental Rectus Femoris Myofascial Construct: A Viable Alternative

PubMed Central

DeFazio, Michael Vincent; Han, Kevin Dong

2014-01-01

The composite anterolateral thigh flap with vascularized fascia lata has emerged as a workhorse at our institution for complex Achilles defects requiring both tendon and soft tissue reconstruction. Safe elevation of this flap, however, is occasionally challenged by absent or inadequate perforators supplying the anterolateral thigh. When discovered intraoperatively, alternative options derived from the same vascular network can be pursued. We present the case of a 74-year-old male who underwent composite Achilles defect reconstruction using a segmental rectus femoris myofascial free flap. Following graduated rehabilitation, postoperatively, the patient resumed full activity and was able to ambulate on his tip-toes. At 1-year follow-up, active total range of motion of the reconstructed ankle exceeded 85% of the unaffected side, and donor site morbidity was negligible. American Orthopaedic Foot and Ankle Society and Short Form-36 scores improved by 78.8% and 28.8%, respectively, compared to preoperative baseline assessments. Based on our findings, we advocate for use of the combined rectus femoris myofascial free flap as a rescue option for reconstructing composite Achilles tendon/posterior leg defects in the setting of inadequate anterolateral thigh perforators. To our knowledge, this is the first report to describe use of this flap for such an indication. PMID:24883281

Is Dual Semitendinosus Allograft Stronger Than Turndown for Achilles Tendon Reconstruction? An In Vitro Analysis.

PubMed

Aynardi, Michael C; Atwater, Lara C; Melvani, Roshan; Parks, Brent G; Paez, Adrian G; Miller, Stuart D

2017-10-01

Large Achilles tendon defects pose a treatment challenge. The standard treatment with a turndown flap requires a large extensile incision, puts the sural nerve at risk, and demands slow, careful rehabilitation. Dual allograft semitendinosus reconstruction is a new clinical alternative that has the theoretical advantages of a smaller incision, less dissection, and a stronger construct that may allow for faster rehabilitation. In a cadaver biomechanical model, we compared the dual allograft semitendinosus reconstruction with the myofascial turndown in terms of (1) mechanical strength and resistance to deformation and (2) failure mechanisms in reconstruction of large segmental Achilles defects. An 8-cm segmental Achilles defect was created in 18 cadaveric lower extremities, nine matched pairs without defect or previous surgery (mean age, 78.4 years; range, 60-97 years; three female and six male pairs). Femoral neck densitometry to determine bone mineral density found that all specimens except two were osteopenic or osteoporotic. Specimens in each pair were assigned to allograft or turndown reconstruction. The constructs were mounted on a load frame and differential variable reluctance transducers were applied to measure deformation. Specimens were preconditioned and then loaded axially. Tensile force and proximal and distal construct deformation were measured at clinical failure, defined as 10 mm of displacement, and at ultimate failure, defined as failure of the reconstruction. Failure mechanism was recorded. Tensile strength at time zero was higher in the allograft versus the turndown construct at clinical failure (156.9 ± 29.7 N versus 107.2 ± 20.0 N, respectively; mean difference, -49.7 N; 95% CI, -66.3 to -33.0 N; p < 0.001) and at ultimate failure (290.9 ± 83.2 N versus 140.7 ± 43.5 N, respectively; mean difference, -150.2 N; 95% CI, -202.9 to -97.6 N; p < 0.001). Distal construct deformation was lower in the turndown versus the allograft construct at clinical failure (1.6 ± 1.0 mm versus 4.7 ± 0.7 mm medially and 2.2 ± 1.0 mm versus 4.8 ± 1.1 mm laterally; p < 0.001). Semitendinosus allograft failure occurred via calcaneal bone bridge fracture in eight of nine specimens. All myofascial turndowns failed via suture pullout through the fascial tissue at its insertion. In this comparative biomechanical study, dual semitendinosus allograft reconstruction showed greater tensile strength and construct deformation compared with myofascial turndown in a cadaveric model of large Achilles tendon defects. Further study of dual semitendinosus allograft for treatment of severe Achilles tendon defects with cyclic loading and investigation of clinical results will better elucidate the clinical utility and indications for this technique.

Repair of a common bile duct defect with a decellularized ureteral graft

PubMed Central

Cheng, Yao; Xiong, Xian-Ze; Zhou, Rong-Xing; Deng, Yi-Lei; Jin, Yan-Wen; Lu, Jiong; Li, Fu-Yu; Cheng, Nan-Sheng

2016-01-01

AIM To evaluate the feasibility of repairing a common bile duct defect with a decellularized ureteral graft in a porcine model. METHODS Eighteen pigs were randomly divided into three groups. An approximately 1 cm segment of the common bile duct was excised from all the pigs. The defect was repaired using a 2 cm long decellularized ureteral graft over a T-tube (T-tube group, n = 6) or a silicone stent (stent group, n = 6). Six pigs underwent bile duct reconstruction with a graft alone (stentless group). The surviving animals were euthanized at 3 mo. Specimens of the common bile ducts were obtained for histological analysis. RESULTS The animals in the T-tube and stent groups survived until sacrifice. The blood test results were normal in both groups. The histology results showed a biliary epithelial layer covering the neo-bile duct. In contrast, all the animals in the stentless group died due to biliary peritonitis and cholangitis within two months post-surgery. Neither biliary epithelial cells nor accessory glands were observed at the graft sites in the stentless group. CONCLUSION Repair of a common bile duct defect with a decellularized ureteral graft appears to be feasible. A T-tube or intraluminal stent was necessary to reduce postoperative complications. PMID:28082809

Establishment of a preclinical ovine model for tibial segmental bone defect repair by applying bone tissue engineering strategies.

PubMed

Reichert, Johannes C; Epari, Devakara R; Wullschleger, Martin E; Saifzadeh, Siamak; Steck, Roland; Lienau, Jasmin; Sommerville, Scott; Dickinson, Ian C; Schütz, Michael A; Duda, Georg N; Hutmacher, Dietmar W

2010-02-01

Currently, well-established clinical therapeutic approaches for bone reconstruction are restricted to the transplantation of autografts and allografts, and the implantation of metal devices or ceramic-based implants to assist bone regeneration. Bone grafts possess osteoconductive and osteoinductive properties; however, they are limited in access and availability and associated with donor-site morbidity, hemorrhage, risk of infection, insufficient transplant integration, graft devitalization, and subsequent resorption resulting in decreased mechanical stability. As a result, recent research focuses on the development of alternative therapeutic concepts. The field of tissue engineering has emerged as an important approach to bone regeneration. However, bench-to-bedside translations are still infrequent as the process toward approval by regulatory bodies is protracted and costly, requiring both comprehensive in vitro and in vivo studies. The subsequent gap between research and clinical translation, hence, commercialization, is referred to as the "Valley of Death" and describes a large number of projects and/or ventures that are ceased due to a lack of funding during the transition from product/technology development to regulatory approval and subsequently commercialization. One of the greatest difficulties in bridging the Valley of Death is to develop good manufacturing processes and scalable designs and to apply these in preclinical studies. In this article, we describe part of the rationale and road map of how our multidisciplinary research team has approached the first steps to translate orthopedic bone engineering from bench to bedside by establishing a preclinical ovine critical-sized tibial segmental bone defect model, and we discuss our preliminary data relating to this decisive step.

Spine Patterning Is Guided by Segmentation of the Notochord Sheath.

PubMed

Wopat, Susan; Bagwell, Jennifer; Sumigray, Kaelyn D; Dickson, Amy L; Huitema, Leonie F A; Poss, Kenneth D; Schulte-Merker, Stefan; Bagnat, Michel

2018-02-20

The spine is a segmented axial structure made of alternating vertebral bodies (centra) and intervertebral discs (IVDs) assembled around the notochord. Here, we show that, prior to centra formation, the outer epithelial cell layer of the zebrafish notochord, the sheath, segments into alternating domains corresponding to the prospective centra and IVD areas. This process occurs sequentially in an anteroposterior direction via the activation of Notch signaling in alternating segments of the sheath, which transition from cartilaginous to mineralizing domains. Subsequently, osteoblasts are recruited to the mineralized domains of the notochord sheath to form mature centra. Tissue-specific manipulation of Notch signaling in sheath cells produces notochord segmentation defects that are mirrored in the spine. Together, our findings demonstrate that notochord sheath segmentation provides a template for vertebral patterning in the zebrafish spine. Copyright © 2018 The Author(s). Published by Elsevier Inc. All rights reserved.

The Palatal Approach to Distraction Osteogenesis of the Anterior Maxillary Alveolus.

PubMed

Bell, Robert E

2015-07-01

This report describes the palatal approach to gain access for osteodistraction of the anterior maxilla to improve the vector of force during distraction. This case report illustrates a novel approach to anterior maxillary osteodistraction. The palatal approach allows the maxillary segment to be moved anteriorly and inferiorly. This is in contrast to the buccal approach, in which the palatal tissue creates a vector of force toward the palate. The vascular pedicle for the transport segment is the labial mucosa and musculature. In the present case, the alveolar segment was advanced 3.6 mm anteriorly and 12.2 mm inferiorly as measured by pre- and postoperative computed tomograms. This patient with a large vertical alveolar defect and high smile line had successful restoration with dental implants. The result has been stable for 14 months. In this case, the palatal approach to the anterior maxillary osteotomy was shown to be an effective method of reconstructing a large vertical anterior defect. Copyright © 2015 American Association of Oral and Maxillofacial Surgeons. Published by Elsevier Inc. All rights reserved.

History, heresy and radiology in scientific discovery.

PubMed

McCredie, J

2009-10-01

Nowadays, most drugs reach the market after research has established their pharmacology, safety and efficacy. That was not always the case 50 years ago. Thalidomide was used before its target cell or mode of action were known. Commencing with the thalidomide catastrophe--an epidemic of gross birth defects (1958-1962)--thalidomide's origins are revisited to show how this drug came to be made and sold in the 1950s. Thalidomide intersected with Australian radiology in the 1970s. The site and mode of action of the drug was deduced from X-rays of thalidomide-induced bone defects, which have classical radiological signs of sensory neuropathic osteoarthropathy. The longitudinal reduction deformities follow the distribution of segmental sensory innervation of the limb skeleton, indicating neural crest as the target organ. Injury to one level of neural crest halts normal neurotrophism and deletes the dependent segment--a previously unrecognised embryonic mechanism that explains most non-genetic birth defects. The final common pathway is neural crest injury and failure of normal neurotrophism to result in longitudinal reduction deformities, for example, phocomelia.

Functional end-arterial circulation of the choroid assessed by using fat embolism and electric circuit simulation.

PubMed

Lee, Ji Eun; Ahn, Ki Su; Park, Keun Heung; Pak, Kang Yeun; Kim, Hak Jin; Byon, Ik Soo; Park, Sung Who

2017-05-30

The discrepancy in the choroidal circulation between anatomy and function has remained unsolved for several decades. Postmortem cast studies revealed extensive anastomotic channels, but angiographic studies indicated end-arterial circulation. We carried out experimental fat embolism in cats and electric circuit simulation. Perfusion defects were observed in two categories. In the scatter perfusion defects suggesting an embolism at the terminal arterioles, fluorescein dye filled the non-perfused lobule slowly from the adjacent perfused lobule. In the segmental perfusion defects suggesting occlusion of the posterior ciliary arteries, the hypofluorescent segment became perfused by spontaneous resolution of the embolism without subsequent smaller infarction. The angiographic findings could be simulated with an electric circuit. Although electric currents flowed to the disconnected lobule, the level was very low compared with that of the connected ones. The choroid appeared to be composed of multiple sectors with no anastomosis to other sectors, but to have its own anastomotic arterioles in each sector. Blood flows through the continuous choriocapillaris bed in an end-arterial nature functionally to follow a pressure gradient due to the drainage through the collector venule.

Chevron Defect at the Intersection of Grain Boundaries with Free Surfaces in Au

NASA Astrophysics Data System (ADS)

Radetic, T.; Lançon, F.; Dahmen, U.

2002-08-01

We have identified a new defect at the intersection between grain boundaries and surfaces in Au using atomic resolution transmission electron microscopy. At the junction line of 90° <110> tilt grain boundaries of (110)-(001) orientation with the free surface, a small segment of the grain boundary, about 1nm in length, dissociates into a triangular region with a chevronlike stacking disorder and a distorted hcp structure. The structure and stability of these defects are confirmed by atomistic simulations, and we point out the relationship with the one-dimensional incommensurate structure of the grain boundary.

Evaluation of changes in perfusion defect and left ventricular systolic function using Tc-99m Tetrofosmin single photon emission computed tomography over 3 month period in patients of Acute Myocardial Infarction undergoing primary angioplasty.

PubMed

Kumar, Avs Anil; Kumar, P G; Swami, Ajay; Dinker, Yateendra

2018-01-01

After a primary transluminal coronary angioplasty (PTCA) following AMI (acute myocardial infarction), the perfusion defect and LV (left ventricular) function recover/change over a period of time. The analysis immediately after the procedure may not be true depiction of the exact success of the procedure. There is varying and scanty information available on the natural course of changes in these parameters after a successful PTCA. We hypothesized that majority of change occurs at 3-4 month period. Hence, we undertook this study on the natural course of recovery/changes occurring in perfusion defect size and LV function in first 3 months after primary angioplasty MATERIAL AND METHODS: 30 consecutive cases of first AMI who were taken up for Primary angioplasty were enrolled into the study. Resting MPI(Myocardial perfusion imaging) was done within 24-72 hrs of admission using Tc-99m-Tetrofosmin and after 10-14 weeks. Analysis of LVEF (left ventricular ejection fraction), summed segmental score and extent of perfusion defect was done. Images were processed using autocardiac software of emory tool box and quantification was done using QPS (quantitative perfusion SPECT) and QGS (qualitative perfusion SPECT) softwares. 20 segment scoring method was used for quantification on bull's eye images. Student t test (two tailed, dependent) was used to find the significance of study parameters on continuous scale within each group. Effect size was computed to find the effect. Pearson correlation between perfusion defect and LVEF was performed at acute stage and after 10-14 weeks. The average acute perfusion defect extent was 19.76 ± 12.89% which after 3months became 16.79 ± 12.61%. The summed segmental score changed from 14.31 ± 10.58 to 11.38 ± 10.03 and LVEF improved from 48.40 ± 13.15% to 53.37 ± 12.8%. There was significant improvement in LVEF from acute setting to 10-14 weeks (p = 0.001). There was significant lowering of summed score (p = 0.007). Perfusion defect size showed significant reduction (p = 0.030). Three patients showed deterioration in perfusion defect size and in summed score with reduction in LVEF. Four patients had no change in any of the parameters. Correlation between perfusion defect and LVEF was strong both at baseline (r = -0.705, p < 0.001) and after 10-18 weeks (r = -0.766, p < 0.001). The changes we found in 3 months are similar to earlier studies and also to studies using follow up at 6 months to 1 year. We feel that 3 months is a good enough time to accurately assess the success of primary angioplasty.

Reversibility by dipyridamole of thallium-201 myocardial scan defects in patients with sarcoidosis

DOE Office of Scientific and Technical Information (OSTI.GOV)

Tellier, P.; Paycha, F.; Antony, I.

1988-08-01

In order to clarify the significance of anginal pain and myocardial thallium-201 scan defects in cardiac sarcoidosis, the pharmacologic effect of dipyridamole on myocardial perfusion was assessed by planar thallium-201 myocardial scintigraphy in patients with sarcoidosis. Thallium-201 myocardial scintigraphy was performed at rest and after 0.56 mg/kg intravenous dipyridamole during four minutes in 16 patients with sarcoidosis. The myocardial scan (45-degree and 70-degree left anterior oblique, and anterior views) was divided into 15 segments. Results were evaluated by the number of segmental defects and with a global perfusion score (from 0 to 60) by a semi-quantitative index depending on themore » size and severity of myocardial thallium-201 defects. Thirteen of the 16 patients showed partial or total reversion of their thallium-201 defects on redistribution scanning either at rest or after dipyridamole. The mean (+/- SD) number of myocardial perfusion defects that were present in all the patients decreased from 5.31 +/- 1.78 at rest to 3.25 +/- 2.52 after redistribution (p less than 0.001) and to 2.19 +/- 2.10 after dipyridamole (p less than 0.001). The mean global perfusion score increased from 53.2 +/- 3.0 at rest to 56.2 +/- 2.9 after redistribution (p less than 0.001) and to 57.2 +/- 2.7 after dipyridamole (p less than 0.001). A significant correlation (r = 0.82, p less than 0.001) was found between the increase of global perfusion score on redistribution and after dipyridamole. The reversibility of myocardial scan defects is a common finding in sarcoidosis. It makes unlikely the role of scar fibrosis or extensive confluent granulomas as a mechanism for such defects. The effect of dipyridamole suggests the presence of reversible disorders lying at the coronary microvascular level.« less

Spillover Compensation in the Presence of Respiratory Motion Embedded in SPECT Perfusion Data

NASA Astrophysics Data System (ADS)

Pretorius, P. Hendrik; King, Michael A.

2008-02-01

Spillover from adjacent significant accumulations of extra-cardiac activity decreases diagnostic accuracy of SPECT perfusion imaging in especially the inferior/septal cardiac region. One method of compensating for the spillover at some location outside of a structure is to estimate it as the counts blurred into this location when a template (3D model) of the structure undergoes simulated imaging followed by reconstruction. The objective of this study was to determine what impact uncorrected respiratory motion has on such spillover compensation of extra-cardiac activity in the right coronary artery (RCA) territory, and if it is possible to use manual segmentation to define the extra-cardiac activity template(s) used in spillover correction. Two separate MCAT phantoms (1283 matrices) were simulated to represent the source and attenuation distributions of patients with and without respiratory motion. For each phantom the heart was modeled: 1) with a normal perfusion pattern and 2) with an RCA defect equal to 50% of the normal myocardium count level. After Monte Carlo simulation of 64times64times120 projections with appropriate noise, data were reconstructed using the rescaled block iterative (RBI) algorithm with 30 subsets and 5 iterations with compensation for attenuation, scatter and resolution. A 3D Gaussian post-filter with a sigma of 0.476 cm was used to suppress noise. Manual segmentation of the liver in filtered emission slices was used to create 3D binary templates. The true liver distribution (with and without respiratory motion included) was also used as binary templates. These templates were projected using a ray-driven projector simulating the imaging system with the exclusion of Compton scatter and reconstructed using the same protocol as for the emission data, excluding scatter compensation. Reconstructed templates were scaled using reconstructed emission count levels from the liver, and spillover subtracted outside the template. It was evident from the polar maps that the manually segmented template reconstructions were unable to remove all the spillover originating in the liver from the inferior wall. This was especially noticeable when a perfusion defect is present. Templates based on the true liver distribution appreciably improved spillover correction. Thus the emerging combined SPECT/CT technology may play a vital role in identifying and segmenting extra-cardiac structures more reliably thereby facilitating spillover correction. This study also indicates that compensation for respiratory motion might play an important role in spillover compensation.

In vitro cytotoxicity and in vivo osseointergration properties of compression-molded HDPE-HA-Al2O3 hybrid biocomposites.

PubMed

Tripathi, Garima; Gough, Julie E; Dinda, Amit; Basu, Bikramjit

2013-06-01

The aim of this study was to investigate the in vivo biocompatibility in terms of healing of long segmental bone defect in rabbit model as well as in vitro cytotoxicity of eluates of compression-molded High density polyethylene (HDPE)-hydroxyapatite (HA)-aluminum oxide (Al2O3) composite-based implant material. Based on the physical property in terms of modulus and strength properties, as reported in our recent publication, HDPE-40 wt % HA and HDPE-20 wt % HA-20 wt % Al2O3 hybrid composites were used for biocompatibility assessment. Osteoblasts cells were cultured in conditioned media, which contains varying amount of composite eluate (0.01, 0.1, and 1.0 wt %). In vitro, the eluates did not exhibit any significant negative impact on proliferation, mineralization or on morphology of human osteoblast cells. In vivo, the histological assessment revealed neobone formation at the bone/implant interface, characterized by the presence of osteoid and osteoblasts. The observation of osteoclastic activity indicates the process of bone remodeling. No inflammation to any noticeable extent was observed at the implantation site. Overall, the combination of in vitro and in vivo results are suggestive of potential biomedical application of compression-molded HDPE- 20 wt % HA- 20 wt % Al2O3 composites to heal long segmental bone defects without causing any toxicity of bone cells. Copyright © 2012 Wiley Periodicals, Inc.

Nano-biphasic calcium phosphate/polyvinyl alcohol composites with enhanced bioactivity for bone repair via low-temperature three-dimensional printing and loading with platelet-rich fibrin

PubMed Central

Wang, Chunmei; Zhang, Shuaishuai; Li, Donglin; Wang, Jimeng; Cao, Tianqing; Bi, Long; Pei, Guoxian

2018-01-01

Background and aim As a newly emerging three-dimensional (3D) printing technology, low-temperature robocasting can be used to fabricate geometrically complex ceramic scaffolds at low temperatures. Here, we aimed to fabricate 3D printed ceramic scaffolds composed of nano-biphasic calcium phosphate (BCP), polyvinyl alcohol (PVA), and platelet-rich fibrin (PRF) at a low temperature without the addition of toxic chemicals. Methods Corresponding nonprinted scaffolds were prepared using a freeze-drying method. Compared with the nonprinted scaffolds, the printed scaffolds had specific shapes and well-connected internal structures. Results The incorporation of PRF enabled both the sustained release of bioactive factors from the scaffolds and improved biocompatibility and biological activity toward bone marrow-derived mesenchymal stem cells (BMSCs) in vitro. Additionally, the printed BCP/PVA/PRF scaffolds promoted significantly better BMSC adhesion, proliferation, and osteogenic differentiation in vitro than the printed BCP/PVA scaffolds. In vivo, the printed BCP/PVA/PRF scaffolds induced a greater extent of appropriate bone formation than the printed BCP/PVA scaffolds and nonprinted scaffolds in a critical-size segmental bone defect model in rabbits. Conclusion These experiments indicate that low-temperature robocasting could potentially be used to fabricate 3D printed BCP/PVA/PRF scaffolds with desired shapes and internal structures and incorporated bioactive factors to enhance the repair of segmental bone defects. PMID:29416332

Nano-biphasic calcium phosphate/polyvinyl alcohol composites with enhanced bioactivity for bone repair via low-temperature three-dimensional printing and loading with platelet-rich fibrin.

PubMed

Song, Yue; Lin, Kaifeng; He, Shu; Wang, Chunmei; Zhang, Shuaishuai; Li, Donglin; Wang, Jimeng; Cao, Tianqing; Bi, Long; Pei, Guoxian

2018-01-01

As a newly emerging three-dimensional (3D) printing technology, low-temperature robocasting can be used to fabricate geometrically complex ceramic scaffolds at low temperatures. Here, we aimed to fabricate 3D printed ceramic scaffolds composed of nano-biphasic calcium phosphate (BCP), polyvinyl alcohol (PVA), and platelet-rich fibrin (PRF) at a low temperature without the addition of toxic chemicals. Corresponding nonprinted scaffolds were prepared using a freeze-drying method. Compared with the nonprinted scaffolds, the printed scaffolds had specific shapes and well-connected internal structures. The incorporation of PRF enabled both the sustained release of bioactive factors from the scaffolds and improved biocompatibility and biological activity toward bone marrow-derived mesenchymal stem cells (BMSCs) in vitro. Additionally, the printed BCP/PVA/PRF scaffolds promoted significantly better BMSC adhesion, proliferation, and osteogenic differentiation in vitro than the printed BCP/PVA scaffolds. In vivo, the printed BCP/PVA/PRF scaffolds induced a greater extent of appropriate bone formation than the printed BCP/PVA scaffolds and nonprinted scaffolds in a critical-size segmental bone defect model in rabbits. These experiments indicate that low-temperature robocasting could potentially be used to fabricate 3D printed BCP/PVA/PRF scaffolds with desired shapes and internal structures and incorporated bioactive factors to enhance the repair of segmental bone defects.

Noonan syndrome: crossed fused ectopic kidneys and focal segmental glomerulosclerosis-a rare association.

PubMed

Gupta, Ankur; Khaira, Ambar; Lal, Charanjit; Mahajan, Sandeep; Tiwari, Suresh C

2009-10-01

Noonan syndrome is characterised by short stature, typical facial dysmorphology and congenital heart defects. Urogenital abnormalities are reported in 10% of the cases. We present a 14-year-old girl with characteristic features of Noonan syndrome and nephrotic-range proteinuria. She had crossed fused ectopic kidneys. Renal biopsy showed focal segmental glomerulosclerosis. Oral steroids were instituted and she responded well. The case highlights this novel renal presentation of Noonan syndrome.

Late-onset cone photoreceptor degeneration induced by R172W mutation in Rds and partial rescue by gene supplementation.

PubMed

Conley, Shannon; Nour, May; Fliesler, Steven J; Naash, Muna I

2007-12-01

R172W is a common mutation in the human retinal degeneration slow (RDS) gene, associated with a late-onset dominant macular dystrophy. In this study, the authors characterized a mouse model that closely mimics the human phenotype and tested the feasibility of gene supplementation as a disease treatment strategy. Transgenic mouse lines carrying the R172W mutation were generated. The retinal phenotype associated with this mutation in a low-expresser line (L-R172W) was examined, both structurally (histology with correlative immunohistochemistry) and functionally (electroretinography). By examining animals over time and with various rds genetic backgrounds, the authors evaluated the dominance of the defect. To assess the efficacy of gene transfer therapy as a treatment for this defect, a previously characterized transgenic line expressing the normal mouse peripherin/Rds (NMP) was crossed with a higher-expresser Rds line harboring the R172W mutation (H-R172W). Functional, structural, and biochemical analyses were used to assess rescue of the retinal disease phenotype. In the wild-type (WT) background, L-R172W mice exhibited late-onset (12-month) dominant cone degeneration without any apparent effect on rods. The degeneration was slightly accelerated (9 months) in the rds(+/-) background. L-R172W retinas did not form outer segments in the absence of endogenous Rds. With use of the H-R172W line on an rds(+/-) background for proof-of-principle genetic supplementation studies, the NMP transgene product rescued rod and cone functional defects and supported outer segment integrity up to 3 months of age, but the rescue effect did not persist in older (11-month) animals. The R172W mutation leads to dominant cone degeneration in the mouse model, regardless of the expression level of the transgene. In contrast, effects of the mutation on rods are dose dependent, underscoring the usefulness of the L-R172W line as a faithful model of the human phenotype. This model may prove helpful in future studies on the mechanisms of cone degeneration and for elucidating the different roles of Rds in rods and cones. This study provides evidence that Rds genetic supplementation can be used to partially rescue visual function. Although this strategy is capable of rescuing haploinsufficiency, it does not rescue the long-term degeneration associated with a gain-of-function mutation.

Mandibular kinematics and maximum voluntary bite force following segmental resection of the mandible without or with reconstruction.

PubMed

Linsen, Sabine S; Oikonomou, Annina; Martini, Markus; Teschke, Marcus

2018-05-01

The purpose was to analyze mandibular kinematics and maximum voluntary bite force in patients following segmental resection of the mandible without and with reconstruction (autologous bone, alloplastic total temporomandibular joint replacement (TMJ TJR)). Subjects operated from April 2002 to August 2014 were enrolled in the study. Condylar (CRoM) and incisal (InRoM) range of motion and deflection during opening, condylar retrusion, incisal lateral excursion, mandibular rotation angle during opening, and maximum voluntary bite force were determined on the non-affected site and compared between groups. Influence of co-factors (defect size, soft tissue deficit, neck dissection, radiotherapy, occlusal contact zones (OCZ), and time) was determined. Twelve non-reconstructed and 26 reconstructed patients (13 autologous, 13 TMJ TJR) were included in the study. InRoM opening and bite force were significantly higher (P ≤ .024), and both condylar and incisal deflection during opening significantly lower (P ≤ .027) in reconstructed patients compared with non-reconstructed. Differences between the autologous and the TMJ TJR group were statistically not significant. Co-factors defect size, soft tissue deficit, and neck dissection had the greatest impact on kinematics and number of OCZs on bite force. Reconstructed patients (both autologous and TMJ TJR) have better overall function than non-reconstructed patients. Reconstruction of segmental mandibular resection has positive effects on mandibular function. TMJ TJR seems to be a suitable technique for the reconstruction of mandibular defects including the TMJ complex.

Reconstruction of Traumatic Bone Defect With In Situ Implantation of Dropped Traumatic Segmental Bone Fragments.

PubMed

Lin, Dasheng; Luo, Deqing; Lian, Kejian; Zhai, Wenliang; Ding, Zhenqi

2016-01-01

This study was conducted to determine whether in situ implantation of a dropped traumatic segmental bone fragment is safe and whether the authors' method would reduce the incidence of infectious and related complications. The authors retrospectively reviewed 16 patients with open fractures, including 11 with Gustilo-Anderson type IIIA fractures and 5 with Gustilo-Anderson type IIIB fractures who had a dropped traumatic segmental bone fragment between January 2002 and January 2012. Mean patient age was 35.4 years (range, 19-47 years). There were 10 femurs and 6 tibias. Average postoperative follow-up was 26.8 months (range, 12-60 months). The dropped traumatic segmental bone fragments were cleaned with 3% hydrogen peroxide, placed in separate sterile cups, and soaked in 1% iodophor for 30 minutes. Initial treatment included surgical debridement, wound irrigation, in situ implantation of the dropped traumatic segmental bone fragment, and temporary external fixation. Approximately 4 to 8 weeks later, after successful reconstruction of the soft tissue envelope, minimally invasive plate osteosynthesis was performed. Mean duration of treatment was 8 weeks (range, 6-14 weeks). All patients had fracture union at final follow-up. Mean healing time was 21.8 weeks (range, 14-48 weeks). One patient did not achieve primary union and required bone grafting. One patient with a Gustilo-Anderson type IIIB fracture had deep infection and removal of the dropped traumatic segmental bone fragment and bone grafting. According to the Klemm and Börner classification, 11 patients had excellent results, 3 had good results, and 2 had poor results. With adequate soft tissue coverage, this method was acceptable for the management of open fractures with bone defects. Copyright 2016, SLACK Incorporated.

Detection of small surface defects using DCT based enhancement approach in machine vision systems

NASA Astrophysics Data System (ADS)

He, Fuqiang; Wang, Wen; Chen, Zichen

2005-12-01

Utilizing DCT based enhancement approach, an improved small defect detection algorithm for real-time leather surface inspection was developed. A two-stage decomposition procedure was proposed to extract an odd-odd frequency matrix after a digital image has been transformed to DCT domain. Then, the reverse cumulative sum algorithm was proposed to detect the transition points of the gentle curves plotted from the odd-odd frequency matrix. The best radius of the cutting sector was computed in terms of the transition points and the high-pass filtering operation was implemented. The filtered image was then inversed and transformed back to the spatial domain. Finally, the restored image was segmented by an entropy method and some defect features are calculated. Experimental results show the proposed small defect detection method can reach the small defect detection rate by 94%.

Reconstruction of a Post Traumatic Anterior Maxillary Defect by Transport Distraction Osteogenesis.

PubMed

Rajkumar, K; Neelakandan, R S; Devadoss, Pradeep; Bandyopadhyay, T K

2017-03-01

Rehabilitation of segmental defects of maxilla presents a reconstructive challenge to obtain an ideal osseous form and height with adequate soft tissue investment. Though variety of prosthetic and surgical reconstructive options like the use of vascularized and non vascularized bone grafts are available they produce less than optimal results. Bone transport distraction is a reliable procedure in various maxillofacial bony defect reconstruction techniques. We describe herein a technique of maxillary bone transport distraction using an indigenously designed, custom made trifocal transport distractor performed in a post traumatic avulsive defect of the anterior maxilla. Transport distraction was successful for anterior maxillary alveolar bony regeneration, with excellent soft tissue cover and vestibular depth, which also helped close an oroantral/oronasal fistula.

Implications of segment mismatch for influenza A virus evolution

PubMed Central

White, Maria C.; Lowen, Anice C.

2018-01-01

Influenza A virus (IAV) is an RNA virus with a segmented genome. These viral properties allow for the rapid evolution of IAV under selective pressure, due to mutation occurring from error-prone replication and the exchange of gene segments within a co-infected cell, termed reassortment. Both mutation and reassortment give rise to genetic diversity, but constraints shape their impact on viral evolution: just as most mutations are deleterious, most reassortment events result in genetic incompatibilities. The phenomenon of segment mismatch encompasses both RNA- and protein-based incompatibilities between co-infecting viruses and results in the production of progeny viruses with fitness defects. Segment mismatch is an important determining factor of the outcomes of mixed IAV infections and has been addressed in multiple risk assessment studies undertaken to date. However, due to the complexity of genetic interactions among the eight viral gene segments, our understanding of segment mismatch and its underlying mechanisms remain incomplete. Here, we summarize current knowledge regarding segment mismatch and discuss the implications of this phenomenon for IAV reassortment and diversity. PMID:29244017

Bone regeneration with active angiogenesis by basic fibroblast growth factor gene transfected mesenchymal stem cells seeded on porous beta-TCP ceramic scaffolds.

PubMed

Guo, Xiaodong; Zheng, Qixin; Kulbatski, Iris; Yuan, Quan; Yang, Shuhua; Shao, Zengwu; Wang, Hong; Xiao, Baojun; Pan, Zhengqi; Tang, Shuo

2006-09-01

Large segmental bone defect repair remains a clinical and scientific challenge with increasing interest focused on combining gene transfer with tissue engineering techniques. Basic fibroblast growth factor (bFGF) is one of the most prominent osteogenic growth factors that has the potential to accelerate bone healing by promoting the proliferation and differentiation of mesenchymal stem cells (MSCs) and the regeneration of capillary vasculature. However, the short biological half-lives of growth factors may impose severe restraints on their clinical usefulness. Gene-based delivery systems provide a better way of achieving a sustained high concentration of growth factors locally in the defect and delivering a more biologically active product than that achieved by exogenous application of recombinant proteins. The objective of this experimental study was to investigate whether the bFGF gene modified MSCs could enhance the repair of large segmental bone defects. The pcDNA3-bFGF gene transfected MSCs were seeded on biodegradable porous beta tricalcium phosphate (beta-TCP) ceramics and allografted into the 15 mm critical-sized segmental bone defects in the radius of 18 New Zealand White rabbits. The pcDNA3 vector gene transfected MSCs were taken as the control. The follow-up times were 2, 4, 6, 8, 10 and 12 weeks. Scanning electron microscopic, roentgenographic, histologic and immunohistological studies were used to assess angiogenesis and bone regeneration. In vitro, the proliferation and differentiation of bFGF gene transfected MSCs were more active than that of the control groups. In vivo, significantly more new bone formation accompanied by abundant active capillary regeneration was observed in pores of the ceramics loaded with bFGF gene transfected MSCs, compared with control groups. Transfer of gene encoding bFGF to MSCs increases their osteogenic properties by enhancing capillary regeneration, thus providing a rich blood supply for new bone formation. This new bFGF gene enhanced tissue engineering strategy could be of potential benefit to accelerate bone healing, especially in defects caused by atrophic nonunion and avascular necrosis of the femoral head.

Reconstruction of large diaphyseal bone defect by simplified bone transport over nail technique: A 7-case series.

PubMed

Ferchaud, F; Rony, L; Ducellier, F; Cronier, P; Steiger, V; Hubert, L

2017-11-01

Reconstruction of large diaphyseal bone defect is complex and the complications rate is high. This study aimed to assess a simplified technique of segmental bone transport by monorail external fixator over an intramedullary nail.A prospective study included 7 patients: 2 femoral and 5 tibial defects. Mean age was 31years (range: 16-61years). Mean follow-up was 62 months (range: 46-84months). Defects were post-traumatic, with a mean length of 7.2cm (range: 4 to 9.5cm). For 3 patients, reconstruction followed primary failure. In 4 cases, a covering flap was necessary. Transport used an external fixator guided by an intramedullary nail, at a rate of 1mm per day. One pin was implanted on either side of the distraction zone. The external fixator was removed 1 month after bone contact at the docking site. Mean bone transport time was 11 weeks (range: 7-15 weeks). Mean external fixation time was 5.1months (range: 3.5 to 8months). Full weight-bearing was allowed 5.7months (range: 3.5-13months) after initiation of transport. In one patient, a pin had to be repositioned. In 3 patients, the transported segment re-ascended after external fixatorablation, requiring repeat external fixation and resumption of transport. There was just 1 case of superficial pin infection. Reconstruction quality was considered "excellent" on the Paley-Marr criteria in 6 cases. The present technique provided excellent reconstruction quality in 6 of the 7 cases. External fixation time was shorter and resumption of weight-bearing earlier than with other reconstruction techniques, notably including bone autograft, vascularized bone graft or the induced membrane technique. Nailing facilitated control of limb axis and length. The complications rate was 50%, comparable to other techniques. This study raises the question of systematic internal fixation of the docking site, to avoid any mobilization of the transported segment. The bone quality, axial control and rapidity shown by the present technique make it well-adapted to reconstruction of diaphyseal bone defect. Four-case series. Copyright © 2017 Elsevier Masson SAS. All rights reserved.

Ready-to-Use Tissue Construct for Military Bone and Cartilage Trauma

DTIC Science & Technology

2012-10-01

times. We hypothesize that our Ready-to-Use constructs can successfully restore 3 cm critical size segmental defects in dog tibiae. We will examine the...defects) of the grant. The approved IACUC protocol permits 3 pilot dogs for Aim 1 and 3 pilot dogs for Aim 2. Several minor modifications to the...original IACUC protocol were required which are provided in the Appendix. All the pilot dogs were to receive scaffolds composed of 90% poly-caprolactone

Pathology of Podocytopathies Causing Nephrotic Syndrome in Children.

PubMed

Ranganathan, Sarangarajan

2016-01-01

Nephrotic syndrome (NS) in children includes a diverse group of diseases that range from genetic diseases without any immunological defects to causes that are primarily due to immunological effects. Recent advances in molecular and genomic studies have resulted in a plethora of genetic defects that have been localized to the podocyte, the basic structure that is instrumental in normal filtration process. Although the disease can manifest from birth and into adulthood, the primary focus of this review would be to describe the novel genes and pathology of primary podocyte defects that cause NS in children. This review will restrict itself to the pathology of congenital NS, minimal change disease (MCD), and its variants and focal segmental glomerulosclerosis (FSGS). The two major types of congenital NS are Finnish type characterized by dilated sausage shaped tubules morphologically and diffuse mesangial sclerosis characterized by glomerulosclerosis. MCD has usually normal appearing biopsy features on light microscopy and needs electron microscopy for diagnosis, whereas FSGS in contrast has classic segmental sclerosing lesions identified in different portions of the glomeruli and tubular atrophy. This review summarizes the pathological characteristics of these conditions and also delves into the various genetic defects that have been described as the cause of these primary podocytopathies. Other secondary causes of NS in children, such as membranoproliferative and membranous glomerulonephritis, will not be covered in this review.

Axenfeld-Rieger syndrome.

PubMed

Seifi, M; Walter, M A

2018-06-01

Axenfeld-Rieger syndrome (ARS) is a clinically and genetically heterogeneous group of developmental disorders affecting primarily the anterior segment of the eye, often leading to secondary glaucoma. Patients with ARS may also present with systemic changes, including dental defects, mild craniofacial dysmorphism, and umbilical anomalies. ARS is inherited in an autosomal-dominant fashion; the underlying defect in 40% of patients is mutations in PITX2 or FOXC1. Here, an overview of the clinical spectrum of ARS is provided. As well, the known underlying genetic defects, clinical diagnostic possibilities, genetic counseling and treatments of ARS are discussed in detail. © 2017 John Wiley & Sons A/S. Published by John Wiley & Sons Ltd.

Video: two novel endoscopic esophageal lengthening and reconstruction techniques.

PubMed

Perretta, Silvana; Wall, James K; Dallemagne, Bernard; Harrison, Michael; Becmeur, François; Marescaux, Jacques

2011-10-01

Esophageal reconstruction presents a significant clinical challenge in patients ranging from neonates with long-gap esophageal atresia to adults after esophageal resection. Both gastric and colonic replacement conduits carry significant morbidity. As emerging organ-sparring techniques become established for early stage esophageal tumors, less morbid reconstruction techniques are warranted. We present two novel endoscopic approaches for esophageal lengthening and reconstruction in a porcine model. Two models of esophageal defects were created in pigs (30-35 kg) under general anesthesia and subsequently reconstructed with the novel techniques. The first model was a segmental defect of the esophagus created by thoracoscopically transecting the esophagus above the gastroesophageal (GE) junction. The first reconstruction technique involved bilateral submucosal endoscopic lengthening myotomies (BSELM) with a magnetic compression anastomosis (MAGNAMOSIS™). The second model was a wedge defect in the anterior esophagus created above the GE junction through a laparotomy. The second reconstruction technique involved an inverted mucosal-submucosal sleeve transposition graft (IMSTG) that crossed the esophageal gap and was secured in place with a self-expandable covered esophageal stent. Both techniques were feasible in the pig model. The BSELM approach lengthened the esophagus 1 cm for every 2 cm length of myotomy. The myotomy targeted only the inner circular fibers of the esophagus, with preservation of the longitudinal layer to protect against long-term dilation and pouching. The IMSTG approach generated a vascularized mucosal graft almost as long as the esophagus itself. Emerging endoscopic capabilities are enabling complex endoluminal esophageal procedures. BSELM and IMSTG are two novel and technically feasible approaches to esophageal lengthening and reconstruction. Further survival studies are needed to establish the safety and efficacy of these techniques.

High Concordance Between Mental Stress-Induced and Adenosine-Induced Myocardial Ischemia Assessed Using SPECT in Heart Failure Patients: Hemodynamic and Biomarker Correlates.

PubMed

Wawrzyniak, Andrew J; Dilsizian, Vasken; Krantz, David S; Harris, Kristie M; Smith, Mark F; Shankovich, Anthony; Whittaker, Kerry S; Rodriguez, Gabriel A; Gottdiener, John; Li, Shuying; Kop, Willem; Gottlieb, Stephen S

2015-10-01

Mental stress can trigger myocardial ischemia, but the prevalence of mental stress-induced ischemia in congestive heart failure (CHF) patients is unknown. We characterized mental stress-induced and adenosine-induced changes in myocardial perfusion and neurohormonal activation in CHF patients with reduced left-ventricular function using SPECT to precisely quantify segment-level myocardial perfusion. Thirty-four coronary artery disease patients (mean age±SD, 62±10 y) with CHF longer than 3 mo and ejection fraction less than 40% underwent both adenosine and mental stress myocardial perfusion SPECT on consecutive days. Mental stress consisted of anger recall (anger-provoking speech) followed by subtraction of serial sevens. The presence and extent of myocardial ischemia was quantified using the conventional 17-segment model. Sixty-eight percent of patients had 1 ischemic segment or more during mental stress and 81% during adenosine. On segment-by-segment analysis, perfusion with mental stress and adenosine were highly correlated. No significant differences were found between any 2 time points for B-type natriuretic peptide, tumor necrosis factor-α, IL-1b, troponin, vascular endothelin growth factor, IL-17a, matrix metallopeptidase-9, or C-reactive protein. However, endothelin-1 and IL-6 increased, and IL-10 decreased, between the stressor and 30 min after stress. Left-ventricular end diastolic dimension was 179±65 mL at rest and increased to 217±71 after mental stress and 229±86 after adenosine (P<0.01 for both). Resting end systolic volume was 129±60 mL at rest and increased to 158±66 after mental stress (P<0.05) and 171±87 after adenosine (P<0.07), with no significant differences between adenosine and mental stress. Ejection fraction was 30±12 at baseline, 29±11 with mental stress, and 28±10 with adenosine (P=not significant). There was high concordance between ischemic perfusion defects induced by adenosine and mental stress, suggesting that mental stress is equivalent to pharmacologic stress in eliciting clinically significant myocardial perfusion defects in CHF patients. Cardiac dilatation suggests clinically important changes with both conditions. Psychosocial stressors during daily life may contribute to the ischemic burden of CHF patients with coronary artery disease. © 2015 by the Society of Nuclear Medicine and Molecular Imaging, Inc.

Evaluation of rhBMP-2/collagen/TCP-HA bone graft with and without bone marrow cells in the canine femoral multi defect model.

PubMed

Luangphakdy, V; Shinohara, K; Pan, H; Boehm, C; Samaranska, A; Muschler, G F

2015-01-12

Recombinant human bone morphogenetic protein-2, when applied to an absorbable type 1 bovine collagen sponge (rhBMP-2/ACS) is an effective therapy in many bone grafting settings. Bone marrow aspirate (BMA) has also been used as a source of transplantable osteogenic connective tissue progenitors. This study was designed to characterize the performance of a scaffold comprising rhBMP-2/ACS in which the sponge wraps around tri-calcium phosphate hydroxyapatite granules (rhBMP-2/ACS/TCP-HA) and to test the hypothesis that addition of BMA will improve the performance of this construct in the Canine Femoral Multi Defect Model. In each subject, two sites were grafted with rhBMP-2/ACS/TCP-HA scaffold loaded with BMA clot and two other sites with rhBMP-2/ACS/TCP-HA scaffold loaded with wound blood (WB). After correction for unresorbed TCP-HA granules, sites grafted with rhBMP-2/ACS/TCP-HA+BMA and rhBMP-2/ACS/TCP-HA+WB were similar, with mean percent bone volumes of 10.9 %±1.2 and 11.2 %±1.2, respectively. No differences were seen in quantitative histomorphometry. While bone formation using both constructs was robust, this study did not support the hypothesis that the addition of unprocessed bone marrow aspirate clot improved bone regeneration in a site engrafted with rhBMP-2/ACS/TCP-HA+BMA. In contrast to prior studies using this model, new bone formation was greater at the center of the defect where TCP-HA was distributed. This finding suggests a potential synergy between rhBMP-2 and the centrally placed ceramic and cellular components of the graft construct. Further optimization may also require more uniform distribution of TCP-HA, alternative cell delivery strategies, and a more rigorous large animal segmental defect model.

[Gemstone computed tomography in the evaluation of material distribution in pulmonary parenchyma for pulmonary embolism].

PubMed

Zhang, Lan; Lü, Lei; Wu, Hua-wei; Zhang, Hao; Zhang, Ji-wei

2011-12-06

To present our initial experiences with pulmonary high-definition multidetector computed tomography (HDCT) in patients with acute venous thromboembolism (AVTE) to evaluate their corresponding clinical manifestations. Since December 2009 to March 2010, 23 AVTE patients underwent HDCT at our hospital. Pulmonary embolism (PE) was diagnosed based on the 3D-reconstructed images of computed tomography pulmonary angiography (CTPA). The post processed data were collected by spectral imaging system software to detect the iodine distribution maps. Perfusion defects, calculated as the values of iodine content, were compared with those of normal lung parenchymal perfusion in the absence of PE. Among them, 14 AVTE patients were definitely diagnosed with PE. Prior to anticoagulant therapy, their values of iodine content in defective perfusion area were significantly lower than those in normal perfusion area. After a 3-month anticoagulant therapy, the values of iodine content for the defective perfusion area increased significantly (P < 0.05). There was no significant correlation between the values of iodine content for segmental/subsegmental filling defect area and clinical risk score of DVT (r = 2.68, P > 0.05). But there was a significant negative correlation between the values of iodine content for segmental/subsegmental filling defection area and clinical probability score of PE (r = 0.78, P < 0.05). HDCT is a promising modality of visualizing pulmonary microvasculature as a correlative manifestation of regional perfusion. PE results in hypoperfusion with decreased values of iodine content in affected lung parenchyma. Hemodynamic changes in affected areas correlate with the severity of clinical manifestations of PE.

Vitreoretinal Interface Characteristics in Eyes with Idiopathic Macular Holes: Qualitative and Quantitative Analysis.

PubMed

Seyhan Karatepe, Arzu; Menteş, Jale; Erakgün, E Tansu; Afrashi, Filiz; Nalçacı, Serhad; Akkın, Cezmi; Ateş, Yeşim

2018-04-01

To determine the qualitative and quantitative vitreoretinal interface characteristics with spectral domain optical coherence tomography (SD-OCT) in eyes with macular hole (MH) and investigate their relation with best corrected visual acuity (BCVA) and MH duration. Sixty-one eyes of 46 consecutive patients diagnosed with idiopathic MH were included in the study. The mean age of the patients was 66.7±7.5 (51-79) years. Complete ophthalmologic examination and SD-OCT examination were performed in all eyes and MH stages were determined according to SD-OCT findings. Qualitative characteristics of the vitreoretinal interface were investigated, including vitreomacular traction, vitreopapillary traction, maculopapillary traction, vitreoschisis, intraretinal cyst, presence of epiretinal membrane, and the integrity of the photoreceptor inner segment-outer segment junction (IS/OS) and external limiting membrane (ELM). In addition, MH diameter, MH base diameter (MHBD), ELM defect diameter, IS/OS defect diameter, and MH height were quantitatively measured and the MH index was calculated. Out of 61 eyes, 9.8% were classified as stage 1a, 19.7% as stage 1b, 18% as stage 2, 23% as stage 3, and 29.5% as stage 4. Mean BCVA was 0.28±0.24 (1 mps-1.0) Snellen and MH duration was 10.08±18.6 (1-108) months. The most common interface characteristics associated with MH were determined as intraretinal cyst (91.8%), IS/OS defect (78.7%) and ELM defect (63.9%). Duration and stage of MH were inversely proportional to BCVA but directly proportional to the presence and diameter of IS/OS and ELM defects. BCVA was significantly lower in eyes with IS/OS and ELM defects (p<0.0001; p<0.0001 Mann-Whitney U test). We determined that the most important factors affecting BCVA in cases with idiopathic MH were MH stage, MH duration, MHBD, and the presence and diameter of IS/OS and ELM defects, which suggests that these parameters should be considered while making decisions about prognosis and treatment.

Adaptive neuro-heuristic hybrid model for fruit peel defects detection.

PubMed

Woźniak, Marcin; Połap, Dawid

2018-02-01

Fusion of machine learning methods benefits in decision support systems. A composition of approaches gives a possibility to use the most efficient features composed into one solution. In this article we would like to present an approach to the development of adaptive method based on fusion of proposed novel neural architecture and heuristic search into one co-working solution. We propose a developed neural network architecture that adapts to processed input co-working with heuristic method used to precisely detect areas of interest. Input images are first decomposed into segments. This is to make processing easier, since in smaller images (decomposed segments) developed Adaptive Artificial Neural Network (AANN) processes less information what makes numerical calculations more precise. For each segment a descriptor vector is composed to be presented to the proposed AANN architecture. Evaluation is run adaptively, where the developed AANN adapts to inputs and their features by composed architecture. After evaluation, selected segments are forwarded to heuristic search, which detects areas of interest. As a result the system returns the image with pixels located over peel damages. Presented experimental research results on the developed solution are discussed and compared with other commonly used methods to validate the efficacy and the impact of the proposed fusion in the system structure and training process on classification results. Copyright © 2017 Elsevier Ltd. All rights reserved.

Photovoltaic panel extraction from very high-resolution aerial imagery using region-line primitive association analysis and template matching

NASA Astrophysics Data System (ADS)

Wang, Min; Cui, Qi; Sun, Yujie; Wang, Qiao

2018-07-01

In object-based image analysis (OBIA), object classification performance is jointly determined by image segmentation, sample or rule setting, and classifiers. Typically, as a crucial step to obtain object primitives, image segmentation quality significantly influences subsequent feature extraction and analyses. By contrast, template matching extracts specific objects from images and prevents shape defects caused by image segmentation. However, creating or editing templates is tedious and sometimes results in incomplete or inaccurate templates. In this study, we combine OBIA and template matching techniques to address these problems and aim for accurate photovoltaic panel (PVP) extraction from very high-resolution (VHR) aerial imagery. The proposed method is based on the previously proposed region-line primitive association framework, in which complementary information between region (segment) and line (straight line) primitives is utilized to achieve a more powerful performance than routine OBIA. Several novel concepts, including the mutual fitting ratio and best-fitting template based on region-line primitive association analyses, are proposed. Automatic template generation and matching method for PVP extraction from VHR imagery are designed for concept and model validation. Results show that the proposed method can successfully extract PVPs without any user-specified matching template or training sample. High user independency and accuracy are the main characteristics of the proposed method in comparison with routine OBIA and template matching techniques.

Direct comparison of rest and adenosine stress myocardial perfusion CT with rest and stress SPECT

PubMed Central

Okada, David R.; Ghoshhajra, Brian B.; Blankstein, Ron; Rocha-Filho, Jose A.; Shturman, Leonid D.; Rogers, Ian S.; Bezerra, Hiram G.; Sarwar, Ammar; Gewirtz, Henry; Hoffmann, Udo; Mamuya, Wilfred S.; Brady, Thomas J.; Cury, Ricardo C.

2010-01-01

Introduction We have recently described a technique for assessing myocardial perfusion using adenosine-mediated stress imaging (CTP) with dual source computed tomography. SPECT myocardial perfusion imaging (SPECT-MPI) is a widely utilized and extensively validated method for assessing myocardial perfusion. The aim of this study was to determine the level of agreement between CTP and SPECT-MPI at rest and under stress on a per-segment, per-vessel, and per-patient basis. Methods Forty-seven consecutive patients underwent CTP and SPECT-MPI. Perfusion images were interpreted using the 17 segment AHA model and were scored on a 0 (normal) to 3 (abnormal) scale. Summed rest and stress scores were calculated for each vascular territory and patient by adding corresponding segmental scores. Results On a per-segment basis (n = 799), CTP and SPECT-MPI demonstrated excellent correlation: Goodman-Kruskall γ = .59 (P < .0001) for stress and .75 (P < .0001) for rest. On a per-vessel basis (n = 141), CTP and SPECT-MPI summed scores demonstrated good correlation: Pearson r = .56 (P < .0001) for stress and .66 (P < .0001) for rest. On a per-patient basis (n = 47), CTP and SPECT-MPI demonstrated good correlation: Pearson r = .60 (P < .0001) for stress and .76 (P < .0001) for rest. Conclusions CTP compares favorably with SPECT-MPI for detection, extent, and severity of myocardial perfusion defects at rest and stress. PMID:19936863

Anterior segment dysgenesis (Peters' anomaly) in two snow leopard (Panthera uncia) cubs.

PubMed

Hamoudi, Hassan; Rudnick, Jens-Christian; Prause, Jan U; Tauscher, Kerstin; Breithaupt, Angele; Teifke, Jens P; Heegaard, Steffen

2013-07-01

Two sibling snow leopards, a male and a female, with bilateral anterior segment dysgenesis (ASD), are reported. Both snow leopards also had colobomas of both upper eyelids. All eyes exhibited a central corneal opacity associated with a defect in posterior corneal stroma, endothelium and Descemet's membrane. Iris strands were present attached to the termination of Descemet's membrane and to the periphery of the posterior corneal defect. The iris was hypoplastic, and cataract was present in all four eyes. The left eye of the female was microphthalmic, with no trabecular meshwork and with persistent remnant of the hyaloid artery. The male had hydrocephalus and thus some of the features of Peters' plus syndrome (Peters' anomaly in addition to systemic malformations). The histological findings in the eyes of these snow leopard siblings are identical with those described in humans with Peters' anomaly. © 2012 American College of Veterinary Ophthalmologists.

CLASSIFICATION AND QUANTITATIVE ANALYSIS OF GEOGRAPHIC ATROPHY JUNCTIONAL ZONE USING SPECTRAL DOMAIN OPTICAL COHERENCE TOMOGRAPHY.

PubMed

Qu, Jinfeng; Velaga, Swetha Bindu; Hariri, Amir H; Nittala, Muneeswar Gupta; Sadda, Srinivas

2017-08-22

The junctional zone at the border of areas of geographic atrophy (GA) in eyes with nonneovascular age-related macular degeneration is an important target region for future therapeutic strategies. The goal of this study was to perform a detailed classification and quantitative characterization of the junctional zone using spectral domain optical coherence tomography. Spectral domain optical coherence tomography volume cube scans (Spectralis OCT, 1024 × 37, Automatic Real Time > 9) were obtained from 15 eyes of 11 patients with GA because of nonneovascular age-related macular degeneration. Volume optical coherence tomography data were imported into previously described validated grading software (3D-OCTOR), and manual segmentation of the retinal pigment epithelium (RPE) and photoreceptor layers was performed on all B-scans (total of 555). Retinal pigment epithelium and photoreceptor defect maps were produced for each case. The borders of the photoreceptor defect area and RPE defect area were delineated individually on separate annotation layers. The two outlines were then superimposed to compare the areas of overlap and nonoverlap. The perimeter of the RPE defect area was calculated by the software in pixels. The superimposed outline of the photoreceptor defect area and the RPE defect area was scrutinized to classify the overlap configuration of the junctional zone into one of three categories: Type 0, exact correspondence between the edge of the RPE defect and photoreceptor defect; Type 1, loss of photoreceptors outside and beyond the edge of the RPE defect; Type 2, preservation of photoreceptors beyond the edge of the RPE defect. The relative proportion of the various border configurations was expressed as a percentage of the perimeter of the RPE defect. Each configuration was then classified into four subgroups according to irregularity of the RPE band and the presence of debris. Fifteen eyes of 11 patients (mean age: 79.3 ± 4.3 years; range: 79-94 years) were included in this study. Seventeen GA lesions were analyzed. Two hundred and thirty-two B-scans were found to pass through the GA lesions, yielding 612 individual GA borders which were separately analyzed and classified. The mean area of the RPE defect was 4.0 ± 4.4 mm, which was significantly smaller than that of the photoreceptor defect which measured 4.4 ± 4.1 mm (paired t test, P = 0.037). On average, 18.0 ± 9.6% (range, 2.3-36.6%) of the junctional zone was of the Type 0 configuration, 57.3 ± 19.0% (range, 21.3-96.8%) was Type 1, and 24.7 ± 18.0% (range, 0.9-64.4%) was Type 2. Type 1 was more prevalent than Type 0 and 2 (analysis of variance, P = 0.000). Debris was present at the margin of the defect in 24.3% (149 of 612) of all assessed junctional zones; 20.0% (14 of 70) of Type 0 junctions, 28.7% (120 of 418) of Type 1, and 12.1% (15 of 124) of Type 2. Debris was more common in Type 1 than Type 2 junctions (P < 0.001). Retinal pigment epithelial irregularity was present at the margin of the defect in 34.8% (213 of 612) of all assessed junctional zones; 52.9% (37 of 70) of Type 0 junctions, 38.0% (159 of 418) of Type 1, and 13.7% (17 of 124) of Type 2. Retinal pigment epithelial irregularity was present more often at Type 0 and Type 1 than at Type 2 junctions (P < 0.001 for both). The size of the optical coherence tomography-visible RPE and photoreceptor defect in GA lesions differ significantly. There were significant areas where the photoreceptor outer segments were preserved despite the absence of visible RPE cells, and also areas of photoreceptor outer segment loss despite apparent RPE preservation. These findings have implications for development of therapeutic strategies, particularly cell-replacement approaches.

Deletion of Ku80 causes early aging independent of chronic inflammation and Rag-1-induced DSBs.

PubMed

Holcomb, Valerie B; Vogel, Hannes; Hasty, Paul

2007-01-01

Animal models of premature aging are often defective for DNA repair. Ku80-mutant mice are disabled for nonhomologous end joining; a pathway that repairs both spontaneous DNA double-strand breaks (DSBs) and induced DNA DSBs generated by the action of a complex composed of Rag-1 and Rag-2 (Rag). Rag is essential for inducing DSBs important for assembling V(D)J segments of antigen receptor genes that are required for lymphocyte development. Thus, deletion of either Rag-1 or Ku80 causes severe combined immunodeficiency (scid) leading to chronic inflammation. In addition, Rag-1 induces breaks at non-B DNA structures. Previously we reported Ku80-mutant mice undergo premature aging, yet we do not know the root cause of this phenotype. Early aging may be caused by either defective repair of spontaneous DNA damage, defective repair of Rag-1-induced breaks or chronic inflammation caused by scid. To address this issue, we analyzed aging in control and Ku80-mutant mice deleted for Rag-1 such that both cohorts are scid and suffer from chronic inflammation. We make two observations: (1) chronic inflammation does not cause premature aging in these mice and (2) Ku80-mutant mice exhibit early aging independent of Rag-1. Therefore, this study supports defective repair of spontaneous DNA damage as the root cause of early aging in Ku80-mutant mice.

A case of junctional neural tube defect associated with a lipoma of the filum terminale: a new subtype of junctional neural tube defect?

PubMed

Florea, Simona Mihaela; Faure, Alice; Brunel, Hervé; Girard, Nadine; Scavarda, Didier

2018-06-01

The embryological development of the central nervous system takes place during the neurulation process, which includes primary and secondary neurulation. A new form of dysraphism, named junctional neural tube defect (JNTD), was recently reported, with only 4 cases described in the literature. The authors report a fifth case of JNTD. This 5-year-old boy, who had been operated on during his 1st month of life for a uretero-rectal fistula, was referred for evaluation of possible spinal dysraphism. He had urinary incontinence, clubfeet, and a history of delayed walking ability. MRI showed a spinal cord divided in two, with an upper segment ending at the T-11 level and a lower segment at the L5-S1 level, with a thickened filum terminale. The JNTDs represent a recently classified dysraphism caused by an error during junctional neurulation. The authors suggest that their patient should be included in this category as the fifth case reported in the literature and note that this would be the first reported case of JNTD in association with a lipomatous filum terminale.

Reconstruction of Canine Mandibular Bone Defects Using a Bone Transport Reconstruction Plate

PubMed Central

Elsalanty, Mohammed E.; Zakhary, Ibrahim; Akeel, Sara; Benson, Byron; Mulone, Timothy; Triplett, Gilbert R.; Opperman, Lynne A.

2010-01-01

Objectives Reconstruction of mandibular segmental bone defects is a challenging task. This study tests a new device used for reconstructing mandibular defects based on the principle of bone transport distraction osteogenesis. Methods Thirteen beagle dogs were divided into control and experimental groups. In all animals, a 3 cm defect was created on one side of the mandible. In eight control animals, the defect was stabilized with a reconstruction plate without further reconstruction and the animals were sacrificed two to three months after surgery. The remaining five animals were reconstructed with a bone transport reconstruction plate (BTRP), comprising a reconstruction plate with attached intraoral transport unit, and were sacrificed after one month of consolidation. Results Clinical evaluation, cone-beam CT densitometry, three-dimensional histomorphometry, and docking site histology revealed significant new bone formation within the defect in the distracted group. Conclusion The physical dimensions and architectural parameters of the new bone were comparable to the contralateral normal bone. Bone union at the docking site remains a problem. PMID:19770704

Genetic Evidence for an Interferon-Antagonistic Function of Rift Valley Fever Virus Nonstructural Protein NSs

PubMed Central

Bouloy, Michèle; Janzen, Christian; Vialat, Pierre; Khun, Huot; Pavlovic, Jovan; Huerre, Michel; Haller, Otto

2001-01-01

Rift Valley fever virus (RVFV), a phlebovirus of the family Bunyaviridae, is a major public health threat in Egypt and sub-Saharan Africa. The viral and host cellular factors that contribute to RVFV virulence and pathogenicity are still poorly understood. All pathogenic RVFV strains direct the synthesis of a nonstructural phosphoprotein (NSs) that is encoded by the smallest (S) segment of the tripartite genome and has an undefined accessory function. In this report, we show that MP12 and clone 13, two attenuated RVFV strains with mutations in the NSs gene, were highly virulent in IFNAR−/− mice lacking the alpha/beta interferon (IFN-α/β) receptor but remained attenuated in IFN-γ receptor-deficient mice. Both attenuated strains proved to be excellent inducers of early IFN-α/β production. In contrast, the virulent strain ZH548 failed to induce detectable amounts of IFN-α/β and replicated extensively in both IFN-competent and IFN-deficient mice. Clone 13 has a defective NSs gene with a large in-frame deletion. This defect in the NSs gene results in expression of a truncated protein which is rapidly degraded. To investigate whether the presence of the wild-type NSs gene correlated with inhibition of IFN-α/β production, we infected susceptible IFNAR−/− mice with S gene reassortant viruses. When the S segment of ZH548 was replaced by that of clone 13, the resulting reassortants became strong IFN inducers. When the defective S segment of clone 13 was exchanged with the wild-type S segment of ZH548, the reassortant virus lost the capacity to stimulate IFN-α/β production. These results demonstrate that the ability of RVFV to inhibit IFN-α/β production correlates with viral virulence and suggest that the accessory protein NSs is an IFN antagonist. PMID:11152510

Early detection of radiation-induced heart disease using (99m)Tc-MIBI SPECT gated myocardial perfusion imaging in patients with oesophageal cancer during radiotherapy.

PubMed

Zhang, Peng; Hu, Xudong; Yue, Jinbo; Meng, Xue; Han, Dali; Sun, Xindong; Yang, Guoren; Wang, Shijiang; Wang, Xiaohui; Yu, Jinming

2015-05-01

The primary aim of this prospective study was to investigate the value of (99m)Tc-methoxyisobutylisonitrile (MIBI) single photon emission computed tomography (SPECT) gated myocardial perfusion imaging (GMPI) in the detection of radiation-induced heart disease (RIHD) as early as during radiotherapy (RT) for oesophageal cancer (EC). The second aim was to analyse the correlation between cardiac toxicity and the dose-volume factors. The (99m)Tc-MIBI SPECT GMPI was performed both pre-RT and during RT (40Gray). The results of the SPECT were quantitatively analysed with QGS/QPS software and read by two experienced nuclear medicine physicians. The correlation between the changes in the SPECT parameters and the RT dosimetric data was analysed. Eighteen patients with locally advanced EC were enrolled in the study. Compared with the baseline, the imaging during RT showed not only significant decreases in the wall motion (WM) (1/20 segments), wall thickening (WT) (2/20 segments), end-diastolic perfusion (EDP) (5/20 segments) and end-systolic perfusion (ESP) (8/20 segments) (p<0.05) but also a significant increase in the heart rate (74.63±7.79 vs 81.49±9.90, p=0.036). New myocardial perfusion defects were observed in 8 of the 18 patients. The V37-V40 was significantly higher (p<0.05) in the patients with the new perfusion defects during RT than in the patients who did not exhibit these defects. Radiotherapy for EC induces cardiac damage from an early stage. (99m)Tc-MIBI SPECT GMPI can detect the occurrence of cardiac impairment during RT. The WM, WT, EDP and ESP may be valuable as early indicators of RIHD. The percentage of the heart volume that receives a high dose is an important factor that is correlated with RIHD. Copyright © 2015 Elsevier Ireland Ltd. All rights reserved.

Enhanced Bone Formation in Segmental Defects with BMP2 in a Biologically Relevant Molecular Context

DTIC Science & Technology

2016-10-16

gun shots . These do not heal on their own once a ‘critical size’ segment of bone is missing. One strategy to induce healing is to use bone-inducing...accelerate BMP2-induced bone formation by presenting the growth factor in a more biologically relevant context. This is based on our observation...that manganese increases the binding of BMP2 to COMP. The next steps are to validate these observations using BMP2:COMP on HA/PLG scaffolds in-vitro

Enhanced Healing of Segmental Bone Defects by Modulation of the Mechanical Environment

DTIC Science & Technology

2012-10-01

5.5 µg BMP-2, it was largely disorganized, woven bone with non-osseous soft tissue interspersed. The highest 4 dose (11 µg) of BMP-2, in contrast...various doses of BMP-2. Top row: 16x magnification Bottom row: 100x magnification N= new cortex M= marrow T=trabecular bone F= fibrous tissue ...areas of cartilagenous tissue (figure 5) it was clear that substantial areas of cartilage remained in the defects treated with 5.5 µg BMP-2. These may

Lethal Progressive Thoracic Insufficiency in a Neonate Due to Jarcho Levin Syndrome

PubMed Central

Bhutia, Euden; Maria, Arti; Verma, Arushi; Sethi, Sidharth Kumar

2014-01-01

A rare case of Jarcho Levin syndrome (JLS) presenting as a lethal progressive respiratory insufficiency in early neonatal period is reported. The neonate had classical features of this syndrome including vertebral segmentation defects, typical costo-vertebral fusion defects and scoliosis resulting in small thoracic volume and limited chest expansion; all consistent with a clinical diagnosis of JLS with thoracic insufficiency. In addition, our case had a rare association of dextrocardia and acyanotic congenital heart disease. PMID:24741543

Effect of Processing Conditions on the Anelastic Behavior of Plasma Sprayed Thermal Barrier Coatings

NASA Astrophysics Data System (ADS)

Viswanathan, Vaishak

2011-12-01

Plasma sprayed ceramic materials contain an assortment of micro-structural defects, including pores, cracks, and interfaces arising from the droplet based assemblage of the spray deposition technique. The defective architecture of the deposits introduces a novel "anelastic" response in the coatings comprising of their non-linear and hysteretic stress-strain relationship under mechanical loading. It has been established that this anelasticity can be attributed to the relative movement of the embedded defects under varying stresses. While the non-linear response of the coatings arises from the opening/closure of defects, hysteresis is produced by the frictional sliding among defect surfaces. Recent studies have indicated that anelastic behavior of coatings can be a unique descriptor of their mechanical behavior and related to the defect configuration. In this dissertation, a multi-variable study employing systematic processing strategies was conducted to augment the understanding on various aspects of the reported anelastic behavior. A bi-layer curvature measurement technique was adapted to measure the anelastic properties of plasma sprayed ceramic. The quantification of anelastic parameters was done using a non-linear model proposed by Nakamura et.al. An error analysis was conducted on the technique to know the available margins for both experimental as well as computational errors. The error analysis was extended to evaluate its sensitivity towards different coating microstructure. For this purpose, three coatings with significantly different microstructures were fabricated via tuning of process parameters. Later the three coatings were also subjected to different strain ranges systematically, in order to understand the origin and evolution of anelasticity on different microstructures. The last segment of this thesis attempts to capture the intricacies on the processing front and tries to evaluate and establish a correlation between them and the anelastic parameters.

49 CFR 195.230 - Welds: Repair or removal of defects.

Code of Federal Regulations, 2012 CFR

2012-10-01

... adversely affect the quality of the weld repair. After repair, the segment of the weld that was repaired... welding procedure used to make the original weld are met upon completion of the final weld repair. [Amdt...

49 CFR 195.230 - Welds: Repair or removal of defects.

Code of Federal Regulations, 2014 CFR

2014-10-01

... adversely affect the quality of the weld repair. After repair, the segment of the weld that was repaired... welding procedure used to make the original weld are met upon completion of the final weld repair. [Amdt...

49 CFR 195.230 - Welds: Repair or removal of defects.

Code of Federal Regulations, 2011 CFR

2011-10-01

... adversely affect the quality of the weld repair. After repair, the segment of the weld that was repaired... welding procedure used to make the original weld are met upon completion of the final weld repair. [Amdt...

49 CFR 195.230 - Welds: Repair or removal of defects.

Code of Federal Regulations, 2013 CFR

2013-10-01

... adversely affect the quality of the weld repair. After repair, the segment of the weld that was repaired... welding procedure used to make the original weld are met upon completion of the final weld repair. [Amdt...

49 CFR 195.230 - Welds: Repair or removal of defects.

Code of Federal Regulations, 2010 CFR

2010-10-01

... adversely affect the quality of the weld repair. After repair, the segment of the weld that was repaired... welding procedure used to make the original weld are met upon completion of the final weld repair. [Amdt...

Dual-threshold segmentation using Arimoto entropy based on chaotic bee colony optimization

NASA Astrophysics Data System (ADS)

Li, Li

2018-03-01

In order to extract target from complex background more quickly and accurately, and to further improve the detection effect of defects, a method of dual-threshold segmentation using Arimoto entropy based on chaotic bee colony optimization was proposed. Firstly, the method of single-threshold selection based on Arimoto entropy was extended to dual-threshold selection in order to separate the target from the background more accurately. Then intermediate variables in formulae of Arimoto entropy dual-threshold selection was calculated by recursion to eliminate redundant computation effectively and to reduce the amount of calculation. Finally, the local search phase of artificial bee colony algorithm was improved by chaotic sequence based on tent mapping. The fast search for two optimal thresholds was achieved using the improved bee colony optimization algorithm, thus the search could be accelerated obviously. A large number of experimental results show that, compared with the existing segmentation methods such as multi-threshold segmentation method using maximum Shannon entropy, two-dimensional Shannon entropy segmentation method, two-dimensional Tsallis gray entropy segmentation method and multi-threshold segmentation method using reciprocal gray entropy, the proposed method can segment target more quickly and accurately with superior segmentation effect. It proves to be an instant and effective method for image segmentation.

Modeling guided wave propagation in curved thick composites with ply drops and marcelling

NASA Astrophysics Data System (ADS)

Hakoda, Christopher; Choi, Gloria; Lissenden, Clifford

2018-04-01

Setting the process parameters for fabrication of thick composites having complex geometries is a challenging endeavor, with the best result being a high-quality part and less desirable results being parts that contain voids or fiber marcelling. An equal challenge is the nondestructive testing of these parts. Consider a U-shaped portion of a more complex part. The straight segments of the U-shape are approximately 10-mm thick, but a series of ply-drops reduce the thickness by one half at the center portion. Ultrasonic guided waves that have the potential to nondestructively test this part can be actuated by coupling transducers to the straight segments if and only if wave modes that are sensitive to the defects of interest can propagate through the ply drops, the curve, and the attenuation due to internal damping. A frequency domain finite element approach proposed in recent years for guided wave analysis is applied to this inhomogeneous waveguide problem in order to select modes and frequencies that are sensitive to marcelling.

Bilateral anterior segment dysgenesis with the presumed Peters' anomaly in a cat.

PubMed

Park, Sangwan; Kim, Kiwoong; Kim, Youngbeum; Seo, Kangmoon

2018-02-20

A seven-month-old female domestic shorthaired cat was presented for buphthalmos in the right eye and corneal cloudiness in the left eye. Full ophthalmic examinations were performed for both eyes and enucleation was done for the right nonvisual eye. Congenital glaucoma caused by anterior segment dysgenesis was confirmed for the right eye. In the left eye, slit-lamp examination revealed focal corneal edema with several iris strands from iris collarette to the affected posterior corneal surfaces. Circular posterior corneal defect was suggested to be the cause of edema. Goniodysgenesis, additionally, was identified. Taken together, the diagnosis of Peters' anomaly which is a subtype of anterior segment dysgenesis was suggested in the left eye.

Acute insulin resistance in ST-segment elevation myocardial infarction in non-diabetic patients is associated with incomplete myocardial reperfusion and impaired coronary microcirculatory function

PubMed Central

2014-01-01

Background Insulin resistance (IR) assessed by the Homeostatic Model Assessment (HOMA) index in the acute phase of myocardial infarction in non-diabetic patients was recently established as an independent predictor of intrahospital mortality. In this study we postulated that acute IR is a dynamic phenomenon associated with the development of myocardial and microvascular injury and larger final infarct size in patients with ST-segment elevation myocardial infarction (STEMI) treated by primary percutaneous coronary intervention (pPCI). Methods In 104 consecutive patients with the first anterior STEMI without diabetes, the HOMA index was determined on the 2nd and 7th day after pPCI. Worst-lead residual ST-segment elevation (ST-E) on postprocedural ECG, coronary flow reserve (CFR) determined by transthoracic Doppler echocardiography on the 2nd day after pPCI and fixed perfusion defect on single-photon emission computed tomography myocardial perfusion imaging (SPECT-MPI) determined six weeks after pPCI were analyzed according to HOMA indices. Results IR was present in 55 % and 58 % of patients on day 2 and day 7, respectively. Incomplete post-procedural ST-E resolution was more frequent in patients with IR compared to patients without IR, both on day 2 (p = 0.001) and day 7 (p < 0.001). The HOMA index on day 7 correlated with SPECT-MPI perfusion defect (r = 0.331), whereas both HOMA indices correlated well with CFR (r = -0.331 to -0.386) (p < 0.01 for all). In multivariable backward logistic regression analysis adjusted for significant univariate predictors and potential confounding variables, IR on day 2 was an independent predictor of residual ST-E ≥ 2 mm (OR 11.70, 95% CI 2.46-55.51, p = 0.002) and CFR < 2 (OR = 5.98, 95% CI 1.88-19.03, p = 0.002), whereas IR on day 7 was an independent predictor of SPECT-MPI perfusion defect > 20% (OR 11.37, 95% CI 1.34-96.21, p = 0.026). Conclusion IR assessed by the HOMA index during the acute phase of the first anterior STEMI in patients without diabetes treated by pPCI is independently associated with poorer myocardial reperfusion, impaired coronary microcirculatory function and potentially with larger final infarct size. PMID:24708817

Mutation update of transcription factor genes FOXE3, HSF4, MAF, and PITX3 causing cataracts and other developmental ocular defects.

PubMed

Anand, Deepti; Agrawal, Smriti A; Slavotinek, Anne; Lachke, Salil A

2018-04-01

Mutations in the transcription factor genes FOXE3, HSF4, MAF, and PITX3 cause congenital lens defects including cataracts that may be accompanied by defects in other components of the eye or in nonocular tissues. We comprehensively describe here all the variants in FOXE3, HSF4, MAF, and PITX3 genes linked to human developmental defects. A total of 52 variants for FOXE3, 18 variants for HSF4, 20 variants for MAF, and 19 variants for PITX3 identified so far in isolated cases or within families are documented. This effort reveals FOXE3, HSF4, MAF, and PITX3 to have 33, 16, 18, and 7 unique causal mutations, respectively. Loss-of-function mutant animals for these genes have served to model the pathobiology of the associated human defects, and we discuss the currently known molecular function of these genes, particularly with emphasis on their role in ocular development. Finally, we make the detailed FOXE3, HSF4, MAF, and PITX3 variant information available in the Leiden Online Variation Database (LOVD) platform at https://www.LOVD.nl/FOXE3, https://www.LOVD.nl/HSF4, https://www.LOVD.nl/MAF, and https://www.LOVD.nl/PITX3. Thus, this article informs on key variants in transcription factor genes linked to cataract, aphakia, corneal opacity, glaucoma, microcornea, microphthalmia, anterior segment mesenchymal dysgenesis, and Ayme-Gripp syndrome, and facilitates their access through Web-based databases. © 2018 Wiley Periodicals, Inc.

Segmental Mirroring: Does It Eliminate the Need for Intraoperative Readjustment of the Virtually Pre-Bent Reconstruction Plates and Is It Economically Valuable?

PubMed

Khalifa, Ghada Amin; Abd El Moniem, Nahed Adly; Elsayed, Shadia Abd-ElHameed; Qadry, Yara

2016-03-01

The aim of this study was to compare segmental mirroring with mirroring of the entire unaffected side to determine which method obviates intraoperative readjustment of virtually planned pre-bent plates and to evaluate the effect on costs. Patients eligible for inclusion in this prospective study had unilateral mandibular discontinuity defects. Patients were randomly divided into 2 groups. In group I, models were constructed by mirroring the entire unaffected side of the mandible at the midsagittal plane. In group II, only the resected segments were cut and replaced by the corresponding mirrored healthy segments. The lesions were resected, and their sites were reconstructed using pre-bent reconstruction plates. The need for intraoperative plate readjustment, plate placement time, operation time, and operation costs were reviewed. Fifty patients were enrolled in this study. All but 5 plates in group I required readjustment. In group II, plates were placed without intraoperative handling. Average operating times were 4.20 ± 0.56 hours in group I and 3.186 ± 0.28 hours in group II (P = .00002). Mean times for plate placement were 33.36 ± 8.20 and 21.88 ± 5.73 minutes in groups I and II, respectively. The difference resulted in an average time gain of 11.48 minutes. Average personal costs per minute were US$740.77 for group I and US$560.87 for group II. The difference resulted in an average saving of approximately US$179.90. Segmental mirroring is superior in reflecting the bone anatomy in 3-dimensional models, thus eliminating intraoperative plate readjustment and providing better plate adaptation with better contour. It decreases operating time and costs and thus can be recommended for lesions that do not cross the midline. Copyright © 2016 American Association of Oral and Maxillofacial Surgeons. Published by Elsevier Inc. All rights reserved.

Automated identification and indexing of dislocations in crystal interfaces

DOE PAGES

Stukowski, Alexander; Bulatov, Vasily V.; Arsenlis, Athanasios

2012-10-31

Here, we present a computational method for identifying partial and interfacial dislocations in atomistic models of crystals with defects. Our automated algorithm is based on a discrete Burgers circuit integral over the elastic displacement field and is not limited to specific lattices or dislocation types. Dislocations in grain boundaries and other interfaces are identified by mapping atomic bonds from the dislocated interface to an ideal template configuration of the coherent interface to reveal incompatible displacements induced by dislocations and to determine their Burgers vectors. Additionally, the algorithm generates a continuous line representation of each dislocation segment in the crystal andmore » also identifies dislocation junctions.« less

Development of a Novel Segmental Bone Defect Construct

DTIC Science & Technology

2016-10-01

from chicken egg white (90%) were purchased from Sigma Aldrich (St. Louis, MO). Ethylene glycol, sodium metabisulfite (SMS), urea, and hydrogen...HRP-conjugated polyclonal anti-LYZ (chicken egg white) was purchased from United States Biological (Swampscott, MA). N-(3-Sulfopropyl)- N

Identification of a Recurrent Microdeletion at 17q23.1q23.2 Flanked by Segmental Duplications Associated with Heart Defects and Limb Abnormalities

PubMed Central

Ballif, Blake C.; Theisen, Aaron; Rosenfeld, Jill A.; Traylor, Ryan N.; Gastier-Foster, Julie; Thrush, Devon Lamb; Astbury, Caroline; Bartholomew, Dennis; McBride, Kim L.; Pyatt, Robert E.; Shane, Kate; Smith, Wendy E.; Banks, Valerie; Gallentine, William B.; Brock, Pamela; Rudd, M. Katharine; Adam, Margaret P.; Keene, Julia A.; Phillips, John A.; Pfotenhauer, Jean P.; Gowans, Gordon C.; Stankiewicz, Pawel; Bejjani, Bassem A.; Shaffer, Lisa G.

2010-01-01

Segmental duplications, which comprise ∼5%–10% of the human genome, are known to mediate medically relevant deletions, duplications, and inversions through nonallelic homologous recombination (NAHR) and have been suggested to be hot spots in chromosome evolution and human genomic instability. We report seven individuals with microdeletions at 17q23.1q23.2, identified by microarray-based comparative genomic hybridization (aCGH). Six of the seven deletions are ∼2.2 Mb in size and flanked by large segmental duplications of >98% sequence identity and in the same orientation. One of the deletions is ∼2.8 Mb in size and is flanked on the distal side by a segmental duplication, whereas the proximal breakpoint falls between segmental duplications. These characteristics suggest that NAHR mediated six out of seven of these rearrangements. These individuals have common features, including mild to moderate developmental delay (particularly speech delay), microcephaly, postnatal growth retardation, heart defects, and hand, foot, and limb abnormalities. Although all individuals had at least mild dysmorphic facial features, there was no characteristic constellation of features that would elicit clinical suspicion of a specific disorder. The identification of common clinical features suggests that microdeletions at 17q23.1q23.2 constitute a novel syndrome. Furthermore, the inclusion in the minimal deletion region of TBX2 and TBX4, transcription factors belonging to a family of genes implicated in a variety of developmental pathways including those of heart and limb, suggests that these genes may play an important role in the phenotype of this emerging syndrome. PMID:20206336

Self-organizing neural network models for visual pattern recognition.

PubMed

Fukushima, K

1987-01-01

Two neural network models for visual pattern recognition are discussed. The first model, called a "neocognitron", is a hierarchical multilayered network which has only afferent synaptic connections. It can acquire the ability to recognize patterns by "learning-without-a-teacher": the repeated presentation of a set of training patterns is sufficient, and no information about the categories of the patterns is necessary. The cells of the highest stage eventually become "gnostic cells", whose response shows the final result of the pattern-recognition of the network. Pattern recognition is performed on the basis of similarity in shape between patterns, and is not affected by deformation, nor by changes in size, nor by shifts in the position of the stimulus pattern. The second model has not only afferent but also efferent synaptic connections, and is endowed with the function of selective attention. The afferent and the efferent signals interact with each other in the hierarchical network: the efferent signals, that is, the signals for selective attention, have a facilitating effect on the afferent signals, and at the same time, the afferent signals gate efferent signal flow. When a complex figure, consisting of two patterns or more, is presented to the model, it is segmented into individual patterns, and each pattern is recognized separately. Even if one of the patterns to which the models is paying selective attention is affected by noise or defects, the model can "recall" the complete pattern from which the noise has been eliminated and the defects corrected.

The fixation effect of a silk fibroin-bacterial cellulose composite plate in segmental defects of the zygomatic arch: an experimental study.

PubMed

Lee, Jung Min; Kim, Ji Heui; Lee, Ok Joo; Park, Chan Hum

2013-06-01

Bioresorbable fixation systems have been popular for the treatment of facial fractures. However, their mechanical properties are uncertain and complications have been reported. To overcome these problems, we developed a bioresorbable fixation plate using a composite of silk fibroin and bacterial cellulose (SF-BC) with biodegradability and increased biocompatibility. To investigate the regenerative effect of the bioresorbable SF-BC fixation plate on zygomatic arch defects in rats. In vivo animal study. The SF-BC composite plate had a tensile strength similar to that of a polylactic acid plate and a tight, pore-free microstructure. Bilateral segmental bone defects (2 mm in length) were created in the zygomatic arches of adult rats. One side was fixed with the SF-BC composite plate, and the other side was left without fixation. Academic research laboratory. Fifteen adult Sprague-Dawley rats. Fixation of the zygomatic arch defect with the SF-BC composite plate. Micro-computed tomography and histological evaluation of bone samples. Gross inspection revealed no specific complication. At 1, 2, 4, and 8 postoperative weeks, the zygomatic arches were explored by micro-computed tomography and histological examination. Control sides did not heal completely and showed bony degeneration and necrosis during the 8-week follow-up. However, we observed new bone formation in sides treated with the SF-BC composite plate, and bony defects were completely healed within 8 weeks. The SF-BC composite plate is a potential candidate for a new bioresorbable fixation system. Our composite material could considerably shorten bone regeneration time. Additional study of the control of biodegradability and mechanical properties of SF-BC composite plates and a comparative study with the resorbable plates currently in use should be undertaken.

CD22ΔE12 as a molecular target for corrective repair using a RNA trans-splicing strategy: Anti-leukemic activity of a rationally designed RNA trans-splicing molecule

PubMed Central

Uckun, Fatih M.; Qazi, Sanjive; Ma, Hong; Reaman, Gregory H.; Mitchell, Lloyd G.

2015-01-01

Our recent studies have demonstrated that the CD22 exon 12 deletion (CD22ΔE12) is a characteristic genetic defect of therapy-refractory clones in pediatric B-precursor acute lymphoblastic leukemia (BPL) and implicated the CD22ΔE12 genetic defect in the aggressive biology of relapsed or therapy-refractory pediatric BPL. The purpose of the present study was to further evaluate the biologic significance of the CD22ΔE12 molecular lesion and determine if it could serve as a molecular target for corrective repair using RNA trans-splicing therapy. We show that both pediatric and adult B-lineage lymphoid malignancies are characterized by a very high incidence of the CD22ΔE12 genetic defect. We provide experimental evidence that the correction of the CD22ΔE12 genetic defect in human CD22ΔE12+ BPL cells using a rationally designed CD22 RNA trans-splicing molecule (RTM) caused a pronounced reduction of their clonogenicity. The RTM-mediated correction replaced the downstream mutation-rich segment of Intron 12 and remaining segments of the mutant CD22 pre-mRNA with wildtype CD22 Exons 10-14, thereby preventing the generation of the cis-spliced aberrant CD22ΔE12 product. The anti-leukemic activity of this RTM against BPL xenograft clones derived from CD22ΔE12+ leukemia patients provides the preclinical proof-of-concept that correcting the CD22ΔE12 defect with rationally designed CD22 RTMs may provide the foundation for therapeutic innovations that are needed for successful treatment of high-risk and relapsed BPL patients. PMID:25567759

Quantitative analysis of hyperpolarized 129Xe ventilation imaging in healthy volunteers and subjects with chronic obstructive pulmonary disease

PubMed Central

Virgincar, Rohan S.; Cleveland, Zackary I.; Kaushik, S. Sivaram; Freeman, Matthew S.; Nouls, John; Cofer, Gary P.; Martinez-Jimenez, Santiago; He, Mu; Kraft, Monica; Wolber, Jan; McAdams, H. Page; Driehuys, Bastiaan

2013-01-01

In this study, hyperpolarized (HP) 129Xe MR ventilation and 1H anatomical images were obtained from 3 subject groups: young healthy volunteers (HV), subjects with chronic obstructive pulmonary disease (COPD), and age-matched control subjects (AMC). Ventilation images were quantified by 2 methods: an expert reader-based ventilation defect score percentage (VDS%) and a semi-automatic segmentation-based ventilation defect percentage (VDP). Reader-based values were assigned by two experienced radiologists and resolved by consensus. In the semi-automatic analysis, 1H anatomical images and 129Xe ventilation images were both segmented following registration, to obtain the thoracic cavity volume (TCV) and ventilated volume (VV), respectively, which were then expressed as a ratio to obtain the VDP. Ventilation images were also characterized by generating signal intensity histograms from voxels within the TCV, and heterogeneity was analyzed using the coefficient of variation (CV). The reader-based VDS% correlated strongly with the semi-automatically generated VDP (r = 0.97, p < 0.0001), and with CV (r = 0.82, p < 0.0001). Both 129Xe ventilation defect scoring metrics readily separated the 3 groups from one another and correlated significantly with FEV1 (VDS%: r = -0.78, p = 0.0002; VDP: r = -0.79, p = 0.0003; CV: r = -0.66, p = 0.0059) and other pulmonary function tests. In the healthy subject groups (HV and AMC), the prevalence of ventilation defects also increased with age (VDS%: r = 0.61, p = 0.0002; VDP: r = 0.63, p = 0.0002). Moreover, ventilation histograms and their associated CVs distinguished between COPD subjects with similar ventilation defect scores but visibly different ventilation patterns. PMID:23065808

Spatial Variation in Mobility-Lifetime Product in Bulk TlBr and CZT

NASA Astrophysics Data System (ADS)

Phillips, David; Haegel, Nancy; Blaine, Kevin; Kim, Hadong; Ciampi, Guido; Cirignano, Len

2012-02-01

The energy resolution of a semiconductor radiation detector depends on the charge transport properties of the semiconductor, and the mobility-lifetime (μτ) product is a key figure of merit for charge transport. In this work, we investigate the effects of two impurities, Na and Cu, on the μτ product in bulk thallium bromide (TlBr) using cathodoluminescence (CL) and transport imaging. Transport imaging uses a scanning electron microscope to generate a line of charge carriers on the surface of a bulk sample, and the intensity and spatial distribution of the recombination luminescence are recorded. A Green's function approach is used to model the generation, diffusion, and recombination of charge carriers under steady-state conditions. The luminescence distribution is fit to the model to extract the ambipolar diffusion length and the μτ product, providing a high-resolution correlation between the luminescence variations due to dopants/defects and the quantitative transport behavior. The μτ product has been mapped across a 40 μm segment of TlBr at a resolution of 2 μm. Additionally, this approach has been used to locally map variations in ambipolar diffusion length and μτ product due to extended defects in cadmium zinc telluride (CZT).

Multiscale modeling of dislocation-precipitate interactions in Fe: From molecular dynamics to discrete dislocations.

PubMed

Lehtinen, Arttu; Granberg, Fredric; Laurson, Lasse; Nordlund, Kai; Alava, Mikko J

2016-01-01

The stress-driven motion of dislocations in crystalline solids, and thus the ensuing plastic deformation process, is greatly influenced by the presence or absence of various pointlike defects such as precipitates or solute atoms. These defects act as obstacles for dislocation motion and hence affect the mechanical properties of the material. Here we combine molecular dynamics studies with three-dimensional discrete dislocation dynamics simulations in order to model the interaction between different kinds of precipitates and a 1/2〈111〉{110} edge dislocation in BCC iron. We have implemented immobile spherical precipitates into the ParaDis discrete dislocation dynamics code, with the dislocations interacting with the precipitates via a Gaussian potential, generating a normal force acting on the dislocation segments. The parameters used in the discrete dislocation dynamics simulations for the precipitate potential, the dislocation mobility, shear modulus, and dislocation core energy are obtained from molecular dynamics simulations. We compare the critical stresses needed to unpin the dislocation from the precipitate in molecular dynamics and discrete dislocation dynamics simulations in order to fit the two methods together and discuss the variety of the relevant pinning and depinning mechanisms.

Repair of facial nerve defects with decellularized artery allografts containing autologous adipose-derived stem cells in a rat model.

PubMed

Sun, Fei; Zhou, Ke; Mi, Wen-Juan; Qiu, Jian-Hua

2011-07-20

The purpose of this study was to investigate the effects of a decellularized artery allograft containing autologous adipose-derived stem cells (ADSCs) on an 8-mm facial nerve branch lesion in a rat model. At 8 weeks postoperatively, functional evaluation of unilateral vibrissae movements, morphological analysis of regenerated nerve segments and retrograde labeling of facial motoneurons were all analyzed. Better regenerative outcomes associated with functional improvement, great axonal growth, and improved target reinnervation were achieved in the artery-ADSCs group (2), whereas the cut nerves sutured with artery conduits alone (group 1) achieved inferior restoration. Furthermore, transected nerves repaired with nerve autografts (group 3) resulted in significant recovery of whisking, maturation of myelinated fibers and increased number of labeled facial neurons, and the latter two parameters were significantly different from those of group 2. Collectively, though our combined use of a decellularized artery allograft with autologous ADSCs achieved regenerative outcomes inferior to a nerve autograft, it certainly showed a beneficial effect on promoting nerve regeneration and thus represents an alternative approach for the reconstruction of peripheral facial nerve defects. Copyright © 2011 Elsevier Ireland Ltd. All rights reserved.

Comparison of the Cardiac MicroPET Images Obtained Using [(18)F]FPTP and [(13)N]NH3 in Rat Myocardial Infarction Models.

PubMed

Kim, Dong-Yeon; Kim, Hyeon Sik; Jang, Hwa Youn; Kim, Ju Han; Bom, Hee-Seung; Min, Jung-Joon

2014-10-09

The short half-life of current positron emission tomography (PET) cardiac tracers limits their widespread clinical use. We previously developed a (18)F-labeled phosphonium cation, [(18)F]FPTP, that demonstrated sharply defined myocardial defects in a corresponding infarcted myocardium. The aim of this study was to compare the image properties of PET scans obtained using [(18)F]FPTP with those obtained using [(13)N]NH3 in rat myocardial infarction models. Perfusion abnormality was analyzed in 17 segments of polar map images. The myocardium-to-liver and myocardium-to-lung ratios of [(18)F]FPTP were 10.48 and 2.65 times higher, respectively, than those of [(13)N]NH3 in images acquired 30 min after tracer injection. The myocardial defect size measured by [(18)F]FPTP correlated more closely with the hypoperfused area measured by quantitative 2,3,5-triphenyltetrazolium chloride staining (r = 0.89, P < 0.01) than did [(13)N]NH3 (r = 0.84, P < 0.01). [(18)F]FPTP might be useful as a replacement for the myocardial agent [(13)N]NH3 in cardiac PET/CT applications.

The anterior segment disorder autosomal dominant keratitis is linked to the Aniridia/PAX-6 gene

DOE Office of Scientific and Technical Information (OSTI.GOV)

Mirzayans, F.; Pearce, W.G.; Mah, T.S.

1994-09-01

Autosomal dominant keratitis (ADK) is an eye disease characterized by anterior stromal corneal opacification and vascularization in the peripheral cornea. Progression into the central cornea may compromise visual acuity. Other anterior segment features include minimal radial defects of the iris stroma. Posterior segment involvement is characterized by foveal hypoplasia with minimal effect on visual acuity. Aniridia is a second autosomal dominantly inherited ocular disorder defined by structural defects of the iris, frequently severe enough to cause an almost complete absence of iris. This may be accompanied by other anterior segment manifestations, including cataract and keratitis. Posterior segment involvement in aniridiamore » is characterized by foveal hypoplasia resulting in a highly variable impairment of visual acuity, often with nystagmus. Aniridia is usually inherited as an autosomal dominant disease and occurs in 1 in 50,000 to 100,000 people. Aniridia has been shown to result from mutations in PAX-6, a gene thought to regulate fetal eye development. The similar clinical findings in ADK and aniridia, with the similar patterns of inheritance, compelled us to investigate if these two ocular disorders are variants of the same genetic disorder. We have tested for linkage between PAX-6 and ADK within an ADK family with 33 members over four generations, including 11 affected individuals. Linkage studies reveal that D11S914 (located within 3 cM of PAX-6) does not recombine with ADK (LOD score 3.61; {theta} = 0.00), consistent with PAX-6 mutations being responsible for ADK. Direct sequencing of PAX-6 RT-PCR products from ADK patients is underway to identify the mutation within the PAX-6 gene that results in ADK. The linkage of PAX-6 with ADK, along with a recent report that mutations in PAX-6 also underlie Peter`s anomaly, implicates PAX-6 widely in anterior segment malformations.« less

Late-Onset Cone Photoreceptor Degeneration Induced by R172W Mutation in Rds and Partial Rescue by Gene Supplementation

PubMed Central

Conley, Shannon; Nour, May; Fliesler, Steven J.; Naash, Muna I.

2008-01-01

Purpose R172W is a common mutation in the human retinal degeneration slow (RDS) gene, associated with a late-onset dominant macular dystrophy. In this study, the authors characterized a mouse model that closely mimics the human phenotype and tested the feasibility of gene supplementation as a disease treatment strategy. Methods Transgenic mouse lines carrying the R172W mutation were generated. The retinal phenotype associated with this mutation in a low-expresser line (L-R172W) was examined, both structurally (histology with correlative immunohistochemistry) and functionally (electroretinography). By examining animals over time and with various rds genetic backgrounds, the authors evaluated the dominance of the defect. To assess the efficacy of gene transfer therapy as a treatment for this defect, a previously characterized transgenic line expressing the normal mouse peripherin/Rds (NMP) was crossed with a higher-expresser Rds line harboring the R172W mutation (H-R172W). Functional, structural, and biochemical analyses were used to assess rescue of the retinal disease phenotype. Results In the wild-type (WT) background, L-R172W mice exhibited late-onset (12-month) dominant cone degeneration without any apparent effect on rods. The degeneration was slightly accelerated (9 months) in the rds+/− background. L-R172W retinas did not form outer segments in the absence of endogenous Rds. With use of the H-R172W line on an rds+/− background for proof-of-principle genetic supplementation studies, the NMP transgene product rescued rod and cone functional defects and supported outer segment integrity up to 3 months of age, but the rescue effect did not persist in older (11-month) animals. Conclusions The R172W mutation leads to dominant cone degeneration in the mouse model, regardless of the expression level of the transgene. In contrast, effects of the mutation on rods are dose dependent, underscoring the usefulness of the L-R172W line as a faithful model of the human phenotype. This model may prove helpful in future studies on the mechanisms of cone degeneration and for elucidating the different roles of Rds in rods and cones. This study provides evidence that Rds genetic supplementation can be used to partially rescue visual function. Although this strategy is capable of rescuing haplo-insufficiency, it does not rescue the long-term degeneration associated with a gain-of-function mutation. PMID:18055786

Effect of Escherichia coli-produced recombinant human bone morphogenetic protein 2 on the regeneration of canine segmental ulnar defects.

PubMed

Harada, Yasuji; Itoi, Takamasa; Wakitani, Shigeyuki; Irie, Hiroyuki; Sakamoto, Michiko; Zhao, Dongwei; Nezu, Yoshinori; Yogo, Takuya; Hara, Yasushi; Tagawa, Masahiro

2012-07-01

Because bone morphogenetic protein 2 gene transfected Escherichia coli (E-BMP-2) produce recombinant human BMP-2 (rhBMP-2) more efficiently than mammalian cells (Chinese hamster ovary [CHO]-BMP-2), they may be a more cost-effective source of rhBMP-2 for clinical use. However, use of E-BMP-2 for regenerating long bones in large animals has not been reported. In the current study, we evaluated the healing efficacy of E-BMP-2 in a canine model. We created 2.5-cm critical-size segmental ulnar defects in test animals, then implanted E-BMP-2 and 700 mg of artificial bone (beta-tricalcium phosphate; β-TCP) into the wounds. We examined the differential effects of 5 E-BMP-2 treatments (0, 35, 140, 560, and 2240 μg) across 5 experimental groups (control, BMP35, BMP140, BMP560, and BMP2240). Radiography and computed tomography were used to observe the regeneration process. The groups in which higher doses of E-BMP-2 were administered (BMP560 and BMP2240) displayed more pronounced bone regeneration; the regenerated tissues connected to the host bone, and the cross-sectional areas of the regenerated bone were larger than those of the originals. The groups in which lower doses of E-BMP-2 were administered (BMP35 and BMP140) experienced relatively less bone regeneration; furthermore, the regenerated tissues failed to connect to the host bone. In these groups, the cross-sectional areas of the regenerated bone were equal to or smaller than those of the originals. No regeneration was observed in the control group. These findings suggest that, like CHO-BMP-2, E-BMP-2 can be used for the regeneration of large defects in long bones and that its clinical use might decrease the cost of bone regeneration treatments.

Repair of segmental bone defects with bone marrow and BMP-2 adenovirus in the rabbit radius

NASA Astrophysics Data System (ADS)

Cheng, Lijia; Lu, Xiaofeng; Shi, Yujun; Li, Li; Xue, Jing; Zhang, Li; Xia, Jie; Wang, Yujia; Zhang, Xingdong; Bu, Hong

2012-12-01

Bone tissue engineering (BTE) is approached via implantation of autogenous mesenchymal stem cells (MSCs), marrow cells, or platelet-rich plasma, etc. To the contrary, gene therapy combining with the bone marrow (BM) has not been often reported. This study was performed to investigate whether a modified BTE method, that is, the BM and a recombinant human bone morphogenetic protein-2 adenovirus (Ad.hBMP-2) gene administering in hydroxyapatite/β-tricalcium phosphate (HA/β-TCP) ceramics could accelerate the healing of segmental defects in the rabbit radius. In our study, ceramics were immersed in the adenovirus overnight, and half an hour before surgery, autologous BM aspirates were thoroughly mixed with the ceramics; at the same time, a 15-mm radius defect was introduced in the bilateral forelimbs of all animals, after that, this defect was filled with the following: (1) Ad.hBMP-2 + HA/β-TCP + autologous BM (group 1); (2) HA/β-TCP + Ad.hBMP-2 (group 2); (3) HA/β-TCP alone (group 3); (4) an empty defect as a control (group 4). Histological observation and μ-CT analyses were performed on the specimens at weeks 2, 4, 8, and 12, respectively. In group 1, new bone was observed at week 4 and BM appeared at week 12, in groups 2 and 3, new bone was observed at week 8 and it was more mature at week 12, in contrast, the defect was not bridged in group 4 at week 12. The new bone area percentage in group 1 was significantly higher than that in groups 2 and 3. Our study indicated that BM combined with hBMP-2 adenovirus and porous ceramics could significantly increase the amount of newly formed bone. And this modified BTE method thus might have potentials in future clinical application.

SGLT2 Inhibitors: Glucotoxicity and Tumorigenesis Downstream the Renal Proximal Tubule?

PubMed

Bertinat, Romina; Nualart, Francisco; Yáñez, Alejandro J

2016-08-01

At present, diabetes mellitus is the main cause of end-stage renal disease. Effective glycaemic management is the most powerful tool to delay the establishment of diabetic complications, such as diabetic kidney disease. Together with reducing blood glucose levels, new anti-diabetic agents are expected not only to control the progression but also to restore known defects of the diabetic kidney. Sodium-glucose co-transporter 2 (SGLT2) inhibitors are promising anti-diabetic agents that reduce hyperglycaemia by impairing glucose reabsorption in proximal tubule of the kidney and increasing glucosuria. SGLT2 inhibitors have shown to reduce glucotoxicity in isolated proximal tubule cells and also to attenuate expression of markers of overall kidney damage in experimental animal models of diabetes, but the actual renoprotective effect for downstream nephron segments is still unknown and deserves further attention. Here, we briefly discuss possible undesired effects of enhanced glucosuria and albuminuria in nephron segments beyond the proximal tubule after SGLT2 inhibitor treatment, offering new lines of research to further understand the renoprotective action of these anti-diabetic agents. Strategies blocking glucose reabsorption by renal proximal tubule epithelial cells (RPTEC) may be protective for RPTEC, but downstream nephron segments will still be exposed to high glucose and albumin levels through the luminal face. The actual effect of constant enhanced glucosuria over distal nephron segments remains to be established. J. Cell. Physiol. 231: 1635-1637, 2016. © 2015 Wiley Periodicals, Inc. © 2015 Wiley Periodicals, Inc.

Single-Tooth Osteotomy Combined Wide Linear Corticotomy Under Local Anesthesia for Correcting Anterior Protrusion With Ectopically Erupted Canine.

PubMed

Iskenderoglu, Nur Serife; Choi, Byung-Joon; Seo, Kyung Won; Lee, Yeon-Ji; Lee, Baek-Soo; Kim, Seong-Hun

2017-01-01

This article presents the alternative surgical treatments of both anterior protrusion by carrying out retraction on mandibular anterior fragment, meanwhile applying retraction force on maxilla anterior teeth and ectopically erupted canine with using platelet-rich fibrin (PRF). Anterior segmental osteotomy was combined with linear corticotomy under local anesthesia. The correction of right ectopic canine was achieved through 2 stages. First, dento-osseous osteotomy on palatal side was performed. Then second osteotomy with immediate manual repositioning of the canine with concomitant first premolar extraction was enhanced with PRF, which was prepared by centrifuging patient's blood, applied into buccal side of high canine during osteotomy. Mandibular retraction was accomplished by anterior segmental osteotomy. Single-tooth osteotomy is a more effective surgical method for ankylosed or ectopically erupted tooth in orthodontic treatment. It can reduce the total orthodontic treatment time and root resorption, 1 common complication. Significant improved bone formation was seen with the addition of PRF on noncritical size defects in the animal model. It is reasonable to think that PRF can promote bone regeneration. So early bone formation also can reduce the complication such as postoperative infection. As an alternative to anterior protrusion and ectopically erupted canine treatment, segmental osteotomy and corticotomy combined platelet-rich plasma can enhance orthodontic treatment outcome.

High frequency QRS ECG predicts ischemic defects during myocardial perfusion imaging

NASA Technical Reports Server (NTRS)

2004-01-01

Changes in high frequency QRS components of the electrocardiogram (HF QRS ECG) (150-250 Hz) are more sensitive than changes in conventional ST segments for detecting myocardial ischemia. We investigated the accuracy of 12-lead HF QRS ECG in detecting ischemia during adenosine tetrofosmin myocardial perfusion imaging (MPI). 12-lead HF QRS ECG recordings were obtained from 45 patients before and during adenosine technetium-99 tetrofosmin MPI tests. Before the adenosine infusions, recordings of HF QRS were analyzed according to a morphological score that incorporated the number, type and location of reduced amplitude zones (RAZs) present in the 12 leads. During the adenosine infusions, recordings of HF QRS were analyzed according to the maximum percentage changes (in both the positive and negative directions) that occurred in root mean square (RMS) voltage amplitudes within the 12 leads. The best set of prospective HF QRS criteria had a sensitivity of 94% and a specificity of 83% for correctly identifying the MPI result. The sensitivity of simultaneous ST segment changes (18%) was significantly lower than that of any individual HF QRS criterion (P less than 0.00l). Analysis of 12-lead HF QRS ECG is highly sensitive and specific for detecting ischemic perfusion defects during adenosine MPI stress tests and significantly more sensitive than analysis of conventional ST segments.

High frequency QRS ECG predicts ischemic defects during myocardial perfusion imaging

NASA Technical Reports Server (NTRS)

Rahman, Atiar

2006-01-01

Background: Changes in high frequency QRS components of the electrocardiogram (HF QRS ECG) (150-250 Hz) are more sensitive than changes in conventional ST segments for detecting myocardial ischemia. We investigated the accuracy of 12-lead HF QRS ECG in detecting ischemia during adenosine tetrofosmin myocardial perfusion imaging (MPI). Methods and Results: 12-lead HF QRS ECG recordings were obtained from 45 patients before and during adenosine technetium-99 tetrofosmin MPI tests. Before the adenosine infusions, recordings of HF QRS were analyzed according to a morphological score that incorporated the number, type and location of reduced amplitude zones (RAZs) present in the 12 leads. During the adenosine infusions, recordings of HF QRS were analyzed according to the maximum percentage changes (in both the positive and negative directions) that occurred in root mean square (RMS) voltage amplitudes within the 12 leads. The best set of prospective HF QRS criteria had a sensitivity of 94% and a specificity of 83% for correctly identifying the MPI result. The sensitivity of simultaneous ST segment changes (18%) was significantly lower than that of any individual HF QRS criterion (P<0.001). Conclusions: Analysis of 12-lead HF QRS ECG is highly sensitive and specific for detecting ischemic perfusion defects during adenosine MPI stress tests and significantly more sensitive than analysis of conventional ST segments.

One-stage reconstruction of the complex midfoot defect with a multiple osteotomized free fibular osteocutaneous flap: case report and literature review.

PubMed

Lykoudis, Efstathios G; Dimitrios, Pafilas; Alexandros, Beris E

2010-01-01

Complex midfoot defects represent a reconstructive challenge since midfoot plays a key role in standing and gait. We report the case of a 27-year-old patient with a complex midfoot defect due to a high-energy gun shot injury. The defect included the tarsometatarsal complex, all three arches of the foot, and the overlying dorsal skin of the foot. Reconstruction was achieved in a single stage with a free fibular osteocutaneous flap. The fibula was osteotomized into three segments, which were used to reconstruct the bone defects, while the skin paddle of the flap was used for stable soft tissue coverage of the reconstructed bony skeleton. Early and late postoperative periods were uneventful. Bone incorporation was radiographically evident at 12 weeks, and full weight bearing was possible at 6 months postop. Final follow up, at 2 years postop, showed a very good functional and esthetic outcome.

A tissue engineering solution for segmental defect regeneration in load-bearing long bones.

PubMed

Reichert, Johannes C; Cipitria, Amaia; Epari, Devakara R; Saifzadeh, Siamak; Krishnakanth, Pushpanjali; Berner, Arne; Woodruff, Maria A; Schell, Hanna; Mehta, Manav; Schuetz, Michael A; Duda, Georg N; Hutmacher, Dietmar W

2012-07-04

The reconstruction of large defects (>10 mm) in humans usually relies on bone graft transplantation. Limiting factors include availability of graft material, comorbidity, and insufficient integration into the damaged bone. We compare the gold standard autograft with biodegradable composite scaffolds consisting of medical-grade polycaprolactone and tricalcium phosphate combined with autologous bone marrow-derived mesenchymal stem cells (MSCs) or recombinant human bone morphogenetic protein 7 (rhBMP-7). Critical-sized defects in sheep--a model closely resembling human bone formation and structure--were treated with autograft, rhBMP-7, or MSCs. Bridging was observed within 3 months for both the autograft and the rhBMP-7 treatment. After 12 months, biomechanical analysis and microcomputed tomography imaging showed significantly greater bone formation and superior strength for the biomaterial scaffolds loaded with rhBMP-7 compared to the autograft. Axial bone distribution was greater at the interfaces. With rhBMP-7, at 3 months, the radial bone distribution within the scaffolds was homogeneous. At 12 months, however, significantly more bone was found in the scaffold architecture, indicating bone remodeling. Scaffolds alone or with MSC inclusion did not induce levels of bone formation comparable to those of the autograft and rhBMP-7 groups. Applied clinically, this approach using rhBMP-7 could overcome autograft-associated limitations.

Step-by-Step Technique for Segmental Reconstruction of Reverse Hill-Sachs Lesions Using Homologous Osteochondral Allograft.

PubMed

Alkaduhimi, Hassanin; van den Bekerom, Michel P J; van Deurzen, Derek F P

2017-06-01

Posterior shoulder dislocations are accompanied by high forces and can result in an anteromedial humeral head impression fracture called a reverse Hill-Sachs lesion. This reverse Hill-Sachs lesion can result in serious complications including posttraumatic osteoarthritis, posterior dislocations, osteonecrosis, persistent joint stiffness, and loss of shoulder function. Treatment is challenging and depends on the amount of bone loss. Several techniques have been reported to describe the surgical treatment of lesions larger than 20%. However, there is still limited evidence with regard to the optimal procedure. Favorable results have been reported by performing segmental reconstruction of the reverse Hill-Sachs lesion with bone allograft. Although the procedure of segmental reconstruction has been used in several studies, its technique has not yet been well described in detail. In this report we propose a step-by-step description of the technique how to perform a segmental reconstruction of a reverse Hill-Sachs defect.

Defect detection and classification of galvanized stamping parts based on fully convolution neural network

NASA Astrophysics Data System (ADS)

Xiao, Zhitao; Leng, Yanyi; Geng, Lei; Xi, Jiangtao

2018-04-01

In this paper, a new convolution neural network method is proposed for the inspection and classification of galvanized stamping parts. Firstly, all workpieces are divided into normal and defective by image processing, and then the defective workpieces extracted from the region of interest (ROI) area are input to the trained fully convolutional networks (FCN). The network utilizes an end-to-end and pixel-to-pixel training convolution network that is currently the most advanced technology in semantic segmentation, predicts result of each pixel. Secondly, we mark the different pixel values of the workpiece, defect and background for the training image, and use the pixel value and the number of pixels to realize the recognition of the defects of the output picture. Finally, the defect area's threshold depended on the needs of the project is set to achieve the specific classification of the workpiece. The experiment results show that the proposed method can successfully achieve defect detection and classification of galvanized stamping parts under ordinary camera and illumination conditions, and its accuracy can reach 99.6%. Moreover, it overcomes the problem of complex image preprocessing and difficult feature extraction and performs better adaptability.

Vision-based in-line fabric defect detection using yarn-specific shape features

NASA Astrophysics Data System (ADS)

Schneider, Dorian; Aach, Til

2012-01-01

We develop a methodology for automatic in-line flaw detection in industrial woven fabrics. Where state of the art detection algorithms apply texture analysis methods to operate on low-resolved ({200 ppi) image data, we describe here a process flow to segment single yarns in high-resolved ({1000 ppi) textile images. Four yarn shape features are extracted, allowing a precise detection and measurement of defects. The degree of precision reached allows a classification of detected defects according to their nature, providing an innovation in the field of automatic fabric flaw detection. The design has been carried out to meet real time requirements and face adverse conditions caused by loom vibrations and dirt. The entire process flow is discussed followed by an evaluation using a database with real-life industrial fabric images. This work pertains to the construction of an on-loom defect detection system to be used in manufacturing practice.

A Novel Defect Inspection Method for Semiconductor Wafer Based on Magneto-Optic Imaging

NASA Astrophysics Data System (ADS)

Pan, Z.; Chen, L.; Li, W.; Zhang, G.; Wu, P.

2013-03-01

The defects of semiconductor wafer may be generated from the manufacturing processes. A novel defect inspection method of semiconductor wafer is presented in this paper. The method is based on magneto-optic imaging, which involves inducing eddy current into the wafer under test, and detecting the magnetic flux associated with eddy current distribution in the wafer by exploiting the Faraday rotation effect. The magneto-optic image being generated may contain some noises that degrade the overall image quality, therefore, in this paper, in order to remove the unwanted noise present in the magneto-optic image, the image enhancement approach using multi-scale wavelet is presented, and the image segmentation approach based on the integration of watershed algorithm and clustering strategy is given. The experimental results show that many types of defects in wafer such as hole and scratch etc. can be detected by the method proposed in this paper.

Sparsity guided empirical wavelet transform for fault diagnosis of rolling element bearings

NASA Astrophysics Data System (ADS)

Wang, Dong; Zhao, Yang; Yi, Cai; Tsui, Kwok-Leung; Lin, Jianhui

2018-02-01

Rolling element bearings are widely used in various industrial machines, such as electric motors, generators, pumps, gearboxes, railway axles, turbines, and helicopter transmissions. Fault diagnosis of rolling element bearings is beneficial to preventing any unexpected accident and reducing economic loss. In the past years, many bearing fault detection methods have been developed. Recently, a new adaptive signal processing method called empirical wavelet transform attracts much attention from readers and engineers and its applications to bearing fault diagnosis have been reported. The main problem of empirical wavelet transform is that Fourier segments required in empirical wavelet transform are strongly dependent on the local maxima of the amplitudes of the Fourier spectrum of a signal, which connotes that Fourier segments are not always reliable and effective if the Fourier spectrum of the signal is complicated and overwhelmed by heavy noises and other strong vibration components. In this paper, sparsity guided empirical wavelet transform is proposed to automatically establish Fourier segments required in empirical wavelet transform for fault diagnosis of rolling element bearings. Industrial bearing fault signals caused by single and multiple railway axle bearing defects are used to verify the effectiveness of the proposed sparsity guided empirical wavelet transform. Results show that the proposed method can automatically discover Fourier segments required in empirical wavelet transform and reveal single and multiple railway axle bearing defects. Besides, some comparisons with three popular signal processing methods including ensemble empirical mode decomposition, the fast kurtogram and the fast spectral correlation are conducted to highlight the superiority of the proposed method.

Vessel formation is induced prior to the appearance of cartilage in BMP-2-mediated heterotopic ossification

USDA-ARS?s Scientific Manuscript database

Heterotopic ossification (HO), or endochondral bone formation at nonskeletal sites, often results from traumatic injury and can lead to devastating consequences. Alternatively, the ability to harness this phenomenon would greatly enhance current orthopedic tools for treating segmental bone defects. ...

Enhanced Healing of Segmental Bone Defects by Modulation of the Mechanical Environment

DTIC Science & Technology

2013-10-01

Employment opportunities received based upon experience/ training supported by this award Partly based upon her research during the completion of...School, Coventry CV4 7AL, United Kingdom References 1. Stevenson S. Enhancement of fracture healing with autogenous and allogeneic bone grafts. Clin

Simple rules for a "simple" nervous system? Molecular and biomathematical approaches to enteric nervous system formation and malformation.

PubMed

Newgreen, Donald F; Dufour, Sylvie; Howard, Marthe J; Landman, Kerry A

2013-10-01

We review morphogenesis of the enteric nervous system from migratory neural crest cells, and defects of this process such as Hirschsprung disease, centering on cell motility and assembly, and cell adhesion and extracellular matrix molecules, along with cell proliferation and growth factors. We then review continuum and agent-based (cellular automata) models with rules of cell movement and logistical proliferation. Both movement and proliferation at the individual cell level are modeled with stochastic components from which stereotyped outcomes emerge at the population level. These models reproduced the wave-like colonization of the intestine by enteric neural crest cells, and several new properties emerged, such as colonization by frontal expansion, which were later confirmed biologically. These models predict a surprising level of clonal heterogeneity both in terms of number and distribution of daughter cells. Biologically, migrating cells form stable chains made up of unstable cells, but this is not seen in the initial model. We outline additional rules for cell differentiation into neurons, axon extension, cell-axon and cell-cell adhesions, chemotaxis and repulsion which can reproduce chain migration. After the migration stage, the cells re-arrange as a network of ganglia. Changes in cell adhesion molecules parallel this, and we describe additional rules based on Steinberg's Differential Adhesion Hypothesis, reflecting changing levels of adhesion in neural crest cells and neurons. This was able to reproduce enteric ganglionation in a model. Mouse mutants with disturbances of enteric nervous system morphogenesis are discussed, and these suggest future refinement of the models. The modeling suggests a relatively simple set of cell behavioral rules could account for complex patterns of morphogenesis. The model has allowed the proposal that Hirschsprung disease is mostly an enteric neural crest cell proliferation defect, not a defect of cell migration. In addition, the model suggests an explanations for zonal and skip segment variants of Hirschsprung disease, and also gives a novel stochastic explanation for the observed discordancy of Hirschsprung disease in identical twins. © 2013 Elsevier Inc. All rights reserved.

3D printing and intraoperative neuronavigation tailoring for skull base reconstruction after extended endoscopic endonasal surgery: proof of concept.

PubMed

Essayed, Walid I; Unadkat, Prashin; Hosny, Ahmed; Frisken, Sarah; Rassi, Marcio S; Mukundan, Srinivasan; Weaver, James C; Al-Mefty, Ossama; Golby, Alexandra J; Dunn, Ian F

2018-03-02

OBJECTIVE Endoscopic endonasal approaches are increasingly performed for the surgical treatment of multiple skull base pathologies. Preventing postoperative CSF leaks remains a major challenge, particularly in extended approaches. In this study, the authors assessed the potential use of modern multimaterial 3D printing and neuronavigation to help model these extended defects and develop specifically tailored prostheses for reconstructive purposes. METHODS Extended endoscopic endonasal skull base approaches were performed on 3 human cadaveric heads. Preprocedure and intraprocedure CT scans were completed and were used to segment and design extended and tailored skull base models. Multimaterial models with different core/edge interfaces were 3D printed for implantation trials. A novel application of the intraoperative landmark acquisition method was used to transfer the navigation, helping to tailor the extended models. RESULTS Prostheses were created based on preoperative and intraoperative CT scans. The navigation transfer offered sufficiently accurate data to tailor the preprinted extended skull base defect prostheses. Successful implantation of the skull base prostheses was achieved in all specimens. The progressive flexibility gradient of the models' edges offered the best compromise for easy intranasal maneuverability, anchoring, and structural stability. Prostheses printed based on intraprocedure CT scans were accurate in shape but slightly undersized. CONCLUSIONS Preoperative 3D printing of patient-specific skull base models is achievable for extended endoscopic endonasal surgery. The careful spatial modeling and the use of a flexibility gradient in the design helped achieve the most stable reconstruction. Neuronavigation can help tailor preprinted prostheses.

Hierarchical Regularization of Polygons for Photogrammetric Point Clouds of Oblique Images

NASA Astrophysics Data System (ADS)

Xie, L.; Hu, H.; Zhu, Q.; Wu, B.; Zhang, Y.

2017-05-01

Despite the success of multi-view stereo (MVS) reconstruction from massive oblique images in city scale, only point clouds and triangulated meshes are available from existing MVS pipelines, which are topologically defect laden, free of semantical information and hard to edit and manipulate interactively in further applications. On the other hand, 2D polygons and polygonal models are still the industrial standard. However, extraction of the 2D polygons from MVS point clouds is still a non-trivial task, given the fact that the boundaries of the detected planes are zigzagged and regularities, such as parallel and orthogonal, cannot preserve. Aiming to solve these issues, this paper proposes a hierarchical polygon regularization method for the photogrammetric point clouds from existing MVS pipelines, which comprises of local and global levels. After boundary points extraction, e.g. using alpha shapes, the local level is used to consolidate the original points, by refining the orientation and position of the points using linear priors. The points are then grouped into local segments by forward searching. In the global level, regularities are enforced through a labeling process, which encourage the segments share the same label and the same label represents segments are parallel or orthogonal. This is formulated as Markov Random Field and solved efficiently. Preliminary results are made with point clouds from aerial oblique images and compared with two classical regularization methods, which have revealed that the proposed method are more powerful in abstracting a single building and is promising for further 3D polygonal model reconstruction and GIS applications.

Computer object segmentation by nonlinear image enhancement, multidimensional clustering, and geometrically constrained contour optimization

NASA Astrophysics Data System (ADS)

Bruynooghe, Michel M.

1998-04-01

In this paper, we present a robust method for automatic object detection and delineation in noisy complex images. The proposed procedure is a three stage process that integrates image segmentation by multidimensional pixel clustering and geometrically constrained optimization of deformable contours. The first step is to enhance the original image by nonlinear unsharp masking. The second step is to segment the enhanced image by multidimensional pixel clustering, using our reducible neighborhoods clustering algorithm that has a very interesting theoretical maximal complexity. Then, candidate objects are extracted and initially delineated by an optimized region merging algorithm, that is based on ascendant hierarchical clustering with contiguity constraints and on the maximization of average contour gradients. The third step is to optimize the delineation of previously extracted and initially delineated objects. Deformable object contours have been modeled by cubic splines. An affine invariant has been used to control the undesired formation of cusps and loops. Non linear constrained optimization has been used to maximize the external energy. This avoids the difficult and non reproducible choice of regularization parameters, that are required by classical snake models. The proposed method has been applied successfully to the detection of fine and subtle microcalcifications in X-ray mammographic images, to defect detection by moire image analysis, and to the analysis of microrugosities of thin metallic films. The later implementation of the proposed method on a digital signal processor associated to a vector coprocessor would allow the design of a real-time object detection and delineation system for applications in medical imaging and in industrial computer vision.

Small bowel obstruction caused by congenital transmesenteric defect.

PubMed

Nouira, F; Dhaou, Ben M; Charieg, A; Ghorbel, S; Jlidi, S; Chaouachi, B

2011-01-01

Transmesenteric hernias are extremely rare. A strangulated hernia through a mesenteric opening is a rare operative finding. Preoperative diagnosis still is difficult in spite of the imaging techniques currently available. The authors describe two cases of paediatric patients presenting with bowel obstruction resulting from a congenital mesenteric hernia. The first patient had a 3-cm wide congenital defect in the ileal mesentery through which the sigmoid colon had herniated. The second patient is a newborn infant who presented with symptoms and radiographic evidence of neonatal occlusion. At surgical exploration, a long segment of the small bowel had herniated in a defect in the ileal mesentery. A brief review of epidemiology and anatomy of transmesenteric hernias is included, along with a discussion of the difficulties in diagnosis and treatment of this condition.

Localization of Usher 1 proteins to the photoreceptor calyceal processes, which are absent from mice.

PubMed

Sahly, Iman; Dufour, Eric; Schietroma, Cataldo; Michel, Vincent; Bahloul, Amel; Perfettini, Isabelle; Pepermans, Elise; Estivalet, Amrit; Carette, Diane; Aghaie, Asadollah; Ebermann, Inga; Lelli, Andrea; Iribarne, Maria; Hardelin, Jean-Pierre; Weil, Dominique; Sahel, José-Alain; El-Amraoui, Aziz; Petit, Christine

2012-10-15

The mechanisms underlying retinal dystrophy in Usher syndrome type I (USH1) remain unknown because mutant mice lacking any of the USH1 proteins-myosin VIIa, harmonin, cadherin-23, protocadherin-15, sans-do not display retinal degeneration. We found here that, in macaque photoreceptor cells, all USH1 proteins colocalized at membrane interfaces (i) between the inner and outer segments in rods and (ii) between the microvillus-like calyceal processes and the outer segment basolateral region in rods and cones. This pattern, conserved in humans and frogs, was mediated by the formation of an USH1 protein network, which was associated with the calyceal processes from the early embryonic stages of outer segment growth onwards. By contrast, mouse photoreceptors lacked calyceal processes and had no USH1 proteins at the inner-outer segment interface. We suggest that USH1 proteins form an adhesion belt around the basolateral region of the photoreceptor outer segment in humans, and that defects in this structure cause the retinal degeneration in USH1 patients.

Localization of Usher 1 proteins to the photoreceptor calyceal processes, which are absent from mice

PubMed Central

Sahly, Iman; Dufour, Eric; Schietroma, Cataldo; Michel, Vincent; Bahloul, Amel; Perfettini, Isabelle; Pepermans, Elise; Estivalet, Amrit; Carette, Diane; Aghaie, Asadollah; Ebermann, Inga; Lelli, Andrea; Iribarne, Maria; Hardelin, Jean-Pierre; Weil, Dominique; Sahel, José-Alain

2012-01-01

The mechanisms underlying retinal dystrophy in Usher syndrome type I (USH1) remain unknown because mutant mice lacking any of the USH1 proteins—myosin VIIa, harmonin, cadherin-23, protocadherin-15, sans—do not display retinal degeneration. We found here that, in macaque photoreceptor cells, all USH1 proteins colocalized at membrane interfaces (i) between the inner and outer segments in rods and (ii) between the microvillus-like calyceal processes and the outer segment basolateral region in rods and cones. This pattern, conserved in humans and frogs, was mediated by the formation of an USH1 protein network, which was associated with the calyceal processes from the early embryonic stages of outer segment growth onwards. By contrast, mouse photoreceptors lacked calyceal processes and had no USH1 proteins at the inner–outer segment interface. We suggest that USH1 proteins form an adhesion belt around the basolateral region of the photoreceptor outer segment in humans, and that defects in this structure cause the retinal degeneration in USH1 patients. PMID:23045546

Mineralization Induction of Gingival Fibroblasts and Construction of a Sandwich Tissue-Engineered Complex for Repairing Periodontal Defects

PubMed Central

Wu, Mingxuan; Zhang, Yanning; Liu, Huijuan; Dong, Fusheng

2018-01-01

Background The ideal healing technique for periodontal tissue defects would involve the functional regeneration of the alveolar bone, cementum, and periodontal ligament, with new periodontal attachment formation. In this study, gingival fibroblasts were induced and a “sandwich” tissue-engineered complex (a tissue-engineered periodontal membrane between 2 tissue-engineered mineralized membranes) was constructed to repair periodontal defects. We evaluated the effects of gingival fibroblasts used as seed cells on the repair of periodontal defects and periodontal regeneration. Material/Methods Primitively cultured gingival fibroblasts were seeded bilaterally on Bio-Gide collagen membrane (a tissue-engineered periodontal membrane) or unilaterally on small intestinal submucosa segments, and their mineralization was induced. A tissue-engineered sandwich was constructed, comprising the tissue-engineered periodontal membrane flanked by 2 mineralized membranes. Periodontal defects in premolar regions of Beagles were repaired using the tissue-engineered sandwich or periodontal membranes. Periodontal reconstruction was compared to normal and trauma controls 10 or 20 days postoperatively. Results Periodontal defects were completely repaired by the sandwich tissue-engineered complex, with intact new alveolar bone and cementum, and a new periodontal ligament, 10 days postoperatively. Conclusions The sandwich tissue-engineered complex can achieve ideal periodontal reconstruction rapidly. PMID:29470454

Defect Detection in Textures through the Use of Entropy as a Means for Automatically Selecting the Wavelet Decomposition Level.

PubMed

Navarro, Pedro J; Fernández-Isla, Carlos; Alcover, Pedro María; Suardíaz, Juan

2016-07-27

This paper presents a robust method for defect detection in textures, entropy-based automatic selection of the wavelet decomposition level (EADL), based on a wavelet reconstruction scheme, for detecting defects in a wide variety of structural and statistical textures. Two main features are presented. One of the new features is an original use of the normalized absolute function value (NABS) calculated from the wavelet coefficients derived at various different decomposition levels in order to identify textures where the defect can be isolated by eliminating the texture pattern in the first decomposition level. The second is the use of Shannon's entropy, calculated over detail subimages, for automatic selection of the band for image reconstruction, which, unlike other techniques, such as those based on the co-occurrence matrix or on energy calculation, provides a lower decomposition level, thus avoiding excessive degradation of the image, allowing a more accurate defect segmentation. A metric analysis of the results of the proposed method with nine different thresholding algorithms determined that selecting the appropriate thresholding method is important to achieve optimum performance in defect detection. As a consequence, several different thresholding algorithms depending on the type of texture are proposed.

Quantitative assessment in thermal image segmentation for artistic objects

NASA Astrophysics Data System (ADS)

Yousefi, Bardia; Sfarra, Stefano; Maldague, Xavier P. V.

2017-07-01

The application of the thermal and infrared technology in different areas of research is considerably increasing. These applications involve Non-destructive Testing (NDT), Medical analysis (Computer Aid Diagnosis/Detection- CAD), Arts and Archaeology among many others. In the arts and archaeology field, infrared technology provides significant contributions in term of finding defects of possible impaired regions. This has been done through a wide range of different thermographic experiments and infrared methods. The proposed approach here focuses on application of some known factor analysis methods such as standard Non-Negative Matrix Factorization (NMF) optimized by gradient-descent-based multiplicative rules (SNMF1) and standard NMF optimized by Non-negative least squares (NNLS) active-set algorithm (SNMF2) and eigen decomposition approaches such as Principal Component Thermography (PCT), Candid Covariance-Free Incremental Principal Component Thermography (CCIPCT) to obtain the thermal features. On one hand, these methods are usually applied as preprocessing before clustering for the purpose of segmentation of possible defects. On the other hand, a wavelet based data fusion combines the data of each method with PCT to increase the accuracy of the algorithm. The quantitative assessment of these approaches indicates considerable segmentation along with the reasonable computational complexity. It shows the promising performance and demonstrated a confirmation for the outlined properties. In particular, a polychromatic wooden statue and a fresco were analyzed using the above mentioned methods and interesting results were obtained.

Analysis of selected volatile organic compounds in split and nonsplit swiss cheese samples using selected-ion flow tube mass spectrometry (SIFT-MS).

PubMed

Castada, Hardy Z; Wick, Cheryl; Taylor, Kaitlyn; Harper, W James

2014-04-01

Splits/cracks are recurring product defects that negatively affect the Swiss cheese industry. Investigations to understand the biophysicochemical aspects of these defects, and thus determine preventive measures against their occurrence, are underway. In this study, selected-ion, flow tube mass spectrometry was employed to determine the volatile organic compound (VOC) profiles present in the headspace of split compared with nonsplit cheeses. Two sampling methodologies were employed: split compared with nonsplit cheese vat pair blocks; and comparison of blind, eye, and split segments within cheese blocks. The variability in VOC profiles was examined to evaluate the potential biochemical pathway chemistry differences within and between cheese samples. VOC profile inhomogeneity was most evident in cheeses between factories. Evaluation of biochemical pathways leading to the formation of key VOCs differentiating the split from the blind and eye segments within factories indicated release of additional carbon dioxide by-product. These results suggest a factory-dependent cause of split formation that could develop from varied fermentation pathways in the blind, eye, and split areas within a cheese block. The variability of VOC profiles within and between factories exhibit varied biochemical fermentation pathways that could conceivably be traced back in the making process to identify parameters responsible for split defect. © 2014 Institute of Food Technologists®

Myocardial perfusion imaging with thallium-201: correlation with coronary arteriography and electrocardiography

PubMed Central

Sternberg, Leonard; Wald, Robert W.; Feiglin, David H.I.; Morch, John E.

1978-01-01

Myocardial perfusion imaging with thallium-201 and electrocardiography with the subject at rest and undergoing submaximal treadmill exercise were performed in 19 men and 3 women. Selective coronary arteriography and left ventriculography showed that 7 had normal coronary arteries and 15 had coronary artery disease. The 11 persons with electrocardiographic evidence of an old myocardial infarct (q waves) had a perfusion defect at rest in the area of the infarct and a segmental abnormality of wall motion apparent on the left ventriculogram corresponding to the perfusion defect. Myocardial perfusion imaging and electrocardiography were equally sensitive in detecting coronary artery disease in exercising individuals: perfusion defects were noted in 7 of the 15 persons with coronary artery disease, and diagnostic ST-segment depression was present in 8 of the 15. Combination of the results of the two tests with exercise permitted the identification of 11 of the 15 persons and improved the sensitivity. Combination of the results of rest and exercise imaging and electrocardiography permitted the identification of 94% of the patients with coronary artery disease. Myocardial perfusion imaging with 201TI in the subject at rest is a sensitive indicator of previous myocardial infarction. Imaging after the subject has exercised is a useful adjunct to conventional exercise electrocardiography, especially in those whose exercise electrocardiogram is non-interpretable. ImagesFIG. 1FIG. 2FIG. 3FIG. 4FIG. 5 PMID:630487

In vitro and in vivo study of additive manufactured porous Ti6Al4V scaffolds for repairing bone defects

NASA Astrophysics Data System (ADS)

Li, Guoyuan; Wang, Lei; Pan, Wei; Yang, Fei; Jiang, Wenbo; Wu, Xianbo; Kong, Xiangdong; Dai, Kerong; Hao, Yongqiang

2016-09-01

Metallic implants with a low effective modulus can provide early load-bearing and reduce stress shielding, which is favorable for increasing in vivo life-span. In this research, porous Ti6Al4V scaffolds with three pore sizes (300~400, 400~500, and 500~700 μm) were manufactured by Electron Beam Melting, with an elastic modulus range of 3.7 to 1.7 GPa. Cytocompatibility in vitro and osseointegration ability in vivo of scaffolds were assessed. hBMSCs numbers increased on all porous scaffolds over time. The group with intended pore sizes of 300 to 400 μm was significantly higher than that of the other two porous scaffolds at days 5 and 7. This group also had higher ALP activity at day 7 in osteogenic differentiation experiment. The scaffold with pore size of 300 to 400 μm was implanted into a 30-mm segmental defect of goat metatarsus. In vivo evaluations indicated that the depth of bone ingrowth increased over time and no implant dislocation occurred during the experiment. Based on its better cytocompatibility and favorable bone ingrowth, the present data showed the capability of the additive manufactured porous Ti6Al4V scaffold with an intended pore size of 300 to 400 μm for large segmental bone defects.

Simultaneous macula detection and optic disc boundary segmentation in retinal fundus images

NASA Astrophysics Data System (ADS)

Girard, Fantin; Kavalec, Conrad; Grenier, Sébastien; Ben Tahar, Houssem; Cheriet, Farida

2016-03-01

The optic disc (OD) and the macula are important structures in automatic diagnosis of most retinal diseases inducing vision defects such as glaucoma, diabetic or hypertensive retinopathy and age-related macular degeneration. We propose a new method to detect simultaneously the macula and the OD boundary. First, the color fundus images are processed to compute several maps highlighting the different anatomical structures such as vessels, the macula and the OD. Then, macula candidates and OD candidates are found simultaneously and independently using seed detectors identified on the corresponding maps. After selecting a set of macula/OD pairs, the top candidates are sent to the OD segmentation method. The segmentation method is based on local K-means applied to color coordinates in polar space followed by a polynomial fitting regularization step. Pair scores are updated, resulting in the final best macula/OD pair. The method was evaluated on two public image databases: ONHSD and MESSIDOR. The results show an overlapping area of 0.84 on ONHSD and 0.90 on MESSIDOR, which is better than recent state of the art methods. Our segmentation method is robust to contrast and illumination problems and outputs the exact boundary of the OD, not just a circular or elliptical model. The macula detection has an accuracy of 94%, which again outperforms other macula detection methods. This shows that combining the OD and macula detections improves the overall accuracy. The computation time for the whole process is 6.4 seconds, which is faster than other methods in the literature.

Toward Patient Specific Long Lasting Metallic Implants for Mandibular Segmental Defects

NASA Astrophysics Data System (ADS)

Shayesteh Moghaddam, Narges

Mandibular defects may result from tumor resection, trauma, or inflammation. The goals of mandibular reconstruction surgeries are to restore mandible function and aesthetics. To this end, surgeons use a combination of bone grafts and metallic implants. These implants have drastically different mechanical properties than the surrounding bone. As a result, the stress distribution in the mandible changes after surgery. The long-term abnormal stress/strain distribution may lead to either graft failure due to bone resorption as a result of stress shielding, or hardware failure due to stress concentrations. During the healing period of six to nine months it is important that complete immobilization, bringing mandibular micro-motion down to the level of 200-500 mum during chewing, is achieved. After this period it is desired that bone undergo normal stress for long-term success of the treatment. Although current high stiffness fixation hardware accomplishes this immobilization during the healing period, the hardware continues to alter the normal stress-strain trajectory seen during chewing once the engrafted bone heals. Over the long-term, the immobilized and stress-shielded engrafted bone tends to resorb. On the other hand, hardware fracturing or/and screw loosening is observed as the stress is concentrated at certain locations on the hardware. Equally as important is the permanent loss of chewing power due to the altered stress-strain relationships. The first stage of this research is to study the problems encountered following a mandibular segmental defect reconstructive surgery. To this end, we constructed a finite element model of a healthy mandible, which includes cortical and cancellous bone, teeth (enamel and dentin components), and the periodontal ligament. Using this model, we studied a healthy adult mandible under maximum molar bite force for stress, strain, displacement, and reaction force distribution. For mandibular segmental defect reconstruction the current standard of care consists of the use of Surgical Grade 5 titanium also known as Ti-6Al-4V hardware and either a single or double fibula barrel vascularized bone graft. We expanded our model to simulate the effects of this surgery. The expanded model includes both single and double barrel fibular bone graft repair of a right M1-M3 containing section of the mandible, Ti-6Al-4V fixation hardware and screws. We found that the stiffness mismatch between the fixation hardware and the bone causes stress shielding on the host mandible and the bone graft, and stress concentration at the fixation hardware and screws. The simulations results show that while a double-barrel graft is preferred, in the long-term it does not create the optimal outcome due to the abnormal stress pattern. To improve the long-term outcome with metallic implants it is essential to recreate the normal stress pattern. To achieve this outcome we investigated the use of porous nitinol as a substitute for the currently used titanium hardware. While NiTi already has a lower stiffness than titanium, it is possible to add porosity to further reduce the stiffness to be closer to that of cortical bone. The ultimate goal is to create fixation hardware that has sufficient stiffness for immobilization while recreating the normal stress pattern in the bone. Using a finite element model of devices fabricated from Surgical Grade 5 titanium and NiTi, we have found that stiffness-tuned NiTi hardware with conventional geometries should result in recreation of normal stress-strain trajectories and better treatment outcome. Finally, to further improve the outcome, we suggest the use of a two-stage mechanism Bone Bandaid which supports both the immobilization/healing and regenerative phases of mandibular segmental defect treatment. This device is made of two materials. The stiff Ti-6Al-4V portion provides the support during the healing period and is disengaged afterwards. The second material is a NiTi wire-frame to facilitate normal stress distribution after the initial healing period. The titanium part of this fixation hardware is released following radiological verification that the surgical osteotomies have healed. The release procedure is performed under local anesthetic via a microsurgical tool. With the titanium fixation hardware no longer functional, the NiTi webbing would act as a superstructure, like a skin, to the underlying grafted cortical bone. This device facilitates stress transduction through the normal stress-strain trajectories, allows restoration of power, drives cortical bone remodeling and strengthening, provides long-term strength, and a good bone bed for dental implants. If bone chips are used, instead of single or double bone graft, the webbing is more likely to support the bone chips while they are being incorporated with the mandible. We have performed computer simulation to investigate the two stages of the operation of the device. Our FEA results indicate that the Bone Bandaid supports both the immobilization needed during healing and the distribution of stress through the engrafted bone once it has healed. (Abstract shortened by ProQuest.).

Comparison of Post-Processing Techniques for the Detection of Perfusion Defects by Cardiac Computed Tomography in Patients Presenting with Acute ST Segment Elevation Myocardial Infarction

PubMed Central

Rogers, Ian S.; Cury, Ricardo C.; Blankstein, Ron; Shapiro, Michael D.; Nieman, Koen; Hoffmann, Udo; Brady, Thomas J.; Abbara, Suhny

2010-01-01

Background Despite rapid advances in cardiac computed tomography (CT), a strategy for optimal visualization of perfusion abnormalities on CT has yet to be validated. Objective To evaluate the performance of several post-processing techniques of source data sets to detect and characterize perfusion defects in acute myocardial infarctions with cardiac CT. Methods Twenty-one subjects (18 men; 60 ± 13 years) that were successfully treated with percutaneous coronary intervention for ST-segment myocardial infarction underwent 64-slice cardiac CT and 1.5 Tesla cardiac MRI scans following revascularization. Delayed enhancement MRI images were analyzed to identify the location of infarcted myocardium. Contiguous short axis images of the left ventricular myocardium were created from the CT source images using 0.75mm multiplanar reconstruction (MPR), 5mm MPR, 5mm maximal intensity projection (MIP), and 5mm minimum intensity projection (MinIP) techniques. Segments already confirmed to contain infarction by MRI were then evaluated qualitatively and quantitatively with CT. Results Overall, 143 myocardial segments were analyzed. On qualitative analysis, the MinIP and thick MPR techniques had greater visibility and definition than the thin MPR and MIP techniques (p < 0.001). On quantitative analysis, the absolute difference in Hounsfield Unit (HU) attenuation between normal and infarcted segments was significantly greater for the MinIP (65.4 HU) and thin MPR (61.2 HU) techniques. However, the relative difference in HU attenuation was significantly greatest for the MinIP technique alone (95%, p < 0.001). Contrast to noise was greatest for the MinIP (4.2) and thick MPR (4.1) techniques (p < 0.001). Conclusion The results of our current investigation found that MinIP and thick MPR detected infarcted myocardium with greater visibility and definition than MIP and thin MPR. PMID:20579617

Stratigraphic Architecture of Aeolian Dune Interactions

NASA Astrophysics Data System (ADS)

Brothers, S. C.; Kocurek, G.

2015-12-01

Dune interactions, which consist of collisions and detachments, are a known driver of changing dune morphology and provide the dynamics for field-scale patterning. Although interactions are ubiquitous in modern dune fields, the stratigraphic record of interactions has not been explored. This raises the possibility that an entire class of signature architectures of bounding surfaces and cross-strata has gone misidentified or unrecognized. A unique data set for the crescentic dunes of the White Sands Dune Field, New Mexico, allows for the coupling of dune interactions with their resultant stratigraphic architecture. Dune interactions are documented by a decadal time-series of aerial photos and LiDAR-derived digital elevation models. Plan-view cross-strata in interdune areas provide a record tying past dune positions and morphologies to the current dunes. Three-dimensional stratigraphic architecture is revealed by imaging of dune interiors with ground-penetrating radar. The architecture of a dune defect merging with a target dune downwind consists of lateral truncation of the target dune set by an interaction bounding surface. Defect cross-strata tangentially approach and downlap onto the surface. Downwind, the interaction surface curves, and defect and adjacent target dune sets merge into a continuous set. Predictable angular relationships reflect field-scale patterns of dune migration direction and approach angle of migrating defects. The discovery of interaction architectures emphasizes that although dunes appear as continuous forms on the surface, they consist of discrete segments, each with a distinct morphodynamic history. Bedform interactions result in the morphologic recombination of dune bodies, which is manifested stratigraphically within the sets of cross-strata.

3D characterization of EMT cell density in developing cardiac cushions using optical coherence tomography (Conference Presentation)

NASA Astrophysics Data System (ADS)

Yu, Siyao; Gu, Shi; Zhao, Xiaowei; Liu, Yehe; Jenkins, Michael W.; Watanabe, Michiko; Rollins, Andrew M.

2017-02-01

Congenital heart defects (CHDs) are the most common birth defect, affecting between 4 and 75 per 1,000 live births depending on the inclusion criteria. Many of these defects can be traced to defects of cardiac cushions, critical structures during development that serve as precursors to many structures in the mature heart, including the atrial and ventricular septa, and all four sets of cardiac valves. Epithelial-mesenchymal transition (EMT) is the process through which cardiac cushions become populated with cells. Altered cushion size or altered cushion cell density has been linked to many forms of CHDs, however, quantitation of cell density in the complex 3D cushion structure poses a significant challenge to conventional histology. Optical coherence tomography (OCT) is a technique capable of 3D imaging of the developing heart, but typically lacks the resolution to differentiate individual cells. Our goal is to develop an algorithm to quantitatively characterize the density of cells in the developing cushion using 3D OCT imaging. First, in a heart volume, the atrioventricular (AV) cushions were manually segmented. Next, all voxel values in the region of interest were pooled together to generate a histogram. Finally, two populations of voxels were classified using either K-means classification, or a Gaussian mixture model (GMM). The voxel population with higher values represents cells in the cushion. To test the algorithm, we imaged and evaluated avian embryonic hearts at looping stages. As expected, our result suggested that the cell density increases with developmental stages. We validated the technique against scoring by expert readers.

Ex vivo method to visualize and quantify vascular networks in native and tissue engineered skin.

PubMed

Egaña, José Tomás; Condurache, Alexandru; Lohmeyer, Jörn Andreas; Kremer, Mathias; Stöckelhuber, Beate M; Lavandero, Sergio; Machens, Hans-Günther

2009-03-01

Neovascularization plays a pivotal role in tissue engineering and tissue regeneration. However, reliable technologies to visualize and quantify blood vessel networks in target tissue areas are still pending. In this work, we introduce a new method which allows comparing vascularization levels in normal and tissue-engineered skin. Normal skin was isolated, and vascular dermal regeneration was analyzed based on tissue transillumination and computerized digital segmentation. For tissue-engineered skin, a bilateral full skin defect was created in a nude mouse model and then covered with a commercially available scaffold for dermal regeneration. After 3 weeks, the whole skin (including scaffold for dermal regeneration) was harvested, and vascularization levels were analyzed. The blood vessel network in the skin was better visualized by transillumination than by radio-angiographic studies, the gold standard for angiographies. After visualization, the whole vascular network was digitally segmented showing an excellent overlapping with the original pictures. Quantification over the digitally segmented picture was performed, and an index of vascularization area (VAI) and length (VLI) of the vessel network was obtained in target tissues. VAI/VLI ratio was calculated to obtain the vessel size index. We present a new technique which has several advantages compared to others, as animals do not require intravascular perfusions, total areas of interest can be quantitatively analyzed at once, and the same target tissue can be processed for further experimental analysis.

Quality inspection guided laser processing of irregular shape objects by stereo vision measurement: application in badminton shuttle manufacturing

NASA Astrophysics Data System (ADS)

Qi, Li; Wang, Shun; Zhang, Yixin; Sun, Yingying; Zhang, Xuping

2015-11-01

The quality inspection process is usually carried out after first processing of the raw materials such as cutting and milling. This is because the parts of the materials to be used are unidentified until they have been trimmed. If the quality of the material is assessed before the laser process, then the energy and efforts wasted on defected materials can be saved. We proposed a new production scheme that can achieve quantitative quality inspection prior to primitive laser cutting by means of three-dimensional (3-D) vision measurement. First, the 3-D model of the object is reconstructed by the stereo cameras, from which the spatial cutting path is derived. Second, collaborating with another rear camera, the 3-D cutting path is reprojected to both the frontal and rear views of the object and thus generates the regions-of-interest (ROIs) for surface defect analysis. An accurate visual guided laser process and reprojection-based ROI segmentation are enabled by a global-optimization-based trinocular calibration method. The prototype system was built and tested with the processing of raw duck feathers for high-quality badminton shuttle manufacture. Incorporating with a two-dimensional wavelet-decomposition-based defect analysis algorithm, both the geometrical and appearance features of the raw feathers are quantified before they are cut into small patches, which result in fully automatic feather cutting and sorting.

Automatic moment segmentation and peak detection analysis of heart sound pattern via short-time modified Hilbert transform.

PubMed

Sun, Shuping; Jiang, Zhongwei; Wang, Haibin; Fang, Yu

2014-05-01

This paper proposes a novel automatic method for the moment segmentation and peak detection analysis of heart sound (HS) pattern, with special attention to the characteristics of the envelopes of HS and considering the properties of the Hilbert transform (HT). The moment segmentation and peak location are accomplished in two steps. First, by applying the Viola integral waveform method in the time domain, the envelope (E(T)) of the HS signal is obtained with an emphasis on the first heart sound (S1) and the second heart sound (S2). Then, based on the characteristics of the E(T) and the properties of the HT of the convex and concave functions, a novel method, the short-time modified Hilbert transform (STMHT), is proposed to automatically locate the moment segmentation and peak points for the HS by the zero crossing points of the STMHT. A fast algorithm for calculating the STMHT of E(T) can be expressed by multiplying the E(T) by an equivalent window (W(E)). According to the range of heart beats and based on the numerical experiments and the important parameters of the STMHT, a moving window width of N=1s is validated for locating the moment segmentation and peak points for HS. The proposed moment segmentation and peak location procedure method is validated by sounds from Michigan HS database and sounds from clinical heart diseases, such as a ventricular septal defect (VSD), an aortic septal defect (ASD), Tetralogy of Fallot (TOF), rheumatic heart disease (RHD), and so on. As a result, for the sounds where S2 can be separated from S1, the average accuracies achieved for the peak of S1 (AP₁), the peak of S2 (AP₂), the moment segmentation points from S1 to S2 (AT₁₂) and the cardiac cycle (ACC) are 98.53%, 98.31% and 98.36% and 97.37%, respectively. For the sounds where S1 cannot be separated from S2, the average accuracies achieved for the peak of S1 and S2 (AP₁₂) and the cardiac cycle ACC are 100% and 96.69%. Copyright © 2014 Elsevier Ireland Ltd. All rights reserved.

Correlation between postoperative area of high autofluorescence in macula and visual acuity after macular hole closure.

PubMed

Zhang, Peng; Shang, Qingli; Ma, Jingxue; Hao, Yuhua; Ye, Cunxi

2017-03-20

To determine the correlation between the preoperative basal diameter of macular hole, the postoperative area of high autofluorescence (AF) in macula, and visual acuity in full-thickness macular hole. Forty-nine patients with full-thickness macular hole who underwent vitrectomy and C3F8 filling were reviewed. The preoperative diameter of macular hole, the 6 months postoperative area of high AF in macula if it existed, the length of inner segment/outer segment (IS/OS) defect, and visual acuity were obtained. The correlation between them was determined. At postoperative 6 months, the rate of high AF in macula was 63.3%. There were statistical differences between with and without high AF groups in postoperative best-corrected visual acuity (BCVA) (t = -2.751, p = 0.008), preoperative basal diameter of macular hole (t = -4.946, p = 0.00001), and postoperative length of IS/OS defect (t = -8.351, p<0.00001). Simple linear regression analysis showed high positive correlations between preoperative basal diameter of macular hole and area of high AF (p<0.00001, r = 0.893), postoperative length of IS/OS defect and area of high fundus AF (FAF) (p<0.00001, r = 0.779), and negative correlations between area of high AF and postoperative BCVA (p = 0.037, r = 0.375). There was low correlation between diameter of macular hole and postoperative BCVA (p = 0.112). The preoperative basal diameter of macular hole and postoperative length of IS/OS defect decides the postoperative area of high AF in macula to some degree, and the postoperative area of high AF in macula can be an evaluating indicator for poor macular function recovery.

Influence of the overall stiffness of a load-bearing porous titanium implant on bone ingrowth in critical-size mandibular bone defects in sheep.

PubMed

Schouman, T; Schmitt, M; Adam, C; Dubois, G; Rouch, P

2016-06-01

The aim of this work was to assess the influence of reduction of the apparent mechanical properties of fully load-bearing porous titanium implants used in mandibular bone defects. Segmental 18mm long bone defects were created bilaterally in the lower jaws of adult ewes. One group of 6 ewes (group A) was treated with load-bearing 'rigid' (high stiffness) porous implants on the right side, and with control on the left side. A second group of 6 ewes (group B) was treated with 'flexible' porous and control implants exhibiting apparent mechanical properties ten times lower than the rigid implants. The mechanical behavior of the reconstructed hemi-mandibles was assessed by cantilever testing and bone ingrowth into the segmental defects was assessed by BV/TV measurement within the implant using micro-CT 12 weeks after implantation. A significantly higher rigidity was identified for porous implants compared with control implants at the anterior interface in group B. BV/TV of porous implants was significantly higher than that of control implants in group A. BV/TV differences were significant between porous and control implants in group B and were homogeneous along the main axis. Significantly higher BV/TV was identified in most sub-volumes of group B porous implants compared with group A. This work highlights the critical importance of the tuning of scaffolds to promote bone ingrowth with reference to the local strains occurring within the porous scaffold, which in this application was achieved using fully load-bearing low-stiffness porous titanium implants. Copyright © 2016 Elsevier Ltd. All rights reserved.

Length of nerve gap defects correlates with incidence of nerve regeneration but not with recovery of taste function in patients with severed chorda tympani nerve.

PubMed

Saito, Takehisa; Narita, Norihiko; Yamada, Takechiyo; Ogi, Kazuhiro; Kanno, Masafumi; Manabe, Yasuhiro; Ito, Tetsufumi

2011-10-01

To evaluate the relationship between the length of nerve gap defects, incidence of nerve regeneration, and recovery of gustatory function after severing the chorda tympani nerve (CTN). Retrospective study. University hospital. Eighty-eight consecutive patients whose CTNs were severed during primary surgery and who underwent secondary surgery were included. Proximal and distal stumps of severed nerves were readapted or approximated during surgery. Therapeutic. Before and after surgery, the taste function was periodically evaluated using electrogustometry. Nerve gaps were classified into 4 groups: readaptation (Group 1), 1 to 3 mm (Group 2), 4 to 6 mm (Group 3), and more than 7 mm (Group 4). Regenerated nerves in the tympanic segment were detected in 36 (41%) of the 88 patients during secondary surgery. The incidence of nerve regeneration was 100% (10/10) in Group 1, 45% (10/22) in Group 2, 47% (9/19) in Group 3, and 19% (7/37) in Group 4. There was a significant difference between the length of nerve gap defects and incidence of nerve regeneration (p < 0.001). In the 36 patients with a regenerated CTN, the incidence of gustatory function recovery was 60% (6/10) in Group 1, 50% (5/10) in Group 2, 56% (5/9) in Group 3, and 43% (3/7) in Group 4. There was no significant difference between the length of nerve gap defects and incidence of taste function recovery. Reconstruction of a severed CTN is very important for regeneration. However, the regenerated CTN in the tympanic segment does not always reinnervate the fungiform papillae.

7 CFR 51.1837 - Classification of defects.

Code of Federal Regulations, 2012 CFR

2012-01-01

... STANDARDS) United States Standards for Grades of Florida Tangerines Definitions § 51.1837 Classification of...) at stem end, or the equivalent of this amount, by volume, when occurring in other portions of the fruit Affecting all segments more than 1/4 inch (6.4 mm) at stem end, or the equivalent of this amount...

7 CFR 51.784 - Classification of defects.

Code of Federal Regulations, 2012 CFR

2012-01-01

... STANDARDS) United States Standards for Grades of Florida Grapefruit Definitions § 51.784 Classification of.... Dryness or mushy condition Affecting all segments more than 1/4 inch (6.4 mm) at stem end, or the... more than 1/2 inch (12.7 mm) at stem end, or the equivalent of this amount, by volume, when occurring...

7 CFR 51.1837 - Classification of defects.

Code of Federal Regulations, 2011 CFR

2011-01-01

... STANDARDS) United States Standards for Grades of Florida Tangerines Definitions § 51.1837 Classification of...) at stem end, or the equivalent of this amount, by volume, when occurring in other portions of the fruit Affecting all segments more than 1/4 inch (6.4 mm) at stem end, or the equivalent of this amount...

Histogram-based automatic thresholding for bruise detection of apples by structured-illumination reflectance imaging

USDA-ARS?s Scientific Manuscript database

Thresholding is an important step in the segmentation of image features, and the existing methods are not all effective when the image histogram exhibits a unimodal pattern, which is common in defect detection of fruit. This study was aimed at developing a general automatic thresholding methodology ...

An intelligent system for real time automatic defect inspection on specular coated surfaces

NASA Astrophysics Data System (ADS)

Li, Jinhua; Parker, Johné M.; Hou, Zhen

2005-07-01

Product visual inspection is still performed manually or semi automatically in most industries from simple ceramic tile grading to complex automotive body panel paint defect and surface quality inspection. Moreover, specular surfaces present additional challenge to conventional vision systems due to specular reflections, which may mask the true location of objects and lead to incorrect measurements. There are some sophisticated visual inspection methods developed in recent years. Unfortunately, most of them are highly computational. Systems built on those methods are either inapplicable or very costly to achieve real time inspection. In this paper, we describe an integrated low-cost intelligent system developed to automatically capture, extract, and segment defects on specular surfaces with uniform color coatings. The system inspects and locates regular surface defects with lateral dimensions as small as a millimeter. The proposed system is implemented on a group of smart cameras using its on-board processing ability to achieve real time inspection. The experimental results on real test panels demonstrate the effectiveness and robustness of proposed system.

[Clinical significance of myocardial 123I-BMIPP imaging in patients with myocardial infarction].

PubMed

Narita, M; Kurihara, T; Shindoh, T; Honda, M

1997-03-01

In order to clarify the characteristics of fatty acid metabolism in patients with myocardial infarction (MI), we performed myocardial imaging with 123I-beta-methyl-p-iodophenylpentadecanoic acid (BMIPP) and we compared these findings with exercise stress (Ex) and resting myocardial perfusion imaging with 99mTc-methoxyisobutylisonitrile (MIBI) and left ventricular wall motion index (WMI) which were obtained by left ventriculography. We studied 55 patients with MI, 14 patients with recent MI (RMI) and 41 patients with old MI (OMI), and myocardial images were divided into 17 segments and myocardial uptake of the radionuclide was graded from 0 (normal) to 3 (maximal abnormality). In 28 patients we compared segmental defect score (SDS) with WMI which were obtained by centerline method at the corresponded segments. As a whole, the mean total defect scores (TDSs) of BMIPP and Ex were similar and they were greater than the mean TDS of resting perfusion. In 30 patient (55%) TDS of BMIPP was greater than that of TDS of resting perfusion. In 24 patients perfusion abnormality developed by Ex and the location of BMIPP abnormality coincided with the abnormality of Ex. But in the other 6 patients Ex did not induce any abnormality and they were all RMI and infarcted coronary artery was patent. However in the group with TDS of BMIPP identical to TDS of resting perfusion (25 patients), 92% did not show myocardial perfusion abnormality after Ex. In the comparison of SDS and WMI, myocardial segments were divided into 3 groups; both SDSs of BMIPP and resting perfusion were normal or borderline abnormality (Group 1, 82 segments), SDS of resting perfusion was normal or borderline and SDS of BMIPP was definitely abnormal (Group 2, 10 segments) and both SDSs of BMIPP and resting perfusion were definitely abnormal (Group 3, 48 segments). In Group 1, WMS (-0.41 +/- 0.77) was significantly (p < 0.001) greater than those of Group 2 (-2.14 +/- 0.50) and Group 3 (-2.32 +/- 0.67). But there was no difference between Group 2 and 3. These findings suggested that in the segments with mismatch between BMIPP and resting perfusion reflects stunned myocardium. These results suggested that in half of the patients with MI, abnormal fatty acid metabolism may appear in viable myocardium such as jeopardized myocardium and myocardium which recently recovered from severe ischemia like acute MI and BMIPP imaging was useful to know the history of myocardial ischemia.

Photoluminescence Segmentation within Individual Hexagonal Monolayer Tungsten Disulfide Domains Grown by Chemical Vapor Deposition.

PubMed

Sheng, Yuewen; Wang, Xiaochen; Fujisawa, Kazunori; Ying, Siqi; Elias, Ana Laura; Lin, Zhong; Xu, Wenshuo; Zhou, Yingqiu; Korsunsky, Alexander M; Bhaskaran, Harish; Terrones, Mauricio; Warner, Jamie H

2017-05-03

We show that hexagonal domains of monolayer tungsten disulfide (WS 2 ) grown by chemical vapor deposition (CVD) with powder precursors can have discrete segmentation in their photoluminescence (PL) emission intensity, forming symmetric patterns with alternating bright and dark regions. Two-dimensional maps of the PL reveal significant reduction within the segments associated with the longest sides of the hexagonal domains. Analysis of the PL spectra shows differences in the exciton to trion ratio, indicating variations in the exciton recombination dynamics. Monolayers of WS 2 hexagonal islands transferred to new substrates still exhibit this PL segmentation, ruling out local strain in the regions as the dominant cause. High-power laser irradiation causes preferential degradation of the bright segments by sulfur removal, indicating the presence of a more defective region that is higher in oxidative reactivity. Atomic force microscopy (AFM) images of topography and amplitude modes show uniform thickness of the WS 2 domains and no signs of segmentation. However, AFM phase maps do show the same segmentation of the domain as the PL maps and indicate that it is caused by some kind of structural difference that we could not clearly identify. These results provide important insights into the spatially varying properties of these CVD-grown transition metal dichalcogenide materials, which may be important for their effective implementation in fast photo sensors and optical switches.

Integrating image processing and classification technology into automated polarizing film defect inspection

NASA Astrophysics Data System (ADS)

Kuo, Chung-Feng Jeffrey; Lai, Chun-Yu; Kao, Chih-Hsiang; Chiu, Chin-Hsun

2018-05-01

In order to improve the current manual inspection and classification process for polarizing film on production lines, this study proposes a high precision automated inspection and classification system for polarizing film, which is used for recognition and classification of four common defects: dent, foreign material, bright spot, and scratch. First, the median filter is used to remove the impulse noise in the defect image of polarizing film. The random noise in the background is smoothed by the improved anisotropic diffusion, while the edge detail of the defect region is sharpened. Next, the defect image is transformed by Fourier transform to the frequency domain, combined with a Butterworth high pass filter to sharpen the edge detail of the defect region, and brought back by inverse Fourier transform to the spatial domain to complete the image enhancement process. For image segmentation, the edge of the defect region is found by Canny edge detector, and then the complete defect region is obtained by two-stage morphology processing. For defect classification, the feature values, including maximum gray level, eccentricity, the contrast, and homogeneity of gray level co-occurrence matrix (GLCM) extracted from the images, are used as the input of the radial basis function neural network (RBFNN) and back-propagation neural network (BPNN) classifier, 96 defect images are then used as training samples, and 84 defect images are used as testing samples to validate the classification effect. The result shows that the classification accuracy by using RBFNN is 98.9%. Thus, our proposed system can be used by manufacturing companies for a higher yield rate and lower cost. The processing time of one single image is 2.57 seconds, thus meeting the practical application requirement of an industrial production line.

[Repairing of soft tissue defect in leg by free vascularized thoracoumbilical flap with reversed flow].

PubMed

Xu, Y Q; Li, Z Y; Li, J

2000-11-01

To investigate the clinical effect of free vascularized thoracoumbilical flap with reversal flow in repairing the soft tissue defect in leg with tibia exposure. Forty-four casting mould specimens of leg arteries were studied firstly. Then 25 cases with soft tissue defect and tibia exposure in the proximal-middle segment of leg were adopted in this study. Among them, 18 cases had long distance thrombosis of the anterior tibial vessels or posterior tibial vessels due to traumatic lesion. The maximal size of defect was 28 cm x 11 cm and the minimal size of defect was 11 cm x 9 cm. In operation, the thoracoumbilical flap which was based on the inferior epigastric vessels was anastomosed to the distal end of the anterior tibial vessels or posterior tibial vessels. Anterior tibial artery, posterior tibial artery and fibular artery had rich communication branches in foot and ankle. All the flaps survived, the color and cosmetic result of them were good. The free vascularized thoracoumbilical flap with reversed flow is practical in repairing the soft tissue defect of leg with tibia exposure. Either the anterior tibial vessels or the posterior tibial vessels is normal, and the distal end of injured blood vessels is available, this technique can be adopted.

Finite-element design and optimization of a three-dimensional tetrahedral porous titanium scaffold for the reconstruction of mandibular defects.

PubMed

Luo, Danmei; Rong, Qiguo; Chen, Quan

2017-09-01

Reconstruction of segmental defects in the mandible remains a challenge for maxillofacial surgery. The use of porous scaffolds is a potential method for repairing these defects. Now, additive manufacturing techniques provide a solution for the fabrication of porous scaffolds with specific geometrical shapes and complex structures. The goal of this study was to design and optimize a three-dimensional tetrahedral titanium scaffold for the reconstruction of mandibular defects. With a fixed strut diameter of 0.45mm and a mean cell size of 2.2mm, a tetrahedral structural porous scaffold was designed for a simulated anatomical defect derived from computed tomography (CT) data of a human mandible. An optimization method based on the concept of uniform stress was performed on the initial scaffold to realize a minimal-weight design. Geometric and mechanical comparisons between the initial and optimized scaffold show that the optimized scaffold exhibits a larger porosity, 81.90%, as well as a more homogeneous stress distribution. These results demonstrate that tetrahedral structural titanium scaffolds are feasible structures for repairing mandibular defects, and that the proposed optimization scheme has the ability to produce superior scaffolds for mandibular reconstruction with better stability, higher porosity, and less weight. Copyright © 2017 IPEM. Published by Elsevier Ltd. All rights reserved.

Exploring combined dark and bright field illumination to improve the detection of defects on specular surfaces

NASA Astrophysics Data System (ADS)

Forte, Paulo M. F.; Felgueiras, P. E. R.; Ferreira, Flávio P.; Sousa, M. A.; Nunes-Pereira, Eduardo J.; Bret, Boris P. J.; Belsley, Michael S.

2017-01-01

An automatic optical inspection system for detecting local defects on specular surfaces is presented. The system uses an image display to produce a sequence of structured diffuse illumination patterns and a digital camera to acquire the corresponding sequence of images. An image enhancement algorithm, which measures the local intensity variations between bright- and dark-field illumination conditions, yields a final image in which the defects are revealed with a high contrast. Subsequently, an image segmentation algorithm, which compares statistically the enhanced image of the inspected surface with the corresponding image for a defect-free template, allows separating defects from non-defects with an adjusting decision threshold. The method can be applied to shiny surfaces of any material including metal, plastic and glass. The described method was tested on the plastic surface of a car dashboard system. We were able to detect not only scratches but also dust and fingerprints. In our experiment we observed a detection contrast increase from about 40%, when using an extended light source, to more than 90% when using a structured light source. The presented method is simple, robust and can be carried out with short cycle times, making it appropriate for applications in industrial environments.

NRC/AMRMC Resident Research Associateship Program

DTIC Science & Technology

2015-03-01

antimicrobials (and antiseptics) as well as to evaluate the effectiveness of various biofilm dispersal agents utilizing a number of bacterial species as...combat related wounds. 3 Demonstrated the utility of combinations of biofilm dispersal agents and antimicrobials as an alternate therapy for...alone or in combination with antimicrobials ) to reduce infection in contaminated femoral segmental defects. 5 Characterized host responses of

Loss of ift122, a Retrograde Intraflagellar Transport (IFT) Complex Component, Leads to Slow, Progressive Photoreceptor Degeneration Due to Inefficient Opsin Transport.

PubMed

Boubakri, Meriam; Chaya, Taro; Hirata, Hiromi; Kajimura, Naoko; Kuwahara, Ryusuke; Ueno, Akiko; Malicki, Jarema; Furukawa, Takahisa; Omori, Yoshihiro

2016-11-18

In the retina, aberrant opsin transport from cell bodies to outer segments leads to retinal degenerative diseases such as retinitis pigmentosa. Opsin transport is facilitated by the intraflagellar transport (IFT) system that mediates the bidirectional movement of proteins within cilia. In contrast to functions of the anterograde transport executed by IFT complex B (IFT-B), the precise functions of the retrograde transport mediated by IFT complex A (IFT-A) have not been well studied in photoreceptor cilia. Here, we analyzed developing zebrafish larvae carrying a null mutation in ift122 encoding a component of IFT-A. ift122 mutant larvae show unexpectedly mild phenotypes, compared with those of mutants defective in IFT-B. ift122 mutants exhibit a slow onset of progressive photoreceptor degeneration mainly after 7 days post-fertilization. ift122 mutant larvae also develop cystic kidney but not curly body, both of which are typically observed in various ciliary mutants. ift122 mutants display a loss of cilia in the inner ear hair cells and nasal pit epithelia. Loss of ift122 causes disorganization of outer segment discs. Ectopic accumulation of an IFT-B component, ift88, is observed in the ift122 mutant photoreceptor cilia. In addition, pulse-chase experiments using GFP-opsin fusion proteins revealed that ift122 is required for the efficient transport of opsin and the distal elongation of outer segments. These results show that IFT-A is essential for the efficient transport of outer segment proteins, including opsin, and for the survival of retinal photoreceptor cells, rendering the ift122 mutant a unique model for human retinal degenerative diseases. © 2016 by The American Society for Biochemistry and Molecular Biology, Inc.

Loss of ift122, a Retrograde Intraflagellar Transport (IFT) Complex Component, Leads to Slow, Progressive Photoreceptor Degeneration Due to Inefficient Opsin Transport*

PubMed Central

Boubakri, Meriam; Chaya, Taro; Hirata, Hiromi; Kajimura, Naoko; Kuwahara, Ryusuke; Ueno, Akiko; Malicki, Jarema; Furukawa, Takahisa; Omori, Yoshihiro

2016-01-01

In the retina, aberrant opsin transport from cell bodies to outer segments leads to retinal degenerative diseases such as retinitis pigmentosa. Opsin transport is facilitated by the intraflagellar transport (IFT) system that mediates the bidirectional movement of proteins within cilia. In contrast to functions of the anterograde transport executed by IFT complex B (IFT-B), the precise functions of the retrograde transport mediated by IFT complex A (IFT-A) have not been well studied in photoreceptor cilia. Here, we analyzed developing zebrafish larvae carrying a null mutation in ift122 encoding a component of IFT-A. ift122 mutant larvae show unexpectedly mild phenotypes, compared with those of mutants defective in IFT-B. ift122 mutants exhibit a slow onset of progressive photoreceptor degeneration mainly after 7 days post-fertilization. ift122 mutant larvae also develop cystic kidney but not curly body, both of which are typically observed in various ciliary mutants. ift122 mutants display a loss of cilia in the inner ear hair cells and nasal pit epithelia. Loss of ift122 causes disorganization of outer segment discs. Ectopic accumulation of an IFT-B component, ift88, is observed in the ift122 mutant photoreceptor cilia. In addition, pulse-chase experiments using GFP-opsin fusion proteins revealed that ift122 is required for the efficient transport of opsin and the distal elongation of outer segments. These results show that IFT-A is essential for the efficient transport of outer segment proteins, including opsin, and for the survival of retinal photoreceptor cells, rendering the ift122 mutant a unique model for human retinal degenerative diseases. PMID:27681595

Diffraction inspired unidirectional and bidirectional beam splitting in defect-containing photonic structures without interface corrugations

DOE Office of Scientific and Technical Information (OSTI.GOV)

Colak, Evrim; Serebryannikov, Andriy E., E-mail: andser@amu.edu.pl; Usik, P. V.

2016-05-21

It is shown that strong diffractions and related dual-beam splitting can be obtained at transmission through the nonsymmetric structures that represent two slabs of photonic crystal (PhC) separated by a single coupled-cavity type defect layer, while there are no grating-like corrugations at the interfaces. The basic operation regimes include unidirectional and bidirectional splitting that occur due to the dominant contribution of the first positive and first negative diffraction orders to the transmission, which is typically connected with different manifestations of the asymmetric transmission phenomenon. Being the main component of the resulting transmission mechanism, diffractions appear owing to the effect exertedmore » by the defect layer that works like an embedded diffractive element. Two mechanisms can co-exist in one structure, which differ, among others, in that whether dispersion allows coupling of zero order to a wave propagating in the regular, i.e., defect-free PhC segments or not. The possibility of strong diffractions and efficient splitting related to it strongly depend on the dispersion properties of the Floquet-Bloch modes of the PhC. Existence of one of the studied transmission scenarios is not affected by location of the defect layer.« less

Prevalence of birth defects among American-Indian births in California, 1983-2010.

PubMed

Aggarwal, Deepa; Warmerdam, Barbara; Wyatt, Katrina; Ahmad, Shabbir; Shaw, Gary M

2015-02-01

Approximately 6.3 million live births and fetal deaths occurred during the ascertainment period in the California Birth Defects Monitoring Program registry. American-Indian and non-Hispanic white women delivered 40,268 and 2,044,118 births, respectively. While much information has been published about non-Hispanic white infants, little is known regarding the risks of birth defects among infants born to American-Indian women. This study used data from the California Birth Defects Monitoring Program to explore risks of selected birth defects in offspring of American-Indian relative to non-Hispanic white women in California. The study population included all live births and fetal deaths 20 weeks or greater from 1983 to 2010. Prevalence ratios and corresponding 95% confidence intervals (CI) were computed using Poisson regression for 51 groupings of birth defects. Prevalence ratios were estimated for 51 groupings of birth defects. Of the 51, nine had statistically precise results ranging from 0.78 to 1.85. The eight groups with elevated risks for American-Indian births were reduction deformities of brain, anomalies of anterior segments, specified anomalies of ear, ostium secundum type atrial septal defect, specified anomalies of heart, anomalies of the aorta, anomalies of great veins, and cleft lip with cleft palate. Our results suggest that American-Indian women having babies in California may be at higher risk for eight birth defect phenotypes compared with non-Hispanic whites. Further research is needed to determine whether these risks are observed among other populations of American-Indian women or when adjusted for potential covariates. © 2015 Wiley Periodicals, Inc.

Vectorization of optically sectioned brain microvasculature: learning aids completion of vascular graphs by connecting gaps and deleting open-ended segments.

PubMed

Kaufhold, John P; Tsai, Philbert S; Blinder, Pablo; Kleinfeld, David

2012-08-01

A graph of tissue vasculature is an essential requirement to model the exchange of gasses and nutriments between the blood and cells in the brain. Such a graph is derived from a vectorized representation of anatomical data, provides a map of all vessels as vertices and segments, and may include the location of nonvascular components, such as neuronal and glial somata. Yet vectorized data sets typically contain erroneous gaps, spurious endpoints, and spuriously merged strands. Current methods to correct such defects only address the issue of connecting gaps and further require manual tuning of parameters in a high dimensional algorithm. To address these shortcomings, we introduce a supervised machine learning method that (1) connects vessel gaps by "learned threshold relaxation"; (2) removes spurious segments by "learning to eliminate deletion candidate strands"; and (3) enforces consistency in the joint space of learned vascular graph corrections through "consistency learning." Human operators are only required to label individual objects they recognize in a training set and are not burdened with tuning parameters. The supervised learning procedure examines the geometry and topology of features in the neighborhood of each vessel segment under consideration. We demonstrate the effectiveness of these methods on four sets of microvascular data, each with >800(3) voxels, obtained with all optical histology of mouse tissue and vectorization by state-of-the-art techniques in image segmentation. Through statistically validated sampling and analysis in terms of precision recall curves, we find that learning with bagged boosted decision trees reduces equal-error error rates for threshold relaxation by 5-21% and strand elimination performance by 18-57%. We benchmark generalization performance across datasets; while improvements vary between data sets, learning always leads to a useful reduction in error rates. Overall, learning is shown to more than halve the total error rate, and therefore, human time spent manually correcting such vectorizations. Copyright © 2012 Elsevier B.V. All rights reserved.

Vectorization of optically sectioned brain microvasculature: Learning aids completion of vascular graphs by connecting gaps and deleting open-ended segments

PubMed Central

Kaufhold, John P.; Tsai, Philbert S.; Blinder, Pablo; Kleinfeld, David

2012-01-01

A graph of tissue vasculature is an essential requirement to model the exchange of gasses and nutriments between the blood and cells in the brain. Such a graph is derived from a vectorized representation of anatomical data, provides a map of all vessels as vertices and segments, and may include the location of nonvascular components, such as neuronal and glial somata. Yet vectorized data sets typically contain erroneous gaps, spurious endpoints, and spuriously merged strands. Current methods to correct such defects only address the issue of connecting gaps and further require manual tuning of parameters in a high dimensional algorithm. To address these shortcomings, we introduce a supervised machine learning method that (1) connects vessel gaps by “learned threshold relaxation”; (2) removes spurious segments by “learning to eliminate deletion candidate strands”; and (3) enforces consistency in the joint space of learned vascular graph corrections through “consistency learning.” Human operators are only required to label individual objects they recognize in a training set and are not burdened with tuning parameters. The supervised learning procedure examines the geometry and topology of features in the neighborhood of each vessel segment under consideration. We demonstrate the effectiveness of these methods on four sets of microvascular data, each with > 8003 voxels, obtained with all optical histology of mouse tissue and vectorization by state-of-the-art techniques in image segmentation. Through statistically validated sampling and analysis in terms of precision recall curves, we find that learning with bagged boosted decision trees reduces equal-error error rates for threshold relaxation by 5 to 21 % and strand elimination performance by 18 to 57 %. We benchmark generalization performance across datasets; while improvements vary between data sets, learning always leads to a useful reduction in error rates. Overall, learning is shown to more than halve the total error rate, and therefore, human time spent manually correcting such vectorizations. PMID:22854035

Space Shuttle Orbiter Wing-Leading-Edge Panel Thermo-Mechanical Analysis for Entry Conditions

NASA Technical Reports Server (NTRS)

Knight, Norman F., Jr.; Song, Kyongchan; Raju, Ivatury S.

2010-01-01

Linear elastic, thermo-mechanical stress analyses of the Space Shuttle Orbiter wing-leading-edge panels is presented for entry heating conditions. The wing-leading-edge panels are made from reinforced carbon-carbon and serve as a part of the overall thermal protection system. Three-dimensional finite element models are described for three configurations: integrated configuration, an independent single-panel configuration, and a local lower-apex joggle segment. Entry temperature conditions are imposed and the through-the-thickness response is examined. From the integrated model, it was concluded that individual panels can be analyzed independently since minimal interaction between adjacent components occurred. From the independent single-panel model, it was concluded that increased through-the-thickness stress levels developed all along the chord of a panel s slip-side joggle region, and hence isolated local joggle sections will exhibit the same trend. From the local joggle models, it was concluded that two-dimensional plane-strain models can be used to study the influence of subsurface defects along the slip-side joggle region of these panels.

Pondering the procephalon: the segmental origin of the labrum.

PubMed

Haas, M S; Brown, S J; Beeman, R W

2001-02-01

With accumulating evidence for the appendicular nature of the labrum, the question of its actual segmental origin remains. Two existing insect head segmentation models, the linear and S-models, are reviewed, and a new model introduced. The L-/Bent-Y model proposes that the labrum is a fusion of the appendage endites of the intercalary segment and that the stomodeum is tightly integrated into this segment. This model appears to explain a wider variety of insect head segmentation phenomena. Embryological, histological, neurological and molecular evidence supporting the new model is reviewed.

Identification of eight mutations and three sequence variations in the cystic fibrosis transmembrane conductance regulator (CFTR) gene

DOE Office of Scientific and Technical Information (OSTI.GOV)

Ghanem, N.; Costes, B.; Girodon, E.

1994-05-15

To determine cystic fibrosis (CF) defects in a sample of 224 non-[Delta]F508 CF chromosomes, the authors used denaturing gradient gel multiplex analysis of CF transmembrane conductance regulator gene segments, a strategy based on blind exhaustive analysis rather than a search for known mutations. This process allowed detection of 11 novel variations comprising two nonsense mutations (Q890X and W1204X), a splice defect (405 + 4 A [yields] G), a frameshift (3293delA), four presumed missense mutations (S912L, H949Y, L1065P, Q1071P), and three sequence polymorphisms (R31C or 223 C/T, 3471 T/C, and T1220I or 3791 C/T). The authors describe these variations, together withmore » the associated phenotype when defects on both CF chromosomes were identified. 8 refs., 1 fig., 1 tab.« less

Creation of an ensemble of simulated cardiac cases and a human observer study: tools for the development of numerical observers for SPECT myocardial perfusion imaging

NASA Astrophysics Data System (ADS)

O'Connor, J. Michael; Pretorius, P. Hendrik; Gifford, Howard C.; Licho, Robert; Joffe, Samuel; McGuiness, Matthew; Mehurg, Shannon; Zacharias, Michael; Brankov, Jovan G.

2012-02-01

Our previous Single Photon Emission Computed Tomography (SPECT) myocardial perfusion imaging (MPI) research explored the utility of numerical observers. We recently created two hundred and eighty simulated SPECT cardiac cases using Dynamic MCAT (DMCAT) and SIMIND Monte Carlo tools. All simulated cases were then processed with two reconstruction methods: iterative ordered subset expectation maximization (OSEM) and filtered back-projection (FBP). Observer study sets were assembled for both OSEM and FBP methods. Five physicians performed an observer study on one hundred and seventy-nine images from the simulated cases. The observer task was to indicate detection of any myocardial perfusion defect using the American Society of Nuclear Cardiology (ASNC) 17-segment cardiac model and the ASNC five-scale rating guidelines. Human observer Receiver Operating Characteristic (ROC) studies established the guidelines for the subsequent evaluation of numerical model observer (NO) performance. Several NOs were formulated and their performance was compared with the human observer performance. One type of NO was based on evaluation of a cardiac polar map that had been pre-processed using a gradient-magnitude watershed segmentation algorithm. The second type of NO was also based on analysis of a cardiac polar map but with use of a priori calculated average image derived from an ensemble of normal cases.

Differential loss of striatal projection neurons in Huntington disease

DOE Office of Scientific and Technical Information (OSTI.GOV)

Reiner, A.; Albin, R.L.; Anderson, K.D.

1988-08-01

Huntington disease (HD) is characterized by the loss of striatal projection neurons, which constitute the vast majority of striatal neurons. To determine whether there is differential loss among different populations of striatal projection neurons, the integrity of the axon terminal plexuses arising from the different populations of substance P-containing and enkephalin-containing striatal projection neurons was studied in striatal target areas by immunohistochemistry. Analysis of 17 HD specimens indicated that in early and middle stages of HD, enkephalin-containing neurons projecting to the external segment of the globus pallidus were much more affected than substance P-containing neurons projecting to the internal pallidalmore » segment. Furthermore, substance P-containing neurons projecting to the substantia nigra pars reticulata were more affected than those projecting to the substantia nigra pars compacta. At the most advanced stages of the disease, projections to all striatal target areas were depleted, with the exception of some apparent sparing of the striatal projection to the substantia nigra pars compacta. These finding may explain some of the clinical manifestations and pharmacology of HD. They also may aid in identifying the neural defect underlying HD and provide additional data with which to evaluate current models of HD pathogenesis.« less

Numerical optimization of open-porous bone scaffold structures to match the elastic properties of human cortical bone.

PubMed

Wieding, Jan; Wolf, Andreas; Bader, Rainer

2014-09-01

Treatment of large segmental bone defects, especially in load bearing areas, is a complex procedure in orthopedic surgery. The usage of additive manufacturing processes enables the creation of customized bone implants with arbitrary open-porous structure satisfying both the mechanical and the biological requirements for a sufficient bone ingrowth. Aim of the present numerical study was to optimize the geometrical parameters of open-porous titanium scaffolds to match the elastic properties of human cortical bone with respect to an adequate pore size. Three different scaffold designs (cubic, diagonal and pyramidal) were numerically investigated by using an optimization approach. Beam elements were used to create the lattice structures of the scaffolds. The design parameters strut diameter and pore size ranged from 0.2 to 1.5mm and from 0 to 3.0mm, respectively. In a first optimization step, the geometrical parameters were varied under uniaxial compression to obtain a structural modulus of 15GPa (Young׳s modulus of cortical bone) and a pore size of 800µm was aimed to enable cell ingrowth. Furthermore, the mechanical behavior of the optimized structures under bending and torsion was investigated. Results for bending modulus were between 9.0 and 14.5GPa. In contrast, shear modulus was lowest for cubic and pyramidal design of approximately 1GPa. Here, the diagonal design revealed a modulus of nearly 20GPa. In a second step, large-sized bone scaffolds were created and placed in a biomechanical loading situation within a 30mm segmental femoral defect, stabilized with an osteosynthesis plate and loaded with physiological muscle forces. Strut diameter for the 17 sections of each scaffold was optimized independently in order to match the biomechanical stability of intact bone. For each design, highest strut diameter was found at the dorsal/medial site of the defect and smallest strut diameter in the center. In conclusion, we demonstrated the possibility of providing optimized open-porous scaffolds for bone regeneration by considering both mechanical and biological aspects. Furthermore, the results revealed the need of the investigation and comparison of different load scenarios (compression, bending and torsion) as well as complex biomechanical loading for a profound characterization of different scaffold designs. The usage of a numerical optimization process was proven to be a feasible tool to reduce the amount of the required titanium material without influencing the biomechanical performance of the scaffold negatively. By using fully parameterized models, the optimization approach is adaptable to other scaffold designs and bone defect situations. Copyright © 2014 Elsevier Ltd. All rights reserved.

Ion-irradiation-induced microstructural modifications in ferritic/martensitic steel T91

DOE Office of Scientific and Technical Information (OSTI.GOV)

Liu, Xiang; Miao, Yinbin; Li, Meimei

In this paper, in situ transmission electron microscopy investigations were carried out to study the microstructural evolution of ferritic/martensitic steel T91 under 1 MeV Krypton ion irradiation up to 4.2 x 10(15) ions/cm(2) at 573 K, 673 K, and 773 K. At 573 K, grown-in defects are strongly modified by black dot loops, and dislocation networks together with black-dot loops were observed after irradiation. At 673 K and 773 K, grown-in defects are only partially modified by dislocation loops; isolated loops and dislocation segments were commonly found after irradiation. Post irradiation examination indicates that at 4.2 x 1015 ions/cm(2), aboutmore » 51% of the loops were a(0)/2 < 111 > type for the 673 K irradiation, and the dominant loop type was a(0)< 100 > for the 773 K irradiation. Finally, a dispersed barrier hardening model was employed to estimate the change in yield strength, and the calculated ion data were found to follow the similar trend as the existing neutron data with an offset of 100-150 MPa. (C) 2017 Elsevier B.V. All rights reserved.« less

Update on Foregut Molecular Embryology and Role of Regenerative Medicine Therapies

PubMed Central

Perin, Silvia; McCann, Conor J.; Borrelli, Osvaldo; De Coppi, Paolo; Thapar, Nikhil

2017-01-01

Esophageal atresia (OA) represents one of the commonest and most severe developmental disorders of the foregut, the most proximal segment of the gastrointestinal (GI) tract (esophagus and stomach) in embryological terms. Of intrigue is the common origin from this foregut of two very diverse functional entities, the digestive and respiratory systems. OA appears to result from incomplete separation of the ventral and dorsal parts of the foregut during development, resulting in disruption of esophageal anatomy and frequent association with tracheo-oesophageal fistula. Not surprisingly, and likely inherent to OA, are associated abnormalities in components of the enteric neuromusculature and ultimately loss of esophageal functional integrity. An appreciation of such developmental processes and associated defects has not only enhanced our understanding of the etiopathogenesis underlying such devastating defects but also highlighted the potential of novel corrective therapies. There has been considerable progress in the identification and propagation of neural crest stem cells from the GI tract itself or derived from pluripotent cells. Such cells have been successfully transplanted into models of enteric neuropathy confirming their ability to functionally integrate and replenish missing or defective enteric nerves. Combinatorial approaches in tissue engineering hold significant promise for the generation of organ-specific scaffolds such as the esophagus with current initiatives directed toward their cellularization to facilitate optimal function. This chapter outlines the most current understanding of the molecular embryology underlying foregut development and OA, and also explores the promise of regenerative medicine. PMID:28503544

Update on Foregut Molecular Embryology and Role of Regenerative Medicine Therapies.

PubMed

Perin, Silvia; McCann, Conor J; Borrelli, Osvaldo; De Coppi, Paolo; Thapar, Nikhil

2017-01-01

Esophageal atresia (OA) represents one of the commonest and most severe developmental disorders of the foregut, the most proximal segment of the gastrointestinal (GI) tract (esophagus and stomach) in embryological terms. Of intrigue is the common origin from this foregut of two very diverse functional entities, the digestive and respiratory systems. OA appears to result from incomplete separation of the ventral and dorsal parts of the foregut during development, resulting in disruption of esophageal anatomy and frequent association with tracheo-oesophageal fistula. Not surprisingly, and likely inherent to OA, are associated abnormalities in components of the enteric neuromusculature and ultimately loss of esophageal functional integrity. An appreciation of such developmental processes and associated defects has not only enhanced our understanding of the etiopathogenesis underlying such devastating defects but also highlighted the potential of novel corrective therapies. There has been considerable progress in the identification and propagation of neural crest stem cells from the GI tract itself or derived from pluripotent cells. Such cells have been successfully transplanted into models of enteric neuropathy confirming their ability to functionally integrate and replenish missing or defective enteric nerves. Combinatorial approaches in tissue engineering hold significant promise for the generation of organ-specific scaffolds such as the esophagus with current initiatives directed toward their cellularization to facilitate optimal function. This chapter outlines the most current understanding of the molecular embryology underlying foregut development and OA, and also explores the promise of regenerative medicine.

NRC/AMRMC Resident Research Associateship Program

DTIC Science & Technology

2015-03-01

antimicrobials (and antiseptics) as well as to evaluate the effectiveness of various biofilm dispersal agents utilizing a number of bacterial species as well...combat related wounds. 3 Demonstrated the utility of combinations of biofilm dispersal agents and antimicrobials as an alternate therapy for targeting...alone or in combination with antimicrobials ) to reduce infection in contaminated femoral segmental defects. 5 Characterized host responses of

Optimizing Soft Tissue Management and Spacer Design in Segmental Bone Defects

DTIC Science & Technology

2015-10-01

were found with Tukey’s HSD post hoc analysis. Several target genes such as Oct4, Sox2, TGFB, and Col1A1 were generally up-regulated in all sections...samples presented several upregulated target genes such as Oct4, Sox2, TGFB, and Col1A1 in all sections. No significant main effects were found for

A Silvicultural Evaluation of Four Methods of Marking Second-growth Northern Hardwood Stands

Treesearch

Rodney D. Jacobs

1966-01-01

Second-growth northern hardwood stands occupy an important segment of the commercial forest land of Upper Michigan and northern Wisconsin. The size- and age-class distributions and species composition of these stands vary considerably, but under all conditions most of the trees are highly defective or poorly formed or of an undesirable species. Forest managers...

Expression and function of the zinc finger transcription factor Sp6-9 in the spider Parasteatoda tepidariorum.

PubMed

Königsmann, Tatiana; Turetzek, Natascha; Pechmann, Matthias; Prpic, Nikola-Michael

2017-11-01

Zinc finger transcription factors of the Sp6-9 group are evolutionarily conserved in all metazoans and have important functions in, e.g., limb formation and heart development. The function of Sp6-9-related genes has been studied in a number of vertebrates and invertebrates, but data from chelicerates (spiders and allies) was lacking so far. We have isolated the ortholog of Sp6-9 from the common house spider Parasteatoda tepidariorum and the cellar spider Pholcus phalangioides. We show that the Sp6-9 gene in these spider species is expressed in the developing appendages thus suggesting a conserved role in limb formation. Indeed, RNAi with Sp6-9 in P. tepidariorum leads not only to strong limb defects, but also to the loss of body segments and head defects in more strongly affected animals. Together with a new expression domain in the early embryo, these data suggest that Sp6-9 has a dual role P. tepidariorum. The early role in head and body segment formation is not known from other arthropods, but the role in limb formation is evolutionarily highly conserved.

Success rate and risk factors of failure of the induced membrane technique in children: a systematic review.

PubMed

Aurégan, Jean-Charles; Bégué, Thierry; Rigoulot, Guillaume; Glorion, Christophe; Pannier, Stéphanie

2016-12-01

The induced membrane technique was designed by Masquelet et al. to address segmental bone defects of critical size in adults. It has been used after bone defects of traumatic, infectious and tumoral origin with satisfactory results. Recently, it has been used in children but, after an initial enthusiasm, several cases of failure have been reported. The purpose of this study was to assess the success rate and the risk factors of failure of the induced membrane for children. We conducted a systematic review of all the studies reporting the results of the induced membrane technique to address bone defects of critical size in children. Our primary outcome was the success rate of the technique defined as a bone union before any iterative surgery. Our secondary outcomes were the complications and the risk factors of failure. We searched Medline via Pubmed, EMBASE and the Cochrane Library. Twelve studies, including 69 patients, met the inclusion criteria. There were 41 boys and 28 girls. Mean age at surgery was 10 years. Mean size of resection was 12.38 cm and the mean time between the two stages was 5.86 months. Mean rate of bone union after the two stages of the induced membrane technique was 58% (40/69) but this rate increased to 87% after revision surgeries (60/69). Main complications were non-unions (19/69), lysis of the graft (6/69) and fractures of the bone graft (6/69). Only 1/69 deep infection was reported. Other non specific complications were regularly reported such limb length discrepancies, joint stiffness and protruding wires. Risk factor of failure that could be suspected comprised the resection of a malignant tumour, a bone defect located at the femur, a wide resection, a long time between the two stages, an unstable osteosynthesis and a bone graft associating autograft to other graft materials. The induced membrane technique is suitable for bone defects of critical size in children. It is a reliable technique with no need of micro vascular surgery. However, we found several risk factors of failure for the use of the induced membrane technique to address segmental bone defect of critical size in children. Copyright © 2016 Elsevier Ltd. All rights reserved.

[Analysis of genomic copy number variations in two unrelated neonates with 8p deletion and duplication associated with congenital heart disease].

PubMed

Mei, Mei; Yang, Lin; Zhan, Guodong; Wang, Huijun; Ma, Duan; Zhou, Wenhao; Huang, Guoying

2014-06-01

To screen for genomic copy number variations (CNVs) in two unrelated neonates with multiple congenital abnormalities using Affymetrix SNP chip and try to find the critical region associated with congenital heart disease. Two neonates were tested for genomic copy number variations by using Cytogenetic SNP chip.Rare CNVs with potential clinical significance were selected of which deletion segments' size was larger than 50 kb and duplication segments' size was larger than 150 kb based on the analysis of ChAs software, without false positive CNVs and segments of normal population. The identified CNVs were compared with those of the cases in DECIPHER and ISCA databases. Eleven rare CNVs with size from 546.6-27 892 kb were identified in the 2 neonates. The deletion region and size of case 1 were 8p23.3-p23.1 (387 912-11 506 771 bp) and 11.1 Mb respectively, the duplication region and size of case 1 were 8p23.1-p11.1 (11 508 387-43 321 279 bp) and 31.8 Mb respectively. The deletion region and size of case 2 were 8p23.3-p23.1 (46 385-7 809 878 bp) and 7.8 Mb respectively, the duplication region and size of case 2 were 8p23.1-p11.21 (12 260 914-40 917 092 bp) and 28.7 Mb respectively. The comparison with Decipher and ISCA databases supported previous viewpoint that 8p23.1 had been associated with congenital heart disease and the region between 7 809 878-11 506 771 bp may play a role in the severe cardiac defects associated with 8p23.1 deletions. Case 1 had serious cardiac abnormalities whose GATA4 was located in the duplication segment and the copy number increased while SOX7 was located in the deletion segment and the copy number decreased. The region between 7 809 878-11 506 771 bp in 8p23.1 is associated with heart defects and copy number variants of SOX7 and GATA4 may result in congenital heart disease.

A segmentation/clustering model for the analysis of array CGH data.

PubMed

Picard, F; Robin, S; Lebarbier, E; Daudin, J-J

2007-09-01

Microarray-CGH (comparative genomic hybridization) experiments are used to detect and map chromosomal imbalances. A CGH profile can be viewed as a succession of segments that represent homogeneous regions in the genome whose representative sequences share the same relative copy number on average. Segmentation methods constitute a natural framework for the analysis, but they do not provide a biological status for the detected segments. We propose a new model for this segmentation/clustering problem, combining a segmentation model with a mixture model. We present a new hybrid algorithm called dynamic programming-expectation maximization (DP-EM) to estimate the parameters of the model by maximum likelihood. This algorithm combines DP and the EM algorithm. We also propose a model selection heuristic to select the number of clusters and the number of segments. An example of our procedure is presented, based on publicly available data sets. We compare our method to segmentation methods and to hidden Markov models, and we show that the new segmentation/clustering model is a promising alternative that can be applied in the more general context of signal processing.

Thermodynamic confinement and alpha-helix persistence length in poly(gamma-benzyl-L-glutamate)-b-poly(dimethyl siloxane)-b-poly(gamma-benzyl-L-glutamate) triblock copolymers.

PubMed

Papadopoulos, P; Floudas, G; Schnell, I; Lieberwirth, I; Nguyen, T Q; Klok, H-A

2006-02-01

The structure and the associated dynamics of a series of poly(gamma-benzyl-L-glutamate)-b-poly(dimethyl siloxane)-b-poly(gamma-benzyl-L-glutamate) (PBLG-b-PDMS-b-PBLG) triblock copolymers were investigated using small- and wide-angle X-ray scattering, NMR, transmission electron microscopy, and dielectric spectroscopy, respectively. The structural analysis revealed phase separation in the case of the longer blocks with defected alpha-helical segments embedded within the block copolymer nanodomains. The alpha-helical persistence length was found to depend on the degree of segregation; thermodynamic confinement and chain stretching results in the partial annihilation of helical defects.

Role of subunit assembly in autosomal dominant retinitis pigmentosa linked to mutations in peripherin 2.

PubMed

Molday, Robert S; Molday, Laurie L; Loewen, Christopher J R

2004-01-01

Peripherin 2 is a photoreceptor-specific membrane protein implicated in outer segment disk morphogenesis and linked to various retinopathies including autosomal dominant retinitis pigmentosa (ADRP). Peripherin 2 and ROM1 assemble as a mixture of core noncovalent homomeric and heteromeric tetramers that further link together through disulfide bonds to form higher order oligomers. These complexes are critical for disk rim formation and outer segment structure through interaction with the cGMP-gated channel and other photoreceptor proteins. We have examined the role of subunit assembly in peripherin 2 targeting to disks, outer segment structure, and photoreceptor degeneration by examining molecular and cellular properties of peripherin 2 mutants in COS-1 cells and transgenic Xenopus laevis rod photoreceptors. Wild-type (WT) and the ADRP-linked P216L mutant were transported and incorporated into newly formed outer segment disks of transgenic X. laevis. The P216L mutant, however, induced progressive outer segment instability and photoreceptor degeneration possibly through the introduction of a new N-linked oligosaccharide chain. In contrast, the C214S and L185P disease-linked, tetramerization-defective mutants, were retained in the inner segment, but did not affect outer segment structure or induce photoreceptor degeneration. Together, these results indicate that peripherin 2 mutations can cause ADRP either through a deficiency in WT peripherin 2 (C214S, 1.185P) or by a dominant negative effect on disk stability (P216L).

Impact of CT perfusion imaging on the assessment of peripheral chronic pulmonary thromboembolism: clinical experience in 62 patients.

PubMed

Le Faivre, Julien; Duhamel, Alain; Khung, Suonita; Faivre, Jean-Baptiste; Lamblin, Nicolas; Remy, Jacques; Remy-Jardin, Martine

2016-11-01

To evaluate the impact of CT perfusion imaging on the detection of peripheral chronic pulmonary embolisms (CPE). 62 patients underwent a dual-energy chest CT angiographic examination with (a) reconstruction of diagnostic and perfusion images; (b) enabling depiction of vascular features of peripheral CPE on diagnostic images and perfusion defects (20 segments/patient; total: 1240 segments examined). The interpretation of diagnostic images was of two types: (a) standard (i.e., based on cross-sectional images alone) or (b) detailed (i.e., based on cross-sectional images and MIPs). The segment-based analysis showed (a) 1179 segments analyzable on both imaging modalities and 61 segments rated as nonanalyzable on perfusion images; (b) the percentage of diseased segments was increased by 7.2 % when perfusion imaging was compared to the detailed reading of diagnostic images, and by 26.6 % when compared to the standard reading of images. At a patient level, the extent of peripheral CPE was higher on perfusion imaging, with a greater impact when compared to the standard reading of diagnostic images (number of patients with a greater number of diseased segments: n = 45; 72.6 % of the study population). Perfusion imaging allows recognition of a greater extent of peripheral CPE compared to diagnostic imaging. • Dual-energy computed tomography generates standard diagnostic imaging and lung perfusion analysis. • Depiction of CPE on central arteries relies on standard diagnostic imaging. • Detection of peripheral CPE is improved by perfusion imaging.

Two and three-dimensional segmentation of hyperpolarized 3He magnetic resonance imaging of pulmonary gas distribution

NASA Astrophysics Data System (ADS)

Heydarian, Mohammadreza; Kirby, Miranda; Wheatley, Andrew; Fenster, Aaron; Parraga, Grace

2012-03-01

A semi-automated method for generating hyperpolarized helium-3 (3He) measurements of individual slice (2D) or whole lung (3D) gas distribution was developed. 3He MRI functional images were segmented using two-dimensional (2D) and three-dimensional (3D) hierarchical K-means clustering of the 3He MRI signal and in addition a seeded region-growing algorithm was employed for segmentation of the 1H MRI thoracic cavity volume. 3He MRI pulmonary function measurements were generated following two-dimensional landmark-based non-rigid registration of the 3He and 1H pulmonary images. We applied this method to MRI of healthy subjects and subjects with chronic obstructive lung disease (COPD). The results of hierarchical K-means 2D and 3D segmentation were compared to an expert observer's manual segmentation results using linear regression, Pearson correlations and the Dice similarity coefficient. 2D hierarchical K-means segmentation of ventilation volume (VV) and ventilation defect volume (VDV) was strongly and significantly correlated with manual measurements (VV: r=0.98, p<.0001 VDV: r=0.97, p<.0001) and mean Dice coefficients were greater than 92% for all subjects. 3D hierarchical K-means segmentation of VV and VDV was also strongly and significantly correlated with manual measurements (VV: r=0.98, p<.0001 VDV: r=0.64, p<.0001) and the mean Dice coefficients were greater than 91% for all subjects. Both 2D and 3D semi-automated segmentation of 3He MRI gas distribution provides a way to generate novel pulmonary function measurements.

Characteristics of Urban Sidewalks/Streets and Objectively Measured Physical Activity

PubMed Central

Heinrich, Katie M.; Poston, Walker S.C.; Hyder, Melissa; Pyle, Sara

2007-01-01

Several studies have found significant relationships between environmental characteristics (e.g., number of destinations, aesthetics) and physical activity. While a few of these studies verified that the physical activities assessed were performed in the environments examined, none have done this in an urban, neighborhood setting. This information will help efforts to inform policy decisions regarding the design of more “physically active” communities. Fourteen environmental characteristics of 60, 305-m-long segments, located in an urban, residential setting, were directly measured using standardized procedures. The number of individuals walking, jogging, and biking in the segments was assessed using an observation technique. The segments were heterogeneous with regards to several of the environmental characteristics. A total of 473 individuals were seen walking, bicycling, or jogging in the segments during 3,600 min of observation (60 min/segment). Of the 473 seen, 315 were walking, 116 bicycling, and 42 jogging. A greater number of individuals were seen walking in segments with more traffic, sidewalk defects, graffiti, and litter and less desirable property aesthetics. Only one environmental characteristic was associated with bicycling and none were significantly related with jogging. This study provides further evidence that environmental characteristics and walking are related. It also adds new information regarding the importance of scale (e.g., micro, macro) and how some environmental characteristics of urban, residential sidewalks and streets relate to physical activity. PMID:18161026

Skull Defects in Finite Element Head Models for Source Reconstruction from Magnetoencephalography Signals

PubMed Central

Lau, Stephan; Güllmar, Daniel; Flemming, Lars; Grayden, David B.; Cook, Mark J.; Wolters, Carsten H.; Haueisen, Jens

2016-01-01

Magnetoencephalography (MEG) signals are influenced by skull defects. However, there is a lack of evidence of this influence during source reconstruction. Our objectives are to characterize errors in source reconstruction from MEG signals due to ignoring skull defects and to assess the ability of an exact finite element head model to eliminate such errors. A detailed finite element model of the head of a rabbit used in a physical experiment was constructed from magnetic resonance and co-registered computer tomography imaging that differentiated nine tissue types. Sources of the MEG measurements above intact skull and above skull defects respectively were reconstructed using a finite element model with the intact skull and one incorporating the skull defects. The forward simulation of the MEG signals reproduced the experimentally observed characteristic magnitude and topography changes due to skull defects. Sources reconstructed from measured MEG signals above intact skull matched the known physical locations and orientations. Ignoring skull defects in the head model during reconstruction displaced sources under a skull defect away from that defect. Sources next to a defect were reoriented. When skull defects, with their physical conductivity, were incorporated in the head model, the location and orientation errors were mostly eliminated. The conductivity of the skull defect material non-uniformly modulated the influence on MEG signals. We propose concrete guidelines for taking into account conducting skull defects during MEG coil placement and modeling. Exact finite element head models can improve localization of brain function, specifically after surgery. PMID:27092044

Defect-Repairable Latent Feature Extraction of Driving Behavior via a Deep Sparse Autoencoder

PubMed Central

Taniguchi, Tadahiro; Takenaka, Kazuhito; Bando, Takashi

2018-01-01

Data representing driving behavior, as measured by various sensors installed in a vehicle, are collected as multi-dimensional sensor time-series data. These data often include redundant information, e.g., both the speed of wheels and the engine speed represent the velocity of the vehicle. Redundant information can be expected to complicate the data analysis, e.g., more factors need to be analyzed; even varying the levels of redundancy can influence the results of the analysis. We assume that the measured multi-dimensional sensor time-series data of driving behavior are generated from low-dimensional data shared by the many types of one-dimensional data of which multi-dimensional time-series data are composed. Meanwhile, sensor time-series data may be defective because of sensor failure. Therefore, another important function is to reduce the negative effect of defective data when extracting low-dimensional time-series data. This study proposes a defect-repairable feature extraction method based on a deep sparse autoencoder (DSAE) to extract low-dimensional time-series data. In the experiments, we show that DSAE provides high-performance latent feature extraction for driving behavior, even for defective sensor time-series data. In addition, we show that the negative effect of defects on the driving behavior segmentation task could be reduced using the latent features extracted by DSAE. PMID:29462931

Bilobed perforator free flaps for combined hemitongue and floor-of-the-mouth defects.

PubMed

Longo, B; Ferri, G; Fiorillo, A; Rubino, C; Santanelli, F

2013-11-01

Combined hemiglossectomy and floor-of-the-mouth defects need accurate reconstructive planning to restore swallowing and speech function. The aim of this prospective study was to evaluate outcomes of the bilobed design applied to perforator free flaps for combined hemitongue and floor-of-the-mouth defects. Twelve patients with a mean age of 71 years (range, 60-84) addressed to combined hemiglossectomy and floor-of-the-mouth resection and bilobed-shaped perforator free-flap reconstruction were prospectively enrolled. Defects were classified as follows: type 1, including only the anterior mobile portion of the tongue (n = 3); type 2, involving both mobile tongue and tongue base (n = 6); and type 3, including segmental mandibulectomy combined with a type 1 or type 2 defect (n = 3). The Kruskal-Wallis and Bonferroni post hoc tests were used to compare outcomes. Type 1 defects were reconstructed by three anterolateral thigh (ALT) perforator flaps; type 2 defects were reconstructed by four ALT flaps and two vertical deep inferior epigastric perforator flaps; and type 3 defects were restored by three osteocutaneous fibula flaps. Eleven flaps (91.6%) healed uneventfully, while one (8.4%) suffered a small area of skin necrosis whose revision did not compromise functional results. Six patients achieved normal intelligible speech, five had acceptable intelligible speech and one had unintelligible speech (p = 0.356). Swallowing function was considered normal in eight patients and with mild impairment in four (p = 0.178). Cosmesis resulted excellent in seven patients and good in five (p = 0.855). The bilobed-shaped perforator free flaps were shown to be a safe and predictable solution for combined hemitongue and floor-of-the-mouth defects providing optimal aesthetic and functional outcomes. Copyright © 2013 British Association of Plastic, Reconstructive and Aesthetic Surgeons. Published by Elsevier Ltd. All rights reserved.

How do patients with neglect see a horizontal line? Analysis of performances in coloured line bisection task.

PubMed

Misonou, Kaori; Ishiai, Sumio; Seki, Keiko; Koyama, Yasumasa; Nakano, Naomi

2004-06-01

Twelve patients with left unilateral spatial neglect were examined with a newly devised "coloured line bisection task". They were presented with a horizontal line printed in blue on one side and in red on the other side; the proportions of the blue and red segments were varied. Immediately after placement of the subjective midpoint, the line was concealed and the patients were asked to name the colours of the right and left ends. Five patients who identified the left-end colour almost correctly had no visual field defect, while the other seven whose colour naming was impaired on the left side had left visual field defect. The rightward bisection errors were similarly distributed in the fair and poor colour-naming patients except for two patients from the latter group. The lesions of the fair colour-naming patients spared the lingual and fusiform gyri, which are known to be engaged in colour processing. Patients with neglect whose visual field is preserved may neglect the leftward extension of a line but not the colour in the neglected space. The poor colour-naming patients frequently failed to name the left-end colour that appeared to the left of their subjective midpoint, which indicates that they hardly searched leftward beyond that point. In such trials, they reported that the left end had the same colour as the right end. The results suggest that in patients with neglect and left visual field defect, both the leftward extent and the colour of a line may be represented on the basis of the information from the attended right segment.

A label field fusion bayesian model and its penalized maximum rand estimator for image segmentation.

PubMed

Mignotte, Max

2010-06-01

This paper presents a novel segmentation approach based on a Markov random field (MRF) fusion model which aims at combining several segmentation results associated with simpler clustering models in order to achieve a more reliable and accurate segmentation result. The proposed fusion model is derived from the recently introduced probabilistic Rand measure for comparing one segmentation result to one or more manual segmentations of the same image. This non-parametric measure allows us to easily derive an appealing fusion model of label fields, easily expressed as a Gibbs distribution, or as a nonstationary MRF model defined on a complete graph. Concretely, this Gibbs energy model encodes the set of binary constraints, in terms of pairs of pixel labels, provided by each segmentation results to be fused. Combined with a prior distribution, this energy-based Gibbs model also allows for definition of an interesting penalized maximum probabilistic rand estimator with which the fusion of simple, quickly estimated, segmentation results appears as an interesting alternative to complex segmentation models existing in the literature. This fusion framework has been successfully applied on the Berkeley image database. The experiments reported in this paper demonstrate that the proposed method is efficient in terms of visual evaluation and quantitative performance measures and performs well compared to the best existing state-of-the-art segmentation methods recently proposed in the literature.

A new fractional order derivative based active contour model for colon wall segmentation

NASA Astrophysics Data System (ADS)

Chen, Bo; Li, Lihong C.; Wang, Huafeng; Wei, Xinzhou; Huang, Shan; Chen, Wensheng; Liang, Zhengrong

2018-02-01

Segmentation of colon wall plays an important role in advancing computed tomographic colonography (CTC) toward a screening modality. Due to the low contrast of CT attenuation around colon wall, accurate segmentation of the boundary of both inner and outer wall is very challenging. In this paper, based on the geodesic active contour model, we develop a new model for colon wall segmentation. First, tagged materials in CTC images were automatically removed via a partial volume (PV) based electronic colon cleansing (ECC) strategy. We then present a new fractional order derivative based active contour model to segment the volumetric colon wall from the cleansed CTC images. In this model, the regionbased Chan-Vese model is incorporated as an energy term to the whole model so that not only edge/gradient information but also region/volume information is taken into account in the segmentation process. Furthermore, a fractional order differentiation derivative energy term is also developed in the new model to preserve the low frequency information and improve the noise immunity of the new segmentation model. The proposed colon wall segmentation approach was validated on 16 patient CTC scans. Experimental results indicate that the present scheme is very promising towards automatically segmenting colon wall, thus facilitating computer aided detection of initial colonic polyp candidates via CTC.

Treatment outcomes of ligature-induced recession in the dog model using guided tissue regeneration or coronally positioned flap procedures.

PubMed

Papageorgiou, Athanasios; Vouros, Ioannis; Konstantinidis, Antonios

2009-04-01

The aims of the study were: (1) to determine the quality of the hard and soft tissues formed in segments treated with coronally positioned flaps alone (CPF group) or combined with a polylactic acid resorbable membrane (guided tissue regeneration--GTR group) in wide type defects (canine teeth), and (2) to evaluate the behaviour of the newly regenerated tissues to an experimentally induced inflammation initiated by microbial plaque at the submarginal level in recession type defects (premolar teeth). The randomized block design was used in the study, with each dog receiving both treatments (GTR and CPF). Gingival recession defects were surgically created in the 2nd and 4th mandibular premolars and, after 10 weeks, also in the maxillary canines of three dogs. The defects in the premolar area were created earlier than the defects in the canine teeth so that both areas would be ready for biopsy at the same time. Two months after the creation of the defects the exposed roots in the control group of teeth were surgically covered with coronally positioned flaps only (CPF group), and in the test group of teeth a coronally positioned flap was used in combination with a resorbable membrane (GTR group). In the premolar teeth only, after a healing period of five months, cotton ligatures were placed intrasulcularly and these areas were left without plaque control for 10 weeks. Following this, biopsies were taken from the canines and the premolars in order to examine (1) the quality of the hard and soft tissues formed after five months of healing in the canine teeth and (2) the response of the newly formed tissues to microbial accumulation induced by the subgingival ligature placement. In the wide defects of the canine teeth, the use of the membrane produced a mean new attachment formation of 44%, while the repositioned flap technique produced 22% new attachment. The regeneration of bone was limited to the apical area for both techniques and amounted to 15% and 10%, respectively. In the narrow defects of the premolars both techniques produced comparable mean root coverage percentages. The inflammatory conditions created in the study led to a comparable loss of mean clinical attachment and an increase in tissue recession and the extent of the inflammatory process for both groups. The use of resorbable membranes for the treatment of wide recession type defects in the canine teeth (GTR group) produced significantly better clinical results, with higher mean root coverage and increased regenerative capacity of the periodontal tissues, compared with the coronally positioned flap technique (CPF group). Additionally, the regenerated tissues created after the use of both techniques in narrow recession defects (premolar teeth) demonstrated comparable resistance to the microbial accumulation conditions created.

Synthetic Generation of Myocardial Blood-Oxygen-Level-Dependent MRI Time Series via Structural Sparse Decomposition Modeling

PubMed Central

Rusu, Cristian; Morisi, Rita; Boschetto, Davide; Dharmakumar, Rohan; Tsaftaris, Sotirios A.

2014-01-01

This paper aims to identify approaches that generate appropriate synthetic data (computer generated) for Cardiac Phase-resolved Blood-Oxygen-Level-Dependent (CP–BOLD) MRI. CP–BOLD MRI is a new contrast agent- and stress-free approach for examining changes in myocardial oxygenation in response to coronary artery disease. However, since signal intensity changes are subtle, rapid visualization is not possible with the naked eye. Quantifying and visualizing the extent of disease relies on myocardial segmentation and registration to isolate the myocardium and establish temporal correspondences and ischemia detection algorithms to identify temporal differences in BOLD signal intensity patterns. If transmurality of the defect is of interest pixel-level analysis is necessary and thus a higher precision in registration is required. Such precision is currently not available affecting the design and performance of the ischemia detection algorithms. In this work, to enable algorithmic developments of ischemia detection irrespective to registration accuracy, we propose an approach that generates synthetic pixel-level myocardial time series. We do this by (a) modeling the temporal changes in BOLD signal intensity based on sparse multi-component dictionary learning, whereby segmentally derived myocardial time series are extracted from canine experimental data to learn the model; and (b) demonstrating the resemblance between real and synthetic time series for validation purposes. We envision that the proposed approach has the capacity to accelerate development of tools for ischemia detection while markedly reducing experimental costs so that cardiac BOLD MRI can be rapidly translated into the clinical arena for the noninvasive assessment of ischemic heart disease. PMID:24691119

Synthetic generation of myocardial blood-oxygen-level-dependent MRI time series via structural sparse decomposition modeling.

PubMed

Rusu, Cristian; Morisi, Rita; Boschetto, Davide; Dharmakumar, Rohan; Tsaftaris, Sotirios A

2014-07-01

This paper aims to identify approaches that generate appropriate synthetic data (computer generated) for cardiac phase-resolved blood-oxygen-level-dependent (CP-BOLD) MRI. CP-BOLD MRI is a new contrast agent- and stress-free approach for examining changes in myocardial oxygenation in response to coronary artery disease. However, since signal intensity changes are subtle, rapid visualization is not possible with the naked eye. Quantifying and visualizing the extent of disease relies on myocardial segmentation and registration to isolate the myocardium and establish temporal correspondences and ischemia detection algorithms to identify temporal differences in BOLD signal intensity patterns. If transmurality of the defect is of interest pixel-level analysis is necessary and thus a higher precision in registration is required. Such precision is currently not available affecting the design and performance of the ischemia detection algorithms. In this work, to enable algorithmic developments of ischemia detection irrespective to registration accuracy, we propose an approach that generates synthetic pixel-level myocardial time series. We do this by 1) modeling the temporal changes in BOLD signal intensity based on sparse multi-component dictionary learning, whereby segmentally derived myocardial time series are extracted from canine experimental data to learn the model; and 2) demonstrating the resemblance between real and synthetic time series for validation purposes. We envision that the proposed approach has the capacity to accelerate development of tools for ischemia detection while markedly reducing experimental costs so that cardiac BOLD MRI can be rapidly translated into the clinical arena for the noninvasive assessment of ischemic heart disease.

Novel Therapy for Bone Regeneration in Large Segmental Defects

DTIC Science & Technology

2015-10-01

mesenchymal stem cells (MSCs). The in- flammatory... mesenchymal stem cells and the wound healing process. Cells 2013;2:621-34. 17. Kumar A, Salimath BP, Stark GB, Finkenzeller G. 22 K.M. Davis et al.: Muscle...Gao X, Usas A, Tang Y, et al. A comparison of bone re- generation with human mesenchymal stem cells and mus- cle-derived stem cells and the

Novel Therapy for Bone Regeneration in Large Segmental Defects

DTIC Science & Technology

2017-12-01

on fracture healing. Clin Orthop Relat Res. 1998;355(Suppl):S230–8. 37. Pape HC, Giannoudis PV. Fat embolism and IM nailing. Injury. 2006;37(Suppl 4...BMP), thrombopoietin (TPO), therapy, fracture healing, bone regeneration, minipig, pig 16. SECURITY CLASSIFICATION OF: 17. LIMITATION OF ABSTRACT...2, TPO, or saline control. 2. KEYWORDS: Bone healing, bone morphogenetic protein (BMP), thrombopoietin (TPO), therapy, fracture healing, bone

Novel Therapy for Bone Regeneration in Large Segmental Defects

DTIC Science & Technology

2016-10-01

reamed and nonreamed intrame- dullary nailing on fracture healing. Clin Orthop Relat Res. 1998;355(Suppl):S230–8. 37. Pape HC, Giannoudis PV. Fat embolism ...extension period (Year 4). 15. SUBJECT TERMS Bone healing, bone morphogenetic protein (BMP), thrombopoietin (TPO), therapy, fracture healing, bone...Bone healing, bone morphogenetic protein (BMP), thrombopoietin (TPO), therapy, fracture healing, bone regeneration, minipig, pig 3. OVERALL PROJECT

Putting 3D modelling and 3D printing into practice: virtual surgery and preoperative planning to reconstruct complex post-traumatic skeletal deformities and defects

PubMed Central

Tetsworth, Kevin; Block, Steve; Glatt, Vaida

2017-01-01

3D printing technology has revolutionized and gradually transformed manufacturing across a broad spectrum of industries, including healthcare. Nowhere is this more apparent than in orthopaedics with many surgeons already incorporating aspects of 3D modelling and virtual procedures into their routine clinical practice. As a more extreme application, patient-specific 3D printed titanium truss cages represent a novel approach for managing the challenge of segmental bone defects. This review illustrates the potential indications of this innovative technique using 3D printed titanium truss cages in conjunction with the Masquelet technique. These implants are custom designed during a virtual surgical planning session with the combined input of an orthopaedic surgeon, an orthopaedic engineering professional and a biomedical design engineer. The ability to 3D model an identical replica of the original intact bone in a virtual procedure is of vital importance when attempting to precisely reconstruct normal anatomy during the actual procedure. Additionally, other important factors must be considered during the planning procedure, such as the three-dimensional configuration of the implant. Meticulous design is necessary to allow for successful implantation through the planned surgical exposure, while being aware of the constraints imposed by local anatomy and prior implants. This review will attempt to synthesize the current state of the art as well as discuss our personal experience using this promising technique. It will address implant design considerations including the mechanical, anatomical and functional aspects unique to each case. PMID:28220752

In vivo evaluation of a novel nanocomposite porous 3D scaffold in a rabbit model: histological analysis

PubMed Central

Mahmood, Saffanah Khuder; Razak, Intan-Shameha Abdul; Ghaji, Mustafa Saddam; Yusof, Loqman Mohamed; Mahmood, Zaid Khudhur; Rameli, Mohd Adha Bin P; Zakaria, Zuki Abu Bakar

2017-01-01

The healing of load-bearing segmental defects in long bones is a challenge due to the complex nature of the weight that affects the bone part and due to bending, shearing, axial, and torsional forces. An innovative porous 3D scaffolds implant of CaCO3 aragonite nanocomposite derived from cockle shell was advanced for substitute bone solely for load-bearing cases. The biomechanical characteristics of such materials were designed to withstand cortical bone strength. In promoting bone growth to the implant material, an ideal surface permeability was formed by means of freeze drying and by adding copolymers to the materials. The properties of coating and copolymers supplement were also assessed for bone-implant connection resolutions. To examine the properties of the material in advanced biological system, an experimental trial in an animal model was carried out. Critical sized defect of bone was created in rabbit’s radial bone to assess the material for a load-bearing application with a short and extended period assessment with histological evaluation of the incorporated implanted material to the bone of the host. Trials in animal models proved that the material has the capability of enduring load-bearing conditions for long-term use devoid of breaking or generating stress that affects the host bone. Histological examination further confirmed the improved integration of the implanted materials to the host bone with profound bone development into and also above the implanted scaffold, which was attained with negligible reaction of the tissues to a foreign implanted material. PMID:29238193

Putting 3D modelling and 3D printing into practice: virtual surgery and preoperative planning to reconstruct complex post-traumatic skeletal deformities and defects.

PubMed

Tetsworth, Kevin; Block, Steve; Glatt, Vaida

2017-01-01

3D printing technology has revolutionized and gradually transformed manufacturing across a broad spectrum of industries, including healthcare. Nowhere is this more apparent than in orthopaedics with many surgeons already incorporating aspects of 3D modelling and virtual procedures into their routine clinical practice. As a more extreme application, patient-specific 3D printed titanium truss cages represent a novel approach for managing the challenge of segmental bone defects. This review illustrates the potential indications of this innovative technique using 3D printed titanium truss cages in conjunction with the Masquelet technique. These implants are custom designed during a virtual surgical planning session with the combined input of an orthopaedic surgeon, an orthopaedic engineering professional and a biomedical design engineer. The ability to 3D model an identical replica of the original intact bone in a virtual procedure is of vital importance when attempting to precisely reconstruct normal anatomy during the actual procedure. Additionally, other important factors must be considered during the planning procedure, such as the three-dimensional configuration of the implant. Meticulous design is necessary to allow for successful implantation through the planned surgical exposure, while being aware of the constraints imposed by local anatomy and prior implants. This review will attempt to synthesize the current state of the art as well as discuss our personal experience using this promising technique. It will address implant design considerations including the mechanical, anatomical and functional aspects unique to each case. © The Authors, published by EDP Sciences, 2017.

The Dipole Segment Model for Axisymmetrical Elongated Asteroids

NASA Astrophysics Data System (ADS)

Zeng, Xiangyuan; Zhang, Yonglong; Yu, Yang; Liu, Xiangdong

2018-02-01

Various simplified models have been investigated as a way to understand the complex dynamical environment near irregular asteroids. A dipole segment model is explored in this paper, one that is composed of a massive straight segment and two point masses at the extremities of the segment. Given an explicitly simple form of the potential function that is associated with the dipole segment model, five topological cases are identified with different sets of system parameters. Locations, stabilities, and variation trends of the system equilibrium points are investigated in a parametric way. The exterior potential distribution of nearly axisymmetrical elongated asteroids is approximated by minimizing the acceleration error in a test zone. The acceleration error minimization process determines the parameters of the dipole segment. The near-Earth asteroid (8567) 1996 HW1 is chosen as an example to evaluate the effectiveness of the approximation method for the exterior potential distribution. The advantages of the dipole segment model over the classical dipole and the traditional segment are also discussed. Percent error of acceleration and the degree of approximation are illustrated by using the dipole segment model to approximate four more asteroids. The high efficiency of the simplified model over the polyhedron is clearly demonstrated by comparing the CPU time.

Lithospheric buckling and intra-arc stresses: A mechanism for arc segmentation

NASA Technical Reports Server (NTRS)

Nelson, Kerri L.

1989-01-01

Comparison of segment development of a number of arcs has shown that consistent relationships between segmentation, volcanism and variable stresses exists. Researchers successfully modeled these relationships using the conceptual model of lithospheric buckling of Yamaoka et al. (1986; 1987). Lithosphere buckling (deformation) provides the needed mechanism to explain segmentation phenomenon; offsets in volcanic fronts, distribution of calderas within segments, variable segment stresses and the chemical diversity seen between segment boundary and segment interior magmas.

Do 3D Printing Models Improve Anatomical Teaching About Hepatic Segments to Medical Students? A Randomized Controlled Study.

PubMed

Kong, Xiangxue; Nie, Lanying; Zhang, Huijian; Wang, Zhanglin; Ye, Qiang; Tang, Lei; Huang, Wenhua; Li, Jianyi

2016-08-01

It is a difficult and frustrating task for young surgeons and medical students to understand the anatomy of hepatic segments. We tried to develop an optimal 3D printing model of hepatic segments as a teaching aid to improve the teaching of hepatic segments. A fresh human cadaveric liver without hepatic disease was CT scanned. After 3D reconstruction, three types of 3D computer models of hepatic structures were designed and 3D printed as models of hepatic segments without parenchyma (type 1) and with transparent parenchyma (type 2), and hepatic ducts with segmental partitions (type 3). These models were evaluated by six experts using a five-point Likert scale. Ninety two medical freshmen were randomized into four groups to learn hepatic segments with the aid of the three types of models and traditional anatomic atlas (TAA). Their results of two quizzes were compared to evaluate the teaching effects of the four methods. Three types of models were successful produced which displayed the structures of hepatic segments. By experts' evaluation, type 3 model was better than type 1 and 2 models in anatomical condition, type 2 and 3 models were better than type 1 model in tactility, and type 3 model was better than type 1 model in overall satisfaction (P < 0.05). The first quiz revealed that type 1 model was better than type 2 model and TAA, while type 3 model was better than type 2 and TAA in teaching effects (P < 0.05). The second quiz found that type 1 model was better than TAA, while type 3 model was better than type 2 model and TAA regarding teaching effects (P < 0.05). Only TAA group had significant declines between two quizzes (P < 0.05). The model with segmental partitions proves to be optimal, because it can best improve anatomical teaching about hepatic segments.

Stepwise verification of bone regeneration using recombinant human bone morphogenetic protein-2 in rat fibula model

PubMed Central

2017-01-01

Objectives The purpose of this study was to introduce our three experiments on bone morphogenetic protein (BMP) and its carriers performed using the critical sized segmental defect (CSD) model in rat fibula and to investigate development of animal models and carriers for more effective bone regeneration. Materials and Methods For the experiments, 14, 16, and 24 rats with CSDs on both fibulae were used in Experiments 1, 2, and 3, respectively. BMP-2 with absorbable collagen sponge (ACS) (Experiments 1 and 2), autoclaved autogenous bone (AAB) and fibrin glue (FG) (Experiment 3), and xenogenic bone (Experiment 2) were used in the experimental groups. Radiographic and histomorphological evaluations were performed during the follow-up period of each experiment. Results Significant new bone formation was commonly observed in all experimental groups using BMP-2 compared to control and xenograft (porcine bone) groups. Although there was some difference based on BMP carrier, regenerated bone volume was typically reduced by remodeling after initially forming excessive bone. Conclusion BMP-2 demonstrates excellent ability for bone regeneration because of its osteoinductivity, but efficacy can be significantly different depending on its delivery system. ACS and FG showed relatively good bone regeneration capacity, satisfying the essential conditions of localization and release-control when used as BMP carriers. AAB could not provide release-control as a BMP carrier, but its space-maintenance role was remarkable. Carriers and scaffolds that can provide sufficient support to the BMP/carrier complex are necessary for large bone defects, and AAB is thought to be able to act as an effective scaffold. The CSD model of rat fibula is simple and useful for initial estimate of bone regeneration by agents including BMPs. PMID:29333367

CLASSICAL AREAS OF PHENOMENOLOGY: Study on the design and Zernike aberrations of a segmented mirror telescope

NASA Astrophysics Data System (ADS)

Jiang, Zhen-Yu; Li, Lin; Huang, Yi-Fan

2009-07-01

The segmented mirror telescope is widely used. The aberrations of segmented mirror systems are different from single mirror systems. This paper uses the Fourier optics theory to analyse the Zernike aberrations of segmented mirror systems. It concludes that the Zernike aberrations of segmented mirror systems obey the linearity theorem. The design of a segmented space telescope and segmented schemes are discussed, and its optical model is constructed. The computer simulation experiment is performed with this optical model to verify the suppositions. The experimental results confirm the correctness of the model.

Statistical shape (ASM) and appearance (AAM) models for the segmentation of the cerebellum in fetal ultrasound

NASA Astrophysics Data System (ADS)

Reyes López, Misael; Arámbula Cosío, Fernando

2017-11-01

The cerebellum is an important structure to determine the gestational age of the fetus, moreover most of the abnormalities it presents are related to growth disorders. In this work, we present the results of the segmentation of the fetal cerebellum applying statistical shape and appearance models. Both models were tested on ultrasound images of the fetal brain taken from 23 pregnant women, between 18 and 24 gestational weeks. The accuracy results obtained on 11 ultrasound images show a mean Hausdorff distance of 6.08 mm between the manual segmentation and the segmentation using active shape model, and a mean Hausdorff distance of 7.54 mm between the manual segmentation and the segmentation using active appearance model. The reported results demonstrate that the active shape model is more robust in the segmentation of the fetal cerebellum in ultrasound images.

Pigmentary glaucoma accompanied by Usher syndrome.

PubMed

Koucheki, Behrooz; Jalali, Kamran Hodjat

2012-08-01

To report a case of pigmentary glaucoma (PG) accompanied by Usher syndrome. Case report. The results were presented after standard ocular examination, visual field test, anterior segment and fundus photography, electroretinography, and otolaryngology consultation were conducted. Typical retinitis pigmentosa, flat electroretinography, congenital sensorineural hearing loss, high intraocular pressure, Krukenberg spindle, iris concavity, radial iris transillumination defect, severe pigment deposition on the trabecular meshwork, and glaucomatous optic nerve damage were indicative of PG accompanied by Usher syndrome. In some rare cases, PG may coexist with Usher syndrome. Common findings of Usher syndrome, including night blindness, impaired vision, visual field defects, and retinal changes may distract the clinician from considering the diagnosis of glaucoma. Such association should be borne in mind to make a timely diagnosis and treatment possible.

Step Cut Lengthening: A Technique for Treatment of Flexor Pollicis Longus Tendon Rupture.

PubMed

Chong, Chew-Wei; Chen, Shih-Heng

2018-04-01

Reconstruction of a tendon defect is a challenging task in hand surgery. Delayed repair of a ruptured flexor pollicis longus (FPL) tendon is often associated with tendon defect. Primary repair of the tendon is often not possible, particularly after debridement of the unhealthy segment of the tendon. As such, various surgical treatments have been described in the literature, including single-stage tendon grafting, 2-stage tendon grafting, flexor digitorum superficialis tendon transfer from ring finger, and interphalangeal joint arthrodesis. We describe step cut lengthening of FPL tendon for the reconstruction of FPL rupture. This is a single-stage reconstruction without the need for tendon grafting or tendon transfer. To our knowledge, no such technique has been previously described.

Sequential segmental classification of feline congenital heart disease.

PubMed

Scansen, Brian A; Schneider, Matthias; Bonagura, John D

2015-12-01

Feline congenital heart disease is less commonly encountered in veterinary medicine than acquired feline heart diseases such as cardiomyopathy. Understanding the wide spectrum of congenital cardiovascular disease demands a familiarity with a variety of lesions, occurring both in isolation and in combination, along with an appreciation of complex nomenclature and variable classification schemes. This review begins with an overview of congenital heart disease in the cat, including proposed etiologies and prevalence, examination approaches, and principles of therapy. Specific congenital defects are presented and organized by a sequential segmental classification with respect to their morphologic lesions. Highlights of diagnosis, treatment options, and prognosis are offered. It is hoped that this review will provide a framework for approaching congenital heart disease in the cat, and more broadly in other animal species based on the sequential segmental approach, which represents an adaptation of the common methodology used in children and adults with congenital heart disease. Copyright © 2015 Elsevier B.V. All rights reserved.

Production of Wnt4b by floor plate cells is essential for the segmental patterning of the vertebral column in medaka.

PubMed

Inohaya, Keiji; Takano, Yoshiro; Kudo, Akira

2010-06-01

The floor plate is a key organizer that controls the specification of neurons in the central nervous system. Here, we show a new role of the floor plate: segmental pattern formation of the vertebral column. Analysis of a spontaneous medaka mutant, fused centrum (fsc), which exhibits fused centra and the absence of the intervertebral ligaments, revealed that fsc encodes wnt4b, which was expressed exclusively in the floor plate. In fsc mutants, we found that wnt4b expression was completely lost in the floor plate and that abnormal conversion of the intervertebral ligament cells into osteoblasts appeared to cause a defect of the intervertebral ligaments. The establishment of the transgenic rescue lines and mosaic analyses allowed the conclusion to be drawn that production of wnt4b by floor plate cells is essential for the segmental patterning of the vertebral column. Our findings provide a novel perspective on the mechanism of vertebrate development.

Gene Therapy for MERTK-Associated Retinal Degenerations

PubMed Central

Matthes, Michael T.; Yang, Haidong; Hauswirth, William W.; Deng, Wen-Tao; Vollrath, Douglas

2016-01-01

MERTK-associated retinal degenerations are thought to have defects in phagocytosis of shed outer segment membranes by the retinal pigment epithelium (RPE), as do the rodent models of these diseases. We have subretinally injected an RPE-specific AAV2 vector, AAV2-VMD2-hMERTK, to determine whether this would provide long-term photoreceptor rescue in the RCS rat, which it did for up to 6.5 months, the longest time point examined. Moreover, we found phagosomes in the RPE in the rescued regions of RCS retinas soon after the onset of light. The same vector also had a major protective effect in Mertk-null mice, with a concomitant increase in ERG response amplitudes in the vector-injected eyes. These findings suggest that planned clinical trials with this vector will have a favorable outcome. PMID:26427450

A model to identify high crash road segments with the dynamic segmentation method.

PubMed

Boroujerdian, Amin Mirza; Saffarzadeh, Mahmoud; Yousefi, Hassan; Ghassemian, Hassan

2014-12-01

Currently, high social and economic costs in addition to physical and mental consequences put road safety among most important issues. This paper aims at presenting a novel approach, capable of identifying the location as well as the length of high crash road segments. It focuses on the location of accidents occurred along the road and their effective regions. In other words, due to applicability and budget limitations in improving safety of road segments, it is not possible to recognize all high crash road segments. Therefore, it is of utmost importance to identify high crash road segments and their real length to be able to prioritize the safety improvement in roads. In this paper, after evaluating deficiencies of the current road segmentation models, different kinds of errors caused by these methods are addressed. One of the main deficiencies of these models is that they can not identify the length of high crash road segments. In this paper, identifying the length of high crash road segments (corresponding to the arrangement of accidents along the road) is achieved by converting accident data to the road response signal of through traffic with a dynamic model based on the wavelet theory. The significant advantage of the presented method is multi-scale segmentation. In other words, this model identifies high crash road segments with different lengths and also it can recognize small segments within long segments. Applying the presented model into a real case for identifying 10-20 percent of high crash road segment showed an improvement of 25-38 percent in relative to the existing methods. Copyright © 2014 Elsevier Ltd. All rights reserved.

Finite element approximation of the fields of bulk and interfacial line defects

NASA Astrophysics Data System (ADS)

Zhang, Chiqun; Acharya, Amit; Puri, Saurabh

2018-05-01

A generalized disclination (g.disclination) theory (Acharya and Fressengeas, 2015) has been recently introduced that goes beyond treating standard translational and rotational Volterra defects in a continuously distributed defects approach; it is capable of treating the kinematics and dynamics of terminating lines of elastic strain and rotation discontinuities. In this work, a numerical method is developed to solve for the stress and distortion fields of g.disclination systems. Problems of small and finite deformation theory are considered. The fields of a single disclination, a single dislocation treated as a disclination dipole, a tilt grain boundary, a misfitting grain boundary with disconnections, a through twin boundary, a terminating twin boundary, a through grain boundary, a star disclination/penta-twin, a disclination loop (with twist and wedge segments), and a plate, a lenticular, and a needle inclusion are approximated. It is demonstrated that while the far-field topological identity of a dislocation of appropriate strength and a disclination-dipole plus a slip dislocation comprising a disconnection are the same, the latter microstructure is energetically favorable. This underscores the complementary importance of all of topology, geometry, and energetics in understanding defect mechanics. It is established that finite element approximations of fields of interfacial and bulk line defects can be achieved in a systematic and routine manner, thus contributing to the study of intricate defect microstructures in the scientific understanding and predictive design of materials. Our work also represents one systematic way of studying the interaction of (g.)disclinations and dislocations as topological defects, a subject of considerable subtlety and conceptual importance (Aharoni et al., 2017; Mermin, 1979).

Hybrid Signal Processing Technique to Improve the Defect Estimation in Ultrasonic Non-Destructive Testing of Composite Structures

PubMed Central

Raisutis, Renaldas; Samaitis, Vykintas

2017-01-01

This work proposes a novel hybrid signal processing technique to extract information on disbond-type defects from a single B-scan in the process of non-destructive testing (NDT) of glass fiber reinforced plastic (GFRP) material using ultrasonic guided waves (GW). The selected GFRP sample has been a segment of wind turbine blade, which possessed an aerodynamic shape. Two disbond type defects having diameters of 15 mm and 25 mm were artificially constructed on its trailing edge. The experiment has been performed using the low-frequency ultrasonic system developed at the Ultrasound Institute of Kaunas University of Technology and only one side of the sample was accessed. A special configuration of the transmitting and receiving transducers fixed on a movable panel with a separation distance of 50 mm was proposed for recording the ultrasonic guided wave signals at each one-millimeter step along the scanning distance up to 500 mm. Finally, the hybrid signal processing technique comprising the valuable features of the three most promising signal processing techniques: cross-correlation, wavelet transform, and Hilbert–Huang transform has been applied to the received signals for the extraction of defects information from a single B-scan image. The wavelet transform and cross-correlation techniques have been combined in order to extract the approximated size and location of the defects and measurements of time delays. Thereafter, Hilbert–Huang transform has been applied to the wavelet transformed signal to compare the variation of instantaneous frequencies and instantaneous amplitudes of the defect-free and defective signals. PMID:29232845

Road Asphalt Pavements Analyzed by Airborne Thermal Remote Sensing: Preliminary Results of the Venice Highway.

PubMed

Pascucci, Simone; Bassani, Cristiana; Palombo, Angelo; Poscolieri, Maurizio; Cavalli, Rosa

2008-02-22

This paper describes a fast procedure for evaluating asphalt pavement surface defects using airborne emissivity data. To develop this procedure, we used airborne multispectral emissivity data covering an urban test area close to Venice (Italy).For this study, we first identify and select the roads' asphalt pavements on Multispectral Infrared Visible Imaging Spectrometer (MIVIS) imagery using a segmentation procedure. Next, since in asphalt pavements the surface defects are strictly related to the decrease of oily components that cause an increase of the abundance of surfacing limestone, the diagnostic absorption emissivity peak at 11.2μm of the limestone was used for retrieving from MIVIS emissivity data the areas exhibiting defects on asphalt pavements surface.The results showed that MIVIS emissivity allows establishing a threshold that points out those asphalt road sites on which a check for a maintenance intervention is required. Therefore, this technique can supply local government authorities an efficient, rapid and repeatable road mapping procedure providing the location of the asphalt pavements to be checked.

Quantitative evaluation of hidden defects in cast iron components using ultrasound activated lock-in vibrothermography.

PubMed

Montanini, R; Freni, F; Rossi, G L

2012-09-01

This paper reports one of the first experimental results on the application of ultrasound activated lock-in vibrothermography for quantitative assessment of buried flaws in complex cast parts. The use of amplitude modulated ultrasonic heat generation allowed selective response of defective areas within the part, as the defect itself is turned into a local thermal wave emitter. Quantitative evaluation of hidden damages was accomplished by estimating independently both the area and the depth extension of the buried flaws, while x-ray 3D computed tomography was used as reference for sizing accuracy assessment. To retrieve flaw's area, a simple yet effective histogram-based phase image segmentation algorithm with automatic pixels classification has been developed. A clear correlation was found between the thermal (phase) signature measured by the infrared camera on the target surface and the actual mean cross-section area of the flaw. Due to the very fast cycle time (<30 s/part), the method could potentially be applied for 100% quality control of casting components.

Defect Facilitated Phonon Transport through Kinks in Boron Carbide Nanowires

DOE PAGES

Zhang, Qian; Cui, Zhiguang; Wei, Zhiyong; ...

2017-05-08

Nanowires of complex morphologies, such as kinked wires, have been recently synthesized and demonstrated for novel devices and applications. However, the effects of these morphologies on thermal transport have not been well studied. Through systematic experimental measurements, we show in this paper that single-crystalline, defect-free kinks in boron carbide nanowires can pose a thermal resistance up to ~30 times larger than that of a straight wire segment of equivalent length. Analysis suggests that this pronounced resistance can be attributed to the combined effects of backscattering of highly focused phonons and required mode conversion at the kink. Interestingly, it is alsomore » found that instead of posing resistance, structural defects in the kink can actually assist phonon transport through the kink and reduce its resistance. Finally, given the common kink-like wire morphology in nanoelectronic devices and required low thermal conductivity for thermoelectric devices, these findings have important implications in precise thermal management of electronic devices and thermoelectrics.« less

Defect Facilitated Phonon Transport through Kinks in Boron Carbide Nanowires

DOE Office of Scientific and Technical Information (OSTI.GOV)

Zhang, Qian; Cui, Zhiguang; Wei, Zhiyong

Nanowires of complex morphologies, such as kinked wires, have been recently synthesized and demonstrated for novel devices and applications. However, the effects of these morphologies on thermal transport have not been well studied. Through systematic experimental measurements, we show in this paper that single-crystalline, defect-free kinks in boron carbide nanowires can pose a thermal resistance up to ~30 times larger than that of a straight wire segment of equivalent length. Analysis suggests that this pronounced resistance can be attributed to the combined effects of backscattering of highly focused phonons and required mode conversion at the kink. Interestingly, it is alsomore » found that instead of posing resistance, structural defects in the kink can actually assist phonon transport through the kink and reduce its resistance. Finally, given the common kink-like wire morphology in nanoelectronic devices and required low thermal conductivity for thermoelectric devices, these findings have important implications in precise thermal management of electronic devices and thermoelectrics.« less

DYF-1 Is Required for Assembly of the Axoneme in Tetrahymena thermophila▿ †

PubMed Central

Dave, Drashti; Wloga, Dorota; Sharma, Neeraj; Gaertig, Jacek

2009-01-01

In most cilia, the axoneme can be subdivided into three segments: proximal (the transition zone), middle (with outer doublet microtubules), and distal (with singlet extensions of outer doublet microtubules). How the functionally distinct segments of the axoneme are assembled and maintained is not well understood. DYF-1 is a highly conserved ciliary protein containing tetratricopeptide repeats. In Caenorhabditis elegans, DYF-1 is specifically needed for assembly of the distal segment (G. Ou, O. E. Blacque, J. J. Snow, M. R. Leroux, and J. M. Scholey. Nature. 436:583-587, 2005). We show that Tetrahymena cells lacking an ortholog of DYF-1, Dyf1p, can assemble only extremely short axoneme remnants that have structural defects of diverse natures, including the absence of central pair and outer doublet microtubules and incomplete or absent B tubules on the outer microtubules. Thus, in Tetrahymena, DYF-1 is needed for either assembly or stability of the entire axoneme. Our observations support the conserved function for DYF-1 in axoneme assembly or stability but also show that the consequences of loss of DYF-1 for axoneme segments are organism specific. PMID:19581442

Biomechanical effects of hybrid stabilization on the risk of proximal adjacent-segment degeneration following lumbar spinal fusion using an interspinous device or a pedicle screw-based dynamic fixator.

PubMed

Lee, Chang-Hyun; Kim, Young Eun; Lee, Hak Joong; Kim, Dong Gyu; Kim, Chi Heon

2017-12-01

OBJECTIVE Pedicle screw-rod-based hybrid stabilization (PH) and interspinous device-based hybrid stabilization (IH) have been proposed to prevent adjacent-segment degeneration (ASD) and their effectiveness has been reported. However, a comparative study based on sound biomechanical proof has not yet been reported. The aim of this study was to compare the biomechanical effects of IH and PH on the transition and adjacent segments. METHODS A validated finite element model of the normal lumbosacral spine was used. Based on the normal model, a rigid fusion model was immobilized at the L4-5 level by a rigid fixator. The DIAM or NFlex model was added on the L3-4 segment of the fusion model to construct the IH and PH models, respectively. The developed models simulated 4 different loading directions using the hybrid loading protocol. RESULTS Compared with the intact case, fusion on L4-5 produced 18.8%, 9.3%, 11.7%, and 13.7% increments in motion at L3-4 under flexion, extension, lateral bending, and axial rotation, respectively. Additional instrumentation at L3-4 (transition segment) in hybrid models reduced motion changes at this level. The IH model showed 8.4%, -33.9%, 6.9%, and 2.0% change in motion at the segment, whereas the PH model showed -30.4%, -26.7%, -23.0%, and 12.9%. At L2-3 (adjacent segment), the PH model showed 14.3%, 3.4%, 15.0%, and 0.8% of motion increment compared with the motion in the IH model. Both hybrid models showed decreased intradiscal pressure (IDP) at the transition segment compared with the fusion model, but the pressure at L2-3 (adjacent segment) increased in all loading directions except under extension. CONCLUSIONS Both IH and PH models limited excessive motion and IDP at the transition segment compared with the fusion model. At the segment adjacent to the transition level, PH induced higher stress than IH model. Such differences may eventually influence the likelihood of ASD.

Turning Noise into Signal: Utilizing Impressed Pipeline Currents for EM Exploration

NASA Astrophysics Data System (ADS)

Lindau, Tobias; Becken, Michael

2017-04-01

Impressed Current Cathodic Protection (ICCP) systems are extensively used for the protection of central Europe's dense network of oil-, gas- and water pipelines against destruction by electrochemical corrosion. While ICCP systems usually provide protection by injecting a DC current into the pipeline, mandatory pipeline integrity surveys demand a periodical switching of the current. Consequently, the resulting time varying pipe currents induce secondary electric- and magnetic fields in the surrounding earth. While these fields are usually considered to be unwanted cultural noise in electromagnetic exploration, this work aims at utilizing the fields generated by the ICCP system for determining the electrical resistivity of the subsurface. The fundamental period of the switching cycles typically amounts to 15 seconds in Germany and thereby roughly corresponds to periods used in controlled source EM applications (CSEM). For detailed studies we chose an approximately 30km long pipeline segment near Herford, Germany as a test site. The segment is located close to the southern margin of the Lower Saxony Basin (LSB) and part of a larger gas pipeline composed of multiple segments. The current injected into the pipeline segment originates in a rectified 50Hz AC signal which is periodically switched on and off. In contrast to the usual dipole sources used in CSEM surveys, the current distribution along the pipeline is unknown and expected to be non-uniform due to coating defects that cause current to leak into the surrounding soil. However, an accurate current distribution is needed to model the fields generated by the pipeline source. We measured the magnetic fields at several locations above the pipeline and used Biot-Savarts-Law to estimate the currents decay function. The resulting frequency dependent current distribution shows a current decay away from the injection point as well as a frequency dependent phase shift which is increasing with distance from the injection point. Electric field data were recorded at 45 stations located in an area of about 60 square kilometers in the vicinity to the pipeline. Additionally, the injected source current was recorded directly at the injection point. Transfer functions between the local electric fields and the injected source current are estimated for frequencies ranging from 0.03Hz to 15Hz using robust time series processing techniques. The resulting transfer functions are inverted for a 3D conductivity model of the subsurface using an elaborate pipeline model. We interpret the model with regards to the local geologic setting, demonstrating the methods capabilities to image the subsurface.

Interactive Tooth Separation from Dental Model Using Segmentation Field

PubMed Central

2016-01-01

Tooth segmentation on dental model is an essential step of computer-aided-design systems for orthodontic virtual treatment planning. However, fast and accurate identifying cutting boundary to separate teeth from dental model still remains a challenge, due to various geometrical shapes of teeth, complex tooth arrangements, different dental model qualities, and varying degrees of crowding problems. Most segmentation approaches presented before are not able to achieve a balance between fine segmentation results and simple operating procedures with less time consumption. In this article, we present a novel, effective and efficient framework that achieves tooth segmentation based on a segmentation field, which is solved by a linear system defined by a discrete Laplace-Beltrami operator with Dirichlet boundary conditions. A set of contour lines are sampled from the smooth scalar field, and candidate cutting boundaries can be detected from concave regions with large variations of field data. The sensitivity to concave seams of the segmentation field facilitates effective tooth partition, as well as avoids obtaining appropriate curvature threshold value, which is unreliable in some case. Our tooth segmentation algorithm is robust to dental models with low quality, as well as is effective to dental models with different levels of crowding problems. The experiments, including segmentation tests of varying dental models with different complexity, experiments on dental meshes with different modeling resolutions and surface noises and comparison between our method and the morphologic skeleton segmentation method are conducted, thus demonstrating the effectiveness of our method. PMID:27532266

On the development of weighting factors for ballast ranking prioritization & development of the relationship and rate of defective segments based on volume of missing ballast

NASA Astrophysics Data System (ADS)

Cronin, John

This thesis explores the effects of missing ballast on track behavior and degradation. As ballast is an integral part of the track structure, the hypothesized effect of missing ballast is that defects will be more common which in turn leads to more derailments. In order to quantify the volume of missing ballast, remote sensing technologies were used to provide an accurate profile of the ballast. When the existing profile is compared to an idealized profile, the area of missing ballast can be computed. The area is then subdivided into zones which represent the area in which the ballast performs a key function in the track structure. These areas are then extrapolated into the volume of missing ballast for each zone based on the distance between collected profiles. In order to emphasize the key functions that the zones previously created perform, weighting factors were developed based on common risk-increasing hazards, such as curves and heavy axle loads, which are commonly found on railways. These weighting factors are applied to the specified zones' missing ballast volume when such a hazard exists in that segment of track. Another set of weighting factors were developed to represent the increased risk, or preference for lower risk, for operational factors such as the transport of hazardous materials or for being a key route. Through these weighting factors, ballast replenishment can be prioritized to focus on the areas that pose a higher risk of derailments and their associated costs. For the special cases where the risk or aversion to risk comes from what is being transported, such as the case with hazardous materials or passengers, an economic risk assessment was completed in order to quantify the risk associated with their transport. This economic risk assessment looks at the increased costs associated with incidents that occur and how they compare to incidents which do not directly involve the special cargos. In order to provide support for the use of the previously developed weightings as well as to quantify the actual impact that missing ballast has on the rate of geometry defects, analyses which quantified the risk of missing ballast were performed. In addition to quantifying the rate of defects, analyses were performed which looked at the impact associated with curved track, how the location of missing ballast impacts the rate of geometry defects and how the combination of the two compared with the previous analyses. Through this research, the relationship between the volume of missing ballast and ballast-related defects has been identified and quantified. This relationship is positive for the aggregate of all ballast-related defects but does not always exist for individual defects which occasionally have unique behavior. For the non-ballast defects, a relationship between missing ballast and their rate of occurrence did not always appear to exist. The impact of curves was apparent, showing that the rate of defects was either similar to or exceeded the rate of defects for tangent track. For the analyses which looked at the location of ballast in crib or shoulder, the results were quite similar to the previous analyses. The development, application and improvements of a risk-based ballast maintenance prioritization system provides a relatively low-cost and effective method to improve the operational safety for all railroads.

Segmenting Continuous Motions with Hidden Semi-markov Models and Gaussian Processes

PubMed Central

Nakamura, Tomoaki; Nagai, Takayuki; Mochihashi, Daichi; Kobayashi, Ichiro; Asoh, Hideki; Kaneko, Masahide

2017-01-01

Humans divide perceived continuous information into segments to facilitate recognition. For example, humans can segment speech waves into recognizable morphemes. Analogously, continuous motions are segmented into recognizable unit actions. People can divide continuous information into segments without using explicit segment points. This capacity for unsupervised segmentation is also useful for robots, because it enables them to flexibly learn languages, gestures, and actions. In this paper, we propose a Gaussian process-hidden semi-Markov model (GP-HSMM) that can divide continuous time series data into segments in an unsupervised manner. Our proposed method consists of a generative model based on the hidden semi-Markov model (HSMM), the emission distributions of which are Gaussian processes (GPs). Continuous time series data is generated by connecting segments generated by the GP. Segmentation can be achieved by using forward filtering-backward sampling to estimate the model's parameters, including the lengths and classes of the segments. In an experiment using the CMU motion capture dataset, we tested GP-HSMM with motion capture data containing simple exercise motions; the results of this experiment showed that the proposed GP-HSMM was comparable with other methods. We also conducted an experiment using karate motion capture data, which is more complex than exercise motion capture data; in this experiment, the segmentation accuracy of GP-HSMM was 0.92, which outperformed other methods. PMID:29311889

Allogeneic adipose-derived stem cells regenerate bone in a critical-sized ulna segmental defect

PubMed Central

Wen, Congji; Yan, Hai; Fu, Shibo; Qian, Yunliang

2016-01-01

Adipose-derived stem cells (ASCs) with multilineage potential can be induced into osteoblasts, adipocytes and chondrocytes. ASCs as seed cell are widely used in the field of tissue engineering, but most studies either use autologous cells as the source or an immunodeficient animal as the host. In our present study, we explored the feasibility of applying allogeneic ASCs and demineralized bone matrix (DBM) scaffolds for repairing tubular bone defects without using immunosuppressive therapy. Allogeneic ASCs were expanded and seeded on DBM scaffolds and induced to differentiate along the osteogenic lineage. Eight Sprague–Dawley (SD) rats were used in this study and bilateral critical-sized defects (8 mm) of the ulna were created and divided into two groups: with ASC-DBM constructs or DBM alone. The systemic immune response and the extent of bone healing were evaluated post-operatively. Twenty-four weeks after implantation, digital radiography (DR) testing showed that new bones had formed in the experimental group. By contrast, no bone tissue formation was observed in the control group. This study demonstrated that allogeneic ASCs could promote bone regeneration and repair tubular bone defects combined with DBM by histologically typical bone without systemic immune response PMID:25819682

Automatic detection system of shaft part surface defect based on machine vision

NASA Astrophysics Data System (ADS)

Jiang, Lixing; Sun, Kuoyuan; Zhao, Fulai; Hao, Xiangyang

2015-05-01

Surface physical damage detection is an important part of the shaft parts quality inspection and the traditional detecting methods are mostly human eye identification which has many disadvantages such as low efficiency, bad reliability. In order to improve the automation level of the quality detection of shaft parts and establish its relevant industry quality standard, a machine vision inspection system connected with MCU was designed to realize the surface detection of shaft parts. The system adopt the monochrome line-scan digital camera and use the dark-field and forward illumination technology to acquire images with high contrast; the images were segmented to Bi-value images through maximum between-cluster variance method after image filtering and image enhancing algorithms; then the mainly contours were extracted based on the evaluation criterion of the aspect ratio and the area; then calculate the coordinates of the centre of gravity of defects area, namely locating point coordinates; At last, location of the defects area were marked by the coding pen communicated with MCU. Experiment show that no defect was omitted and false alarm error rate was lower than 5%, which showed that the designed system met the demand of shaft part on-line real-time detection.

Using Predictability for Lexical Segmentation.

PubMed

Çöltekin, Çağrı

2017-09-01

This study investigates a strategy based on predictability of consecutive sub-lexical units in learning to segment a continuous speech stream into lexical units using computational modeling and simulations. Lexical segmentation is one of the early challenges during language acquisition, and it has been studied extensively through psycholinguistic experiments as well as computational methods. However, despite strong empirical evidence, the explicit use of predictability of basic sub-lexical units in models of segmentation is underexplored. This paper presents an incremental computational model of lexical segmentation for exploring the usefulness of predictability for lexical segmentation. We show that the predictability cue is a strong cue for segmentation. Contrary to earlier reports in the literature, the strategy yields state-of-the-art segmentation performance with an incremental computational model that uses only this particular cue in a cognitively plausible setting. The paper also reports an in-depth analysis of the model, investigating the conditions affecting the usefulness of the strategy. Copyright © 2016 Cognitive Science Society, Inc.

Homologous interference mediated by defective interfering influenza virus derived from a temperature-sensitive mutant of influenza virus.

PubMed Central

Nayak, D P; Tobita, K; Janda, J M; Davis, A R; De, B K

1978-01-01

A temperature-sensitive group II mutant of influenza virus, ts-52, with a presumed defect in viral RNA synthesis, readily produced von Magnus-type defective interfering virus (DI virus) when passed serially (four times) at high multiplicity in MDBK cells. The defective virus (ts-52 DI virus) had a high hemagglutinin and a low infectivity titer, and strongly interfered with the replication of standard infectious viruses (both ts-52 and wild-type ts+) in co-infected cells. Progeny virus particles produced by co-infection of DI virus and infectious virus were also defective and also had low infectivity, high hemagglutinating activity, and a strong interfering property. Infectious viruses ts+ and ts-52 were indistinguishable from ts-52 DI viruses by sucrose velocity or density gradient analysis. Additionally, these viruses all possessed similar morphology. However, when the RNA of DI viruses was analyzed by use of polyacrylamide gels containing 6 M urea, there was a reduction in the amount of large RNA species (V1 to V4), and a number of new smaller RNA species (D1 to D6) with molecular weights ranging from 2.9 X 10(5) to 1.05 X 10(5) appeared. Since these smaller RNA species (D1 to D6) were absent in some clones of infectious viruses, but were consistently associated with DI viruses and increased during undiluted passages and during co-infection of ts-52 with DI virus, they appeared to be a characteristic of DI viruses. Additionally, the UV target size of interfering activity and infectivity of DI virus indicated that interfering activity was 40 times more resistant to UV irradiation than was infectivity, further implicating small RNA molecules in interference. Our data suggest that the loss of infectivity observed among DI viruses may be due to nonspecific loss of a viral RNA segment(s), and the interfering property of DI viruses may be due to interfering RNA segments (DIRNA, D1 to D6). ts-52 DI virus interfered with the replication of standard virus (ts+) at both permissive (34 degrees C) and nonpermissive temperatures. The infectivity of the progeny virus was reduced to 0.2% for ts+ and 0.05% for ts-52 virus without a reduction in hemagglutinin titer. Interference was dependent on the concentration of DI virus. A particle ratio of 1 between DI virus (0.001 PFU/cell) and infectious virus (1.0 PFU/cell) produced a maximal amount of interference. Infectious virus yield was reduced 99.9% without any reduction of the yield of DI viruses Interference was also dependent on the time of addition of DI virus. Interference was most effective within the first 3 h of infection by infectious virus, indicating interference with an early function during viral replication. Images PMID:702654

Words in Puddles of Sound: Modelling Psycholinguistic Effects in Speech Segmentation

ERIC Educational Resources Information Center

Monaghan, Padraic; Christiansen, Morten H.

2010-01-01

There are numerous models of how speech segmentation may proceed in infants acquiring their first language. We present a framework for considering the relative merits and limitations of these various approaches. We then present a model of speech segmentation that aims to reveal important sources of information for speech segmentation, and to…

T2 relaxation time measurements are limited in monitoring progression, once advanced cartilage defects at the knee occur

PubMed Central

Jungmann, P.M.; Kraus, M.S.; Nardo, L.; Liebl, H.; Alizai, H.; Joseph, G.B.; Liu, F.; Lynch, J.; McCulloch, C.E.; Nevitt, M.C.; Link, T.M.

2014-01-01

Purpose To study the natural evolution of cartilage T2 relaxation times in knees with various extents of morphological cartilage abnormalities, assessed with 3T MRI from the Osteoarthritis Initiative. Materials and Methods Right knee MRIs of 245, 45–60 year old individuals without radiographic OA were included. Cartilage was segmented and T2 maps were generated in five compartments (patella, medial and lateral femoral condyle, medial and lateral tibia) at baseline and two-year follow-up. We examined the association of T2 values and two-year change of T2 values with various Whole-Organ MR Imaging Scores (WORMS). Statistical analysis was performed with ANOVA and Students t-tests. Results Higher baseline T2 was associated with more severe cartilage defects at baseline and subsequent cartilage loss (P<0.001). However, longitudinal T2 change was inversely associated with both baseline (P=0.038) and follow-up (P=0.002) severity of cartilage defects. Knees that developed new cartilage defects had smaller increases in T2 than subjects without defects (P=0.045). Individuals with higher baseline T2 showed smaller T2 increases over time (P<0.001). Conclusion An inverse correlation of longitudinal T2 changes versus baseline T2 values and morphological cartilage abnormalities suggests that once morphological cartilage defects occur, T2 values may be limited for evaluating further cartilage degradation. PMID:24038491

A Minimal Path Searching Approach for Active Shape Model (ASM)-based Segmentation of the Lung.

PubMed

Guo, Shengwen; Fei, Baowei

2009-03-27

We are developing a minimal path searching method for active shape model (ASM)-based segmentation for detection of lung boundaries on digital radiographs. With the conventional ASM method, the position and shape parameters of the model points are iteratively refined and the target points are updated by the least Mahalanobis distance criterion. We propose an improved searching strategy that extends the searching points in a fan-shape region instead of along the normal direction. A minimal path (MP) deformable model is applied to drive the searching procedure. A statistical shape prior model is incorporated into the segmentation. In order to keep the smoothness of the shape, a smooth constraint is employed to the deformable model. To quantitatively assess the ASM-MP segmentation, we compare the automatic segmentation with manual segmentation for 72 lung digitized radiographs. The distance error between the ASM-MP and manual segmentation is 1.75 ± 0.33 pixels, while the error is 1.99 ± 0.45 pixels for the ASM. Our results demonstrate that our ASM-MP method can accurately segment the lung on digital radiographs.

A minimal path searching approach for active shape model (ASM)-based segmentation of the lung

NASA Astrophysics Data System (ADS)

Guo, Shengwen; Fei, Baowei

2009-02-01

We are developing a minimal path searching method for active shape model (ASM)-based segmentation for detection of lung boundaries on digital radiographs. With the conventional ASM method, the position and shape parameters of the model points are iteratively refined and the target points are updated by the least Mahalanobis distance criterion. We propose an improved searching strategy that extends the searching points in a fan-shape region instead of along the normal direction. A minimal path (MP) deformable model is applied to drive the searching procedure. A statistical shape prior model is incorporated into the segmentation. In order to keep the smoothness of the shape, a smooth constraint is employed to the deformable model. To quantitatively assess the ASM-MP segmentation, we compare the automatic segmentation with manual segmentation for 72 lung digitized radiographs. The distance error between the ASM-MP and manual segmentation is 1.75 +/- 0.33 pixels, while the error is 1.99 +/- 0.45 pixels for the ASM. Our results demonstrate that our ASM-MP method can accurately segment the lung on digital radiographs.

A Minimal Path Searching Approach for Active Shape Model (ASM)-based Segmentation of the Lung

PubMed Central

Guo, Shengwen; Fei, Baowei

2013-01-01

We are developing a minimal path searching method for active shape model (ASM)-based segmentation for detection of lung boundaries on digital radiographs. With the conventional ASM method, the position and shape parameters of the model points are iteratively refined and the target points are updated by the least Mahalanobis distance criterion. We propose an improved searching strategy that extends the searching points in a fan-shape region instead of along the normal direction. A minimal path (MP) deformable model is applied to drive the searching procedure. A statistical shape prior model is incorporated into the segmentation. In order to keep the smoothness of the shape, a smooth constraint is employed to the deformable model. To quantitatively assess the ASM-MP segmentation, we compare the automatic segmentation with manual segmentation for 72 lung digitized radiographs. The distance error between the ASM-MP and manual segmentation is 1.75 ± 0.33 pixels, while the error is 1.99 ± 0.45 pixels for the ASM. Our results demonstrate that our ASM-MP method can accurately segment the lung on digital radiographs. PMID:24386531

Adaptive Mutations in Influenza A/California/07/2009 Enhance Polymerase Activity and Infectious Virion Production.

PubMed

Slaine, Patrick D; MacRae, Cara; Kleer, Mariel; Lamoureux, Emily; McAlpine, Sarah; Warhuus, Michelle; Comeau, André M; McCormick, Craig; Hatchette, Todd; Khaperskyy, Denys A

2018-05-18

Mice are not natural hosts for influenza A viruses (IAVs), but they are useful models for studying antiviral immune responses and pathogenesis. Serial passage of IAV in mice invariably causes the emergence of adaptive mutations and increased virulence. Here, we report the adaptation of IAV reference strain A/California/07/2009(H1N1) (also known as CA/07) in outbred Swiss Webster mice. Serial passage led to increased virulence and lung titers, and dissemination of the virus to brains. We adapted a deep-sequencing protocol to identify and enumerate adaptive mutations across all genome segments. Among mutations that emerged during mouse-adaptation, we focused on amino acid substitutions in polymerase subunits: polymerase basic-1 (PB1) T156A and F740L and polymerase acidic (PA) E349G. These mutations were evaluated singly and in combination in minigenome replicon assays, which revealed that PA E349G increased polymerase activity. By selectively engineering three PB1 and PA mutations into the parental CA/07 strain, we demonstrated that these mutations in polymerase subunits decreased the production of defective viral genome segments with internal deletions and dramatically increased the release of infectious virions from mouse cells. Together, these findings increase our understanding of the contribution of polymerase subunits to successful host adaptation.

Development of a Novel Segmental Bone Defect Construct

DTIC Science & Technology

2017-10-01

differentiation, and biological activity of both primary synoviocytes and bone marrow derived connective tissue progenitor cells. During the majority of...halted activity on the project from the dates of 31 May 2016 to 13 July 2017. However, the project is on schedule with the current, revised project...supervised all project activities and participated in the preparation of the manuscript that was produced during this reporting period. Name: Dr

Novel Therapy for Bone Regeneration in Large Segmental Defects

DTIC Science & Technology

2014-10-01

for post-operative animal care. The time, effort, and even drugs required ( pain management) for post-operative management of minipigs has been...substantially larger than was anticipated. The veterinarian is still finalizing the post-operative pain management protocol as with each surgery he is...assessment/management. By Monday morning the veterinarian usually reduces the pain scoring and pain medications to twice a day. This of course does

Novel Therapy for Bone Regeneration in Large Segmental Defects

DTIC Science & Technology

2016-10-01

Giannoudis PV. Fat embolism and IM nailing. Injury. 2006;37(Suppl 4):S1–2. 38. Wenda K, Ritter G, Degreif J, Rudigier J. Pathogenesis of pul- monary... fracture healing, bone regeneration, minipig, pig 16. SECURITY CLASSIFICATION OF: 17. LIMITATION OF ABSTRACT 18. NUMBER OF PAGES 19a. NAME OF...saline control. 2. KEYWORDS: Bone healing, bone morphogenetic protein (BMP), thrombopoietin (TPO), therapy, fracture healing, bone regeneration, minipig

Ready to Use Tissue Construct for Military Bone & Cartilage Trauma

DTIC Science & Technology

2014-10-01

during nail introduction and reaming. In the present study, we examined the load - bearing capacity and optimal internal fixation of a bone/poly-ε...segmental defect, (a) axial loading via ball bearing , (b) torsional loading via square clamp allowing axial displacement, (c) three-point bending of tibia...knee joints by simulating loads seen during ambulation and knee range of motion. Our central hypothesis is that an anatomically and

Characterization of Electrically Active Defects in Si Using CCD Image Sensors

DTIC Science & Technology

1978-02-01

63 35 Dislocation Segments in CCD Imager . . . . . . . . . . . . . 64 36 422 Reflection Topograph of Dislocation Loop ir... Loops . . . . . 3 39 422 Reflection Topograph of Scratch on CCD Imager, . . . 69 40 Dark Current Display of a CCD Imager with 32 ms integration Time...made of each slice using the elon -asoorbio aold developer described in Appendix D. The inagers were then thinned using the procedure at Appendix taor

A hybrid intelligence approach to artifact recognition in digital publishing

NASA Astrophysics Data System (ADS)

Vega-Riveros, J. Fernando; Santos Villalobos, Hector J.

2006-02-01

The system presented integrates rule-based and case-based reasoning for artifact recognition in Digital Publishing. In Variable Data Printing (VDP) human proofing could result prohibitive since a job could contain millions of different instances that may contain two types of artifacts: 1) evident defects, like a text overflow or overlapping 2) style-dependent artifacts, subtle defects that show as inconsistencies with regard to the original job design. We designed a Knowledge-Based Artifact Recognition tool for document segmentation, layout understanding, artifact detection, and document design quality assessment. Document evaluation is constrained by reference to one instance of the VDP job proofed by a human expert against the remaining instances. Fundamental rules of document design are used in the rule-based component for document segmentation and layout understanding. Ambiguities in the design principles not covered by the rule-based system are analyzed by case-based reasoning, using the Nearest Neighbor Algorithm, where features from previous jobs are used to detect artifacts and inconsistencies within the document layout. We used a subset of XSL-FO and assembled a set of 44 document samples. The system detected all the job layout changes, while obtaining an overall average accuracy of 84.56%, with the highest accuracy of 92.82%, for overlapping and the lowest, 66.7%, for the lack-of-white-space.

Locally adaptive MR intensity models and MRF-based segmentation of multiple sclerosis lesions

NASA Astrophysics Data System (ADS)

Galimzianova, Alfiia; Lesjak, Žiga; Likar, Boštjan; Pernuš, Franjo; Špiclin, Žiga

2015-03-01

Neuroimaging biomarkers are an important paraclinical tool used to characterize a number of neurological diseases, however, their extraction requires accurate and reliable segmentation of normal and pathological brain structures. For MR images of healthy brains the intensity models of normal-appearing brain tissue (NABT) in combination with Markov random field (MRF) models are known to give reliable and smooth NABT segmentation. However, the presence of pathology, MR intensity bias and natural tissue-dependent intensity variability altogether represent difficult challenges for a reliable estimation of NABT intensity model based on MR images. In this paper, we propose a novel method for segmentation of normal and pathological structures in brain MR images of multiple sclerosis (MS) patients that is based on locally-adaptive NABT model, a robust method for the estimation of model parameters and a MRF-based segmentation framework. Experiments on multi-sequence brain MR images of 27 MS patients show that, compared to whole-brain model and compared to the widely used Expectation-Maximization Segmentation (EMS) method, the locally-adaptive NABT model increases the accuracy of MS lesion segmentation.

Brain MR image segmentation using NAMS in pseudo-color.

PubMed

Li, Hua; Chen, Chuanbo; Fang, Shaohong; Zhao, Shengrong

2017-12-01

Image segmentation plays a crucial role in various biomedical applications. In general, the segmentation of brain Magnetic Resonance (MR) images is mainly used to represent the image with several homogeneous regions instead of pixels for surgical analyzing and planning. This paper proposes a new approach for segmenting MR brain images by using pseudo-color based segmentation with Non-symmetry and Anti-packing Model with Squares (NAMS). First of all, the NAMS model is presented. The model can represent the image with sub-patterns to keep the image content and largely reduce the data redundancy. Second, the key idea is proposed that convert the original gray-scale brain MR image into a pseudo-colored image and then segment the pseudo-colored image with NAMS model. The pseudo-colored image can enhance the color contrast in different tissues in brain MR images, which can improve the precision of segmentation as well as directly visual perceptional distinction. Experimental results indicate that compared with other brain MR image segmentation methods, the proposed NAMS based pseudo-color segmentation method performs more excellent in not only segmenting precisely but also saving storage.

Evaluation of articulation simulation system using artificial maxillectomy models.

PubMed

Elbashti, M E; Hattori, M; Sumita, Y I; Taniguchi, H

2015-09-01

Acoustic evaluation is valuable for guiding the treatment of maxillofacial defects and determining the effectiveness of rehabilitation with an obturator prosthesis. Model simulations are important in terms of pre-surgical planning and pre- and post-operative speech function. This study aimed to evaluate the acoustic characteristics of voice generated by an articulation simulation system using a vocal tract model with or without artificial maxillectomy defects. More specifically, we aimed to establish a speech simulation system for maxillectomy defect models that both surgeons and maxillofacial prosthodontists can use in guiding treatment planning. Artificially simulated maxillectomy defects were prepared according to Aramany's classification (Classes I-VI) in a three-dimensional vocal tract plaster model of a subject uttering the vowel /a/. Formant and nasalance acoustic data were analysed using Computerized Speech Lab and the Nasometer, respectively. Formants and nasalance of simulated /a/ sounds were successfully detected and analysed. Values of Formants 1 and 2 for the non-defect model were 675.43 and 976.64 Hz, respectively. Median values of Formants 1 and 2 for the defect models were 634.36 and 1026.84 Hz, respectively. Nasalance was 11% in the non-defect model, whereas median nasalance was 28% in the defect models. The results suggest that an articulation simulation system can be used to help surgeons and maxillofacial prosthodontists to plan post-surgical defects that will be facilitate maxillofacial rehabilitation. © 2015 John Wiley & Sons Ltd.

Stem cell derived endochondral cartilage stimulates bone healing by tissue transformation

PubMed Central

Bahney, Chelsea S; Hu, Diane P; Taylor, Aaron J; Ferro, Federico; Britz, Hayley M; Hallgrimsson, Benedikt; Johnstone, Brian; Miclau, Theodore; Marcucio, Ralph S

2016-01-01

Although bone has great capacity for repair, there are a number of clinical situations (fracture non-unions, spinal fusions, revision arthroplasty, segmental defects) in which auto- or allografts augment bone regeneration. Critical failures associated with current grafting treatments include osteonecrosis and limited integration between graft and host tissue. We speculated that the underlying problem with current bone grafting techniques is that they promote bone regeneration through direct osteogenesis. We hypothesized that using cartilage to promote endochondral bone regeneration would leverage normal developmental and repair sequences to produce a well-vascularized regenerate that integrates with the host tissue. In this study we use a translational murine model of a segmental tibia defect to test the clinical utility of bone regeneration from a cartilage graft. We further test the mechanism by which cartilage promotes bone regeneration using in vivo lineage tracing and in vitro culture experiments. Our data show that cartilage grafts support regeneration of a vascularized and integrated bone tissue in vivo, and subsequently propose a translational tissue engineering platform using chondrogenesis of MSCs. Interestingly, lineage tracing experiments show the regenerate was graft derived, suggesting transformation of the chondrocytes into bone. In vitro culture data shows that cartilage explants mineralize with the addition of BMP or by exposure to HUVEC conditioned medium, indicating that endothelial cells directly promote ossification. This study provides pre-clinical data for endochondral bone repair that has potential to significantly improve patient outcomes in a variety of musculoskeletal diseases and injuries. Further, in contrast to the dogmatic view that hypertrophic chondrocytes undergo apoptosis prior to bone formation, our data suggest cartilage can transform into bone by activating the pluripotent transcription factor Oct4A. Together these data represent a paradigm shift describing the mechanism of endochondral bone repair and open the door for novel regenerative strategies based on improved biology. PMID:24259230

DOE Office of Scientific and Technical Information (OSTI.GOV)

Upadhyaya, Mihir; Jindal, Vibhu; Basavalingappa, Adarsh

The availability of defect-free masks is considered to be a critical issue for enabling extreme ultraviolet lithography (EUVL) as the next generation technology. Since completely defect-free masks will be hard to achieve, it is essential to have a good understanding of the printability of the native EUV mask defects. In this work, we performed a systematic study of native mask defects to understand the defect printability caused by them. The multilayer growth over native substrate mask blank defects was correlated to the multilayer growth over regular-shaped defects having similar profiles in terms of their width and height. To model themore » multilayer growth over the defects, a novel level-set multilayer growth model was used that took into account the tool deposition conditions of the Veeco Nexus ion beam deposition tool. The same tool was used for performing the actual deposition of the multilayer stack over the characterized native defects, thus ensuring a fair comparison between the actual multilayer growth over native defects, and modeled multilayer growth over regular-shaped defects. Further, the printability of the characterized native defects was studied with the SEMATECH-Berkeley Actinic Inspection Tool (AIT), an EUV mask-imaging microscope at Lawrence Berkeley National Laboratory (LBNL). Printability of the modeled regular-shaped defects, which were propagated up the multilayer stack using level-set growth model was studied using defect printability simulations implementing the waveguide algorithm. Good comparison was observed between AIT and the simulation results, thus demonstrating that multilayer growth over a defect is primarily a function of a defect’s width and height, irrespective of its shape. This would allow us to predict printability of the arbitrarily-shaped native EUV mask defects in a systematic and robust manner.« less

HIRSCHSPRUNG'S DISEASE—The Clinical Differentiation and Treatment of Children with Hirschsprung's Disease and Pseudo-Hirschsprung's Disease

PubMed Central

Ravitch, Mark M.

1958-01-01

Hirschsprung's disease is marked by constipation from the time of birth, with the development, if uncorrected, of a protuberant abdomen and flared costal margins. The rectal ampulla is empty and the abdomen is filled with fecal masses. Pain is not prominent. Flatus is passed in large amounts. Encopresis does not occur. Barium enema shows the characteristic narrowed distal rectal segment and biopsy of the rectum shows absence of the ganglion cells of the myenteric plexus. Treatment is operative resection of the distal narrow segment and a primary anastomosis. Hirschsprung's disease may be mimicked in children with: 1. Psychogenic constipation—pseudo-Hirschsprung's disease. Unlike Hirschsprung's disease, symptoms do not appear at birth, encopresis is common, and the barium enema shows no narrow distal segment. 2. Mental retardation and cerebral defect. 3. Corrected imperforate anus—on the basis of stenosis, imperfect innervation or poor habit training. 4. Cretinism—with severe constipation and intestinal dilatation perhaps the presenting symptoms. Treatment of these four groups of children with severe constipation not due to Hirschsprung's disease is: For Group 1, open discussion with parent and child. Assumption by the physician of full control of the details of treatment, and relegation of parent to the role of the physician's agent in following the prescribed regimen. For Group 2, an enema regimen. Whereas fairly rapid restoration (and then persistence) of normal bowel habit can be expected in Group 1, the basic defects in Group 2 may require indefinite continuation of treatment. For Group 3, regular enema regimen, in the less severe cases—one identical with that used in Group 1, and dilatation of strictures or anoplasty. In Group 4, thyroid hormone therapy relieves the constipation of hypothyroidism and causes reversion of radiographic changes in the colon and rectum. PMID:13561108

Bloom DNA Helicase Facilitates Homologous Recombination between Diverged Homologous Sequences*

PubMed Central

Kikuchi, Koji; Abdel-Aziz, H. Ismail; Taniguchi, Yoshihito; Yamazoe, Mitsuyoshi; Takeda, Shunichi; Hirota, Kouji

2009-01-01

Bloom syndrome caused by inactivation of the Bloom DNA helicase (Blm) is characterized by increases in the level of sister chromatid exchange, homologous recombination (HR) associated with cross-over. It is therefore believed that Blm works as an anti-recombinase. Meanwhile, in Drosophila, DmBlm is required specifically to promote the synthesis-dependent strand anneal (SDSA), a type of HR not associating with cross-over. However, conservation of Blm function in SDSA through higher eukaryotes has been a matter of debate. Here, we demonstrate the function of Blm in SDSA type HR in chicken DT40 B lymphocyte line, where Ig gene conversion diversifies the immunoglobulin V gene through intragenic HR between diverged homologous segments. This reaction is initiated by the activation-induced cytidine deaminase enzyme-mediated uracil formation at the V gene, which in turn converts into abasic site, presumably leading to a single strand gap. Ig gene conversion frequency was drastically reduced in BLM−/− cells. In addition, BLM−/− cells used limited donor segments harboring higher identity compared with other segments in Ig gene conversion event, suggesting that Blm can promote HR between diverged sequences. To further understand the role of Blm in HR between diverged homologous sequences, we measured the frequency of gene targeting induced by an I-SceI-endonuclease-mediated double-strand break. BLM−/− cells showed a severer defect in the gene targeting frequency as the number of heterologous sequences increased at the double-strand break site. Conversely, the overexpression of Blm, even an ATPase-defective mutant, strongly stimulated gene targeting. In summary, Blm promotes HR between diverged sequences through a novel ATPase-independent mechanism. PMID:19661064

Borderline Glenoid Bone Defect in Anterior Shoulder Instability: Latarjet Procedure Versus Bankart Repair.

PubMed

Jeon, Yoon Sang; Jeong, Ho Yeon; Lee, Dong Ki; Rhee, Yong Girl

2018-06-01

The optimal procedure for anterior shoulder instability with a borderline (15%-20%) bone defect on the anterior rim of the glenoid is still controversial. To compare the clinical outcome and recurrence rate between the arthroscopic Bankart repair and Latarjet procedure among patients with recurrent anterior shoulder instability and a borderline glenoid bone defect. Cohort study; Level of evidence, 3. The authors retrospectively reviewed cases of arthroscopic Bankart repair and the Latarjet procedure for recurrent anterior shoulder instability with a borderline (15%-20%) glenoid bone defect. Enrollment comprised 149 patients (Bankart group, n = 118; Latarjet group, n = 31). The mean follow-up and age at operation were 28.9 ± 7.3 months (range, 24-73 months) and 26 ± 5 years (range, 16-46 years), respectively. Rowe and UCLA (University of California, Los Angeles) shoulder scores significantly improved from 42.0 ± 14.3 and 22.9 ± 3.2 preoperatively to 90.9 ± 15.4 and 32.5 ± 3.3 postoperatively in the Bankart group ( P < .001) and from 41.0 ± 17.9 and 22.3 ± 3.4 to 91.1 ± 16.1 and 32.3 ± 3.4 in the Latarjet group ( P < .001), respectively. There were no significant between-group differences in Rowe ( P = .920) or UCLA ( P = .715) scores at the final follow-up. Mean postoperative loss of motion during forward flexion, external rotation in abduction, and internal rotation to the posterior was 3.0° ± 6.2°, 11.6° ± 10.2°, and 0.6 spinal segment in the Bankart group and 3.7° ± 9.8°, 10.3° ± 12.8°, and 0.9 spinal segment in the Latarjet group, respectively. These differences were not significant. However, the loss of external rotation at the side was significantly greater in the Bankart group (13.3° ± 12.9°) than in the Latarjet group (7.3° ± 18.1°, P = .034). The overall recurrence rate was significantly higher in the Bankart group (22.9%) than in the Latarjet group (6.5%), ( P = .040). The Latarjet procedure and arthroscopic Bankart repair both provided satisfactory clinical outcome scores and pain relief for anterior shoulder instability with a borderline glenoid bone defect. However, the Latarjet procedure resulted in significantly lower recurrences and less external rotation limitation than the arthroscopic Bankart repair. Therefore, the Latarjet procedure could be a more reliable surgical option in anterior recurrent instability with a borderline glenoid bone defect.

Model for transport and reaction of defects and carriers within displacement cascades in gallium arsenide

DOE Office of Scientific and Technical Information (OSTI.GOV)

Wampler, William R., E-mail: wrwampl@sandia.gov; Myers, Samuel M.

A model is presented for recombination of charge carriers at evolving displacement damage in gallium arsenide, which includes clustering of the defects in atomic displacement cascades produced by neutron or ion irradiation. The carrier recombination model is based on an atomistic description of capture and emission of carriers by the defects with time evolution resulting from the migration and reaction of the defects. The physics and equations on which the model is based are presented, along with the details of the numerical methods used for their solution. The model uses a continuum description of diffusion, field-drift and reaction of carriers,more » and defects within a representative spherically symmetric cluster of defects. The initial radial defect profiles within the cluster were determined through pair-correlation-function analysis of the spatial distribution of defects obtained from the binary-collision code MARLOWE, using recoil energies for fission neutrons. Properties of the defects are discussed and values for their parameters are given, many of which were obtained from density functional theory. The model provides a basis for predicting the transient response of III-V heterojunction bipolar transistors to displacement damage from energetic particle irradiation.« less

Novel osteoinductive photo-cross-linkable chitosan-lactide-fibrinogen hydrogels enhance bone regeneration in critical size segmental bone defects

PubMed Central

Kim, Sungwoo; Bedigrew, Katherine; Guda, Teja; Maloney, William J.; Park, Sangwon; Wenke, Joseph C.; Yang, Yunzhi Peter

2014-01-01

The purpose of this study was to develop and characterize a novel photo-cross-linkable chitosan-lactide-fibrinogen (CLF) hydrogel and evaluate the efficacy of bone morphogenetic protein-2 (BMP-2) containing CLF hydrogel for osteogenesis in vitro and in vivo. We synthesized the CLF hydrogels and characterized their chemical structure, degradation rate, compressive modulus, and in vitro BMP-2 release kinetics. We evaluated bioactivities of the BMP-2 containing CLF hydrogels (0, 50, 100, and 500 ng/ml) in vitro using W-20-17 preosteoblast mouse bone marrow stromal cells and C2C12 mouse myoblast cells. The effect of BMP-2 containing CLF gels (0, 0.5, 1, 2, and 5μg) on bone formation was evaluated using rat critical size segmental bone defects for 4 weeks. FTIR spectra and SEM images showed chemical and structural changes by addition of fibrinogen into chitosan-lactide copolymer. Incorporation of fibrinogen molecules significantly increased compressive modulus of the hydrogels. In vitro BMP-2 release study showed initial burst releases from the CLF hydrogels followed by sustained releases, regardless of the concentration of the BMP-2 over 4 weeks. Cells in all groups were viable in the presence of the hydrogels regardless of BMP-2 doses, indicating non-cytotoxicity of hydrogels. Alkaline phosphate activity and mineralization of cells exhibited dose dependence on BMP-2 containing CLF hydrogels. Radiographs, microcomputed tomography, and histology confirmed that the BMP-2 containing CLF hydrogels prompted neo-osteogenesis and accelerated healing of the defects in a dose-dependent manner. Thus the CLF hydrogel is a promising delivery system of growth factors for bone regeneration. PMID:25174669

A first principles calculation and statistical mechanics modeling of defects in Al-H system

NASA Astrophysics Data System (ADS)

Ji, Min; Wang, Cai-Zhuang; Ho, Kai-Ming

2007-03-01

The behavior of defects and hydrogen in Al was investigated by first principles calculations and statistical mechanics modeling. The formation energy of different defects in Al+H system such as Al vacancy, H in institution and multiple H in Al vacancy were calculated by first principles method. Defect concentration in thermodynamical equilibrium was studied by total free energy calculation including configuration entropy and defect-defect interaction from low concentration limit to hydride limit. In our grand canonical ensemble model, hydrogen chemical potential under different environment plays an important role in determing the defect concentration and properties in Al-H system.

A proposed defect tracking model for classifying the inserted defect reports to enhance software quality control.

PubMed

Sultan, Torky; Khedr, Ayman E; Sayed, Mostafa

2013-01-01

NONE DECLARED Defect tracking systems play an important role in the software development organizations as they can store historical information about defects. There are many research in defect tracking models and systems to enhance their capabilities to be more specifically tracking, and were adopted with new technology. Furthermore, there are different studies in classifying bugs in a step by step method to have clear perception and applicable method in detecting such bugs. This paper shows a new proposed defect tracking model for the purpose of classifying the inserted defects reports in a step by step method for more enhancement of the software quality.

Sparse intervertebral fence composition for 3D cervical vertebra segmentation

NASA Astrophysics Data System (ADS)

Liu, Xinxin; Yang, Jian; Song, Shuang; Cong, Weijian; Jiao, Peifeng; Song, Hong; Ai, Danni; Jiang, Yurong; Wang, Yongtian

2018-06-01

Statistical shape models are capable of extracting shape prior information, and are usually utilized to assist the task of segmentation of medical images. However, such models require large training datasets in the case of multi-object structures, and it also is difficult to achieve satisfactory results for complex shapes. This study proposed a novel statistical model for cervical vertebra segmentation, called sparse intervertebral fence composition (SiFC), which can reconstruct the boundary between adjacent vertebrae by modeling intervertebral fences. The complex shape of the cervical spine is replaced by a simple intervertebral fence, which considerably reduces the difficulty of cervical segmentation. The final segmentation results are obtained by using a 3D active contour deformation model without shape constraint, which substantially enhances the recognition capability of the proposed method for objects with complex shapes. The proposed segmentation framework is tested on a dataset with CT images from 20 patients. A quantitative comparison against corresponding reference vertebral segmentation yields an overall mean absolute surface distance of 0.70 mm and a dice similarity index of 95.47% for cervical vertebral segmentation. The experimental results show that the SiFC method achieves competitive cervical vertebral segmentation performances, and completely eliminates inter-process overlap.

Ilizarov bone transport versus fibular graft for reconstruction of tibial bone defects in children.

PubMed

Abdelkhalek, Mostafa; El-Alfy, Barakat; Ali, Ayman M

2016-11-01

The aim of this study was to compare the results of treatment of segmental tibial defects in the pediatric age group using an Ilizarov external fixator versus a nonvascularized fibular bone graft. This study included 24 patients (age range from 5.5 to 15 years) with tibial bone defects: 13 patients were treated with bone transport (BT) and 11 patients were treated with a nonvascularized fibular graft (FG). The outcome parameters were bone results (union, deformity, infection, leg-length discrepancy) and functional results: external fixation index and external fixation time. In group A (BT), one patient developed refracture at the regenerate site, whereas, in group B (FG), after removal of the external fixator, one of the FGs developed a stress fracture. The external fixator time in group A was 10.7 months (range 8-14.5) versus 7.8 months (range 4-11.5 months) in group B (FG). In group A (BT), one patient had a limb-length discrepancy (LLD), whereas, in group B (FG), three patients had LLD. The functional and bone results of the Ilizarov BT technique were excellent in 23.1 and 30.8%, good in 38.5 and 46.2, fair in 30.8 and 15.4, and poor in 7.6 and 7.6%, respectively. The poor functional result was related to the poor bone result because of prolonged external fixator time resulting in significant pain, limited ankle motion, whereas the functional and bone results of fibular grafting were excellent in 9.1 and 18.2%, good in 63.6 and 45.5%, fair in 18.2 and 27.2%, and poor in 9.1 and 9.1%, respectively. Segmental tibial defects can be effectively treated with both methods. The FG method provides satisfactory results, with early removal of the external fixator. However, it had a limitation in patients with severe infection and those with LLD. Also, it requires a long duration of limb bracing until adequate hypertrophy of the graft. The Ilizarov method has the advantages of early weight bearing, treatment of postinfection bone defect in a one-stage surgery, and the possibility to treat the associated LLD. However, it has a long external fixation time.

Multiscale crystal defect dynamics: A coarse-grained lattice defect model based on crystal microstructure

NASA Astrophysics Data System (ADS)

Lyu, Dandan; Li, Shaofan

2017-10-01

Crystal defects have microstructure, and this microstructure should be related to the microstructure of the original crystal. Hence each type of crystals may have similar defects due to the same failure mechanism originated from the same microstructure, if they are under the same loading conditions. In this work, we propose a multiscale crystal defect dynamics (MCDD) model that models defects by considering its intrinsic microstructure derived from the microstructure or material genome of the original perfect crystal. The main novelties of present work are: (1) the discrete exterior calculus and algebraic topology theory are used to construct a scale-up (coarse-grained) dual lattice model for crystal defects, which may represent all possible defect modes inside a crystal; (2) a higher order Cauchy-Born rule (up to the fourth order) is adopted to construct atomistic-informed constitutive relations for various defect process zones, and (3) an hierarchical strain gradient theory based finite element formulation is developed to support an hierarchical multiscale cohesive (process) zone model for various defects in a unified formulation. The efficiency of MCDD computational algorithm allows us to simulate dynamic defect evolution at large scale while taking into account atomistic interaction. The MCDD model has been validated by comparing of the results of MCDD simulations with that of molecular dynamics (MD) in the cases of nanoindentation and uniaxial tension. Numerical simulations have shown that MCDD model can predict dislocation nucleation induced instability and inelastic deformation, and thus it may provide an alternative solution to study crystal plasticity.

Analysis and design of segment control system in segmented primary mirror

NASA Astrophysics Data System (ADS)

Yu, Wenhao; Li, Bin; Chen, Mo; Xian, Hao

2017-10-01

Segmented primary mirror will be adopted widely in giant telescopes in future, such as TMT, E-ELT and GMT. High-performance control technology of the segmented primary mirror is one of the difficult technologies for telescopes using segmented primary mirror. The control of each segment is the basis of control system in segmented mirror. Correcting the tilt and tip of single segment is the main work of this paper which is divided into two parts. Firstly, harmonic response done in finite element model of single segment matches the Bode diagram of a two-order system whose natural frequency is 45 hertz and damping ratio is 0.005. Secondly, a control system model is established, and speed feedback is introduced in control loop to suppress resonance point gain and increase the open-loop bandwidth, up to 30Hz or even higher. Corresponding controller is designed based on the control system model described above.

Rabbit Calvarial Defect Model for Customized 3D-Printed Bone Grafts.

PubMed

Lee, Kang-Gon; Lee, Kang-Sik; Kang, Yu-Jeoung; Hwang, Jong-Hyun; Lee, Se-Hwan; Park, Sang-Hyug; Park, Yongdoo; Cho, Young-Sam; Lee, Bu-Kyu

2018-05-01

Bone graft materials are commonly used to regenerate various bone defects, but their application is often limited because of the complex defect shape in various clinical conditions. Hence, customized bone grafts using three-dimensional (3D) printing techniques have been developed. However, conventional simple bone defect models are limited for evaluating the benefits and manufacturing accuracy of 3D-printed customized bone grafts. Thus, the aim of the present study was to develop a complex-shaped bone defect model. We designed an 8-shaped bony defect that consists of two simple circles attached to the rabbit calvarium. To determine the critical-sized defect (CSD) of the 8-shaped defects, 5.6- and 7-mm-diameter trephine burs were tested, and the 7-mm-diameter bur could successfully create a CSD, which was easily reproducible on the rabbit calvarium. The rate of new bone formation was 28.65% ± 8.63% at 16 weeks following creation of the defect. To confirm its efficacy for clinical use, the 8-shaped defect was created on a rabbit calvarium and 3D computed tomography (CT) was performed. A stereolithography file was produced using the CT data, and a 3D-printed polycaprolactone graft was fabricated. Using our 8-shaped defect model, we were able to modify the tolerances of the bone graft and calvarial defect to fabricate a more precise bone graft. Customized characteristics of the bone graft were then used to improve the accuracy of the bone graft. In addition, we confirmed the fitting ability of the 3D-printed graft during implantation of the graft. Our 8-shaped defect model on the rabbit calvarium using a 7.0-mm trephine bur may be a useful CSD model for evaluating 3D-printed graft materials.

Multiclassifier fusion in human brain MR segmentation: modelling convergence.

PubMed

Heckemann, Rolf A; Hajnal, Joseph V; Aljabar, Paul; Rueckert, Daniel; Hammers, Alexander

2006-01-01

Segmentations of MR images of the human brain can be generated by propagating an existing atlas label volume to the target image. By fusing multiple propagated label volumes, the segmentation can be improved. We developed a model that predicts the improvement of labelling accuracy and precision based on the number of segmentations used as input. Using a cross-validation study on brain image data as well as numerical simulations, we verified the model. Fit parameters of this model are potential indicators of the quality of a given label propagation method or the consistency of the input segmentations used.

Markov models of genome segmentation

NASA Astrophysics Data System (ADS)

Thakur, Vivek; Azad, Rajeev K.; Ramaswamy, Ram

2007-01-01

We introduce Markov models for segmentation of symbolic sequences, extending a segmentation procedure based on the Jensen-Shannon divergence that has been introduced earlier. Higher-order Markov models are more sensitive to the details of local patterns and in application to genome analysis, this makes it possible to segment a sequence at positions that are biologically meaningful. We show the advantage of higher-order Markov-model-based segmentation procedures in detecting compositional inhomogeneity in chimeric DNA sequences constructed from genomes of diverse species, and in application to the E. coli K12 genome, boundaries of genomic islands, cryptic prophages, and horizontally acquired regions are accurately identified.

A perspective of gene therapy in the glaucomas.

PubMed

Kaufman, P L; Jia, W W; Tan, J; Chen, Z; Gabelt, B T; Booth, V; Tufaro, F; Cynader, M

1999-06-01

Gene therapy in the anterior and posterior segment tissues may have the potential to favorably influence aqueous hydrodynamics and retinal ganglion cell biology, thereby preventing, delaying, or minimizing glaucomatous damage to the optic nerve. We demonstrated the feasibility of using a herpes viral vector (ribonucleotide reductase defective HSV-1, hrR3) to deliver the lacZ reporter gene to living cat and rat eyes. Cats received injections into the anterior chamber and rats into the vitreous cavity. In cats, lacZ expression was detectable at 1 to 2 days in the anterior outer portion of the ciliary muscle and the lining of the intertrabecular spaces of the corneoscleral and uveal meshwork. Rat eyes showed lacZ expression in the retinal pigment epithelium and photoreceptor outer segments 2 days after injection.

Effect of noise on defect chaos in a reaction-diffusion model.

PubMed

Wang, Hongli; Ouyang, Qi

2005-06-01

The influence of noise on defect chaos due to breakup of spiral waves through Doppler and Eckhaus instabilities is investigated numerically with a modified Fitzhugh-Nagumo model. By numerical simulations we show that the noise can drastically enhance the creation and annihilation rates of topological defects. The noise-free probability distribution function for defects in this model is found not to fit with the previously reported squared-Poisson distribution. Under the influence of noise, the distributions are flattened, and can fit with the squared-Poisson or the modified-Poisson distribution. The defect lifetime and diffusive property of defects under the influence of noise are also checked in this model.

Testing and analysis of internal hardwood log defect prediction models

Treesearch

R. Edward Thomas

2011-01-01

The severity and location of internal defects determine the quality and value of lumber sawn from hardwood logs. Models have been developed to predict the size and position of internal defects based on external defect indicator measurements. These models were shown to predict approximately 80% of all internal knots based on external knot indicators. However, the size...

Defect detection and classification of machined surfaces under multiple illuminant directions

NASA Astrophysics Data System (ADS)

Liao, Yi; Weng, Xin; Swonger, C. W.; Ni, Jun

2010-08-01

Continuous improvement of product quality is crucial to the successful and competitive automotive manufacturing industry in the 21st century. The presence of surface porosity located on flat machined surfaces such as cylinder heads/blocks and transmission cases may allow leaks of coolant, oil, or combustion gas between critical mating surfaces, thus causing damage to the engine or transmission. Therefore 100% inline inspection plays an important role for improving product quality. Although the techniques of image processing and machine vision have been applied to machined surface inspection and well improved in the past 20 years, in today's automotive industry, surface porosity inspection is still done by skilled humans, which is costly, tedious, time consuming and not capable of reliably detecting small defects. In our study, an automated defect detection and classification system for flat machined surfaces has been designed and constructed. In this paper, the importance of the illuminant direction in a machine vision system was first emphasized and then the surface defect inspection system under multiple directional illuminations was designed and constructed. After that, image processing algorithms were developed to realize 5 types of 2D or 3D surface defects (pore, 2D blemish, residue dirt, scratch, and gouge) detection and classification. The steps of image processing include: (1) image acquisition and contrast enhancement (2) defect segmentation and feature extraction (3) defect classification. An artificial machined surface and an actual automotive part: cylinder head surface were tested and, as a result, microscopic surface defects can be accurately detected and assigned to a surface defect class. The cycle time of this system can be sufficiently fast that implementation of 100% inline inspection is feasible. The field of view of this system is 150mm×225mm and the surfaces larger than the field of view can be stitched together in software.

Multivariate statistical model for 3D image segmentation with application to medical images.

PubMed

John, Nigel M; Kabuka, Mansur R; Ibrahim, Mohamed O

2003-12-01

In this article we describe a statistical model that was developed to segment brain magnetic resonance images. The statistical segmentation algorithm was applied after a pre-processing stage involving the use of a 3D anisotropic filter along with histogram equalization techniques. The segmentation algorithm makes use of prior knowledge and a probability-based multivariate model designed to semi-automate the process of segmentation. The algorithm was applied to images obtained from the Center for Morphometric Analysis at Massachusetts General Hospital as part of the Internet Brain Segmentation Repository (IBSR). The developed algorithm showed improved accuracy over the k-means, adaptive Maximum Apriori Probability (MAP), biased MAP, and other algorithms. Experimental results showing the segmentation and the results of comparisons with other algorithms are provided. Results are based on an overlap criterion against expertly segmented images from the IBSR. The algorithm produced average results of approximately 80% overlap with the expertly segmented images (compared with 85% for manual segmentation and 55% for other algorithms).

Successful fifth metatarsal bulk autograft reconstruction of thermal necrosis post intramedullary fixation.

PubMed

Veljkovic, Andrea; Le, Vu; Escudero, Mario; Salat, Peter; Wing, Kevin; Penner, Murray; Younger, Alastair

2018-03-21

Reamed intramedullary (IM) screw fixation for proximal fifth metatarsal fractures is technically challenging with potentially devastating complications if basic principles are not followed. A case of an iatrogenic fourth-degree burn after elective reamed IM screw fixation of a proximal fifth metatarsal fracture in a high-level athlete is reported. The case was complicated by postoperative osteomyelitis with third-degree soft-tissue defect. This was successfully treated with staged autologous bone graft reconstruction, tendon reconstruction, and local bi-pedicle flap coverage. The patient returned to competitive-level sports, avoiding the need for fifth ray amputation. Critical points of the IM screw technique and definitive reconstruction are discussed. Bulk autograft reconstruction is a safe and effective alternative to ray amputation in segmental defects of the fifth metatarsal.Level of evidence V.

Object-oriented approach to the automatic segmentation of bones from pediatric hand radiographs

NASA Astrophysics Data System (ADS)

Shim, Hyeonjoon; Liu, Brent J.; Taira, Ricky K.; Hall, Theodore R.

1997-04-01

The purpose of this paper is to develop a robust and accurate method that automatically segments phalangeal and epiphyseal bones from digital pediatric hand radiographs exhibiting various stages of growth. The development of this system draws principles from object-oriented design, model- guided analysis, and feedback control. A system architecture called 'the object segmentation machine' was implemented incorporating these design philosophies. The system is aided by a knowledge base where all model contours and other information such as age, race, and sex, are stored. These models include object structure models, shape models, 1-D wrist profiles, and gray level histogram models. Shape analysis is performed first by using an arc-length orientation transform to break down a given contour into elementary segments and curves. Then an interpretation tree is used as an inference engine to map known model contour segments to data contour segments obtained from the transform. Spatial and anatomical relationships among contour segments work as constraints from shape model. These constraints aid in generating a list of candidate matches. The candidate match with the highest confidence is chosen to be the current intermediate result. Verification of intermediate results are perform by a feedback control loop.

[Medical image segmentation based on the minimum variation snake model].

PubMed

Zhou, Changxiong; Yu, Shenglin

2007-02-01

It is difficult for traditional parametric active contour (Snake) model to deal with automatic segmentation of weak edge medical image. After analyzing snake and geometric active contour model, a minimum variation snake model was proposed and successfully applied to weak edge medical image segmentation. This proposed model replaces constant force in the balloon snake model by variable force incorporating foreground and background two regions information. It drives curve to evolve with the criterion of the minimum variation of foreground and background two regions. Experiments and results have proved that the proposed model is robust to initial contours placements and can segment weak edge medical image automatically. Besides, the testing for segmentation on the noise medical image filtered by curvature flow filter, which preserves edge features, shows a significant effect.

Key Questions in Building Defect Prediction Models in Practice

NASA Astrophysics Data System (ADS)

Ramler, Rudolf; Wolfmaier, Klaus; Stauder, Erwin; Kossak, Felix; Natschläger, Thomas

The information about which modules of a future version of a software system are defect-prone is a valuable planning aid for quality managers and testers. Defect prediction promises to indicate these defect-prone modules. However, constructing effective defect prediction models in an industrial setting involves a number of key questions. In this paper we discuss ten key questions identified in context of establishing defect prediction in a large software development project. Seven consecutive versions of the software system have been used to construct and validate defect prediction models for system test planning. Furthermore, the paper presents initial empirical results from the studied project and, by this means, contributes answers to the identified questions.

A Proposed Defect Tracking Model for Classifying the Inserted Defect Reports to Enhance Software Quality Control

PubMed Central

Khedr, Ayman E.; Sayed, Mostafa

2013-01-01

CONFLICT OF INTEREST: NONE DECLARED Defect tracking systems play an important role in the software development organizations as they can store historical information about defects. There are many research in defect tracking models and systems to enhance their capabilities to be more specifically tracking, and were adopted with new technology. Furthermore, there are different studies in classifying bugs in a step by step method to have clear perception and applicable method in detecting such bugs. This paper shows a new proposed defect tracking model for the purpose of classifying the inserted defects reports in a step by step method for more enhancement of the software quality. PMID:24039334

Theoretical investigations on the structures and properties of CL-20/TNT cocrystal and its defective models by molecular dynamics simulation.

PubMed

Hang, Gui-Yun; Yu, Wen-Li; Wang, Tao; Wang, Jin-Tao

2018-06-09

"Perfect" and defective models of CL-20/TNT cocrystal explosive were established. Molecular dynamics methods were introduced to determine the structures and predict the comprehensive performances, including stabilities, sensitivity, energy density and mechanical properties, of the different models. The influences of crystal defects on the properties of these explosives were investigated and evaluated. The results show that, compared with the "perfect" model, the rigidity and toughness of defective models are decreased, while the ductility, tenacity and plastic properties are enhanced. The binding energies, interaction energy of the trigger bond, and the cohesive energy density of defective crystals declined, thus implying that stabilities are weakened, the explosive molecule is activated, trigger bond strength is diminished and safety is worsened. Detonation performance showed that, owing to the influence of crystal defects, the density is lessened, detonation pressure and detonation velocity are also declined, i.e., the power of defective explosive is decreased. In a word, the crystal defects may have a favorable effect on the mechanical properties, but have a disadvantageous influence on sensitivity, stability and energy density of CL-20/TNT cocrystal explosive. The results could provide theoretical guidance and practical instructions to estimate the properties of defective crystal models.

Whole vertebral bone segmentation method with a statistical intensity-shape model based approach

NASA Astrophysics Data System (ADS)

Hanaoka, Shouhei; Fritscher, Karl; Schuler, Benedikt; Masutani, Yoshitaka; Hayashi, Naoto; Ohtomo, Kuni; Schubert, Rainer

2011-03-01

An automatic segmentation algorithm for the vertebrae in human body CT images is presented. Especially we focused on constructing and utilizing 4 different statistical intensity-shape combined models for the cervical, upper / lower thoracic and lumbar vertebrae, respectively. For this purpose, two previously reported methods were combined: a deformable model-based initial segmentation method and a statistical shape-intensity model-based precise segmentation method. The former is used as a pre-processing to detect the position and orientation of each vertebra, which determines the initial condition for the latter precise segmentation method. The precise segmentation method needs prior knowledge on both the intensities and the shapes of the objects. After PCA analysis of such shape-intensity expressions obtained from training image sets, vertebrae were parametrically modeled as a linear combination of the principal component vectors. The segmentation of each target vertebra was performed as fitting of this parametric model to the target image by maximum a posteriori estimation, combined with the geodesic active contour method. In the experimental result by using 10 cases, the initial segmentation was successful in 6 cases and only partially failed in 4 cases (2 in the cervical area and 2 in the lumbo-sacral). In the precise segmentation, the mean error distances were 2.078, 1.416, 0.777, 0.939 mm for cervical, upper and lower thoracic, lumbar spines, respectively. In conclusion, our automatic segmentation algorithm for the vertebrae in human body CT images showed a fair performance for cervical, thoracic and lumbar vertebrae.

Automated MRI segmentation for individualized modeling of current flow in the human head.

PubMed

Huang, Yu; Dmochowski, Jacek P; Su, Yuzhuo; Datta, Abhishek; Rorden, Christopher; Parra, Lucas C

2013-12-01

High-definition transcranial direct current stimulation (HD-tDCS) and high-density electroencephalography require accurate models of current flow for precise targeting and current source reconstruction. At a minimum, such modeling must capture the idiosyncratic anatomy of the brain, cerebrospinal fluid (CSF) and skull for each individual subject. Currently, the process to build such high-resolution individualized models from structural magnetic resonance images requires labor-intensive manual segmentation, even when utilizing available automated segmentation tools. Also, accurate placement of many high-density electrodes on an individual scalp is a tedious procedure. The goal was to develop fully automated techniques to reduce the manual effort in such a modeling process. A fully automated segmentation technique based on Statical Parametric Mapping 8, including an improved tissue probability map and an automated correction routine for segmentation errors, was developed, along with an automated electrode placement tool for high-density arrays. The performance of these automated routines was evaluated against results from manual segmentation on four healthy subjects and seven stroke patients. The criteria include segmentation accuracy, the difference of current flow distributions in resulting HD-tDCS models and the optimized current flow intensities on cortical targets. The segmentation tool can segment out not just the brain but also provide accurate results for CSF, skull and other soft tissues with a field of view extending to the neck. Compared to manual results, automated segmentation deviates by only 7% and 18% for normal and stroke subjects, respectively. The predicted electric fields in the brain deviate by 12% and 29% respectively, which is well within the variability observed for various modeling choices. Finally, optimized current flow intensities on cortical targets do not differ significantly. Fully automated individualized modeling may now be feasible for large-sample EEG research studies and tDCS clinical trials.

Off- and Along-Axis Slow Spreading Ridge Segment Characters: Insights From 3d Thermal Modeling

NASA Astrophysics Data System (ADS)

Gac, S.; Tisseau, C.; Dyment, J.

2001-12-01

Many observations along the Mid-Atlantic Ridge segments suggest a correlation between surface characters (length, axial morphology) and the thermal state of the segment. Thibaud et al. (1998) classify segments according to their thermal state: "colder" segments shorter than 30 km show a weak magmatic activity, and "hotter" segments as long as 90 km show a robust magmatic activity. The existence of such a correlation suggests that the thermal structure of a slow spreading ridge segment explains most of the surface observations. Here we test the physical coherence of such an integrated thermal model and evaluate it quantitatively. The different kinds of segment would constitute different phases in a segment evolution, the segment evolving progressively from a "colder" to a "hotter" so to a "colder" state. Here we test the consistency of such an evolution scheme. To test these hypotheses we have developed a 3D numerical model for the thermal structure and evolution of a slow spreading ridge segment. The thermal structure is controlled by the geometry and the dimensions of a permanently hot zone, imposed beneath the segment center, where is simulated the adiabatic ascent of magmatic material. To compare the model with the observations several geophysic quantities which depend on the thermal state are simulated: crustal thickness variations along axis, gravity anomalies (reflecting density variations) and earthquake maximum depth (corresponding to the 750° C isotherm depth). The thermal structure of a particular segment is constrained by comparing the simulated quantities to the real ones. Considering realistic magnetization parameters, the magnetic anomalies generated from the same thermal structure and evolution reproduce the observed magnetic anomaly amplitude variations along the segment. The thermal structures accounting for observations are determined for each kind of segment (from "colder" to "hotter"). The evolution of the thermal structure from the "colder" to the "hotter" segments gives credence to a temporal relationship between the different kinds of segment. The resulting thermal evolution model of slow spreading ridge segments may explain the rhomboedric shapes observed off-axis.

CT-based manual segmentation and evaluation of paranasal sinuses.

PubMed

Pirner, S; Tingelhoff, K; Wagner, I; Westphal, R; Rilk, M; Wahl, F M; Bootz, F; Eichhorn, Klaus W G

2009-04-01

Manual segmentation of computed tomography (CT) datasets was performed for robot-assisted endoscope movement during functional endoscopic sinus surgery (FESS). Segmented 3D models are needed for the robots' workspace definition. A total of 50 preselected CT datasets were each segmented in 150-200 coronal slices with 24 landmarks being set. Three different colors for segmentation represent diverse risk areas. Extension and volumetric measurements were performed. Three-dimensional reconstruction was generated after segmentation. Manual segmentation took 8-10 h for each CT dataset. The mean volumes were: right maxillary sinus 17.4 cm(3), left side 17.9 cm(3), right frontal sinus 4.2 cm(3), left side 4.0 cm(3), total frontal sinuses 7.9 cm(3), sphenoid sinus right side 5.3 cm(3), left side 5.5 cm(3), total sphenoid sinus volume 11.2 cm(3). Our manually segmented 3D-models present the patient's individual anatomy with a special focus on structures in danger according to the diverse colored risk areas. For safe robot assistance, the high-accuracy models represent an average of the population for anatomical variations, extension and volumetric measurements. They can be used as a database for automatic model-based segmentation. None of the segmentation methods so far described provide risk segmentation. The robot's maximum distance to the segmented border can be adjusted according to the differently colored areas.

TARPARE: a method for selecting target audiences for public health interventions.

PubMed

Donovan, R J; Egger, G; Francas, M

1999-06-01

This paper presents a model to assist the health promotion practitioner systematically compare and select what might be appropriate target groups when there are a number of segments competing for attention and resources. TARPARE assesses previously identified segments on the following criteria: T: The Total number of persons in the segment; AR: The proportion of At Risk persons in the segment; P: The Persuability of the target audience; A: The Accessibility of the target audience; R: Resources required to meet the needs of the target audience; and E: Equity, social justice considerations. The assessment can be applied qualitatively or can be applied such that scores can be assigned to each segment. Two examples are presented. TARPARE is a useful and flexible model for understanding the various segments in a population of interest and for assessing the potential viability of interventions directed at each segment. The model is particularly useful when there is a need to prioritise segments in terms of available budgets. The model provides a disciplined approach to target selection and forces consideration of what weights should be applied to the different criteria, and how these might vary for different issues or for different objectives. TARPARE also assesses segments in terms of an overall likelihood of optimal impact for each segment. Targeting high scoring segments is likely to lead to greater program success than targeting low scoring segments.

Novel Therapy for Bone Regeneration in Large Segmental Defects

DTIC Science & Technology

2017-12-01

HC, Giannoudis PV. Fat embolism and IM nailing. Injury. 2006;37(Suppl 4):S1–2. 38. Wenda K, Ritter G, Degreif J, Rudigier J. Pathogenesis of pul...morphogenetic protein (BMP), thrombopoietin (TPO), therapy, fracture healing, bone regeneration, minipig, pig 16. SECURITY CLASSIFICATION OF: 17... fracture healing, bone regeneration, minipig, pig 3. OVERALL PROJECT SUMMARY: Project start date 30/09/2013 Project end date 29/09/2017 (with 1 year NCE

Novel Therapy for Bone Regeneration in Large Segmental Defects

DTIC Science & Technology

2017-12-01

healing. Clin Orthop Relat Res. 1998;355(Suppl):S230–8. 37. Pape HC, Giannoudis PV. Fat embolism and IM nailing. Injury. 2006;37(Suppl 4):S1–2. 38. Wenda...mechanisms to elicit bone healing. 15. SUBJECT TERMS Bone healing, bone morphogenetic protein (BMP), thrombopoietin (TPO), therapy, fracture healing...thrombopoietin (TPO), therapy, fracture healing, bone regeneration, minipig, pig 3. OVERALL PROJECT SUMMARY: Project start date 30/09/2013 Project end

Cri du Chat Syndrome and Primary Ciliary Dyskinesia: A Common Genetic Cause on Chromosome 5p

PubMed Central

Shapiro, Adam J.; Weck, Karen E.; Chao, Kay C.; Rosenfeld, Margaret; Nygren, Anders O. H.; Knowles, Michael R.; Leigh, Margaret W.; Zariwala, Maimoona A.

2014-01-01

Cri du chat syndrome (CdCS) and primary ciliary dyskinesia (PCD) are rare diseases that present with frequent respiratory symptoms. PCD can be caused by hemizygous DNAH5 mutation in combination with a 5p segmental deletion attributable to CdCS on the opposite chromosome. Chronic oto-sino-pulmonary symptoms or organ laterality defects in CdCS should prompt an evaluation for PCD. PMID:25066065

Optimizing Soft Tissue Management and Spacer Design in Segmental Bone Defects

DTIC Science & Technology

2014-10-01

the time of the “Pre-Procedure”. Autogenous Cancellous Bone Graft (ACBG harvested from the sternum at the time of the treatment surgery is used as...will receive more specialized training and orientation to microCT analysis, both on a theoretical and practical level. He will work with raw CT...adjacent to the PMMA) composed of mononuclear cells and exhibited extensive, diffuse fibrous connective tissue.  Performed histology on goat autogenous

Histologic Evaluation of Critical Size Defect Healing With Natural and Synthetic Bone Grafts in the Pigeon ( Columba livia ) Ulna.

PubMed

Tunio, Ahmed; Jalila, Abu; Goh, Yong Meng; Shameha-Intan; Shanthi, Ganabadi

2015-06-01

Fracture and bone segment loss are major clinical problems in birds. Achieving bone formation and clinical union in a fracture case is important for the survival of the bird. To evaluate the efficacy of bone grafts for defect healing in birds, 2 different bone grafts were investigated in the healing of a bone defect in 24 healthy pigeons ( Columba livia ). In each bird, a 1-cm critical size defect (CSD) was created in the left ulna, and the fracture was stabilized with external skeletal fixation (ESF). A graft of hydroxyapatite (HA) alone (n = 12 birds) or demineralized bone matrix (DBM) combined with HA (n = 12 birds) was implanted in the CSD. The CSD healing was evaluated at 3 endpoints: 3, 6, and 12 weeks after surgery. Four birds were euthanatized at each endpoint from each treatment group, and bone graft healing in the ulna CSD was evaluated by histologic examination. The CSD and graft implants were evaluated for quality of union, cortex development, and bone graft incorporation. Results showed no graft rejection in any bird, and all birds had connective tissue formation in the defect because of the bone graft application. These results suggest that bone defect healing can be achieved by a combination of osteoinductive and osteoconductive bone graft materials for clinical union and new bone regeneration in birds. The combination of DBM and HA resulted in a better quality bone graft (P < .05) than did HA alone, but there was no significant differences in cortex development or bone graft incorporation at 3, 6, or 12 weeks. From the results of this study, we conclude that HA bone grafts, alone or in combination with DBM, with external skeletal fixation is suitable and safe for bone defect and fracture treatment in pigeons.

The impact of RABL2B gene (rs144944885) on human male infertility in patients with oligoasthenoteratozoospermia and immotile short tail sperm defects.

PubMed

Hosseini, Seyedeh Hanieh; Sadighi Gilani, Mohammad Ali; Meybodi, Anahita Mohseni; Sabbaghian, Marjan

2017-04-01

Male infertility is a multifactorial disorder with impressively genetic basis; besides, sperm abnormalities are the cause of numerous cases of male infertility. In this study, we evaluated the genetic variants in exons 4 and 5 and their intron-exon boundaries in RABL2B gene in infertile men with oligoasthenoteratozoospermia (OAT) and immotile short tail sperm (ISTS) defects to define if there is any association between these variants and human male infertility. To this purpose, DNA was extracted from peripheral blood and after PCR reaction and sequencing, the results of sequenced segments were analyzed. In the present study, 30 infertile men with ISTS defect and 30 oligoasthenoteratozoospermic infertile men were recruited. All men were of Iranian origin and it took 3 years to collect patient's samples with ISTS defect. As a result, the 50776482 delC intronic variant (rs144944885) was identified in five patients with oligoasthenoteratozoospermia defect and one patient with ISTS defect in heterozygote form. This variant was not identified in controls. The allelic frequency of the 50776482 delC variant was significantly statistically higher in oligoasthenoteratozoospermic infertile men (p < 0.05). Bioinformatics studies suggested that the 50776482 delC allele would modify the splicing of RABL2B pre-mRNA. In addition, we identified a new genetic variant in RABL2B gene. According to the present study, 50776482 delC allele in the RABL2B gene could be a risk factor in Iranian infertile men with oligoasthenoteratozoospermia defect, but more genetic studies are required to understand the accurate role of this variant in pathogenesis of human male infertility.

Variations of pulmonary arteries and other associated defects in Tetralogy of Fallot.

PubMed

Sheikh, Abdul Malik; Kazmi, Uzma; Syed, Najam Hyder

2014-01-01

The objective of study was to determine pulmonary artery variations and other associated cardiac defects in patients with Tetralogy of Fallot. This cross-sectional, descriptive study was carried out at The Children's Hospital and the Institute of Child Health, Lahore, from January 2006 to December 2012. All patients with Tetralogy of Fallot, who underwent cardiac catheterization during this period, were included. Standard cine-angiograms were done to record the pulmonary artery sizes and associated cardiac defects. A total of 576 patients with Tetralogy of Fallot were catheterized. Pulmonary Artery abnormalities were present in 109 (18.92%) patients. The commonest abnormality was isolated Left Pulmonary Artery stenosis (n = 60, 10.4%) followed by supra-valvular stenosis (n = 9, 1.6%). Left Pulmonary Artery was absent in seven patients(1.2%), while 1 patient (0.2%) had both absent right and left Pulmonary Arteries with segmental branch pulmonary arteries originating directly from Main Pulmonary Artery. Associated cardiac lesions included right aortic arch in 72 (12.5%), additional muscular Ventricular Septal Defect in 31 (5.4%), Patent Ductus Arteriosus in 31 (5.4%), bilateral Superior Vena Cava 36(6.2%), Atrial Septal Defect 4(0.7%) and Major Aortopulmonary Collateral Arteries in 75(13%) patients. Significant coronary artery abnormalities were present in 28(4.9%) children. Pulmonary artery abnormalities were present in 18.92% of patients with Tetralogy of Fallot. Isolated Left Pulmonary Artery origin stenosis was the most common abnormality. Significant associated cardiac lesions including Patent Ductus Arteriosus , additional muscular Ventricular Septal Defect, coronary artery abnormalities, bilateral Superior Vena Cava, Atrial Septal Defect and Major Aortopulmonary Collateral Arteries were present in one-third of the patients.

Mechanisms of Barrett’s esophagus (clinical): LES dysfunction, hiatal hernia, peristaltic defects

PubMed Central

Roman, Sabine; Kahrilas, Peter J

2014-01-01

Summary Barrett’s esophagus, with the potential to develop into esophageal adenocarcinoma (EAC), is a major complication of gastroesophageal reflux disease (GERD). However, about 50% of patients developing EAC had no known GERD beforehand. Hence, while GERD symptoms, esophagitis, and Barrett’s have a number of common determinants (esophagogastric junction (EGJ) incompetence, impaired esophageal clearance mechanisms, hiatus hernia) they also have some independent determinants. Further, although excess esophageal acid exposure plays a major role in the genesis of long-segment Barrett’s esophagus there is minimal evidence supporting this for short-segment Barrett’s. Hence, these may have unique pathophysiological features as well. Long-segment Barrett’s seems to share most, if not all, of the risk factors for esophagitis, particularly high-grade esophagitis. However, it is uncertain if EGJ function and acid clearance are more severely impaired in patients with long-segment Barrett’s compared to patients with high-grade esophagitis. With respect to short-segment Barrett’s, the acid pocket may play an important pathogenic role. Conceptually, extension of the acid pocket into the distal esophagus, also known as intra-sphincteric reflux, provides a mechanism or acid exposure of the distal esophageal mucosa without the occurrence of discrete reflux events, which are more likely to prompt reflux symptoms and lead to the development of esophagitis. Hence, intra-sphincteric reflux related to extension of the acid/no acid interface at the proximal margin of the acid pocket may be key in the development of short segment Barrett’s. However, currently this is still somewhat speculative and further studies are required to confirm this. PMID:25743453

Discrete wavelet-aided delineation of PCG signal events via analysis of an area curve length-based decision statistic.

PubMed

Homaeinezhad, M R; Atyabi, S A; Daneshvar, E; Ghaffari, A; Tahmasebi, M

2010-12-01

The aim of this study is to describe a robust unified framework for segmentation of the phonocardiogram (PCG) signal sounds based on the false-alarm probability (FAP) bounded segmentation of a properly calculated detection measure. To this end, first the original PCG signal is appropriately pre-processed and then, a fixed sample size sliding window is moved on the pre-processed signal. In each slid, the area under the excerpted segment is multiplied by its curve-length to generate the Area Curve Length (ACL) metric to be used as the segmentation decision statistic (DS). Afterwards, histogram parameters of the nonlinearly enhanced DS metric are used for regulation of the α-level Neyman-Pearson classifier for FAP-bounded delineation of the PCG events. The proposed method was applied to all 85 records of Nursing Student Heart Sounds database (NSHSDB) including stenosis, insufficiency, regurgitation, gallop, septal defect, split sound, rumble, murmur, clicks, friction rub and snap disorders with different sampling frequencies. Also, the method was applied to the records obtained from an electronic stethoscope board designed for fulfillment of this study in the presence of high-level power-line noise and external disturbing sounds and as the results, no false positive (FP) or false negative (FN) errors were detected. High noise robustness, acceptable detection-segmentation accuracy of PCG events in various cardiac system conditions, and having no parameters dependency to the acquisition sampling frequency can be mentioned as the principal virtues and abilities of the proposed ACL-based PCG events detection-segmentation algorithm.

Mechanisms of Barrett's oesophagus (clinical): LOS dysfunction, hiatal hernia, peristaltic defects.

PubMed

Roman, Sabine; Kahrilas, Peter J

2015-02-01

Barrett's oesophagus, with the potential to develop into oesophageal adenocarcinoma (OAC), is a major complication of gastrooesophageal reflux disease (GORD). However, about 50% of patients developing OAC had no known GORD beforehand. Hence, while GORD symptoms, oesophagitis, and Barrett's have a number of common determinants (oesophagogastric junction (OGJ) incompetence, impaired oesophageal clearance mechanisms, hiatus hernia) they also have some independent determinants. Further, although excess oesophageal acid exposure plays a major role in the genesis of long-segment Barrett's oesophagus there is minimal evidence supporting this for short-segment Barrett's. Hence, these may have unique pathophysiological features as well. Long-segment Barrett's seems to share most, if not all, of the risk factors for oesophagitis, particularly high-grade oesophagitis. However, it is uncertain if OGJ function and acid clearance are more severely impaired in patients with long-segment Barrett's compared to patients with high-grade oesophagitis. With respect to short-segment Barrett's, the acid pocket may play an important pathogenic role. Conceptually, extension of the acid pocket into the distal oesophagus, also known as intra-sphincteric reflux, provides a mechanism or acid exposure of the distal osophageal mucosa without the occurrence of discrete reflux events, which are more likely to prompt reflux symptoms and lead to the development of oesophagitis. Hence, intra-sphincteric reflux related to extension of the acid/no acid interface at the proximal margin of the acid pocket may be key in the development of short segment Barrett's. However, currently this is still somewhat speculative and further studies are required to confirm this. Copyright © 2014 Elsevier Ltd. All rights reserved.

Stress distribution pattern of screw-retained restorations with segmented vs. non-segmented abutments: A finite element analysis

PubMed Central

Aalaei, Shima; Rajabi Naraki, Zahra; Nematollahi, Fatemeh; Beyabanaki, Elaheh; Shahrokhi Rad, Afsaneh

2017-01-01

Background. Screw-retained restorations are favored in some clinical situations such as limited inter-occlusal spaces. This study was designed to compare stresses developed in the peri-implant bone in two different types of screw-retained restorations (segmented vs. non-segmented abutment) using a finite element model. Methods. An implant, 4.1 mm in diameter and 10 mm in length, was placed in the first molar site of a mandibular model with 1 mm of cortical bone on the buccal and lingual sides. Segmented and non-segmented screw abutments with their crowns were placed on the simulated implant in each model. After loading (100 N, axial and 45° non-axial), von Mises stress was recorded using ANSYS software, version 12.0.1. Results. The maximum stresses in the non-segmented abutment screw were less than those of segmented abutment (87 vs. 100, and 375 vs. 430 MPa under axial and non-axial loading, respectively). The maximum stresses in the peri-implant bone for the model with segmented abutment were less than those of non-segmented ones (21 vs. 24 MPa, and 31 vs. 126 MPa under vertical and angular loading, respectively). In addition, the micro-strain of peri-implant bone for the segmented abutment restoration was less than that of non-segmented abutment. Conclusion. Under axial and non-axial loadings, non-segmented abutment showed less stress concentration in the screw, while there was less stress and strain in the peri-implant bone in the segmented abutment. PMID:29184629

Deformable M-Reps for 3D Medical Image Segmentation.

PubMed

Pizer, Stephen M; Fletcher, P Thomas; Joshi, Sarang; Thall, Andrew; Chen, James Z; Fridman, Yonatan; Fritsch, Daniel S; Gash, Graham; Glotzer, John M; Jiroutek, Michael R; Lu, Conglin; Muller, Keith E; Tracton, Gregg; Yushkevich, Paul; Chaney, Edward L

2003-11-01

M-reps (formerly called DSLs) are a multiscale medial means for modeling and rendering 3D solid geometry. They are particularly well suited to model anatomic objects and in particular to capture prior geometric information effectively in deformable models segmentation approaches. The representation is based on figural models , which define objects at coarse scale by a hierarchy of figures - each figure generally a slab representing a solid region and its boundary simultaneously. This paper focuses on the use of single figure models to segment objects of relatively simple structure. A single figure is a sheet of medial atoms, which is interpolated from the model formed by a net, i.e., a mesh or chain, of medial atoms (hence the name m-reps ), each atom modeling a solid region via not only a position and a width but also a local figural frame giving figural directions and an object angle between opposing, corresponding positions on the boundary implied by the m-rep. The special capability of an m-rep is to provide spatial and orientational correspondence between an object in two different states of deformation. This ability is central to effective measurement of both geometric typicality and geometry to image match, the two terms of the objective function optimized in segmentation by deformable models. The other ability of m-reps central to effective segmentation is their ability to support segmentation at multiple levels of scale, with successively finer precision. Objects modeled by single figures are segmented first by a similarity transform augmented by object elongation, then by adjustment of each medial atom, and finally by displacing a dense sampling of the m-rep implied boundary. While these models and approaches also exist in 2D, we focus on 3D objects. The segmentation of the kidney from CT and the hippocampus from MRI serve as the major examples in this paper. The accuracy of segmentation as compared to manual, slice-by-slice segmentation is reported.

Deformable M-Reps for 3D Medical Image Segmentation

PubMed Central

Pizer, Stephen M.; Fletcher, P. Thomas; Joshi, Sarang; Thall, Andrew; Chen, James Z.; Fridman, Yonatan; Fritsch, Daniel S.; Gash, Graham; Glotzer, John M.; Jiroutek, Michael R.; Lu, Conglin; Muller, Keith E.; Tracton, Gregg; Yushkevich, Paul; Chaney, Edward L.

2013-01-01

M-reps (formerly called DSLs) are a multiscale medial means for modeling and rendering 3D solid geometry. They are particularly well suited to model anatomic objects and in particular to capture prior geometric information effectively in deformable models segmentation approaches. The representation is based on figural models, which define objects at coarse scale by a hierarchy of figures – each figure generally a slab representing a solid region and its boundary simultaneously. This paper focuses on the use of single figure models to segment objects of relatively simple structure. A single figure is a sheet of medial atoms, which is interpolated from the model formed by a net, i.e., a mesh or chain, of medial atoms (hence the name m-reps), each atom modeling a solid region via not only a position and a width but also a local figural frame giving figural directions and an object angle between opposing, corresponding positions on the boundary implied by the m-rep. The special capability of an m-rep is to provide spatial and orientational correspondence between an object in two different states of deformation. This ability is central to effective measurement of both geometric typicality and geometry to image match, the two terms of the objective function optimized in segmentation by deformable models. The other ability of m-reps central to effective segmentation is their ability to support segmentation at multiple levels of scale, with successively finer precision. Objects modeled by single figures are segmented first by a similarity transform augmented by object elongation, then by adjustment of each medial atom, and finally by displacing a dense sampling of the m-rep implied boundary. While these models and approaches also exist in 2D, we focus on 3D objects. The segmentation of the kidney from CT and the hippocampus from MRI serve as the major examples in this paper. The accuracy of segmentation as compared to manual, slice-by-slice segmentation is reported. PMID:23825898

Utilizing optical coherence tomography for CAD/CAM of indirect dental restorations

NASA Astrophysics Data System (ADS)

Chityala, Ravishankar; Vidal, Carola; Jones, Robert

Optical Coherence Tomography (OCT) has seen broad application in dentistry including early carious lesion detection and imaging defects in resin composite restorations. This study investigates expanding the clinical usefulness by investigating methods to use OCT for obtaining three-dimensional (3D) digital impressions, which can be integrated to CAD/CAM manufacturing of indirect restorations. 3D surface topography `before' and `after' a cavity preparation was acquired by an intraoral cross polarization swept source OCT (CP-OCT) system with a Micro-Electro-Mechanical System (MEMS) scanning mirror. Image registration and segmentation methods were used to digitally construct a replacement restoration that modeled the original surface morphology of a hydroxyapatite sample. After high resolution additive manufacturing (e.g. polymer 3D printing) of the replacement restoration, micro-CT imaging was performed to examine the marginal adaptation. This study establishes the protocol for further investigation of integrating OCT with CAD/CAM of indirect dental restorations.

Heuristic Bayesian segmentation for discovery of coexpressed genes within genomic regions.

PubMed

Pehkonen, Petri; Wong, Garry; Törönen, Petri

2010-01-01

Segmentation aims to separate homogeneous areas from the sequential data, and plays a central role in data mining. It has applications ranging from finance to molecular biology, where bioinformatics tasks such as genome data analysis are active application fields. In this paper, we present a novel application of segmentation in locating genomic regions with coexpressed genes. We aim at automated discovery of such regions without requirement for user-given parameters. In order to perform the segmentation within a reasonable time, we use heuristics. Most of the heuristic segmentation algorithms require some decision on the number of segments. This is usually accomplished by using asymptotic model selection methods like the Bayesian information criterion. Such methods are based on some simplification, which can limit their usage. In this paper, we propose a Bayesian model selection to choose the most proper result from heuristic segmentation. Our Bayesian model presents a simple prior for the segmentation solutions with various segment numbers and a modified Dirichlet prior for modeling multinomial data. We show with various artificial data sets in our benchmark system that our model selection criterion has the best overall performance. The application of our method in yeast cell-cycle gene expression data reveals potential active and passive regions of the genome.

Segmenting the thoracic, abdominal and pelvic musculature on CT scans combining atlas-based model and active contour model

NASA Astrophysics Data System (ADS)

Zhang, Weidong; Liu, Jiamin; Yao, Jianhua; Summers, Ronald M.

2013-03-01

Segmentation of the musculature is very important for accurate organ segmentation, analysis of body composition, and localization of tumors in the muscle. In research fields of computer assisted surgery and computer-aided diagnosis (CAD), muscle segmentation in CT images is a necessary pre-processing step. This task is particularly challenging due to the large variability in muscle structure and the overlap in intensity between muscle and internal organs. This problem has not been solved completely, especially for all of thoracic, abdominal and pelvic regions. We propose an automated system to segment the musculature on CT scans. The method combines an atlas-based model, an active contour model and prior segmentation of fat and bones. First, body contour, fat and bones are segmented using existing methods. Second, atlas-based models are pre-defined using anatomic knowledge at multiple key positions in the body to handle the large variability in muscle shape. Third, the atlas model is refined using active contour models (ACM) that are constrained using the pre-segmented bone and fat. Before refining using ACM, the initialized atlas model of next slice is updated using previous atlas. The muscle is segmented using threshold and smoothed in 3D volume space. Thoracic, abdominal and pelvic CT scans were used to evaluate our method, and five key position slices for each case were selected and manually labeled as the reference. Compared with the reference ground truth, the overlap ratio of true positives is 91.1%+/-3.5%, and that of false positives is 5.5%+/-4.2%.

PSNet: prostate segmentation on MRI based on a convolutional neural network.

PubMed

Tian, Zhiqiang; Liu, Lizhi; Zhang, Zhenfeng; Fei, Baowei

2018-04-01

Automatic segmentation of the prostate on magnetic resonance images (MRI) has many applications in prostate cancer diagnosis and therapy. We proposed a deep fully convolutional neural network (CNN) to segment the prostate automatically. Our deep CNN model is trained end-to-end in a single learning stage, which uses prostate MRI and the corresponding ground truths as inputs. The learned CNN model can be used to make an inference for pixel-wise segmentation. Experiments were performed on three data sets, which contain prostate MRI of 140 patients. The proposed CNN model of prostate segmentation (PSNet) obtained a mean Dice similarity coefficient of [Formula: see text] as compared to the manually labeled ground truth. Experimental results show that the proposed model could yield satisfactory segmentation of the prostate on MRI.

Monti's procedure as an alternative technique in complex urethral distraction defect.

PubMed

Hosseini, Jalil; Kaviani, Ali; Mazloomfard, Mohammad M; Golshan, Ali R

2010-01-01

Pelvic fracture urethral distraction defect is usually managed by the end to end anastomotic urethroplasty. Surgical repair of those patients with post-traumatic complex posterior urethral defects, who have undergone failed previous surgical treatments, remains one of the most challenging problems in urology. Appendix urinary diversion could be used in such cases. However, the appendix tissue is not always usable. We report our experience on management of patients with long urethral defect with history of one or more failed urethroplasties by Monti channel urinary diversion. From 2001 to 2007, we evaluated data from 8 male patients aged 28 to 76 years (mean age 42.5) in whom the Monti technique was performed. All cases had history of posterior urethral defect with one or more failed procedures for urethral reconstruction including urethroplasty. A 2 to 2.5 cm segment of ileum, which had a suitable blood supply, was cut. After the re-anastomosis of the ileum, we closed the opened ileum transversely surrounding a 14-16 Fr urethral catheter using running Vicryl sutures. The newly built tube was used as an appendix during diversion. All patients performed catheterization through the conduit without difficulty and stomal stenosis. Mild stomal incontinence occurred in one patient in the supine position who became continent after adjustment of the catheterization intervals. There was no dehiscence, necrosis or perforation of the tube. Based on our data, Monti's procedure seems to be a valuable technique in patients with very long complicated urethral defect who cannot be managed with routine urethroplastic techniques.

Active appearance model and deep learning for more accurate prostate segmentation on MRI

NASA Astrophysics Data System (ADS)

Cheng, Ruida; Roth, Holger R.; Lu, Le; Wang, Shijun; Turkbey, Baris; Gandler, William; McCreedy, Evan S.; Agarwal, Harsh K.; Choyke, Peter; Summers, Ronald M.; McAuliffe, Matthew J.

2016-03-01

Prostate segmentation on 3D MR images is a challenging task due to image artifacts, large inter-patient prostate shape and texture variability, and lack of a clear prostate boundary specifically at apex and base levels. We propose a supervised machine learning model that combines atlas based Active Appearance Model (AAM) with a Deep Learning model to segment the prostate on MR images. The performance of the segmentation method is evaluated on 20 unseen MR image datasets. The proposed method combining AAM and Deep Learning achieves a mean Dice Similarity Coefficient (DSC) of 0.925 for whole 3D MR images of the prostate using axial cross-sections. The proposed model utilizes the adaptive atlas-based AAM model and Deep Learning to achieve significant segmentation accuracy.

A mathematical model for Vertical Attitude Takeoff and Landing (VATOL) aircraft simulation. Volume 2: Model equations and base aircraft data

NASA Technical Reports Server (NTRS)

Fortenbaugh, R. L.

1980-01-01

Equations incorporated in a VATOL six degree of freedom off-line digital simulation program and data for the Vought SF-121 VATOL aircraft concept which served as the baseline for the development of this program are presented. The equations and data are intended to facilitate the development of a piloted VATOL simulation. The equation presentation format is to state the equations which define a particular model segment. Listings of constants required to quantify the model segment, input variables required to exercise the model segment, and output variables required by other model segments are included. In several instances a series of input or output variables are followed by a section number in parentheses which identifies the model segment of origination or termination of those variables.

A Stochastic-Variational Model for Soft Mumford-Shah Segmentation

PubMed Central

2006-01-01

In contemporary image and vision analysis, stochastic approaches demonstrate great flexibility in representing and modeling complex phenomena, while variational-PDE methods gain enormous computational advantages over Monte Carlo or other stochastic algorithms. In combination, the two can lead to much more powerful novel models and efficient algorithms. In the current work, we propose a stochastic-variational model for soft (or fuzzy) Mumford-Shah segmentation of mixture image patterns. Unlike the classical hard Mumford-Shah segmentation, the new model allows each pixel to belong to each image pattern with some probability. Soft segmentation could lead to hard segmentation, and hence is more general. The modeling procedure, mathematical analysis on the existence of optimal solutions, and computational implementation of the new model are explored in detail, and numerical examples of both synthetic and natural images are presented. PMID:23165059

On Inertial Body Tracking in the Presence of Model Calibration Errors

PubMed Central

Miezal, Markus; Taetz, Bertram; Bleser, Gabriele

2016-01-01

In inertial body tracking, the human body is commonly represented as a biomechanical model consisting of rigid segments with known lengths and connecting joints. The model state is then estimated via sensor fusion methods based on data from attached inertial measurement units (IMUs). This requires the relative poses of the IMUs w.r.t. the segments—the IMU-to-segment calibrations, subsequently called I2S calibrations—to be known. Since calibration methods based on static poses, movements and manual measurements are still the most widely used, potentially large human-induced calibration errors have to be expected. This work compares three newly developed/adapted extended Kalman filter (EKF) and optimization-based sensor fusion methods with an existing EKF-based method w.r.t. their segment orientation estimation accuracy in the presence of model calibration errors with and without using magnetometer information. While the existing EKF-based method uses a segment-centered kinematic chain biomechanical model and a constant angular acceleration motion model, the newly developed/adapted methods are all based on a free segments model, where each segment is represented with six degrees of freedom in the global frame. Moreover, these methods differ in the assumed motion model (constant angular acceleration, constant angular velocity, inertial data as control input), the state representation (segment-centered, IMU-centered) and the estimation method (EKF, sliding window optimization). In addition to the free segments representation, the optimization-based method also represents each IMU with six degrees of freedom in the global frame. In the evaluation on simulated and real data from a three segment model (an arm), the optimization-based method showed the smallest mean errors, standard deviations and maximum errors throughout all tests. It also showed the lowest dependency on magnetometer information and motion agility. Moreover, it was insensitive w.r.t. I2S position and segment length errors in the tested ranges. Errors in the I2S orientations were, however, linearly propagated into the estimated segment orientations. In the absence of magnetic disturbances, severe model calibration errors and fast motion changes, the newly developed IMU centered EKF-based method yielded comparable results with lower computational complexity. PMID:27455266

Design and analysis of forward and reverse models for predicting defect accumulation, defect energetics, and irradiation conditions

DOE PAGES

Stewart, James A.; Kohnert, Aaron A.; Capolungo, Laurent; ...

2018-03-06

The complexity of radiation effects in a material’s microstructure makes developing predictive models a difficult task. In principle, a complete list of all possible reactions between defect species being considered can be used to elucidate damage evolution mechanisms and its associated impact on microstructure evolution. However, a central limitation is that many models use a limited and incomplete catalog of defect energetics and associated reactions. Even for a given model, estimating its input parameters remains a challenge, especially for complex material systems. Here, we present a computational analysis to identify the extent to which defect accumulation, energetics, and irradiation conditionsmore » can be determined via forward and reverse regression models constructed and trained from large data sets produced by cluster dynamics simulations. A global sensitivity analysis, via Sobol’ indices, concisely characterizes parameter sensitivity and demonstrates how this can be connected to variability in defect evolution. Based on this analysis and depending on the definition of what constitutes the input and output spaces, forward and reverse regression models are constructed and allow for the direct calculation of defect accumulation, defect energetics, and irradiation conditions. Here, this computational analysis, exercised on a simplified cluster dynamics model, demonstrates the ability to design predictive surrogate and reduced-order models, and provides guidelines for improving model predictions within the context of forward and reverse engineering of mathematical models for radiation effects in a materials’ microstructure.« less

Design and analysis of forward and reverse models for predicting defect accumulation, defect energetics, and irradiation conditions

DOE Office of Scientific and Technical Information (OSTI.GOV)

Stewart, James A.; Kohnert, Aaron A.; Capolungo, Laurent

The complexity of radiation effects in a material’s microstructure makes developing predictive models a difficult task. In principle, a complete list of all possible reactions between defect species being considered can be used to elucidate damage evolution mechanisms and its associated impact on microstructure evolution. However, a central limitation is that many models use a limited and incomplete catalog of defect energetics and associated reactions. Even for a given model, estimating its input parameters remains a challenge, especially for complex material systems. Here, we present a computational analysis to identify the extent to which defect accumulation, energetics, and irradiation conditionsmore » can be determined via forward and reverse regression models constructed and trained from large data sets produced by cluster dynamics simulations. A global sensitivity analysis, via Sobol’ indices, concisely characterizes parameter sensitivity and demonstrates how this can be connected to variability in defect evolution. Based on this analysis and depending on the definition of what constitutes the input and output spaces, forward and reverse regression models are constructed and allow for the direct calculation of defect accumulation, defect energetics, and irradiation conditions. Here, this computational analysis, exercised on a simplified cluster dynamics model, demonstrates the ability to design predictive surrogate and reduced-order models, and provides guidelines for improving model predictions within the context of forward and reverse engineering of mathematical models for radiation effects in a materials’ microstructure.« less

Colour image segmentation using unsupervised clustering technique for acute leukemia images

NASA Astrophysics Data System (ADS)

Halim, N. H. Abd; Mashor, M. Y.; Nasir, A. S. Abdul; Mustafa, N.; Hassan, R.

2015-05-01

Colour image segmentation has becoming more popular for computer vision due to its important process in most medical analysis tasks. This paper proposes comparison between different colour components of RGB(red, green, blue) and HSI (hue, saturation, intensity) colour models that will be used in order to segment the acute leukemia images. First, partial contrast stretching is applied on leukemia images to increase the visual aspect of the blast cells. Then, an unsupervised moving k-means clustering algorithm is applied on the various colour components of RGB and HSI colour models for the purpose of segmentation of blast cells from the red blood cells and background regions in leukemia image. Different colour components of RGB and HSI colour models have been analyzed in order to identify the colour component that can give the good segmentation performance. The segmented images are then processed using median filter and region growing technique to reduce noise and smooth the images. The results show that segmentation using saturation component of HSI colour model has proven to be the best in segmenting nucleus of the blast cells in acute leukemia image as compared to the other colour components of RGB and HSI colour models.

Transport of triplet excitons along continuous 100 nm polyfluorene chains

DOE PAGES

Xi, Liang; Bird, Matthew; Mauro, Gina; ...

2014-12-03

Triplet excitons created in poly-2,7-(9,9-dihexyl)fluorene (pF) chains with end trap groups in solution are efficiently transported to and captured by the end groups. The triplets explore the entire lengths of the chains, even for ~100 nm long chains enabling determination of the completeness of end capping. The results show that the chains continuous: they may contain transient barriers or traps, such as those from fluctuations of dihedral angles, but are free of major defects that stop motion of the triplets. Quantitative determinations are aided by the addition of a strong electron donor, TMPD, which removes absorption bands of the end-trappedmore » triplets. For chains having at least one end trap, triplet capture is quantitative on the 1 µs timescale imposed by the use of the donor. Fractions of chains having no end traps were 0.15 for pF samples with anthraquinone (AQ) end traps and 0.063 with naphthylimide (NI) end traps. These determinations agreed with measurements by NMR for short (<40 polymer repeat units (PRU)) chains, where NMR determinations are accurate. The results find no evidence for traps or barriers to transport of triplets, and places limits on the possible presence of defects as impenetrable barriers to less than one per 300 PRU. The present results present a paradigm different from the current consensus, derived from observations of singlet excitons, that conjugated chains are divided into “segments,” perhaps by some kind of defects. For the present pF chains, the segmentation either does not apply to triplet excitons or is transient so that the defects are healed or surmounted in times much shorter than 1 µs. Triplets on chains without end trap groups transfer to chains with end traps on a slower time scale. Rate constants for these bimolecular triplet transfer reactions were found to increase with the length of the accepting chain, as did rate constants for triplet transfer to the chains from small molecules like biphenyl. As a result, a second set of polyfluorenes with 2-butyloctyl side chains was found to have a much lower completeness of end capping.« less

Evaluation of bone repair in the femur of rats submitted to laser therapy in different wavelengths: An image segmentation method of analysis

NASA Astrophysics Data System (ADS)

Queiroga, A. S.; Sousa, F. B.; Araújo, J. M. S.; Santos, S. D.; Sousa, C. D'f. S.; Quintans, T. C.; Almeida, T. P.; Nonaka, C. F. W.; Batista, L. V.; Limeira Junior, F. A.

2008-09-01

The aim of this study was to histologically assess the effect of laser therapy (LILT, 660 and 780 nm) on the repair of standardized bone defects on the femur of Wistar albinus rats. The sample was composed of 12 Wistar albinus young adult rats of both genders. Three randomized groups were studied: group I (control, n = 4), group II (LILT, 660 nm, n = 4), and group III (LILT, 780 nm, n = 4). Samples were prepared using a bone defect on the left-side femur surface of the animals, with a total dimension of approximately 3 mm3. Groups II and III were irradiated every 48 h from the second application, where the first dose was given immediately after surgery and the second application came 24 h after surgery. The irradiations were applied transcutaneously at four points around the wound for 14 days. At each point, a dose of 50 J/cm2 (2 J) was given ( s ˜ 0.04 cm2, 40 mW) and the total dose per session was 200 J/cm2 (8 J). The sacrifices were made 15 days after surgery and the specimens were routinely processed to wax, serially cut, stained with an H&E stain, and analyzed under light microscopy. The images were submitted to morphometric analysis using the image segmentation method using the K-means algorithm. The data obtained through the morphometric analysis were submitted to statistical analysis using the Tukey test. The results showed that the group treated with laser therapy in the infrared spectrum resulted in an increase in the repair of bone defects when compared with the group treated with the laser in the red spectrum and control group, which, in turn, had a very similar pattern of repair. A statistical significance ( p < 0.01) was observed when comparing the results of group III and the results of Groups I and II. We concluded that the LILT in the infrared spectrum produced a positive biomodulation effect on the repair of bone defects in the femur of rats.

DOE Office of Scientific and Technical Information (OSTI.GOV)

Xi, Liang; Bird, Matthew; Mauro, Gina

Triplet excitons created in poly-2,7-(9,9-dihexyl)fluorene (pF) chains with end trap groups in solution are efficiently transported to and captured by the end groups. The triplets explore the entire lengths of the chains, even for ~100 nm long chains enabling determination of the completeness of end capping. The results show that the chains continuous: they may contain transient barriers or traps, such as those from fluctuations of dihedral angles, but are free of major defects that stop motion of the triplets. Quantitative determinations are aided by the addition of a strong electron donor, TMPD, which removes absorption bands of the end-trappedmore » triplets. For chains having at least one end trap, triplet capture is quantitative on the 1 µs timescale imposed by the use of the donor. Fractions of chains having no end traps were 0.15 for pF samples with anthraquinone (AQ) end traps and 0.063 with naphthylimide (NI) end traps. These determinations agreed with measurements by NMR for short (<40 polymer repeat units (PRU)) chains, where NMR determinations are accurate. The results find no evidence for traps or barriers to transport of triplets, and places limits on the possible presence of defects as impenetrable barriers to less than one per 300 PRU. The present results present a paradigm different from the current consensus, derived from observations of singlet excitons, that conjugated chains are divided into “segments,” perhaps by some kind of defects. For the present pF chains, the segmentation either does not apply to triplet excitons or is transient so that the defects are healed or surmounted in times much shorter than 1 µs. Triplets on chains without end trap groups transfer to chains with end traps on a slower time scale. Rate constants for these bimolecular triplet transfer reactions were found to increase with the length of the accepting chain, as did rate constants for triplet transfer to the chains from small molecules like biphenyl. As a result, a second set of polyfluorenes with 2-butyloctyl side chains was found to have a much lower completeness of end capping.« less

MRI and Additive Manufacturing of Nasal Alar Constructs for Patient-specific Reconstruction.

PubMed

Visscher, Dafydd O; van Eijnatten, Maureen; Liberton, Niels P T J; Wolff, Jan; Hofman, Mark B M; Helder, Marco N; Don Griot, J Peter W; Zuijlen, Paul P M van

2017-08-30

Surgical reconstruction of cartilaginous defects remains a major challenge. In the current study, we aimed to identify an imaging strategy for the development of patient-specific constructs that aid in the reconstruction of nasal deformities. Magnetic Resonance Imaging (MRI) was performed on a human cadaver head to find the optimal MRI sequence for nasal cartilage. This sequence was subsequently used on a volunteer. Images of both were assessed by three independent researchers to determine measurement error and total segmentation time. Three dimensionally (3D) reconstructed alar cartilage was then additively manufactured. Validity was assessed by comparing manually segmented MR images to the gold standard (micro-CT). Manual segmentation allowed delineation of the nasal cartilages. Inter- and intra-observer agreement was acceptable in the cadaver (coefficient of variation 4.6-12.5%), but less in the volunteer (coefficient of variation 0.6-21.9%). Segmentation times did not differ between observers (cadaver P = 0.36; volunteer P = 0.6). The lateral crus of the alar cartilage was consistently identified by all observers, whereas part of the medial crus was consistently missed. This study suggests that MRI is a feasible imaging modality for the development of 3D alar constructs for patient-specific reconstruction.

Multi-object model-based multi-atlas segmentation for rodent brains using dense discrete correspondences

NASA Astrophysics Data System (ADS)

Lee, Joohwi; Kim, Sun Hyung; Styner, Martin

2016-03-01

The delineation of rodent brain structures is challenging due to low-contrast multiple cortical and subcortical organs that are closely interfacing to each other. Atlas-based segmentation has been widely employed due to its ability to delineate multiple organs at the same time via image registration. The use of multiple atlases and subsequent label fusion techniques has further improved the robustness and accuracy of atlas-based segmentation. However, the accuracy of atlas-based segmentation is still prone to registration errors; for example, the segmentation of in vivo MR images can be less accurate and robust against image artifacts than the segmentation of post mortem images. In order to improve the accuracy and robustness of atlas-based segmentation, we propose a multi-object, model-based, multi-atlas segmentation method. We first establish spatial correspondences across atlases using a set of dense pseudo-landmark particles. We build a multi-object point distribution model using those particles in order to capture inter- and intra- subject variation among brain structures. The segmentation is obtained by fitting the model into a subject image, followed by label fusion process. Our result shows that the proposed method resulted in greater accuracy than comparable segmentation methods, including a widely used ANTs registration tool.

Analysis of a kinetic multi-segment foot model. Part I: Model repeatability and kinematic validity.

PubMed

Bruening, Dustin A; Cooney, Kevin M; Buczek, Frank L

2012-04-01

Kinematic multi-segment foot models are still evolving, but have seen increased use in clinical and research settings. The addition of kinetics may increase knowledge of foot and ankle function as well as influence multi-segment foot model evolution; however, previous kinetic models are too complex for clinical use. In this study we present a three-segment kinetic foot model and thorough evaluation of model performance during normal gait. In this first of two companion papers, model reference frames and joint centers are analyzed for repeatability, joint translations are measured, segment rigidity characterized, and sample joint angles presented. Within-tester and between-tester repeatability were first assessed using 10 healthy pediatric participants, while kinematic parameters were subsequently measured on 17 additional healthy pediatric participants. Repeatability errors were generally low for all sagittal plane measures as well as transverse plane Hindfoot and Forefoot segments (median<3°), while the least repeatable orientations were the Hindfoot coronal plane and Hallux transverse plane. Joint translations were generally less than 2mm in any one direction, while segment rigidity analysis suggested rigid body behavior for the Shank and Hindfoot, with the Forefoot violating the rigid body assumptions in terminal stance/pre-swing. Joint excursions were consistent with previously published studies. Copyright © 2012 Elsevier B.V. All rights reserved.

Segmenting words from natural speech: subsegmental variation in segmental cues.

PubMed

Rytting, C Anton; Brew, Chris; Fosler-Lussier, Eric

2010-06-01

Most computational models of word segmentation are trained and tested on transcripts of speech, rather than the speech itself, and assume that speech is converted into a sequence of symbols prior to word segmentation. We present a way of representing speech corpora that avoids this assumption, and preserves acoustic variation present in speech. We use this new representation to re-evaluate a key computational model of word segmentation. One finding is that high levels of phonetic variability degrade the model's performance. While robustness to phonetic variability may be intrinsically valuable, this finding needs to be complemented by parallel studies of the actual abilities of children to segment phonetically variable speech.

Deep convolutional neural network for prostate MR segmentation

NASA Astrophysics Data System (ADS)

Tian, Zhiqiang; Liu, Lizhi; Fei, Baowei

2017-03-01

Automatic segmentation of the prostate in magnetic resonance imaging (MRI) has many applications in prostate cancer diagnosis and therapy. We propose a deep fully convolutional neural network (CNN) to segment the prostate automatically. Our deep CNN model is trained end-to-end in a single learning stage based on prostate MR images and the corresponding ground truths, and learns to make inference for pixel-wise segmentation. Experiments were performed on our in-house data set, which contains prostate MR images of 20 patients. The proposed CNN model obtained a mean Dice similarity coefficient of 85.3%+/-3.2% as compared to the manual segmentation. Experimental results show that our deep CNN model could yield satisfactory segmentation of the prostate.

Adaptive segmentation of cerebrovascular tree in time-of-flight magnetic resonance angiography.

PubMed

Hao, J T; Li, M L; Tang, F L

2008-01-01

Accurate segmentation of the human vasculature is an important prerequisite for a number of clinical procedures, such as diagnosis, image-guided neurosurgery and pre-surgical planning. In this paper, an improved statistical approach to extracting whole cerebrovascular tree in time-of-flight magnetic resonance angiography is proposed. Firstly, in order to get a more accurate segmentation result, a localized observation model is proposed instead of defining the observation model over the entire dataset. Secondly, for the binary segmentation, an improved Iterative Conditional Model (ICM) algorithm is presented to accelerate the segmentation process. The experimental results showed that the proposed algorithm can obtain more satisfactory segmentation results and save more processing time than conventional approaches, simultaneously.

Fast Appearance Modeling for Automatic Primary Video Object Segmentation.

PubMed

Yang, Jiong; Price, Brian; Shen, Xiaohui; Lin, Zhe; Yuan, Junsong

2016-02-01

Automatic segmentation of the primary object in a video clip is a challenging problem as there is no prior knowledge of the primary object. Most existing techniques thus adapt an iterative approach for foreground and background appearance modeling, i.e., fix the appearance model while optimizing the segmentation and fix the segmentation while optimizing the appearance model. However, these approaches may rely on good initialization and can be easily trapped in local optimal. In addition, they are usually time consuming for analyzing videos. To address these limitations, we propose a novel and efficient appearance modeling technique for automatic primary video object segmentation in the Markov random field (MRF) framework. It embeds the appearance constraint as auxiliary nodes and edges in the MRF structure, and can optimize both the segmentation and appearance model parameters simultaneously in one graph cut. The extensive experimental evaluations validate the superiority of the proposed approach over the state-of-the-art methods, in both efficiency and effectiveness.

Segmentation of deformable organs from medical images using particle swarm optimization and nonlinear shape priors

NASA Astrophysics Data System (ADS)

Afifi, Ahmed; Nakaguchi, Toshiya; Tsumura, Norimichi

2010-03-01

In many medical applications, the automatic segmentation of deformable organs from medical images is indispensable and its accuracy is of a special interest. However, the automatic segmentation of these organs is a challenging task according to its complex shape. Moreover, the medical images usually have noise, clutter, or occlusion and considering the image information only often leads to meager image segmentation. In this paper, we propose a fully automated technique for the segmentation of deformable organs from medical images. In this technique, the segmentation is performed by fitting a nonlinear shape model with pre-segmented images. The kernel principle component analysis (KPCA) is utilized to capture the complex organs deformation and to construct the nonlinear shape model. The presegmentation is carried out by labeling each pixel according to its high level texture features extracted using the overcomplete wavelet packet decomposition. Furthermore, to guarantee an accurate fitting between the nonlinear model and the pre-segmented images, the particle swarm optimization (PSO) algorithm is employed to adapt the model parameters for the novel images. In this paper, we demonstrate the competence of proposed technique by implementing it to the liver segmentation from computed tomography (CT) scans of different patients.

Transport-reaction model for defect and carrier behavior within displacement cascades in gallium arsenide

DOE Office of Scientific and Technical Information (OSTI.GOV)

Wampler, William R.; Myers, Samuel M.

2014-02-01

A model is presented for recombination of charge carriers at displacement damage in gallium arsenide, which includes clustering of the defects in atomic displacement cascades produced by neutron or ion irradiation. The carrier recombination model is based on an atomistic description of capture and emission of carriers by the defects with time evolution resulting from the migration and reaction of the defects. The physics and equations on which the model is based are presented, along with details of the numerical methods used for their solution. The model uses a continuum description of diffusion, field-drift and reaction of carriers and defectsmore » within a representative spherically symmetric cluster. The initial radial defect profiles within the cluster were chosen through pair-correlation-function analysis of the spatial distribution of defects obtained from the binary-collision code MARLOWE, using recoil energies for fission neutrons. Charging of the defects can produce high electric fields within the cluster which may influence transport and reaction of carriers and defects, and which may enhance carrier recombination through band-to-trap tunneling. Properties of the defects are discussed and values for their parameters are given, many of which were obtained from density functional theory. The model provides a basis for predicting the transient response of III-V heterojunction bipolar transistors to pulsed neutron irradiation.« less

Computed tomography landmark-based semi-automated mesh morphing and mapping techniques: generation of patient specific models of the human pelvis without segmentation.

PubMed

Salo, Zoryana; Beek, Maarten; Wright, David; Whyne, Cari Marisa

2015-04-13

Current methods for the development of pelvic finite element (FE) models generally are based upon specimen specific computed tomography (CT) data. This approach has traditionally required segmentation of CT data sets, which is time consuming and necessitates high levels of user intervention due to the complex pelvic anatomy. The purpose of this research was to develop and assess CT landmark-based semi-automated mesh morphing and mapping techniques to aid the generation and mechanical analysis of specimen-specific FE models of the pelvis without the need for segmentation. A specimen-specific pelvic FE model (source) was created using traditional segmentation methods and morphed onto a CT scan of a different (target) pelvis using a landmark-based method. The morphed model was then refined through mesh mapping by moving the nodes to the bone boundary. A second target model was created using traditional segmentation techniques. CT intensity based material properties were assigned to the morphed/mapped model and to the traditionally segmented target models. Models were analyzed to evaluate their geometric concurrency and strain patterns. Strains generated in a double-leg stance configuration were compared to experimental strain gauge data generated from the same target cadaver pelvis. CT landmark-based morphing and mapping techniques were efficiently applied to create a geometrically multifaceted specimen-specific pelvic FE model, which was similar to the traditionally segmented target model and better replicated the experimental strain results (R(2)=0.873). This study has shown that mesh morphing and mapping represents an efficient validated approach for pelvic FE model generation without the need for segmentation. Copyright © 2015 Elsevier Ltd. All rights reserved.

[Recent advances in treatment of aseptic femoral shaft nonunion].

PubMed

Zhang, Wei; Chen, Hua; Tang, Peifu

2018-05-01

To review the recent advances in treatment of aseptic femoral shaft nonunion. The clinical studies about the treatments of aseptic femoral shaft nonunion in recent years were widely reviewed and analyzed. There are several surgical methods for aseptic femoral shaft nonunion. Due to uncertain clinical outcome, dynamization of nail should be carefully selected. The exchange nailing is suitable for the hypertrophic nonunion of the isthmal femoral shaft fracture. The exchange lateral plating is suitable for nonunion with obvious malformation. However, wave plate or dual plate should be chosen when the bone nonuinon is combined with the medial defect. The augmentation plating improves the success rate of nailing for femoral shaft nonunion, but it should be carefully selected for patients with obvious deformity or bone defect. Ilizarov technique is suitable for various bone nonunion, especially with complicated or large segmental bone defects. Induced membrane technique is also an important method for the treatment of bone nonunion with large bone defects. The clinical efficacy of the blocking screw remains to be supported by further evidence. Biological stimulants are mainly used for atrophic nonunion, and the clinical efficacy of them alone are still controversial. Due to lack of comparative studies between different surgical methods, the orthopedist should choose the appropriate treatment according to the individual situations of the patient and the types of bone nonunion.

The Pedicled Buccal Fat Pad: Anatomical Study of the New Flap for Skull Base Defect Reconstruction After Endoscopic Endonasal Transpterygoid Surgery

PubMed Central

Golbin, Denis A.; Lasunin, Nikolay V.; Cherekaev, Vasily A.; Polev, Georgiy A.

2016-01-01

Objectives To evaluate the efficacy and safety of using a buccal fat pad for endoscopic skull base defect reconstruction. Design Descriptive anatomical study with an illustrative case presentation. Setting Anatomical study was performed on 12 fresh human cadaver specimens with injected arteries (24 sides). Internal carotid artery was exposed in the coronal plane via the endoscopic transpterygoid approach. The pedicled buccal fat pad was used for reconstruction. Participants: 12 human cadaver head specimens; one patient operated using the proposed technique. Main outcome measures: Proximity of the buccal fat pad flap to the defect, compliance of the flap, comfort and safety of harvesting procedure, and compatibility with the Hadad–Bassagasteguy nasoseptal flap. Results: Harvesting procedure was performed using anterior transmaxillary corridor. The pedicled buccal fat pad flap can be used to pack the sphenoid sinus or cover the internal carotid artery from cavernous to upper parapharyngeal segment. Conclusion The buccal fat pad can be safely harvested through the same approach without external incisions and is compliant enough to conform to the skull base defect. The proposed pedicled flap can replace free abdominal fat in central skull base reconstruction. The volume of the buccal fat pad allows obliteration of the sphenoid sinus or upper parapharyngeal space. PMID:28180047

Coordination of Fictive Motor Activity in the Larval Zebrafish Is Generated by Non-Segmental Mechanisms

PubMed Central

Wiggin, Timothy D.; Peck, Jack H.; Masino, Mark A.

2014-01-01

The cellular and network basis for most vertebrate locomotor central pattern generators (CPGs) is incompletely characterized, but organizational models based on known CPG architectures have been proposed. Segmental models propose that each spinal segment contains a circuit that controls local coordination and sends longer projections to coordinate activity between segments. Unsegmented/continuous models propose that patterned motor output is driven by gradients of neurons and synapses that do not have segmental boundaries. We tested these ideas in the larval zebrafish, an animal that swims in discrete episodes, each of which is composed of coordinated motor bursts that progress rostrocaudally and alternate from side to side. We perturbed the spinal cord using spinal transections or strychnine application and measured the effect on fictive motor output. Spinal transections eliminated episode structure, and reduced both rostrocaudal and side-to-side coordination. Preparations with fewer intact segments were more severely affected, and preparations consisting of midbody and caudal segments were more severely affected than those consisting of rostral segments. In reduced preparations with the same number of intact spinal segments, side-to-side coordination was more severely disrupted than rostrocaudal coordination. Reducing glycine receptor signaling with strychnine reversibly disrupted both rostrocaudal and side-to-side coordination in spinalized larvae without disrupting episodic structure. Both spinal transection and strychnine decreased the stability of the motor rhythm, but this effect was not causal in reducing coordination. These results are inconsistent with a segmented model of the spinal cord and are better explained by a continuous model in which motor neuron coordination is controlled by segment-spanning microcircuits. PMID:25275377

A new medical image segmentation model based on fractional order differentiation and level set

NASA Astrophysics Data System (ADS)

Chen, Bo; Huang, Shan; Xie, Feifei; Li, Lihong; Chen, Wensheng; Liang, Zhengrong

2018-03-01

Segmenting medical images is still a challenging task for both traditional local and global methods because the image intensity inhomogeneous. In this paper, two contributions are made: (i) on the one hand, a new hybrid model is proposed for medical image segmentation, which is built based on fractional order differentiation, level set description and curve evolution; and (ii) on the other hand, three popular definitions of Fourier-domain, Grünwald-Letnikov (G-L) and Riemann-Liouville (R-L) fractional order differentiation are investigated and compared through experimental results. Because of the merits of enhancing high frequency features of images and preserving low frequency features of images in a nonlinear manner by the fractional order differentiation definitions, one fractional order differentiation definition is used in our hybrid model to perform segmentation of inhomogeneous images. The proposed hybrid model also integrates fractional order differentiation, fractional order gradient magnitude and difference image information. The widely-used dice similarity coefficient metric is employed to evaluate quantitatively the segmentation results. Firstly, experimental results demonstrated that a slight difference exists among the three expressions of Fourier-domain, G-L, RL fractional order differentiation. This outcome supports our selection of one of the three definitions in our hybrid model. Secondly, further experiments were performed for comparison between our hybrid segmentation model and other existing segmentation models. A noticeable gain was seen by our hybrid model in segmenting intensity inhomogeneous images.