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Sample records for head osteonecrosis model

  1. A new osteonecrosis animal model of the femoral head induced by microwave heating and repaired with tissue engineered bone

    PubMed Central

    Han, Rui; Geng, Chengkui; Wang, Yongnian; Wei, Lei

    2008-01-01

    The objective of this research was to induce a new animal model of osteonecrosis of the femoral head (ONFH) by microwave heating and then repair with tissue engineered bone. The bilateral femoral heads of 84 rabbits were heated by microwave at various temperatures. Tissue engineered bone was used to repair the osteonecrosis of femoral heads induced by microwave heating. The roentgenographic and histological examinations were used to evaluate the results. The femoral heads heated at 55°C for ten minutes showed low density and cystic changes in X-ray photographs, osteonecrosis and repair occurred simultaneously in histology at four and eight weeks, and 69% femoral heads collapsed at 12 weeks. The ability of tissue engineered bone to repair the osteonecrosis was close to that of cancellous bone autograft. The new animal model of ONFH could be induced by microwave heating, and the tissue engineering technique will provide an effective treatment. PMID:18956184

  2. Arthroplasty in Femoral Head Osteonecrosis

    PubMed Central

    Nam, Dong Cheol; Jung, Kwangyoung

    2014-01-01

    Osteonecrosis of the femoral head is a destructive joint disease requiring early hip arthroplasty. The polyethylene-metal design using a 22-mm femoral head component, introduced by Charnley in 1950, has been widely used for over half a century. Since then, different materials with the capacity to minimize friction between bearing surfaces and various cement or cementless insert fixations have been developed. Although the outcome of second and third generation designs using better bearing materials and technologies has been favorable, less favorable results are seen with total hip arthroplasty in young patients with osteonecrosis. Selection of appropriate materials for hip arthroplasty is important for any potential revisions that might become inevitable due to the limited durability of a prosthetic hip joint. Alternative hip arthroplasties, which include hemiresurfacing arthroplasty and bipolar hemiarthroplasty, have not been found to have acceptable outcomes. Metal-on-metal resurfacing has recently been suggested as a feasible option for young patients with extra physical demands; however, concerns about complications such as hypersensitivity reaction or pseudotumor formation on metal bearings have emerged. To ensure successful long-term outcomes in hip arthroplasty, factors such as insert stabilization and surfaces with less friction are essential. Understanding these aspects in arthroplasty is important to selection of proper materials and to making appropriate decisions for patients with osteonecrosis of the femoral head. PMID:27536561

  3. A canine model of osteonecrosis of the femoral head induced by MRI guided argon helium cryotherapy system

    PubMed Central

    Wang, Dong; Sun, Lixin; Zhang, Huawu; Jiang, Honglei; Liu, Ming; Tian, Jing; Hu, Na; Sun, Shui

    2015-01-01

    Objective: This study is to identify the reliability of osteonecrosis of the femoral head (ONFH) modeling established by MRI guided argon helium cryotherapy system in beagles. Methods: A total of 15 beagles were used to establish the ONFH model. The left femoral heads of the beagles received two cycles of argon helium freezing-thawing under MRI guidance and were considered as experimental group while the right femoral heads received only one cycle of argon helium freezing-thawing and were considered as the control group. X-ray, MRI, general shape and histological examinations were performed so as to identify the effect of modeling. Results: At 4 week after modeling, MRI showed obvious bilateral hip joint effusion and marked femoral head bone marrow high signal. At 8 week after surgery, abnormal signal appeared in bilateral femoral heads. T1WI showed irregular patchy low signal, T2WI showed irregular mixed signals and the joint capsule effusion showed long T1 and T2 changes. Twelve weeks after operation, T1WI showed a low signal strip with clear boundary and T2WI showed intermediate signal. The changes of the left femoral heads were significant while compared with those of the right sides. The lacunae rates of femoral heads in the experimental group at 4, 8, and 12 week after surgery (40.75 ± 3.77, 57.46 ± 4.01, 50.27 ± 2.98) were higher than those in control group (30.08 ± 3.61, 49.43 ± 2.82, 40.56 ± 2.73). Conclusion: Canine model of ONFH was successfully established using an argon helium cryotherapy system. PMID:26550205

  4. Management of femoral head osteonecrosis: Current concepts

    PubMed Central

    Tripathy, Sujit Kumar; Goyal, Tarun; Sen, Ramesh Kumar

    2015-01-01

    Osteonecrosis of femoral head (ONFH) is a disabling condition of young individuals with ill-defined etiology and pathogenesis. Remains untreated, about 70-80% of the patients progress to secondary hip arthritis. Both operative and nonoperative treatments have been described with variable success rate. Early diagnosis and treatment is the key for success in preserving the hip joint. Once femoral head collapses (>2 mm) or if there is secondary degeneration, hip conservation procedures become ineffective and arthroplasty remains the only better option. We reviewed 157 studies that evaluate different treatment modalities of ONFH and then a final consensus on treatment was made. PMID:25593355

  5. Vascular deprivation-induced necrosis of the femoral head of the rat. An experimental model of avascular osteonecrosis in the skeletally immature individual or Legg-Perthes disease.

    PubMed

    Norman, D; Reis, D; Zinman, C; Misselevich, I; Boss, J H

    1998-06-01

    The blood supply of rats' femoral heads was severed by cutting the ligamentum teres and stripping the periostium. Histologically, necrosis of the marrow was apparent on the 2nd postoperative day, necrosis of the bone on the 5th postoperative day and fibrous ingrowth on the 7th postoperative day. During the following 5 weeks, progressive resorption of the intertrabecular necrotic debris and necrotic bony trabeculae and subchondral bone plate and, concurrently, appositional and intramembranous new bone formation resulted in remodeling of the femoral heads. In 2 of 7 femoral heads, replacement of the necrotic bone by viable bone was complete at the 42-day postoperative interval. Also, the articular cartilage of the deformed and flattened femoral heads was undergoing degenerative changes. Reduplicating the pathogenically inferred clinical settings of blood supply deprivation, it is proposed that this model, in a small laboratory animal, satisfies the requirements sought for preclinical studies of treatment modalities of avascular osteonecrosis in man.

  6. A novel animal model of osteonecrosis of the femoral head induced using a magnetic resonance imaging-guided argon-helium cryotherapy system

    PubMed Central

    WANG, DONG; WANG, GUOWEI; LIU, MING; SUN, LIXIN; ZONG, WEI; JIANG, HONGLEI; ZHANG, HUAWU; LI, HUIBO; GONG, JIANBAO; SUN, SHUI

    2014-01-01

    The aim of the present study was to establish a novel animal model of osteonecrosis of the femoral head (ONFH) using a magnetic resonance imaging (MRI)-guided argon-helium cryotherapy system. A total of 48 rabbits were used to generate the ONFH models. In group I, the left femoral head of the rabbits received two cycles of argon-helium freezing-thawing under MRI guidance, while in group II, the right femoral head of each rabbit received only one cycle of argon-helium freezing-thawing. X-ray and histological examinations were performed. The percentages of lacunae in the femoral heads of group I at weeks 4, 8 and 12 following surgery (49.75±3.17, 62.06±4.12 and 48.25±2.76%, respectively) were higher than those in group II (39.13±4.48, 50.69±3.84 and 37.50±3.86%, respectively). In addition, the percentage of empty lacunae in group I was 62.06% at week 8 following surgery. Therefore, an animal model of ONFH was successfully established using an argon-helium cryotherapy system. The percentage of empty lacunae in group I was higher than that in group II at weeks 4, 8 and 12 after surgery. PMID:24926337

  7. Knee loading protects against osteonecrosis of the femoral head by enhancing vessel remodeling and bone healing.

    PubMed

    Liu, Daquan; Li, Xinle; Li, Jie; Yang, Jing; Yokota, Hiroki; Zhang, Ping

    2015-12-01

    Osteonecrosis of the femoral head is a serious orthopedic problem. Moderate loads with knee loading promote bone formation, but their effects on osteonecrosis have not been investigated. Using a rat model, we examined a hypothesis that knee loading enhances vessel remodeling and bone healing through the modulation of the fate of bone marrow-derived cells. In this study, osteonecrosis was induced by transecting the ligamentum teres followed by a tight ligature around the femoral neck. For knee loading, 5 N loads were laterally applied to the knee at 15 Hz for 5 min/day for 5 weeks. Changes in bone mineral density (BMD) and bone mineral content (BMC) of the femur were measured by pDEXA, and ink infusion was performed to evaluate vessel remodeling. Femoral heads were harvested for histomorphometry, and bone marrow-derived cells were isolated to examine osteoclast development and osteoblast differentiation. The results showed that osteonecrosis significantly induced bone loss, and knee loading stimulated both vessel remodeling and bone healing. The osteonecrosis group exhibited the lowest trabecular BV/TV (p b 0.001) in the femoral head, and lowest femoral BMD and BMC (both p b 0.01). However, knee loading increased trabecular BV/TV (p b 0.05) as well as BMD (pb 0.05) and BMC (p b 0.01). Osteonecrosis decreased the vessel volume (pb 0.001), vessel number (pb 0.001) and VEGF expression (p b 0.01), and knee loading increased them (pb 0.001, pb 0.001 and p b 0.01). Osteonecrosis activated osteoclast development, and knee loading reduced its formation, migration, adhesion and the level of “pit” formation (pb 0.001, pb 0.01, pb 0.001 and pb 0.001). Furthermore, knee loading significantly increased osteoblast differentiation and CFU-F (both p b 0.001). A significantly positive correlation was observed between vessel remodeling and bone healing (both p b 0.01). These results indicate that knee loading could be effective in repair osteonecrosis of the femoral head in a rat

  8. Bilateral Osteonecrosis of the Femoral and Humeral Heads after Short Term Corticosteroid Therapy. A Case Study.

    PubMed

    El Gamal, Tarek Ahmed; El-Bakoury, Ahmed; Hawkins, Amanda; Ed AlTayeb Mussa, Moham; Er Ahmed Sweed, Tam; Eh Samir Ansara, Sam

    2016-03-23

    Steroid induced osteonecrosis is a devastating injury that usually requires rebuild of the joint, with the femoral and the humeral head being most commonly affected. Steroid therapy is the most common reported cause of atraumatic osteonecrosis. The Collaborative Osteonecrosis Group Study confirmed that steroids are the primary cause of multi-focal osteonecrosis in 91% of the cases. Osteonecrosis is considered multifocal when three or more joints are involved. We report a rare case of bilateral steroid-induced osteonecrosis of the proximal femora and humeri nine months after a short course of intravenous methylprednisolone for treatment of multiple myeloma. The relationship between development of osteonecrosis and corticosteroid treatment has been extensively investigated. Steroid therapy is the most common reported cause of atraumatic osteonecrosis. Multi-focal osteonecrosis should be highly suspected and thoroughly investigated in patients with persistent pain at typical sites after commencement of steroids.

  9. Current concepts on osteonecrosis of the femoral head

    PubMed Central

    Moya-Angeler, Joaquin; Gianakos, Arianna L; Villa, Jordan C; Ni, Amelia; Lane, Joseph M

    2015-01-01

    It is estimated that 20000 to 30000 new patients are diagnosed with osteonecrosis annually accounting for approximately 10% of the 250000 total hip arthroplasties done annually in the United States. The lack of level 1 evidence in the literature makes it difficult to identify optimal treatment protocols to manage patients with pre-collapse avascular necrosis of the femoral head, and early intervention prior to collapse is critical to successful outcomes in joint preserving procedures. There have been a variety of traumatic and atraumatic factors that have been identified as risk factors for osteonecrosis, but the etiology and pathogenesis still remains unclear. Current osteonecrosis diagnosis is dependent upon plain anteroposterior and frog-leg lateral radiographs of the hip, followed by magnetic resonance imaging (MRI). Generally, the first radiographic changes seen by radiograph will be cystic and sclerotic changes in the femoral head. Although the diagnosis may be made by radiograph, plain radiographs are generally insufficient for early diagnosis, therefore MRI is considered the most accurate benchmark. Treatment options include pharmacologic agents such as bisphosphonates and statins, biophysical treatments, as well as joint-preserving and joint-replacing surgeries. the surgical treatment of osteonecrosis of the femoral head can be divided into two major branches: femoral head sparing procedures (FHSP) and femoral head replacement procedures (FHRP). In general, FHSP are indicated at pre-collapse stages with minimal symptoms whereas FHRP are preferred at post-collapse symptomatic stages. It is difficult to know whether any treatment modality changes the natural history of core decompression since the true natural history of core decompression has not been delineated. PMID:26396935

  10. Current concepts on osteonecrosis of the femoral head.

    PubMed

    Moya-Angeler, Joaquin; Gianakos, Arianna L; Villa, Jordan C; Ni, Amelia; Lane, Joseph M

    2015-09-18

    It is estimated that 20000 to 30000 new patients are diagnosed with osteonecrosis annually accounting for approximately 10% of the 250000 total hip arthroplasties done annually in the United States. The lack of level 1 evidence in the literature makes it difficult to identify optimal treatment protocols to manage patients with pre-collapse avascular necrosis of the femoral head, and early intervention prior to collapse is critical to successful outcomes in joint preserving procedures. There have been a variety of traumatic and atraumatic factors that have been identified as risk factors for osteonecrosis, but the etiology and pathogenesis still remains unclear. Current osteonecrosis diagnosis is dependent upon plain anteroposterior and frog-leg lateral radiographs of the hip, followed by magnetic resonance imaging (MRI). Generally, the first radiographic changes seen by radiograph will be cystic and sclerotic changes in the femoral head. Although the diagnosis may be made by radiograph, plain radiographs are generally insufficient for early diagnosis, therefore MRI is considered the most accurate benchmark. Treatment options include pharmacologic agents such as bisphosphonates and statins, biophysical treatments, as well as joint-preserving and joint-replacing surgeries. the surgical treatment of osteonecrosis of the femoral head can be divided into two major branches: femoral head sparing procedures (FHSP) and femoral head replacement procedures (FHRP). In general, FHSP are indicated at pre-collapse stages with minimal symptoms whereas FHRP are preferred at post-collapse symptomatic stages. It is difficult to know whether any treatment modality changes the natural history of core decompression since the true natural history of core decompression has not been delineated.

  11. Hip replacement in femoral head osteonecrosis: current concepts

    PubMed Central

    Scaglione, Michelangelo; Fabbri, Luca; Celli, Fabio; Casella, Francesco; Guido, Giulio

    2015-01-01

    Summary Osteonecrosis of the femoral head is a destructive disease that usually affects young adults with high functional demands and can have devastating effects on hip joint. The treatment depends on extent and location of the necrosis lesion and on patient’s factors, that suggest disease progression, collapse probability and also implants survival. Non-idiopathic osteonecrosis patients had the worst outcome. There is not a gold standard treatment and frequently it is necessary a multidisciplinary approach. Preservation procedures of the femoral head are the first choice and can be attempted in younger patients without head collapse. Replacement procedure remains the main treatment after failure of preserving procedures and in the late-stage ONFH, involving collapse of the femoral head and degenerative changes to the acetabulum. Resurfacing procedure still has good results but the patient selection is a critical factor. Total hip arthroplasties had historically poor results in patients with osteonecrosis. More recently, reports have shown excellent results, but implant longevity and following revisions are still outstanding problems. PMID:27134633

  12. Osteonecrosis

    MedlinePlus

    Avascular necrosis; Bone infarction; Ischemic bone necrosis; AVN; Aseptic necrosis ... Osteonecrosis occurs when part of the bone does not get blood and dies. After a while, the bone can collapse. If osteonecrosis is not treated, the joint deteriorates, leading ...

  13. Effects of sodium ferulate on preventing steroid-induced femoral head osteonecrosis in rabbits

    PubMed Central

    Tian, Lei; Dang, Xiao-qian; Wang, Chun-sheng; Yang, Pei; Zhang, Chen; Wang, Kun-zheng

    2013-01-01

    The aim of this study is to investigate the effects and possible mechanisms of sodium ferulate (SF) on anti-apoptosis in steroid-induced femoral head osteonecrosis in rabbits. Japanese white rabbits were randomly divided into three groups (control group, treatment group, and model group), each with 24 rabbits. The model and treatment groups were first injected with an intravenous dose of horse serum, 10 ml/kg, three weeks later with an intravenous dose of 7.5 ml/kg, and two weeks later with an intramuscular dose of methylprednisolone, 45 mg/kg, three times in order to establish rabbit models of osteonecrosis. Concurrently, the treatment group was injected with intravenous doses of SF 20 mg/kg for two weeks, once per day. Three time points, Weeks 2, 4, and 8, were selected after modeling was completed. Osteonecrosis was verified by histopathology with haematoxylin-eosin (HE) staining. The apoptosis rate of osteonecrosis was observed by terminal deoxynucleotidyl transferase dUTP nick end labeling (TUNEL) assay. The apoptosis expressions of caspase-3 and Bcl-2 were analyzed by immunohistochemistry and Western blot. The rabbit models of osteonecrosis were successfully established and observed by HE staining. SF was effective in intervening in apoptosis and decreasing the apoptosis rate in femoral head necrosis by the immunohistochemistry and TUNEL assay (P<0.01). Western blot analysis indicated that there were statistical significances in the protein levels of caspase-3 and Bcl-2 (P<0.01). SF has a protective effect by reducing the incidence of early steroid-induced femoral head necrosis in rabbits, effectively intervening in apoptosis through decreasing caspase-3 expression and up-regulating Bcl-2 expression. PMID:23645179

  14. Modified Transtrochanteric Rotational Osteotomy for Femoral Head Osteonecrosis

    PubMed Central

    Abbas, Azlina Amir; Hur, Chang Ich; Cho, Sang Gwon; Lee, Jin Ho

    2008-01-01

    Osteonecrosis of the femoral head is a disabling condition affecting young patients and treatment of the disease in these patients is variable. We retrospectively reviewed 39 patients (43 hips) in whom a modified transtrochanteric rotational osteotomy was performed for osteonecrosis. The minimum followup was 24 months (mean, 36.6 months; range, 24–52 months). The mean patient age was 34.3 years (range, 20–51 years). Based on the ARCO classification, 17 hips were classified as Stage II and 26 as Stage III. We performed rotational osteotomy alone in 15 cases, in combination with simple bone grafting in three, and in combination with muscle-pedicle-bone grafting in 25. Sixteen of 17 ARCO Stage II cases and 24 of 26 ARCO Stage III cases had no progression of collapse or lesion size; three hips progressively collapsed. Of the 40 hips without progression the Harris hip score improved from a mean 70 to 92 points at final followup, as did the range of motion of the hip. Modified transtrochanteric rotational osteotomy is an effective method for delaying the progression of collapse in the treatment of selected cases of osteonecrosis of the femoral head. Level of Evidence: Level IV, therapeutic study. See the Guidelines for Authors for a complete description of levels of evidence. PMID:18350346

  15. Osteonecrosis of the Femoral Head in an Adolescent on Long-Term Inhalational Corticosteroids

    PubMed Central

    Ballock, R. Tracy

    2017-01-01

    A relationship between the development of osteonecrosis of the femoral head and systemic corticosteroids has been well established in the literature, particularly in adults. However, the link between osteonecrosis and inhaled corticosteroids is less researched and understood. We report an usual case report of a 10-year-old male who developed ipsilateral femoral head osteonecrosis after long-term inhalational corticosteroid and intermittent short courses of oral steroid usage with a unique presentation and delayed diagnosis. PMID:28337355

  16. Association of toll-like receptor 4 signaling pathway with steroid-induced femoral head osteonecrosis in rats.

    PubMed

    Tian, Lei; Zhou, Dong-Sheng; Wang, Kun-Zheng; Zhang, Wei; Shi, Zhi-Bin; Fan, Li-Hong; Sun, Shui

    2014-10-01

    Osteonecrosis of the femoral head is frequently observed in patients treated with excessive corticosteroids. However, the pathogenesis of corticosteroid-induced osteonecrosis remains unclear. The purpose of this study was to investigate the role of Toll-like receptor 4 (TLR4) signaling pathway in steroid-induced femoral head osteonecrosis in rats. Male Sprague-Dawley rats were injected intramuscularly with 20 mg/kg methylprednisolone (MP) for 8 weeks, twice per week. The animals were sacrificed at 2, 4 and 8 weeks after the last MP injection, respectively, and then allocated to the 2-, 4- and 8-week model groups (n=24 each). Rats in the control group (n=12) were not given any treatment. Histopathological analysis was performed and the concentration of tartrate-resistant acid phosphatase (TRAP) in plasma was determined. The activation of osteoclasts in the femoral head was assessed by TRAP staining. The expression of TLR4, MyD88, TRAF6 and NF-κB p65 that are involved in TLR4 signaling, and MCP-1 production were detected by using real-time PCR (RT-PCR) and Western blotting. The results showed that the osteonecrosis in the femoral head was clearly observed and the concentration of TRAP in the plasma was increased in the model rats. The femoral head tissues in MP-treated rats were positive for TRAP and the intensity of TRAP staining was greater in MP-treated rats than in control rats. As compared with the control group, the mRNA expression of TLR4 signaling-related factors was enhanced significantly at 4 and 8 weeks, and the protein levels of these factors increased significantly with time. It was concluded that MP could induce the femoral head osteonecrosis in rats, which was associated with osteoclast activation via the TLR4 signaling pathway. These findings suggest that TLR4 signaling pathway plays a pivotal role in the pathogenesis of steroid-induced osteonecrosis.

  17. Acute BMP2 upregulation following induction of ischemic osteonecrosis in immature femoral head.

    PubMed

    Kamiya, Nobuhiro; Shafer, Sasha; Oxendine, Ila; Mortlock, Douglas P; Chandler, Ronald L; Oxburgh, Leif; Kim, Harry K W

    2013-03-01

    Juvenile ischemic osteonecrosis of the femoral head (IOFH) is one of the most serious hip conditions causing the femoral head deformity. Little is known about BMP signaling following ischemic osteonecrosis. In this study, we found acute BMP2 upregulation in the femoral head cartilage 24h after ischemic induction using our immature pig IOFH model. Similarly, in our ischemic osteonecrosis mouse model, BMP2 expression and BMP signaling were enhanced in the articular cartilage surrounding the necrotic bone. BMP2 was increased in cartilage explants and primary chondrocytes under hypoxia (1% O(2)) compared with normoxia (21% O(2)). Addition of the hypoxia inducible factor 1 (HIF1) activator DFO significantly increased BMP2 while HIF1 silencing (siHIF1) only partially reduced BMP2, suggesting other mechanisms of BMP2 upregulation being present. Hypoxia is known to induce the production of free oxygen radicals, which are converted to hydrogen peroxide (H(2)O(2)) by superoxide dismutase 2 (SOD2). As an alternative mechanism, we investigated the effect of H(2)O(2)/SOD2 production on BMP2 upregulation. Chondrocytes produced more H(2)O(2) under hypoxia than normoxia. H(2)O(2) addition to the chondrocyte culture also significantly increased BMP2 expression. SOD2 was also dramatically increased in the ischemic pig cartilage at 24h following surgery and in primary chondrocytes/cartilage explants culture under hypoxia. SOD2 protein addition to the chondrocyte culture significantly increased BMP2. Moreover, DFO significantly increased SOD2 while HIF1 silencing only partially reduced SOD2. These results suggest that the acute BMP2 response of chondrocytes to ischemic osteonecrosis is more dominantly through the H(2)O(2) production and only partly through the HIF1 pathway.

  18. Can local Erythropoietin administration enhance bone regeneration in osteonecrosis of femoral head?

    PubMed

    Bakhshi, Hooman; Rasouli, Mohammad R; Parvizi, Javad

    2012-08-01

    Osteonecrosis of femoral head (ONFH) is a challenging disease. Regardless of underlying causes, the ultimate result in all cases is disruption of femoral head blood supply. Once the disease starts, it is progressive in 80% of cases. Since the majority of the affected individuals are young, every effort should be focused on preserving the patients own femoral head. These years, the role of angiogenic growth factors has been investigated with promising results in animal models of ONFH. Erythropoietin (EPO) is a well known hormone that has been used in treatment of chronic anemia for many years with few side effects. Considering the angiogenic properties of EPO, we hypothesize that local delivery of recombinant human EPO during core decompression will enhance bone regeneration in ONFH. In this way we also can avoid systemic side effects of EPO.

  19. Hypoxia-Inducible Factor Prolyl Hydroxylase Inhibitor Prevents Steroid-Associated Osteonecrosis of the Femoral Head in Rabbits by Promoting Angiogenesis and Inhibiting Apoptosis

    PubMed Central

    Fan, Lihong; Li, Jia; Yu, Zefeng; Dang, Xiaoqian; Wang, Kunzheng

    2014-01-01

    The purpose of this study was to investigate the preventive effect of ethyl 3,4-dihydroxybenzoate(EDHB) on steroid-associated femoral head osteonecrosis(ONFH) in a rabbit model. New Zealand white rabbits were randomly divided into two groups (prevention group and model group), each containing 24 rabbits. Osteonecrosis was induced by lipopolysaccharide(LPS) combined with methylprednisolone(MPS). The prevention group received an intraperitoneal injection of EDHB at 50 mg/kg body weight every other day starting three days before establishing rabbit models of osteonecrosis, for a total of nine doses. Osteonecrosis was verified by haematoxylin-eosin (HE) staining. The expression of HIF-1α and VEGF was analyzed by immunohistochemistry. Angiogenesis, apoptosis and microstructural parameters were also analyzed. The rabbit models of osteonecrosis were successfully established and observed by HE staining. Histopathological observations indicated that EDHB reduced the rate of empty lacunae and the incidence of osteonecrosis. Immunohistochemical staining for HIF-1α and VEGF suggested that EDHB therapy inhibited degradation of HIF-1α and promoted expression of VEGF. Ink artery infusion angiography and microvessel density analysis revealed that there were more microvessels in the prevention group than in the model group. The TUNEL apoptosis assay suggested that EDHB intervention could reduce the number of apoptotic cells in avascular osteonecrosis of the femoral head. Micro-CT scanning indicated that the treatment group had better microstructural parameters than the model group. EDHB prevents steroid-associated osteonecrosis of the femoral head in rabbits by promoting angiogenesis and inhibiting apoptosis of bone cells and hematopoietic tissue. PMID:25244080

  20. Porous tantalum rods for treating osteonecrosis of the femoral head.

    PubMed

    Liu, Z H; Guo, W S; Li, Z R; Cheng, L M; Zhang, Q D; Yue, D B; Shi, Z C; Wang, B L; Sun, W; Zhang, N F

    2014-10-20

    This study evaluated the outcomes of using porous tantalum rods for the treatment of osteonecrosis of the femoral head (ONFH). We performed core decompression and inserted porous tantalum implants in 149 patients (168 consecutive hips) with ONFH. Hips had large (65), medium (64), or small (39) lesions; 63 lesions were lateral, 68 were central, and 35 were medial. Conversion to total hip arthroplasty (THA) was the end point of this survey. A total of 130 cases (138 hips) were followed. The mean follow-up time was 38.46 ± 5.76 months; 43 hips (31%) were converted to or needed THA. Of the 43 hips requiring THA, 33 had large lesions, including 1 medial, 3 central, and 29 lateral lesions; 9 had medium, lateral lesions, and 1 hip had a small, lateral lesion. Bone grafting was used in 59 hips, with 3 hips failing; 40 of 79 hips without bone grafts failed. The sum distances between the tops of the rods and the lateral lesion boundaries (SDTL, mm) were measured in anteroposterior and lateral radiographs. In the failure and spared groups, the average SDTLs were 7.65 ± 2.759 and 0.83 ± 2.286 mm, respectively. The survival of porous tantalum rods used for treating early-stage ONFH was affected by the size and location of the lesion, whether or not a bone graft was used, as well as the distance between top of the rod and the lateral boundary of the lesion.

  1. Salvianolic acid B prevents steroid-induced osteonecrosis of the femoral head via PPARγ expression in rats

    PubMed Central

    Li, Shuangqing; Wang, Juan

    2017-01-01

    Salvianolic acid B (Sal B) is a water-soluble phenolic compound derived from Salvia Miltiorrhiza. Recent studies show Sal B has a clear function of anti-cerebral ischemia injury, which is closely related to antioxidation, free radical scavenging, neuroprotection and the blood brain barrier. The aim of the present study was to verify whether Sal B prevents steroid-induced osteonecrosis of the femoral head and to investigate its underlying pharmacological mechanisms. Steroid-induced osteonecrosis rat models were established to evaluate the effects of Sal B on osteonecrotic changes and repair processes. The use of Sal B improved steroid-induced histopathological scores and inhibited osteoclast differentiation in rats. Notably, Sal B induced bone marrow-derived mesenchymal stem cells into osteogenesis. Moreover, Sal B treatment suppressed peroxisome proliferator-activated receptor (PPAR)γ and AP2 protein expression levels and increased runt-related transcription factor 2 and Collagen I protein expression levels in steroid-induced rats. osteocalcin and alkaline phosphatase content in steroid-induced rats was enhanced by treatment with Sal B. These results suggest that Sal B prevents steroid-induced osteonecrosis of the femoral head via PPARγ expression in rats. The present pilot study provides a brief insight into the effect of Sal B on steroid-induced osteonecrosis. PMID:28352346

  2. Attrition tendinitis of long head of biceps brachii in relation to humeral head osteonecrosis: case report.

    PubMed

    Wiesler, Ethan R; Sarlikiotis, Thomas; Mavrogenis, Andreas F; Kokkalis, Zinon T

    2013-01-01

    This case report identifies a 41-year-old male patient who developed anterior shoulder pain in the setting of humeral head osteonecrosis. As a consequence of the cartilage degeneration, multiple loose bodies formed and migrated into the bicipital tendon sheath, causing attrition tendinitis, which was a feature of the clinical presentation. The patient was treated by a combination of arthroscopic glenohumeral joint debridement and open tenodesis of the biceps using a suture anchor. Follow-up revealed asymptomatic shoulder function by 18 months. This is the first report in the literature of bicipital tendinitis in the context of avascular necrosis of the shoulder.

  3. Management of osteonecrosis of the femoral head: A novel technique

    PubMed Central

    Samy, Ahmed M

    2016-01-01

    Background: Osteonecrosis of the femoral head (ONFH) is a debilitating disease in orthopedics, frequently progressing to femoral head collapse and osteoarthritis. It is thought to be a multifactorial disease. ONFH ultimately results in femoral head collapse in 75–85% of untreated patients. Total hip arthroplasty (THA) yields satisfactory results in the treatment of the end stage of the disease. However, disease typically affects males between the ages of 20 and 40 years and joint replacement is not the ideal option for younger patients. Recently, mesenchymal stem cells and platelet rich plasma (PRP) have been used as an adjunct to core decompression to improve clinical success in the treatment of precollapse hips. Materials and Methods: A prospective study of 40 hips in 30 patients was done. There were 19 males and 11 females with a mean age 36.7 ± 6.93 years. The indication for the operation was restricted primarily to modified Ficat stages IIb and III. 16 hips (40%) had stage IIb and 24 hips (60%) had stage III ONFH. The period of follow up ranged between 36–50 months with a mean 41.4 ± 3.53 months. All patients were assessed clinically during pre- and post-operative period according to the Harris Hip Score (HHS), Visual Analog Score (VAS) and radiologically by X-rays. Magnetic resonance imaging (MRI) was done preoperatively to confirm the diagnosis and every 6 months postoperatively for assessment of healing. The operative procedure include removal of necrotic area with drilling then the cavity was filled with a composite of bone graft mixed with PRP. Results: The mean HHS improved from 46.0 ± 7.8 preoperatively to 90.28 ± 19 at the end of followup (P < 0.0001). The mean values of VAS were 78 ± 21 and 35 ± 19 at preoperatively period and final followup, respectively, with an average reduction of 43 points. Conclusion: We found that the use of PRP with collagen sheet can increase the reparable capacity after drilling of necrotic segment in stage IIb and

  4. Steroid-induced femoral head osteonecrosis in immune thrombocytopenia treatment with osteochondral autograft transplantation.

    PubMed

    Fotopoulos, Vasileios Ch; Mouzopoulos, George; Floros, Themistoklis; Tzurbakis, Matthaios

    2015-09-01

    Osteonecrosis of the femoral head is a devastating complication of steroid administration and has rarely been observed in the treatment of immune thrombocytopenia. The treatment of osteochondral defects in advanced stages of avascular necrosis (AVN), characterized by collapse of the subchondral bone, remains an unsolved burden in orthopedic surgery. In this report, we present a case of a 19-year-old female that was admitted in the Emergency Department with walking disability and painful hip joint movement due to steroid-induced femoral head osteonecrosis. Two years before she was diagnosed with immune thrombocytopenia, for which she received pulse steroid therapy with high dose of dexamethasone and underwent a splenectomy. This case report is the first to describe the use of osteochondral autograft transplantation as a treatment of steroid-induced AVN of the femoral head due to immune thrombocytopenia at the age of 19 years with very good clinical and radiological results 3 years postoperatively.

  5. Asparaginase Potentiates Glucocorticoid-Induced Osteonecrosis in a Mouse Model.

    PubMed

    Liu, Chengcheng; Janke, Laura J; Kawedia, Jitesh D; Ramsey, Laura B; Cai, Xiangjun; Mattano, Leonard A; Boyd, Kelli L; Funk, Amy J; Relling, Mary V

    2016-01-01

    Osteonecrosis is a common dose-limiting toxicity of glucocorticoids. Data from clinical trials suggest that other medications can increase the risk of glucocorticoid-induced osteonecrosis. Here we utilized a mouse model to study the effect of asparaginase treatment on dexamethasone-induced osteonecrosis. Mice receiving asparaginase along with dexamethasone had a higher rate of osteonecrosis than those receiving only dexamethasone after 6 weeks of treatment (44% vs. 10%, P = 0.006). Similarly, epiphyseal arteriopathy, which we have shown to be an initiating event for osteonecrosis, was observed in 58% of mice receiving asparaginase and dexamethasone compared to 17% of mice receiving dexamethasone only (P = 0.007). As in the clinic, greater exposure to asparaginase was associated with greater plasma exposure to dexamethasone (P = 0.0001). This model also recapitulated other clinical risk factors for osteonecrosis, including age at start of treatment, and association with the systemic exposure to dexamethasone (P = 0.027) and asparaginase (P = 0.036). We conclude that asparaginase can potentiate the osteonecrotic effect of glucocorticoids.

  6. Vitamin K2 Prevents Glucocorticoid-induced Osteonecrosis of the Femoral Head in Rats.

    PubMed

    Zhang, Yue-Lei; Yin, Jun-Hui; Ding, Hao; Zhang, Wei; Zhang, Chang-Qing; Gao, You-Shui

    2016-01-01

    Glucocorticoid medication is one of the most common causes of atraumatic osteonecrosis of the femoral head (ONFH), and vitamin K2 (VK2) has been shown to play an important and beneficial role in bone metabolism. In this study, we hypothesized that VK2 could decrease the incidence of glucocorticoid-induced ONFH in a rat model. Using in vitro studies, we investigated how bone marrow-derived stem cells in the presence of methylprednisolone proliferate and differentiate, specifically examining osteogenic-related proteins, including Runx2, alkaline phosphatase and osteocalcin. Using in vivo studies, we established glucocorticoid-induced ONFH in rats and investigated the preventive effect of VK2. We employed micro-CT scanning, angiography of the femoral head, and histological and immunohistochemical analyses, which demonstrated that VK2 yielded beneficial effects for subchondral bone trabecula. In conclusion, VK2 is an effective antagonist for glucocorticoid on osteogenic progenitors. The underlying mechanisms include acceleration of BMSC propagation and promotion of bone formation-associated protein expression, which combine and contribute to the prevention of glucocorticoid-induced ONFH in rats.

  7. Extracorporeal shockwave therapy in osteonecrosis of femoral head

    PubMed Central

    Zhang, Qingyu; Liu, Lihua; Sun, Wei; Gao, Fuqiang; Cheng, Liming; Li, Zirong

    2017-01-01

    Abstract Background: Osteonecrosis is an incapacitating disorder with high morbidity. Though extracorporeal shockwave therapy (ESWT) provides a noninvasive treatment option, controversial subjects still exist about its effectiveness, indications, and mechanism of action. Methods: An electronic databases search was performed using PubMed, Embase, and the Cochrane library to collect clinical trials, case reports, and cases series on this topic and then useful data were extracted and appraised by experienced clinicians. We evaluated the quality of included evidences by using the Oxford Centre for evidence-based medicine (EBM) Levels of Evidence. Results: A total of 17 articles including 2 case reports, 9 open label trials, 2 cohorts, and 6 randomized controlled trials were considered to be eligible for this systematic review. Visual analog scale (VAS), Harris hip scores, and the imaging results were the frequently-used outcome estimates of included studies. Conclusion: By systematically analyzing these evidences, we could conclude that ESWT could act as a safe and effective method to improve the motor function and relieve the pain of patients with osteonecrosis of femoral hip, especially those at early stage. Imaging revealed that bone marrow edema was significantly relieved, but the necrotic bone could not be reversed after ESWT. This technique could slow or even block the progression of ONFH and therefore reduce the demand for surgery. Collaboration with other conservative modalities would not improve the curative benefits of ESWT. Meanwhile, ONFH with various risk factors showed similar reaction to this noninvasive treatment method. However, these conclusions should be interpreted carefully for the low-quality of included publications and further studies are requisite to validate the effect of ESWT in ONFH. PMID:28121934

  8. [Avascular osteonecrosis of femoral head and neck in an AIDS patient].

    PubMed

    Villafañe, Maria F; Corti, Marcelo E; Candela, Miguel; Perez Bianco, Raul; Tezanos Pinto, Miguel

    2004-01-01

    Avascular osteonecrosis (AON) has increased in the last few years in patients infected with the human immunodeficiency virus type-1 (HIV-1). The most commonly affected bone is the femoral head and neck. Frequently these bilateral and clinical findings include moderate to severe pain and functional impotence of the affected joints. The etiology is multifactorial and highly active antiretroviral therapy (HAART) with protease inhibitors (PI) is probably related to its development. In the evolution, a total hip replacement may be needed. We present an hemophilic patient with AIDS, who developed a bilateral AON of the femoral head and neck during HAART.

  9. Osteonecrosis (Avascular Necrosis)

    MedlinePlus

    ... developing osteonecrosis. Electrical stimulation. A procedure in which electromagnetic fields are set up around the bones or ... hip joint. The femoral head often collapses in advanced osteonecrosis. Femur. The upper leg, or thigh, bone. ...

  10. Porous Tantalum Implant in Treating Osteonecrosis of the Femoral Head: Still a Viable Option?

    PubMed Central

    Ma, Jinhui; Sun, Wei; Gao, Fuqiang; Guo, Wanshou; Wang, Yunting; Li, Zirong

    2016-01-01

    The purpose of this study is to evaluate the survivorship and risk factors for radiographic progression and conversion to total hip arthroplasty (THA) after porous tantalum implant surgery in the treatment of osteonecrosis of the femoral head (ONFH). The study comprised 90 ONFH patients (104 consecutive hips) who were treated with a porous tantalum implant combined with bone grafting between June 2008 and December 2013. The patients were 19–61 years of age (mean age, 38 years). The mean follow-up was 42 months. The outcome measures included Harris hip score (HHS), radiographic outcome measures, and survivorship analysis with conversion to THA as the endpoint. The mean postoperative HHS was significantly lower than the mean preoperative HHS (P < 0.001). The Cox proportional hazards model showed that age and Association Research Circulation Osseous (ARCO) stage were independent risk factors for conversion to THA, while age, China-Japan Friendship Hospital (CJFH) type, and ARCO stage were independent risk factors for radiological progression. Ultimately, only 52.9% hips survived. Porous tantalum implant surgery combined with bone grafting is not a viable option for treating ONFH, especially in patients >35 years of age with preoperative ARCO stage III and CJFH type L3. PMID:27324659

  11. Bisphosphonate-modified gold nanoparticles: a useful vehicle to study the treatment of osteonecrosis of the femoral head

    NASA Astrophysics Data System (ADS)

    Fanord, Fedena; Fairbairn, Korie; Kim, Harry; Garces, Amanda; Bhethanabotla, Venkat; Gupta, Vinay K.

    2011-01-01

    Legg-Calvé-Perthes disease (LCPD) is a juvenile form of osteonecrosis of the femoral head that presents in children aged 2-14 years. To date, there is no effective medical therapy for treating LCPD largely due to an inability to modulate the repair process, including the predominance of bone resorption. This investigation aims to evaluate the feasibility of using gold nanoparticles (GNPs) that are surface modified with a bisphosphonate compound for the treatment of osteonecrosis at the cellular level. Studies have found osteoclast-mediated resorption to be a process that contributes significantly to the pathogenesis of femoral head deformities arising from Perthes disease. Our in vitro model was designed to elucidate the effect of alendronate-(a bisphosphonate) modified GNPs, on osteoclastogenesis and osteoclast function. RAW 264.7 macrophage cells were cultured with recombinant mouse receptor activator of NF-κB ligand (RANKL), which stimulates osteoclastogenesis, and were then treated with alendronate-modified GNPs for 24, 48, and 72 h. Cell proliferation, osteoclast function, and osteoclast morphology were evaluated by trypan blue dye exclusion assay, tartrate-resistant acid phosphatase (TRAP) staining, and transmission electron microscopy (TEM) imaging. Comparative studies were performed with GNPs that were only stabilized with citrate ions and with alendronate alone. Neither osteoclastogenesis nor osteoclast function were adversely affected by the presence of the citrate-GNP. Alendronate-modified GNPs had an enhanced effect on inducing osteoclast apoptosis and impairing osteoclast function when compared to unbound alendronate populations.

  12. Correlation Between Residual Displacement and Osteonecrosis of the Femoral Head Following Cannulated Screw Fixation of Femoral Neck Fractures.

    PubMed

    Wang, Chen; Xu, Gui-Jun; Han, Zhe; Jiang, Xuan; Zhang, Cheng-Bao; Dong, Qiang; Ma, Jian-Xiong; Ma, Xin-Long

    2015-11-01

    The aim of the study was to introduce a new method for measuring the residual displacement of the femoral head after internal fixation and explore the relationship between residual displacement and osteonecrosis with femoral head, and to evaluate the risk factors associated with osteonecrosis of the femoral head in patients with femoral neck fractures treated by closed reduction and percutaneous cannulated screw fixation.One hundred and fifty patients who sustained intracapsular femoral neck fractures between January 2011 and April 2013 were enrolled in the study. All were treated with closed reduction and percutaneous cannulated screw internal fixation. The residual displacement of the femoral head after surgery was measured by 3-dimensional reconstruction that evaluated the quality of the reduction. Other data that might affect prognosis were also obtained from outpatient follow-up, telephone calls, or case reviews. Multivariate logistic regression analysis was applied to assess the intrinsic relationship between the risk factors and the osteonecrosis of the femoral head.Osteonecrosis of the femoral head occurred in 27 patients (18%). Significant differences were observed regarding the residual displacement of the femoral head and the preoperative Garden classification. Moreover, we found more or less residual displacement of femoral head in all patients with high quality of reduction based on x-ray by the new technique. There was a close relationship between residual displacement and ONFH.There exists limitation to evaluate the quality of reduction by x-ray. Three-dimensional reconstruction and digital measurement, as a new method, is a more accurate method to assess the quality of reduction. Residual displacement of the femoral head and the preoperative Garden classification were risk factors for osteonecrosis of the femoral head. High-quality reduction was necessary to avoid complications.

  13. Treatment of osteonecrosis of the femoral head with vascularized bone grafting.

    PubMed

    Millikan, Patrick D; Karas, Vasili; Wellman, Samuel S

    2015-09-01

    Osteonecrosis of the femoral head (ONFH) is a challenging diagnosis for the patient and treating surgeon. Though its cause is poorly understood, several methods of surgical treatment exist and are performed with variable success. Vascularized bone grafting is one such treatment that attempts to restore viable bone, structural support, and blood supply to the avascular portion of the femoral head. This review summarizes the various approaches to this technique that have been proposed and put into practice. The cost effectiveness of these procedures, both in time and resources, has been evaluated and found to be favorable. The use of revascularization procedures, along with the introduction of other potentiating factors, may signal an exciting future for this debilitating disease process.

  14. Evaluation of the Squirrel Monkey (Saimiri sciureus) as an Experimental Animal Model for Dysbaric Osteonecrosis.

    DTIC Science & Technology

    1976-01-07

    Osteonecrosis , Squirrel monkeys, Dysbarism, Decompression AM STRACT (Coalftwo Af VOW0 df it 060006 Red AV Ihib 6 In an attempt to develop an animal model for...subclinical decomipression sickness was produced. No clinical, radiologic, or post-mortem evidence of osteonecrosis was discovered during either the 6...ANIMAL MODE[L FOR DYSBARIC OSTEONECROSIS Uwsimemnt Ctoilo Jamm L. Kuppwr, USAF VC Naval Medical Rearchh and Doevlwomfnt Commxw SM~~?000.OI .01 .7022 A

  15. Vitamin K2 Ameliorates Damage of Blood Vessels by Glucocorticoid: a Potential Mechanism for Its Protective Effects in Glucocorticoid-induced Osteonecrosis of the Femoral Head in a Rat Model

    PubMed Central

    Zhang, Yuelei; Yin, Junhui; Ding, Hao; Zhang, Changqing; Gao, You-Shui

    2016-01-01

    Glucocorticoid has been reported to decrease blood vessel number and harm the blood supply in the femoral head, which is recognized to be an important mechanism of glucocorticoid-induced osteonecrosis of the femoral head (ONFH). To prevent glucocorticoid-induced ONFH, medication that promotes both bone formation and angiogenesis would be ideal. Vitamin K2 has been revealed to play an important role in bone metabolism; however, few studies have focused on the effect of Vitamin K2 on new vascular formation. Thus, this study aimed to investigate whether Vitamin K2 promoted new blood vessel formation in the presence of glucocorticoids, both in vitro and in vivo. The effect of Vitamin K2 on viability, migration, in vitro tube formation, and VEGF, vWF, CD31, KDR, Flt and PDGFB in EAhy926 incubated with or without dexamethasone were elucidated. VEGF, TGF-β and BMP-2, angiogenesis-related proteins secreted by osteoblasts, were also detected in the osteoblast-like cell line of MG63. In addition, blood vessels of the femoral head in rats administered with or without methylprednisolone and Vitamin K2 were evaluated using angiography and CD31 staining. In vitro studies showed that Vitamin K2 significantly protected endothelial cells from dexamethasone-induced apoptosis, promoted endothelial cell migration and in vitro tube formation. Angiogenesis-related proteins both in EAhy926 and MG63 were also upregulated by Vitamin K2 when cotreated with dexamethasone. In vivo studies showed enhanced blood vessel volume and CD31-positive staining cells in rats cotreated with VK2 and methylprednisolone compared to rats treated with methylprednisolone only. Collectively, Vitamin K2 has the ability to promote angiogenesis in vitro and to ameliorate vessels of the femoral head in glucocorticoid-treated rats in vivo, indicating that Vitamin K2 is a promising drug that may be used to prevent steroid-induced ONFH. PMID:27313492

  16. A current review of non-vascularized bone grafting in osteonecrosis of the femoral head.

    PubMed

    Pierce, Todd P; Elmallah, Randa K; Jauregui, Julio J; Poola, Shiva; Mont, Michael A; Delanois, Ronald E

    2015-09-01

    Over the past three decades, non-vascularized bone grafts have been demonstrated to be viable treatments for pre- and early post-collapse osteonecrosis of the femoral head; however, there are limited reviews on this topic. Therefore, the purposes of this review are to (1) provide a summary of the different surgical techniques and their respective clinical outcomes and (2) evaluate new adjunct therapies. Originally, non-vascularized bone grafting was performed using the Phemister technique with varying results. More recently, newer techniques such as the lightbulb and trapdoor are used to place non-vascularized bone grafts with excellent results. The addition of various biological agents has demonstrated positive results; however, further studies are needed to confirm the best appropriate indications and to elucidate long-term results.

  17. [Is instillation of bone marrow stem cells at the time of core decompression useful for osteonecrosis of the femoral head?].

    PubMed

    Cabrolier, Jorge; Molina, Marcelo

    2016-03-24

    Osteonecrosis of the femoral head leads to degeneration of the head and finally to osteoarthritis of the hip. Decompression is the most widely used treatment, but its effectiveness is limited. It has been proposed instillation of stem cells in addition to decompression, would lead to better results. Searching in Epistemonikos database, which is maintained by screening 30 databases, we identified two systematic reviews including two randomized trials. We combined the evidence using meta-analysis and generated a summary of findings table following the GRADE approach. We concluded instillation of bone marrow stem cells at the time of core decompression probably slows progression to osteoarthritis of the hip in patients with osteonecrosis of the femoral head and might reduce the need of subsequent surgeries. It is unclear whether it has any effect on the functionality because the certainty of the evidence is very low.

  18. 3D segmentation and quantification of magnetic resonance data: application to the osteonecrosis of the femoral head

    NASA Astrophysics Data System (ADS)

    Klifa, Catherine S.; Lynch, John A.; Zaim, Souhil; Genant, Harry K.

    1999-05-01

    The general objective of our study is the development of a clinically robust three-dimensional segmentation and quantification technique of Magnetic Resonance (MR) data, for the objective and quantitative evaluation of the osteonecrosis (ON) of the femoral head. This method will help evaluate the effects of joint preserving treatments for femoral head osteonecrosis from MR data. The disease is characterized by tissue changes (death of bone and marrow cells) within the weight-bearing portion of the femoral head. Due to the fuzzy appearance of lesion tissues and their different intensity patterns in various MR sequences, we proposed a semi-automatic multispectral segmentation of MR data introducing data constraints (anatomical and geometrical) and using a classical K-means unsupervised clustering algorithm. The method was applied on ON patient data. Results of volumetric measurements and configuration of various tissues obtained with the semi- automatic method were compared with quantitative results delineated by a trained radiologist.

  19. Failed vascularized fibular graft in treatment of osteonecrosis of the femoral head. A histopathological analysis

    PubMed Central

    MELONI, MARIA CHIARA; HOEDEMAEKER, W. RUSSALKA; FORNASIER, VICTOR

    2016-01-01

    Purpose vascularized fibular grafting has been used to treat osteonecrosis of the femoral head in younger patients. Although the results described in the literature are promising, the failure rate is still significant, especially in steroid users. This study was undertaken to learn more, on a histopathological level, about the mechanism of vascularized fibular graft failure. Methods fifteen femoral heads removed at conversion to total hip arthroplasty were analyzed. The case load comprised 10 men and 5 women. They ranged in age from 28 to 39 years and had a median age of 35 years. The interval between the vascularized fibular implant procedure and the conversion to total hip arthroplasty ranged from 22 months to 30 months; the median interval was 26 months. All the patients were steroid users. The heads were sectioned and axial and coronal sections were taken and stained using the WHO method (hematoxylin, phloxine, saffron and Alcian green). A quantitative and qualitative analysis of graft-host interaction at the head (zone 1), neck (zone 2) and epiphysis (zone 3) was performed. Results all the specimens showed recognizable collapse of the articular surface over the area of necrosis. Thirteen femoral heads showed the presence of an osteochondral flap attached only at the margins of the area of avascular necrosis, and 10 of these 13 femoral heads also showed loss of the articulating surface with an ulcer crater corresponding to the exposed area of avascular necrosis. Conclusions vascularized fibular graft failure seems to be related to a negative effect of creeping substitution: the revascularization becomes a negative force as it supports unbalanced bone resorption, which, as is well known, is enhanced by corticosteroids. Clinical relevance creeping substitution is an undermining force in the repair and revascularization of the necrotic area in the femoral head. PMID:27386444

  20. Costo-osteochondral graft for post-traumatic osteonecrosis of the radial head in an adolescent boy.

    PubMed

    Iwai, S; Sato, K; Nakamura, T; Okazaki, M; Itoh, Y; Toyama, Y; Ikegami, H

    2011-01-01

    We present a case of post-traumatic osteonecrosis of the radial head in a 13-year-old boy which was treated with costo-osteochondral grafts. A satisfactory outcome was seen at a follow-up of two years and ten months. Although costo-osteochondral grafting has been used in the treatment of defects in articular cartilage, especially in the hand and the elbow, the extension of the technique to manage post-traumatic osteonecrosis of the radial head in a child has not previously been reported in the English language literature. Complete relief of pain was obtained and an improvement in the range of movement was observed. The long-term results remain uncertain.

  1. Primary epiphyseal arteriopathy in a mouse model of steroid-induced osteonecrosis.

    PubMed

    Janke, Laura J; Liu, Chengcheng; Vogel, Peter; Kawedia, Jitesh; Boyd, Kelli L; Funk, Amy J; Relling, Mary V

    2013-07-01

    Patients undergoing glucocorticoid therapy for a variety of disorders, including autoimmune diseases and hematological malignancies, are at risk of developing osteonecrosis. Despite extensive research in both patients and animal models, the underlying pathogenesis remains unclear. Proposed inciting mechanisms include intravascular thrombotic occlusion, marrow fat hypertrophy, osteocyte and/or endothelial cell apoptosis, hypercoagulability, and vasoconstriction of specific arteries and arterioles supplying bone. Our laboratory has developed a model of steroid-induced osteonecrosis in BALBcJ mice which reflects clinically relevant exposures to glucocorticoids in which treated mice develop osteonecrosis of the distal femoral epiphysis when administered 4 to 8 mg/L dexamethasone in drinking water for 6 weeks. We identified lesions in arterioles supplying this area, with the mildest occurring in knees without any evidence of osteonecrosis. However, arteriopathy was more common among mice that did versus did not develop osteonecrosis (P < 0.0001); in mice with osteonecrosis, the associated vessels showed transmural necrosis and thickening of the vessel wall progressing to the point of luminal obstruction. In the most severe cases of osteonecrosis, end-stage lesions consisted of fully occluded vessels with marrow and bone necrosis involving the entire epiphysis. We propose that a primary arteriopathy is the initiating event in the genesis of steroid-induced osteonecrosis and provides a basis for future investigation of this disease process.

  2. Preclinical Study of Cell Therapy for Osteonecrosis of the Femoral Head with Allogenic Peripheral Blood-Derived Mesenchymal Stem Cells

    PubMed Central

    Fu, Qiang; Tang, Ning-Ning; Zhang, Qian; Liu, Yi; Peng, Jia-Chen; Fang, Ning; Yu, Li-Mei; Liu, Jin-Wei

    2016-01-01

    Purpose To explore the value of transplanting peripheral blood-derived mesenchymal stem cells from allogenic rabbits (rPBMSCs) to treat osteonecrosis of the femoral head (ONFH). Materials and Methods rPBMSCs were separated/cultured from peripheral blood after granulocyte colony-stimulating factor mobilization. Afterwards, mobilized rPBMSCs from a second passage labeled with PKH26 were transplanted into rabbit ONFH models, which were established by liquid nitrogen freezing, to observe the effect of rPBMSCs on ONFH repair. Then, the mRNA expressions of BMP-2 and PPAR-γ in the femoral head were assessed by RT-PCR. Results After mobilization, the cultured rPBMSCs expressed mesenchymal markers of CD90, CD44, CD29, and CD105, but failed to express CD45, CD14, and CD34. The colony forming efficiency of mobilized rPBMSCs ranged from 2.8 to 10.8 per million peripheral mononuclear cells. After local transplantation, survival of the engrafted cells reached at least 8 weeks. Therein, BMP-2 was up-regulated, while PPAR-γ mRNA was down-regulated. Additionally, bone density and bone trabeculae tended to increase gradually. Conclusion We confirmed that local transplantation of rPBMSCs benefits ONFH treatment and that the beneficial effects are related to the up-regulation of BMP-2 expression and the down-regulation of PPAR-γ expression. PMID:27189298

  3. Influence of the volume of osteonecrosis on the outcome of core decompression of the femoral head

    PubMed Central

    Mazieres, B.; Marin, F.; Chiron, P.; Moulinier, L.; Amigues, J.; Laroche, M.; Cantagrel, A.

    1997-01-01

    OBJECTIVES—To assess the outcome of core decompression in the treatment of osteonecrosis of the femoral head related to the volume of necrotic bone measured according to a previously reported method.
METHODS—Twenty hips corresponding to strictly Ficat stage II underwent magnetic resonance imaging and the volume of necrotic bone was expressed as a percentage of the volume of the entire head measured on each slice. All hips underwent core decompression and the outcome was evaluated at 24 months. The primary evaluation criterion was radiological appearance: the outcome was considered as good if the hip remained stage II and poor if the disease progressed.
RESULTS—Twenty four months after core decompression, half the cases remained stable and in half the disease had progressed. Outcome seemed to be related to the volume of necrotic bone (average 22% in the good outcome group versus 45% in the poor outcome group (p = 0.0051)) and was independent of risk factors, age, and histological type.
CONCLUSIONS—The volume of necrotic bone should be taken into account in the evaluation of any treatment, bearing in mind that in more than one third of cases this volume will probably decrease, especially at the beginning of the disease process.

 PMID:9496156

  4. Atraumatic osteonecrosis of the humeral head after influenza A-(H1N1) v-2009 vaccination.

    PubMed

    Kuether, G; Dietrich, B; Smith, T; Peter, C; Gruessner, S

    2011-09-16

    In the recent pandemic influenza A-(H1N1) v-2009 vaccination campaign, adjuvanted vaccines have been used because of their antigen-sparing effect. According to available reports, the rate of severe vaccination reactions has not increased, as compared with previous seasonal influenza vaccinations. Here we describe an adult female patient who was vaccinated with an AS03 adjuvanted split-virus vaccine injected into the left arm. She experienced a prolonged and painful local reaction for 4 weeks. During this time, persistent incapacitating pain shifted into the left shoulder. Magnetic resonance imaging (MRI) at the injection site detected atraumatic humeral head osteonecrosis in conjunction with bursitis of the rotator cuff region. Clinical and laboratory examination revealed no other underlying disease. Using analgetic medication and physical therapy, resting pain completely remitted within the following 14 weeks. Pain on exertion declined within the following 6 months. Atraumatic osteonecrosis, a relatively rare disorder which initially presents non-specific clinical symptoms, has never been associated with parenteral influenza vaccination. Although the available data cannot establish a causal relationship, our patient's clinical course - with a continuous transition from increased local post-vaccination reactions to symptoms of a severe shoulder lesion with osteonecrosis - raises the question of a pathogenetic link. Considering the vascular pathogenesis of osteonecrosis, we hypothesize that our patient's enhanced local immunologic reaction may have led to regional vasculitis as the cause of bone destruction. As mild forms of osteonecrosis may have escaped previous clinical attention, it is the purpose of our report to increase awareness of this exceptional event as a possible side effect of parenteral adjuvanted vaccination.

  5. Experimental osteonecrosis: development of a model in rodents administered alendronate.

    PubMed

    Conte, Nicolau; Spolidorio, Luis Carlos; Andrade, Cleverton Roberto de; Esteves, Jônatas Caldeira; Marcantonio, Elcio

    2016-08-22

    The main objective of this study was to cause bisphosphonate-related osteonecrosis of the jaws to develop in a rodent model. Adult male Holtzman rats were assigned to one of two experimental groups to receive alendronate (AL; 1 mg/kg/week; n = 6) or saline solution (CTL; n = 6). After 60 days of drug therapy, all animals were subjected to first lower molar extraction, and 28 days later, animals were euthanized. All rats treated with alendronate developed osteonecrosis, presenting as ulcers and necrotic bone, associated with a significant infection process, especially at the inter-alveolar septum area and crestal regions. The degree of vascularization, the levels of C-telopeptide cross-linked collagen type I and bone-specific alkaline phosphatase, as well as the bone volume were significantly reduced in these animals. Furthermore, on radiographic analysis, animals treated with alendronate presented evident sclerosis of the lamina dura of the lower first molar alveolar socket associated with decreased radiographic density in this area. These findings indicate that the protocol developed in the present study opens new perspectives and could be a good starting model for future property design.

  6. Potential diagnostic role of diffusion tensor imaging in early-stage osteonecrosis of the femoral head

    PubMed Central

    Min, Hongwei; Xu, Feng; Gu, Rui; Han, Xinzuo; Wang, Anqing; Liu, Kemin

    2016-01-01

    The present study aimed to explore the potential diagnostic role of diffusion tensor magnetic resonance imaging (DTI) in the early stage of modified corticosteroid-induced osteonecrosis of the femoral head (ONFH). A total of 20 beagles were randomly classified (1:1) into either an experimental group (LM), which were intramuscularly injected with lipopolysaccharide (LPS) and methylprednisolone (MPS) on three consecutive days, or control (CON) group, which were injected with saline. Magnetic resonance imaging (MRI) and DTI were performed at pre-induction and 8 and 12 weeks post-induction. Apparent diffusion coefficient (ADC) values in the range of interest in the femoral head were quantified using DTI. Proximal femora were examined for ONFH at 8 and 12 weeks. The results demonstrated that ONFH developed in four beagles at 8 weeks and in six beagles at 12 weeks, whereas no ONFH was detected in the CON group. No abnormalities were detected by MRI and DTI, and no mortality occurred. In beagles with ONFH in the LM group, the ADC values were 4.7±0.2×10−4 and 4.8±0.3×10−4 mm2/sec at 8 and 12 weeks, respectively, which were significantly increased compared with the CON group (2.5±0.3×10−4 and 2.4±0.3×10−4 mm2, respectively) and the LM group without ONFH (2.6±0.4×10−4 and 2.4±0.3×10−4 mm2, respectively) (P<0.05). The results of the present study indicated that intramuscular injection of LPS and MPS may lead to early-stage ONFH in beagles. As such, the detection of locally elevated ADC values in the femoral head may aid in the early diagnosis of ONFH. PMID:27882161

  7. Bilateral non-traumatic aseptic osteonecrosis in the femoral head. An experimental study of incidence

    SciTech Connect

    Hauzeur, J.P.; Pasteels, J.L.; Orloff, S.

    1987-10-01

    Thirty-five patients who were seen with non-traumatic aseptic osteonecrosis of the femoral head were included in a study of the contralateral hip to evaluate the incidence of bilateral disease. We used not only conventional radiography and scintigraphy but also measurement of intramedullary pressure and core biopsy. Pain was caused by 14.3 per cent of the contralateral hips, a lesion was demonstrated on plain radiographs in 51.4 per cent, and increased isotopic uptake was seen in 31.4 per cent. Histological study of specimens obtained by osteomedullary biopsy (after special procedure) showed bilateral necrosis in 88.5 per cent of the patients. After a mean follow-up of thirty-four months, only one of nine hips that were painless and had negative radiographic and isotopic findings, but had positive findings on biopsy, became painful and radiographically positive. The intramedullary pressure in the intertrochanteric area was recorded in each hip, and no correlation was found with the radiographic stage or with pain.

  8. The role of hypercoagulability in the development of osteonecrosis of the femoral head

    PubMed Central

    Lykissas, Marios G.; Gelalis, Ioannis D.; Kostas-Agnantis, Ioannis P.; Vozonelos, Georgios; Korompilias, Anastasios V.

    2012-01-01

    Despite the large number of the outstanding researches, pathogenesis of osteonecrosis remains unknown. During the last decades the hypothesis that increased intravascular coagulation may be the pathogenetic mechanism which leads to osteonecrosis is gaining constantly support. Both primary factors of hyper-coagulability, such as resistance to activated protein C, protein C and protein S deficiency, low levels of tissue plasminogen activator, high levels of plasminogen activator inhibitor, von Willebrand factor, lipoprotein (a), and secondary factors of hypercoagulability with factors potentially activating intravascular coagulation, such as pregnancy, antiphospholipid antibodies, systemic lupus erythematosus, hemoglobinopathies and sickle cell disease, and hemato-oncologic diseases are discussed in this article. Although coagulation abnormalities in patients with hip osteonecrosis might represent increased risk factors for the development of bone necrosis by predisposing the patient to thromboembolic phenomena, further investigation is needed to indicate the definite correlation between factors leading to increased intravascular coagulation and pathogenesis of osteonecrosis. PMID:22802985

  9. The effect of deferoxamine on angiogenesis and bone repair in steroid-induced osteonecrosis of rabbit femoral heads.

    PubMed

    Li, Jia; Fan, Lihong; Yu, Zefeng; Dang, Xiaoqian; Wang, Kunzheng

    2015-02-01

    In this study, we examined whether local deferoxamine (DFO) administration can promote angiogenesis and bone repair in steroid-induced osteonecrosis of the femoral head (ONFH). Steroid-induced ONFH was induced in 65 mature male New Zealand white rabbits by methylprednisolone in combination with lipopolysaccharide. Six weeks later, the rabbits received no treatment (model group, N = 15), bilateral core decompression (CD group, N = 20) or CD in combination with local DFO administration (DFO group, N = 20). Six weeks after the surgery, vascularization in the femoral head was evaluated by ink artery infusion angiography and immunohistochemical staining for von Willebrand Factor (vWF). Bone repair was assessed by histologic analysis and micro-computed tomography (micro-CT). Immunohistochemical staining was performed to analyze the expression of vascular endothelial growth factor (VEGF), hypoxia-inducible factor-1α (HIF-1α), bone morphogenetic protein-2 (BMP-2), and osteocalcin (OCN). Ink artery infusion angiography and microvessel analysis by immuohistochemical staining for vWF showed more blood vessels in the DFO group than other groups. The expression of HIF-1α, VEGF, BMP-2, and OCN, indicated by immunohistochemical staining, was higher in the DFO group compared with other groups. Micro-CT scanning results indicated that the DFO group had larger volume of newly formed bone than the CD group. This work indicated that local DFO administration improved angiogenesis and bone repair of early stage ONFH in rabbit model, and it may offer an efficient, economic, and simple therapy for early stage ONFH.

  10. Vascularized bone grafting fixed by biodegradable magnesium screw for treating osteonecrosis of the femoral head.

    PubMed

    Zhao, Dewei; Huang, Shibo; Lu, Faqiang; Wang, Benjie; Yang, Lei; Qin, Ling; Yang, Ke; Li, Yangde; Li, Weirong; Wang, Wei; Tian, Simiao; Zhang, Xiuzhi; Gao, Wenbin; Wang, Zongpu; Zhang, Yu; Xie, Xinhui; Wang, Jiali; Li, Junlei

    2016-03-01

    Hip-preserving surgery with vascularized bone graft implantation has been widely practiced in treating osteonecrosis of the femoral head (ONFH). However, the current approach presents a drawback, in which the implanted bone graft without screw fixation may slip or exhibit a certain degree of displacement postoperatively. This study was designed to investigate the application potential of biodegradable magnesium (Mg) screws for the fixation of vascularized bone graft in ONFH patients. Forty-eight patients were randomly divided into two groups: the Mg screw group (vascularized bone grafting fixed by Mg screws) and the control group (vascularized bone grafting without fixation). During 12 month follow-up period after surgery, treatment outcomes in patients were assessed by multiple imaging techniques including x-ray and computed tomography (CT) scanning as well as functional recovery Harris hip score (HHS). The temporal changes in serum levels of Mg, Ca, and P as well as in vivo degradation rate of Mg screws were determined. The absence of potential adverse effects induced by degradation products from Mg screws on surrounding bone tissue was validated via CT imaging analysis. HHS was significantly improved in the Mg screw group when compared to the control group. X-ray imaging analysis showed that the screw shape did not show significant alteration due to the diameter of Mg screws measured with approximate 25% reduction within 12 months post-surgically. The postoperative serum levels of Ca, Mg, and P, which are relevant for liver and kidney function, were all within normal physiological range in all patients of both groups. The use of biodegradable Mg screws may provide a promising bone graft-screw fixation route in treating ONFH and present considerable potential for orthopedic applications.

  11. Curative effect and safety of vascularized fibula grafting in renal transplant recipients with osteonecrosis of the femoral head: three case reports.

    PubMed

    Guo, Y J; Jin, D X; Zhang, C Q; Chen, S B; Sheng, J G; Lee, H S; Zhang, K G; Zeng, B F

    2009-11-01

    Osteonecrosis of the femoral head is a common and severe complication after renal transplantation. It is characterized by deterioration of hip joint function, which impairs quality of life. We present 3 renal transplant case reports of patients with osteonecrosis of the femoral head who underwent free vascularized fibular grafting at our hospital. Follow-up was from 1(1/2) to 2 years. All 3 patients exhibited good recovery with substantial improvement in joint function. Intraoperative and postoperative findings demonstrated the safety of this surgical procedure.

  12. Exosomes from Human Synovial-Derived Mesenchymal Stem Cells Prevent Glucocorticoid-Induced Osteonecrosis of the Femoral Head in the Rat

    PubMed Central

    Guo, Shang-Chun; Tao, Shi-Cong; Yin, Wen-Jing; Qi, Xin; Sheng, Jia-Gen; Zhang, Chang-Qing

    2016-01-01

    Osteonecrosis of the femoral head (ONFH) represents a debilitating complication following glucocorticoid (GC)-based therapy. Synovial-derived mesenchymal stem cells (SMSCs) can exert protective effect in the animal model of GC-induced ONFH by inducing cell proliferation and preventing cell apoptosis. Recent studies indicate the transplanted cells exert therapeutic effects primarily via a paracrine mechanism and exosomes are an important paracrine factor that can be directly used as therapeutic agents for tissue engineering. Herein, we provided the first demonstration that the early treatment of exosomes secreted by human synovial-derived mesenchymal stem cells (SMSC-Exos) could prevent GC-induced ONFH in the rat model. Using a series of in vitro functional assays, we found that SMSC-Exos could be internalized into bone marrow derived stromal cells (BMSCs) and enhance their proliferation and have anti-apoptotic abilities. Finally, SMSC-Exos may be promising for preventing GC-induced ONFH. PMID:27766040

  13. Bilateral Idiopathic Osteonecrosis of the Femoral Head: A Case Report With an Emphasis on Differential Diagnosis, Imaging, and Treatment

    PubMed Central

    Battaglia, Patrick J.; Gliedt, Jordan; McDaniel, Courtney; Kettner, Norman

    2014-01-01

    Objective The purpose of this case report is to describe a patient with bilateral idiopathic osteonecrosis of the femoral head (ONFH), provide a discussion of differential diagnosis for anterior hip pain, imaging, and treatment recommendations for ONFH. Clinical features A 34-year-old man was initially treated by a chiropractic physician for low back pain. At the end of a three week trial of care, the patient’s low back pain resolved. However, he reported a new complaint of mild left anterior hip stiffness. After re-examination, a homecare exercise program was prescribed. The patient returned 1 month later with substantial left anterior hip pain and walked with a noticeable limp. Radiography of the left hip demonstrated advanced ONFH. Magnetic resonance imaging of both hips demonstrated the extent of involvement of the left hip while incidentally revealing ONFH on the right. Intervention and Outcome A total hip arthroplasty was performed on the left hip and the right hip is being monitored without intervention. Conclusion Osteonecrosis of the femoral head is a challenging clinical problem with non-specific and wide-ranging signs and symptoms requiring clinicians to engage a cautious and comprehensive differential diagnosis. Prompt recognition ensures that appropriate treatment can be initiated in a timely manner and optimal patient outcomes achieved. PMID:25225469

  14. Dimethyloxaloylglycine increases bone repair capacity of adipose-derived stem cells in the treatment of osteonecrosis of the femoral head

    PubMed Central

    Zhu, Zhen-Hong; Song, Wen-Qi; Zhang, Chang-Qing; Yin, Ji-Min

    2016-01-01

    Mesenchymal stem cells have been widely studied to promote local bone regeneration of osteonecrosis of the femoral head (ONFH). Previous studies observed that dimethyloxaloylglycine (DMOG) enhanced the angiogenic and osteogenic activity of mesenchymal stem cells by activating the expression of hypoxia inducible factor-1α (HIF-1α), thereby improving the bone repair capacity of mesenchymal stem cells. In the present study, it was investigated whether DMOG could increase the bone repair capacity of adipose-derived stem cells (ASCs) in the treatment of ONFH. Western blot analysis was performed to detect HIF-1α protein expression in ASCs treated with different concentrations of DMOG. The results showed DMOG enhanced HIF-1α expression in ASCs in a dose-dependent manner at least for 7 days. Furthermore, DMOG-treated ASCs were transplanted into the necrotic area of a rabbit model of ONFH to treat the disease. Four weeks later, micro-computed tomography (CT) quantitative analysis showed that 58.8±7.4% of the necrotic area was regenerated in the DMOG-treated ASCs transplantation group, 45.5±3.4% in normal ASCs transplantation group, 25.2±2.8% in only core decompression group and 10.6±2.6% in the untreated group. Histological analysis showed that transplantation of DMOG-treated ASCs clearly improved the bone regeneration of the necrotic area compared with the other three groups. Micro-CT and immunohistochemical analysis demonstrated the revasculation of the necrotic area were also increased significantly in the DMOG-treated ASC group compared with the control groups. Thus, it is hypothesized that DMOG could increase the bone repair capacity of ASCs through enhancing HIF-1α expression in the treatment of ONFH. PMID:27882083

  15. Avascular osteonecrosis of the femoral head in three West African HIV-infected adults with heterozygous sickle cell disease.

    PubMed

    Eholié, Serge P; Ouiminga, Mariama; Ehui, Eboi; Nzunetu, Gustave; Ouattara, Songda I; Konan, Alexis V; Anglaret, Xavier; Bissagnéné, Emmanuel

    2009-01-01

    Three men (aged 33, 44 and 45 years, CD4(+) T-cell nadir 86 cells/mm(3), 99 cells/mm(3) and 12 cells/mm(3), respectively) were admitted to the Department of Infectious Diseases (Treichville Hospital, Abidjan, Côte d'Ivoire) for hip pain and impaired mobility. Their last available CD4(+) T-cell counts were 243 cells/mm(3), 245 cells/mm(3) and 8 cells/mm(3), respectively. They had all received antiretroviral therapy for >4 years, including lopinavir/ritonavir for >8 months. The other risk factors were hypertriglyceridaemia (n=3), smoking addiction (n=2), alcohol consumption (n=2) and lipodystrophy (n=1). All three patients had heterozygous haemoglobin AS sickle cell disease (percentage of haemoglobin S 41%, 45% and 50%, respectively). The diagnosis of avascular osteonecrosis of the femoral head (unilateral n=2 and bilateral n=1) was documented by CT scan. Only one patient underwent surgical arthroplasty. In resource-limited settings, avascular osteonecrosis is uneasy to diagnose and unlikely to be appropriately treated. Physicians should be aware of its symptoms and risk factors, including HIV infection and antiretroviral therapy. Future studies should explore whether these risk factors might include haemoglobin AS sickle cell disease, a common trait in the West African general population.

  16. Local Administration of Bisphosphonate-soaked Hydroxyapatite for the Treatment of Osteonecrosis of the Femoral Head in Rabbit

    PubMed Central

    Ma, Jin-Hui; Guo, Wan-Shou; Li, Zi-Rong; Wang, Bai-Liang

    2016-01-01

    Background: Systemic administration of bisphosphonates has shown promising results in the treatment of osteonecrosis of the femoral head (ONFH). However, few studies have evaluated the efficacy of local zoledronate (ZOL) administration in the treatment of ONFH. The purpose of this study was to investigate whether local administration of bisphosphonate-soaked hydroxyapatite (HA) could improve bone healing in an experimental rabbit model of ONFH. Methods: This experimental study was conducted between October 2014 and June 2015. Forty-five rabbits underwent simulated ONFH surgery. Immediately following surgery, they were divided into three groups: model (untreated, n = 15), HA (treated with HA alone, n = 15), and HA + ZOL (treated with HA soaked in a low-dose ZOL solution, n = 15). Histological, immunohistochemical, and quantitative analyses were performed to evaluate bone formation and resorption 2, 4, and 8 weeks after surgery. Results: Gross bone matrix and hematopoietic tissue formation were observed in the HA + ZOL group 4 weeks after surgery. The immunohistochemical staining intensities for 5-bromodeoxyuridine, runt-related transcription factor 2, osteocalcin, osteopontin, and osteoprotegerin were significantly higher in the HA + ZOL group than that in the model (P < 0.001, P < 0.001, P < 0.001, P < 0.001, and P = 0.018, respectively) and HA groups (P = 0.003, P = 0.049, P < 0.001, P = 0.020, and P = 0.019, respectively), whereas receptor activator of the nuclear factor-κB ligand staining intensity was significantly lower in the HA + ZOL group than that in the model and HA groups (P = 0.029 and P = 0.015, respectively) 4 weeks after surgery. No significant differences in bone formation or bone resorption marker expression were found between the three groups 2 or 8 weeks after surgery (P > 0.05). Conclusions: Local administration of HA soaked in a low-dose ZOL solution increased new bone formation while inhibiting bone resorption in an animal model of ONFH

  17. Therapeutic effect of minimally invasive decompression combined with impaction bone grafting on osteonecrosis of the femoral head.

    PubMed

    Zhang, Hong-Jun; Liu, You-Wen; Du, Zhi-Qian; Guo, Huili; Fan, Ke-Jie; Liang, Guo-Hui; Liu, Xing-Cai

    2013-12-01

    The aim of this study was to observe the therapeutic effect of minimally invasive decompression combined with impaction bone grafting on osteonecrosis of the femoral head. A total of 67 patients underwent minimally invasive lightbulb decompression combined with impaction bone grafting. The therapeutic effect was evaluated according to Harris scores, and fluoroscopic and magnetic resolution imaging results at different time points. The Harris score was significantly increased after operation. The fineness rate was 85.4%. Postoperative disease progression was found in nine patients with the progression rate of 14.63%. The average necrotic area percentage was noticeably reduced 6 months, 1 year, and 2 years after operation. The one-year postoperative percentage showed a significant difference compared with the preoperative one. Minimally invasive lightbulb decompression combined with impaction bone grafting can achieve a satisfactory curative effect on ONFH. This method has the advantages of small trauma, thorough decompression, and good bone implantation.

  18. Exosomes Secreted from Human-Induced Pluripotent Stem Cell-Derived Mesenchymal Stem Cells Prevent Osteonecrosis of the Femoral Head by Promoting Angiogenesis

    PubMed Central

    Liu, Xiaolin; Li, Qing; Niu, Xin; Hu, Bin; Chen, Shengbao; Song, Wenqi; Ding, Jian; Zhang, Changqing; Wang, Yang

    2017-01-01

    Background: Local ischemia is the main pathological performance in osteonecrosis of the femoral head (ONFH). There is currently no effective therapy to promote angiogenesis in the femoral head. Recent studies revealed that exosomes secreted by induced pluripotent stem cell-derived mesenchymal stem cells (iPS-MSC-Exos) have great therapeutic potential in ischemic tissues, but whether they could promote angiogenesis in ONFH has not been reported, and little is known regarding the underlying mechanism. Methods: iPS-MSC-Exos were intravenously injected to a steroid-induced rat osteonecrosis model. Samples of the femoral head were obtained 3 weeks after all the injections. The effects were assessed by measuring local angiogenesis and bone loss through histological and immunohistochemical (IHC) staining, micro-CT and three-dimensional microangiography. The effects of exosomes on endothelial cells were studied through evaluations of proliferation, migration and tube-forming analyses. The expression levels of angiogenic related PI3K/Akt signaling pathway of endothelial cells were evaluated following stimulation of iPS-MSC-Exos. The promoting effects of exosomes were re-evaluated following blockade of PI3K/Akt. Results: The in vivo study revealed that administration of iPS-MSC-Exos significantly prevented bone loss, and increased microvessel density in the femoral head compared with control group. We found that iPS-MSC-Exos significantly enhanced the proliferation, migration and tube-forming capacities of endothelial cells in vitro. iPS-MSC-Exos could activate PI3K/Akt signaling pathway in endothelial cells. Moreover, the promoting effects of iPS-MSC-Exos were abolished after blockade of PI3K/Akt on endothelial cells. Conclusions: Our findings suggest that transplantation of iPS-MSC-Exos exerts a preventative effect on ONFH by promoting local angiogenesis and preventing bone loss. The promoting effect might be attributed to activation of the PI3K/Akt signaling pathway on

  19. Glucocorticoid-induced osteonecrosis.

    PubMed

    Weinstein, Robert S

    2012-04-01

    Awareness of the need for prevention of glucocorticoid-induced fractures is growing, but glucocorticoid administration is often overlooked as the most common cause of nontraumatic osteonecrosis. Glucocorticoid-induced osteonecrosis develops in 9-40% of patients receiving long-term therapy although it may also occur with short-term exposure to high doses, after intra-articular injection, and without glucocorticoid-induced osteoporosis. The name, osteonecrosis, is misleading because the primary histopathological lesion is osteocyte apoptosis. Apoptotic osteocytes persist because they are anatomically unavailable for phagocytosis and, with glucocorticoid excess, decreased bone remodeling retards their replacement. Glucocorticoid-induced osteocyte apoptosis, a cumulative and unrepairable defect, uniquely disrupts the mechanosensory function of the osteocyte-lacunar-canalicular system and thus starts the inexorable sequence of events leading to collapse of the femoral head. Current evidence indicates that bisphosphonates may rapidly reduce pain, increase ambulation, and delay joint collapse in patients with osteonecrosis.

  20. Clinical outcomes of osteonecrosis of the femoral head after autologous bone marrow stem cell implantation: a meta-analysis of seven case-control studies.

    PubMed

    Yuan, Heng-Feng; Zhang, Jing; Guo, Chang-An; Yan, Zuo-Qin

    2016-02-01

    The purpose of this study was to evaluate the clinical outcomes of osteonecrosis of the femoral head after autologous bone marrow stem cell implantation. We searched the PubMed, Embase and Web of Science databases and included all case-control trials that reported on the clinical outcomes of osteonecrosis progression, incidence of total hip arthroplasty and improvement in Harris hip scores. Overall, seven case-control trials were included. Compared with the controls, patients treated with the bone marrow stem cells implantation treatment showed improved clinical outcomes with delayed osteonecrosis progression (odds ratio = 0.17, 95% CI: 0.09 - 0.32; p <0.001), a lower total hip arthroplasty incidence (odds ratio = 0.30, 95% CI: 0.12 - 0.72; p <0.01) and increased Harris hip scores (mean difference = 4.76, 95% CI: 1.24 - 8.28; p<0.01). The heterogeneity, publication bias, and sensitivity analyses showed no statistical difference significant differences between studies. Thus, our study suggests that autologous bone marrow stem cells implantation has a good therapeutic effect on osteonecrosis of the femoral, resulting in beneficial clinical outcomes. However, trials with larger sample sizes are needed to confirm these findings.

  1. Microstructure and Nanomechanical Properties of Single Trabecular Bone in Different Regions of Osteonecrosis of the Femoral Head.

    PubMed

    Wang, Cheng; Wang, Yu; Meng, Haoye; Gou, Wenlong; Yuan, Xueling; Xu, Xiaolong; Wang, Aiyuan; Guo, Quanyi; Peng, Jiang; Lu, Shibi

    2016-03-01

    This study aimed to compare the microstructure and nanomechanical properties of single trabecular bone in different regions of osteonecrosis of the femoral head. Osteonecrotic femoral heads were taken from 20 patients undergoing total hip arthroplasties between 2011 and 2014. Following incision, resin was embedded and polished, and divided into four regions according to the type of pathologic change; i.e., subchondral bone, and necrotic, sclerotic, and healthy regions. Indents from a single trabecular bone of each region were randomly selected to undergo nanoindentation. The results are (1) The elastic modulus and degree of hardness were significantly elevated in the sclerotic region, but there were no differences in necrotic and subchondral bone regions compared with healthy regions. (2) The elastic modulus and hardness of the single trabecular bone were significantly greater in central versus edge regions (for all regions). The conclusions are (1) The mechanical properties of single bone trabeculae were not markedly altered in the necrotic region. (2) The elastic modulus and degree of hardness increased significantly between the edge and central regions, regardless of whether the bone was normal or osteonecrotic.

  2. A single-nucleotide polymorphism in MMP9 is associated with decreased risk of steroid-induced osteonecrosis of the femoral head

    PubMed Central

    Jin, Tianbo; Zhao, Zhenqun; Bai, Rui; Xue, Huiqin; Chen, Junyu; Sun, Mingqi; Zhang, Xiyang; Wang, Guoqiang; Wang, Jianzhong

    2016-01-01

    Osteonecrosis of the femoral head (ONFH) is a common hip joint disease, and steroid-induced ONFH accounts for a large number of cases. Here, we examined eight previously-identified single-nucleotide polymorphisms (SNPs) in the MPP2 and MPP9 genes of 285 steroid-induced ONFH patients and 507 healthy controls from northern China to determine whether these SNPs were associated with the risk of developing steroid-induced ONFH. Chi-squared tests and genetic model and haplotype analyses were used to evaluate associations. The rs2274755 SNP in MMP9 was associated with a decreased risk of steroid-induced ONFH in the allele, dominant, and additive models. Additionally, the “CGC” MMP9 haplotype was associated with a 0.69-fold decrease in the risk of steroid-induced ONFH. Although additional, larger population-based studies are needed to confirm these findings, our results reveal for the first time an association between a MMP9 SNP at the rs2274755 locus and a decreased risk of steroid-induced ONFH in a northern Chinese population. PMID:27637086

  3. Comprehensive Genome-Wide Transcriptomic Analysis of Immature Articular Cartilage following Ischemic Osteonecrosis of the Femoral Head in Piglets

    PubMed Central

    Adapala, Naga Suresh; Kim, Harry K. W.

    2016-01-01

    Objective Ischemic osteonecrosis of the femoral head (ONFH) in piglets results in an ischemic injury to the immature articular cartilage. The molecular changes in the articular cartilage in response to ONFH have not been investigated using a transcriptomic approach. The purpose of this study was to perform a genome-wide transcriptomic analysis to identify genes that are upregulated in the immature articular cartilage following ONFH. Methods ONFH was induced in the right femoral head of 6-week old piglets. The unoperated femoral head was used as the normal control. At 24 hours (acute ischemic-hypoxic injury), 2 weeks (avascular necrosis in the femoral head) and 4 weeks (early repair) after surgery (n = 4 piglets/time point), RNA was isolated from the articular cartilage of the femoral head. A microarray analysis was performed using Affymetrix Porcine GeneChip Array. An enrichment analysis and functional clustering of the genes upregulated due to ONFH were performed using DAVID and STRING software, respectively. The increased expression of selected genes was confirmed by a real-time qRTPCR analysis. Results Induction of ONFH resulted in the upregulation of 383 genes at 24 hours, 122 genes at 2 weeks and 124 genes at 4 weeks compared to the normal controls. At 24 hours, the genes involved in oxidoreductive, cell-survival, and angiogenic responses were significantly enriched among the upregulated genes. These genes were involved in HIF-1, PI3K-Akt, and MAPK signaling pathways. At 2 weeks, secretory and signaling proteins involved in angiogenic and inflammatory responses, PI3K-Akt and matrix-remodeling pathways were significantly enriched. At 4 weeks, genes that represent inflammatory cytokines and chemokine signaling pathways were significantly enriched. Several index genes (genes that are upregulated at more than one time point following ONFH and are known to be important in various biological processes) including HIF-1A, VEGFA, IL-6, IL6R, IL-8, CCL2, FGF2, TGFB2

  4. High triglyceride is a risk factor for silent osteonecrosis of the femoral head in systemic lupus erythematosus.

    PubMed

    Kuroda, Takeshi; Tanabe, Naohito; Wakamatsu, Ayako; Takai, Chinatsu; Sato, Hiroe; Nakatsue, Takeshi; Wada, Yoko; Nakano, Masaaki; Narita, Ichiei

    2015-12-01

    The purpose of this study was to clarify the factors related to silent osteonecrosis of the femoral head (ONFH) in patients with systemic lupus erythematosus (SLE). Seventy-eight patients with SLE were selected on the basis of having been newly diagnosed and requiring high-dose prednisolone, including pulse therapy with methylprednisolone, as the initial treatment. All the patients initially underwent MRI at 3 months after the start of corticosteroid treatment to detect any early changes in the femoral head. These examinations were then performed again 3 months later. Laboratory parameters were evaluated at the start of steroid treatment and at 1 month thereafter. By 3 months after the start of corticosteroid treatment, silent ONFH was diagnosed by MRI in 21 patients (26.9 %), being bilateral in 11 patients and unilateral in 10. The occurrence of silent ONFH was not related to SLE disease activity index, serological activity, or renal function; it was also unrelated to body mass index (BMI), body surface area (BSA), and the initial dose of prednisolone per unit body weight. However, the total cholesterol level at 4 weeks after the start of steroid treatment tended to be higher in patients with silent ONFH. Patients with a higher triglyceride level showed a significantly higher frequency of silent ONFH both before (p = 0.002) and 4 weeks after (p = 0.036) steroid initiation.A high triglyceride level is an important risk factor for silent ONFH in patients with SLE, and large-scale epidemiologic surveys of such early events are needed in this patient population.

  5. Recombinant Human Bone Morphogenetic Protein-2 in Debridement and Impacted Bone Graft for the Treatment of Femoral Head Osteonecrosis

    PubMed Central

    Gao, Fuqiang; Shi, Zhencai; Zhang, Qidong; Guo, Wanshou

    2014-01-01

    The purpose of this study was to compare the clinical outcomes of impacted bone graft with or without recombinant human bone morphogenetic protein-2 (rhBMP-2) for osteonecrosis of the femoral head (ONFH). We examined the effect of bone-grafting through a window at the femoral head-neck junction, known as the “light bulb” approach, for the treatment of ONFH with a combination of artificial bone (Novobone) mixed with or without rhBMP-2. A total of 42 patients (72 hips) were followed-up from 5 to 7.67 years (average of 6.1 years). The patients with and without BMP were the first group (IBG+rhBMP-2) and the second group (IBG), respectively. The clinical effectiveness was evaluated by Harris hip score (HHS). The radiographic follow-up was evaluated by pre-and postoperative X-ray and CT scan. Excellent, good, and fair functions were obtained in 36, 12, and 7 hips, respectively. The survival rate was 81.8% and 71.8% in the first and second group, respectively. However, the survival rate was 90.3% in ARCO stage IIb, c, and only 34.6% in ARCO stage IIIa(P<0.05). It was concluded that good and excellent mid-term follow-up could be achieved in selected patients with ONFH treated with impacted bone graft operation. The rhBMP-2 might improve the clinical efficacy and quality of bone repair. PMID:24956102

  6. Core decompression or quadratus femoris muscle pedicle bone grafting for nontraumatic osteonecrosis of the femoral head: A randomized control study

    PubMed Central

    Li, Deqiang; Li, Ming; Liu, Peilai; Zhang, Yuankai; Ma, Liang; Xu, Fei

    2016-01-01

    Background: The traditional management for osteonecrosis of the femoral head (ONFH) includes core decompression (CD) and quadratus femoris muscle pedicle bone graft (QF-MPBG). The aim of this study was to investigate the effects of CD and QF-MPBG on the patients with nontraumatic ONFH in an early stage. Materials and Methods: 39 patients (47 hips) with ONFH in an early stage (Ficat Stage I or II) were randomly divided into two groups according to random number table method. One group was treated with CD and cancellous bone grafting. Another group was treated QF-MPBG with cancellous bone grafting. The hip function was evaluated using Harris hip score (HHS). The repair of the femoral head was estimated through X-ray, computed tomography (CT), or magnetic resonance imaging (MRI). The surgical time and intraoperative blood loss was calculated. Results: All patients were followed for an average 2.5 years (range from 1.5 to 4 years). Two hips in CD group progressed into stage 3 and three hips in QF-MPBG group processed into stage 3. No patient accepted the THA at the last followup. The HHSs significantly increased in both groups after surgery (P < 0.05). No statistical differences were found between CD and QF-MPBG groups in postoperative HHSs at last followup (P > 0.05). X-ray and CT showed that the femoral head did not progress to collapse after operation in both groups. In addition, MRI showed that the edema signals decreased. However, the surgical time was longer in QF-MPBG group than that in CD group (P < 0.05). The intraoperative blood loss was more in QF-MPBG than that in CD group (P < 0.05). Conclusion: The CD with bone graft could relieve hip pain, improve hip function with much lesser surgical trauma compared to QF-MPBG. Hence, the CD with bone graft should be generally used for the treatment of patients with an early stage (Ficat Stage I or II) ONFH. PMID:27904218

  7. Osteonecrosis of the femoral head, nonunion and potential risk factors in Pauwels grade-3 femoral neck fractures

    PubMed Central

    Zhang, Yue-Lei; Chen, Song; Ai, Zi-Sheng; Gao, You-Shui; Mei, Jiong; Zhang, Chang-Qing

    2016-01-01

    Abstract The present study was to analyze clinical outcome of Pauwels grade-3 femoral neck fractures treated by different surgical techniques. Potential risk factors associated with nonunion and osteonecrosis of the femoral head (ONFH) were investigated as well. The retrospective study comprised of 67 sequential patients treated between January 2008 and December 2011. Patients with Pauwels grade-3 femoral neck fractures were treated by operative reduction and internal fixation. Cannulated screws (CS) were used in 46 patients, dynamic hip screw plus CS (DHS+CS) in 14, and locking compression plate (LCP) for proximal femur in 7. Reduction quality was assessed according to Haidukewych criteria. Postoperative radiographic examinations were conducted to observe fracture healing. Fracture displacement, comminution, fashion of internal fixation, and the sliding effect were analyzed, regarding the incidence of nonunion and ONFH. All patients had a follow-up of 21.6 ± 6.0 months on average. The phenomenon of sliding effect was observed in 16 cases (23.9%). In terms of reduction quality, 64 cases were graded as excellent, 2 were good, and 1 was poor. ONFH was presented in 15 cases (22.4%) and nonunion was found in 8 (11.9%), with 1 patient had ONFH and nonunion concomitantly. Profound hip contour was preserved in 45 cases (67.2%). The fashion of internal fixation yielded different results regarding ONFH and nonunion, whereas the effects of fracture displacement, comminution, and the sliding effect were not significant. ONFH and nonunion were common complications following Pauwels grade-3 femoral neck fractures. Higher incidence of ONFH in DHS+CS and of nonunion in the LCP group should be noted. PMID:27310950

  8. Involvement of necroptosis, a newly recognized cell death type, in steroid-induced osteonecrosis in a rabbit model

    PubMed Central

    Ichiseki, Toru; Ueda, Shusuke; Ueda, Yoshimichi; Tuchiya, Masanobu; Kaneuji, Ayumi; Kawahara, Norio

    2017-01-01

    We investigated the role of programmed necrosis (necroptosis), a newly recognized form of cell necrosis that has been implicated in the development of steroid-induced osteonecrosis. We used an osteonecrosis model in which 30 Japanese white rabbits each weighing 3.5kg were injected once with methylprednisolone at 20 mg/kg body weight into the right gluteal muscle. Ten animals killed 14 days thereafter were designated as S14d groups, while another 10 animals injected with necroptosis, a specific inhibitor of necrostatin-1 i.v. at 1.65mg/kg on the same day as the steroid were also killed on the 14th day and designated as SN14d group. As a control, 10 animals injected only with physiological saline were studied as N group. After the animals were sacrificed the bilateral femoral bone was examined histopathologically and the presence of osteonecrosis determined. Furthermore, animals subjected to the same treatment and killed on the 3rd day after drug administration were set up as S3d group and SN3d group, and Western blotting of Receptor-interacting protein ( RIP ) 1 and RIP3 in femoral bone performed. The osteonecrosis rate was 70% in S14d group, and 0% in both N and SN groups. In 2 of 10 animals in SN group fatty marrow was found. On Western blotting significantly increased expression of both RIP1 and RIP3 was noted in S3d group, confirming that Nec-1 was suppressed. Necroptosis mediated by RIP1 and RIP3 expression was thought to be implicated in the development of steroid-induced osteonecrosis. Also, by suppressing expression of RIP1 and 3 with the administration of Nec-1 the osteonecrosis rate was significantly decreased. These results suggest that necroptosis may have potential as a novel target for both elucidating the mechanisms underlying steroid-induced osteonecrosis and establishing more effective prophylactic countermeasures. PMID:28260985

  9. Radial Extracorporeal Shock Wave Therapy in a Person With Advanced Osteonecrosis of the Femoral Head

    PubMed Central

    Ma, Yue Wen; Jiang, Dong Lei; Zhang, Dai; Wang, Xiao Bei; Yu, Xiao Tong

    2016-01-01

    ABSTRACT This case report describes the first patient with avascular necrosis of the femoral head of Association Research Circulation Osseous stage IV, treated with radial extracorporeal shock wave therapy. By contrast, previous studies demonstrated the efficacy of a single treatment of focused extracorporeal shock wave therapy in improving pain and Harris Hip Scale in patients with avascular necrosis of the femoral head of Association Research Circulation Osseous stage I to III. The affected hip was treated with 6000 impulses of radial extracorporeal shock wave therapy at 10 Hz and an intensity ranging from 2.5 to 4.0 bar at 7-day intervals for 24 mos. The Harris Hip Scale values were 33, 43, 56, 77, 81, 88, and 92 at baseline and 1, 3, 6, 12, 18, and 24 mos, respectively. The radiographs showed that the subluxation of the right hip was slightly aggravated. Joint effusion was reduced, bone marrow edema disappeared, the density became more uniform, and the gluteal muscles were more developed based on magnetic resonance imaging. Increased tracer uptake was evident along the joint margin and superolateral aspect of the head both before and after radial extracorporeal shock wave therapy. This case report demonstrates the feasibility of long-term radial extracorporeal shock wave therapy in Association Research Circulation Osseous stage IV patients. PMID:27003206

  10. Radial Extracorporeal Shock Wave Therapy in a Person With Advanced Osteonecrosis of the Femoral Head.

    PubMed

    Ma, Yue Wen; Jiang, Dong Lei; Zhang, Dai; Wang, Xiao Bei; Yu, Xiao Tong

    2016-09-01

    This case report describes the first patient with avascular necrosis of the femoral head of Association Research Circulation Osseous stage IV, treated with radial extracorporeal shock wave therapy. By contrast, previous studies demonstrated the efficacy of a single treatment of focused extracorporeal shock wave therapy in improving pain and Harris Hip Scale in patients with avascular necrosis of the femoral head of Association Research Circulation Osseous stage I to III. The affected hip was treated with 6000 impulses of radial extracorporeal shock wave therapy at 10 Hz and an intensity ranging from 2.5 to 4.0 bar at 7-day intervals for 24 mos. The Harris Hip Scale values were 33, 43, 56, 77, 81, 88, and 92 at baseline and 1, 3, 6, 12, 18, and 24 mos, respectively. The radiographs showed that the subluxation of the right hip was slightly aggravated. Joint effusion was reduced, bone marrow edema disappeared, the density became more uniform, and the gluteal muscles were more developed based on magnetic resonance imaging. Increased tracer uptake was evident along the joint margin and superolateral aspect of the head both before and after radial extracorporeal shock wave therapy. This case report demonstrates the feasibility of long-term radial extracorporeal shock wave therapy in Association Research Circulation Osseous stage IV patients.

  11. Results of Total Hip Arthroplasty after Core Decompression with Tantalum Rod for Osteonecrosis of the Femoral Head

    PubMed Central

    Lee, Gun-Woo; Kim, Do-Youn; Lee, Young-Min; Eshnazarov, Kamolhuja Eshnazarovich; Yoon, Taek-Rim

    2016-01-01

    Background Early stage osteonecrosis of the femoral head (ONFH) has many treatment options including core decompression with implantation of a tantalum rod. The purpose of this study was to evaluate clinical and radiological outcomes and potential complications during conversion total hip arthroplasty (THA) in such patients. Methods Six male patients (8 hips) underwent THA subsequent to removing a tantalum rod (group I) from April 2010 to November 2011. We retrospectively reviewed the medical records of these patients. We enrolled 12 age- and sex-matched patients (16 hips) during the same period, who had undergone primary THA without a previous operation as the control group (group II). All patients were followed for at least 3 years. We checked the Harris hip score (HHS), operative time, and volume of blood loss. Radiological results, including inclination, anteversion of the acetabular cup, presence of periprosthetic osteolysis, and subsidence of femoral stem were checked at the last follow-up. Results The mean preoperative HHS values were 56.5 (range, 50 to 62) and 59.1 (range, 42 to 70) in groups I and II, respectively. The HHS improved to 96.0 (range, 93 to 100) and 97.6 (range, 93 to 100), respectively, at the 3-year follow-up (p = 0.172). Mean operation time was 98.8 minutes (range, 70 to 120 minutes) in group I and 77.5 minutes (range, 60 to 115 minutes) in group II (p = 0.006). Total blood loss volumes were 1,193.8 mL (range, 960 to 1,360 mL) and 944.1 mL (range, 640 to 1,280 mL) in groups I and II, respectively (p = 0.004). No significant differences in inclination or anteversion of acetabular cup and no evidence of osteolysis or subsidence of the femoral stem were reported in either group in radiological follow-up results. However, one case of squeaking occurred in group I during the follow-up. Conclusions The two groups showed no clinical or radiological differences except extended operative time and increased blood loss. However, the incidence of

  12. Transphyseal osseous bridges in experimental osteonecrosis of the femoral head of the rat. Histologic study of the bony bridges connecting the epiphyseal with the metaphyseal bony trabeculae through gaps in the physeal cartilage.

    PubMed

    Peskin, B; Shupak, A; Misselevich, I; Zinman, C; Levin, D; Jacob, Z; Reis, D N; Boss, J H

    2001-07-01

    In view of the lifelong persistence of the physis, the femoral head of rats may serve to model Perthes disease and slipped capital femoral epiphysis. To produce osteonecrosis, the blood supply of one femoral head of 133, 6-month-old animals was severed by circumferentially incising the periosteum of the neck and cutting the ligamentum teres. The rats were killed 7 days to 90 days postoperatively. Associated with resorption of the necrotic bone and marrow, remodeling of the epiphysis was characterized by an ingrowth of vascularized fibrous tissue, formation of new bone and some cartilage, architectural deformation and flattening of the head. In 22 of 83 rats killed 30 days or more postoperatively, gaps in the continuity of the physeal cartilage were occupied by osseous bridges, connecting newly formed epiphyseal bony trabeculae with either the preexisting or newly formed metaphyseal osseous trabeculae. This healing mode may follow ischemic death of physeal chondrocytes or be owing to another mechanism, e.g., release of mediatory substances of inflammation. These findings raise the possibility that fixation of the healing epiphysis of a child's previously necrotic femoral head to the metaphysis occurs by transphyseal osseous growth in cases in which the physis is involved in the necrotic process.

  13. Efficacy of umbilical cord-derived mesenchymal stem cell-based therapy for osteonecrosis of the femoral head: A three-year follow-up study

    PubMed Central

    Chen, Chun; Qu, Zhiguo; Yin, Xiaoguang; Shang, Chunyu; Ao, Qiang; Gu, Yongquan; Liu, Ying

    2016-01-01

    This is a retrospective analysis of the clinical effects of transplant of mesenchymal stem cells (MSCs) derived from human umbilical cord-derived MSCs (hUC-MSCs) for the treatment of osteonecrosis of the femoral head (ONFH). The biological characteristics of hUC-MSCs were assessed using flow cytometry. Nine eligible patients were enrolled in the study as they adhered to the Association Research Circulation Osseous (ARCO) classification of stage II–IIIa, and hUC-MSCs were grafted by intra-arterial infusion. Organize effective perfusion was assessed using the oxygen delivery index (ODI). The results showed that the ODI was increased at three days post-operation. The MRI results revealed that at 12 and 24 months after treatment, the necrotic volume of the femoral heads was significantly reduced. No obvious abnormalities were observed. Taken together, these data indicate that intra-arterially infused hUC-MSCs migrate into the necrotic field of femoral heads and differentiate into osteoblasts, thus improving the necrosis of femoral heads. This finding suggested that intra-arterial infusion of hUC-MSCs MSCs is a feasible and relatively safe method for the treatment of femoral head necrosis. PMID:27634376

  14. Femoral perfusion after pulsed electromagnetic field stimulation in a steroid-induced osteonecrosis model.

    PubMed

    Ikegami, Akira; Ueshima, Keiichiro; Saito, Masazumi; Ikoma, Kazuya; Fujioka, Mikihiro; Hayashi, Shigeki; Ishida, Masashi; Fujiwara, Hiroyoshi; Mazda, Osam; Kubo, Toshikazu

    2015-07-01

    This study was designed to evaluate femoral perfusion after pulsed electromagnetic field (PEMF) stimulation in a steroid-induced osteonecrosis rabbit model by dynamic contrast-enhanced magnetic resonance imaging (DCE-MRI). Steroid-induced osteonecrosis was produced by single intramuscular injection of methylprednisolone in 15 rabbits. Eight rabbits underwent PEMF stimulation (PEMF group) and seven did not (control group). DCE-MRI was performed before PEMF stimulation, immediately before steroid administration, and 1, 5, 10, and 14 days after steroid administration. Regions of interest were set in the bilateral proximal femora. Enhancement ratio (ER), initial slope (IS), and area under the curve (AUC) were analyzed. ER, IS, and AUC in the control group significantly decreased after steroid administration compared with before administration (P<0.05). In PEMF group, IS significantly decreased; however, ER and AUC showed no significant differences after steroid administration compared with before. ER and IS in PEMF group were higher than in control group until 10th day, and AUC was higher until 5th day after steroid administration (P<0.05). PEMF stimulation restrains the decrease in blood flow after steroid administration.

  15. What Is Osteonecrosis?

    MedlinePlus

    ... Osteonecrosis PDF Version Size: 59 KB Audio Version Time: 10:07 Size: 9.5 MB November 2014 What Is Osteonecrosis? Fast Facts: An Easy-to-Read Series of Publications for the Public Osteonecrosis is a ...

  16. An Exploratory Clinical Trial for Idiopathic Osteonecrosis of Femoral Head by Cultured Autologous Multipotent Mesenchymal Stromal Cells Augmented with Vascularized Bone Grafts

    PubMed Central

    Aoyama, Tomoki; Goto, Koji; Kakinoki, Ryosuke; Ikeguchi, Ryosuke; Ueda, Michiko; Kasai, Yasunari; Maekawa, Taira; Tada, Harue; Teramukai, Satoshi; Nakamura, Takashi

    2014-01-01

    Idiopathic osteonecrosis of femoral head (ION) is a painful disorder that progresses to collapse of the femoral head and destruction of the hip joint. Although its precise pathology remains unknown, the loss of blood supply causing the loss of living bone-forming cells is a hallmark of the pathophysiology of osteonecrosis. Transplantation of multipotent mesenchymal stromal cells (MSCs) is a promising tool for regenerating the musculoskeletal system. The aim of the present study was to assess the safety and efficacy of transplantation of cultured autologous bone marrow-derived MSCs mixed with β-tricalcium phosphate (β-TCP) in combination with vascularized bone grafts for the treatment of advanced stage ION in a clinical trial. Ten patients with stage 3 ION were enrolled in this study. Autologous bone marrow-derived MSCs were cultured with autologous serum, and cells (0.5–1.0×108) were transplanted after mixing with β-TCP granules in combination with vascularized iliac bone grafts. Patients were assessed 24 months after treatment. The primary and secondary endpoints were progression of the radiological stage and changes in bone volume at the femoral head, and clinical score, respectively. Nine of ten patients completed the protocol, seven of whom remained at stage 3, and the remaining two cases progressed to stage 4. The average bone volume increased from 56.5±8.5 cm3 to 57.7±10.6 cm3. The average clinical score according to the Japan Orthopaedic Association improved from 65.6±25.5 points to 87.9±19.0 points. One severe adverse event was observed, which was not related to the clinical trial. Although the efficacy of cell transplantation was still to be determined, all procedures were successfully performed and some young patients with extensive necrotic lesions with pain demonstrated good bone regeneration with amelioration of symptoms. Further improvements in our method using MSCs and the proper selection of patients will open a new approach for the

  17. Treatment with acetylsalicylic acid prevents short to mid-term radiographic progression of nontraumatic osteonecrosis of the femoral head: a pilot study

    PubMed Central

    Albers, Anthony; Carli, Alberto; Routy, Bertrand; Harvey, Edward J.; Séguin, Chantal

    2015-01-01

    Background Nontraumatic osteonecrosis of the femoral head (ONFH) is a progressive disease in young adults producing substantial morbidity and frequently resulting in total hip arthroplasty. Although hip-preserving surgical procedures represent the current mainstay of treatment for early disease, medical therapies targeting specific pathways in the ONFH pathogenesis could help prevent disease progression while producing less morbidity. Acetylsalicylic acid (ASA) is a promising alternative to other therapies for ONFH owing to its anti-inflammatory and antithrombotic mechanisms of action and its relatively benign side effect profile. Methods We followed a prospective cohort of 10 patients (12 hips) with precollapse ONFH who were given ASA to prevent disease progression. Their outcomes were compared with those of a historic control group taken from the literature. Results Progression occurred in 1 of 12 (8%) patients taking ASA compared with 30 of 45 (66.6%) controls (p = 0.002) at a mean follow-up of 3.7 years. Patients taking ASA also tended to exhibit decreased femoral head involvement at the end of therapy. Conclusion This hypothesis-generating study leads us to believe that ASA may be a simple and effective treatment option for delaying disease progression in patients with early-stage ONFH. PMID:26011853

  18. Population pharmacokinetic and pharmacodynamic modeling for assessing risk of bisphosphonate-related osteonecrosis of the jaw

    PubMed Central

    Sedghizadeh, Parish P.; Jones, Allan C.; LaVallee, Chris; Jelliffe, Roger W.; Le, Anh D.; Lee, Peter; Kiss, Andrew; Neely, Michael

    2012-01-01

    Objective We hypothesized that patients with bisphosphonate (BP)-related osteonecrosis of the jaw (BRONJ) accumulate higher levels of BP in bone than those without BRONJ. Study Design Using the Pmetrics® package and published data, we designed a population pharmacokinetic model of pamidronate concentration in plasma and bone and derived a toxic bone BP threshold of 0.2 mM. With the model, and using patient individual BP duration and bone mineral content estimated from lean body weight, we calculated bone BP levels in 153 subjects. Results Mean bone BP in 69 BRONJ cases was higher than in 84 controls (0.20 vs. 0.10 mM, P<0.001) consistent with the toxic bone threshold of 0.2 mM. BRONJ was also associated with longer duration BP therapy (5.3 vs. 2.7 years, P<0.001), older age (76 vs. 70 years, P<0.001), and Asian race (49% vs. 14%, P<0.001). Conclusions Our model accurately discriminated BRONJ cases from controls, among patients on BP therapy. PMID:23246224

  19. Prevention of osteonecrosis of the jaw by mucoperiosteal coverage in a rat model.

    PubMed

    Abtahi, J; Agholme, F; Aspenberg, P

    2013-05-01

    There is evidence for a link between the use of systemic bisphosphonates and osteonecrosis of the jaw (ONJ). This condition has the appearance of chronic osteomyelitis, and antibiotics prevent the development of ONJ in animal models. Clinically, ONJ can sometimes be treated successfully by mucoperiosteal coverage. If ONJ is indeed primarily caused by bacterial infection, immediate coverage of the extraction alveolus might reduce the risk of ONJ developing in risk patients. Therefore, we studied whether immediate mucoperiosteal coverage after tooth extraction could prevent the development of ONJ in a rat model. Thirty rats were randomly allocated to three groups (10 in each): (1) group I (controls): extraction, no drug treatment; (2) group II (non-coverage): extraction, dexamethasone plus alendronate; (3) group III (coverage): extraction, dexamethasone plus alendronate, plus coverage with a mucoperiosteal flap. Rats were examined for macroscopic ONJ-like wounds after 2 weeks. All animals in the non-coverage group developed large ONJ-like changes. The coverage and control groups showed an intact overlying mucosa in all rats. Findings were confirmed with histology. Bisphosphonates and dexamethasone caused ONJ-like lesions after tooth extraction in a rat model. This was prevented by immediate mucoperiosteal coverage. The risk of ONJ in patients using bisphosphonates might be reduced by mucoperiosteal coverage after tooth extraction.

  20. Collar Osteophytes Mimicking Osteonecrosis in Planar Bone Scintigraphy and Usefulness of SPECT/CT Images.

    PubMed

    Juang, Jr-Jian; Chen, Yi-Hsing; Tsai, Shih-Chuan; Lin, Wan-Yu

    2017-03-01

    The use of prednisolone is one major risk factor for osteonecrosis in patients with systemic lupus erythematosus. Bone scintigraphy can be a diagnostic tool for early diagnosis. We present a case who had collar osteophytes at the bilateral femoral heads, which mimicked osteonecrosis in the planar bone scintigram. An SPECT/CT scan avoided this pitfall and increased the diagnostic accuracy for osteonecrosis.

  1. Autologous bone marrow mesenchymal stem cells associated with tantalum rod implantation and vascularized iliac grafting for the treatment of end-stage osteonecrosis of the femoral head.

    PubMed

    Zhao, Dewei; Liu, Baoyi; Wang, Benjie; Yang, Lei; Xie, Hui; Huang, Shibo; Zhang, Yao; Wei, Xiaowei

    2015-01-01

    Tantalum rod implantation with vascularized iliac grafting has been reported to be an effective method for the treatment of young patients with osteonecrosis of the femoral head (ONFH) to avert the need for total hip arthroplasty (THA). However, there have been unsatisfactory success rates for end-stage ONFH. The authors describe a modified technique using bone marrow mesenchymal stem cells (BMMSCs) associated with porous tantalum rod implantation combined with vascularized iliac grafting for the treatment of end-stage ONFH. A total of 24 patients (31 hips) with end-stage ONFH were treated with surgery; ARCO IIIc stage was observed in 19 hips and ARCO IV stage was observed in 12 hips. All patients were followed for a mean time of 64.35 ± 13.03 months (range 26-78). Operations on only five hips were converted to THA. The joint-preserving success rate of the entire group was 89.47% for ARCO stage IIIc and 75% for ARCO stage IV. The mean Harris hip score of the 31 hips improved significantly from 38.74 ± 5.88 points (range 22-50) to 77.23 ± 14.75 points (range 33-95). This intervention was safe and effective in delaying or avoiding total hip replacement for end-stage ONFH.

  2. Treatment of steroid-induced osteonecrosis of the femoral head using porous Se@SiO2 nanocomposites to suppress reactive oxygen species.

    PubMed

    Deng, Guoying; Niu, Kerun; Zhou, Feng; Li, Buxiao; Kang, Yingjie; Liu, Xijian; Hu, Junqing; Li, Bo; Wang, Qiugen; Yi, Chengqing; Wang, Qian

    2017-03-03

    Reducing oxidative stress (ROS) have been demonstrated effective for steroid-induced osteonecrosis of the femoral head (steroid-induced ONFH). Selenium (Se) plays an important role in suppressing oxidative stress and has huge potential in ONFH treatments. However the Se has a narrow margin between beneficial and toxic effects which make it hard for therapy use in vivo. In order to make the deficiency up, a control release of Se (Se@SiO2) were realized by nanotechnology modification. Porous Se@SiO2 nanocomposites have favorable biocompatibility and can reduced the ROS damage effectively. In vitro, the cck-8 analysis, terminal dexynucleotidyl transferase (TdT)-mediated dUTP nick end labeling (TUNEL) stain and flow cytometry analysis showed rare negative influence by porous Se@SiO2 nanocomposites but significantly protective effect against H2O2 by reducing ROS level (detected by DCFH-DA). In vivo, the biosafety of porous Se@SiO2 nanocomposites were confirmed by the serum biochemistry, the ROS level in serum were significantly reduced and the curative effect were confirmed by Micro CT scan, serum Elisa assay (inflammatory factors), Western blotting (quantitative measurement of ONFH) and HE staining. It is expected that the porous Se@SiO2 nanocomposites may prevent steroid-induced ONFH by reducing oxidative stress.

  3. A 10-Year Follow-Up of Two-Incision and Modified Watson-Jones Total Hip Arthroplasty in Patients with Osteonecrosis of the Femoral Head

    PubMed Central

    Lin, Shih-Jie; Lin, Po-Chun; Kuo, Feng-Chih; Peng, Kuo-Ti; Huang, Kuo-Chin

    2017-01-01

    Long-term data and information indicating whether minimally invasive surgery (MIS) approaches are safe and effective with total hip arthroplasty (THA) are lacking. Between 2004 and 2006, 75 patients with alcohol-related osteonecrosis of the femoral head (ONFH) who underwent 75 THAs with the two-incision approach were studied. The medical records, radiographic parameters, and functional outcomes were collected prospectively. All data were compared with those for matched patients who underwent a modified Watson-Jones (WJ) approach. THA using the two-incision approach was associated with longer operation time, more blood loss, more lateral femoral cutaneous nerve injury, and more periprosthetic femoral fractures (p < 0.05 for all four) than the modified WJ approach. The Harris Hip Score (HHS) and Western Ontario and McMaster University Osteoarthritis Index (WOMAC) increased significantly from the period preoperatively to 6 weeks postoperatively and thereafter up to the last follow-up in both groups. However, there were no significant differences in terms of radiographic parameters and functional outcomes between the two groups throughout the study period. Both the two-incision and the modified WJ approach provided satisfactory results and survival rates at a mean follow-up of 10.8 years. A prospective, randomized, large-scale cohort study is still warranted for evidence-based recommendations. PMID:28386565

  4. Autologous Bone Marrow Mesenchymal Stem Cells Associated with Tantalum Rod Implantation and Vascularized Iliac Grafting for the Treatment of End-Stage Osteonecrosis of the Femoral Head

    PubMed Central

    Zhao, Dewei; Liu, Baoyi; Wang, Benjie; Yang, Lei; Xie, Hui; Huang, Shibo; Zhang, Yao; Wei, Xiaowei

    2015-01-01

    Tantalum rod implantation with vascularized iliac grafting has been reported to be an effective method for the treatment of young patients with osteonecrosis of the femoral head (ONFH) to avert the need for total hip arthroplasty (THA). However, there have been unsatisfactory success rates for end-stage ONFH. The authors describe a modified technique using bone marrow mesenchymal stem cells (BMMSCs) associated with porous tantalum rod implantation combined with vascularized iliac grafting for the treatment of end-stage ONFH. A total of 24 patients (31 hips) with end-stage ONFH were treated with surgery; ARCO IIIc stage was observed in 19 hips and ARCO IV stage was observed in 12 hips. All patients were followed for a mean time of 64.35 ± 13.03 months (range 26–78). Operations on only five hips were converted to THA. The joint-preserving success rate of the entire group was 89.47% for ARCO stage IIIc and 75% for ARCO stage IV. The mean Harris hip score of the 31 hips improved significantly from 38.74 ± 5.88 points (range 22–50) to 77.23 ± 14.75 points (range 33–95). This intervention was safe and effective in delaying or avoiding total hip replacement for end-stage ONFH. PMID:25802840

  5. Treatment of steroid-induced osteonecrosis of the femoral head using porous Se@SiO2 nanocomposites to suppress reactive oxygen species

    NASA Astrophysics Data System (ADS)

    Deng, Guoying; Niu, Kerun; Zhou, Feng; Li, Buxiao; Kang, Yingjie; Liu, Xijian; Hu, Junqing; Li, Bo; Wang, Qiugen; Yi, Chengqing; Wang, Qian

    2017-03-01

    Reducing oxidative stress (ROS) have been demonstrated effective for steroid-induced osteonecrosis of the femoral head (steroid-induced ONFH). Selenium (Se) plays an important role in suppressing oxidative stress and has huge potential in ONFH treatments. However the Se has a narrow margin between beneficial and toxic effects which make it hard for therapy use in vivo. In order to make the deficiency up, a control release of Se (Se@SiO2) were realized by nanotechnology modification. Porous Se@SiO2 nanocomposites have favorable biocompatibility and can reduced the ROS damage effectively. In vitro, the cck-8 analysis, terminal dexynucleotidyl transferase (TdT)-mediated dUTP nick end labeling (TUNEL) stain and flow cytometry analysis showed rare negative influence by porous Se@SiO2 nanocomposites but significantly protective effect against H2O2 by reducing ROS level (detected by DCFH-DA). In vivo, the biosafety of porous Se@SiO2 nanocomposites were confirmed by the serum biochemistry, the ROS level in serum were significantly reduced and the curative effect were confirmed by Micro CT scan, serum Elisa assay (inflammatory factors), Western blotting (quantitative measurement of ONFH) and HE staining. It is expected that the porous Se@SiO2 nanocomposites may prevent steroid-induced ONFH by reducing oxidative stress.

  6. Study on correlation between bone marrow edema, stage of necrosis and area ratio of necrosis with the hip pain grading in nontraumatic osteonecrosis of the femoral head

    PubMed Central

    Jianchuan, Wang; Lei, Yang; Benjie, Wang; Dewei, Zhao

    2015-01-01

    The objective of this study was to explore the correlation between bone marrow edema, stage of necrosis, and area ratio of necrosis with the hip pain grading in non-traumatic osteonecrosis of the femoral head. Bone marrow edema grading at all levels and the hip pain grade differences were statistically significant (P < 0.001). Bone marrow edema grading increased by levels of 0, 1, and 2, whereas average pain rating increased as well to 40.73, 104.66 and 143.49. I ~ III period stage of necrosis and the hip pain grade difference was statistically significant (P < 0.001), with the average grade progress pain stage by the death of a rank gradually increased, I period, II period, III period was 57.00, 88.58 and 120.62, respectively. Area ratio of necrosis between 0 ~ 3 were positively correlated with pain, compared the two was statistically significant (P < 0.001), and with the degree of pathological changes is aggravating, increase the average rank of levels of pain. 0, 1, 2 and 3 are 36.88, 98.03, 123.87 and 151.93 respectively. We can choose the treatment method and evaluate treatment effect by considering a patients’ degree of bone marrow edema, stage of necrosis and area ratio of necrosis.

  7. Treatment of steroid-induced osteonecrosis of the femoral head using porous Se@SiO2 nanocomposites to suppress reactive oxygen species

    PubMed Central

    Deng, Guoying; Niu, Kerun; Zhou, Feng; Li, Buxiao; Kang, Yingjie; Liu, Xijian; Hu, Junqing; Li, Bo; Wang, Qiugen; Yi, Chengqing; Wang, Qian

    2017-01-01

    Reducing oxidative stress (ROS) have been demonstrated effective for steroid-induced osteonecrosis of the femoral head (steroid-induced ONFH). Selenium (Se) plays an important role in suppressing oxidative stress and has huge potential in ONFH treatments. However the Se has a narrow margin between beneficial and toxic effects which make it hard for therapy use in vivo. In order to make the deficiency up, a control release of Se (Se@SiO2) were realized by nanotechnology modification. Porous Se@SiO2 nanocomposites have favorable biocompatibility and can reduced the ROS damage effectively. In vitro, the cck-8 analysis, terminal dexynucleotidyl transferase (TdT)-mediated dUTP nick end labeling (TUNEL) stain and flow cytometry analysis showed rare negative influence by porous Se@SiO2 nanocomposites but significantly protective effect against H2O2 by reducing ROS level (detected by DCFH-DA). In vivo, the biosafety of porous Se@SiO2 nanocomposites were confirmed by the serum biochemistry, the ROS level in serum were significantly reduced and the curative effect were confirmed by Micro CT scan, serum Elisa assay (inflammatory factors), Western blotting (quantitative measurement of ONFH) and HE staining. It is expected that the porous Se@SiO2 nanocomposites may prevent steroid-induced ONFH by reducing oxidative stress. PMID:28256626

  8. [Potential uses of cytokines and growth factors in treatment of osteonecrosis].

    PubMed

    Hungerford, M W; Mont, M A

    2000-05-01

    Osteonecrosis of the femoral head remains a devastating disease for young patients. As the normal process of bone formation, bone destruction, and fracture healing becomes more clearly understood, molecular agents--including cytokines, bone morphogenetic proteins, and angiogenic factors--will be identified as potential therapeutic agents for the treatment of osteonecrosis. As the pathology of osteonecrosis and repair of osteonecrotic lesions becomes clear, the potential combination of these molecular factors to influence the outcome of the disease in its repair process should become evident. With the myriad of agents and combinations of agents which may be beneficial in the treatment of osteonecrosis, a reproducible animal model is urgently needed to determine which of these combinations is most effective. Despite the lack of an animal model, progress in the use of cytokines for osteonecrosis treatment in conjunction with traditional treatment methods is possible in human subjects. This is due to the extremely low incidence of adverse reactions when these cytokines are used locally in nanogram to microgram quantities.

  9. The effects of enoxaparin on the reparative processes in experimental osteonecrosis of the femoral head of the rat.

    PubMed

    Norman, Doron; Miller, Yoav; Sabo, Edmund; Misselevich, Ines; Peskin, Bezalel; Zinman, Chaim; Levin, Daniel; Reis, Daniel N; Boss, Jochanan H

    2002-03-01

    The blood supply of one femoral head of 6-month-old rats was severed by incising the periosteum of the neck and cutting the ligamentum teres. The rats were killed on the 30th postoperative day and the femoral bones were obtained for semiquantification of the reparative processes in the necrotic heads. Fourteen rats were treated with enoxaparin and 14 untreated animals served as controls. Statistically, the amounts of necrotic bone in the epiphysis were less, the extent of remodeling of the femoral heads was milder, and the articular cartilage degeneration was slighter in the enoxaparin-treated than untreated rats. There was no significant difference in the quantities of newly formed bone in femoral heads of treated and untreated rats. These findings are in agreement with the known effects of unfractionated and low-molecular-weight heparins which enhance osteoclastic bone resorption and angiogenesis and decrease osteoblastic bone formation. The former activities, operative in minimizing the structural distortion of the femoral head, oppose the crucial event in the pathogenesis of post-osteonecrotic osteoarthritis.

  10. Functional investigation of bone implant viability using radiotracers in a new model of osteonecrosis

    PubMed Central

    Schiper, Luis; Faintuch, Bluma Linkowski; da Silva Badaró, Roberto José; de Oliveira, Erica Aparecida; Chavez, Victor E. Arana; Chinen, Elisangela; Faintuch, Joel

    2016-01-01

    OBJECTIVES: Conventional imaging methods are excellent for the morphological characterization of the consequences of osteonecrosis; however, only specialized techniques have been considered useful for obtaining functional information. To explore the affinity of radiotracers for severely devascularized bone, a new mouse model of isolated femur implanted in a subcutaneous abdominal pocket was devised. To maintain animal mobility and longevity, the femur was harvested from syngeneic donors. Two technetium-99m-labeled tracers targeting angiogenesis and bone matrix were selected. METHODS: Medronic acid and a homodimer peptide conjugated with RGDfK were radiolabeled with technetium-99m, and biodistribution was evaluated in Swiss mice. The grafted and control femurs were evaluated after 15, 30 and 60 days, including computed tomography (CT) and histological analysis. RESULTS: Radiolabeling achieved high (>95%) radiochemical purity. The biodistribution confirmed good blood clearance 1 hour after administration. For 99mTc-hydrazinonicotinic acid (HYNIC)-E-[c(RGDfK)2, remarkable renal excretion was observed compared to 99mTc-methylene diphosphonate (MDP), but the latter, as expected, revealed higher bone uptake. The results obtained in the control femur were equal at all time points. In the implanted femur, 99mTc-HYNIC-E-[c(RGDfK)2 uptake was highest after 15 days, consistent with early angiogenesis. Regarding 99mTc-MDP in the implant, similar uptake was documented at all time points, consistent with sustained bone viability; however, the uptake was lower than that detected in the control femur, as confirmed by histology. CONCLUSIONS: 1) Graft viability was successfully diagnosed using radiotracers in severely ischemic bone at all time points. 2) Analogously, indirect information about angiogenesis could be gathered using 999mTc-HYNIC-E-[c(RGDfK)2. 3) These techniques appear promising and warrant further studies to determine their potential clinical applications. PMID

  11. Significant Associations of SOX9 Gene Polymorphism and Gene Expression with the Risk of Osteonecrosis of the Femoral Head in a Han Population in Northern China

    PubMed Central

    Song, Yang; Ren, Ming; Yang, Qiwei; Sui, Yujie; Wang, Qingyu; Wang, Ao; Zhao, Haiyue

    2016-01-01

    Sex determining region Y-box 9 (SOX9) is a key transcription factor involved in cartilage formation during the embryonic development stage and cartilage growth and repair after birth. To explore the roles of polymorphism and expression of the SOX9 gene in the development of osteonecrosis of the femoral head (ONFH), we analyzed the polymorphism of rs12601701 [A/G] and rs1042667 [A/C] and the serum protein expression of the SOX9 gene in 182 patients with ONFH and 179 healthy control subjects. Results revealed that the A-A haplotype of SOX9 gene as well as the GG and AA genotypes of rs12601701 was significantly associated with increased ONFH risk (P = 0.038) and the risk of bilateral hip lesions of ONFH (P = 0.009), respectively. The C-A, A-A, and A-G haplotypes were also statistically associated with the decreased and increased risk of bilateral hip lesions of ONFH (P = 0.03, P = 0.048, and P = 0.013), respectively, while the A-A haplotype closely related to the clinical stages of ONFH (P = 0.041). More importantly, the serum SOX9 protein expression of the ONFH group was greatly decreased compared to control group (P = 0.0001). Our results first showed that the gene polymorphism and gene expression of SOX9 were significantly associated with the risk and clinical phenotypes of ONFH and also indicate that the SOX9 gene may play a key role in the development of ONFH. PMID:28090537

  12. Long non-coding RNA HOTAIR inhibits miR-17-5p to regulate osteogenic differentiation and proliferation in non-traumatic osteonecrosis of femoral head

    PubMed Central

    Zhao, Baoxiang; Guo, Xiaxia; Liu, Song

    2017-01-01

    Background and aim The biological functions of non-coding RNAs (ncRNAs) have been widely identified in many human diseases. In the present study, the relationship between long non-coding RNA HOTAIR and microRNA-17-5p (miR-17-5p) and their roles in osteogenic differentiation and proliferation in non-traumatic osteonecrosis of femoral head (ONFH) were investigated. Methods The expression levels of HOTAIR and miR-17-5p in the mesenchymal stem cells (MSCs) derived from patients with non-traumatic ONFH and osteoarthritis (OA) were examined by real-time PCR. BMP-2 induced human MSCs from bone marrow (hMSC-BM) were used for osteogenic differentiation. Results It was observed that the expression level of miR-17-5p was lower and the level of HOTAIR was higher in samples of non-traumatic ONFH compared with OA. HOTAIR downregulation induced by si-HOTAIR led to the increase of miR-17-5p expression and the decrease of miR-17-5p target gene SMAD7 expression. The values of osteogenic differentiation markers, including RUNX2 and COL1A1 mRNA expression and ALP activity, were also elevated by si-HOTAIR. However, the increase of these values was canceled by miR-17-5p inhibitor or SMAD7 upregulation. Conclusion HOTAIR played a role in regulating osteogenic differentiation and proliferation through modulating miR-17-5p and its target gene SMAD7 in non-traumatic ONFH. PMID:28207735

  13. Exosomes derived from human platelet-rich plasma prevent apoptosis induced by glucocorticoid-associated endoplasmic reticulum stress in rat osteonecrosis of the femoral head via the Akt/Bad/Bcl-2 signal pathway

    PubMed Central

    Tao, Shi-Cong; Yuan, Ting; Rui, Bi-Yu; Zhu, Zhen-Zhong; Guo, Shang-Chun; Zhang, Chang-Qing

    2017-01-01

    An excess of glucocorticoids (GCs) is reported to be one of the most common causes of osteonecrosis of the femoral head (ONFH). In addition, GCs can induce bone cell apoptosis through modulating endoplasmic reticulum (ER) stress. Among the three main signal pathways in ER stress, the PERK (protein kinase RNA-like ER kinase)/CHOP (CCAAT-enhancer-binding protein homologous protein) pathway has been considered to be closely associated with apoptosis. Platelet-rich plasma (PRP) has been referred to as a concentration of growth factors and the exosomes derived from PRP (PRP-Exos) have a similar effect to their parent material. The enriched growth factors can be encapsulated into PRP-Exos and activate Akt and Erk pathways to promote angiogenesis. Activation of the Akt pathway may promote the expression of anti-apoptotic proteins like Bcl-2, while CHOP can inhibit B-cell lymphoma 2 (Bcl-2) expression to increase the level of cleaved caspase-3 and lead to cell death. Consequently, we hypothesized that PRP-Exos prevent apoptosis induced by glucocorticoid-associated ER stress in rat ONFH via the Akt/Bad/Bcl-2 signal pathway. To verify this hypothesis, a dexamethasone (DEX)-treated in vitro cell model and methylprednisolone (MPS)-treated in vivo rat model were adopted. Characterization of PRP-Exos, and effects of PRP-Exos on proliferation, apoptosis, angiogenesis, and osteogenesis of cells treated with GCs in vitro and in vivo were examined. Furthermore, the mechanism by which PRP-Exos rescue the GC-induced apoptosis through the Akt/Bad/Bcl-2 pathway was also investigated. The results indicate that PRP-Exos have the capability to prevent GC-induced apoptosis in a rat model of ONFH by promoting Bcl-2 expression via the Akt/Bad/Bcl-2 signal pathway under ER stress. PMID:28255363

  14. Tibial osteonecrosis.

    PubMed

    Lonner, J H; Lotke, P A

    2001-01-01

    Spontaneous osteonecrosis of the tibial plateau involves a continuum of change observed in the subchondral zone that is commonly associated with early and mid stages of osteoarthritis. The typical patient is an elderly woman who experiences a sudden onset of pain in the medial aspect of the knee. The diagnosis of this under-appreciated clinical entity may be difficult, but careful examination and judicious use of imaging studies, as well as a high index of suspicion, may facilitate the accurate diagnosis. Although the radiographs may initially be normal (with the exception of mild arthrosis), radionuclide scans and MRI can be of great value. The MRI studies usually show a decreased signal intensity on a T1-weighted image, but may be normal in the early course of the disease. The T2-weighted images and fat suppression views are helpful in establishing a diagnosis and determining the extent of involvement. Recognition of this problem may help to avoid unnecessary intra-articular surgery. Many of these patients have complete or partial resolution of symptoms by 1 year, after a period of protected weight bearing. Nonetheless, surgery may be necessary for more advanced lesions and in those patients with progressive arthrosis.

  15. High-Energy Extracorporeal Shock Wave for Early Stage Osteonecrosis of the Femoral Head: A Single-Center Case Series

    PubMed Central

    Gao, Fuqiang; Sun, Wei; Li, Zirong; Guo, Wanshou; Wang, Weiguo; Cheng, Liming; Wang, Bailiang

    2015-01-01

    Our retrospective study assessed the effects of treatment of early stage ONFH with extracorporeal shock wave therapy. 335 patients (528 hips) were treated with shockwave therapy in our institution. Each patient underwent two sessions. The hips were divided into two groups according to whether the lateral pillar of the femoral head (LPFH) was preserved: LPFH and non-LPFH groups. Patients were followed up at 3, 6, and 12 months after the treatment. Most of the patients (83.9% hips) demonstrated pain reduction and improved mobility of the treated joint (visual analogue scale score, P = 0.00006; Harris hip score, P = 0.00091). During the follow-up period, 16 hips failed following femoral head collapse and required hip arthroplasty (2 hips in LPFH group and 14 hips in non-LPFH group). The lesion size decreased after ESWT. However, the differences were statistically not significant (LPFH group, P = 0.091; non-LPFH group, P = 0.087). A significant reduction in bone marrow edema was observed after treatment (LPFH group, P = 0.007; non-LPFH group, P = 0.016). High-energy extracorporeal shock wave therapy resulted in considerable improvement in early stage ONFH, which can effectively relieve pain and improve the function of the hip. PMID:26609311

  16. Model of beam head erosion

    SciTech Connect

    Lee, E.P.

    1980-08-08

    An analytical model of beam head dynamics is presented, leading to an estimate of the erosion rate due to the combined effects of Ohmic dissipation and scattering. Agreement with the results of a computer simulation and detailed one-dimensional computations is good in all respects except for the scaling of the erosion rate with net current.

  17. Relation between the development of osteoporosis and osteonecrosis following glucocorticoid in a rabbit model

    PubMed Central

    Lin, Tao; Liu, Junbin; Yang, Shuhua; Liu, Xianzhe; Feng, Xiaobo; Fu, Dehao

    2016-01-01

    Background: There has been a recent increase in the number of patients suffering from bone and joint diseases, as a consequence of corticosteroids administration. There are more patients treated with low dose of GCs under long-term conditions in clinical, such as effect of GCs on Rheumatoid arthritis, Crohn's disease and Asthma patients. Hence, it was difficult for doctor to determine which problem occur first – OP or ON; however, there was no clinical report previously in the literature, and there was no effective animal model of OP and ON about low dose GCs. This study was conducted to develop rabbit models of glucocorticoid (GC)-induced femoral head ON and OP and to investigate the temporal relationship between the occurrence of the two events following administration of glucocorticoids. Materials and Methods: Fifty six, 6 months old female rabbits were randomly divided into the GC group and control group (C). Rabbits received gluteal injections of methylprednisolone sodium succinate once a day for 4 weeks, while normal saline solution in the control group. Rabbits were sacrificed at 0, 2, 4, and 8 weeks. Hip magnetic resonance imaging was performed before the rabbits were sacrificed. Serum calcium (Ca), phosphorus (P), total cholesterol, and triglyceride levels were also measured. The bone mineral density (BMD) of femoral head and the femoral shaft were measured by dual-energy X-ray absorptiometry. The trabecular parameters of the femur and the 4th lumbar vertebrae (L4) were measured with a micro-computed tomography (μ-CT). Also, the femoral head was stained with hematoxylin-eosin staining. Results: At 4 weeks in the GC group, the BMD of the femur reduced 33% and 22% in the femoral head and shaft; there was irregular intermediate to high T2-weighted images signals; μ-CT showed microfractures and cystic changes in the femoral head and L4 at 4 weeks. At 8 weeks in the GC group, the classical “line-like sign” indicating ON of the femoral head was observed

  18. Aggravated bone density decline following symptomatic osteonecrosis in children with acute lymphoblastic leukemia.

    PubMed

    den Hoed, Marissa A H; Pluijm, Saskia M F; te Winkel, Mariël L; de Groot-Kruseman, Hester A; Fiocco, Martha; Hoogerbrugge, Peter; Leeuw, Jan A; Bruin, Marrie C A; van der Sluis, Inge M; Bresters, Dorien; Lequin, Maarten H; Roos, Jan C; Veerman, Anjo J P; Pieters, Rob; van den Heuvel-Eibrink, Marry M

    2015-12-01

    Osteonecrosis and decline of bone density are serious side effects during and after treatment of childhood acute lymphoblastic leukemia. It is unknown whether osteonecrosis and low bone density occur together in the same patients, or whether these two osteogenic side-effects can mutually influence each other's development. Bone density and the incidence of symptomatic osteonecrosis were prospectively assessed in a national cohort of 466 patients with acute lymphoblastic leukemia (4-18 years of age) who were treated according to the dexamethasone-based Dutch Child Oncology Group-ALL9 protocol. Bone mineral density of the lumbar spine (BMDLS) (n=466) and of the total body (BMDTB) (n=106) was measured by dual X-ray absorptiometry. Bone density was expressed as age- and gender-matched standard deviation scores. Thirty patients (6.4%) suffered from symptomatic osteonecrosis. At baseline, BMDLS and BMDTB did not differ between patients who did or did not develop osteonecrosis. At cessation of treatment, patients with osteonecrosis had lower mean BMDLS and BMDTB than patients without osteonecrosis (respectively, with osteonecrosis: -2.16 versus without osteonecrosis: -1.21, P<0.01 and with osteonecrosis: -1.73 versus without osteonecrosis: -0.57, P<0.01). Multivariate linear models showed that patients with osteonecrosis had steeper BMDLS and BMDTB declines during follow-up than patients without osteonecrosis (interaction group time, P<0.01 and P<0.01). We conclude that bone density status at the diagnosis of acute lymphoblastic leukemia does not seem to influence the occurrence of symptomatic osteonecrosis. Bone density declines from the time that osteonecrosis is diagnosed; this suggests that the already existing decrease in bone density during acute lymphoblastic leukemia therapy is further aggravated by factors such as restriction of weight-bearing activities and destruction of bone architecture due to osteonecrosis. Osteonecrosis can, therefore, be considered a risk

  19. Investigating Clinical Failure of Bone Grafting through a Window at the Femoral Head Neck Junction Surgery for the Treatment of Osteonecrosis of the Femoral Head

    PubMed Central

    Sun, Wei; Zhao, Dingyan; Gao, Fuqiang; Su, Yangming; Li, Zirong

    2016-01-01

    Aims This study aimed to analyze the clinical factors related to the failure of bone grafting through a window at the femoral head-neck junction. Methods In total, 119 patients (158 hips) underwent bone grafting for treatment of avascular necrosis of the femoral head. The patients were classified by their ARCO staging and CJFH classification. All patients were clinically and radiographically followed up every three months during the first year and every six months in the following year. The clinical follow-up comprised determination of pre- and postoperative Harris hip scores, while serial AP, frog lateral radiographs, and CT scan were used for the radiographic follow-up. Results The clinical failure of bone grafting was observed in 40 patients. The clinical failure rates in patients belonging to ARCO stage II period, IIIa, and III (b + c) were 25.9%, 16.2%, and 61.5%, respectively, while those in patients belonging to (C + M + L1) type and L2, L3 type disease groups were 1.7%, 38.9%, and 39%, respectively. The clinical failure rates in patients aged below 40 and those aged 40 and over were 20.5% and 39.0%, respectively (all P < 0.05). Conclusion Disease type, disease stage, and patient age are risk factors for failure of bone graft surgery. Patients belonging to ARCO stage II and IIIa showed a good overall response rate, while patients belonging to ARCO stage IIIb and IIIc and those with necrotic lesions involving the lateral pillar (L2 and L3 type) showed high surgical failure rates. PMID:27285821

  20. ACTH protects against glucocorticoid-induced osteonecrosis of bone.

    PubMed

    Zaidi, Mone; Sun, Li; Robinson, Lisa J; Tourkova, Irina L; Liu, Li; Wang, Yujuan; Zhu, Ling-Ling; Liu, Xuan; Li, Jianhua; Peng, Yuanzhen; Yang, Guozhe; Shi, Xingming; Levine, Alice; Iqbal, Jameel; Yaroslavskiy, Beatrice B; Isales, Carlos; Blair, Harry C

    2010-05-11

    We report that adrenocorticotropic hormone (ACTH) protects against osteonecrosis of the femoral head induced by depot methylprednisolone acetate (depomedrol). This therapeutic response likely arises from enhanced osteoblastic support and the stimulation of VEGF by ACTH; the latter is largely responsible for maintaining the fine vascular network that surrounds highly remodeling bone. We suggest examining the efficacy of ACTH in preventing human osteonecrosis, a devastating complication of glucocorticoid therapy.

  1. National Osteonecrosis Foundation

    MedlinePlus

    ... Foundation is made up of a group of patients, physicians and others who want to see the end ... NONF Brochure | Legg Perthes Disease Borchure | Membership Form | Patient Questionnaire | Physician Members Copyright © 2014, National Osteonecrosis Foundaton. All Rights ...

  2. Osteonecrosis of the jaw.

    PubMed

    Sambrook, Philip N; Ebeling, Peter

    2008-04-01

    Bisphosphonates are effective therapy for osteoporosis, Paget's disease, and metastatic bone disease. Generally, the side effects of bisphosphonates are minimal. Recently, an uncommon adverse reaction affecting the maxilla or mandible, called osteonecrosis of the jaw, has been reported, especially in those patients receiving high doses of bisphosphonates in the oncology setting. Regarding doses used to treat osteoporosis, clinicians must keep the very small potential absolute risk of jaw osteonecrosis in perspective and consider it in relation to the demonstrated benefit of bisphosphonates. Still, in a very small number of patients taking bisphosphonates, intractable, painful, nonhealing exposed bone may occur following dental extractions or denture irritation.

  3. Combination treatment of biomechanical support and targeted intra-arterial infusion of peripheral blood stem cells mobilized by granulocyte-colony stimulating factor for the osteonecrosis of the femoral head: a randomized controlled clinical trial.

    PubMed

    Mao, Qiang; Wang, Weidong; Xu, Taotao; Zhang, Shanxing; Xiao, Luwei; Chen, Di; Jin, Hongting; Tong, Peijian

    2015-04-01

    The objective of this study was to determine the benefits of combination treatment with mechanical support and targeted intra-arterial infusion of peripheral blood stem cells (PBSCs) mobilized by granulocyte-colony stimulating factor (G-CSF) via the medial circumflex femoral artery on the progression of osteonecrosis of the femoral head (ONFH). Fifty-five patients (89 hips) with early and intermediate stage ONFH were recruited and randomly assigned to combination treatment or mechanical support treatment (control group). All hips received mechanical support treatment (porous tantalum rod implantation). Then, hips in the combination treatment group were performed targeted intra-arterial infusion of PBSCs. At each follow-up, Harris hip score (HHS) and Association Research Circulation Osseous (ARCO) classification were used to evaluate the symptoms and progression of osteonecrosis. Total hip arthroplasty (THA) was assessed as an endpoint at each follow-up. At 36 months, 9 of the 41 hips (21.95%) in the control group progressed to clinical failure and underwent THA whereas only 3 of the 48 hips (6.25%) in the combination treatment group required THA (p = 0.031). Kaplan-Meier survival analysis showed a significant difference in the survival time between the two groups (log-rank test; p = 0.025). Compared to the control group, combination treatment significantly improved the HHS at 36 months (p = 0.003). At the final follow-up examination, radiological progression was noted in 13 of 41 hips (31.71%) for the control group, but in only 4 of 48 hips (8.33%) for the combination treatment group (p = 0.005). The overall collapse rates were 15.15% (5/33 hips) and 8.11% (3/37 hips) in the control and combination treatment groups, respectively. Targeted intra-arterial infusion of PBSCs is capable of enhancing the efficacy of biomechanical support in the treatment of ONFH. This clinical trial confirmed that the combination treatment might be a safe and feasible

  4. Hydrogen-rich saline attenuates steroid-associated femoral head necrosis through inhibition of oxidative stress in a rabbit model

    PubMed Central

    HUANG, SHENG-LI; JIAO, JIAN; YAN, HONG-WEI

    2016-01-01

    A growing body of evidence suggests that hydrogen is a novel, selective antioxidant that exerts a protective effect against organ damage. The present study investigated the effect of hydrogen-rich saline on corticosteroid-induced necrosis of the femoral head in an animal model established using prednisolone. A total of 30 healthy, male, adult New Zealand white rabbits were randomly divided into two groups: Hydrogen-rich saline (treated with hydrogen-rich saline via intraperitoneal injection) and placebo (treated with normal saline). At the set time-points, the structure of the femoral head was examined using a microscope; the concentrations of glutathione (GSH), lipid peroxide (LPO), vascular endothelial growth factor (VEGF) and thrombomodulin (TM) in the plasma were measured and the microvessel density was quantified. The results showed that hydrogen-rich saline significantly decreased the levels of VEGF, TM and LPO and increased the GSH level in steroid-associated necrosis of the femoral head in the rabbit model. A significant increase in the microvessel density was observed in the hydrogen-rich saline group. Histopathological staining confirmed the results of the biochemical analysis. The present study demonstrates that hydrogen treatment may alleviate steroid-associated osteonecrosis by inhibiting oxidative stress. Hydrogen-rich saline may provide an alternative treatment for steroid-associated necrosis of the femoral head. PMID:26889236

  5. Factors associated with osteonecrosis of the jaw among bisphosponate users

    PubMed Central

    Hess, Lisa M; Jeter, Joanne M; Benham-Hutchins, Marge; Alberts, David S.

    2008-01-01

    Background Bisphosphonates are medications that impact bone reformation by inhibiting osteoclast function. Osteonecrosis of the jaw has been reported among patients receiving these medications. It is unclear if the risk factors associated with osteonecrosis of the jaw among cancer patients taking bisphosphonates are also possible risk factors among patients receiving these medications for other indications. Methods A systematic review search strategy was used to identify cases of osteonecrosis of the jaw among patients taking bisphosphonates for an indication other than cancer to identify potential contributing factors. Data were analyzed according to previous models to develop a more expanded model that may explain possible mechanisms for the development of osteonecrosis of the jaw among patients without cancer. Results Ninety-nine cases of osteonecrosis of the jaw were identified among patients who were prescribed a bisphosphonate for an indication other than cancer. These cases included 85 osteoporosis patients, 10 patients with Paget’s disease, two patients with rheumatoid arthritis, one patient with diabetes and one patient with maxillary fibrous dysplasia. The mean age was 69.4 years, 87.3% were female, and 87.6% were receiving oral, but not intravenous, bisphosphonates. Of the 63 patients reporting dental care information, 88.9% had a dental procedure prior to the onset of osteonecrosis of the jaw. Of all cases providing medical information, 71% were taking at least one medication that affects bone turnover in addition to the bisphosphonate, and 81.6% reported additional underlying health conditions. Conclusions The case details suggest a multiplicity of factors associated with this condition and provide the foundation for a model outlining the potential mechanism for the development of osteonecrosis of the jaw among patients taking bisphosphonates for an indication other than cancer. PMID:18501224

  6. A stochastic model for head lice infections.

    PubMed

    Stone, Patricia; Wilkinson-Herbots, Hilde; Isham, Valerie

    2008-06-01

    We investigate the dynamics of head lice infections in schools, by considering a model for endemic infection based on a stochastic SIS (susceptible-infected-susceptible) epidemic model, with the addition of an external source of infection. We deduce a range of properties of our model, including the length of a single outbreak of infection. We use the stationary distribution of the number of infected individuals, in conjunction with data from a recent study carried out in Welsh schools on the prevalence of head lice infections, and employ maximum likelihood methods to obtain estimates of the model parameters. A complication is that, for each school, only a sample of the pupils was checked for infection. Our likelihood function takes account of the missing data by incorporating a hypergeometric sampling element. We arrive at estimates of the ratios of the "within school" and "external source" transmission rates to the recovery rate and use these to obtain estimates for various quantities of interest.

  7. From the radiologic pathology archives imaging of osteonecrosis: radiologic-pathologic correlation.

    PubMed

    Murphey, Mark D; Foreman, Kristopher L; Klassen-Fischer, Mary K; Fox, Michael G; Chung, Ellen M; Kransdorf, Mark J

    2014-01-01

    Osteonecrosis is common and represents loss of blood supply to a region of bone. Common sites affected include the femoral head, humeral head, knee, femoral/tibial metadiaphysis, scaphoid, lunate, and talus. Symptomatic femoral head osteonecrosis accounts for 10,000-20,000 new cases annually in the United States. In contradistinction, metadiaphyseal osteonecrosis is often occult and asymptomatic. There are numerous causes of osteonecrosis most commonly related to trauma, corticosteroids, and idiopathic. Imaging of osteonecrosis is frequently diagnostic with a serpentine rim of sclerosis on radiographs, photopenia in early disease at bone scintigraphy, and maintained yellow marrow at MR imaging with a serpentine rim of high signal intensity (double-line sign) on images obtained with long repetition time sequences. These radiologic features correspond to the underlying pathology of osseous response to wall off the osteonecrotic process and attempts at repair with vascularized granulation tissue at the reactive interface. The long-term clinical importance of epiphyseal osteonecrosis is almost exclusively based on the likelihood of overlying articular collapse. MR imaging is generally considered the most sensitive and specific imaging modality both for early diagnosis and identifying features that increase the possibility of this complication. Treatment subsequent to articular collapse and development of secondary osteoarthritis typically requires reconstructive surgery. Malignant transformation of osteonecrosis is rare and almost exclusively associated with metadiaphyseal lesions. Imaging features of this dire sequela include aggressive bone destruction about the lesion margin, cortical involvement, and an associated soft-tissue mass. Recognizing the appearance of osteonecrosis, which reflects the underlying pathology, improves radiologic assessment and is important to guide optimal patient management.

  8. Steroid-induced osteonecrosis: a review.

    PubMed

    Cruess, R L

    1981-11-01

    Between 1963 and 1980 cortisone-induced osteonecrosis has been seen in 122 patients at the Royal Victoria Hospital, Montreal. Of these, 68 had had renal homotransplants; the others suffered from a variety of conditions. The femoral head was most commonly affected; the humeral head, distal femur, proximal tibia, talus and capitellum were also involved. There were two patterns of involvement, similar in all locations. The more common is subchondral osteolysis, which may heal without operation. The other is similar to osteochondritis dissecans and requires operation. Alteration in fat metabolism is the most likely cause of the condition. Vascular occlusion and bone death may result from an increase in fat cell size or from fat embolization. Treatment should be conservative as often as possible, but gratifying results have been obtained in those patients requiring surgical procedures.

  9. Kinematics of a Head-Neck Model Simulating Whiplash

    ERIC Educational Resources Information Center

    Colicchia, Giuseppe; Zollman, Dean; Wiesner, Hartmut; Sen, Ahmet Ilhan

    2008-01-01

    A whiplash event is a relative motion between the head and torso that occurs in rear-end automobile collisions. In particular, the large inertia of the head results in a horizontal translation relative to the thorax. This paper describes a simulation of the motion of the head and neck during a rear-end (whiplash) collision. A head-neck model that…

  10. Osteonecrosis of Femoral Head Treated with Extracorporeal Shock Wave Therapy: Analysis of Short-term Clinical Outcomes of Treatment with Radiologic Staging

    PubMed Central

    Lee, Jin-Young; Kwon, Jae-Woo; Park, Jung-Seob; Han, Kyeol; Shin, Woo-jin; Lee, Jeong-Gil

    2015-01-01

    Purpose To evaluate clinical results of extracorporeal shock wave therapy (ESWT) with radiographic staging on patients with avascular necrosis of femoral head (AVNFH). Materials and Methods We evaluated 24 patients diagnosed with AVNFH (32 hip joints) who were treated with ESWT from 1993 to 2012. Average follow-up period was 27 months, and the average age of patients was 47.8 years. The Association Research Circulation Osseous (ARCO) system was used to grade radiographic stage prior to treatment. For this study patients were divided into two groups based on their ARCO stage, group 1 (ARCO stages I and II) and group 2 (ARCO stage III). Comparative analyses were done between the two groups using the visual analogue scale (VAS) score and the Harris hip score (HHS) at pre-treatment and 3, 6, 12, and 24 months after treatment. Failure was defined when radiographic stage progressed or arthroplasty surgery was needed due to clinical exacerbation. Results Both groups showed clinical improvements with VAS scoring at final follow-up (group 1: median 7 to 1.5, P<0.001; group 2: mean 7 to 4, P=0.056). Using HHS, group 1 showed a significant improvement (from 65.5 to 95 [P<0.001]), while no significance was observed for group 2 (P=0.280). At final follow-up, 3 hips from group 1 and one hip from group 2 showed radiographic improvement; however, two patients underwent total hip arthroplasty due to persistent pain and dysfunction. Conclusion ESWT can be considered as an interventional option before surgical treatment in patients with not only early stage AVNFH but also with mid stage. PMID:27536633

  11. Post-traumatic osteonecrosis of the proximal humerus.

    PubMed

    Patel, Shelain; Colaco, Henry B; Elvey, Michael E; Lee, Marcus H

    2015-10-01

    Post-traumatic osteonecrosis of the proximal humerus represents a challenging problem to the surgeon. It is commonly seen following multi-fragmentary fractures of the proximal humerus which may affect the long-term functional recovery after such injuries. This review summarises the current evidence on risk factors, reasons why estimating its epidemiology is difficult, the vascular supply of the humeral head, classification, and management options.

  12. Walking Ahead: The Headed Social Force Model.

    PubMed

    Farina, Francesco; Fontanelli, Daniele; Garulli, Andrea; Giannitrapani, Antonio; Prattichizzo, Domenico

    2017-01-01

    Human motion models are finding an increasing number of novel applications in many different fields, such as building design, computer graphics and robot motion planning. The Social Force Model is one of the most popular alternatives to describe the motion of pedestrians. By resorting to a physical analogy, individuals are assimilated to point-wise particles subject to social forces which drive their dynamics. Such a model implicitly assumes that humans move isotropically. On the contrary, empirical evidence shows that people do have a preferred direction of motion, walking forward most of the time. Lateral motions are observed only in specific circumstances, such as when navigating in overcrowded environments or avoiding unexpected obstacles. In this paper, the Headed Social Force Model is introduced in order to improve the realism of the trajectories generated by the classical Social Force Model. The key feature of the proposed approach is the inclusion of the pedestrians' heading into the dynamic model used to describe the motion of each individual. The force and torque representing the model inputs are computed as suitable functions of the force terms resulting from the traditional Social Force Model. Moreover, a new force contribution is introduced in order to model the behavior of people walking together as a single group. The proposed model features high versatility, being able to reproduce both the unicycle-like trajectories typical of people moving in open spaces and the point-wise motion patterns occurring in high density scenarios. Extensive numerical simulations show an increased regularity of the resulting trajectories and confirm a general improvement of the model realism.

  13. Walking Ahead: The Headed Social Force Model

    PubMed Central

    2017-01-01

    Human motion models are finding an increasing number of novel applications in many different fields, such as building design, computer graphics and robot motion planning. The Social Force Model is one of the most popular alternatives to describe the motion of pedestrians. By resorting to a physical analogy, individuals are assimilated to point-wise particles subject to social forces which drive their dynamics. Such a model implicitly assumes that humans move isotropically. On the contrary, empirical evidence shows that people do have a preferred direction of motion, walking forward most of the time. Lateral motions are observed only in specific circumstances, such as when navigating in overcrowded environments or avoiding unexpected obstacles. In this paper, the Headed Social Force Model is introduced in order to improve the realism of the trajectories generated by the classical Social Force Model. The key feature of the proposed approach is the inclusion of the pedestrians’ heading into the dynamic model used to describe the motion of each individual. The force and torque representing the model inputs are computed as suitable functions of the force terms resulting from the traditional Social Force Model. Moreover, a new force contribution is introduced in order to model the behavior of people walking together as a single group. The proposed model features high versatility, being able to reproduce both the unicycle-like trajectories typical of people moving in open spaces and the point-wise motion patterns occurring in high density scenarios. Extensive numerical simulations show an increased regularity of the resulting trajectories and confirm a general improvement of the model realism. PMID:28076435

  14. Histologic analysis of postmeniscectomy osteonecrosis.

    PubMed

    Higuchi, Hiroshi; Kobayashi, Yasukazu; Kobayashi, Atsushi; Hatayama, Kazuhisa; Kimura, Masashi

    2013-05-01

    Bone marrow signal changes on magnetic resonance imaging (MRI) after meniscectomy have been reported as evidence of postmeniscectomy osteonecrosis, but this pathology is unclear. We conducted a study to follow-up cases with bone marrow signal changes on MRI after meniscectomy and investigate the pathology of underlying lesions. Of 136 patients with no presurgical evidence of osteonecrosis, 29 had juxta-articular bone marrow signal changes on MRI after arthroscopic meniscectomy and subsequently underwent conservative therapy. In 6 of these 29 patients, clinical symptoms and radiographic changes began deteriorating. Based on the Koshino classification, 4 of the 6 patients had Stage-2 knee osteonecrosis and 2 had Stage-3. Arthroscopic and pathologic examinations were performed. Arthroscopic findings were fibrillation (all 6 cases), fissuring (4), ulceration (2), and eburnation (2). Histologic analysis confirmed subchondral bone fractures in all 6 cases, but osteonecrotic lesions were detected only in 2 cases with obvious radiologic deterioration. Postmeniscectomy osteonecrosis might result from subchondral bone fractures. Fracture healing is worse in patients with comorbidities than in those without it; comorbidities might be a risk factor for osteonecrosis.

  15. The pathogenesis of multifocal osteonecrosis

    PubMed Central

    Sun, Wei; Shi, Zhencai; Gao, Fuqiang; Wang, Bailiang; Li, Zirong

    2016-01-01

    Our objective was to study the incidence, etiology, and diagnosis of multifocal osteonecrosis (MFON) and its treatment options to facilitate an earlier diagnosis and to optimize treatment. A radiological investigation was performed in osteonecrosis patients with a high risk of MFON for a more accurate diagnosis between January 2010 and June 2015. For patients with osteonecrosis of both the hip and knee joints or for patients with a history of corticosteroid use or alcohol abuse who had osteonecrosis of one or more joints in the shoulder, ankle, wrist or elbow, magnetic resonance imaging (MRI) was also performed on other joints, regardless of whether these joints were symptomatic. Furthermore, we performed a radiological screening of 102 patients who had a negative diagnosis of MFON but were at a high risk; among them, another 31 MFON cases were successfully identified (30.4%). Thus, the incidence of MFON during the study period increased from 3.1% to 5.2%. Patients diagnosed with osteonecrosis and who are at a high risk of MFON should have their other joints radiologically examined when necessary. This will reduce missed diagnosis of MFON and facilitate an earlier diagnosis and treatment to achieve an optimal outcome. PMID:27404962

  16. The Texas Head Start Metro Models.

    ERIC Educational Resources Information Center

    Riley, Mary Tom, Ed.; Flores, Alfredo R., Ed.

    The Texas Metro Network (TMN) is an informal group of Head Start Directors and Executive Directors organized for the purposes of improving the delivery of training and technical assistance and for assisting communication between large scale Head Start programs in the metropolitan areas of Texas. In pursuit of these aims, each member unit of the…

  17. An internal model of head kinematics predicts the influence of head orientation on reflexive eye movements

    NASA Astrophysics Data System (ADS)

    Zupan, L. H.; Merfeld, D. M.

    2005-09-01

    Our sense of self-motion and self-orientation results from combining information from different sources. We hypothesize that the central nervous system (CNS) uses internal models of the laws of physics to merge cues provided by different sensory systems. Different models that include internal models have been proposed; we focus herein on that referred to as the sensory weighting model (Zupan et al 2002 Biol. Cybern. 86 209-30). For simplicity, we isolate the portion of the sensory weighting model that estimates head angular velocity: it includes an inverse internal model of head kinematics and an 'idiotropic' vector aligned with the main body axis. Following a post-rotatory tilt in the dark, which is a rapid tilt following a constant-velocity rotation about an earth-vertical axis, the inverse internal model is applied to conflicting vestibular signals. Consequently, the CNS computes an inaccurate estimate of head angular velocity that shifts toward alignment with an estimate of gravity. Since reflexive eye movements known as vestibulo-ocular reflexes (VOR) compensate for this estimate of head angular velocity, the model predicts that the VOR rotation axis shifts toward alignment with this estimate of gravity and that the VOR time constant depends on final head orientation. These predictions are consistent with experimental data.

  18. A Personal Computer-Based Head-Spine Model

    DTIC Science & Technology

    1998-09-01

    will be marketed to amusement and theme parks and roller coaster designers to ensure that their roller coasters and mechanical rides are safe. By...14 15 Element Model (original and settled positions) 6-12 Figure 6-15 Head Cervical Spine Simulation- 3G Vertical Accelerations 6-13 Figure 7-1...experimentally determined frequency response of humans to vertical excitation and by creating head-spine models for other primates and comparing the model

  19. [Bionic model for coordinated head-eye motion control].

    PubMed

    Mao, Xiaobo; Chen, Tiejun

    2011-10-01

    The relationships between eye movements and head movements of the primate during gaze shifts are analyzed in detail in the present paper. Applying the mechanisms of neurophysiology to engineering domain, we have improved the robot eye-head coordination. A bionic control strategy of coordinated head-eye motion was proposed. The processes of gaze shifts are composed of an initial fast phase followed by a slow phase. In the fast phase saccade eye movements and slow head movements were combined, which cooperate to bring gaze from an initial resting position toward the new target rapidly, while in the slow phase the gaze stability and target fixation were ensured by the action of the vestibulo-ocular reflex (VOR) where the eyes and head rotate by equal amplitudes in opposite directions. A bionic gaze control model was given. The simulation results confirmed the effectiveness of the model by comparing with the results of neurophysiology experiments.

  20. Osmotic Model to Explain Anomalous Hydraulic Heads

    NASA Astrophysics Data System (ADS)

    Marine, I. Wendell; Fritz, Steven J.

    1981-01-01

    Laboratory experiments have shown that compacted clays act as osmotic membranes when they separate aqueous solutions of unequal ionic concentration. Theoretically, osmotically induced differential hydraulic pressure in groundwater systems can be relatively high. The magnitude depends primarily upon concentration differences across the membrane, type of ions, type of clay, and pore size. In experiments, thin, compacted clay membranes commonly exhibit varying degrees of osmotic efficiency due to ion leak-age through the clay. In natural systems the membrane and the solution containers are not as distinct and well defined as they are in the laboratory. Moreover, the membrane is commonly thick, inhomogeneous, and composite. In a buried Triassic basin at the Savannah River plant near Aiken, South Carolina, it is suspected that osmosis causes the saline water in the basin center to be slightly geopressurized in relation to freshwater in the overlying coastal plain aquifer. Two wells have heads of 7.88 and 12.98 bars (114.3 and 188.3 psi) above the head in the coastal plain aquifer. The head in each of these wells approximates the osmotic equilibrium head calculated from solution concentration of water produced by each well (12,000 and 18,500 mg/l, respectively). Other wells penetrating the top and edge of the Triassic basin probably penetrate a zone where ion leakage gives rise to less saline water. Thus these wells are not geopressurized.

  1. Head Motion Modeling for Human Behavior Analysis in Dyadic Interaction

    PubMed Central

    Xiao, Bo; Georgiou, Panayiotis; Baucom, Brian; Narayanan, Shrikanth S.

    2015-01-01

    This paper presents a computational study of head motion in human interaction, notably of its role in conveying interlocutors’ behavioral characteristics. Head motion is physically complex and carries rich information; current modeling approaches based on visual signals, however, are still limited in their ability to adequately capture these important properties. Guided by the methodology of kinesics, we propose a data driven approach to identify typical head motion patterns. The approach follows the steps of first segmenting motion events, then parametrically representing the motion by linear predictive features, and finally generalizing the motion types using Gaussian mixture models. The proposed approach is experimentally validated using video recordings of communication sessions from real couples involved in a couples therapy study. In particular we use the head motion model to classify binarized expert judgments of the interactants’ specific behavioral characteristics where entrainment in head motion is hypothesized to play a role: Acceptance, Blame, Positive, and Negative behavior. We achieve accuracies in the range of 60% to 70% for the various experimental settings and conditions. In addition, we describe a measure of motion similarity between the interaction partners based on the proposed model. We show that the relative change of head motion similarity during the interaction significantly correlates with the expert judgments of the interactants’ behavioral characteristics. These findings demonstrate the effectiveness of the proposed head motion model, and underscore the promise of analyzing human behavioral characteristics through signal processing methods. PMID:26557047

  2. Evaluation of a laboratory model of human head impact biomechanics

    PubMed Central

    Hernandez, Fidel; Shull, Peter B.; Camarillo, David B.

    2015-01-01

    This work describes methodology for evaluating laboratory models of head impact biomechanics. Using this methodology, we investigated: how closely does twin-wire drop testing model head rotation in American football impacts? Head rotation is believed to cause mild traumatic brain injury (mTBI) but helmet safety standards only model head translations believed to cause severe TBI. It is unknown whether laboratory head impact models in safety standards, like twin-wire drop testing, reproduce six degree-of-freedom (6DOF) head impact biomechanics that may cause mTBI. We compared 6DOF measurements of 421 American football head impacts to twin-wire drop tests at impact sites and velocities weighted to represent typical field exposure. The highest rotational velocities produced by drop testing were the 74th percentile of non-injury field impacts. For a given translational acceleration level, drop testing underestimated field rotational acceleration by 46% and rotational velocity by 72%. Primary rotational acceleration frequencies were much larger in drop tests (~100Hz) than field impacts (~10Hz). Drop testing was physically unable to produce acceleration directions common in field impacts. Initial conditions of a single field impact were highly resolved in stereo high-speed video and reconstructed in a drop test. Reconstruction results reflected aggregate trends of lower amplitude rotational velocity and higher frequency rotational acceleration in drop testing, apparently due to twin-wire constraints and the absence of a neck. These results suggest twin-wire drop testing is limited in modeling head rotation during impact, and motivate continued evaluation of head impact models to ensure helmets are tested under conditions that may cause mTBI. PMID:26117075

  3. Evaluation of a laboratory model of human head impact biomechanics.

    PubMed

    Hernandez, Fidel; Shull, Peter B; Camarillo, David B

    2015-09-18

    This work describes methodology for evaluating laboratory models of head impact biomechanics. Using this methodology, we investigated: how closely does twin-wire drop testing model head rotation in American football impacts? Head rotation is believed to cause mild traumatic brain injury (mTBI) but helmet safety standards only model head translations believed to cause severe TBI. It is unknown whether laboratory head impact models in safety standards, like twin-wire drop testing, reproduce six degree-of-freedom (6DOF) head impact biomechanics that may cause mTBI. We compared 6DOF measurements of 421 American football head impacts to twin-wire drop tests at impact sites and velocities weighted to represent typical field exposure. The highest rotational velocities produced by drop testing were the 74th percentile of non-injury field impacts. For a given translational acceleration level, drop testing underestimated field rotational acceleration by 46% and rotational velocity by 72%. Primary rotational acceleration frequencies were much larger in drop tests (~100 Hz) than field impacts (~10 Hz). Drop testing was physically unable to produce acceleration directions common in field impacts. Initial conditions of a single field impact were highly resolved in stereo high-speed video and reconstructed in a drop test. Reconstruction results reflected aggregate trends of lower amplitude rotational velocity and higher frequency rotational acceleration in drop testing, apparently due to twin-wire constraints and the absence of a neck. These results suggest twin-wire drop testing is limited in modeling head rotation during impact, and motivate continued evaluation of head impact models to ensure helmets are tested under conditions that may cause mTBI.

  4. Evaluation of Femoral Head Necrosis Using a Volumetric Method Based on MRI

    DTIC Science & Technology

    2001-10-25

    hip hemi - arthroplasty . The specimens were trimmed and rounded-up with wax, to take the shape of a sphere. In order to simulate the affected...106 hips with osteonecrosis before treatment with vascularized fibular grafting. The hips were evaluated using the volumetric method. The follow up...Osteonecrosis, MRI, Volumetric Feature Extraction, Automated Diagnosis I.INTRODUCTION Femoral head osteonecrosis is responsible for a large number of hip

  5. What is the pain source? A case report of a patient with low back pain and bilateral hip osteonecrosis

    PubMed Central

    Minkalis, Amy L.; Vining, Robert D.

    2015-01-01

    Background: Low back pain is a common symptom arising from many possible sources and includes the possibility of the contribution of remote pathology. This report describes a patient with bilateral osteonecrosis of the femoral heads presenting with a primary symptom of low back pain. Case presentation: A 37-year-old male presented for evaluation of dominant pain that existed for approximately 6–12 months and was located in the right low back. Milder pain was also reported in the right hip. Low back and hip pain were both aggravated by weight-bearing activities. An evidence-based diagnostic evaluation revealed little indication for a primary pain source originating from low back structures. Radiographs revealed bilateral osteonecrosis with evidence of left femoral head collapse. Conclusion: Hip osteonecrosis may have contributed to an atypical presentation of low back pain due to aberrant localization of pain and/or combined with altered biomechanical loading of musculoskeletal structures. PMID:26500365

  6. Bilateral rapidly destructive arthrosis of the hip joint resulting from subchondral fracture with superimposed secondary osteonecrosis.

    PubMed

    Yamamoto, Takuaki; Schneider, Robert; Iwamoto, Yukihide; Bullough, Peter G

    2010-02-01

    A 57-year-old woman suffered rapid destruction of both hip joints over a 10 months period. At the first visit, her radiographs demonstrated slight joint space narrowing and acetabular cyst formation in both hips. Five months later, joint space narrowing had further progressed, and intra-articular injection of steroid was given in both hips. However, the hip pain gradually became worse. Five months later, both joint spaces had totally disappeared and both femoral heads had undergone massive collapse. At gross examination, both resected femoral heads showed extensive opaque yellow areas consistent with osteonecrosis. Microscopic examination of these areas revealed evidence of both extensive fracture and callus formation, as well as necrosis throughout, indicating that the osteonecrosis observed in this case was a secondary phenomenon superimposed on pre-existing osteoarthritis and subchondral fracture. There were many pseudogranulomatous lesions in the marrow space and necrotic area, where tiny fragments of bone and articular cartilage, surrounded by histiocytes and giant cells, were embedded, such as are typically seen in rapidly destructive arthrosis. No radiologic or morphologic evidence of primary osteonecrosis was noted. This case indicates that at least some cases of rapidly destructive arthritis are the result of subchondral fracture with superimposed secondary osteonecrosis.

  7. Apoptosis of osteocytes in glucocorticoid-induced osteonecrosis of the hip.

    PubMed

    Weinstein, R S; Nicholas, R W; Manolagas, S C

    2000-08-01

    An increase in osteoblast and osteocyte apoptosis has been demonstrated in mice and humans receiving glucocorticoids and may be involved in the pathogenesis of the associated osteonecrosis. To examine the spatial relationship between osteocyte apoptosis and glucocorticoid-induced osteonecrosis, we determined the prevalence of osteocyte apoptosis in whole femoral heads obtained from patients who underwent prosthetic hip replacement because of osteonecrosis due to chronic glucocorticoid treatment (n = 5), alcoholism (n = 3), and trauma (n = 1) as well as in femoral neck cores from patients with sickle cell disease (n = 5). Abundant apoptotic osteocytes and cells lining cancellous bone were found juxtaposed to the subchondral fracture crescent in femurs from the patients with glucocorticoid excess. In contrast, apoptotic bone cells were absent from the specimens taken from patients with trauma or sickle cell disease and were rare with alcohol abuse. These results indicate that glucocorticoid-induced osteonecrosis is a misnomer. The bone is not necrotic; instead, it shows prominent apoptosis of cancellous lining cells and osteocytes. Glucocorticoid-induced osteocyte apoptosis, a cumulative and irreparable defect, could uniquely disrupt the mechanosensory function of the osteocyte network and thus start the inexorable sequence of events leading to collapse of the femoral head.

  8. Modeling transient streaming potentials in falling-head permeameter tests.

    PubMed

    Malama, Bwalya; Revil, André

    2014-01-01

    We present transient streaming potential data collected during falling-head permeameter tests performed on samples of two sands with different physical and chemical properties. The objective of the work is to estimate hydraulic conductivity (K) and the electrokinetic coupling coefficient (Cl ) of the sand samples. A semi-empirical model based on the falling-head permeameter flow model and electrokinetic coupling is used to analyze the streaming potential data and to estimate K and Cl . The values of K estimated from head data are used to validate the streaming potential method. Estimates of K from streaming potential data closely match those obtained from the associated head data, with less than 10% deviation. The electrokinetic coupling coefficient was estimated from streaming potential vs. (1) time and (2) head data for both sands. The results indicate that, within limits of experimental error, the values of Cl estimated by the two methods are essentially the same. The results of this work demonstrate that a temporal record of the streaming potential response in falling-head permeameter tests can be used to estimate both K and Cl . They further indicate the potential for using transient streaming potential data as a proxy for hydraulic head in hydrogeology applications.

  9. Approximate average head models for EEG source imaging.

    PubMed

    Valdés-Hernández, Pedro A; von Ellenrieder, Nicolás; Ojeda-Gonzalez, Alejandro; Kochen, Silvia; Alemán-Gómez, Yasser; Muravchik, Carlos; Valdés-Sosa, Pedro A

    2009-12-15

    We examine the performance of approximate models (AM) of the head in solving the EEG inverse problem. The AM are needed when the individual's MRI is not available. We simulate the electric potential distribution generated by cortical sources for a large sample of 305 subjects, and solve the inverse problem with AM. Statistical comparisons are carried out with the distribution of the localization errors. We propose several new AM. These are the average of many individual realistic MRI-based models, such as surface-based models or lead fields. We demonstrate that the lead fields of the AM should be calculated considering source moments not constrained to be normal to the cortex. We also show that the imperfect anatomical correspondence between all cortices is the most important cause of localization errors. Our average models perform better than a random individual model or the usual average model in the MNI space. We also show that a classification based on race and gender or head size before averaging does not significantly improve the results. Our average models are slightly better than an existing AM with shape guided by measured individual electrode positions, and have the advantage of not requiring such measurements. Among the studied models, the Average Lead Field seems the most convenient tool in large and systematical clinical and research studies demanding EEG source localization, when MRI are unavailable. This AM does not need a strict alignment between head models, and can therefore be easily achieved for any type of head modeling approach.

  10. Inverse Modelling to Obtain Head Movement Controller Signal

    NASA Technical Reports Server (NTRS)

    Kim, W. S.; Lee, S. H.; Hannaford, B.; Stark, L.

    1984-01-01

    Experimentally obtained dynamics of time-optimal, horizontal head rotations have previously been simulated by a sixth order, nonlinear model driven by rectangular control signals. Electromyography (EMG) recordings have spects which differ in detail from the theoretical rectangular pulsed control signal. Control signals for time-optimal as well as sub-optimal horizontal head rotations were obtained by means of an inverse modelling procedures. With experimentally measured dynamical data serving as the input, this procedure inverts the model to produce the neurological control signals driving muscles and plant. The relationships between these controller signals, and EMG records should contribute to the understanding of the neurological control of movements.

  11. Elevation of pro-inflammatory cytokine levels following anti-resorptive drug treatment is required for osteonecrosis development in infectious osteomyelitis

    PubMed Central

    Morita, Mayu; Iwasaki, Ryotaro; Sato, Yuiko; Kobayashi, Tami; Watanabe, Ryuichi; Oike, Takatsugu; Nakamura, Satoshi; Keneko, Yosuke; Miyamoto, Kana; Ishihara, Kazuyuki; Iwakura, Yoichiro; Ishii, Ken; Matsumoto, Morio; Nakamura, Masaya; Kawana, Hiromasa; Nakagawa, Taneaki; Miyamoto, Takeshi

    2017-01-01

    Various conditions, including bacterial infection, can promote osteonecrosis. For example, following invasive dental therapy with anti-bone resorptive agents, some patients develop osteonecrosis in the jaw; however, pathological mechanisms underlying these outcomes remain unknown. Here, we show that administration of anti-resorptive agents such as the bisphosphonate alendronate accelerates osteonecrosis promoted by infectious osteomyelitis. Potent suppression of bone turnover by these types of agents is considered critical for osteonecrosis development; however, using mouse models we found that acceleration of bone turnover by teriparatide injection did not prevent osteonecrosis but rather converted osteoclast progenitors to macrophages expressing inflammatory cytokines, which were required for osteonecrosis development. In fact, we demonstrate that TNFα-, IL-1α/β- or IL-6-deficient mice as well as wild-type mice administered a TNFα-inhibitor were significantly resistant to development of osteonecrosis accompanying infectious myelitis, even under bisphosphonate treatment. Our data provide new insight into mechanisms underlying osteonecrosis and suggest new ways to prevent it. PMID:28387378

  12. Drug induced osteonecrosis of the jaw.

    PubMed

    Hamadeh, Issam S; Ngwa, Bridget A; Gong, Yan

    2015-05-01

    Despite the widespread use of bisphosphonates and their unequivocal efficacy for the treatment of various disease states, osteonecrosis of the jaw remains one of the most feared complications associated with their use. Current evidence, however, suggests that there is also a relationship between occurrence of osteonecrosis of the jaw and use of other classes of pharmacotherapies namely RANKL inhibitors as well as angiogenesis inhibitors. Although these drugs have different mechanisms of action than bisphosphonates, they all seem to interfere with the bone remodeling process i.e. alter the balance between bone resorption and bone formation which may be the most plausible explanation for pathogenesis of osteonecrosis of the jaw. The main objective of this review is to introduce the readership to a number of relatively new medications that may cause osteonecrosis of the jaw. Accordingly, we will summarize latest findings from clinical studies, meta analyses and case reports published in medical literature on this topic. For some of these medications, the evidence may not appear as robust as that for bisphosphonates; yet, the possibility of this adverse event occurring with these non bisphosphonate drugs should never be precluded unless proven otherwise. Thus, it is imperative that health care providers implement preventive measures so as to circumvent the incidence of osteonecrosis of the jaw. In this day of age where medical care is becoming personalized, we will highlight some of significant findings from studies seeking to identify genetic markers that may potentially play a role in development of osteonecrosis of the jaw.

  13. [Osteonecrosis in HIV-infected patients].

    PubMed

    Bottaro, Edgardo G; Figueroa, Raúl H; Scapellato, Pablo G; Vidal, Gabriela I; Rodriguez Brieschke, Maria T; Da Representaçao, Silvia; Seoane, Maria B; Laurido, Marcelo F; Caiafa, Diego; Lopardo, Gustavo; Herrera, Fabian; Cassetti, Isabel

    2004-01-01

    Osteonecrosis, also known as avascular necrosis, is chiefly characterized by death of bone caused by vascular compromise. The true incidence of osteonecrosis in HIV-infected patients is not well known and the pathogenesis remains undefined. Hypothetical risk factors peculiar to HIV-infected individuals that might play a role in the pathogenesis of osteonecrosis include the introduction of protease inhibitors and resulting hyperlipidemia, the presence of anticardiolipin antibodies in serum leading to a hypercoagulable state, immune recovery and vasculitis. Hereby we present a series of 13 HIV-infected patients with osteonecrosis. The most common symptom upon presentation was arthralgia. The majority of the patients had received steroids, 9 had developed hyperlipidemia after the introduction of HAART, 8 were smokers and 4 patients were alcoholics. In 2 patients, seric anticardiolipin antibodies were detected. Twelve patients had AIDS and were on HAART (11 were on protease inhibitors). We believe that osteonecrosis should be included as differential diagnosis of every HIV-infected patient who complains of pain of weight bearing joints. Likewise, it seems prudent to rule out HIV infection in subjects with osteonecrosis.

  14. An FDTD model of scattering from meteor head plasma

    NASA Astrophysics Data System (ADS)

    Marshall, R. A.; Close, S.

    2015-07-01

    We have developed a three-dimensional finite difference time domain (FDTD) model of scattering of radar waves from meteor head plasma. The model treats the meteor head plasma as a cold, collisional, and magnetized plasma, and solves Maxwell's equations and the Langevin equation simultaneously and self-consistently in and around the plasma. We use this model to investigate scattering of radar waves from a meteor head (the "head echo") under a range of plasma densities, meteor scale sizes, and wave frequencies. In this way we relate the radar cross section (RCS) to these variable parameters. We find that computed RCS disagrees with previous analytical theory at certain meteor sizes and densities, in some cases by over an order of magnitude. We find that the calculated meteor head RCS is monotonically related to the "overdense area" of the meteor, defined as the cross-section area of the part of the meteor where the plasma frequency exceeds the wave frequency. These results provides a physical measure of the meteor size and density that can be inferred from measured RCS values from ground-based radars. Meteoroid mass can then be inferred from the meteor plasma distribution using established methods.

  15. Sestamibi and FDG-PET scans to support diagnosis of jaw osteonecrosis.

    PubMed

    Catalano, Lucio; Del Vecchio, Silvana; Petruzziello, Fara; Fonti, Rosa; Salvatore, Barbara; Martorelli, Carmen; Califano, Catello; Caparrotti, Giuseppe; Segreto, Sabrina; Pace, Leonardo; Rotoli, Bruno

    2007-06-01

    Osteonecrosis of the maxillary or mandibular bone is an infrequent but often severe event occurring in patients who undergo prolonged treatment with bisphosphonates. Histology is in some cases mandatory to differentiate it from neoplastic osteolysis, but a biopsy can further contribute to bone damage. Functional imaging obtained by a tracer that shows oncotropic properties, such as Tc99m-sestamibi, in comparison to a non-tumor-specific substance such as FDG-PET, can support the differential diagnosis, thus avoiding invasive procedures. Four patients affected by multiple myeloma and jaw osteonecrosis were prospectively evaluated by sestamibi and FDG-PET scans. Local diagnosis was performed by clinical, radiological and, in some cases, histological evaluations. Each patient was studied by Tc99m-sestamibi, performed by planar anterior and posterior whole-body scans and SPECT of the head and neck, and by PET/CT. Two nuclear medicine physicians, unaware of the final diagnosis, reviewed the images. No sestamibi uptake was evident in the four patients with jaw osteonecrosis, while FDG-PET/CT showed focal uptake in all of them. Our study suggests that the combined use of sestamibi scintigraphy and FDG-PET/CT could support the clinical diagnosis of oral osteonecrosis avoiding the risks of a surgical biopsy. Studies on higher number of patients are necessary to validate these preliminary observations.

  16. A correction on coastal heads for groundwater flow models.

    PubMed

    Lu, Chunhui; Werner, Adrian D; Simmons, Craig T; Luo, Jian

    2015-01-01

    We introduce a simple correction to coastal heads for constant-density groundwater flow models that contain a coastal boundary, based on previous analytical solutions for interface flow. The results demonstrate that accurate discharge to the sea in confined aquifers can be obtained by direct application of Darcy's law (for constant-density flow) if the coastal heads are corrected to ((α + 1)/α)hs  - B/2α, in which hs is the mean sea level above the aquifer base, B is the aquifer thickness, and α is the density factor. For unconfined aquifers, the coastal head should be assigned the value hs1+α/α. The accuracy of using these corrections is demonstrated by consistency between constant-density Darcy's solution and variable-density flow numerical simulations. The errors introduced by adopting two previous approaches (i.e., no correction and using the equivalent fresh water head at the middle position of the aquifer to represent the hydraulic head at the coastal boundary) are evaluated. Sensitivity analysis shows that errors in discharge to the sea could be larger than 100% for typical coastal aquifer parameter ranges. The location of observation wells relative to the toe is a key factor controlling the estimation error, as it determines the relative aquifer length of constant-density flow relative to variable-density flow. The coastal head correction method introduced in this study facilitates the rapid and accurate estimation of the fresh water flux from a given hydraulic head measurement and allows for an improved representation of the coastal boundary condition in regional constant-density groundwater flow models.

  17. Experimental osteonecrosis of the lunate. Revascularization may cause collapse.

    PubMed

    Aspenberg, P; Wang, J S; Jonsson, K; Hagert, C G

    1994-10-01

    Is lunate collapse in Kienböck's disease a consequence of spontaneous revascularization, leading to focal osteolysis? A literature review of osteonecrosis in other locations such as the femoral head and bone allografts showed clearly that the loss of mechanical integrity is due to cellular processes which follow the spontaneous restoration of blood supply. We found no evidence in the literature that the lunate has been shown to be avascular at the time of collapse. On the contrary, increased osteoclastic activity has been reported. We excised and reimplanted the lunate in two monkeys, and found spontaneous revascularization, leading to increased osteoblastic activity. Other parts of the bone were destroyed by osteoclasts, leading to collapse. This histological example suggests that it may be possible to make an analogy with osteonecrosis in other locations. Thus, changes on plain radiography may indicate that the bone is revascularized spontaneously. Before performing operative revascularization of the lunate, one should consider that revascularization is a probable cause for collapse.

  18. Computer model of catalytic combustion/Stirling engine heater head

    NASA Technical Reports Server (NTRS)

    Chu, E. K.; Chang, R. L.; Tong, H.

    1981-01-01

    The basic Acurex HET code was modified to analyze specific problems for Stirling engine heater head applications. Specifically, the code can model: an adiabatic catalytic monolith reactor, an externally cooled catalytic cylindrical reactor/flat plate reactor, a coannular tube radiatively cooled reactor, and a monolithic reactor radiating to upstream and downstream heat exchangers.

  19. Ranking Medical Subject Headings using a factor graph model.

    PubMed

    Wei, Wei; Demner-Fushman, Dina; Wang, Shuang; Jiang, Xiaoqian; Ohno-Machado, Lucila

    2015-01-01

    Automatically assigning MeSH (Medical Subject Headings) to articles is an active research topic. Recent work demonstrated the feasibility of improving the existing automated Medical Text Indexer (MTI) system, developed at the National Library of Medicine (NLM). Encouraged by this work, we propose a novel data-driven approach that uses semantic distances in the MeSH ontology for automated MeSH assignment. Specifically, we developed a graphical model to propagate belief through a citation network to provide robust MeSH main heading (MH) recommendation. Our preliminary results indicate that this approach can reach high Mean Average Precision (MAP) in some scenarios.

  20. Kinematics of a Head-Neck Model Simulating Whiplash

    NASA Astrophysics Data System (ADS)

    Colicchia, Giuseppe; Zollman, Dean; Wiesner, Hartmut; Sen, Ahmet Ilhan

    2008-02-01

    A whiplash event is a relative motion between the head and torso that occurs in rear-end automobile collisions. In particular, the large inertia of the head results in a horizontal translation relative to the thorax. This paper describes a simulation of the motion of the head and neck during a rear-end (whiplash) collision. A head-neck model that qualitatively undergoes the same forces acting in whiplash and shows the same behavior is used to analyze the kinematics of both the head and the cervical spine and the resulting neck loads. The rapid acceleration during a whiplash event causes the extension and flexion of the cervical spine, which in turn can cause dislocated vertebrae, torn ligaments, intervertebral disc herniation, and other trauma that appear to be the likely causes of subsequent painful headache or neck pain symptoms. Thus, whiplash provides a connection between the dynamics of the human body and physics. Its treatment can enliven the usual teaching in kinematics, and both theoretical and experimental approaches provide an interesting biological context to teach introductory principles of mechanics.

  1. Symptomatic osteonecrosis in childhood leukemia survivors: prevalence, risk factors and impact on quality of life in adulthood.

    PubMed

    Girard, Pauline; Auquier, Pascal; Barlogis, Vincent; Contet, Audrey; Poiree, Maryline; Demeocq, François; Berbis, Julie; Herrmann, Iris; Villes, Virginie; Sirvent, Nicolas; Kanold, Justyna; Chastagner, Pascal; Chambost, Hervé; Plantaz, Dominique; Michel, Gérard

    2013-07-01

    Corticosteroid can induce osteonecrosis in children with leukemia. Few studies have been designed to assess the influence of a wide range of cumulative steroid dose on this side effect. Prevalence, risk factors of symptomatic osteonecrosis and its impact on adults' Quality of Life were assessed in 943 patients enrolled in the French "Leucémies de l'Enfant et de l'Adolescent" (LEA) cohort of childhood leukemia survivors. During each medical visit, data on previous osteonecrosis diagnosis were retrospectively collected. Patients without a history but with suggestive symptoms were investigated with magnetic resonance imaging. The total steroid dose in equivalent of prednisone was calculated for each patient and its effect on osteonecrosis occurrence was studied in multivariate models. Cumulative incidence was 1.4% after chemotherapy alone versus 6.8% after transplantation (P<0.001). A higher cumulative steroid dose, age over ten years at diagnosis, and treatment with transplantation significantly increased the risk of osteonecrosis. A higher post-transplant steroid dose and age over ten years at time of transplantation were significant factors in the transplanted group. With patients grouped according to steroid dose quartile, cumulative incidence of osteonecrosis reached 3.8% in the chemotherapy group for a dose beyond 5835 mg/m(2) and 23.8% after transplantation for a post-transplant dose higher than 2055 mg/m(2). Mean physical composite score of Quality of Life was 44.3 in patients with osteonecrosis versus 54.8% in patients without (P<0.001). We conclude that total and post-transplant cumulative steroid dose may predict the risk of osteonecrosis, a rare late effect with a strong negative impact on physical domains of Quality of Life.

  2. Osteonecrosis

    MedlinePlus

    ... Fellows Evidence-Based Practice for Academic Researchers Responsible Data Management in Research Career Planning Treatments Patient and Caregiver ... Fellows Evidence-Based Practice for Academic Researchers Responsible Data Management in Research Career Planning Treatments Patient and Caregiver ...

  3. Pulsed electromagnetic fields stimulation prevents steroid-induced osteonecrosis in rats

    PubMed Central

    2011-01-01

    Background Pulsed electromagnetic fields (PEMF) stimulation has been used successfully to treat nonunion fractures and femoral head osteonecrosis, but relatively little is known about its effects on preventing steroid-induced osteonecrosis. The purpose of the study was to investigate the effects of PEMF stimulation on the prevention of steroid-induced osteonecrosis in rats and explore the underlying mechanisms. Methods Seventy-two male adult Wistar rats were divided into three groups and treated as follows. (1) PEMF stimulation group (PEMF group, n = 24): intravenously injected with lipopolysaccharide (LPS, 10 μg/kg) on day 0 and intramuscularly injected with methylprednisolone acetate (MPSL, 20 mg/kg) on days 1, 2 and 3, then subjected to PEMF stimulation 4 h per day for 1 to 8 weeks. (2) Methylprednisolone-treated group (MPSL group, n = 24): injected the same dose of LPS and MPSL as the PEMF group but without exposure to PEMF. (3) Control group (PS group, n = 24): injected 0.9% saline in the same mode at the same time points. The incidence of osteonecrosis, serum lipid levels and the mRNA and protein expression of transforming growth factor β1 (TGF-β1) in the proximal femur were measured 1, 2, 4 and 8 weeks after the last MPSL (or saline) injection. Results The incidence of osteonecrosis in the PEMF group (29%) was significantly lower than that observed in the MPSL group (75%), while no osteonecrosis was observed in the PS group. The serum lipid levels were significantly lower in the PEMF and PS groups than in the MPSL group. Compared with the MPSL and PS groups, the mRNA expression of TGF-β1 increased, reaching a peak 1 week after PEMF treatment, and remained high for 4 weeks, then declined at 8 weeks, whereas the protein expression of TGF-β1 increased, reaching a peak at 2 weeks after PEMF treatment, and remained high for 8 weeks. Conclusions PEMF stimulation can prevent steroid-induced osteonecrosis in rats, and the underlying mechanisms involve decreased

  4. Etiologic diagnosis of jaw osteonecrosis, other than bisphosphonate and radiotherapy related osteonecrosis.

    PubMed

    Magremanne, M; Picheca, S; Reychler, H

    2014-02-01

    Our purpose was to highlight the various etiologies of maxillo-mandibular osteonecrosis, other than radiotherapy and biphosphonate related osteitis that have been abundantly reported. We performed a PubMed search from August 1, 1972 to August 1, 2012 using the following MeSH terms: "osteonecrosis", "bone", "necrosis", "jaw", "maxilla", "mandible", "palate", "oral", "avascular necrosis", NOT "bisphosphonate" NOT "osteoradionecrosis". Most cases of osteonecrosis were iatrogenic. Viral, mycotic, or bacterial infections were less frequent causes. Cocaine abuse, Wegener's granulomatosis, and N/K lymphoma were other etiologies. It is important to identify the various etiologies rapidly to manage this sometimes very mutilating condition adequately.

  5. Nonvascularized Bone Grafting Defers Joint Arthroplasty in Hip Osteonecrosis

    PubMed Central

    Seyler, Thorsten M.; Marker, David R.; Ulrich, Slif D.; Fatscher, Tobias

    2008-01-01

    A variety of nonvascularized bone grafting techniques have been proposed with varying degrees of success as treatment alternatives for osteonecrosis of the femoral head. The success of these procedures may be enhanced using ancillary growth and differentiation factors. We retrospectively reviewed 33 patients (39 hips) with osteonecrosis of the hip who had nonvascularized bone grafting procedures with supplemental OP-1. We compared the outcomes in this cohort to similar patients treated nonoperatively or with other nonvascularized bone grafting procedures. We used a trapdoor to make a window at the head-neck junction to remove necrotic bone and packed the excavated area with autogenous cancellous bone graft, marrow, and OP-1. The minimum followup was 24 months (mean, 36 months; range, 24–50 months). We performed no further surgery in 25 of 30 small- and medium-sized lesions (80%) but did in two of nine large lesions. Hips with Ficat Stage II disease were not reoperated in 18 of 22 cases during the followup periods. Our short-term results compare similarly to nonoperative treatment and other reports of nonvascularized bone grafting. With the addition of ancillary growth factors, these procedures effectively reduce donor site morbidity and may defer joint arthroplasty in selected patients. Level of Evidence: Level IV, therapeutic study. See the Guidelines for Authors for a complete description of levels of evidence. Electronic supplementary material The online version of this article (doi:10.1007/s11999-008-0211-x) contains supplementary material, which is available to authorized users. PMID:18351424

  6. Osteonecrosis in patients with malignant lymphoma: a review of twenty-five cases

    SciTech Connect

    Engel, I.A.; Straus, D.J.; Lacher, M.; Lane, J.; Smith, J.

    1981-09-01

    A retrospective study of 25 patients with malignant lymphoma who had osteonecrosis of either the femoral or humeral head(s) was undertaken. The common factor present among all patients was the administration of intermittent steroid-containing combination chemotherapy. Seventeen Hodgkin's disease patients received chemotherapy predominantly consisting of an alkylating agent, vincristine, procarbazine, and moderate amounts of prednisone. The non-Hodgkin's lymphoma patients were on various moderate dosage steroid-containing protocols, except three who received prolonged high-dose steroid-containing chemotherapy regimens. Sixteen of the 17 Hodgkin's disease patients and five of the eight non-Hodgkin's lymphoma patients received radiotherapy to the bones that subsequently developed osteonecrosis. Two of the three non-Hodgkin's lymphoma patients who were not irradiated were treated with high-dose steroid-containing chemotherapy regimens. Symptoms developed in patients 12 months to 32 months after completion of chemotherapy and radiotherapy, respectively. Osteonecrosis was a long-term complication of treatment between 1970 and 1979 and occurred in 1.6% of the Hodgkin's disease and 0.12% of the non-Hodgkin's lymphoma patients treated. The authors conclude that the patients at highest risk for this complication are those who receive both radiotherapy to the affected bone(s) and intermittent steroid-containing multiple drug chemotherapy.

  7. Genetic risk factors for glucocorticoid-induced osteonecrosis: a meta-analysis.

    PubMed

    Gong, Li-Li; Fang, Lian-Hua; Wang, He-Yao; Peng, Jian-Hao; Si, Kun; Zhu, Jin; Han, Fei-Fei; Wang, Yue-Hua; Du, Guan-Hua; Pei, Li-Xia; Liu, Li-Hong

    2013-04-01

    Glucocorticoid-induced osteonecrosis is a common and severe adverse event. We conducted a meta-analysis to investigate whether polymorphisms in target genes were associated with the risk of corticosteroid-induced osteonecrosis. Published literature from PubMed and EMBASE were searched for eligible publications. Pooled odds ratio (OR) and 95% confidence interval (CI) were calculated using a fixed- or random-effects model. There were 23 articles with 35 genes described the relationship between polymorphisms and glucocorticoid-induced osteonecrosis. Meta-analyses were carried out for those SNPs with three or more eligible studies, which included four SNPs located in three genes (PAI-1, MTHFR, ABCB1). The meta-analysis revealed that the PAI-1 4G allele was associated with an increased risk of osteonecrosis compared with the 5G allele (combined studies: OR=1.932, 95% CI=1.145-3.261). The OR for the 4G/4G vs. 5G/5G genotype of PAI-1 was 3.217 (95% CI 1.667-6.209 with combined studies), The relative risk of osteonecrosis was increased in the 4G allele vs. 5G/5G and 4G/4G genotype vs. 5G allele, with odds ratios of 2.304 (95% CI=1.235-4.299) and 2.307 (95% CI=1.527-3.485) in combined studies, respectively. The ABCB1 C3435T genotype distributions available confirmed that the C allele increased osteonecrosis risk compared with the T allele (OR 1.668, 95% CI=1.214-2.293) and TT genotype (OR 2.946, 95% CI=1.422-6.101). There was no evidence for significant association between MTHFR C677T and ABCB1 G2677T/A polymorphisms and risk of osteonecrosis. Results of this meta-analysis indicate that the PAI-1 4G/5G and ABCB1 C3435T polymorphisms may be risk factors for osteonecrosis.

  8. The validation and application of a finite element human head model for frontal skull fracture analysis.

    PubMed

    Asgharpour, Z; Baumgartner, D; Willinger, R; Graw, M; Peldschus, S

    2014-05-01

    Traumatic head injuries can result from vehicular accidents, sports, falls or assaults. The current advances in computational methods and the detailed finite element models of the human head provide a significant opportunity for biomechanical study of human head injuries. The biomechanical characteristics of the human head through head impact scenarios can be studied in detail by using the finite element models. Skull fracture is one of the most frequent occurring types of head injuries. The purpose of this study is to analyse the experimental head impacts on cadavers by means of the Strasbourg University Finite Element Head Model (SUFEHM). The results of the numerical model and experimental data are compared for validation purpose. The finite element model has also been applied to predict the skull bone fracture in frontal impacts. The head model includes the scalp, the facial bone, the skull, the cerebral spinal fluid, the meninges, the cerebrum and the cerebellum. The model is used to simulate the experimental frontal head impact tests using a cylindrical padded impactor. Results of the computational simulation shows that the model correlated well with a number of experimental data and a global fracture pattern has been predicted well by the model. Therefore the presented numerical model could be used for reconstruction of head impacts in different impact conditions also the forensic application of the head model would provide a tool for investigation of the causes and mechanism of head injuries.

  9. Development of a Finite Element Head Model for the Study of Impact Head Injury

    PubMed Central

    Yang, Bin; Tse, Kwong-Ming; Chen, Ning; Tan, Long-Bin; Zheng, Qing-Qian; Yang, Hui-Min; Hu, Min; Pan, Gang; Lee, Heow-Pueh

    2014-01-01

    This study is aimed at developing a high quality, validated finite element (FE) human head model for traumatic brain injuries (TBI) prediction and prevention during vehicle collisions. The geometry of the FE model was based on computed tomography (CT) and magnetic resonance imaging (MRI) scans of a volunteer close to the anthropometry of a 50th percentile male. The material and structural properties were selected based on a synthesis of current knowledge of the constitutive models for each tissue. The cerebrospinal fluid (CSF) was simulated explicitly as a hydrostatic fluid by using a surface-based fluid modeling method. The model was validated in the loading condition observed in frontal impact vehicle collision. These validations include the intracranial pressure (ICP), brain motion, impact force and intracranial acceleration response, maximum von Mises stress in the brain, and maximum principal stress in the skull. Overall results obtained in the validation indicated improved biofidelity relative to previous FE models, and the change in the maximum von Mises in the brain is mainly caused by the improvement of the CSF simulation. The model may be used for improving the current injury criteria of the brain and anthropometric test devices. PMID:25405201

  10. Development of skull fracture criterion based on real-world head trauma simulations using finite element head model.

    PubMed

    Sahoo, Debasis; Deck, Caroline; Yoganandan, Narayan; Willinger, Rémy

    2016-04-01

    The objective of this study was to enhance an existing finite element (FE) head model with composite modeling and a new constitutive law for the skull. The response of the state-of-the-art FE head model was validated in the time domain using data from 15 temporo-parietal impact experiments, conducted with postmortem human surrogates. The new model predicted skull fractures observed in these tests. Further, 70 well-documented head trauma cases were reconstructed. The 15 experiments and 70 real-world head trauma cases were combined to derive skull fracture injury risk curves. The skull internal energy was found to be the best candidate to predict skull failure based on an in depth statistical analysis of different mechanical parameters (force, skull internal energy), head kinematic-based parameter, the head injury criterion (HIC), and skull fracture correlate (SFC). The proposed tolerance limit for 50% risk of skull fracture was associated with 453mJ of internal energy. Statistical analyses were extended for individual impact locations (frontal, occipital and temporo-parietal) and separate injury risk curves were obtained. The 50% risk of skull fracture for each location: frontal: 481mJ, occipital: 457mJ, temporo-parietal: 456mJ of skull internal energy.

  11. Ellipsoidal head model for fetal magnetoencephalography: forward and inverse solutions

    NASA Astrophysics Data System (ADS)

    Gutiérrez, David; Nehorai, Arye; Preissl, Hubert

    2005-05-01

    Fetal magnetoencephalography (fMEG) is a non-invasive technique where measurements of the magnetic field outside the maternal abdomen are used to infer the source location and signals of the fetus' neural activity. There are a number of aspects related to fMEG modelling that must be addressed, such as the conductor volume, fetal position and orientation, gestation period, etc. We propose a solution to the forward problem of fMEG based on an ellipsoidal head geometry. This model has the advantage of highlighting special characteristics of the field that are inherent to the anisotropy of the human head, such as the spread and orientation of the field in relationship with the localization and position of the fetal head. Our forward solution is presented in the form of a kernel matrix that facilitates the solution of the inverse problem through decoupling of the dipole localization parameters from the source signals. Then, we use this model and the maximum likelihood technique to solve the inverse problem assuming the availability of measurements from multiple trials. The applicability and performance of our methods are illustrated through numerical examples based on a real 151-channel SQUID fMEG measurement system (SARA). SARA is an MEG system especially designed for fetal assessment and is currently used for heart and brain studies. Finally, since our model requires knowledge of the best-fitting ellipsoid's centre location and semiaxes lengths, we propose a method for estimating these parameters through a least-squares fit on anatomical information obtained from three-dimensional ultrasound images.

  12. 3D head model classification using optimized EGI

    NASA Astrophysics Data System (ADS)

    Tong, Xin; Wong, Hau-san; Ma, Bo

    2006-02-01

    With the general availability of 3D digitizers and scanners, 3D graphical models have been used widely in a variety of applications. This has led to the development of search engines for 3D models. Especially, 3D head model classification and retrieval have received more and more attention in view of their many potential applications in criminal identifications, computer animation, movie industry and medical industry. This paper addresses the 3D head model classification problem using 2D subspace analysis methods such as 2D principal component analysis (2D PCA[3]) and 2D fisher discriminant analysis (2DLDA[5]). It takes advantage of the fact that the histogram is a 2D image, and we can extract the most useful information from these 2D images to get a good result accordingingly. As a result, there are two main advantages: First, we can perform less calculation to obtain the same rate of classification; second, we can reduce the dimensionality more than PCA to obtain a higher efficiency.

  13. Animal models of head and neck squamous cell carcinoma.

    PubMed

    Supsavhad, Wachiraphan; Dirksen, Wessel P; Martin, Chelsea K; Rosol, Thomas J

    2016-04-01

    Head and neck squamous cell carcinoma (HNSCC) is the most common oral cancer worldwide. Local bone invasion into the maxilla or mandible and metastasis to regional lymph nodes often result in a poor prognosis, decreased quality of life and shortened survival time for HNSCC patients. Poor response to treatment and clinical outcomes are the major concerns in this aggressive cancer. Multiple animal models have been developed to replicate spontaneous HNSCC and investigate genetic alterations and novel therapeutic targets. This review provides an overview of HNSCC as well as the traditional animal models used in HNSCC preclinical research. The value and challenges of each in vivo model are discussed. Similarity between HNSCC in humans and cats and the possibility of using spontaneous feline oral squamous cell carcinoma (FOSCC) as a model for HNSCC in translational research are highlighted.

  14. Stage-related results in treatment of hip osteonecrosis with core-decompression and autologous mesenchymal stem cells.

    PubMed

    Persiani, Pietro; De Cristo, Claudia; Graci, Jole; Noia, Giovanni; Gurzì, Michele; Villani, Ciro

    2015-09-01

    Our aim is to analyse the clinical outcome of a series of patients affected by avascular necrosis of the femoral head and treated with core-decompression technique and autologous stromal cells of the bone marrow.We enrolled in our study 29 patients with 31 hips in total affected by avascular necrosis of the femoral head. The clinical and radiological outcome has been assessed through self-administered questionnaires (HHS, VAS and SF12) X-ray and Magnetic Resonance.Of all the examined hips, 25 showed a relief of the symptoms and a resolution of the osteonecrosis, 11 of these were at Stage I and 14 at Stage II. The progression of the disease occurred in 6 hips (2 Stage II, 2 Stage III and 2 Stage IV). Our results show a significant decrease in joint pain level and a success in avoiding or delaying the need of hip replacement in early stages of osteonecrosis.

  15. A conceptual model of emergency physician decision making for head computed tomography in mild head injury.

    PubMed

    Probst, Marc A; Kanzaria, Hemal K; Schriger, David L

    2014-06-01

    The use of computed tomographic scanning in blunt head trauma has increased dramatically in recent years without an accompanying rise in the prevalence of injury or hospital admission for serious conditions. Because computed tomography is neither harmless nor inexpensive, researchers have attempted to optimize utilization, largely through research that describes which clinical variables predict intracranial injury, and use this information to develop clinical decision instruments. Although such techniques may be useful when the benefits and harms of each strategy (neuroimaging vs observation) are quantifiable and amenable to comparison, the exact magnitude of these benefits and harms remains unknown in this clinical scenario. We believe that most clinical decision instrument development efforts are misguided insofar as they ignore critical, nonclinical factors influencing the decision to image. In this article, we propose a conceptual model to illustrate how clinical and nonclinical factors influence emergency physicians making this decision. We posit that elements unrelated to standard clinical factors, such as personality of the physician, fear of litigation and of missed diagnoses, patient expectations, and compensation method, may have equal or greater impact on actual decision making than traditional clinical factors. We believe that 3 particular factors deserve special consideration for further research: fear of error/malpractice, financial incentives, and patient engagement. Acknowledgement and study of these factors will be essential if we are to understand how emergency physicians truly make these decisions and how test-ordering behavior can be modified.

  16. Improved transcranial magnetic stimulation coil design with realistic head modeling

    NASA Astrophysics Data System (ADS)

    Crowther, Lawrence; Hadimani, Ravi; Jiles, David

    2013-03-01

    We are investigating Transcranial magnetic stimulation (TMS) as a noninvasive technique based on electromagnetic induction which causes stimulation of the neurons in the brain. TMS can be used as a pain-free alternative to conventional electroconvulsive therapy (ECT) which is still widely implemented for treatment of major depression. Development of improved TMS coils capable of stimulating subcortical regions could also allow TMS to replace invasive deep brain stimulation (DBS) which requires surgical implantation of electrodes in the brain. Our new designs allow new applications of the technique to be established for a variety of diagnostic and therapeutic applications of psychiatric disorders and neurological diseases. Calculation of the fields generated inside the head is vital for the use of this method for treatment. In prior work we have implemented a realistic head model, incorporating inhomogeneous tissue structures and electrical conductivities, allowing the site of neuronal activation to be accurately calculated. We will show how we utilize this model in the development of novel TMS coil designs to improve the depth of penetration and localization of stimulation produced by stimulator coils.

  17. Osteonecrosis of jaw associated with bisphosphonate use

    PubMed Central

    Rastogi, Ashu; Rattan, Vidya; Bhadada, Sanjay Kumar

    2012-01-01

    Bisphosphonates are associated with osteonecrosis of the jaw (ONJ) that is defined as an area of exposed, nonvital bone in the maxilla or mandible persisting over 6–8 weeks. We describe a case of 55-year-old female who developed ONJ after tooth extraction and had been receiving oral ibandronate for osteoporosis. Diagnosis of ONJ was confirmed on CT scan. The patient was managed conservatively as she denied teriparatide therapy because of cost constraints. PMID:22629519

  18. Clinical and motion studies of the Bateman bipolar prosthesis in osteonecrosis of the hip.

    PubMed

    Mess, D; Barmada, R

    1990-02-01

    Forty-seven hips in 38 patients with femoral head osteonecrosis were reviewed for a mean follow-up period of 2.6 years. The average preoperative Harris hip score was 24.7; postoperatively, the average score was 84.5. Cineroentgenographic motion studies were carried out on 14 hips and revealed motion at both the inner and outer bearing up to seven years postoperatively. In the unloaded mode, inner- and outer-bearing motion were equal. In the weight-bearing position, inner-bearing motion increased significantly while outer-bearing motion decreased. Only one case of acetabular wear or protrusio was noted.

  19. Bisphophonates related osteonecrosis of the jaw

    PubMed Central

    Gupta, Swati; Gupta, Hemant; Mandhyan, Devendra; Srivastava, Sanjeev

    2013-01-01

    Objective: With sporadic reporting of BPs related osteonecrosis of jaw and in absence of definitive guidelines regarding the management of such patients, the dentists and the oral and maxillofacial surgeons need to be updated about this issue. The objective of this article was to produce an updated bibliographic review of BPs related ONJ. This paper reviews the literature regarding the same for better understanding of the problem and its management. Background: Bisphosphonates (BPs) are potent inhibitors of bone resorption and are widely used in the treatment of osteoporosis and other diseases that cause bone mass loss, such as Paget's disease, bone metastases, and multiple myeloma, to prevent pathological fractures. With increasing use, evidence is emerging that patients taking BP drugs are at risk of developing osteonecrosis of the jaws (ONJs), sometimes occurring spontaneously, but more commonly following dental extractions or oral bone surgery. Materials and Methods: A bibliographic search was carried out using PubMed, Medline, and search engines ending in April, 2013. The search terms used were: Oral BPs, dental implants, and osteonecrosis. Conclusion: On the basis of available literature, the management of patients on bisphosphonates requiring dental treatment is classified according to the duration of BPs treatment, method of administration of BPs etc. Dental treatments when planned carefully in such patients have a fair to good prognosis. PMID:24665168

  20. Head modeling for realistic electrical brain activity mapping identification of a multimodal neuroimaging protocol.

    PubMed

    Vatta, F; Bruno, P; Di Salle, F; Esposito, F; Meneghini, F; Mininel, S; Rodaro, M

    2008-01-01

    Realistic electrical brain activity mapping implies reconstructing and visualizing sources of electrical brain activity within the specific patient's head. This requires the assumption of a precise and realistic volume conductor model of the specific subject's head, i.e., a 3-D representation of the head's electrical properties in terms of shape and electrical conductivities. Source reconstruction accuracy is influenced by errors committed in head modeling. Clinical images, MRI and CT, are used to identify the head structures to be included in the volume conductor head model. Modeling accuracy mainly relies on the correct image-based identification of head structures, characterized by different electrical conductivities, to be included as separate compartments in the model. This paper analyzes the imaging protocols used in clinical practice to define the most suitable procedures for identification of the various head structures necessary to build an accurate head model also in the presence of morphologic brain pathologies. Furthermore, tissues anisotropy is discussed and identified as well. With this work we have identified a protocol for the acquisition of multimodal patient's imaging data for realistic electrical brain activity mapping purposes, able to account for pathological conditions and for head tissues anisotropy.

  1. Low resolution brain electromagnetic tomography in a realistic geometry head model: a simulation study

    NASA Astrophysics Data System (ADS)

    Ding, Lei; Lai, Yuan; He, Bin

    2005-01-01

    It is of importance to localize neural sources from scalp recorded EEG. Low resolution brain electromagnetic tomography (LORETA) has received considerable attention for localizing brain electrical sources. However, most such efforts have used spherical head models in representing the head volume conductor. Investigation of the performance of LORETA in a realistic geometry head model, as compared with the spherical model, will provide useful information guiding interpretation of data obtained by using the spherical head model. The performance of LORETA was evaluated by means of computer simulations. The boundary element method was used to solve the forward problem. A three-shell realistic geometry (RG) head model was constructed from MRI scans of a human subject. Dipole source configurations of a single dipole located at different regions of the brain with varying depth were used to assess the performance of LORETA in different regions of the brain. A three-sphere head model was also used to approximate the RG head model, and similar simulations performed, and results compared with the RG-LORETA with reference to the locations of the simulated sources. Multi-source localizations were discussed and examples given in the RG head model. Localization errors employing the spherical LORETA, with reference to the source locations within the realistic geometry head, were about 20-30 mm, for four brain regions evaluated: frontal, parietal, temporal and occipital regions. Localization errors employing the RG head model were about 10 mm over the same four brain regions. The present simulation results suggest that the use of the RG head model reduces the localization error of LORETA, and that the RG head model based LORETA is desirable if high localization accuracy is needed.

  2. Adalimumab: Another Medication Related to Osteonecrosis of the Jaws?

    PubMed Central

    Cassoni, Andrea; Romeo, Umberto; Terenzi, Valentina; Della Monaca, Marco; Rajabtork Zadeh, Oriana; Raponi, Ingrid; Fadda, Maria Teresa; Polimeni, Antonella; Valentini, Valentino

    2016-01-01

    Objective. The acronym MRONJ has been created in order to identify “Medication-Related Osteonecrosis of the Jaw,” observed after the use of Bisphosphonates, RANK ligand inhibitor, and antiangiogenic medications. Only a case of osteonecrosis of the jaw in a Chron's disease patient following a course of Bisphosphonate and Adalimumab therapy has been recently described, so that it has been supposed that also this medication could promote manifestation of osteonecrosis. Clinical Case. On August, 2014, a 63-year-old female with a history of idiopathic arthritis treated with medical treatment with Adalimumab from 2010 to 2013 presented referring pain in the right mandible. Results. This patient presented with nonexposed osteonecrosis of the jaw after placement, on September, 2010, of four titanium fixtures in the mandible. Conclusions. The authors suggest that the biologic therapy with an anti-TNF-α antibody might promote the manifestation of osteonecrosis and compromise oral healing capacity of the bone. PMID:27088019

  3. Adalimumab: Another Medication Related to Osteonecrosis of the Jaws?

    PubMed

    Cassoni, Andrea; Romeo, Umberto; Terenzi, Valentina; Della Monaca, Marco; Rajabtork Zadeh, Oriana; Raponi, Ingrid; Fadda, Maria Teresa; Polimeni, Antonella; Valentini, Valentino

    2016-01-01

    Objective. The acronym MRONJ has been created in order to identify "Medication-Related Osteonecrosis of the Jaw," observed after the use of Bisphosphonates, RANK ligand inhibitor, and antiangiogenic medications. Only a case of osteonecrosis of the jaw in a Chron's disease patient following a course of Bisphosphonate and Adalimumab therapy has been recently described, so that it has been supposed that also this medication could promote manifestation of osteonecrosis. Clinical Case. On August, 2014, a 63-year-old female with a history of idiopathic arthritis treated with medical treatment with Adalimumab from 2010 to 2013 presented referring pain in the right mandible. Results. This patient presented with nonexposed osteonecrosis of the jaw after placement, on September, 2010, of four titanium fixtures in the mandible. Conclusions. The authors suggest that the biologic therapy with an anti-TNF-α antibody might promote the manifestation of osteonecrosis and compromise oral healing capacity of the bone.

  4. Osteonecrosis of the mandible associated with bevacizumab therapy.

    PubMed

    Santos-Silva, Alan Roger; Belizário Rosa, Giuliano Augusto; Castro Júnior, Gilberto de; Dias, Reinaldo Brito; Prado Ribeiro, Ana Carolina; Brandão, Thaís Bianca

    2013-06-01

    Bevacizumab is a humanized antibody that blocks vascular endothelial growth factor and is of great value for the treatment of advanced cancer. Several adverse effects following its administration have been reported. To date, only 8 cases of osteonecrosis of the jaws associated with bevacizumab (without any association with bisphosphonates) have been reported. The aim of this article was to describe an original case of bevacizumab-related osteonecrosis of the jaw. A 61-year-old man diagnosed with advanced renal cell carcinoma was undergoing treatment with intravenous bevacizumab and temsirolimus when he spontaneously developed mandible osteonecrosis, which resolved after 3 months of conservative management. The present case reinforces recent speculation that the anti-angiogenic properties of bevacizumab may represent a potential new source of osteonecrosis of the jaws in patients undergoing cancer treatment. Multidisciplinary teams in cancer care should be aware of the possible association between osteonecrosis of the jaw and bevacizumab therapy.

  5. A Cardiovascular Mathematical Model of Graded Head-Up Tilt

    PubMed Central

    Lim, Einly; Chan, Gregory S. H.; Dokos, Socrates; Ng, Siew C.; Latif, Lydia A.; Vandenberghe, Stijn; Karunanithi, Mohan; Lovell, Nigel H.

    2013-01-01

    A lumped parameter model of the cardiovascular system has been developed and optimized using experimental data obtained from 13 healthy subjects during graded head-up tilt (HUT) from the supine position to . The model includes descriptions of the left and right heart, direct ventricular interaction through the septum and pericardium, the systemic and pulmonary circulations, nonlinear pressure volume relationship of the lower body compartment, arterial and cardiopulmonary baroreceptors, as well as autoregulatory mechanisms. A number of important features, including the separate effects of arterial and cardiopulmonary baroreflexes, and autoregulation in the lower body, as well as diastolic ventricular interaction through the pericardium have been included and tested for their significance. Furthermore, the individual effect of parameter associated with heart failure, including LV and RV contractility, baseline systemic vascular resistance, pulmonary vascular resistance, total blood volume, LV diastolic stiffness and reflex gain on HUT response have also been investigated. Our fitted model compares favorably with our experimental measurements and published literature at a range of tilt angles, in terms of both global and regional hemodynamic variables. Compared to the normal condition, a simulated congestive heart failure condition produced a blunted response to HUT with regards to the percentage changes in cardiac output, stroke volume, end diastolic volume and effector response (i.e., heart contractility, venous unstressed volume, systemic vascular resistance and heart rate) with progressive tilting. PMID:24204817

  6. Ultrahigh head pump/turbine development program: Volume 5, Model tests: Basic performance: Final report

    SciTech Connect

    Yokoyama, T.

    1987-01-01

    Pump/turbine model tests for the Ultra-High Head Pump/Turbine Development Program were conducted for evaluating and refining the pump/turbine design, rated speed 720 rpm, net head 1450, output 655 MW on the scale model at Hitachi Hydraulic Research Laboratory. The basic testing resulted in verification of the design, analysis, and performance of the high head pump/turbine.

  7. Characterizing Discourse Deficits Following Penetrating Head Injury: A Preliminary Model

    ERIC Educational Resources Information Center

    Coelho, Carl; Le, Karen; Mozeiko, Jennifer; Hamilton, Mark; Tyler, Elizabeth; Krueger, Frank; Grafman, Jordan

    2013-01-01

    Purpose: Discourse analyses have demonstrated utility for delineating subtle communication deficits following closed head injuries (CHIs). The present investigation examined the discourse performance of a large group of individuals with penetrating head injury (PHI). Performance was also compared across 6 subgroups of PHI based on lesion locale. A…

  8. Analysis of finite element models for head injury investigation: reconstruction of four real-world impacts.

    PubMed

    Franklyn, Melanie; Fildes, Brian; Zhang, Liying; Yang, King; Sparke, Laurie

    2005-11-01

    Previous studies have shown that both excessive linear and rotational accelerations are the cause of head injuries. Although the head injury criterion has been beneficial as an indicator of head injury risk, it only considers linear acceleration, so there is a need to consider both types of motion in future safety standards. Advanced models of the head/brain complex have recently been developed to gain a better understanding of head injury biomechanics. While these models have been verified against laboratory experimental data, there is a lack of suitable real-world data available for validation. Hence, using two computer models of the head/brain, the objective of the current study was to reconstruct four real-world crashes with known head injury outcomes in a full-vehicle crash laboratory, simulate head/brain responses using kinematics obtained during these reconstructions, and to compare the results predicted by the models against the actual injuries sustained by the occupant. Cases where the occupant sustained no head injuries (AIS 0) and head injuries of severity AIS 4, AIS 5, and multiple head injuries were selected. Data collected from a 9-accelerometer skull were input into the Wayne State University Head Injury Model (WSUHIM) and the NHTSA Simulated Injury Monitor (SIMon). The results demonstrated that both models were able to predict varying injury severities consistent with the difference in AIS injury levels in the real-world cases. The WSUHIM predicted a slightly higher injury threshold than the SIMon, probably due to the finer mesh and different software used for the simulations, and could also determine regions of the brain which had been injured. With further validation, finite element models can be used to establish an injury criterion for each type of brain injury in the future.

  9. Development and validation of a realistic head model for EEG

    NASA Astrophysics Data System (ADS)

    Bangera, Nitin Bhalchandra

    The utility of extracranial electrical or magnetic field recordings (EEG or MEG) is greatly enhanced if the generators of the bioelectromagnetic fields can be determined accurately from the measured fields. This procedure, known as the 'inverse method,' depends critically on calculations of the projection from generators in the brain to the EEG and MEG sensors. Improving and validating this calculation, known as the 'forward solution,' is the focus of this dissertation. The improvements involve more accurate modeling of the structures of the brain and thus understanding how current flows within the brain as a result of addition of structures in the forward model. Validation compares calculations using different forward models to the experimental results obtained by stimulating with implanted dipole electrodes. The human brain tissue displays inhomogeneity in electrical conductivity and also displays anisotropy, notably in the skull and brain white matter. In this dissertation, a realistic head model has been implemented using the finite element method to calculate the effects of inhomogeneity and anisotropy in the human brain. Accurate segmentation of the brain tissue type is implemented using a semi-automatic method to segment multimodal imaging data from multi-spectral MRI scans (different flip angles) in conjunction with the regular T1-weighted scans and computed x-ray tomography images. The electrical conductivity in the anisotropic white matter tissue is quantified from diffusion tensor MRI. The finite element model is constructed using AMIRA, a commercial segmentation and visualization tool and solved using ABAQUS, a commercial finite element solver. The model is validated using experimental data collected from intracranial stimulation in medically intractable epileptic patients. Depth electrodes are implanted in medically intractable epileptic patients in order to direct surgical therapy when the foci cannot be localized with the scalp EEG. These patients

  10. A Drosophila model of closed head traumatic brain injury.

    PubMed

    Katzenberger, Rebeccah J; Loewen, Carin A; Wassarman, Douglas R; Petersen, Andrew J; Ganetzky, Barry; Wassarman, David A

    2013-10-29

    Traumatic brain injury (TBI) is a substantial health issue worldwide, yet the mechanisms responsible for its complex spectrum of pathologies remains largely unknown. To investigate the mechanisms underlying TBI pathologies, we developed a model of TBI in Drosophila melanogaster. The model allows us to take advantage of the wealth of experimental tools available in flies. Closed head TBI was inflicted with a mechanical device that subjects flies to rapid acceleration and deceleration. Similar to humans with TBI, flies with TBI exhibited temporary incapacitation, ataxia, activation of the innate immune response, neurodegeneration, and death. Our data indicate that TBI results in death shortly after a primary injury only if the injury exceeds a certain threshold and that age and genetic background, but not sex, substantially affect this threshold. Furthermore, this threshold also appears to be dependent on the same cellular and molecular mechanisms that control normal longevity. This study demonstrates the potential of flies for providing key insights into human TBI that may ultimately provide unique opportunities for therapeutic intervention.

  11. Identification of femoral head center of bipolar hemiarthroplasy in radiostereometric analysis with elementary geometrical shape models.

    PubMed

    Tsukanaka, Masako; Röhrl, Stephan M; von Schewelov, Thord; Nordsletten, Lars

    2016-02-08

    Elementary geometrical shape (EGS) models are useful in radiostereometric analysis (RSA) on hip stems because tantalum markers attached to the stems can be omitted. In order to create an EGS model of a femoral stem, the center of the femoral head has to be identified. The contour of the femoral head is recommended to be used. However, the contour of the femoral head cannot be detected exclusively by computer if it is combined with a bipolar head or a metal cup. We therefore hypothesized that the contour of the outer head of bipolar hemiarthroplasty can be included in the EGS model as well as the femoral head contour. We calculated the time required for the detection of the contour, the precision of analysis and the stem micromotion at 2 years using the two different methods in the same picture set and compared the results. The detection of the bipolar head contour was 10 times faster than that of the femoral head contour. The precision for subsidence was 0.16 mm in EGS RSA with the femoral head contour, and 0.15 mm with the bipolar head contour (p=0.68). The precisions were comparable and clinically acceptable. There was no significant difference between the results of the 2-year micromotion with the two different methods. We conclude that this new method is applicable to measure stem micromotion of hemi-arthroplasty with EGS RSA and the method facilitates the Radiostereometric analysis.

  12. Hip Osteonecrosis Is Associated with Increased Plasma IL-33 Level

    PubMed Central

    Ma, Jinhui; Guo, Wanshou; Li, Zirong; Li, Shirui; Wang, Peng

    2017-01-01

    The recently discovered IL-33 as an IL-1 cytokine family member has been proved to be specifically released from osteonecrotic bones. We aimed to investigate the potential role of IL-33 in the development of osteonecrosis of femoral head (ONFH). Forty patients diagnosed with ONFH and forty age-, sex-, and body mass index- (BMI-) matched healthy subjects were included in this prospective study between March 2016 and September 2016. A commercially available ELISA kit was used to test the level of plasma IL-33. The IL-33 levels were compared among different ARCO stages, CJFH types, and etiology groups. Plasma IL-33 levels were significantly higher in the ONFH patients than that in the control subjects. The levels of IL-33 did not differ significantly among the ONFH patients with different ARCO stages. The IL-33 levels of patients with CJFH type L3 were significantly higher than that of patients with types L1 and L2. No significant differences were observed in IL-33 levels between steroid-induced, alcohol-induced, and idiopathic patients. Our findings seem to indicate that IL-33 effects may be detrimental during ONFH, which appeared to be associated with the prognosis of ONFH. The IL-33 deserves particular attention in the pathogenesis of ONFH. PMID:28167850

  13. Closed-Head TBI Model of Multiple Morbidity.

    PubMed

    Thompson, Floyd J; Hou, Jiamei; Bose, Prodip K

    2016-01-01

    Successful therapy for TBI disabilities awaits refinement in the understanding of TBI neurobiology, quantitative measurement of treatment-induced incremental changes in recovery trajectories, and effective translation to human TBI using quantitative methods and protocols that were effective to monitor recovery in preclinical models. Details of the specific neurobiology that underlies these injuries and effective quantitation of treatment-induced changes are beginning to emerge utilizing a variety of preclinical and clinical models (for reviews see (Morales et al., Neuroscience 136:971-989, 2005; Fujimoto et al., Neurosci Biobehav Rev 28:365-378, 2004; Cernak, NeuroRx 2:410-422, 2005; Smith et al., J Neurotrauma 22:1485-1502, 2005; Bose et al., J Neurotrauma 30:1177-1191, 2013; Xiong et al., Nat Rev Neurosci 14:128-142, 2013; Xiong et al., Expert Opin Emerg Drugs 14:67-84, 2009; Johnson et al., Handb Clin Neurol 127:115-128, 2015; Bose et al., Brain neurotrauma: molecular, neuropsychological, and rehabilitation aspects, CRC Press/Taylor & Francis, Boca Raton, 2015)). Preclinical models of TBI, essential for the efficient study of TBI neurobiology, benefit from the setting of controlled injury and optimal opportunities for biometric quantitation of injury and treatment-induced changes in the trajectories of disability. Several preclinical models are currently used, and each offer opportunities for study of different aspects of TBI primary and secondary injuries (for review see (Morales et al., Neuroscience 136:971-989, 2005; Xiong et al., Nat Rev Neurosci 14:128-142, 2013; Xiong et al., Expert Opin Emerg Drugs 14:67-84, 2009; Johnson et al., Handb Clin Neurol 127:115-128, 2015; Dixon et al., J Neurotrauma 5:91-104, 1988)). The closed-head, impact-acceleration model of TBI designed by Marmarou et al., 1994 (J Neurosurg 80:291-300, 1994), when used to produce mild to moderate TBI, produces diffuse axonal injuries without significant additional focal injuries of the

  14. A kinematic model for 3-D head-free gaze-shifts

    PubMed Central

    Daemi, Mehdi; Crawford, J. Douglas

    2015-01-01

    Rotations of the line of sight are mainly implemented by coordinated motion of the eyes and head. Here, we propose a model for the kinematics of three-dimensional (3-D) head-unrestrained gaze-shifts. The model was designed to account for major principles in the known behavior, such as gaze accuracy, spatiotemporal coordination of saccades with vestibulo-ocular reflex (VOR), relative eye and head contributions, the non-commutativity of rotations, and Listing's and Fick constraints for the eyes and head, respectively. The internal design of the model was inspired by known and hypothesized elements of gaze control physiology. Inputs included retinocentric location of the visual target and internal representations of initial 3-D eye and head orientation, whereas outputs were 3-D displacements of eye relative to the head and head relative to shoulder. Internal transformations decomposed the 2-D gaze command into 3-D eye and head commands with the use of three coordinated circuits: (1) a saccade generator, (2) a head rotation generator, (3) a VOR predictor. Simulations illustrate that the model can implement: (1) the correct 3-D reference frame transformations to generate accurate gaze shifts (despite variability in other parameters), (2) the experimentally verified constraints on static eye and head orientations during fixation, and (3) the experimentally observed 3-D trajectories of eye and head motion during gaze-shifts. We then use this model to simulate how 2-D eye-head coordination strategies interact with 3-D constraints to influence 3-D orientations of the eye-in-space, and the implications of this for spatial vision. PMID:26113816

  15. Bisphosphonates and osteonecrosis of the jaw.

    PubMed

    Sambrook, Philip; Olver, Ian; Goss, Alastair

    2006-10-01

    Recently an association between bisphosphonate use and a rare dental condition termed 'osteonecrosis of the jaw' (ONJ) has been reported. Patients with osteoporosis and Paget disease who take bisphosphonates have a significantly reduced risk of fracture and other skeletal complications. This represents significant health benefits, against which the small risk of ONJ needs to be considered. In patients with bone malignancy, the risk of ONJ needs to be balanced against the benefit of therapy on the underlying malignancy. There are still many uncertainties about this condition. This position paper seeks to summarise what is currently known about ONJ to provide information to medical practitioners and dental practitioners.

  16. Osteonecrosis caused by Bisphosphonates: a clinical case

    PubMed Central

    SPINELLI, D.; DE VICO, G.; BONINO, M.; BARLATTANI, A.; BOLLERO, P.; BARLATTANI, A.

    2010-01-01

    SUMMARY The osteonecrosis of the maxillares caused by bisphosphonates (OMB) either wrongly known or not reconised in earlier times became nowadays very important among the dentists and maxillo-facials surgeons because of the potential serious consequences that might bring in the oral cave of the patients, who are suffering already for their base condition. The goal of our work was to verify if a deep treatment and an attentive observation with a close follow-up can bring to the resolution of serious cases of ostenecrosis of the maxillares by bisphosphonantes. Although without a statistic value our case report put the basis for a chance to execute wider casistic studies. PMID:23285372

  17. Spontaneous osteonecrosis of navicular and talus (SONNT).

    PubMed

    Vaishya, Raju; Kumar, Virender; Agarwal, Amit Kumar; Vijay, Vipul

    2016-01-01

    We describe a rare case of simultaneous and spontaneous osteonecrosis affecting bilateral navicular and talar bones in a young male. On both sides, there was associated symptomatic talonavicular and naviculocuneiform arthritis. The more symptomatic left foot was managed successfully by talonavicular-cuneiform (TNC) arthrodesis and core decompression of talar body. A probable cause of this rare disorder was most likely due to a developmental anomaly in the preaxial ray of the foot. As no literature is currently available for this rare condition, our case report is intended to provide a referral point for future studies in the early diagnosis and management of this condition.

  18. Head and cervical spine posture in behaving rats: implications for modeling human conditions involving the head and cervical spine.

    PubMed

    Griffin, C; Choong, W Y; Teh, W; Buxton, A J; Bolton, P S

    2015-02-01

    The aim of this study was to define the temporal and spatial (postural) characteristics of the head and cervical vertebral column (spine) of behaving rats in order to better understand their suitability as a model to study human conditions involving the head and neck. Time spent in each of four behavioral postures was determined from video tape recordings of rats (n = 10) in the absence and presence of an intruder rat. Plain film radiographic examination of a subset of these rats (n = 5) in each of these postures allowed measurement of head and cervical vertebral column positions adopted by the rats. When single they were quadruped or crouched most (∼80%) of the time and bipedal either supported or free standing for only ∼10% of the time. The introduction of an intruder significantly (P < 0.0001) reduced the proportion of time rats spent quadruped (median, from 71% to 47%) and bipedal free standing (median, from 2.9% to 0.4%). The cervical spine was orientated (median, 25-75 percentile) near vertical (18.8°, 4.2°-30.9°) when quadruped, crouched (15.4°, 7.6°-69.3°) and bipedal supported (10.5°, 4.8°-22.6°) but tended to be less vertical oriented when bipedal free standing (25.9°, 7.7°-39.3°). The range of head positions relative to the cervical spine was largest when crouched (73.4°) and smallest when erect free standing (17.7°). This study indicates that, like humans, rats have near vertical orientated cervical vertebral columns but, in contrast to humans, they displace their head in space by movements at both the cervico-thoracic junction and the cranio-cervical regions.

  19. Underbody Blast Models of TBI Caused by Hyper-Acceleration and Secondary Head Impact

    DTIC Science & Technology

    2016-02-01

    describes engineering advancements made to the PCI injury model including helmet material testing, projectile impact energy /head kinematics and impact...mold to maximize the contact area and thus the load distribution on the rat head during impact. The effective transfer of energy onto the head...60 were fully conscious. Explosion within the water ensured a non-compressible transfer of the explosive energy onto the bottom of the lower platform

  20. Thrust and torque characteristics based on a new cutter-head load model

    NASA Astrophysics Data System (ADS)

    Liu, Jianqin; Ren, Jiabao; Guo, Wei

    2015-07-01

    Full face rock tunnel boring machine(TBM) has been widely used in hard rock tunnels, however, there are few published theory about cutter-head design, and the design criteria of cutter-head under complex geological is not clear yet. To deal with the complex relationship among geological parameters, cutter parameters, and operating parameters during tunneling processes, a cutter-head load model is established by using CSM(Colorado school of mines) prediction model. Force distribution on cutter-head under a certain geology is calculated with the new established load model, and result shows that inner cutters bear more force than outer cutters, combining with disc cutters abrasion; a general principle of disc cutters' layout design is proposed. Within the model, the relationship among rock uniaxial compressive strength(UCS), penetration and thrust on cutter-head are analyzed, and the results shows that with increasing penetration, cutter thrust increases, but the growth rate slows and higher penetration makes lower special energy(SE). Finally, a fitting mathematical model of ZT(ratio of cutter-head torque and thrust) and penetration is established, and verified by TB880E, which can be used to direct how to set thrust and torque on cutter-head. When penetration is small, the cutter-head thrust is the main limiting factor in tunneling; when the penetration is large, cutter-head torque is the major limiting factor in tunneling. Based on the new cutter-head load model, thrust and torque characteristics of TBM further are researched and a new way for cutter-head layout design and TBM tunneling operations is proposed.

  1. Combined with Bone Marrow-Derived Cells and rhBMP-2 for Osteonecrosis after Femoral Neck Fractures in Children and Adolescents: A case series

    PubMed Central

    Gao, Fuqiang; Sun, Wei; Guo, Wanshou; Wang, Bailiang; Cheng, Liming; Li, Zirong

    2016-01-01

    Osteonecrosis of the femoral head (ONFH) following femoral neck fractures is a rare, yet severe, disorder in children and adolescents. This study evaluated the effectiveness of core decompression (CD) combined with implantation of bone marrow–derived cells (BMDC) and rhBMP-2 for osteonecrosis of femoral head (ONFH) after femoral neck fractures in children and adolescents. This study included 51 patients, aged 11.4–18.1 years, with ARCO stages I–III ONFH after femoral neck fractures between 2004 and 2010. The hips were divided into two groups based on whether the lateral pillar of the femoral head (LPFH) was preserved: LPFH and non-LPFH groups. All patients were followed up clinically and radiographically for a minimum of 5 years. 44 patients (86.3%) had improved clinical outcome. Radiologically, 9 of the 51 hips (17.6%) exhibited collapse onset or progression of the femoral head or narrowing of the hip joint space, and one patient in the non-LPFH group required hip arthroplasty due to the worsened syndrome. The technique provided an effective therapeutic option for children and adolescents with ONFH following femoral neck fractures. It relieves hip pain and prevents the progression of osteonecrosis in young patients lasting more than 5 years after surgery. PMID:27477836

  2. Environmental Anchoring of Head Direction in a Computational Model of Retrosplenial Cortex

    PubMed Central

    2016-01-01

    Allocentric (world-centered) spatial codes driven by path integration accumulate error unless reset by environmental sensory inputs that are necessarily egocentric (body-centered). Previous models of the head direction system avoided the necessary transformation between egocentric and allocentric reference frames by placing visual cues at infinity. Here we present a model of head direction coding that copes with exclusively proximal cues by making use of a conjunctive representation of head direction and location in retrosplenial cortex. Egocentric landmark bearing of proximal cues, which changes with location, is mapped onto this retrosplenial representation. The model avoids distortions due to parallax, which occur in simple models when a single proximal cue card is used, and can also accommodate multiple cues, suggesting how it can generalize to arbitrary sensory environments. It provides a functional account of the anatomical distribution of head direction cells along Papez' circuit, of place-by-direction coding in retrosplenial cortex, the anatomical connection from the anterior thalamic nuclei to retrosplenial cortex, and the involvement of retrosplenial cortex in navigation. In addition to parallax correction, the same mechanism allows for continuity of head direction coding between connected environments, and shows how a head direction representation can be stabilized by a single within arena cue. We also make predictions for drift during exploration of a new environment, the effects of hippocampal lesions on retrosplenial cells, and on head direction coding in differently shaped environments. SIGNIFICANCE STATEMENT The activity of head direction cells signals the direction of an animal's head relative to landmarks in the world. Although driven by internal estimates of head movements, head direction cells must be kept aligned to the external world by sensory inputs, which arrive in the reference frame of the sensory receptors. We present a computational

  3. Effects of head models and dipole source parameters on EEG fields.

    PubMed

    Peng, Li; Peng, Mingming; Xu, Anhuai

    2015-01-01

    Head model and an efficient method for computing the forward EEG (electroencephalography)problem are essential to dipole source localization(DSL). In this paper, we use less expensive ovoid geometry to approximate human head, aiming at investigating the effects of head shape and dipole source parameters on EEG fields. The application of point least squares (PLS) based on meshless method was introduced for solving EEG forward problem and numerical simulation is implemented in three kinds of ovoid head models. We present the performances of the surface potential in the face of varying dipole source parameters in detail. The results show that the potential patterns are similar for different dipole position in different head shapes, but the peak value of potential is significantly influenced by the head shape. Dipole position induces a great effect on the peak value of potential and shift of peak potential. The degree of variation between sphere head model and non-sphere head models is seen at the same time. We also show that PLS method with the trigonometric basis is superior to the constant basis, linear basis, and quadratic basis functions in accuracy and efficiency.

  4. Effects of Head Models and Dipole Source Parameters on EEG Fields

    PubMed Central

    Peng, Li; Peng, Mingming; Xu, Anhuai

    2015-01-01

    Head model and an efficient method for computing the forward EEG (electroencephalography)problem are essential to dipole source localization(DSL). In this paper, we use less expensive ovoid geometry to approximate human head, aiming at investigating the effects of head shape and dipole source parameters on EEG fields. The application of point least squares (PLS) based on meshless method was introduced for solving EEG forward problem and numerical simulation is implemented in three kinds of ovoid head models. We present the performances of the surface potential in the face of varying dipole source parameters in detail. The results show that the potential patterns are similar for different dipole position in different head shapes, but the peak value of potential is significantly influenced by the head shape. Dipole position induces a great effect on the peak value of potential and shift of peak potential. The degree of variation between sphere head model and non-sphere head models is seen at the same time. We also show that PLS method with the trigonometric basis is superior to the constant basis, linear basis, and quadratic basis functions in accuracy and efficiency. PMID:25893011

  5. A Success Story: The Evaluation of Four Head Start Bilingual Multicultural Curriculum Models.

    ERIC Educational Resources Information Center

    Arenas, Soledad; Trujillo, Lorenzo A.

    An evaluation was made of four Head Start bilingual/ multicultural curriculum models to assess their effectiveness and impact on children, staff, and parents. Intended as a pre-post design (with 90 children at each of eight Head Start replication sites and with treatment and control groups stratified on the basis of Spanish or English language…

  6. Constructing three-dimensional detachable and composable computer models of the head and neck.

    PubMed

    Fan, Min; Dai, Peishan; Zheng, Buhong; Li, Xinchun

    2015-06-01

    The head and neck region has a complex spatial and topological structure, three-dimensional (3D) computer model of the region can be used in anatomical education, radiotherapy planning and surgical training. However, most of the current models only consist of a few parts of the head and neck, and the 3D models are not detachable and composable. In this study, a high-resolution 3D detachable and composable model of the head and neck was constructed based on computed tomography (CT) serial images. First, fine CT serial images of the head and neck were obtained. Then, a color lookup table was created for 58 structures, which was used to create anatomical atlases of the head and neck. Then, surface and volume rendering methods were used to reconstruct 3D models of the head and neck. Smoothing and polygon reduction steps were added to improve 3D rendering effects. 3D computer models of the head and neck, including the sinus, pharynx, vasculature, nervous system, endocrine system and glands, muscles, bones and skin, were reconstructed. The models consisted of 58 anatomical detachable and composable structures and each structure can be displayed individually or together with other structures.

  7. BISPHOSPHONATE-INDUCED MAXILLOFACIAL OSTEONECROSIS IN OSTEOPOROTIC INDIVIDUALS

    PubMed Central

    da Silva Santos, Paulo Sérgio; Oliveira, Márcio Augusto; Felix, Valtuir Barbosa

    2015-01-01

    Bisphosphonate-related osteonecrosis of the maxillae may be an important complication of long-term osteoporosis treatment. The possibility of osteonecrosis of the maxillae in patients exposed to nitrogenated bisphosphonates was first described in 2003. Since then, case reports and retrospective studies have demonstrated higher percentages of occurrence of osteonecrosis in patients who have used or are using bisphosphonates. Although this complication may be spontaneous, invasive oral procedures have a role as risk factors associated with dental procedures such as tooth extractions and other bone operations. In addition, tooth infections and periodontal disease have been reported to be the main risk factors for development of bisphosphonate-induced osteonecrosis of the maxillae. For this reason, dentists, general clinicians, orthopedists, geriatricians and oral-maxillofacial surgeons need to be aware of this problem and work in a multidisciplinary environment, thereby stimulating early diagnosis and prevention of further potential cases. PMID:27027044

  8. Total hip arthroplasty in steroid-induced osteonecrosis: early functional and radiological outcomes

    PubMed Central

    Rahman, Wael A.; Garbuz, Donald S.; Masri, Bassam A.

    2013-01-01

    Background The proportion of total hip arthroplasties (THAs) associated with corticosteroid use is uncertain, and the mechanisms of corticosteroid-induced osteonecrosis remain unknown. We sought to evaluate the clinical and radiographic outcomes, complications and satisfaction with THA among patients with corticosteroid-induced osteonecrosis. Methods We retrospectively assessed functional outcome at a minimum 1-year follow-up using the Western Ontario and MacMaster Universities Arthritis Index (WOMAC); Oxford Hip Score; Short Form (SF)-12; University of California, Los Angeles (UCLA) Activity; and patient satisfaction scores. Results We included 31 patients (35 hips). The average follow-up was 20 (range 12–55) months, and the average age at surgery was 47 (range 19–78) years. At follow-up, patients showed significant improvement in all 4 components of the WOMAC (means: function 84, stiffness 75, pain 86, global 84), Oxford-12 (mean 83) and SF-12 (means: mental 40 and physical 48) scores. However, there was no significant improvement in the UCLA Activity scores. Mean patient satisfaction scores were good for pain relief (86), function (80), recreation (77.5) and overall results of surgery (86). Radiographic review at follow-up showed that all components were well fixed with no evidence of loosening. The complication rate was high (17%), with 6 complications in 5 patients (6 of 35 hips). Four patients (4 of 35 hips; 11%) required reoperations. Conclusion Total hip arthroplasty in patients with corticosteroid-induced osteonecrosis of the femoral head is successful in reducing pain and improving function; however, the rate of complications and reoperation is high. PMID:22992403

  9. Testosterone Therapy Can Interact With Thrombophilia, Leading to Osteonecrosis.

    PubMed

    Glueck, Charles J; Riaz, Rashid; Prince, Marloe; Freiberg, Richard A; Wang, Ping

    2015-12-01

    Although this effect is not widely recognized, testosterone therapy can interact with thrombophilia, causing osteonecrosis. In 12 men and 4 women who had idiopathic osteonecrosis a median of 6 months after the onset of testosterone therapy, the authors examined the interaction between testosterone therapy and previously undiagnosed thrombophilia. The authors hypothesized that patients who had osteonecrosis after starting testosterone therapy were more likely than 110 normal control subjects or 48 patients who had osteonecrosis and were not receiving testosterone therapy to have thrombophilia. Measures of thrombophilia included Factor V Leiden, prothrombin, PAI-1 gene mutations, Factor VIII, Factor XI, anticardiolipin antibody immunoglobulin G or immunoglobulin M, and homocysteine values. In 10 cases, osteonecrosis occurred 6 months or less after the onset of testosterone therapy, and in all 16 cases, it occurred after a median of 6 months of testosterone therapy. Of the 16 cases, 5 (31%) were Factor V Leiden heterozygotes vs 2 of 109 (2%) healthy control subjects (P=.0003) and 4 of 48 patients who had osteonecrosis and were not receiving testosterone therapy (P=.04). Of the 16 cases, 4 (25%) had high (>150%) Factor VIII levels vs 7 of 103 (7%) healthy control subjects (P=.04), and 3 (19%) had high (>150%) Factor XI levels vs 3 of 101 (3%) healthy control subjects (P=.03). Of the 16 patients with osteonecrosis, 14 (88%) had at least 1 abnormal procoagulant value (of the 8 measured) vs 47 of 110 (43%) healthy control subjects (P=.0009). Of the 5 men whose serum estradiol level was measured while they were receiving testosterone therapy, this level was high (≥42.6 pg/mL) in 4. When testosterone therapy is given to patients with thrombophilia, they are at increased risk for osteonecrosis.

  10. Osteoarthritis-like disorder in rats with vascular deprivation-induced necrosis of the femoral head.

    PubMed

    Levin, D; Norman, D; Zinman, C; Misselevich, I; Reis, D N; Boss, J H

    1999-01-01

    The reparative processes following vascular deprivation-induced necrosis of the femoral head were studied histologically in rats sacrificed 2, 7, 14, 21, 42 and 92 days postoperatively. The blood supply was severed by incision of the periosteum at the neck of the femoral head and transection of the ligamentum teres. Granulation tissue and a well-vascularized fibrous tissue originating from the joint capsule invaded the necrotic marrow spaces. With progressive resorption of the necrotic tissues and osteoneogenesis, both appositional and intramembranous, within the fibrotic intertrabecular spaces, the remodeling process led to a shift of the normal spongy architecture of the femoral head to a compacta-like one. In a few cases, osseous bridges bisected a necrotic physeal cartilage at the latest time intervals. The remodeling was associated with flattening of the femoral heads as well as with degenerative, regenerative and reparative alterations of the articular cartilage. In one of the two femoral heads obtained three months postoperatively, cystic spaces developed in the fibrous subchondral zone. Our findings are consistent with the view that ineffective attempts at restoring the prenecrotic state of the femoral head by replacing the necrotic with viable tissue triggers the collapse of the femoral head. Thickening and condensation of the subchondral bone, leading to increased stiffness of the subchondral zone, result in the osteoarthritis-like disorder. Mimicking the well-known phases of human osteonecrosis, the model readily allows for preclinical studies of therapeutic regimens.

  11. Modeling length-tension properties of RCPm muscles during voluntary retraction of the head.

    PubMed

    Hallgren, Richard C

    2014-08-01

    Head retraction exercises are one of several commonly used clinical tools that are used to assess and treat patients with head and neck pain and to aid in restoration of a normal neutral head posture. Retraction of the head results in flexion of the occipitoatlantal (OA) joint and stretching of rectus capitis posterior minor (RCPm) muscles. The role that retraction of the head might have in treating head and neck pain patients is currently unknown. RCPm muscles arise from the posterior tubercle of the posterior arch of C1 and insert into the occipital bone inferior to the inferior nuchal line and lateral to the midline. RCPm muscles are the only muscles that attach to the posterior arch of C1. The functional role of RCPm muscles has not been clearly defined. The goal of this project was to develop a three-dimensional, computer-based biomechanical model of the posterior aspect of the OA joint. This model should help clarify why voluntary head retraction exercises seem to contribute to the resolution of head and neck pain and restoration of a normal head posture in some patients. The model documents that length-tension properties of RCPm muscles are significantly affected by variations in the physical properties of the musculotendonous unit. The model suggests that variations in the cross sectional area of RCPm muscles due to pathologies that weaken the muscle, such as muscle atrophy, may reduce the ability of these muscles to generate levels of force that are necessary for the performance of normal, daily activities. The model suggests that the main benefit of the initial phase of head retraction exercises may be to strengthen RCPm muscles through eccentric contractions, and that the main benefit of the final phase of retraction may be to stretch the muscles as the final position is held.

  12. Head out of water immersion: A simulation model of microgravity?

    NASA Astrophysics Data System (ADS)

    Verheyden, B.; Beckers, F.; Aubert, Ae.

    Introduction. It is well known that during weightlessness a redistribution of body fluids occurs towards the upper parts of the body causing altered cardiovascular reflex activities. During head out of water immersion (HOI), the hydrostatic pressure on the soft tissues of the lower limbs causes thoracic blood volume to increase, comparably with the observed haemodynamics during weightlessness. The purpose of this study was to evaluate HOI as a simulation model of microgravity concerning the cardiovascular autonomic control system. Methods. Heartbeat and continuous blood pressure (fingerplethysmography) were measured in 18 (age=22.2± 10.3yr) healthy subjects in different conditions: Supine, sitting and standing in air (25C); upright submersion in thermo neutral water (34C) up to the shoulders (HOI). After 5 minutes of accommodation to the position and condition, recordings were made for 10 minutes. Time domain parameters (MeanRR, SD, rMSSD and pNN50) as well as frequency domain parameters (Total Power, high frequency (HF), low frequency (LF)) of HRV and BPV were calculated. An index of baroreflex sensitivity was determined by the sequence method. Results from the HOI experiment were compared to results obtained from microgravity phases in parabolic flights in 5 subjects. Results. Cardiac autonomic control during HOI was characterized by a gain in vagal predominance as shown by a decrease of the LF/HF-ratio from 950 ± 130 ms2 during standing control towards 389 ± 119 ms2 during HOI and a increase of BRS by approximately 20%. As a result, heart rate decreased by approximately 28% during HOI. The same evolution was shown during the transition from a standing control position towards 0G obtained during parabolic flights. LF power of BPV, as a marker of peripheral vasomotor sympathetic activity, decreased significantly both in absolute values and normalized units during HOI compared to standing and seated control (p < 0.05). In contrast, an increase in LF power of BPV

  13. Modeling and Vibration Analysis of Spinning Hard Disk and Head Assembly

    NASA Astrophysics Data System (ADS)

    Lin, Kao-An; Huang, Shyh-Chin

    A read/write head assembly attached to a spinning disk was modeled and investigated through a different approach, in which the head assembly was represented by a suspension arm with an attached mass and an air spring (film) at its free end. The receptance method was applied to connect the spinning disk and the head assembly. The natural frequencies and mode shapes of the combined spinning disk-fixed head assembly as a whole were then interpreted. Numerical results showed that the head assembly induced extra modes from a single disk. Even for just weak coupling between disk and head, the bifurcations of mode shapes were very obvious, but the changes of natural frequencies were slight. The effects on frequency changes due to head's flexibility, air spring constant, head's location, and spinning speed were examined as well. Disk's spinning speed was found to pull the disk-head frequency loci to pass through the crossings of single disk's frequency loci and induce curve veering phenomenon.

  14. Development/global validation of a 6-month-old pediatric head finite element model and application in investigation of drop-induced infant head injury.

    PubMed

    Li, Zhigang; Luo, Xiao; Zhang, Jinhuan

    2013-12-01

    Drop is a frequent cause for infant head injury. To date, finite element (FE) modeling was gradually used to investigate child head dynamic response under drop impact conditions, however, two shortages still exist on this topic: (1) due to ethical reasons, none of developed 6-month-old (6MO) head FE model was found to be quantitatively validated against child cadaver tests at similar age group; (2) drop height and impact surface stiffness effects on infant head responses were not comprehensively investigated. In this study, motivated by the recently published material properties of soft tissues (skull and suture, etc.) and reported pediatric head global cadaver tests, a 6MO child head FE model was developed and simulated results compared with the child cadaver experimental data under compression and drop conditions. Comparison of results indicated that the FE model showed a fairly good biofidelic behavior in most dynamic responses. The validated FE model was further used to investigate effects of different drop heights and impact surface stiffness on the head dynamic responses. Numerical results show that the pediatric head mechanical parameters (peak acceleration, HIC, maximal vonMises stress and maximal first principal strain of skull) keep increasing with the increase in drop height, and exhibit "logarithmic function" shapes at "fast-slow" trends with increase in impact surface stiffness. Based on above analysis, the regressions were conducted to describe the relationship between drop height and impact surface stiffness and head global injury predictors (head peak acceleration, HIC, etc.). This paper provides a fundamental study of child head injury mechanism and protection under drop conditions.

  15. Development, Validation and Parametric study of a 3-Year-Old Child Head Finite Element Model

    NASA Astrophysics Data System (ADS)

    Cui, Shihai; Chen, Yue; Li, Haiyan; Ruan, ShiJie

    2015-12-01

    Traumatic brain injury caused by drop and traffic accidents is an important reason for children's death and disability. Recently, the computer finite element (FE) head model has been developed to investigate brain injury mechanism and biomechanical responses. Based on CT data of a healthy 3-year-old child head, the FE head model with detailed anatomical structure was developed. The deep brain structures such as white matter, gray matter, cerebral ventricle, hippocampus, were firstly created in this FE model. The FE model was validated by comparing the simulation results with that of cadaver experiments based on reconstructing the child and adult cadaver experiments. In addition, the effects of skull stiffness on the child head dynamic responses were further investigated. All the simulation results confirmed the good biofidelity of the FE model.

  16. Influence of head mass on temporo-parietal skull impact using finite element modeling.

    PubMed

    Sahoo, Debasis; Deck, Caroline; Yoganandan, Narayan; Willinger, Rémy

    2015-09-01

    The effect of head mass on its biomechanical response during lateral impact to the head is investigated in this computational study. The mass of the head of a state-of-the-art validated finite element head model is altered by ± 10 % from the base value of 4.7 kg. Numerical simulations of lateral head impacts for 30 cases (representing 15 human cadaver experiments × 2 mass configurations) are performed using the LS-DYNA solver at different velocities ranging from 2.4 to 6.5 m/s and three impacting conditions representing different stiffness and shapes of the contact/impact surfaces. Results are compared with the original model using the baseline head mass, thus resulting in a total of 45 simulations. Present findings show that the head mass has greater influence for peak interaction forces and the force has a greater dependency on stiffness of contact surface than the shape. Mass variations have also influence on skull strain energy. Regardless of increase/decrease in skull strain energy influenced by head mass variations used in the computational study, the 50 % fracture tolerance limit was unaltered, which was 544 mJ. The present study gives a better understanding of the mechanism of temporo-parietal skull impact.

  17. A Head in Virtual Reality: Development of A Dynamic Head and Neck Model

    ERIC Educational Resources Information Center

    Nguyen, Ngan; Wilson, Timothy D.

    2009-01-01

    Advances in computer and interface technologies have made it possible to create three-dimensional (3D) computerized models of anatomical structures for visualization, manipulation, and interaction in a virtual 3D environment. In the past few decades, a multitude of digital models have been developed to facilitate complex spatial learning of the…

  18. Osteonecrosis in patients with malignant lymphoma. A review of 31 cases

    SciTech Connect

    Rossleigh, M.A.; Smith, J.; Straus, D.J.; Engel, I.A.

    1986-09-01

    Osteonecrosis of the femoral and humeral heads is a serious complication of therapy for Hodgkin's disease and non-Hodgkin's lymphoma. Twenty-five patients were reassessed 5 years after being initially reported, in order to study the further progress and natural history of this complication. In addition, six recent patients who have also developed this condition are presented. With 5-year additional follow-up, no patient had developed symptoms of osteonecrosis in any bone other than those initially involved. Five patients developed severe complications thought to arise from their therapy suggesting that this group of patients were more sensitive to radiation injury than other patients treated with this modality. During the relatively short follow-up 5-year period, a surprising finding was the fact that 31% of the patients with Hodgkin's disease and 50% with non-Hodgkin's lymphoma had died. It is recommended that patients treated for lymphoma with steroid containing chemotherapy and radiotherapy be observed carefully for the occurrence of joint pain. Early diagnosis should lead to attempts to prevent total joint destruction.

  19. Double-ring network model of the head-direction system

    NASA Astrophysics Data System (ADS)

    Xie, Xiaohui; Hahnloser, Richard H.; Seung, H. Sebastian

    2002-10-01

    In the head-direction system, the orientation of an animal's head in space is encoded internally by persistent activities of a pool of cells whose firing rates are tuned to the animal's directional heading. To maintain an accurate representation of the heading information when the animal moves, the system integrates horizontal angular head-velocity signals from the vestibular nuclei and updates the representation of directional heading. The integration is a difficult process, given that head velocities can vary over a large range and the neural system is highly nonlinear. Previous models of integration have relied on biologically unrealistic mechanisms, such as instantaneous changes in synaptic strength, or very fast synaptic dynamics. In this paper, we propose a different integration model with two populations of neurons, which performs integration based on the differential input of the vestibular nuclei to these two populations. We mathematically analyze the dynamics of the model and demonstrate that with carefully tuned synaptic connections it can accurately integrate a large range of the vestibular input, with potentially slow synapses.

  20. Principle Study of Head Meridian Acupoint Massage to Stress Release via Grey Data Model Analysis

    PubMed Central

    Lee, Ya-Ting

    2016-01-01

    This paper presents the scientific study of the effectiveness and action principle of head meridian acupoint massage by applying the grey data model analysis approach. First, the head massage procedure for massaging the important head meridian acupuncture points including Taiyang, Fengfu, Tianzhu, Fengqi, and Jianjing is formulated in a standard manner. Second, the status of the autonomic nervous system of each subject is evaluated by using the heart rate variability analyzer before and after the head massage following four weeks. Afterward, the physiological factors of autonomic nerves are quantitatively analyzed by using the grey data modeling theory. The grey data analysis can point out that the status of autonomic nervous system is greatly improved after the massage. The order change of the grey relationship weighting of physiological factors shows the action principle of the sympathetic and parasympathetic nerves when performing head massage. In other words, the grey data model is able to distinguish the detailed interaction of the autonomic nervous system and the head meridian acupoint massage. Thus, the stress relaxing effect of massaging head meridian acupoints is proved, which is lacked in literature. The results can be a reference principle for massage health care in practice. PMID:26904144

  1. Principle Study of Head Meridian Acupoint Massage to Stress Release via Grey Data Model Analysis.

    PubMed

    Lee, Ya-Ting

    2016-01-01

    This paper presents the scientific study of the effectiveness and action principle of head meridian acupoint massage by applying the grey data model analysis approach. First, the head massage procedure for massaging the important head meridian acupuncture points including Taiyang, Fengfu, Tianzhu, Fengqi, and Jianjing is formulated in a standard manner. Second, the status of the autonomic nervous system of each subject is evaluated by using the heart rate variability analyzer before and after the head massage following four weeks. Afterward, the physiological factors of autonomic nerves are quantitatively analyzed by using the grey data modeling theory. The grey data analysis can point out that the status of autonomic nervous system is greatly improved after the massage. The order change of the grey relationship weighting of physiological factors shows the action principle of the sympathetic and parasympathetic nerves when performing head massage. In other words, the grey data model is able to distinguish the detailed interaction of the autonomic nervous system and the head meridian acupoint massage. Thus, the stress relaxing effect of massaging head meridian acupoints is proved, which is lacked in literature. The results can be a reference principle for massage health care in practice.

  2. Augmented saliency model using automatic 3D head pose detection and learned gaze following in natural scenes.

    PubMed

    Parks, Daniel; Borji, Ali; Itti, Laurent

    2015-11-01

    Previous studies have shown that gaze direction of actors in a scene influences eye movements of passive observers during free-viewing (Castelhano, Wieth, & Henderson, 2007; Borji, Parks, & Itti, 2014). However, no computational model has been proposed to combine bottom-up saliency with actor's head pose and gaze direction for predicting where observers look. Here, we first learn probability maps that predict fixations leaving head regions (gaze following fixations), as well as fixations on head regions (head fixations), both dependent on the actor's head size and pose angle. We then learn a combination of gaze following, head region, and bottom-up saliency maps with a Markov chain composed of head region and non-head region states. This simple structure allows us to inspect the model and make comments about the nature of eye movements originating from heads as opposed to other regions. Here, we assume perfect knowledge of actor head pose direction (from an oracle). The combined model, which we call the Dynamic Weighting of Cues model (DWOC), explains observers' fixations significantly better than each of the constituent components. Finally, in a fully automatic combined model, we replace the oracle head pose direction data with detections from a computer vision model of head pose. Using these (imperfect) automated detections, we again find that the combined model significantly outperforms its individual components. Our work extends the engineering and scientific applications of saliency models and helps better understand mechanisms of visual attention.

  3. Feasibility and Efficacy of Autologous Bone Marrow Aspirate Transplantation Combined with Human Parathyroid Hormone 1-34 Administration to Treat Osteonecrosis in a Rabbit Model

    PubMed Central

    Sugaya, Hisashi; Aoto, Katsuya; Uemura, Kenta; Tanaka, Kenta; Akaogi, Hiroshi; Yamazaki, Masashi; Mishima, Hajime

    2017-01-01

    No studies have examined the transplantation of a bone marrow aspirate (BMA) containing mesenchymal stem cells (MSCs) combined with human parathyroid hormone 1-34 (hPTH1-34) administration. Therefore, we evaluated the feasibility and efficacy of autologous BMA transplantation combined with hPHT1-34 administration in a bone necrosis model. The metatarsal bones of rabbits were necrotized using liquid nitrogen, and the rabbits received a BMA transplantation or saline injection followed by hPTH1-34 (30 μg/kg) or saline administration three times per week (n = 3-4 per group). The rabbits were euthanized at 12 weeks after the initiation of treatment. No systemic adverse effects or local neoplastic lesions were observed. Importantly, the rabbits in the BMA transplantation plus hPTH1-34 group showed the highest bone volumes and histological scores of new bone. These data confirmed the feasibility of BMA transplantation combined with hPTH1-34, at least during the experimental period. The observed efficacy may be explained by a synergistic effect from the stimulation of MSC differentiation to osteoblasts with hPTH1-34-mediated suppression of apoptosis in osteoblasts. These results indicate the promising potential for BMA transplantation combined with hPTH1-34 administration in bone necrosis treatment. Longer term experiments are needed to confirm the safety of this therapeutic strategy. PMID:28386485

  4. Crowd modeling framework using fast head detection and shape-aware matching

    NASA Astrophysics Data System (ADS)

    Zhou, Tao; Yang, Jie; Loza, Artur; Bhaskar, Harish; Al-Mualla, Mohammed

    2015-03-01

    A framework for crowd modeling using a combination of multiple kernel learning (MKL)-based fast head detection and shape-aware matching is proposed. First, the MKL technique is used to train a classifier for head detection using a combination of the histogram of oriented gradient and local binary patterns feature sets. Further, the head detection process is accelerated by implementing the classification procedure only at those spatial locations in the image where the gradient points overlap with moving objects. Such moving objects are determined using an adaptive background subtraction technique. Finally, the crowd is modeled as a deformable shape through connected boundary points (head detection) and matched with the subsequent detection from the next frame in a shape-aware manner. Experimental results obtained from crowded videos show that the proposed framework, while being characterized by a low computation load, performs better than other state-of-art techniques and results in reliable crowd modeling.

  5. Surgical treatment of jaw osteonecrosis in "Krokodil" drug addicted patients.

    PubMed

    Poghosyan, Yuri M; Hakobyan, Koryun A; Poghosyan, Anna Yu; Avetisyan, Eduard K

    2014-12-01

    Retrospective study of jaw osteonecrosis treatment in patients using the "Krokodil" drug from 2009 to 2013. On the territory of the former USSR countries there is widespread use of a self-produced drug called "Krokodil". Codeine containing analgesics ("Sedalgin", "Pentalgin" etc), red phosphorus (from match boxes) and other easily acquired chemical components are used for synthesis of this drug, which used intravenously. Jaw osteonecrosis develops as a complication in patients who use "Krokodil". The main feature of this disease is jawbone exposure in the oral cavity. Surgery is the main method for the treatment of jaw osteonecrosis in patients using "Krokodil". 40 "Krokodil" drug addict patients with jaw osteonecrosis were treated. Involvement of maxilla was found in 11 patients (27.5%), mandible in 21 (52.5%), both jaws in 8 (20%) patients. 35 Lesions were found in 29 mandibles and 21 lesions in 19 maxillas. Main factors of treatment success are: cessation of "Krokodil" use in the pre- (minimum 1 month) and postoperative period and osteonecrosis area resection of a minimum of 0.5 cm beyond the visible borders of osteonecrosis towards the healthy tissues. Surgery was not delayed until sequestrum formation. In the mandible marginal or segmental resection (with or without TMJ exarticulation) was performed. After surgery recurrence of disease was seen in 8 (23%) cases in the mandible, with no cases of recurrence in the maxilla. According to our experience in this case series, surgery is the main method for the treatment of jaw osteonecrosis in patients using "Krokodil". Cessation of drug use and jaw resection minimize the rate of recurrences in such patients.

  6. Biomechanical studies in an ovine model of non-accidental head injury.

    PubMed

    Anderson, R W G; Sandoz, B; Dutschke, J K; Finnie, J W; Turner, R J; Blumbergs, P C; Manavis, J; Vink, R

    2014-08-22

    This paper presents the head kinematics of a novel ovine model of non-accidental head injury (NAHI) that consists only of a naturalistic oscillating insult. Nine, 7-to-10-day-old anesthetized and ventilated lambs were subjected to manual shaking. Two six-axis motion sensors tracked the position of the head and torso, and a triaxial accelerometer measured head acceleration. Animals experienced 10 episodes of shaking over 30 min, and then remained under anesthesia for 6h until killed by perfusion fixation of the brain. Each shaking episode lasted for 20s resulting in about 40 cycles per episode. Each cycle typically consisted of three impulsive events that corresponded to specific phases of the head's motion; the most substantial of these were interactions typically with the lamb's own torso, and these generated accelerations of 30-70 g. Impulsive loading was not considered severe. Other kinematic parameters recorded included estimates of head power transfer, head-torso flexion, and rate of flexion. Several styles of shaking were also identified across episodes and subjects. Axonal injury, neuronal reaction and albumin extravasation were widely distributed in the hemispheric white matter, brainstem and at the craniocervical junction and to a much greater magnitude in lower body weight lambs that died. This is the first biomechanical description of a large animal model of NAHI in which repetitive naturalistic insults were applied, and that reproduced a spectrum of injury associated with NAHI.

  7. Head-Spine Structure Modeling: Enhancements to Secondary Loading Path Model and Validation of Head-Cervical Spine Model.

    DTIC Science & Technology

    1985-07-01

    Force Contract F33615-80-C-0523. The Air Force project monitor was Dr Eberhardt Privitzer of the Modeling and Analysis Branch, Biodynamics and... contracts , pulling the central tendon downwards and forwards, with little change in the curvature of the diaphragm. The diaphragm pushes down on the abdominal...expiration elastic recoil of the lungs and the tone of the abdominal muscles force the diaphragm upward. Although the diaphragm continues to contract well

  8. Development of head injury assessment reference values based on NASA injury modeling.

    PubMed

    Somers, Jeffrey T; Granderson, Bradley; Melvin, John W; Tabiei, Ala; Lawrence, Charles; Feiveson, Alan; Gernhardt, Michael; Ploutz-Snyder, Robert; Patalak, John

    2011-11-01

    NASA is developing a new crewed vehicle and desires a lower risk of injury compared to automotive or commercial aviation. Through an agreement with the National Association of Stock Car Auto Racing, Inc. (NASCAR®), an analysis of NASCAR impacts was performed to develop new injury assessment reference values (IARV) that may be more relevant to NASA's context of vehicle landing operations. Head IARVs associated with race car impacts were investigated by analyzing all NASCAR recorded impact data for the 2002-2008 race seasons. From the 4015 impact files, 274 impacts were selected for numerical simulation using a custom NASCAR restraint system and Hybrid III 50th percentile male Finite Element Model (FEM) in LS-DYNA. Head injury occurred in 27 of the 274 selected impacts, and all of the head injuries were mild concussions with or without brief loss of consciousness. The 247 noninjury impacts selected were representative of the range of crash dynamics present in the total set of impacts. The probability of head injury was estimated for each metric using an ordered probit regression analysis. Four metrics had good correlation with the head injury data: head resultant acceleration, head change in velocity, HIC 15, and HIC 36. For a 5% risk of AIS≥1/AIS≥2 head injuries, the following IARVs were found: 121.3/133.2 G (head resultant acceleration), 20.3/22.0 m/s (head change in velocity), 1,156/1,347 (HIC 15), and 1,152/1,342 (HIC 36) respectively. Based on the results of this study, further analysis of additional datasets is recommended before applying these results to future NASA vehicles.

  9. 3D dynamic computer model of the head-neck complex.

    PubMed

    Sierra, Daniel A; Enderle, John D

    2006-01-01

    A 3D dynamic computer model for the movement of the head is presented that incorporates anatomically correct information about the diverse elements forming the system. The skeleton is considered as a set of interconnected rigid 3D bodies following the Newton-Euler laws of movement. The muscles are modeled using Enderle's linear model. Finally, the soft tissues, namely the ligaments, intervertebral disks, and zigapophysial joints, are modeled using the finite elements approach. The model is intended to study the neural network that controls movement and maintains the balance of the head-neck complex during eye movements.

  10. A Unified Model of Heading and Path Perception in Primate MSTd

    PubMed Central

    Layton, Oliver W.; Browning, N. Andrew

    2014-01-01

    Self-motion, steering, and obstacle avoidance during navigation in the real world require humans to travel along curved paths. Many perceptual models have been proposed that focus on heading, which specifies the direction of travel along straight paths, but not on path curvature, which humans accurately perceive and is critical to everyday locomotion. In primates, including humans, dorsal medial superior temporal area (MSTd) has been implicated in heading perception. However, the majority of MSTd neurons respond optimally to spiral patterns, rather than to the radial expansion patterns associated with heading. No existing theory of curved path perception explains the neural mechanisms by which humans accurately assess path and no functional role for spiral-tuned cells has yet been proposed. Here we present a computational model that demonstrates how the continuum of observed cells (radial to circular) in MSTd can simultaneously code curvature and heading across the neural population. Curvature is encoded through the spirality of the most active cell, and heading is encoded through the visuotopic location of the center of the most active cell's receptive field. Model curvature and heading errors fit those made by humans. Our model challenges the view that the function of MSTd is heading estimation, based on our analysis we claim that it is primarily concerned with trajectory estimation and the simultaneous representation of both curvature and heading. In our model, temporal dynamics afford time-history in the neural representation of optic flow, which may modulate its structure. This has far-reaching implications for the interpretation of studies that assume that optic flow is, and should be, represented as an instantaneous vector field. Our results suggest that spiral motion patterns that emerge in spatio-temporal optic flow are essential for guiding self-motion along complex trajectories, and that cells in MSTd are specifically tuned to extract complex trajectory

  11. Evaluation of Head Response to Blast Using Sagittal and Transverse Finite Element Head Models

    DTIC Science & Technology

    2012-09-01

    scenario nce in results s and the air layer of nod ration caused b ssue Material priate constitu al parameters yperelastic ma curves at diff s were...viscous material model with bulk properties similar to those of water (Table 2). The viscosity was set to that of water , providing minimal resistance...expected odel predicte ere not include ssue by the nu response in th he brain in th ive parameter imum effectiv in rates did no odel predicte el. at 4 m

  12. Modeling heading and path perception from optic flow in the case of independently moving objects.

    PubMed

    Raudies, Florian; Neumann, Heiko

    2013-01-01

    Humans are usually accurate when estimating heading or path from optic flow, even in the presence of independently moving objects (IMOs) in an otherwise rigid scene. To invoke significant biases in perceived heading, IMOs have to be large and obscure the focus of expansion (FOE) in the image plane, which is the point of approach. For the estimation of path during curvilinear self-motion no significant biases were found in the presence of IMOs. What makes humans robust in their estimation of heading or path using optic flow? We derive analytical models of optic flow for linear and curvilinear self-motion using geometric scene models. Heading biases of a linear least squares method, which builds upon these analytical models, are large, larger than those reported for humans. This motivated us to study segmentation cues that are available from optic flow. We derive models of accretion/deletion, expansion/contraction, acceleration/deceleration, local spatial curvature, and local temporal curvature, to be used as cues to segment an IMO from the background. Integrating these segmentation cues into our method of estimating heading or path now explains human psychophysical data and extends, as well as unifies, previous investigations. Our analysis suggests that various cues available from optic flow help to segment IMOs and, thus, make humans' heading and path perception robust in the presence of such IMOs.

  13. Modeling heading and path perception from optic flow in the case of independently moving objects

    PubMed Central

    Raudies, Florian; Neumann, Heiko

    2013-01-01

    Humans are usually accurate when estimating heading or path from optic flow, even in the presence of independently moving objects (IMOs) in an otherwise rigid scene. To invoke significant biases in perceived heading, IMOs have to be large and obscure the focus of expansion (FOE) in the image plane, which is the point of approach. For the estimation of path during curvilinear self-motion no significant biases were found in the presence of IMOs. What makes humans robust in their estimation of heading or path using optic flow? We derive analytical models of optic flow for linear and curvilinear self-motion using geometric scene models. Heading biases of a linear least squares method, which builds upon these analytical models, are large, larger than those reported for humans. This motivated us to study segmentation cues that are available from optic flow. We derive models of accretion/deletion, expansion/contraction, acceleration/deceleration, local spatial curvature, and local temporal curvature, to be used as cues to segment an IMO from the background. Integrating these segmentation cues into our method of estimating heading or path now explains human psychophysical data and extends, as well as unifies, previous investigations. Our analysis suggests that various cues available from optic flow help to segment IMOs and, thus, make humans' heading and path perception robust in the presence of such IMOs. PMID:23554589

  14. Double-stranded DNA organization in bacteriophage heads: An alternative toroid-based model

    SciTech Connect

    Hud, N.V.

    1995-10-01

    Studies of the organization of double-stranded DNA within bacteriophage heads during the past four decades have produced a wealth of data. However, despite the presentation of numerous models, the true organization of DNA within phage heads remains unresolved. The observations of toroidal DNA structures in electron micrographs of phage lysates have long been cited as support for the organization of DNA in a spool-like fashion. This particular model, like all other models, has not been found to be consistent with all available data. Recently, the authors proposed that DNA within toroidal condensates produced in vitro is organized in a manner significantly different from that suggested by the spool model. This new toroid model has allowed the development of an alternative model for DNA organization within bacteriophage heads that is consistent with a wide range of biophysical data. Here the authors propose that bacteriophage DNA is packaged in a toroid that is folded into a highly compact structure.

  15. Finite-element models of the human head and their applications in forensic practice.

    PubMed

    Raul, Jean-Sébastien; Deck, Caroline; Willinger, Rémy; Ludes, Bertrand

    2008-09-01

    Since the 1960s, predictive human head impact indices have been developed to help the investigation of causation of human head injury. Finite-element models (FEM) can provide interesting tools for the forensic scientists when various human head injury mechanisms need to be evaluated. Human head FEMs are mainly used for car crash evaluations and are not in common use in forensic science. Recent technological progress has resulted in creating more simple tools, which will certainly help to consider the use of FEM in routine forensic practice in the coming years. This paper reviews the main FEMs developed and focuses on the models which can be used as predictive tools. Their possible applications in forensic medicine are discussed.

  16. Experimental Test of Spatial Updating Models for Monkey Eye-Head Gaze Shifts

    PubMed Central

    Van Grootel, Tom J.; Van der Willigen, Robert F.; Van Opstal, A. John

    2012-01-01

    How the brain maintains an accurate and stable representation of visual target locations despite the occurrence of saccadic gaze shifts is a classical problem in oculomotor research. Here we test and dissociate the predictions of different conceptual models for head-unrestrained gaze-localization behavior of macaque monkeys. We adopted the double-step paradigm with rapid eye-head gaze shifts to measure localization accuracy in response to flashed visual stimuli in darkness. We presented the second target flash either before (static), or during (dynamic) the first gaze displacement. In the dynamic case the brief visual flash induced a small retinal streak of up to about 20 deg at an unpredictable moment and retinal location during the eye-head gaze shift, which provides serious challenges for the gaze-control system. However, for both stimulus conditions, monkeys localized the flashed targets with accurate gaze shifts, which rules out several models of visuomotor control. First, these findings exclude the possibility that gaze-shift programming relies on retinal inputs only. Instead, they support the notion that accurate eye-head motor feedback updates the gaze-saccade coordinates. Second, in dynamic trials the visuomotor system cannot rely on the coordinates of the planned first eye-head saccade either, which rules out remapping on the basis of a predictive corollary gaze-displacement signal. Finally, because gaze-related head movements were also goal-directed, requiring continuous access to eye-in-head position, we propose that our results best support a dynamic feedback scheme for spatial updating in which visuomotor control incorporates accurate signals about instantaneous eye- and head positions rather than relative eye- and head displacements. PMID:23118883

  17. Aseptic necrosis of the femoral head after pregnancy: a case report

    PubMed Central

    Nassar, Kawtar; Rachidi, Wafae; Janani, Saadia; Mkinsi, Ouafa

    2016-01-01

    A documented case of beginning aseptic necrosis of the femoral head associated with pregnancy together with a review of the literature about this rare complication of pregnancy is presented. The known risk factors of osteonecrosis are; steroid use, alcoholism, organ transplantation, especially after kidney transplant or bone marrow transplantation bone, systemic lupus erythematosus, dyslipidemia especially hypertriglyceridemia, dysbaric decompression sickness, drepanocytosis and Gaucher's disease. Among the less established factors, we mention procoagulations abnormalities, HIV infection, chemotherapy. We report a case of osteonecrosis of femoral head after pregnancy. PMID:27795792

  18. Changing head model extent affects finite element predictions of transcranial direct current stimulation distributions

    NASA Astrophysics Data System (ADS)

    Indahlastari, Aprinda; Chauhan, Munish; Schwartz, Benjamin; Sadleir, Rosalind J.

    2016-12-01

    Objective. In this study, we determined efficient head model sizes relative to predicted current densities in transcranial direct current stimulation (tDCS). Approach. Efficiency measures were defined based on a finite element (FE) simulations performed using nine human head models derived from a single MRI data set, having extents varying from 60%-100% of the original axial range. Eleven tissue types, including anisotropic white matter, and three electrode montages (T7-T8, F3-right supraorbital, Cz-Oz) were used in the models. Main results. Reducing head volume extent from 100% to 60%, that is, varying the model’s axial range from between the apex and C3 vertebra to one encompassing only apex to the superior cerebellum, was found to decrease the total modeling time by up to half. Differences between current density predictions in each model were quantified by using a relative difference measure (RDM). Our simulation results showed that {RDM} was the least affected (a maximum of 10% error) for head volumes modeled from the apex to the base of the skull (60%-75% volume). Significance. This finding suggested that the bone could act as a bioelectricity boundary and thus performing FE simulations of tDCS on the human head with models extending beyond the inferior skull may not be necessary in most cases to obtain reasonable precision in current density results.

  19. Skull Defects in Finite Element Head Models for Source Reconstruction from Magnetoencephalography Signals.

    PubMed

    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.

  20. 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

  1. Immunocompromised and immunocompetent mouse models for head and neck squamous cell carcinoma

    PubMed Central

    Lei, Zhen-ge; Ren, Xiao-hua; Wang, Sha-sha; Liang, Xin-hua; Tang, Ya-ling

    2016-01-01

    Mouse models can closely mimic human oral squamous epithelial carcinogenesis, greatly expand the in vivo research possibilities, and play a critical role in the development of diagnosis, monitoring, and treatment of head and neck squamous cell carcinoma. With the development of the recent research on the contribution of immunity/inflammation to cancer initiation and progression, mouse models have been divided into two categories, namely, immunocompromised and immunocompetent mouse models. And thus, this paper will review these two kinds of models applied in head and neck squamous cell carcinoma to provide a platform to understand the complicated histological, molecular, and genetic changes of oral squamous epithelial tumorigenesis. PMID:26869799

  2. Mental Models: Knowledge in the Head and Knowledge in the World.

    ERIC Educational Resources Information Center

    Jonassen, David H.; Henning, Philip

    1999-01-01

    Explores the utility of mental models as learning outcomes in using complex and situated learning environments. Describes two studies: one aimed at eliciting mental models in the heads of novice refrigeration technicians, and the other an ethnographic study eliciting knowledge and models within the community of experienced refrigeration…

  3. S-values calculated from a tomographic head/brain model for brain imaging

    NASA Astrophysics Data System (ADS)

    Chao, Tsi-chian; Xu, X. George

    2004-11-01

    A tomographic head/brain model was developed from the Visible Human images and used to calculate S-values for brain imaging procedures. This model contains 15 segmented sub-regions including caudate nucleus, cerebellum, cerebral cortex, cerebral white matter, corpus callosum, eyes, lateral ventricles, lenses, lentiform nucleus, optic chiasma, optic nerve, pons and middle cerebellar peduncle, skull CSF, thalamus and thyroid. S-values for C-11, O-15, F-18, Tc-99m and I-123 have been calculated using this model and a Monte Carlo code, EGS4. Comparison of the calculated S-values with those calculated from the MIRD (1999) stylized head/brain model shows significant differences. In many cases, the stylized head/brain model resulted in smaller S-values (as much as 88%), suggesting that the doses to a specific patient similar to the Visible Man could have been underestimated using the existing clinical dosimetry.

  4. Combined radio-colour contrast in the examination of ballistic head models.

    PubMed

    Schyma, C; Greschus, S; Urbach, H; Madea, B

    2012-07-01

    The conventional analysis of ballistic gelatine is performed by transillumination and scanning of 1-cm-thick slices. Previous research demonstrated the advantages of colour and radio contrast in gelatine for computed tomography (CT). The aim of this study was to determine whether this method could be applied to head models in order to facilitate their examination. Four head models of about 14 cm in diameter were prepared from two acryl hollow spheres and two polypropylene hollow spheres. Acryl paint was mixed with barium meal and sealed in a thin foil bag which was attached to the gelatine-filled sphere which was covered with about 3-mm-thick silicone. The head models were shot at using 9 mm × 19 expanding bullets from 4 m distance. The models were examined via multislice CT. The gelatine core was removed; the bullet track was photographed and cut into consecutive slices which were scanned optically. CT images were processed with Corel Photo-Paint. Optical and radiological images were analysed using the AxioVision software. The disruption of the gelatine within the head model was visualised by extensive distribution of paint up to the end of the finest cracks and fissures and along the whole bullet track. CT imaging with excellent radio contrast in the gelatine cracks caused by the temporary cavity allowed for multiplanar reconstruction. We conclude that the combination of colour contrast in gelatine with contrast material-enhanced CT facilitates accurate measurements in ballistic head models.

  5. Effects of geometric head model perturbations on the EEG forward and inverse problems.

    PubMed

    von Ellenrieder, Nicolás; Muravchik, Carlos H; Nehorai, Arye

    2006-03-01

    We study the effect of geometric head model perturbations on the electroencephalography (EEG) forward and inverse problems. Small magnitude perturbations of the shape of the head could represent uncertainties in the head model due to errors on images or techniques used to construct the model. They could also represent small scale details of the shape of the surfaces not described in a deterministic model, such as the sulci and fissures of the cortical layer. We perform a first-order perturbation analysis, using a meshless method for computing the sensitivity of the solution of the forward problem to the geometry of the head model. The effect on the forward problem solution is treated as noise in the EEG measurements and the Cramér-Rao bound is computed to quantify the effect on the inverse problem performance. Our results show that, for a dipolar source, the effect of the perturbations on the inverse problem performance is under the level of the uncertainties due to the spontaneous brain activity. Thus, the results suggest that an extremely detailed model of the head may be unnecessary when solving the EEG inverse problem.

  6. Emulating the Visual Receptive Field Properties of MST Neurons with a Template Model of Heading Estimation

    NASA Technical Reports Server (NTRS)

    Perrone, John A.; Stone, Leland S.

    1997-01-01

    We have previously proposed a computational neural-network model by which the complex patterns of retinal image motion generated during locomotion (optic flow) can be processed by specialized detectors acting as templates for specific instances of self-motion. The detectors in this template model respond to global optic flow by sampling image motion over a large portion of the visual field through networks of local motion sensors with properties similar to neurons found in the middle temporal (MT) area of primate extrastriate visual cortex. The model detectors were designed to extract self-translation (heading), self-rotation, as well as the scene layout (relative distances) ahead of a moving observer, and are arranged in cortical-like heading maps to perform this function. Heading estimation from optic flow has been postulated by some to be implemented within the medial superior temporal (MST) area. Others have questioned whether MST neurons can fulfill this role because some of their receptive-field properties appear inconsistent with a role in heading estimation. To resolve this issue, we systematically compared MST single-unit responses with the outputs of model detectors under matched stimulus conditions. We found that the basic physiological properties of MST neurons can be explained by the template model. We conclude that MST neurons are well suited to support heading estimation and that the template model provides an explicit set of testable hypotheses which can guide future exploration of MST and adjacent areas within the primate superior temporal sulcus.

  7. Head model and electrical source imaging: A study of 38 epileptic patients☆

    PubMed Central

    Birot, Gwénael; Spinelli, Laurent; Vulliémoz, Serge; Mégevand, Pierre; Brunet, Denis; Seeck, Margitta; Michel, Christoph M.

    2014-01-01

    Electrical source imaging (ESI) aims at reconstructing the electrical brain activity from scalp EEG. When applied to interictal epileptiform discharges (IEDs), this technique is of great use for identifying the irritative zone in focal epilepsies. Inaccuracies in the modeling of electro-magnetic field propagation in the head (forward model) may strongly influence ESI and lead to mislocalization of IED generators. However, a systematic study on the influence of the selected head model on the localization precision of IED in a large number of patients with known focus localization has not yet been performed. We here present such a performance evaluation of different head models in a dataset of 38 epileptic patients who have undergone high-density scalp EEG, intracranial EEG and, for the majority, subsequent surgery. We compared ESI accuracy resulting from three head models: a Locally Spherical Model with Anatomical Constraints (LSMAC), a Boundary Element Model (BEM) and a Finite Element Model (FEM). All of them were computed from the individual MRI of the patient and ESI was performed on averaged IED. We found that all head models provided very similar source locations. In patients having a positive post-operative outcome, at least 74% of the source maxima were within the resection. The median distance from the source maximum to the nearest intracranial electrode showing IED was 13.2, 15.6 and 15.6 mm for LSMAC, BEM and FEM, respectively. The study demonstrates that in clinical applications, the use of highly sophisticated and difficult to implement head models is not a crucial factor for an accurate ESI. PMID:25003030

  8. Aseptic osteonecrosis of the hip in the adult: current evidence on conservative treatment

    PubMed Central

    Klumpp, Raymond; Trevisan, Carlo

    2015-01-01

    Summary Treatment of Avascular Osteonecrosis (AVN) of the femoral head to prevent progression to an arthritic hip is a challenging subject. Many conservative treatment options have been proposed in the literature. Weight bearing restriction as a stand-alone therapy is insufficient in preventing disease progression but it may be useful when combined with pharmacological agents or surgery. Bisphosphonate treatment in AVN might be efficient in early stages of disease, however there are no clear recommendations on length of treatment and therapeutic dosage and, considered the limited evidence and potential side effects of treatment, it could be considered in a pre-collapse stage in selected cases. Current literature suggests that low molecular weight heparin could lower disease progression in idiopathic AVN with quality of evidence being very low. Also the evidence to support the use of statins or vasodilators in the treatment of osteonecrosis is very low and their use cannot be recommended. Extracorporeal shock wave therapy may improve pain and function in early stages of disease with a low evidence, but there doesn’t seem to be a significant change in time to the occurrence of femoral head collapse. Only one study has been conducted with pulsed electromagnetic fields therefore no recommendation can be given on clinical use of PEF in AVN. Evidence on hyperbaric oxygen therapy in the treatment of AVN is very limited and the high cost of treatment and the limited availability of structures that can provide the service poses other concerns about its feasibility. Based on current evidence, conservative treatment may be considered in early stages of asymptomatic AVN instead of observation only. PMID:27134631

  9. Osteonecrosis of the jaws and bisphosphonates. Report of three cases.

    PubMed

    Pastor-Zuazaga, Daniel; Garatea-Crelgo, Joaquín; Martino-Gorbea, Raúl; Etayo-Pérez, Amaya; Sebastián-López, Cristina

    2006-01-01

    Bisphosphonates are recently acquiring increasing relevance in the treatment of several diseases. In line with the increased use of these compounds, cases of mandibular osteonecrosis, and to a lesser extent, maxillary osteonecrosis, are being reported. This necrosis is difficult to treat in patients who usually have a previously limited quality of life. A surgical performance carried out by oral and maxillofacial surgeons, stomatologists and odontologists might lead to bone exposure. A treatment based on conservation and as harmless as possible seems to be the most advisable way of acting with these patients in order to minimize the incidence and treat the complications, once the lesions have been ascertained. We report three cases treated in our service of osteonecrosis of the jaws after exodontics. This side effect should be remembered before starting any surgical treatment in these patients.

  10. [Sunitinib and zoledronic acid induced osteonecrosis of the jaw].

    PubMed

    Soós, Balázs; Vajta, László; Szalma, József

    2015-11-15

    The tendency for bisphosphonate and non-bisphosphonate (eg.: antiresorptive or anti-angiogenesis drugs) induced osteonecrosis is increasing. Treatment of these patients is a challenge both for dentists and for oral and maxillofacial surgeons. Cooperation with the drug prescribing general medicine colleagues to prevent osteonecrosis is extremely important. Furthermore, prevention should include dental focus elimination, oral hygienic instructions and education, dental follow-up and, in case of manifest necrosis, referral to maxillofacial departments. Authors outline the difficulties of conservative and surgical treatment of a patient with sunitinib and zoledronic acid induced osteonecrosis. The patient became symptomless and the operated area healed entirely six and twelve months postoperatively. A long term success further follow-up is necessary to verify long-term success.

  11. A dynamical model for reflex activated head movements in the horizontal plane

    NASA Technical Reports Server (NTRS)

    Peng, G. C.; Hain, T. C.; Peterson, B. W.

    1996-01-01

    We present a controls systems model of horizontal-plane head movements during perturbations of the trunk, which for the first time interfaces a model of the human head with neural feedback controllers representing the vestibulocollic (VCR) and the cervicocollic (CCR) reflexes. This model is homeomorphic such that model structure and parameters are drawn directly from anthropomorphic, biomechanical and physiological studies. Using control theory we analyzed the system model in the time and frequency domains, simulating neck movement responses to input perturbations of the trunk. Without reflex control, the head and neck system produced a second-order underdamped response with a 5.2 dB resonant peak at 2.1 Hz. Adding the CCR component to the system dampened the response by approximately 7%. Adding the VCR component dampened head oscillations by 75%. The VCR also improved low-frequency compensation by increasing the gain and phase lag, creating a phase minimum at 0.1 Hz and a phase peak at 1.1 Hz. Combining all three components (mechanics, VCR and CCR) linearly in the head and neck system reduced the amplitude of the resonant peak to 1.1 dB and increased the resonant frequency to 2.9 Hz. The closed loop results closely fit human data, and explain quantitatively the characteristic phase peak often observed.

  12. Development of Head Injury Assessment Reference Values Based on NASA Injury Modeling

    NASA Technical Reports Server (NTRS)

    Somers, Jeffrey T.; Melvin, John W.; Tabiei, Ala; Lawrence, Charles; Ploutz-Snyder, Robert; Granderson, Bradley; Feiveson, Alan; Gernhardt, Michael; Patalak, John

    2011-01-01

    NASA is developing a new capsule-based, crewed vehicle that will land in the ocean, and the space agency desires to reduce the risk of injury from impact during these landings. Because landing impact occurs for each flight and the crew might need to perform egress tasks, current injury assessment reference values (IARV) were deemed insufficient. Because NASCAR occupant restraint systems are more effective than the systems used to determine the current IARVs and are similar to NASA s proposed restraint system, an analysis of NASCAR impacts was performed to develop new IARVs that may be more relevant to NASA s context of vehicle landing operations. Head IARVs associated with race car impacts were investigated by completing a detailed analysis of all of the 2002-2008 NASCAR impact data. Specific inclusion and exclusion criteria were used to select 4071 impacts from the 4015 recorder files provided (each file could contain multiple impact events). Of the 4071 accepted impacts, 274 were selected for numerical simulation using a custom NASCAR restraint system and Humanetics Hybrid-III 50th percentile numerical dummy model in LS-DYNA. Injury had occurred in 32 of the 274 selected impacts, and 27 of those injuries involved the head. A majority of the head injuries were mild concussions with or without brief loss of consciousness. The 242 non-injury impacts were randomly selected and representative of the range of crash dynamics present in the total set of 4071 impacts. Head dynamics data (head translational acceleration, translational change in velocity, rotational acceleration, rotational velocity, HIC-15, HIC-36, and the Head 3ms clip) were filtered according to SAE J211 specifications and then transformed to a log scale. The probability of head injury was estimated using a separate logistic regression analysis for each log-transformed predictor candidate. Using the log transformation constrains the estimated probability of injury to become negligible as IARVs approach

  13. The role of blood vessels in high-resolution volume conductor head modeling of EEG

    PubMed Central

    Fiederer, L.D.J.; Vorwerk, J.; Lucka, F.; Dannhauer, M.; Yang, S.; Dümpelmann, M.; Schulze-Bonhage, A.; Aertsen, A.; Speck, O.; Wolters, C.H.; Ball, T.

    2016-01-01

    Reconstruction of the electrical sources of human EEG activity at high spatiotemporal accuracy is an important aim in neuroscience and neurological diagnostics. Over the last decades, numerous studies have demonstrated that realistic modeling of head anatomy improves the accuracy of source reconstruction of EEG signals. For example, including a cerebrospinal fluid compartment and the anisotropy of white matter electrical conductivity were both shown to significantly reduce modeling errors. Here, we for the first time quantify the role of detailed reconstructions of the cerebral blood vessels in volume conductor head modeling for EEG. To study the role of the highly arborized cerebral blood vessels, we created a submillimeter head model based on ultra-high-field-strength (7 T) structural MRI datasets. Blood vessels (arteries and emissary/intraosseous veins) were segmented using Frangi multi-scale vesselness filtering. The final head model consisted of a geometry-adapted cubic mesh with over 17 × 106 nodes. We solved the forward model using a finite-element-method (FEM) transfer matrix approach, which allowed reducing computation times substantially and quantified the importance of the blood vessel compartment by computing forward and inverse errors resulting from ignoring the blood vessels. Our results show that ignoring emissary veins piercing the skull leads to focal localization errors of approx. 5 to 15 mm. Large errors (>2 cm) were observed due to the carotid arteries and the dense arterial vasculature in areas such as in the insula or in the medial temporal lobe. Thus, in such predisposed areas, errors caused by neglecting blood vessels can reach similar magnitudes as those previously reported for neglecting white matter anisotropy, the CSF or the dura — structures which are generally considered important components of realistic EEG head models. Our findings thus imply that including a realistic blood vessel compartment in EEG head models will be helpful to

  14. The role of blood vessels in high-resolution volume conductor head modeling of EEG.

    PubMed

    Fiederer, L D J; Vorwerk, J; Lucka, F; Dannhauer, M; Yang, S; Dümpelmann, M; Schulze-Bonhage, A; Aertsen, A; Speck, O; Wolters, C H; Ball, T

    2016-03-01

    Reconstruction of the electrical sources of human EEG activity at high spatio-temporal accuracy is an important aim in neuroscience and neurological diagnostics. Over the last decades, numerous studies have demonstrated that realistic modeling of head anatomy improves the accuracy of source reconstruction of EEG signals. For example, including a cerebro-spinal fluid compartment and the anisotropy of white matter electrical conductivity were both shown to significantly reduce modeling errors. Here, we for the first time quantify the role of detailed reconstructions of the cerebral blood vessels in volume conductor head modeling for EEG. To study the role of the highly arborized cerebral blood vessels, we created a submillimeter head model based on ultra-high-field-strength (7T) structural MRI datasets. Blood vessels (arteries and emissary/intraosseous veins) were segmented using Frangi multi-scale vesselness filtering. The final head model consisted of a geometry-adapted cubic mesh with over 17×10(6) nodes. We solved the forward model using a finite-element-method (FEM) transfer matrix approach, which allowed reducing computation times substantially and quantified the importance of the blood vessel compartment by computing forward and inverse errors resulting from ignoring the blood vessels. Our results show that ignoring emissary veins piercing the skull leads to focal localization errors of approx. 5 to 15mm. Large errors (>2cm) were observed due to the carotid arteries and the dense arterial vasculature in areas such as in the insula or in the medial temporal lobe. Thus, in such predisposed areas, errors caused by neglecting blood vessels can reach similar magnitudes as those previously reported for neglecting white matter anisotropy, the CSF or the dura - structures which are generally considered important components of realistic EEG head models. Our findings thus imply that including a realistic blood vessel compartment in EEG head models will be helpful to

  15. A Three-Dimensional Computational Human Head Model That Captures Live Human Brain Dynamics.

    PubMed

    Ganpule, Shailesh; Daphalapurkar, Nitin P; Ramesh, Kaliat T; Knutsen, Andrew K; Pham, Dzung L; Bayly, Philip V; Prince, Jerry L

    2017-04-10

    Diffuse axonal injury (DAI) is a debilitating consequence of traumatic brain injury (TBI) attributed to abnormal stretching of axons caused by blunt head trauma or acceleration of the head. We developed an anatomically accurate, subject-specific, three-dimensional (3D) computational model of the human brain, and used it to study the dynamic deformations in the substructures of the brain when the head is subjected to rotational accelerations. The computational head models use anatomy and morphology of the white matter fibers obtained using MRI. Subject-specific full-field shearing motions in live human brains obtained through a recently developed tagged MRI imaging technique are then used to validate the models by comparing the measured and predicted heterogeneous dynamic mechanical response of the brain. These results are used to elucidate the dynamics of local shearing deformations in the brain substructures caused by rotational acceleration of the head. Our work demonstrates that the rotational dynamics of the brain has a timescale of ∼100 ms as determined by the shearing wave speeds, and thus the injuries associated with rotational accelerations likely occur over these time scales. After subject-specific validation using the live human subject data, a representative subject-specific head model is used to simulate a real life scenario that resulted in a concussive injury. Results suggest that regions of the brain, in the form of a toroid, encompassing the white matter, the cortical gray matter, and outer parts of the limbic system have a higher susceptibility to injury under axial rotations of the head.

  16. Nontraumatic osteonecrosis of the distal pole of the scaphoid

    PubMed Central

    Garg, Bhavuk; Gupta, Himanshu; Kotwal, Prakash P

    2011-01-01

    Post traumatic osteonecrosis of distal pole of scaphoid is very rare. We present a case of 34 years old male, drill operator by occupation with nontraumatic osteonecrosis of distal pole of the scaphoid. The patient was managed conservatively and was kept under regular follow-up every three months. The patient was also asked to change his profession. Two years later, the patient had no pain and had mild restriction of wrist movements (less than 15 degrees in either direction). The radiographs revealed normal density of the scaphoid suggesting revascularization. PMID:21430877

  17. Bisphosphonates and osteonecrosis: an open matter

    PubMed Central

    Vescovi, Paolo

    2012-01-01

    Summary Osteonecrosis of the Jaw (ONJ) in patients on long-term Bisphosphonate Therapy (BPT) is being reported in the last ten years in the literature with increasing frequency. The therapy for this condition is a real dilemma. Temporary suspension of BPT offers no short term benefits, hyperbaric oxygen has no proven efficiency and therefore is not recommended, intermittent or continuous antibiotic with surgical debridement can be beneficial to palliate the symptoms. Er:YAG laser can be used to eliminate necrotic portions of the bone by partial or total resection of the jaws as an alternative to conventional rotary tools. The high degree of affinity of this wavelength for water and hydroxyapatite means the soft tissue and bone can both be treated. The technique can also be used for conservative interventions by gradually evaporating the part of necrotic bone, getting close to the healthy area. One certain advantage of the Er:YAG laser is its bactericidal and biostimulatory action, inducing the healing of the soft tissues and the bone, quicker than in conventional treatments. In conclusion, from our experience, it is possible to observe that an early conservative surgical approach with Er:YAG laser associated to biostimulation, LLLT (Low Level Laser Therapy), for BRONJ could be considered as more efficacious in comparison to medical therapy or other techniques. PMID:23289026

  18. Does Head Start differentially benefit children with risks targeted by the program’s service model?☆

    PubMed Central

    Miller, Elizabeth B.; Farkas, George; Duncan, Greg J.

    2015-01-01

    Data from the Head Start Impact Study (N = 3540) were used to test for differential benefits of Head Start after one program year and after kindergarten on pre-academic and behavior outcomes for children at risk in the domains targeted by the program’s comprehensive services. Although random assignment to Head Start produced positive treatment main effects on children’s pre-academic skills and behavior problems, residualized growth models showed that random assignment to Head Start did not differentially benefit the pre-academic skills of children with risk factors targeted by the Head Start service model. The models showed detrimental impacts of Head Start for maternal-reported behavior problems of high-risk children, but slightly more positive impacts for teacher-reported behavior. Policy implications for Head Start are discussed. PMID:26379369

  19. Mathematical modeling of the head-disk interface (abstract)

    NASA Astrophysics Data System (ADS)

    Crone, Robert M.; Jhon, Myung S.

    1993-05-01

    State-of-the-art theoretical and numerical techniques required to simulate the head-disk interface (HDI) of future magnetic storage devices is presented. The severity of operating conditions (i.e., attempts to achieve flying heights as low as 40 nm) pose several challenges. Large transient pressure gradients can be established within air bearing leading to numerical oscillations as well as to increased program execution times. Enhanced gaseous rarefaction effects must also be incorporated into the analysis. In the present study, accurate nonoscillatory air bearing pressure distributions were obtained using a high resolution finite element algorithm to solve the generalized Reynolds equation. Higher order gaseous rarefaction effects are incorporated into generalized Reynolds equations using the total mass flow rate coefficient predicted from the linearized Boltzmann equation. The form of the generalized Reynolds equation that is presented in this paper is an improved version of the continued fraction approximation previously proposed by Crone et al.1 A simple scaling analysis, which is based upon the results of the linearized Boltzmann equation, will also be presented to study the effect of slider miniaturization, as well as to obtain a novel interpretation of accelerated wear and accelerated flyability test results.

  20. Five-layer realistic head model based on inhomogeneous and anisotropic conductivity distribution of different tissues

    NASA Astrophysics Data System (ADS)

    Yan, Dandan; Zhang, Jianwei; Wu, Weijuan; Ying, Xiaoyan; Wu, Xiangping

    2009-10-01

    This paper is focused on the sophisticated realistic head modeling based on inhomogeneous and anisotropic conductivity distribution of the head tissues. The finite element method (FEM) was used to model the five-layer head volume conductor models with hexahedral elements from segmentation and mapping of DT-MRI data. Then the inhomogeneous conductivities of the scalp, CSF and gray matter tissue were distributed according a normal distribution based on the mean value of respective tissues. The electric conductivity of the brain tissues dictates different inhomogeneous and anisotropic at some different microscopic levels. Including the inhomogeneous and anisotropy of the tissue would improve the accuracy of the MREIT, EEG and MEG problems in the simulation research.

  1. Modeling Time Resolved Light Propagation Inside a Realistic Human Head Model

    PubMed Central

    Bazrafkan, Sh; Kazemi, K

    2014-01-01

    Background: Near infrared spectroscopy imaging is one of the new techniques used for investigating structural and functionality of different body tissues. This is done by injecting light into the medium and measuring the photon intensity at the surface of the tissue. Methods: In this paper the different medical applications, various imaging and simulation techniques of NIRS imaging is described. Each method is introduced and discussed. Then, the optimized model is prepared for numerical simulations. In this paper, the finite element method is used for solving the diffusion equation numerically. Results: Diffusion equation was solved for realistic human head model using finite element approach for a point light source and time resolved case. The photon intensity distribution in different head layers has been shown and the intensity orientation via the CSF layer has been illustrated. Conclusion: Simulating the photon transformation inside the tissue is essential for investigating the NIRS imaging technique. The finite element approach is a fast and accurate method for simulating this fact. The time resolved approach of this technique could illustrate the photon migration and intensity orientation in the tissue for time dependent light sources in tissues. PMID:25505770

  2. Solving the forward problem in EEG source analysis by spherical and fdm head modeling: a comparative analysis - biomed 2009.

    PubMed

    Vatta, Federica; Meneghini, Fabio; Esposito, Fabrino; Mininel, Stefano; Di Salle, Francesca

    2009-01-01

    Neural source localization techniques based on electroencephalography (EEG) use scalp potential data to infer the location of underlying neural activity. This procedure entails modeling the sources of EEG activity and modeling the head volume conduction process to link the modeled sources to the EEG, solving the so called EEG forward problem, and reconstructing the brain electrical activity from recorded EEG data, solving the EEG inverse problem. Many factors affect the accuracy of the forward and hence of the inverse problem solution, one of them is the shape of the head model. Realistic head models can lead to more accurate forward problem solutions, but imply heavier computational burdens in comparison to spherical models. Conversely, inverse solutions require the forward model to be computationally efficient. The aim of this study is to investigate the different general potentialities, in terms of EEG source reconstruction, which can be achieved adopting realistic or spherical geometries in head modeling. Previous studies in the literature analyzed the effect of head model geometry presenting results for particular cases of head models. In this paper, we re-address the effect of realistic geometry in head modeling, seeking for more general results by adopting the Montreal Neurological Institute (MNI) phantom model to represent a whole family of realistic head models. This paper presents results of a computer simulation study in which the potentialities of two different four-shell head models are compared, the realistic MNI-based FDM and the corresponding sensor-fitted spherical-shaped model, by means of the Point Spread Function (PSF) correlation maps, with a quantitative analysis of the accuracy in EEG source reconstruction given by head modeling refinement from the spherical to the more complex realistic FDM head modeling.

  3. Modeling smooth muscle myosin's two heads: long-lived enzymatic roles and phosphorylation-dependent equilibria.

    PubMed

    Walcott, Sam; Warshaw, David M

    2010-08-09

    Smooth muscle myosin has two heads, each capable of interacting with actin to generate force and/or motion as it hydrolyzes ATP. These heads are inhibited when their associated regulatory light chain is unphosphorylated (0P), becoming active and hydrolyzing ATP maximally when phosphorylated (2P). Interestingly, with only one of the two regulatory light chains phosphorylated (1P), smooth muscle myosin is active but its ATPase rate is <2P. To explain published 1P single ATP turnover and steady-state ATPase activities, we propose a kinetic model in which 1P myosin exists in an equilibrium between being fully active (2P) and inhibited (0P). Based on the single ATP turnover data, we also propose that each 2P head adopts a hydrolytic role distinct from its partner at any point in time, i.e., one head strongly binds actin and hydrolyzes ATP at its actin-activated rate while the other weakly binds actin. Surprisingly, the heads switch roles slowly (<0.1 s(-1)), suggesting that their activities are not independent. The phosphorylation-dependent equilibrium between active and inhibited states and the hydrolytic role that each head adopts during its interaction with actin may have implications for understanding regulation and mechanical performance of other members of the myosin family of molecular motors.

  4. Of Lice and Math: Using Models to Understand and Control Populations of Head Lice

    PubMed Central

    Laguna, Mara Fabiana; Risau-Gusman, Sebastián

    2011-01-01

    In this paper we use detailed data about the biology of the head louse (pediculus humanus capitis) to build a model of the evolution of head lice colonies. Using theory and computer simulations, we show that the model can be used to assess the impact of the various strategies usually applied to eradicate head lice, both conscious (treatments) and unconscious (grooming). In the case of treatments, we study the difference in performance that arises when they are applied in systematic and non-systematic ways. Using some reasonable simplifying assumptions (as random mixing of human groups and the same mobility for all life stages of head lice other than eggs) we model the contagion of pediculosis using only one additional parameter. It is shown that this parameter can be tuned to obtain collective infestations whose characteristics are compatible with what is given in the literature on real infestations. We analyze two scenarios: One where group members begin treatment when a similar number of lice are present in each head, and another where there is one individual who starts treatment with a much larger threshold (“superspreader”). For both cases we assess the impact of several collective strategies of treatment. PMID:21799752

  5. Segmentation of magnetic resonance images to construct human head model for diffuse optical imaging

    NASA Astrophysics Data System (ADS)

    Kurihara, Kazuki; Kawaguchi, Hiroshi; Takahashi, Yosuke; Obata, Takayuki; Okada, Eiji

    2011-07-01

    The brain activation image obtained by diffuse optical tomography (DOT) is obtained by solving inverse problem using the spatial sensitivity profile (SSP). The SSP can be obtained from the analysis of the light propagation using threedimensional head models. The head model is based upon segmented magnetic resonance (MR) image and there are several types of software based on binarization for segmentation of MR head images. We segmented superficial tissues which effect the light propagation in human head from MR images acquired with FATSAT and FIESTA pulse sequences by using region growing algorithm and morphological operation to facilitate the construction of the individual head models for DOT. The pixel intensity distribution of these images has appropriate characteristics to extract the superficial tissues by using algorithm based on binarization. The result of extraction was compared with the extraction from T2-weighted image which is commonly used to extract superficial tissues. The result of extraction from FATSAT or FIESTA image agree well with ground truth determined by manual segmentation.

  6. Of lice and math: using models to understand and control populations of head lice.

    PubMed

    Laguna, María Fabiana; Laguna, Mara Fabiana; Risau-Gusman, Sebastián

    2011-01-01

    In this paper we use detailed data about the biology of the head louse (pediculus humanus capitis) to build a model of the evolution of head lice colonies. Using theory and computer simulations, we show that the model can be used to assess the impact of the various strategies usually applied to eradicate head lice, both conscious (treatments) and unconscious (grooming). In the case of treatments, we study the difference in performance that arises when they are applied in systematic and non-systematic ways. Using some reasonable simplifying assumptions (as random mixing of human groups and the same mobility for all life stages of head lice other than eggs) we model the contagion of pediculosis using only one additional parameter. It is shown that this parameter can be tuned to obtain collective infestations whose characteristics are compatible with what is given in the literature on real infestations. We analyze two scenarios: One where group members begin treatment when a similar number of lice are present in each head, and another where there is one individual who starts treatment with a much larger threshold ("superspreader"). For both cases we assess the impact of several collective strategies of treatment.

  7. High-Dose Corticosteroid Use and Risk of Hip Osteonecrosis: Meta-Analysis and Systematic Literature Review.

    PubMed

    Mont, Michael A; Pivec, Robert; Banerjee, Samik; Issa, Kimona; Elmallah, Randa K; Jones, Lynne C

    2015-09-01

    The effect of varying corticosteroid regimens on hip osteonecrosis incidence remains unclear. We performed a meta-analysis and systematic literature review to determine osteonecrosis occurrences in patients taking corticosteroids at varying mean and cumulative doses and treatment durations, and whether medical diagnoses affected osteonecrosis incidence. Fifty-seven studies (23,561 patients) were reviewed. Regression analysis determined significance between corticosteroid usage and osteonecrosis incidence. Osteonecrosis incidence was 6.7% with corticosteroid treatment of >2 g (prednisone-equivalent). Systemic lupus erythematosus patients had positive correlations between dose and osteonecrosis incidence. Each 10 mg/d increase was associated with a 3.6% increase in osteonecrosis rate, and >20 mg/d resulted in a higher osteonecrosis incidence. Clinicians must be wary of osteonecrosis in patients on high corticosteroid regimens, particularly in systematic lupus erythematosus.

  8. Development of New, Low-Head Hydropower Turbine - Modeling & Laboratory Test DE-EE0005426

    SciTech Connect

    Krouse, Wayne

    2014-12-05

    Hydro Green Energy, LLC (HGE) will complete the design, fabrication and laboratory testing of a scaled, vertically stackable, low-head hydropower turbine called the Modular Bulb Turbine (MBT). HGE will also complete a summary report that includes the laboratory testing results and analysis of the tests. Project Goals: Design, model and test modular bulb turbine for installation in numerous HGE low-head hydropower projects at non-powered USACE dams. Project Results: The sub-scale prototype was tested successfully at a leading US hydraulic laboratory. Laboratory data results agreed well with predicted results from numerical modeling.

  9. Effect of D-003, a Mixture of High Molecular Weight Aliphatic Acids, on Glucocorticoid- and Lipopolysaccharides (LPS)-Induced Osteonecrosis.

    PubMed

    Noa, Miriam; Más, Rosa; Valle, Maikel; Mendoza, Sarahí; Mendoza, Nilda

    2012-01-01

    Osteonecrosis (ON) is characterized through the impairment of osseous blood flow that leads to the collapse of femur head. Corticoid-induced ON in rats and lipopolysaccharide (LPS)-induced in rabbits are useful models to assess the efficacy of potential treatments on this disease. D-003 inhibits the mevalonate pathway, lipid peroxidation and prevents osteoporosis in rats through increasing the osteoclast apoptosis. This study investigated the effects of D-003 on corticoid- and LPS-induced ON in rats and rabbits. Corticoid-induced ON: Rats were randomized into five groups. A negative control and four groups treated with prednisolone 6 mg/Kg: a positive control and three treated with D-003 (5, 25 and 200 mg/Kg) for 80 days. All positive controls presented ON areas. D-003 significantly reduced the numbers and proportions of ON lesions, as compared to the positive control group. LPS-induced ON in rabbits: Rabbits were randomized into five groups: a negative control and four injected with a single intra-venous injection of LPS (10 μg/Kg) including a positive control and three with D-003 (5, 25 and 200 mg/Kg) for 30 days. ON was seen in all positive controls. The incidence of ON and the number of ON lesions in the groups treated with D-003 (25 and 200 mg/Kg) was significantly lower compared to the positive controls. LPS injection significantly increased the size of bone marrow fat cells in positive controls and such increase was significantly decreased by D-003. In conclusion, D-003 reduced ON lesions in corticoid-and LPS-induced ON and also the size of bone marrow fat cells in rabbits with LPS.

  10. A dynamic factor modeling framework for analyzing multiple groundwater head series simultaneously

    NASA Astrophysics Data System (ADS)

    Berendrecht, W. L.; van Geer, F. C.

    2016-05-01

    In this paper we present an approach in which we combine a dynamic factor model (DFM) and predefined response functions to analyze a set of groundwater head series simultaneously. Each groundwater head series is decomposed into: (a) one or more deterministic components as a response to known driving forces, (b) one or more common dynamic factors, representing spatial patterns not related to any of the input series and (c) one specific dynamic factor for each groundwater head series, describing unique variation for that series. The approach reduces the degrees of freedom for each response function, enables the application to irregular observed data, and exploits the correlation between residual series of a set of groundwater head series. The common dynamic factors may be interpreted as spatial patterns due to e.g. limitations in the model specification or concept, spatially correlated errors in input variables, or driving forces which have not been included in the model. In the latter case the model can be applied in the context of an alarming system, e.g. to monitor regional trends. The specific dynamic factor depicts the variation of a particular groundwater head series that cannot be related to any other time series of the set nor to any input series. Therefore the specific dynamic factor is suitable for analyzing local variations and detecting incidental measurement errors, for example in a quality control procedure. The DFM framework is illustrated with a set of 8 groundwater head series and applied for filling gaps in time series, reconstructing high-frequency data, and detecting outliers.

  11. Computational representation of a realistic head and brain volume conductor model: electroencephalography simulation and visualization study.

    PubMed

    Kybartaite, Asta

    2012-11-01

    Computational head and brain volume conductor modeling is a practical and non-invasive method to investigate neuroelectrical activity in the brain. Anatomical structures included in a model affect the flow of volume currents and the resulting scalp surface potentials. The influence of different tissues within the head on scalp surface potentials was investigated by constructing five highly detailed, realistic head models from segmented and processed Visible Human Man digital images. The models were: (1) model with 20 different tissues, that is, skin, dense connective tissue (fat), aponeurosis (muscle), outer, middle and inner tables of the scalp, dura matter, arachnoid layer (including cerebrospinal fluid), pia matter, six cortical layers, eye tissue, muscle around the eye, optic nerve, temporal muscle, white matter and internal air, (2) model with three main inhomogeneities, that is, scalp, skull, brain, (3) model with homogeneous scalp and remaining inhomogeneities, (4) model with homogeneous skull and remaining inhomogeneities, and (5) model with homogeneous brain matter and remaining inhomogeneities. Scalp potentials because of three different dipolar sources in the parietal-occipital lobe were computed for all five models. Results of a forward solution revealed that tissues included in the model and the dipole source location directly affect the simulated scalp surface potentials. The major finding indicates that significant change in the scalp surface potentials is observed when the brain's distinctions are removed. The other modifications, for example, layers of the scalp and skull are important too, but they have less effect on the overall results.

  12. Bone end sclerosis in renal osteodystrophy simulating osteonecrosis

    SciTech Connect

    Van Lewis, L.; Keats, T.E.

    1982-08-01

    Osteosclerosis of the bone ends is an unusual manifestation of renal osteodystrophy. In evaluating this finding one should be careful to exclude clinical and radiographic evidence for osteonecrosis. In the two known cases of this entity, bone end sclerosis has been found to develop over one to two years with symmetrical involvement of multiple bones.

  13. Risk Factors for Osteonecrosis of the Jaws

    PubMed Central

    Barasch, A.; Cunha-Cruz, J.; Curro, F.A.; Hujoel, P.; Sung, A.H.; Vena, D.; Voinea-Griffin, A.E.; Beadnell, Steven; Craig, Ronald G.; DeRouen, Timothy; Desaranayake, Ananda; Gilbert, Ann; Gilbert, Gregg H.; Goldberg, Ken; Hauley, Richard; Hashimoto, Mariko; Holmes, Jon; Latzke, Brooke; Leroux, Brian; Lindblad, Anne; Richman, Joshua; Safford, Monika; Ship [deceased], Jonathan; Thompson, Van P.; Williams, O. Dale; Yin, Wanrong

    2011-01-01

    Case reports and cohort studies have linked bisphosphonate therapy and osteonecrosis of the jaws (ONJ), but neither causality nor specific risks for lesion development have been clearly established. We conducted a 1:3 case-control study with three dental Practice-based Research Networks, using dentist questionnaires and patient interviews for collection of data on bisphosphonate therapy, demographics, co-morbidities, and dental and medical treatments. Multivariable logistic regression analyses tested associations between bisphosphonate use and other risk factors with ONJ. We enrolled 191 ONJ cases and 573 controls in 119 dental practices. Bisphosphonate use was strongly associated with ONJ (odds ratios [OR] 299.5 {95%CI 70.0-1282.7} for intravenous [IV] use and OR = 12.2 {4.3-35.0} for oral use). Risk markers included local suppuration (OR = 7.8 {1.8-34.1}), dental extraction (OR = 7.6 {2.4-24.7}), and radiation therapy (OR = 24.1 {4.9-118.4}). When cancer patients (n = 143) were excluded, bisphosphonate use (OR = 7.2 {2.1-24.7}), suppuration (OR = 11.9 {2.0-69.5}), and extractions (OR = 6.6 {1.6-26.6}) remained associated with ONJ. Higher risk of ONJ began within 2 years of bisphosphonate initiation and increased four-fold after 2 years. Both IV and oral bisphosphonate use were strongly associated with ONJ. Duration of treatment > 2 years; suppuration and dental extractions were independent risk factors for ONJ. PMID:21317246

  14. A Neural Model of How the Brain Computes Heading from Optic Flow in Realistic Scenes

    ERIC Educational Resources Information Center

    Browning, N. Andrew; Grossberg, Stephen; Mingolla, Ennio

    2009-01-01

    Visually-based navigation is a key competence during spatial cognition. Animals avoid obstacles and approach goals in novel cluttered environments using optic flow to compute heading with respect to the environment. Most navigation models try either explain data, or to demonstrate navigational competence in real-world environments without regard…

  15. EEG/MEG error bounds for a dynamic dipole source with a realistic head model.

    PubMed

    Muravchik, C; Bria, O; Nehorai, A

    2000-06-01

    This work presents the background and derivation of Cramér-Rao bounds on the errors of estimating the parameters (moment and location) of a dynamic current dipole source using data from electro- and magneto-encephalography. A realistic head model, based on knowledge of surfaces separating tissues of different conductivities, is used.

  16. BrainK for Structural Image Processing: Creating Electrical Models of the Human Head.

    PubMed

    Li, Kai; Papademetris, Xenophon; Tucker, Don M

    2016-01-01

    BrainK is a set of automated procedures for characterizing the tissues of the human head from MRI, CT, and photogrammetry images. The tissue segmentation and cortical surface extraction support the primary goal of modeling the propagation of electrical currents through head tissues with a finite difference model (FDM) or finite element model (FEM) created from the BrainK geometries. The electrical head model is necessary for accurate source localization of dense array electroencephalographic (dEEG) measures from head surface electrodes. It is also necessary for accurate targeting of cerebral structures with transcranial current injection from those surface electrodes. BrainK must achieve five major tasks: image segmentation, registration of the MRI, CT, and sensor photogrammetry images, cortical surface reconstruction, dipole tessellation of the cortical surface, and Talairach transformation. We describe the approach to each task, and we compare the accuracies for the key tasks of tissue segmentation and cortical surface extraction in relation to existing research tools (FreeSurfer, FSL, SPM, and BrainVisa). BrainK achieves good accuracy with minimal or no user intervention, it deals well with poor quality MR images and tissue abnormalities, and it provides improved computational efficiency over existing research packages.

  17. Earnings Profiles of Department Heads: Comparing Cross-Sectional and Panel Models.

    ERIC Educational Resources Information Center

    Ragan, James F., Jr.; Rehman, Qazi Najeeb

    1996-01-01

    A cross-sectional study of 842 faculty who served as department heads between 1965-92 was compared with 170 in a panel study for whom earnings were estimated using a personal effects model. The average chair received a 12% wage premium for administrative service. Skill depreciation was most severe and wage growth most adversely affected in the…

  18. Intensive Evaluation of Head Start Implementation in the Tucson Early Education Model.

    ERIC Educational Resources Information Center

    Rentfrow, Robert K.

    As part of the national Head Start Planned Variation Study, this study used a relatively small sample in an intensive evaluation of program implementation in one field community using the Tucson Early Education Model (TEEM). A modified Solomon four-group research design formed the organization framework. Evaluation of six TEEM classrooms and two…

  19. BrainK for Structural Image Processing: Creating Electrical Models of the Human Head

    PubMed Central

    Li, Kai; Papademetris, Xenophon; Tucker, Don M.

    2016-01-01

    BrainK is a set of automated procedures for characterizing the tissues of the human head from MRI, CT, and photogrammetry images. The tissue segmentation and cortical surface extraction support the primary goal of modeling the propagation of electrical currents through head tissues with a finite difference model (FDM) or finite element model (FEM) created from the BrainK geometries. The electrical head model is necessary for accurate source localization of dense array electroencephalographic (dEEG) measures from head surface electrodes. It is also necessary for accurate targeting of cerebral structures with transcranial current injection from those surface electrodes. BrainK must achieve five major tasks: image segmentation, registration of the MRI, CT, and sensor photogrammetry images, cortical surface reconstruction, dipole tessellation of the cortical surface, and Talairach transformation. We describe the approach to each task, and we compare the accuracies for the key tasks of tissue segmentation and cortical surface extraction in relation to existing research tools (FreeSurfer, FSL, SPM, and BrainVisa). BrainK achieves good accuracy with minimal or no user intervention, it deals well with poor quality MR images and tissue abnormalities, and it provides improved computational efficiency over existing research packages. PMID:27293419

  20. Magnetic Nanoparticle-Based Hyperthermia for Head & Neck Cancer in Mouse Models

    PubMed Central

    Zhao, Qun; Wang, Luning; Cheng, Rui; Mao, Leidong; Arnold, Robert D.; Howerth, Elizabeth W.; Chen, Zhuo G.; Platt, Simon

    2012-01-01

    In this study, magnetic iron oxide nanoparticle induced hyperthermia is applied for treatment of head and neck cancer using a mouse xenograft model of human head and neck cancer (Tu212 cell line). A hyperthermia system for heating iron oxide nanoparticles was developed by using alternating magnetic fields. Both theoretical simulation and experimental studies were performed to verify the thermotherapy effect. Experimental results showed that the temperature of the tumor center has dramatically elevated from around the room temperature to about 40oC within the first 5-10 minutes. Pathological studies demonstrate epithelial tumor cell destruction associated with the hyperthermia treatment. PMID:22287991

  1. MRI-based anatomical model of the human head for specific absorption rate mapping

    PubMed Central

    Makris, Nikos; Angelone, Leonardo; Tulloch, Seann; Sorg, Scott; Kaiser, Jonathan; Kennedy, David

    2009-01-01

    In this study, we present a magnetic resonance imaging (MRI)-based, high-resolution, numerical model of the head of a healthy human subject. In order to formulate the model, we performed quantitative volumetric segmentation on the human head, using T1-weighted MRI. The high spatial resolution used (1 × 1 × 1 mm3), allowed for the precise computation and visualization of a higher number of anatomical structures than provided by previous models. Furthermore, the high spatial resolution allowed us to study individual thin anatomical structures of clinical relevance not visible by the standard model currently adopted in computational bioelectromagnetics. When we computed the electromagnetic field and specific absorption rate (SAR) at 7 Tesla MRI using this high-resolution model, we were able to obtain a detailed visualization of such fine anatomical structures as the epidermis/dermis, bone structures, bone-marrow, white matter and nasal and eye structures. PMID:18985401

  2. Computing interaural differences through finite element modeling of idealized human heads.

    PubMed

    Cai, Tingli; Rakerd, Brad; Hartmann, William M

    2015-09-01

    Acoustical interaural differences were computed for a succession of idealized shapes approximating the human head-related anatomy: sphere, ellipsoid, and ellipsoid with neck and torso. Calculations were done as a function of frequency (100-2500 Hz) and for source azimuths from 10 to 90 degrees using finite element models. The computations were compared to free-field measurements made with a manikin. Compared to a spherical head, the ellipsoid produced greater large-scale variation with frequency in both interaural time differences and interaural level differences, resulting in better agreement with the measurements. Adding a torso, represented either as a large plate or as a rectangular box below the neck, further improved the agreement by adding smaller-scale frequency variation. The comparisons permitted conjectures about the relationship between details of interaural differences and gross features of the human anatomy, such as the height of the head, and length of the neck.

  3. Does littoral sand bypass the head of Mugu Submarine Canyon? - a modeling study

    USGS Publications Warehouse

    Xu, Jingping; Elias, Edwin; Kinsman, Nicole; Wang, Ping; Rosati, Julie D.; Roberts, Tiffany M.

    2011-01-01

    A newly developed sand-tracer code for the process-based model Delft3D (Deltares, The Netherlands) was used to simulate the littoral transport near the head of the Mugu Submarine Canyon in California, USA. For westerly swells, which account for more than 90% of the wave conditions in the region, the sand tracers in the downcoast littoral drift were unable to bypass the canyon head. A flow convergence near the upcoast rim of the canyon intercepts the tracers and moves them either offshore onto the shelf just west of the canyon rim (low wave height conditions) or into the canyon head (storm wave conditions). This finding supports the notion that Mugu Canyon is the true terminus of the Santa Barbara Littoral Cell.

  4. A link-segment model of upright human posture for analysis of head-trunk coordination

    NASA Technical Reports Server (NTRS)

    Nicholas, S. C.; Doxey-Gasway, D. D.; Paloski, W. H.

    1998-01-01

    Sensory-motor control of upright human posture may be organized in a top-down fashion such that certain head-trunk coordination strategies are employed to optimize visual and/or vestibular sensory inputs. Previous quantitative models of the biomechanics of human posture control have examined the simple case of ankle sway strategy, in which an inverted pendulum model is used, and the somewhat more complicated case of hip sway strategy, in which multisegment, articulated models are used. While these models can be used to quantify the gross dynamics of posture control, they are not sufficiently detailed to analyze head-trunk coordination strategies that may be crucial to understanding its underlying mechanisms. In this paper, we present a biomechanical model of upright human posture that extends an existing four mass, sagittal plane, link-segment model to a five mass model including an independent head link. The new model was developed to analyze segmental body movements during dynamic posturography experiments in order to study head-trunk coordination strategies and their influence on sensory inputs to balance control. It was designed specifically to analyze data collected on the EquiTest (NeuroCom International, Clackamas, OR) computerized dynamic posturography system, where the task of maintaining postural equilibrium may be challenged under conditions in which the visual surround, support surface, or both are in motion. The performance of the model was tested by comparing its estimated ground reaction forces to those measured directly by support surface force transducers. We conclude that this model will be a valuable analytical tool in the search for mechanisms of balance control.

  5. Quantitative Simulations of MST Visual Receptive Field Properties Using a Template Model of Heading Estimation

    NASA Technical Reports Server (NTRS)

    Stone, Leland S.; Perrone, J. A.

    1997-01-01

    We previously developed a template model of primate visual self-motion processing that proposes a specific set of projections from MT-like local motion sensors onto output units to estimate heading and relative depth from optic flow. At the time, we showed that that the model output units have emergent properties similar to those of MSTd neurons, although there was little physiological evidence to test the model more directly. We have now systematically examined the properties of the model using stimulus paradigms used by others in recent single-unit studies of MST: 1) 2-D bell-shaped heading tuning. Most MSTd neurons and model output units show bell-shaped heading tuning. Furthermore, we found that most model output units and the finely-sampled example neuron in the Duffy-Wurtz study are well fit by a 2D gaussian (sigma approx. 35deg, r approx. 0.9). The bandwidth of model and real units can explain why Lappe et al. found apparent sigmoidal tuning using a restricted range of stimuli (+/-40deg). 2) Spiral Tuning and Invariance. Graziano et al. found that many MST neurons appear tuned to a specific combination of rotation and expansion (spiral flow) and that this tuning changes little for approx. 10deg shifts in stimulus placement. Simulations of model output units under the same conditions quantitatively replicate this result. We conclude that a template architecture may underlie MT inputs to MST.

  6. Markov Chain Model-Based Optimal Cluster Heads Selection for Wireless Sensor Networks

    PubMed Central

    Ahmed, Gulnaz; Zou, Jianhua; Zhao, Xi; Sadiq Fareed, Mian Muhammad

    2017-01-01

    The longer network lifetime of Wireless Sensor Networks (WSNs) is a goal which is directly related to energy consumption. This energy consumption issue becomes more challenging when the energy load is not properly distributed in the sensing area. The hierarchal clustering architecture is the best choice for these kind of issues. In this paper, we introduce a novel clustering protocol called Markov chain model-based optimal cluster heads (MOCHs) selection for WSNs. In our proposed model, we introduce a simple strategy for the optimal number of cluster heads selection to overcome the problem of uneven energy distribution in the network. The attractiveness of our model is that the BS controls the number of cluster heads while the cluster heads control the cluster members in each cluster in such a restricted manner that a uniform and even load is ensured in each cluster. We perform an extensive range of simulation using five quality measures, namely: the lifetime of the network, stable and unstable region in the lifetime of the network, throughput of the network, the number of cluster heads in the network, and the transmission time of the network to analyze the proposed model. We compare MOCHs against Sleep-awake Energy Efficient Distributed (SEED) clustering, Artificial Bee Colony (ABC), Zone Based Routing (ZBR), and Centralized Energy Efficient Clustering (CEEC) using the above-discussed quality metrics and found that the lifetime of the proposed model is almost 1095, 2630, 3599, and 2045 rounds (time steps) greater than SEED, ABC, ZBR, and CEEC, respectively. The obtained results demonstrate that the MOCHs is better than SEED, ABC, ZBR, and CEEC in terms of energy efficiency and the network throughput. PMID:28241492

  7. Markov Chain Model-Based Optimal Cluster Heads Selection for Wireless Sensor Networks.

    PubMed

    Ahmed, Gulnaz; Zou, Jianhua; Zhao, Xi; Sadiq Fareed, Mian Muhammad

    2017-02-23

    The longer network lifetime of Wireless Sensor Networks (WSNs) is a goal which is directly related to energy consumption. This energy consumption issue becomes more challenging when the energy load is not properly distributed in the sensing area. The hierarchal clustering architecture is the best choice for these kind of issues. In this paper, we introduce a novel clustering protocol called Markov chain model-based optimal cluster heads (MOCHs) selection for WSNs. In our proposed model, we introduce a simple strategy for the optimal number of cluster heads selection to overcome the problem of uneven energy distribution in the network. The attractiveness of our model is that the BS controls the number of cluster heads while the cluster heads control the cluster members in each cluster in such a restricted manner that a uniform and even load is ensured in each cluster. We perform an extensive range of simulation using five quality measures, namely: the lifetime of the network, stable and unstable region in the lifetime of the network, throughput of the network, the number of cluster heads in the network, and the transmission time of the network to analyze the proposed model. We compare MOCHs against Sleep-awake Energy Efficient Distributed (SEED) clustering, Artificial Bee Colony (ABC), Zone Based Routing (ZBR), and Centralized Energy Efficient Clustering (CEEC) using the above-discussed quality metrics and found that the lifetime of the proposed model is almost 1095, 2630, 3599, and 2045 rounds (time steps) greater than SEED, ABC, ZBR, and CEEC, respectively. The obtained results demonstrate that the MOCHs is better than SEED, ABC, ZBR, and CEEC in terms of energy efficiency and the network throughput.

  8. Kinematic Model-Based Pedestrian Dead Reckoning for Heading Correction and Lower Body Motion Tracking

    PubMed Central

    Lee, Min Su; Ju, Hojin; Song, Jin Woo; Park, Chan Gook

    2015-01-01

    In this paper, we present a method for finding the enhanced heading and position of pedestrians by fusing the Zero velocity UPdaTe (ZUPT)-based pedestrian dead reckoning (PDR) and the kinematic constraints of the lower human body. ZUPT is a well known algorithm for PDR, and provides a sufficiently accurate position solution for short term periods, but it cannot guarantee a stable and reliable heading because it suffers from magnetic disturbance in determining heading angles, which degrades the overall position accuracy as time passes. The basic idea of the proposed algorithm is integrating the left and right foot positions obtained by ZUPTs with the heading and position information from an IMU mounted on the waist. To integrate this information, a kinematic model of the lower human body, which is calculated by using orientation sensors mounted on both thighs and calves, is adopted. We note that the position of the left and right feet cannot be apart because of the kinematic constraints of the body, so the kinematic model generates new measurements for the waist position. The Extended Kalman Filter (EKF) on the waist data that estimates and corrects error states uses these measurements and magnetic heading measurements, which enhances the heading accuracy. The updated position information is fed into the foot mounted sensors, and reupdate processes are performed to correct the position error of each foot. The proposed update-reupdate technique consequently ensures improved observability of error states and position accuracy. Moreover, the proposed method provides all the information about the lower human body, so that it can be applied more effectively to motion tracking. The effectiveness of the proposed algorithm is verified via experimental results, which show that a 1.25% Return Position Error (RPE) with respect to walking distance is achieved. PMID:26561814

  9. Kinematic Model-Based Pedestrian Dead Reckoning for Heading Correction and Lower Body Motion Tracking.

    PubMed

    Lee, Min Su; Ju, Hojin; Song, Jin Woo; Park, Chan Gook

    2015-11-06

    In this paper, we present a method for finding the enhanced heading and position of pedestrians by fusing the Zero velocity UPdaTe (ZUPT)-based pedestrian dead reckoning (PDR) and the kinematic constraints of the lower human body. ZUPT is a well known algorithm for PDR, and provides a sufficiently accurate position solution for short term periods, but it cannot guarantee a stable and reliable heading because it suffers from magnetic disturbance in determining heading angles, which degrades the overall position accuracy as time passes. The basic idea of the proposed algorithm is integrating the left and right foot positions obtained by ZUPTs with the heading and position information from an IMU mounted on the waist. To integrate this information, a kinematic model of the lower human body, which is calculated by using orientation sensors mounted on both thighs and calves, is adopted. We note that the position of the left and right feet cannot be apart because of the kinematic constraints of the body, so the kinematic model generates new measurements for the waist position. The Extended Kalman Filter (EKF) on the waist data that estimates and corrects error states uses these measurements and magnetic heading measurements, which enhances the heading accuracy. The updated position information is fed into the foot mounted sensors, and reupdate processes are performed to correct the position error of each foot. The proposed update-reupdate technique consequently ensures improved observability of error states and position accuracy. Moreover, the proposed method provides all the information about the lower human body, so that it can be applied more effectively to motion tracking. The effectiveness of the proposed algorithm is verified via experimental results, which show that a 1.25% Return Position Error (RPE) with respect to walking distance is achieved.

  10. Double Cluster Heads Model for Secure and Accurate Data Fusion in Wireless Sensor Networks

    PubMed Central

    Fu, Jun-Song; Liu, Yun

    2015-01-01

    Secure and accurate data fusion is an important issue in wireless sensor networks (WSNs) and has been extensively researched in the literature. In this paper, by combining clustering techniques, reputation and trust systems, and data fusion algorithms, we propose a novel cluster-based data fusion model called Double Cluster Heads Model (DCHM) for secure and accurate data fusion in WSNs. Different from traditional clustering models in WSNs, two cluster heads are selected after clustering for each cluster based on the reputation and trust system and they perform data fusion independently of each other. Then, the results are sent to the base station where the dissimilarity coefficient is computed. If the dissimilarity coefficient of the two data fusion results exceeds the threshold preset by the users, the cluster heads will be added to blacklist, and the cluster heads must be reelected by the sensor nodes in a cluster. Meanwhile, feedback is sent from the base station to the reputation and trust system, which can help us to identify and delete the compromised sensor nodes in time. Through a series of extensive simulations, we found that the DCHM performed very well in data fusion security and accuracy. PMID:25608211

  11. Does a Longer Delay in Fixation of Talus Fractures Cause Osteonecrosis?

    DTIC Science & Technology

    2011-01-01

    Does a Longer Delay in Fixation of Talus Fractures Cause Osteonecrosis ? CPT Jaime L. Bellamy, DO,1 CDR John J. Keeling, MD,2 Joseph Wenke, PhD,3 LTC...and development of osteonecrosis and posttraumatic arthritis. The Joint Theater Trauma Registry was queried by ICD-9 codes for talus fractures...Soldiers, ages 18 to 40, with talus fracture between 2001 and 2008 were included. Radiographs identified the injury type, Hawkins sign, osteonecrosis , and

  12. Modeling karst spring hydrograph recession based on head drop at sinkholes

    NASA Astrophysics Data System (ADS)

    Li, Guangquan; Goldscheider, Nico; Field, Malcolm S.

    2016-11-01

    Spring discharge often responds to rainfall with a rapid increase followed by a slower recession, and the mode of recession is often exponential-like. We propose a new model of the response of spring discharge to rainfall based on the square law for turbulent conduit flow. The new non-exponential model is compared against the exponential model under specific constraints. A hydrograph of St. Marks River in Florida is used to illustrate that when the change in ;sinkhole head; (defined as the hydraulic head at the upstream end of the karst conduit connected to the spring) is relatively small, the solution of the new model is close to that of the exponential model, which extends the validity and application of the exponential solution. When the change in sinkhole head is very large, the solutions from the two models clearly differ from each other. Limitations of the non-exponential model are analyzed by simulation of a hydrograph observed downstream of Wakulla Springs. It is concluded that both solutions are applicable when spring response is smaller than or comparable to the base flow, but are nonphysical when the response is much larger than the base discharge.

  13. Estimation of partial optical path length in the brain in subject-specific head models for near-infrared spectroscopy

    NASA Astrophysics Data System (ADS)

    Nakamura, Kotaro; Kurihara, Kazuki; Kawaguchi, Hiroshi; Obata, Takayuki; Ito, Hiroshi; Okada, Eiji

    2016-04-01

    Three-dimensional head models with the structures constructed from the MR head images of 40 volunteers were constructed to analyze light propagation in the subject-specific head models. The mean optical path length in the head and the partial optical path length in the brain at 13 fiducial points for each volunteer were estimated to evaluate the intersubject and spatial variability in the optical path lengths. Although the intersubject variability in the optical path lengths is very high, the spatial variability in the average of the mean optical path length and partial optical path length is similar to the previously reported data. The mean optical path length in the head increases, whereas the partial optical path length in the brain decreases with an increase in the depth of the brain surface. The partial optical path length is highly correlated with the depth of the brain surface in comparison to the mean optical path length in the head.

  14. Computational Modeling of the Working Process in the Combustion Chamber for Casing-Head Gas Recovery

    NASA Astrophysics Data System (ADS)

    Bachev, N. L.; Betinskaya, O. A.; Bul‧bovich, R. V.

    2016-01-01

    The present paper considers problems of computational modeling of the working process in multizone combustion chambers (CC) forming a part of gas-turbine power plants for recovering casing-head and other process gases. To investigate the turbulent flow and combustion, we use the LES method with a Smagorinskii subnet model. Various schemes of feeding components into combustion and dilution zones are considered. A comparison is made between the calculated and experimental data on the temperature in the combustion zone.

  15. OPG-Fc but Not Zoledronic Acid Discontinuation Reverses Osteonecrosis of the Jaws (ONJ) in Mice

    PubMed Central

    de Molon, Rafael Scaf; Shimamoto, Hiroaki; Bezouglaia, Olga; Pirih, Flavia Q; Dry, Sarah M; Kostenuik, Paul; Boyce, Rogely W; Dwyer, Denise; Aghaloo, Tara L; Tetradis, Sotirios

    2016-01-01

    Osteonecrosis of the jaws (ONJ) is a significant complication of antiresorptive medications, such as bisphosphonates and denosumab. Antiresorptive discontinuation to promote healing of ONJ lesions remains highly controversial and understudied. Here, we investigated whether antiresorptive discontinuation alters ONJ features in mice, employing the potent bisphosphonate zoledronic acid (ZA) or the receptor activator of NF-κB ligand (RANKL) inhibitor OPG-Fc, utilizing previously published ONJ animal models. Mice were treated with vehicle (veh), ZA, or OPG-Fc for 11 weeks to induce ONJ, and antiresorptives were discontinued for 6 or 10 weeks. Maxillae and mandibles were examined by µCT imaging and histologically. ONJ features in ZA and OPG-Fc groups included periosteal bone deposition, empty osteocyte lacunae, osteonecrotic areas, and bone exposure, each of which substantially resolved 10 weeks after discontinuing OPG-Fc but not ZA. Full recovery of tartrate-resistant acid phosphatase-positive (TRAP+) osteoclast numbers occurred after discontinuing OPG-Fc but not ZA. Our data provide the first experimental evidence demonstrating that discontinuation of a RANKL inhibitor, but not a bisphosphonate, reverses features of osteonecrosis in mice. It remains unclear whether antiresorptive discontinuation increases the risk of skeletal-related events in patients with bone metastases or fracture risk in osteoporosis patients, but these preclinical data may nonetheless help to inform discussions on the rationale for a “drug holiday” in managing the ONJ patient. PMID:25727550

  16. Periodontal Disease and Bisphosphonates Induce Osteonecrosis of the Jaws in the Rat

    PubMed Central

    Aghaloo, Tara L; Kang, Ben; Sung, Eric C; Shoff, Michael; Ronconi, Matthew; Gotcher, Jack E; Bezouglaia, Olga; Dry, Sarah M; Tetradis, Sotirios

    2012-01-01

    Bisphosphonates (BPs) are medications used commonly to treat primary and metastatic bone cancer, as well as osteoporosis. Although BPs improve bone mineral density, reduce fracture risk, and reduce hypercalcemia of malignancy, some patients develop BP-related osteonecrosis of the jaws (BRONJ). This devastating complication is defined as clinically exposed bone in the maxillofacial region for more than 8 weeks. Despite an increasing number of BRONJ cases since first reported, the disease pathophysiology remains largely unknown. Since published studies suggest a significant role for dental disease in the pathophysiology of BRONJ, we developed a BRONJ animal model where aggressive periodontal disease is induced by ligature placement around the crown of the right maxillary first molar in the presence of vehicle (veh) or zoledronic acid (ZA), a potent BP. Ligature placement induced significant alveolar bone loss, which was attenuated by ZA treatment. Osteonecrosis was observed associated with ligature-induced periodontitis in the ZA-treated group. This was seen as sequestration and extensive periosteal alveolar bone formation on micro–computed tomography (μCT) in the ligated site of BP-treated animals. Histologic examination confirmed these findings, seen as necrotic bone with diffuse loss of osteocytes and empty lacunae, rimming of the necrotic bone by squamous epithelium and inflammation, and exposure to the oral cavity. Importantly, the rat lesions were strikingly similar to those of BRONJ patients. Our data suggest that dental disease and potent BP therapy are sufficient for BRONJ development in the rat. PMID:21351151

  17. Realistic and spherical head modeling for EEG forward problem solution: a comparative cortex-based analysis.

    PubMed

    Vatta, Federica; Meneghini, Fabio; Esposito, Fabrizio; Mininel, Stefano; Di Salle, Francesco

    2010-01-01

    The accuracy of forward models for electroencephalography (EEG) partly depends on head tissues geometry and strongly affects the reliability of the source reconstruction process, but it is not yet clear which brain regions are more sensitive to the choice of different model geometry. In this paper we compare different spherical and realistic head modeling techniques in estimating EEG forward solutions from current dipole sources distributed on a standard cortical space reconstructed from Montreal Neurological Institute (MNI) MRI data. Computer simulations are presented for three different four-shell head models, two with realistic geometry, either surface-based (BEM) or volume-based (FDM), and the corresponding sensor-fitted spherical-shaped model. Point Spread Function (PSF) and Lead Field (LF) cross-correlation analyses were performed for 26 symmetric dipole sources to quantitatively assess models' accuracy in EEG source reconstruction. Realistic geometry turns out to be a relevant factor of improvement, particularly important when considering sources placed in the temporal or in the occipital cortex.

  18. Modeling Heart Rate Regulation—Part I: Sit-to-stand Versus Head-up Tilt

    PubMed Central

    Olufsen, Mette S.; Alston, April V.; Tran, Hien T.; Ottesen, Johnny T.; Novak, Vera

    2008-01-01

    In this study we describe a model predicting heart rate regulation during postural change from sitting to standing and during head-up tilt in five healthy elderly adults. The model uses blood pressure as an input to predict baroreflex firing-rate, which in turn is used to predict efferent parasympathetic and sympathetic outflows. The model also includes the combined effects of vestibular and central command stimulation of muscle sympathetic nerve activity, which is increased at the onset of postural change. Concentrations of acetylcholine and noradrenaline, predicted as functions of sympathetic and parasympathetic outflow, are then used to estimate the heart rate response. Dynamics of the heart rate and the baroreflex firing rate are modeled using a system of coupled ordinary delay differential equations with 17 parameters. We have derived sensitivity equations and ranked sensitivities of all parameters with respect to all state variables in our model. Using this model we show that during head-up tilt, the baseline firing-rate is larger than during sit-to-stand and that the combined effect of vestibular and central command stimulation of muscle sympathetic nerve activity is less pronounced during head-up tilt than during sit-to-stand. PMID:18064571

  19. Lane heading difference: An innovative model for drowsy driving detection using retrospective analysis around curves.

    PubMed

    Morris, Drew M; Pilcher, June J; Switzer, Fred S

    2015-07-01

    Driving while sleepy is a serious contributor to automobile accidents. Previous research has shown that drowsy drivers produce systematic errors (variability) in vehicle behavior which are detectable using vehicle monitoring technology. The current study developed a new methodological approach using a vehicle heading difference metric to detect drowsy driving more effectively than other more commonly used methods. Twenty participants completed a driving scenario as well as several measures of fatigue in five testing sessions across a night of sleep deprivation. Each simulated highway driving session lasted 20 min, and was analyzed for lateral lane position variability and vehicle heading difference variability with two statistical methods. Fatigue measures monitored reaction time, attention, and oculomotor movement. The results showed that examining lane heading difference using the absolute value of the raw data detected driving variability better across the night than other statistical models. The results from the fatigue measures indicated an increase in reaction time and response lapses, as well as a decrease in oculomotor reactivity across the night. These results suggest that in fatigued drivers the statistical model using the absolute value of lane heading could be an improved metric for drowsy driving detection that could accurately detect detriments in driving ability at lower levels of fatigue.

  20. Osteochondral Autograft Transplantation Surgery for Metacarpal Head Defects.

    PubMed

    Kitay, Alison; Waters, Peter M; Bae, Donald S

    2016-03-01

    Post-traumatic osteonecrosis of the metacarpal head is a challenging problem, particularly in younger patients in whom arthroplasty may not be a durable option. Although several osteochondral reconstructive options have been proposed, some are associated with considerable donor site morbidity and/or require the use of internal fixation. We present an application of osteochondral autograft transplantation surgery as a treatment option for focal metacarpal head lesions. An osteochondral plug from the non-weight-bearing articular surface of the knee is transferred and press-fit to resurface a focal metacarpal head defect. The technical pearls and pitfalls are reviewed, and an illustrative case is presented.

  1. Rapidly re-computable EEG (electroencephalography) forward models for realistic head shapes

    SciTech Connect

    Ermer, J. J.; Mosher, J. C.; Baillet, S.; Leahy, R. M.

    2001-01-01

    Solution of the EEG source localization (inverse) problem utilizing model-based methods typically requires a significant number of forward model evaluations. For subspace based inverse methods like MUSIC [6], the total number of forward model evaluations can often approach an order of 10{sup 3} or 10{sup 4}. Techniques based on least-squares minimization may require significantly more evaluations. The observed set of measurements over an M-sensor array is often expressed as a linear forward spatio-temporal model of the form: F = GQ + N (1) where the observed forward field F (M-sensors x N-time samples) can be expressed in terms of the forward model G, a set of dipole moment(s) Q (3xP-dipoles x N-time samples) and additive noise N. Because of their simplicity, ease of computation, and relatively good accuracy, multi-layer spherical models [7] (or fast approximations described in [1], [7]) have traditionally been the 'forward model of choice' for approximating the human head. However, approximation of the human head via a spherical model does have several key drawbacks. By its very shape, the use of a spherical model distorts the true distribution of passive currents in the skull cavity. Spherical models also require that the sensor positions be projected onto the fitted sphere (Fig. 1), resulting in a distortion of the true sensor-dipole spatial geometry (and ultimately the computed surface potential). The use of a single 'best-fitted' sphere has the added drawback of incomplete coverage of the inner skull region, often ignoring areas such as the frontal cortex. In practice, this problem is typically countered by fitting additional sphere(s) to those region(s) not covered by the primary sphere. The use of these additional spheres results in added complication to the forward model. Using high-resolution spatial information obtained via X-ray CT or MR imaging, a realistic head model can be formed by tessellating the head into a set of contiguous regions (typically the

  2. A mouse model of weight-drop closed head injury: emphasis on cognitive and neurological deficiency

    PubMed Central

    Khalin, Igor; Jamari, Nor Laili Azua; Razak, Nadiawati Bt Abdul; Hasain, Zubaidah Bt; Nor, Mohd Asri bin Mohd; Zainudin, Mohd Hakimi bin Ahmad; Omar, Ainsah Bt; Alyautdin, Renad

    2016-01-01

    Traumatic brain injury (TBI) is a leading cause of death and disability in individuals worldwide. Producing a clinically relevant TBI model in small-sized animals remains fairly challenging. For good screening of potential therapeutics, which are effective in the treatment of TBI, animal models of TBI should be established and standardized. In this study, we established mouse models of closed head injury using the Shohami weight-drop method with some modifications concerning cognitive deficiency assessment and provided a detailed description of the severe TBI animal model. We found that 250 g falling weight from 2 cm height produced severe closed head injury in C57BL/6 male mice. Cognitive disorders in mice with severe closed head injury could be detected using passive avoidance test on day 7 after injury. Findings from this study indicate that weight-drop injury animal models are suitable for further screening of brain neuroprotectants and potentially are similar to those seen in human TBI. PMID:27212925

  3. Impact of head modeling and sensor types in localizing human gamma-band oscillations.

    PubMed

    Mideksa, K G; Hoogenboom, N; Hellriegel, H; Krause, H; Schnitzler, A; Deuschl, G; Raethjen, J; Heute, U; Muthuraman, M

    2014-01-01

    An effective mechanism in neuronal communication is oscillatory neuronal synchronization. The neuronal gamma-band (30-100 Hz) synchronization is associated with attention which is induced by a certain visual stimuli. Numerous studies have shown that the gamma-band activity is observed in the visual cortex. However, impact of different head modeling techniques and sensor types to localize gamma-band activity have not yet been reported. To do this, the brain activity was recorded using 306 magnetoencephalography (MEG) sensors, consisting of 102 magnetometers and 102 pairs of planar gradiometers (one measuring the derivative of the magnetic field along the latitude and the other along the longitude), and the data were analyzed with respect to time, frequency, and location of the strongest response. The spherical head models with a single-shell and overlapping spheres (local sphere) have been used as a forward model for calculating the external magnetic fields generated from the gamma-band activity. For each sensor type, the subject-specific frequency range of the gamma-band activity was obtained from the spectral analysis. The identified frequency range of interest with the highest gamma-band activity is then localized using a spatial-filtering technique known as dynamic imaging of coherent sources (DICS). The source analysis for all the subjects revealed that the gradiometer sensors which measure the derivative along the longitude, showed sources close to the visual cortex (cuneus) as compared to the other gradiometer sensors which measure the derivative along the latitude. However, using the magnetometer sensors, it was not possible to localize the sources in the region of interest. When comparing the two head models, the local-sphere model helps in localizing the source more focally as compared to the single-shell head model.

  4. Analysis of head-down tilt as an analog of weightlessness using a methematical simulation model

    NASA Technical Reports Server (NTRS)

    Leonard, J. I.

    1984-01-01

    Antiorthostasis or head down tilt of a moderate degree was used as a ground based analog of weightless space flight to study headward fluid shifts, decreased plasma volume, orthostatic intolerance and muscular skeletal degradation. A mathematical model was used to help interpret these observations. The model proved most valuable for these studies was originally developed as a description of the major circulatory, fluid and electrolyte control systems. Two different experimental studies are employed to validate the model. The first is a 24 hour head down tilt study and the second is a 7 day head down bed rest study. The major issues addressed include the reduction in plasma volume, the dynamic changes of venous pressure and cardiac output, the extent of central hypervolemia during long term zero g exposure, the existence of an early diuresis, the mechanisms which alter the renal regulating hormones during the short term and long term periods, the significance of potassium loss on other zero g responses, and the role of transcapillary filtration in adjusting fluid shifts. The use of mathematical models as an interpretive and analysis technique for experimental research for space life science is illustrated.

  5. Mapping the brain cortex using an analytical model of the head

    NASA Astrophysics Data System (ADS)

    Hollaender, Igor

    1995-04-01

    In neurosciences, 3D renderings of the human brain cortex based on MR tomographical measurements are often used to study cortical structures, their similarity or variability, or to depict surface distribution of a given physical quantity. We have developed a method for producing maps of the human cortex depicting the complete brain surface in one view. The mapping is based on casting rays normal to the skin surface of the head. The projection surface is then remapped to the plane. An analytical model of the head consisting of four Bezier patches is used for generating the normal rays. The contribution describes the structure of the model and its computation, the projection geometry of the mapping, and the details of the rendering phase. Examples of possible applications of the method are presented.

  6. Lamb’s head: The model for novice education in endoscopic sinus surgery

    PubMed Central

    Skitarelić, Neven; Mladina, Ranko

    2015-01-01

    Structured training in endonasal endoscopic sinus surgery (EESS) and skull base surgery is essential considering serious potential complications. We have developed a detailed concept on training these surgical skills on the lamb’s head. This simple and extremely cheap model offers the possibility of training even more demanding and advanced procedures in human endonasal endoscopic surgery such as: frontal sinus surgery, orbital decompression, cerebrospinal fluid-leak repair followed also by the naso-septal flap, etc. Unfortunately, the sphenoid sinus surgery cannot be practiced since quadrupeds do not have this sinus. Still, despite this anatomical limitation, it seems that the lamb’s head can be very useful even for the surgeons already practicing EESS, but in a limited edition because of a lack of the experience and dexterity. Only after gaining the essential surgical skills of this demanding field it makes sense to go for the expensive trainings on the human cadaveric model. PMID:26413487

  7. A multi-tissue segmentation of the human head for detailed computational models.

    PubMed

    Hannula, Markus; Narra, Nathaniel; Onnela, Niina; Dastidar, Prasun; Hyttinen, Jari

    2014-01-01

    This paper describes the creation of an anatomically detailed high resolution model of the human head based on the Visible Human Female data from the National Library of Medicine archives. Automatic and semi-automatic segmentation algorithms were applied over the 3 image volumes – CT, MRI and anatomical cryo-sections of the cadaver – to label a total of 23 tissues. The results were combined to create a labeled volume of the head with voxel dimensions of 0.33×0.33×0.33 mm. The individual label matrices and their corresponding surface meshes are made available to be used freely. The detailed blood vessel network and ocular tissues will be of interest in computational modelling and simulation studies.

  8. Sunitinib related osteonecrosis of jaw: a case report.

    PubMed

    Fleissig, Yoram; Regev, Eran; Lehman, Hadas

    2012-03-01

    A 58-year-old woman presented to the Oral and Maxillofacial Surgery Clinic experiencing severe limited mouth opening and exposed bone in the socket of the right mandibular third molar 8 months following the extraction of the tooth. The patient had been treated during the year before her presentation with sunitinib, an antiangiogenic drug, for renal cell carcinoma. The clinical, radiographic, and histologic picture of a chronic nonhealing extraction socket was consistent with osteonecrosis of the jaw (ONJ), although she had never been treated with bisphosphonates or corticosteroids. The treatment with sunitinib was discontinued and the patient was treated with antibiotics and physiotherapy for 12 weeks with complete recovery. Sunitinib may cause osteonecrosis of the jaw after oral surgical interventions with no previous exposure to bisphosphonates. The pathogenesis may be related to its antiangiogenic mechanism and impaired wound healing. Full recovery may require long-term cessation of the insulting drug combined with prolonged antibiotic treatment.

  9. Parallel computation of the SAR distribution in a 3D human head model

    NASA Astrophysics Data System (ADS)

    Walendziuk, Wojciech

    2008-01-01

    This work presents a way of parallel computation of the Specific Absorption Rate distribution. The parallel program used in the computation was based on the FDTD (Finite-Difference Time-Domain) method [1,2,3]. In order to establish communication among the computational nodes, the MPI (Message Passing Interface) standard was used [4,5,6]. The presented example of a human head numerical model was built with the use of MRI (Magnetic Resonance Image) pictures.

  10. Dynamic modeling of the neck muscles during horizontal head movement. Part II: Model construction in Pro/Engineer.

    PubMed

    Haapala, Stephenie A; Enderle, John D

    2003-01-01

    This paper describes the next phase of research on a parametric model of the head-neck system for dynamic simulation of horizontal head rotation. A skull has been imported into Pro/Engineer software and has been assigned mass properties such as density, surface area and moments of inertia. The origin of a universal coordinate system has been located at the center of gravity of the T1 vertebrae. Identification of this origin allows insertion and attachment points of the sternocleidomastoid (SCOM) and splenius capitis to be located. An assembly has been created, marking the location of both muscle sets. This paper will also explore the obstacles encountered when working with an imported feature in Pro/E and attempts to resolve some of these issues. The goal of this work involves the creation of a 3D homeomorphic saccadic eye and head movement system.

  11. Progressive Diffuse Osteonecrosis in a Patient with Secondary Hemophagocytic Lymphohistiocytosis

    PubMed Central

    Takahashi, Takashi; Rykken, Jeffrey

    2015-01-01

    This is a case report with serial imaging showing progression of diffuse osteonecrosis in a patient after a diagnosis of secondary hemophagocytic lymphohistiocytosis (HLH). While bone marrow involvement in HLH has been long noted at histological evaluation and is itself one of the diagnosis criteria, to the best of our knowledge, there has been no previous publication addressing osseous image findings in a patient with HLH. PMID:26693376

  12. Modeling and Optimization of Airbag Helmets for Preventing Head Injuries in Bicycling.

    PubMed

    Kurt, Mehmet; Laksari, Kaveh; Kuo, Calvin; Grant, Gerald A; Camarillo, David B

    2017-04-01

    Bicycling is the leading cause of sports-related traumatic brain injury. Most of the current bike helmets are made of expanded polystyrene (EPS) foam and ultimately designed to prevent blunt trauma, e.g., skull fracture. However, these helmets have limited effectiveness in preventing brain injuries. With the availability of high-rate micro-electrical-mechanical systems sensors and high energy density batteries, a new class of helmets, i.e., expandable helmets, can sense an impending collision and expand to protect the head. By allowing softer liner medium and larger helmet sizes, this novel approach in helmet design provides the opportunity to achieve much lower acceleration levels during collision and may reduce the risk of brain injury. In this study, we first develop theoretical frameworks to investigate impact dynamics of current EPS helmets and airbag helmets-as a form of expandable helmet design. We compared our theoretical models with anthropomorphic test dummy drop test experiments. Peak accelerations obtained from these experiments with airbag helmets achieve up to an 8-fold reduction in the risk of concussion compared to standard EPS helmets. Furthermore, we construct an optimization framework for airbag helmets to minimize concussion and severe head injury risks at different impact velocities, while avoiding excessive deformation and bottoming-out. An optimized airbag helmet with 0.12 m thickness at 72 ± 8 kPa reduces the head injury criterion (HIC) value to 190 ± 25 at 6.2 m/s head impact velocity compared to a HIC of 1300 with a standard EPS helmet. Based on a correlation with previously reported HIC values in the literature, this airbag helmet design substantially reduces the risks of severe head injury up to 9 m/s.

  13. Numerical model (switchable/dual model) of the human head for rigid body and finite elements applications.

    PubMed

    Tabacu, Stefan

    2015-01-01

    In this paper, a methodology for the development and validation of a numerical model of the human head using generic procedures is presented. All steps required, starting with the model generation, model validation and applications will be discussed. The proposed model may be considered as a dual one due to its capabilities to switch from deformable to a rigid body according to the application's requirements. The first step is to generate the numerical model of the human head using geometry files or medical images. The required stiffness and damping for the elastic connection used for the rigid body model are identified by performing a natural frequency analysis. The presented applications for model validation are related to impact analysis. The first case is related to Nahum's (Nahum and Smith 1970) experiments pressure data being evaluated and a pressure map generated using the results from discrete elements. For the second case, the relative displacement between the brain and the skull is evaluated according to Hardy's (Hardy WH, Foster CD, Mason, MJ, Yang KH, King A, Tashman S. 2001.Investigation of head injury mechanisms using neutral density technology and high-speed biplanar X-ray. Stapp Car Crash J. 45:337-368, SAE Paper 2001-22-0016) experiments. The main objective is to validate the rigid model as a quick and versatile tool for acquiring the input data for specific brain analyses.

  14. Spontaneous osteonecrosis of the knee. Treatment and evolution.

    PubMed

    Valentí Nín, J R; Leyes, M; Schweitzer, D

    1998-01-01

    We performed a retrospective study on 21 patients affected by unilateral spontaneous osteonecrosis of the femoral condyle. Fifteen were women and 6 men. Their average age was 66.9 years. In ten cases the onset of pain was sudden, with a clear previous history of trauma in two of them. Gait pain, effusion, and joint locking were the most frequent clinical symptoms. At the time of diagnosis, 7 patients presented with grade I necrosis, 8 grade II, 1 grade III, and 5 grade IV, following Koshino's classification [11]. The average percentage of osteonecrosis was 36.8%. Six patients underwent conservative treatment with physical exercises and nonsteroidal anti-inflammatory drugs. We performed arthroscopy alone in 4 patients, arthroscopy and drilling in 8, valgus high tibial osteotomy in 2, and total knee arthroplasty in 1. The overall results after an average follow-up 41 months were excellent and good in 76.2% of the cases, fair in 14.3%, and poor in 9.5%. An associated medial meniscus tear was found in half of the patients who underwent surgery. In patients diagnosed with grade III and IV osteonecrosis, no increase in the percentage of necrosis was observed.

  15. Osteonecrosis of both knees in a woman with Crohn's disease

    PubMed Central

    Barbosa, Mara; Cotter, José

    2016-01-01

    Osteonecrosis is a very rare complication of Crohn’s disease (CD). It is not clear if it is related to corticosteroid therapy or if it occurs as an extraintestinal manifestation of inflammatory bowel disease. We present the case of a patient with CD who presented with osteonecrosis of both knees. A 22 years old woman was diagnosed with CD in April 2012 (Montreal Classification A2L1 + L4B3p). She was started on prednisolone (40 mg/d), azathioprine (100 mg/d) and messalazine (3 g/d). In July 2012, due to active perianal disease, infliximab therapy was initiated. In September 2012, she had a pelvic abscess complicated by peritonitis and an ileal segmental resection and right hemicolectomy were performed. In December 2012 she was diagnosed with bilateral septic arthritis of both knees with walking impairment. She was treated with amoxicillin-clavulanic acid, started a physical rehabilitation program and progressively improved. However, then, bilateral knee pain exacerbated by movement developed. Magnetic resonance imaging showed multiple osseous medullary infarcts in the distal extremity of the femurs, proximal extremity of the tibiae and patellas and no signs of subchondral collapse, which is consistent with osteonecrosis. The patient recovered completely and maintains therapy with azathioprine and messalazine. A review of the literature is also done. PMID:27867692

  16. Dental extraction following zoledronate, induces osteonecrosis in rat´s jaw

    PubMed Central

    Gómez-Clavel, José-Francisco; Gaitán-Cepeda, Luis-Alberto

    2017-01-01

    Background Bisphosphonate-Related Osteonecrosis of the Jaw (BRONJ) is clinically characterized by the presence of exposed bone in the oral cavity that persists for more than eight weeks. Previous attempts to establish an animal model have not sufficiently considered disease features. Our aim was to establish an inexpensive and replicable animal model that develops BRONJ in a short time. Material and Methods Thirty-two male Wistar rats were randomly divided into two groups: control and experimental. In the experimental group, we administered 0.06mg/kg intraperitoneal dose of zoledronic acid (ZA) 7 and 14 days prior to maxillary second molar extraction. At two, four and six weeks after tooth extraction, the animals were euthanized, and we dissected the maxilla following histological procedures. We stained serial slides with hematoxylin and eosin and Masson’s trichrome. The samples were harvested for macroscopic, radiologic and histological evaluation of bone changes. Results At two weeks postextraction, we observed exposed necrotic bone in dental socket areas in experimental groups. Radiological analysis revealed osteolytic lesions accompanied by extensive destruction and sequestrum formation in the same group. Histological examination confirmed the absence of necrotic bone in control groups in contrast with the experimental groups. The percentage of empty lacunae and the number of osteoclasts and the necrotic bone area were significantly increased (p<0.05) in the experimental groups. Conclusions The animal model using ZA administration to prior dental extraction successfully mimicked human BRONJ lesions. Also, the model was easily replicated, inexpensive and showed different features than other previous BRONJ models. Key words:Bisphosphonates, osteonecrosis, dental extractions, animal model, BRONJ. PMID:28160593

  17. Post-traumatic osteonecrosis of the lunate after fracture of the distal radius.

    PubMed

    Nakanishi, Akito; Yajima, Hiroshi; Kisanuki, Osamu

    2014-12-01

    We present a case of post-traumatic osteonecrosis of the lunate after fracture of the distal radius. Post-traumatic osteonecrosis of the carpal lunate after a fracture of the distal radius has, to our knowledge, not been reported previously. We treated the patient with vascularised bone graft from the distal radius, with a satisfactory result.

  18. Bilateral Maxillary Reconstruction Using Fibular Flap in Bisphosphonate-related Osteonecrosis

    PubMed Central

    Fujiwara, Toshihiro; Kawai, Kenichiro; Nishimoto, Soh; Kakibuchi, Masao

    2016-01-01

    Summary: Recent reports have shown successful transfer of vascularized fibular flap in bisphosphonate-induced mandibular osteonecrosis. We present a case of a 50-year-old patient who presented with bisphosphonate-related osteonecrosis of bilateral maxilla, which is reconstructed using a fibular flap. PMID:27757355

  19. Tooth exfoliation, osteonecrosis and neuralgia following herpes zoster of trigeminal nerve.

    PubMed

    Volvoikar, Preeti; Patil, Shama; Dinkar, Ajit

    2002-01-01

    A case of herpes zoster of the trigeminal nerve with complications of osteonecrosis and neuralgia in the absence of local or systemic predisposing factors is presented. The literature is reviewed and the role of varicella zoster virus in the pathology of tooth exfoliation and osteonecrosis is discussed.

  20. Gadopentetate-dimeglumine-enhanced MR imaging of osteonecrosis and osteochondritis dissecans of the elbow: initial experience.

    PubMed

    Peiss, J; Adam, G; Casser, R; Urhahn, R; Günther, R W

    1995-01-01

    Magnetic resonance imaging (MRI) was performed on seven patients with aseptic osteonecrosis (n = 4) and osteochondritis dissecans (OCD; n = 3) of the elbow. Precontrast MRI was superior to plain radiographs, which did not show any abnormality in three cases of osteonecrosis. On gadopentetate-dimeglumine-enhanced T1-weighted images, which were obtained in three patients with osteonecrosis and three patients with OCD, all cases of osteonecrosis demonstrated homogeneous enhancement of the lesions. All cases of OCD were diagnosed on plain radiographs. On MRI one showed significant enhancement of the loose body. In another case an incompletely enhancing loose body was surrounded by a diffusely enhancing region. In the third patient only a small marginal enhancement of the defect was observed. Our results suggest that MRI can improve the accuracy in diagnosis of aseptic osteonecrosis of the elbow. The use of gadopentetate dimeglumine allows the viability of the lesions or the loose bodies to be demonstrated and reparative tissue to be detected.

  1. Effects of D-003 on Lipopolysaccharides-induced Osteonecrosis in Rabbits.

    PubMed

    Noa, Miriam; Valle, M; Mendoza, Sarahí; Mas, Rosa; Mendoza, Nilda

    2011-09-01

    D-003, a mixture of high molecular weight acids, inhibits cholesterol synthesis prior to mevalonate and prevents osteoporosis induced by ovariectomy in rats, and both osteoporosis and osteonecrosis induced by corticoids in rats. The aim of this study was to investigate effects of D-003 on lipopolysaccharides-induced osteonecrosis in rabbits. Animals were randomized into 5 groups: a sham and four groups injected with lipopolysaccharides: one treated orally with vehicle and three with D-003 (5, 25 and 200 mg/kg, respectively) during four weeks. We assessed the effects of treatments on the incidence of osteonecrosis (number of animals with osteonecrosis lesions/animals per group), the mean numbers and areas of osteonecrosis per animal and on the mean sizes of the bone marrow fat cells. The incidence of osteonecrosis in the groups of D-003 25 and 200 mg/kg was significantly lower than in the positive controls. The reduction of osteonecrosis increased with the doses, but significant dose-dependence relationship was not achieved. D-003 significantly and dose-dependently decreased the number of osteonecrosis lesions per animal as compared to the positive controls. Likewise, the mean osteonecrosis areas in the proximal femoral and humeral bones were significantly decreased by D-003. The injection of lipopolysaccharides significantly increased the average size of bone marrow fat cells as compared to the negative controls, and such increase was significantly and markedly reduced with D-003. It is concluded that D-003 reduced the incidence, number and percent areas of osteonecrosis lesions, and the size of bone marrow fat cells, a marker of adipogenesis, in rabbits with lipopolysaccharides-induced ostenonecrosis.

  2. Angiography, scintigraphy, intraosseous pressure, and histologic findings in high-risk osteonecrotic femoral heads with negative magnetic resonance images.

    PubMed

    Koo, K H; Kim, R; Cho, S H; Song, H R; Lee, G; Ko, G H

    1994-11-01

    One hundred twenty-six hips of 68 patients who were suspected of having osteonecrosis or being at risk for osteonecrosis were studied with magnetic resonance (MR) imaging. Abnormal patterns on MR imaging characteristic of osteonecrosis were observed in 98 hips. The remaining 28 hips (22 patients) with negative MR images underwent superselective angiography of the medial femoral circumflex artery. Angiography showed interruption of the superior retinacular arteries in 13 hips (12 patients), including 6 of 7 symptomatic hips. Bone scans were performed on 8 of 13 hips angiographically positive for osteonecrosis. Decrease of radionuclide uptake (cold lesions) was observed in all 8 of these femoral heads. Thirteen femoral heads with interruption of superior retinacular arteries underwent intraosseous pressure measurement and core biopsy. Intraosseous pressure was elevated in 11 hips. The results of histologic study showed evidence of early necrosis in 10 femoral heads. This study indicates that there are a considerable number of femoral heads at high risk, even when they have negative MR images. They do, however, show positive findings on angiography, scintigraphy (cold lesions), intraosseous pressure measurement, and histologic study.

  3. Stereoscopic vascular models of the head and neck: A computed tomography angiography visualization.

    PubMed

    Cui, Dongmei; Lynch, James C; Smith, Andrew D; Wilson, Timothy D; Lehman, Michael N

    2016-01-01

    Computer-assisted 3D models are used in some medical and allied health science schools; however, they are often limited to online use and 2D flat screen-based imaging. Few schools take advantage of 3D stereoscopic learning tools in anatomy education and clinically relevant anatomical variations when teaching anatomy. A new approach to teaching anatomy includes use of computed tomography angiography (CTA) images of the head and neck to create clinically relevant 3D stereoscopic virtual models. These high resolution images of the arteries can be used in unique and innovative ways to create 3D virtual models of the vasculature as a tool for teaching anatomy. Blood vessel 3D models are presented stereoscopically in a virtual reality environment, can be rotated 360° in all axes, and magnified according to need. In addition, flexible views of internal structures are possible. Images are displayed in a stereoscopic mode, and students view images in a small theater-like classroom while wearing polarized 3D glasses. Reconstructed 3D models enable students to visualize vascular structures with clinically relevant anatomical variations in the head and neck and appreciate spatial relationships among the blood vessels, the skull and the skin.

  4. Neuropathological changes in a lamb model of non-accidental head injury (the shaken baby syndrome).

    PubMed

    Finnie, J W; Blumbergs, P C; Manavis, J; Turner, R J; Helps, S; Vink, R; Byard, R W; Chidlow, G; Sandoz, B; Dutschke, J; Anderson, R W G

    2012-08-01

    Non-accidental head injury (NAHI), also termed the "shaken baby syndrome", is a major cause of death and severe neurological dysfunction in children under three years of age, but it is debated whether shaking alone is sufficient to produce brain injury and mortality or whether an additional head impact is required. In an attempt to resolve this question, we used a lamb model of NAHI since these animals have a relatively large gyrencephalic brain and weak neck muscles resembling those of a human infant. Three anaesthetised lambs of lower body weight than others in the experimental group died unexpectedly after being shaken, proving that shaking alone can be lethal. In these lambs, axonal injury, neuronal reaction and albumin extravasation were widely distributed in the hemispheric white matter, brainstem and at the craniocervical junction, and of much greater magnitude than in higher body weight lambs which did not die. Moreover, in the eyes of these shaken lambs, there was damage to retinal inner nuclear layer neurons, mild, patchy ganglion cell axonal injury, widespread Muller glial reaction, and uveal albumin extravasation. This study proved that shaking of a subset of lambs can result in death, without an additional head impact being required.

  5. The dependence of EM energy absorption upon human head modeling at 900 MHz

    SciTech Connect

    Hombach, V.; Kuehn, E.; Meier, K.; Burkhardt, M.; Kuster, N.

    1996-10-01

    In this paper the dependence of electromagnetic energy absorption at 900 MHz in the human head on its anatomy and its modeling are investigated for RF-sources operating in the very close proximity of the head. Different numerical head phantoms based on MRI scans of three different adults were used with voxel sizes down to 1 mm{sup 3}. Simulations of the absorption were performed by distinguishing the electrical properties of up to 13 tissue types. In addition simulations with modified electric parameters and reduced degrees of complexity were performed. Thus, the phantoms greatly differ from each other in terms of shape, size, and internal anatomy. The numerical results are compared with those of measurements in a multitissue phantom and two homogeneous phantoms of different shapes and sizes. The results demonstrate that size and shape are of minor importance. Although local SAR values depend significantly on local inhomogeneities and electric properties, the volume-averaged spatial peak SAR obtained with the homogeneous phantoms only slightly overestimates that of the worst-case exposure in the inhomogeneous phantoms.

  6. Neonatal EEG at scalp is focal and implies high skull conductivity in realistic neonatal head models.

    PubMed

    Odabaee, Maryam; Tokariev, Anton; Layeghy, Siamak; Mesbah, Mostefa; Colditz, Paul B; Ramon, Ceon; Vanhatalo, Sampsa

    2014-08-01

    The potential improvements in spatial resolution of neonatal EEG used in source localization have been challenged by the insufficiencies in realistic neonatal head models. Our present study aimed at using empirical methods to indirectly estimate skull conductivity; the model parameter that is known to significantly affect the behavior of newborn scalp EEG and cause it to be markedly different from that of an adult. To this end, we used 64 channel EEG recordings to study the spatial specificity of scalp EEG by assessing the spatial decays in focal transients using both amplitudes and between-c'hannels linear correlations. The findings showed that these amplitudes and correlations decay within few centimeters from the reference channel/electrode, and that the nature of the decay is independent of the scalp area. This decay in newborn infants was found to be approximately three times faster than the corresponding decay in adult EEG analyzed from a set of 256 channel recordings. We then generated realistic head models using both finite and boundary element methods along with a manually segmented magnetic resonance images to study the spatial decays of scalp potentials produced by single dipole in the cortex. By comparing the spatial decays due to real and simulated EEG for different skull conductivities (from 0.003 to 0.3S/m), we showed that a close match between the empirical and simulated decays was obtained when the selected skull conductivity for newborn was around 0.06-0.2S/m. This is over an order of magnitude higher than the currently used values in adult head modeling. The results also showed that the neonatal scalp EEG is less smeared than that of an adult and this characteristic is the same across the entire scalp, including the fontanel region. These results indicate that a focal cortical activity is generally only registered by electrodes within few centimeters from the source. Hence, the conventional 10 to 20 channel neonatal EEG acquisition systems give a

  7. Biomechanical models for vibration feedthrough to hands and head for a semisupine pilot.

    PubMed

    Jex, H R; Magdaleno, R E

    1978-01-01

    A series of tracking experiments under vibration has been carried out on the AMRL/BBV shaker facilities covering three axes of vibration with sinusoidal and random waveforms and different control stick configurations. Based on this and other data, a lumped-parameter biomechanical model has been evolved to suit the needs of aircraft control system designers for the new generation of low-altitude, high-speed bombers and highly maneuverable fighters. This paper shows that measured vibration feedthrough to hands and head can be adequately described by this model when linearized about the appropriate configuration of display, posture, and control. The model includes effects of: semisupine torso; sliding hip, plus rocking chest supported on a compliant buttocks/seat; head bobbing on an articulated neck; upper arm and forearm links plus grip-interface compliance, driven by an active neuromuscular system; elbow rest (optional); and stick "feel system" dynamics. Examples are given of the model's application to predict effects of: a 65 degrees semisupine seat, apparent impedance increase of a control stick under pilot control, and a sliding arm rest.

  8. Evaluation of three-dimensional anisotropic head model for mapping realistic electromagnetic fields of brain tissues

    NASA Astrophysics Data System (ADS)

    Jeong, Woo Chul; Wi, Hun; Sajib, Saurav Z. K.; Oh, Tong In; Kim, Hyung Joong; Kwon, Oh In; Woo, Eung Je

    2015-08-01

    Electromagnetic fields provide fundamental data for the imaging of electrical tissue properties, such as conductivity and permittivity, in recent magnetic resonance (MR)-based tissue property mapping. The induced voltage, current density, and magnetic flux density caused by externally injected current are critical factors for determining the image quality of electrical tissue conductivity. As a useful tool to identify bio-electromagnetic phenomena, precise approaches are required to understand the exact responses inside the human body subject to an injected currents. In this study, we provide the numerical simulation results of electromagnetic field mapping of brain tissues using a MR-based conductivity imaging method. First, we implemented a realistic three-dimensional human anisotropic head model using high-resolution anatomical and diffusion tensor MR images. The voltage, current density, and magnetic flux density of brain tissues were imaged by injecting 1 mA of current through pairs of electrodes on the surface of our head model. The current density map of anisotropic brain tissues was calculated from the measured magnetic flux density based on the linear relationship between the water diffusion tensor and the electrical conductivity tensor. Comparing the current density to the previous isotropic model, the anisotropic model clearly showed the differences between the brain tissues. This originates from the enhanced signals by the inherent conductivity contrast as well as the actual tissue condition resulting from the injected currents.

  9. Cortical imaging on a head template: a simulation study using a resistor mesh model (RMM).

    PubMed

    Chauveau, Nicolas; Franceries, Xavier; Aubry, Florent; Celsis, Pierre; Rigaud, Bernard

    2008-09-01

    The T1 head template model used in Statistical Parametric Mapping Version 2000 (SPM2), was segmented into five layers (scalp, skull, CSF, grey and white matter) and implemented in 2 mm voxels. We designed a resistor mesh model (RMM), based on the finite volume method (FVM) to simulate the electrical properties of this head model along the three axes for each voxel. Then, we introduced four dipoles of high eccentricity (about 0.8) in this RMM, separately and simultaneously, to compute the potentials for two sets of conductivities. We used the direct cortical imaging technique (CIT) to recover the simulated dipoles, using 60 or 107 electrodes and with or without addition of Gaussian white noise (GWN). The use of realistic conductivities gave better CIT results than standard conductivities, lowering the blurring effect on scalp potentials and displaying more accurate position areas when CIT was applied to single dipoles. Simultaneous dipoles were less accurately localized, but good qualitative and stable quantitative results were obtained up to 5% noise level for 107 electrodes and up to 10% noise level for 60 electrodes, showing that a compromise must be found to optimize both the number of electrodes and the noise level. With the RMM defined in 2 mm voxels, the standard 128-electrode cap and 5% noise appears to be the upper limit providing reliable source positions when direct CIT is used. The admittance matrix defining the RMM is easy to modify so as to adapt to different conductivities. The next step will be the adaptation of individual real head T2 images to the RMM template and the introduction of anisotropy using diffusion imaging (DI).

  10. Transient Inverse Calibration of a Facies-Based Groundwater Flow and Transport Model Using Contaminant Concentration and Hydraulic Head Data

    NASA Astrophysics Data System (ADS)

    Williams, M. D.; Thorne, P. D.; Bergeron, M. P.; Vermeul, V. R.; Ward, D. L.

    2006-12-01

    A three dimensional groundwater flow and transport model was calibrated against observations of both hydraulic head and tritium plume concentrations measured in wells. Hydraulic parameters were estimated with a transient inverse process using UCODE, a universal inverse modeling code developed jointly by the U.S. Geological Survey and the International Groundwater Modeling Center at the Colorado School of Mines. Previous groundwater models at the site had been calibrated using hydraulic head data in the transient inverse calibration process. The resulting models were good at fitting the hydraulic head data, but did not perform well in replicating the movement of contaminant plumes over this period. A separate transient inverse calibration effort used only tritium measurements collected from wells at the site over the operational period, along with estimates of the water volume and tritium mass discharged to the aquifer, to estimate the hydraulic properties. The resulting model did a better job of replicating the overall shape and development of the tritium plume, but did not do as well in matching the hydraulic heads. Both the hydraulic head and tritium concentration data sets were used jointly in the transient inverse process for this study. These data included 47,739 measurements of hydraulic head from 543 wells and 37,802 measurements of tritium concentrations from 1,201 wells. The transient inverse process estimated hydraulic conductivity for 18 facies-based zones in the main sand and gravel units in the unconfined aquifer. A simplified weighting scheme for the hydraulic head and tritium data was developed so that the overall sum-of-squared residuals for the inverse runs were roughly equally weighted for the two data sets. Preliminary simulation results from this combined calibration dataset show a good fit for both the evolving tritium plume and hydraulic head measurements over the operational period.

  11. Multifocal osteonecrosis in a patient with anamnestic ulcerative colitis. Is there a relationship with the disease and the use of glucocorticoids twenty years before? A brief review of the literature.

    PubMed

    Saviola, G; Abdi-Ali, L; Sacco, S; Dalle Carbonare, L G

    2016-01-01

    In 2013 a 40 year old man came to visit in our Rheumatology Unit because of a recent bilateral shoulder and hip pain. He had been treated from 1990 to 2000 with Cyclosporin A and Sulfasalazyn because of an ulcerative colitis which was completely in remission from 2000 . Glucocorticoids at the mean daily dose of 50 mg were administered only in the first period (1990-92). X-plain rays showed a suspicious multifocal osteonecrosis of both femoral and humeral heads. Magnetic Resonance confirmed the diagnosis (stage III and IV following Ficat and Arlet's criteria). The patient was treated with a cycle of hyperbaric oxygen therapy, with two cycles of intravenous clodronate and with a 2-month cycle of teriparatide. The treatment was able to save a sufficient function for both shoulders, while for both hips arthroplasty the surgery was required. The risks of osteonecrosis linked to inflammatory bowel diseases or to its therapy are discussed.

  12. 3-D diffusion tensor MRI anisotropy content-adaptive finite element head model generation for bioelectromagnetic imaging.

    PubMed

    Lee, W H; Kim, T S; Kim, Andrew T; Lee, S Y

    2008-01-01

    Realistic finite element (FE) head models have been successfully applied to bioelectromagnetic problems due to a realistic representation of arbitrary head geometry with inclusion of anisotropic material properties. In this paper, we propose a new automatic FE mesh generation scheme to generate a diffusion tensor MRI (DT-MRI) white matter anisotropy content-adaptive FE head model. We term this kind of mesh as wMesh. With this meshing technique, the anisotropic electrical conductivities derived from DT-MRIs can be best incorporated into the model. The influence of the white matter anisotropy on the EEG forward solutions has been studied via our wMesh head models. The scalp potentials computed from the anisotropic wMesh models against those of the isotropic models have been compared. The results describe that there are substantial changes in the scalp electrical potentials between the isotropic and anisotropic models, indicating that the inclusion of the white matter anisotropy is critical for accurate computation of E/MEG forward and inverse solutions. This fully automatic anisotropy-adaptive wMesh meshing scheme could be useful for modeling of individual-specific FE head models with better incorporation of the white matter anisotropic property towards bioelectromagnetic imaging.

  13. MIDA: A Multimodal Imaging-Based Detailed Anatomical Model of the Human Head and Neck

    PubMed Central

    Iacono, Maria Ida; Neufeld, Esra; Akinnagbe, Esther; Bower, Kelsey; Wolf, Johanna; Vogiatzis Oikonomidis, Ioannis; Sharma, Deepika; Lloyd, Bryn; Wilm, Bertram J.; Wyss, Michael; Pruessmann, Klaas P.; Jakab, Andras; Makris, Nikos; Cohen, Ethan D.; Kuster, Niels; Kainz, Wolfgang; Angelone, Leonardo M.

    2015-01-01

    Computational modeling and simulations are increasingly being used to complement experimental testing for analysis of safety and efficacy of medical devices. Multiple voxel- and surface-based whole- and partial-body models have been proposed in the literature, typically with spatial resolution in the range of 1–2 mm and with 10–50 different tissue types resolved. We have developed a multimodal imaging-based detailed anatomical model of the human head and neck, named “MIDA”. The model was obtained by integrating three different magnetic resonance imaging (MRI) modalities, the parameters of which were tailored to enhance the signals of specific tissues: i) structural T1- and T2-weighted MRIs; a specific heavily T2-weighted MRI slab with high nerve contrast optimized to enhance the structures of the ear and eye; ii) magnetic resonance angiography (MRA) data to image the vasculature, and iii) diffusion tensor imaging (DTI) to obtain information on anisotropy and fiber orientation. The unique multimodal high-resolution approach allowed resolving 153 structures, including several distinct muscles, bones and skull layers, arteries and veins, nerves, as well as salivary glands. The model offers also a detailed characterization of eyes, ears, and deep brain structures. A special automatic atlas-based segmentation procedure was adopted to include a detailed map of the nuclei of the thalamus and midbrain into the head model. The suitability of the model to simulations involving different numerical methods, discretization approaches, as well as DTI-based tensorial electrical conductivity, was examined in a case-study, in which the electric field was generated by transcranial alternating current stimulation. The voxel- and the surface-based versions of the models are freely available to the scientific community. PMID:25901747

  14. Minimum-norm cortical source estimation in layered head models is robust against skull conductivity error.

    PubMed

    Stenroos, Matti; Hauk, Olaf

    2013-11-01

    The conductivity profile of the head has a major effect on EEG signals, but unfortunately the conductivity for the most important compartment, skull, is only poorly known. In dipole modeling studies, errors in modeled skull conductivity have been considered to have a detrimental effect on EEG source estimation. However, as dipole models are very restrictive, those results cannot be generalized to other source estimation methods. In this work, we studied the sensitivity of EEG and combined MEG+EEG source estimation to errors in skull conductivity using a distributed source model and minimum-norm (MN) estimation. We used a MEG/EEG modeling set-up that reflected state-of-the-art practices of experimental research. Cortical surfaces were segmented and realistically-shaped three-layer anatomical head models were constructed, and forward models were built with Galerkin boundary element method while varying the skull conductivity. Lead-field topographies and MN spatial filter vectors were compared across conductivities, and the localization and spatial spread of the MN estimators were assessed using intuitive resolution metrics. The results showed that the MN estimator is robust against errors in skull conductivity: the conductivity had a moderate effect on amplitudes of lead fields and spatial filter vectors, but the effect on corresponding morphologies was small. The localization performance of the EEG or combined MEG+EEG MN estimator was only minimally affected by the conductivity error, while the spread of the estimate varied slightly. Thus, the uncertainty with respect to skull conductivity should not prevent researchers from applying minimum norm estimation to EEG or combined MEG+EEG data. Comparing our results to those obtained earlier with dipole models shows that general judgment on the performance of an imaging modality should not be based on analysis with one source estimation method only.

  15. MIDA: A Multimodal Imaging-Based Detailed Anatomical Model of the Human Head and Neck.

    PubMed

    Iacono, Maria Ida; Neufeld, Esra; Akinnagbe, Esther; Bower, Kelsey; Wolf, Johanna; Vogiatzis Oikonomidis, Ioannis; Sharma, Deepika; Lloyd, Bryn; Wilm, Bertram J; Wyss, Michael; Pruessmann, Klaas P; Jakab, Andras; Makris, Nikos; Cohen, Ethan D; Kuster, Niels; Kainz, Wolfgang; Angelone, Leonardo M

    2015-01-01

    Computational modeling and simulations are increasingly being used to complement experimental testing for analysis of safety and efficacy of medical devices. Multiple voxel- and surface-based whole- and partial-body models have been proposed in the literature, typically with spatial resolution in the range of 1-2 mm and with 10-50 different tissue types resolved. We have developed a multimodal imaging-based detailed anatomical model of the human head and neck, named "MIDA". The model was obtained by integrating three different magnetic resonance imaging (MRI) modalities, the parameters of which were tailored to enhance the signals of specific tissues: i) structural T1- and T2-weighted MRIs; a specific heavily T2-weighted MRI slab with high nerve contrast optimized to enhance the structures of the ear and eye; ii) magnetic resonance angiography (MRA) data to image the vasculature, and iii) diffusion tensor imaging (DTI) to obtain information on anisotropy and fiber orientation. The unique multimodal high-resolution approach allowed resolving 153 structures, including several distinct muscles, bones and skull layers, arteries and veins, nerves, as well as salivary glands. The model offers also a detailed characterization of eyes, ears, and deep brain structures. A special automatic atlas-based segmentation procedure was adopted to include a detailed map of the nuclei of the thalamus and midbrain into the head model. The suitability of the model to simulations involving different numerical methods, discretization approaches, as well as DTI-based tensorial electrical conductivity, was examined in a case-study, in which the electric field was generated by transcranial alternating current stimulation. The voxel- and the surface-based versions of the models are freely available to the scientific community.

  16. Clinical and image findings in bisphosphonate-related osteonecrosis of the jaws.

    PubMed

    Farias, Diogo Silva; Zen Filho, Edson Virgilio; de Oliveira, Thais Feitosa Leitão; Tinôco-Araújo, José Endrigo; Sampieri, Marcelo Bonifácio da Silva; Antunes, Heliton Spíndola; Santos, Paulo Sérgio da Silva

    2013-07-01

    Bisphosphonate-related osteonecrosis of the jaws (BRONJ) is characterized as exposed bone in the jaws for more than 8 weeks in patients with current or previous history of therapy with bisphosphonates (BPs) and no history of radiotherapy in the head and neck. We report a case series of 7 patients with BRONJ and analyze the variations of clinical and imaging signs, correlating them with the presence or absence of bone exposure. Among the patients, 6 were women and 1 was a man, aged 42-79 years. Five of the patients were using zoledronic acid and the other 2 alendronate. The use of BPs varied from 3 to 13 years. In 5 patients, tooth extraction was the triggering event of injuries. Panoramic radiographs and computed tomography (CT) were evaluated by a radiologist blinded to the cases. There were persistent unremodeled extraction socket even several months after tooth extraction in 3 of the cases that were consistent wit CT findings that also showed areas of osteosclerosis and osteolysis. Patients were treated according to the recommendations of the AAOMS, with surgical debridement and antibiotic coverage with amoxicillin in the symptomatic patients. The follow-up of these patients ranged from 8 to 34 months, with a good response to treatment. The image findings in this case series were not specific and showed no difference between each stages of BRONJ (AAOMS, 2009). The image features were similar in presence or absence of exposed bone.

  17. A genetic pedigree analysis to identify gene mutations involved in femoral head necrosis.

    PubMed

    Wang, Lin; Pan, Hehai; Zhu, Zhen-An

    2014-10-01

    The present study presents results from a linkage and mutation screening analysis aiming to identify the causative gene of femoral head necrosis, also known as osteonecrosis of femoral head (ONFH), in a Chinese pedigree. We collected clinical data on the osteonecrosis pedigree, and extracted blood and genomic DNA from the family members. Polymerase chain reaction (PCR) and direct sequencing allowed to identify a mutation in the COL2A1 gene of the proband; the clinical manifestations of the proband meet the criteria for osteonecrosis. The exons of COL2A1 were amplified by polymerase chain reaction and mutation screening was conducted by direct sequencing in all the family members. The locus was also sequenced in 50 unrelated healthy controls. The c.3665G>A heterozygous mutation was detected in patients of the pedigree, but not in healthy individuals. We conclude that a mutation in the COL2A1 gene is the causative agent of ONFH in this family. Therefore, this mutation may be associated with osteonecrosis in Chinese populations.

  18. An implanted spherical head model exposed to electromagnetic fields at a mobile communication frequency.

    PubMed

    Reyhani, S M S; Ludwig, Simone A

    2006-10-01

    Can cellular phones and personal communication systems base station antennas affect the active or passive implantable medical devices adversely? Concerns over the possible harmful effects of nonionizing irradiaton upon implanted medical devices have been present for many years. Key issues to address are the questions of whether mobile phones have a detrimental effect on implants, and how the interaction of the handset with the body can be minimized in order to both alleviate public fears and improve handset antenna performance and new implant designs. This paper presents a thorough investigation of the scattering of an electromagnetic (EM) wave from a perfectly conducting implant (a cylindrical wire and a very thin cylindrical disk) of electrically small radius (of resonant length), embedded eccentrically into a dielectric spherical head model by a dipole antenna (0.4 wavelength) at 900 MHz. The dyadic Green's function (DGF) for spherical vector wave functions is employed. Analytical expressions for the scattered fields of an implant embedded head model is obtained. Numerical results from analytical expressions are computed for this problem and then compared with the results from the same model using the finite-difference time-domain, EMU-FDTD electromagnetic simulator. Good agreement is observed between the analytical results on the proposed method in comparison with the FDTD method.

  19. Partially Automated Method for Localizing Standardized Acupuncture Points on the Heads of Digital Human Models

    PubMed Central

    Kim, Jungdae; Kang, Dae-In

    2015-01-01

    Having modernized imaging tools for precise positioning of acupuncture points over the human body where the traditional therapeutic method is applied is essential. For that reason, we suggest a more systematic positioning method that uses X-ray computer tomographic images to precisely position acupoints. Digital Korean human data were obtained to construct three-dimensional head-skin and skull surface models of six individuals. Depending on the method used to pinpoint the positions of the acupoints, every acupoint was classified into one of three types: anatomical points, proportional points, and morphological points. A computational algorithm and procedure were developed for partial automation of the positioning. The anatomical points were selected by using the structural characteristics of the skin surface and skull. The proportional points were calculated from the positions of the anatomical points. The morphological points were also calculated by using some control points related to the connections between the source and the target models. All the acupoints on the heads of the six individual were displayed on three-dimensional computer graphical image models. This method may be helpful for developing more accurate experimental designs and for providing more quantitative volumetric methods for performing analyses in acupuncture-related research. PMID:26101534

  20. Determination of stimulation focality in heterogeneous head models during transcranial magnetic stimulation (TMS)

    NASA Astrophysics Data System (ADS)

    Lee, Erik; Hadimani, Ravi; Jiles, David

    2015-03-01

    Transcranial Magnetic Stimulation (TMS) is an increasingly popular tool used by both the scientific and medical community to understand and treat the brain. TMS has the potential to help people with a wide range of diseases such as Parkinson's, Alzheimer's, and PTSD, while currently being used to treat people with chronic, drug-resistant depression. Through computer simulations, we are able to see the electric field that TMS induces in anatomical human models, but there is no measure to quantify this electric field in a way that relates to a specific patient undergoing TMS therapy. We propose a way to quantify the focality of the induced electric field in a heterogeneous head model during TMS by relating the surface area of the brain being stimulated to the total volume of the brain being stimulated. This figure would be obtained by conducting finite element analysis (FEA) simulations of TMS therapy on a patient specific head model. Using this figure to assist in TMS therapy will allow clinicians and researchers to more accurately stimulate the desired region of a patient's brain and be more equipped to do comparative studies on the effects of TMS across different patients. This work was funded by the Carver Charitable Trust.

  1. A new approach to calibrate steady groundwater flow models with time series of head observations

    NASA Astrophysics Data System (ADS)

    Obergfell, C.; Bakker, M.; Maas, C.

    2012-04-01

    We developed a new method to calibrate aquifer parameters of steady-state well field models using measured time series of head fluctuations. Our method is an alternative to standard pumping tests and is based on time series analysis using parametric impulse response functions. First, the pumping influence is isolated from the overall groundwater fluctuation observed at monitoring wells around the well field, and response functions are determined for each individual well. Time series parameters are optimized using a quasi-Newton algorithm. For one monitoring well, time series model parameters are also optimized by means of SCEM-UA, a Markov Chain Monte Carlo algorithm, as a control on the validity of the parameters obtained by the faster quasi-Newton method. Subsequently, the drawdown corresponding to an average yearly pumping rate is calculated from the response functions determined by time series analysis. The drawdown values estimated with acceptable confidence intervals are used as calibration targets of a steady groundwater flow model. A case study is presented of the drinking water supply well field of Waalwijk (Netherlands). In this case study, a uniform aquifer transmissivity is optimized together with the conductance of ditches in the vicinity of the well field. Groundwater recharge or boundary heads do not have to be entered, which eliminates two import sources of uncertainty. The method constitutes a cost-efficient alternative to pumping tests and allows the determination of pumping influences without changes in well field operation.

  2. CE-QUAL-W2 Modeling of Head-of-Reservoir Conditions at Shasta Reservoir, California

    NASA Astrophysics Data System (ADS)

    Clancey, K. M.; Saito, L.; Svoboda, C.; Bender, M. D.; Hannon, J.

    2014-12-01

    Restoration of Chinook salmon and steelhead is a priority in the Sacramento River Basin since they were listed under the Endangered Species Act in 1989 and 1998, respectively. Construction of Shasta Dam and Reservoir obstructed fish migration, resulting in severe population declines. Efforts have been undertaken to restore the fisheries, including evaluation of opportunities for reintroducing Chinook salmon upstream of the dam and providing juvenile fish passage downstream past Shasta Dam. Shasta Reservoir and the Sacramento River and McCloud River tributaries have been modeled with CE-QUAL-W2 (W2) to assess hydrodynamic and temperature conditions with and without surface curtains to be deployed in the tributaries. Expected head-of-reservoir tributary conditions of temperature and water depth are being simulated under dry, median and wet year conditions. Model output is analyzed during months of downstream migration of fish from upstream Sacramento and McCloud River tributaries. W2 will be used to determine presence of favorable conditions for juvenile rearing with proposed surface temperature curtains. Evaluation of favorable conditions for fish includes assessment of water temperature, velocities, and depth. Preliminary results for head-of-reservoir conditions and the influence of temperature curtains modeled with W2 will be presented. Study findings may assist in formulation of juvenile fish passage alternatives for Shasta Lake.

  3. Study of the influence of the laterality of mobile phone use on the SAR induced in two head models

    NASA Astrophysics Data System (ADS)

    Ghanmi, Amal; Varsier, Nadège; Hadjem, Abdelhamid; Conil, Emmanuelle; Picon, Odile; Wiart, Joe

    2013-05-01

    The objective of this paper is to investigate and to analyse the influence of the laterality of mobile phone use on the exposure of the brain to radio-frequencies (RF) and electromagnetic fields (EMF) from different mobile phone models using the finite-difference time-domain (FDTD) method. The study focuses on the comparison of the specific absorption rate (SAR) induced on the right and left sides of two numerical adult and child head models. The heads are exposed by both phone models operating in GSM frequency bands for both ipsilateral and contralateral configurations. A slight SAR difference between the two sides of the heads is noted. The results show that the variation between the left and the right sides is more important at 1800 MHz for an ipsilateral use. Indeed, at this frequency, the variation can even reach 20% for the SAR10g and the SAR1g induced in the head and in the brain, respectively. Moreover, the average SAR induced by the mobile phone in the half hemisphere of the brain in ipsilateral exposure is higher than in contralateral exposure. Owing to the superficial character of energy deposition at 1800 MHz, this difference in the SAR induced for the ipsilateral and contralateral usages is more significant at 1800 MHz than at 900 MHz. The results have shown that depending on the phantom head models, the SAR distribution in the brain can vary because of differences in anatomical proportions and in the geometry of the head models. The induced SAR in child head and in sub-regions of the brain is significantly higher (up to 30%) compared to the adult head. This paper confirms also that the shape/design of the mobile and the location of the antenna can have a large influence at high frequency on the exposure of the brain, particularly on the SAR distribution and on the distinguished brain regions.

  4. The risk of revision due to dislocation after total hip arthroplasty depends on surgical approach, femoral head size, sex, and primary diagnosis

    PubMed Central

    2012-01-01

    Background and purpose The effects of patient-related and technical factors on the risk of revision due to dislocation after primary total hip arthroplasty (THA) are only partly understood. We hypothesized that increasing the femoral head size can reduce this risk, that the lateral surgical approach is associated with a lower risk than the posterior and minimally invasive approaches, and that gender and diagnosis influence the risk of revision due to dislocation. Patients and methods Data on 78,098 THAs in 61,743 patients performed between 2005 and 2010 were extracted from the Swedish Hip Arthroplasty Register. Inclusion criteria were a head size of 22, 28, 32, or 36 mm, or the use of a dual-mobility cup. The covariates age, sex, primary diagnosis, type of surgical approach, and head size were entered into Cox proportional hazards models in order to calculate the adjusted relative risk (RR) of revision due to dislocation, with 95% confidence intervals (CI). Results After a mean follow-up of 2.7 (0–6) years, 399 hips (0.5%) had been revised due to dislocation. The use of 22-mm femoral heads resulted in a higher risk of revision than the use of 28-mm heads (RR = 2.0, CI: 1.2–3.3). Only 1 of 287 dual-mobility cups had been revised due to dislocation. Compared with the direct lateral approach, minimally invasive approaches were associated with a higher risk of revision due to dislocation (RR = 4.2, CI: 2.3–7.7), as were posterior approaches (RR = 1.3, CI: 1.1–1.7). An increased risk of revision due to dislocation was found for the diagnoses femoral neck fracture (RR = 3.9, CI: 3.1–5.0) and osteonecrosis of the femoral head (RR = 3.7, CI: 2.5–5.5), whereas women were at lower risk than men (RR = 0.8, CI: 0.7–1.0). Restriction of the analysis to the first 6 months after the index procedure gave similar risk estimates. Interpretation Patients with femoral neck fracture or osteonecrosis of the femoral head are at higher risk of dislocation. Use of the

  5. Coupled head neck torso and seat model for car seat optimization under rear-end impact

    NASA Astrophysics Data System (ADS)

    Bourdet, Nicolas; Willinger, Rémy

    2008-06-01

    The development of new protective systems must be performed on tools reliable and representative of alive human. In an earlier study, a simplified but realistic modelling of the head-neck system under moderate rear impact was performed. In order to address this issue, an original lumped model of the human torso was developed and coupled to a car seat-head rest complex. The experimental modal analysis of the human torso in a seating position performed by Kitazaki in 1992 [Paper presented at the United Kingdom Meeting on Human Response to Vibration held at I.S.V.R. University of Southampton, Southampton, UK, 28-30 September 1992.] was used in the present study for the identification of the mechanical parameters of a lumped human torso model. Despite its low complexity, this model was able to reproduce the five first experimental vibration modes and it was possible to validate it in terms of natural frequencies, damping ratio and mode shapes. In addition to the lumped approach, an external geometry of the human torso was implemented in order to provide a realistic coupling of the human body model to a finite element model of the car seat also developed in the present study. A parametric study was finally carried out in order to evaluate the influence of the torso behaviour and of the different parts of a car seat on the mechanical neck response under rear-end impact. The results of this study allow concluding that the torso behaviour has an important influence on the neck loading and therefore that the quality of a car seat depends on the human body substitute used. For instance, with the proposed torso model, a low-neck injury criterion (NIC) rearward value was obtained with low rigidity of the backrest foam and a stiff backrest net.

  6. Biofidelic white matter heterogeneity decreases computational model predictions of white matter strains during rapid head rotations.

    PubMed

    Maltese, Matthew R; Margulies, Susan S

    2016-11-01

    The finite element (FE) brain model is used increasingly as a design tool for developing technology to mitigate traumatic brain injury. We developed an ultra high-definition FE brain model (>4 million elements) from CT and MRI scans of a 2-month-old pre-adolescent piglet brain, and simulated rapid head rotations. Strain distributions in the thalamus, coronal radiata, corpus callosum, cerebral cortex gray matter, brainstem and cerebellum were evaluated to determine the influence of employing homogeneous brain moduli, or distinct experimentally derived gray and white matter property representations, where some white matter regions are stiffer and others less stiff than gray matter. We find that constitutive heterogeneity significantly lowers white matter deformations in all regions compared with homogeneous properties, and should be incorporated in FE model injury prediction.

  7. Effect of Cerebrospinal Fluid Modelling on Spherically Convergent Shear Waves during Blunt Head Trauma.

    PubMed

    Madhukar, Amit; Chen, Ying; Ostoja-Starzewski, Martin

    2017-03-14

    The MRI-based computational model, previously validated by tagged MRI and HARP imaging analysis technique on in vivo human brain deformation, is employed to study transient wave dynamics during blunt head trauma. Three different constitutive models are used for the cerebrospinal fluid (CSF): incompressible solid elastic, viscoelastic and fluid-like elastic using an equation of state model. Three impact cases are simulated which indicate that the blunt impacts give rise not only to a fast pressure wave but also to a slow, and potentially much more damaging, shear (distortional) wave that converges spherically towards the brain center. The wave amplification due to spherical geometry is balanced by damping due to tissues' viscoelasticity and the heterogeneous brain structure, suggesting a stochastic competition of these two opposite effects. It is observed that this convergent shear wave is dependent on the constitutive property of the CSF whereas the peak pressure is not as significantly affected.

  8. Osteonecrosis of the jaw in patient with denosumab therapy.

    PubMed

    Olate, Sergio; Uribe, Francisca; Martinez, Felipe; Almeida, Andrés; Unibazo, Alejandro

    2014-01-01

    Osteonecrosis (ON) of the jaw has previously been linked to the use of biphosphonates; however, new drugs, also shown similar conditions. This article presents a female patient with mandibular ON related to the use of denosumab. The 55-year-old presented with bone exposure with 8 months of evolution after a dental extraction. The patient began subcutaneous injections of 60 mg denosumab four months prior to the extraction and the lesion remained after the procedure. The patient, with 14 months of follow-up, show mandible ON with no favorable evolution. The clinical condition is presented and the literature of ON associated with denosumab is discussed.

  9. Antiresorptive drug-related osteonecrosis of the jaw.

    PubMed

    Uyanne, Jettie; Calhoun, Colonya C; Le, Anh D

    2014-04-01

    Nitrogen-containing and non-nitrogen-containing bisphosphonates have been implicated in the development of osteonecrosis of the jaw (ONJ), a condition termed bisphosphonate-related OHJ. Other antiresorptive drugs have been implicated in the development of OHJ, hence the new term antiresorptive drug-related ONJ. The underlying pathogenesis remains unclear, and no definite diagnosis or cure has been established for this debilitating condition. This article reviews some of the most common antiresorptive drugs with their associated risks of ONJ and the current understanding of the pathogenesis ONJ, and summarizes current clinical guidelines.

  10. Potential pathophysiological mechanisms in osteonecrosis of the jaw

    PubMed Central

    Landesberg, Regina; Woo, Victoria; Cremers, Serge; Cozin, Matthew; Marolt, Darja; Vunjak-Novakovic, Gordana; Kousteni, Stavroula; Raghavan, Srikala

    2015-01-01

    Bisphosphonates are used in the treatment of hypercalcemia of malignancy, skeletal complications associated with metastastic bone disease, Paget’s disease, and osteoporosis. Osteonecrosis of the jaw (ONJ) is a recently described clinical condition that has been associated with the use of nitrogen-containing bisphosphonates. Reports describing this entity first appeared in the literature in 2003. While there have been significant numbers of case reports and a limited number of retrospective and prospective studies examining risk factors associated with ONJ, the pathophysiology of this condition remains elusive. In this review, we explore proposed mechanisms underlying ONJ development and identify potential areas for future investigation. PMID:21291478

  11. Monte Carlo modeling of light propagation in the human head for applications in sinus imaging

    NASA Astrophysics Data System (ADS)

    Cerussi, Albert E.; Mishra, Nikhil; You, Joon; Bhandarkar, Naveen; Wong, Brian J. F.

    2015-02-01

    Sinus blockages are a common reason for physician visits, affecting 1 out of 7 in the United States. Over 20 million cases of acute bacterial sinusitis become chronic and require medical treatment. Diagnosis in the primary care setting is challenging because symptom criteria (via detailed clinical history) plus objective imaging (CT or endoscopy) is recommended. Unfortunately, neither option is routinely available in primary care. Our previous work demonstrated that low-cost near infrared (NIR) transillumination instruments produced signals that correlated with the bulk findings of sinus opacity measured by CT. We have upgraded the technology, but questions remain such as finding the optimal arrangement of light sources, measuring the influence of specific anatomical structures, and determining detection limits. In order to begin addressing these questions, we have modeled NIR light propagation inside the adult human head using a mesh-based Monte Carlo algorithm (MMCLab) applied to a detailed anatomical head model constructed from CT images. In this application the sinus itself, which under healthy conditions is a void region (e.g., non-scattering), is the region of interest instead of an obstacle to other contrast mechanisms. We report preliminary simulations that characterize the changes in detected intensity due to clear (i.e., healthy) versus blocked sinuses. We also ran simulations for two of our clinical cases and compared results with the measurements. The simulations presented herein serve as a proof of concept that this approach could be used to understand contrast mechanisms and limitations of NIR imaging of the sinus cavities.

  12. Safety and efficacy of quadrapeutics versus chemoradiation in head and neck carcinoma xenograft model

    PubMed Central

    Lukianova-Hleb, Ekaterina Y; Kim, Yoo-Shin; Aryasomayajula, Bhawani; Boulikas, Teni; Phan, Jack; Hung, Mien-Chie; Torchilin, Vladimir P; O’Neill, Brian E; Lapotko, Dmitri O

    2015-01-01

    Chemoradiation is the strongest anti-tumor therapy but in resistant unresectable cancers it often lacks safety and efficacy. We compared our recently developed cell-level combination approach, quadrapeutics, to chemoradiation therapy to establish pre-clinical data for its biodistribution, safety and efficacy in head and neck squamous cell carcinoma (HNSCC), as a clinically challenging aggressive and resistant cancer. In vitro and in vivo models of four carcinomas were treated with standard chemoradiation and quadrapeutics using identical drug and radiation doses. We applied liposomal cisplatin or doxorubicin, colloidal gold, near-infrared laser pulses and radiation, all at low safe doses. The final evaluation used a xenograft model of HNSCC. Quadrapeutics enhanced standard chemoradiation in vitro by reducing head and neck cancer cell proliferation by 1000-fold, inhibiting tumor growth in vivo by 34-fold and improving animal survival by 5-fold, and reducing the side effects to a negligible level. In quadrapeutics, we observed an “inversion” of the drug efficacy of two standard drugs: doxorubicin, a low efficacy drug for the cancers studied, was two times more efficient than cisplatin, the first choice drug in clinic for HNSCC. The radical therapeutic gain of quadrapeutics resulted from the intracellular synergy of the four components employed which we administered in a specific sequence, while the reduction in the toxicity was due to the low doses of all four components. The biodistribution, safety and efficacy data for quadrapeutics in HNSCC ensure its high translational potential and justify the possibility of clinical trials. PMID:26885444

  13. An Unusual Case of Osteonecrosis of Jaw associated with Dengue fever and Periodontitis.

    PubMed

    Indurkar, Maya S; Sethi, Rohan

    2015-02-01

    Osteonecrosis is a disorder occurring rarely in the jaw. Dengue fever is a common mosquito-borne disease prevalent in many countries including India. The following report presents an interesting case of maxillary osteonecrosis in a middle aged male with history of dengue infection. We also diagnosed symptoms of chronic periodontitis in the patient, which may have potentiated the necrosis. This case report will describe a novel clinical presentation and management of osteonecrosis of jaw (ONJ) of unknown origin and a possible pathogenesis explaining the association of ONJ with dengue fever and periodontitis. This article is protected by copyright. All rights reserved.

  14. The Role of Antiangiogenic Therapy in the Development of Osteonecrosis of the Jaw.

    PubMed

    Fantasia, John E

    2015-11-01

    There is an increasing use of established and newer medications that have antiangiogenic properties. Inhibition of angiogenesis likely has either a primary or secondary role in the development of osteonecrosis of the jaw (ONJ). These medications are being used in the treatment of various cancers and in the treatment of several non-oncologic conditions. Antiangiogenic medications when used in combination with antiresorptive medications, such as nitrogen-containing bisphosphonates or denosumab, seem to increase the likelihood of osteonecrosis of the jaw. This review highlights the role of inhibitors of angiogenesis and their role in the development of osteonecrosis of the jaws.

  15. [Etiologic diagnosis of jaw osteonecrosis, other than bisphosphonate and radiotherapy related osteitis].

    PubMed

    Magremanne, M; Picheca, S; Reychler, H

    2014-02-01

    Our purpose was to highlight the various etiologies of maxillo-mandibular osteonecrosis, other than radiotherapy and biphosphonate related osteitis that have been abundantly reported. We performed a PubMed search from August 1, 1972 to August 1, 2012 using the following MeSH terms: "osteonecrosis", "bone", "necrosis", "jaw", "maxilla", "mandible", "palate", "oral", "avascular necrosis", NOT "bisphosphonate" NOT "osteoradionecrosis". Most cases of osteonecrosis were iatrogenic. Viral, mycotic, or bacterial infections were less frequent causes. Cocaine abuse, Wegener's granulomatosis, and N/K lymphoma were other etiologies. It is important to identify the various etiologies rapidly to manage this sometimes very mutilating condition adequately.

  16. Development of the software tool for generation and visualization of the finite element head model with bone conduction sounds

    NASA Astrophysics Data System (ADS)

    Nikolić, Dalibor; Milošević, Žarko; Saveljić, Igor; Filipović, Nenad

    2015-12-01

    Vibration of the skull causes a hearing sensation. We call it Bone Conduction (BC) sound. There are several investigations about transmission properties of bone conducted sound. The aim of this study was to develop a software tool for easy generation of the finite element (FE) model of the human head with different materials based on human head anatomy and to calculate sound conduction through the head. Developed software tool generates a model in a few steps. The first step is to do segmentation of CT medical images (DICOM) and to generate a surface mesh files (STL). Each STL file presents a different layer of human head with different material properties (brain, CSF, different layers of the skull bone, skin, etc.). The next steps are to make tetrahedral mesh from obtained STL files, to define FE model boundary conditions and to solve FE equations. This tool uses PAK solver, which is the open source software implemented in SIFEM FP7 project, for calculations of the head vibration. Purpose of this tool is to show impact of the bone conduction sound of the head on the hearing system and to estimate matching of obtained results with experimental measurements.

  17. Multistate Models for Estimation of Survival and Reproduction in the Grey-headed Albatross (Thalassarche chrysostoma)

    USGS Publications Warehouse

    Converse, Sarah J.; Kendall, William L.; Doherty, Paul F.; Ryan, Peter G.

    2009-01-01

    Reliable information on demography is necessary for conservation of albatrosses, the most threatened family of pelagic birds. Albatross survival has been estimated using mark?recapture data and the Cormack-Jolly-Seber (CJS) model. However, albatross exhibit skipped breeding, violating assumptions of the CJS model. Multistate modeling integrating unobservable states is a promising tool for such situations. We applied multistate models to data on Grey-headed Albatross (Thalassarche chrysostoma) to evaluate model performance and describe demographic patterns. These included a multistate equivalent of the CJS model (MS-2), including successful and failed breeding states and ignoring temporary emigration, and three versions of a four-state multistate model that accounts for temporary emigration by integrating unobservable states: a model (MS-4) with one sample per breeding season, a robust design model (RDMS-4) with multiple samples per season and geographic closure within the season, and an open robust design model (ORDMS-4) with multiple samples per season and staggered entry and exit of animals within the season. Survival estimates from the MS-2 model were higher than those from the MS-4 model, which resulted in apparent percent relative bias averaging 2.2%. The ORDMS-4 model was more appropriate than the RDMS-4 model, given that staggered entry and exit occurred. Annual survival probability for Greyheaded Albatross at Marion Island was 0.951 ? 0.006 (SE), and the probability of skipped breeding in a subsequent year averaged 0.938 for successful and 0.163 for failed breeders. We recommend that multistate models with unobservable states, combined with robust-design sampling, be used in studies of species that exhibit temporary emigration.

  18. Experimental study of blast-induced traumatic brain injury using a physical head model.

    PubMed

    Zhang, Jiangyue; Pintar, Frank A; Yoganandan, Narayan; Gennarelli, Thomas A; Son, Steven F

    2009-11-01

    This study was conducted to quantify intracranial biomechanical responses and external blast overpressures using physical head model to understand the biomechanics of blast traumatic brain injury and to provide experimental data for computer simulation of blast-induced brain trauma. Ellipsoidal-shaped physical head models, made from 3-mm polycarbonate shell filled with Sylgard 527 silicon gel, were used. Six blast tests were conducted in frontal, side, and 45 degrees oblique orientations. External blast overpressures and internal pressures were quantified with ballistic pressure sensors. Blast overpressures, ranging from 129.5 kPa to 769.3 kPa, were generated using a rigid cannon and 1.3 to 3.0 grams of pentaerythritol tetranitrate (PETN) plastic sheet explosive (explosive yield of 13.24 kJ and TNT equivalent mass of 2.87 grams for 3 grams of material). The PETN plastic sheet explosive consisted of 63% PETN powder, 29% plasticizer, and 8% nitrocellulose with a density of 1.48 g/cm3 and detonation velocity of 6.8 km/s. Propagation and reflection of the shockwave was captured using a shadowgraph technique. Shockwave speeds ranging from 423.3 m/s to 680.3 m/s were recorded. The model demonstrated a two-stage response: a pressure dominant (overpressure) stage followed by kinematic dominant (blast wind) stage. Positive pressures in the brain simulant ranged from 75.1 kPa to 1095 kPa, and negative pressures ranged from -43.6 kPa to -646.0 kPa. High- and normal-speed videos did not reveal observable deformations in the brain simulant from the neutral density markers embedded in the midsagittal plane of the head model. Amplitudes of the internal positive and negative pressures were found to linearly correlate with external overpressure. Results from the current study suggested a pressure-dominant brain injury mechanism instead of strain injury mechanism under the blast severity of the current study. These quantitative results also served as the validation and calibration

  19. Anatomical Reproducibility of a Head Model Molded by a Three-dimensional Printer.

    PubMed

    Kondo, Kosuke; Nemoto, Masaaki; Masuda, Hiroyuki; Okonogi, Shinichi; Nomoto, Jun; Harada, Naoyuki; Sugo, Nobuo; Miyazaki, Chikao

    2015-01-01

    We prepared rapid prototyping models of heads with unruptured cerebral aneurysm based on image data of computed tomography angiography (CTA) using a three-dimensional (3D) printer. The objective of this study was to evaluate the anatomical reproducibility and accuracy of these models by comparison with the CTA images on a monitor. The subjects were 22 patients with unruptured cerebral aneurysm who underwent preoperative CTA. Reproducibility of the microsurgical anatomy of skull bone and arteries, the length and thickness of the main arteries, and the size of cerebral aneurysm were compared between the CTA image and rapid prototyping model. The microsurgical anatomy and arteries were favorably reproduced, apart from a few minute regions, in the rapid prototyping models. No significant difference was noted in the measured lengths of the main arteries between the CTA image and rapid prototyping model, but errors were noted in their thickness (p < 0.001). A significant difference was also noted in the longitudinal diameter of the cerebral aneurysm (p < 0.01). Regarding the CTA image as the gold standard, reproducibility of the microsurgical anatomy of skull bone and main arteries was favorable in the rapid prototyping models prepared using a 3D printer. It was concluded that these models are useful tools for neurosurgical simulation. The thickness of the main arteries and size of cerebral aneurysm should be comprehensively judged including other neuroimaging in consideration of errors.

  20. Anatomical Reproducibility of a Head Model Molded by a Three-dimensional Printer

    PubMed Central

    KONDO, Kosuke; NEMOTO, Masaaki; MASUDA, Hiroyuki; OKONOGI, Shinichi; NOMOTO, Jun; HARADA, Naoyuki; SUGO, Nobuo; MIYAZAKI, Chikao

    We prepared rapid prototyping models of heads with unruptured cerebral aneurysm based on image data of computed tomography angiography (CTA) using a three-dimensional (3D) printer. The objective of this study was to evaluate the anatomical reproducibility and accuracy of these models by comparison with the CTA images on a monitor. The subjects were 22 patients with unruptured cerebral aneurysm who underwent preoperative CTA. Reproducibility of the microsurgical anatomy of skull bone and arteries, the length and thickness of the main arteries, and the size of cerebral aneurysm were compared between the CTA image and rapid prototyping model. The microsurgical anatomy and arteries were favorably reproduced, apart from a few minute regions, in the rapid prototyping models. No significant difference was noted in the measured lengths of the main arteries between the CTA image and rapid prototyping model, but errors were noted in their thickness (p < 0.001). A significant difference was also noted in the longitudinal diameter of the cerebral aneurysm (p < 0.01). Regarding the CTA image as the gold standard, reproducibility of the microsurgical anatomy of skull bone and main arteries was favorable in the rapid prototyping models prepared using a 3D printer. It was concluded that these models are useful tools for neurosurgical simulation. The thickness of the main arteries and size of cerebral aneurysm should be comprehensively judged including other neuroimaging in consideration of errors. PMID:26119896

  1. MRI-Based Multiscale Model for Electromagnetic Analysis in the Human Head with Implanted DBS

    PubMed Central

    Iacono, Maria Ida; Makris, Nikos; Mainardi, Luca; Angelone, Leonardo M.; Bonmassar, Giorgio

    2013-01-01

    Deep brain stimulation (DBS) is an established procedure for the treatment of movement and affective disorders. Patients with DBS may benefit from magnetic resonance imaging (MRI) to evaluate injuries or comorbidities. However, the MRI radio-frequency (RF) energy may cause excessive tissue heating particularly near the electrode. This paper studies how the accuracy of numerical modeling of the RF field inside a DBS patient varies with spatial resolution and corresponding anatomical detail of the volume surrounding the electrodes. A multiscale model (MS) was created by an atlas-based segmentation using a 1 mm3 head model (mRes) refined in the basal ganglia by a 200 μm2 ex-vivo dataset. Four DBS electrodes targeting the left globus pallidus internus were modeled. Electromagnetic simulations at 128 MHz showed that the peak of the electric field of the MS doubled (18.7 kV/m versus 9.33 kV/m) and shifted 6.4 mm compared to the mRes model. Additionally, the MS had a sixfold increase over the mRes model in peak-specific absorption rate (SAR of 43.9 kW/kg versus 7 kW/kg). The results suggest that submillimetric resolution and improved anatomical detail in the model may increase the accuracy of computed electric field and local SAR around the tip of the implant. PMID:23956789

  2. Osteonecrosis of the jaw associated with ziv-aflibercept

    PubMed Central

    Enzinger, Peter; McCleary, Nadine; Manon, Reshma; Villa, Alessandro; Treister, Nathaniel; Woo, Sook-Bin

    2016-01-01

    Medication-related osteonecrosis of the jaw (MRONJ) has been associated with medications that include bisphosphonates (BPs), denosumab, bevacizumab and sunitinib. Ziv-aflibercept is a recombinant human vascular endothelial growth factor (VEGF) receptor which has been used to treat patients with various advanced solid tumors. We report three patients without a history of the use of medications known to cause MRONJ presenting with jaw osteonecrosis typical for MRONJ following therapy with ziv-aflibercept. All patients had metastatic gastrointestinal cancer treated with ziv-aflibercept and were evaluated for MRONJ because of exposed bone in the oral cavity. None of the patients had received antiresorptive therapies or any other medication known to cause MRONJ, and none had received radiation therapy to the jaws. Patients were aged 43, 51, 63 and all were males. Patients received 7, 16 and 23 cycles of ziv-aflibercept treatment and developed necrotic bone. All three patients presented with mandibular involvement, with two reporting pain. Patients were managed with anti-microbial mouth rinse, antibiotics and non-surgical sequestrectomy and followed up for 1.5, 2, and 2 months; two patients became asymptomatic while one patient continued to have pain. These three reported patients with a history of ziv-aflibercept therapy and no reported use of other medications known to cause MRONJ developed exposed necrotic bone of the jaw. We believe that ziv-aflibercept is another medication that can potentially cause MRONJ probably through its anti-VEGF activity, similar to bevacizumab and sunitinib. PMID:28078129

  3. State-space models of head-related transfer functions for virtual auditory scene synthesis.

    PubMed

    Adams, Norman H; Wakefield, Gregory H

    2009-06-01

    This study investigates the use of reduced-order state-space models of collections of head-related transfer functions (HRTFs). Recent head-phone applications have motivated interest in binaural displays that can render multiple simultaneous virtual sound sources, acoustic reflections, and source and listener motion. In the present study, a multi-direction framework is considered that can render such phenomena by filtering source signals with a collection of HRTFs rather than individual HRTFs. The collection of HRTFs is implemented in the state-space, and approximation techniques are applied to construct low-order approximants that are indiscriminable from full-order HRTFs. Two experiments are described in which five observers are asked to discriminate between state-space and full-order renderings. Depending on the stimulus conditions and discrimination task, order thresholds of 7

  4. Temporal MRI characterization, neurobiochemical and neurobehavioral changes in a mouse repetitive concussive head injury model

    PubMed Central

    Yang, Zhihui; Wang, Ping; Morgan, Drake; Lin, Dan; Pan, Jianchun; Lin, Fan; Strang, Kevin H.; Selig, Tyler M.; Perez, Pablo D.; Febo, Marcelo; Chang, Binggong; Rubenstein, Richard; Wang, Kevin K.W.

    2015-01-01

    Single and repeated sports-related mild traumatic brain injury (mTBI), also referred to as concussion, can result in chronic post-concussive syndrome (PCS), neuropsychological and cognitive deficits, or chronic traumatic encephalopathy (CTE). However PCS is often difficult to diagnose using routine clinical, neuroimaging or laboratory evaluations, while CTE currently only can be definitively diagnosed postmortem. We sought to develop an animal model to simulate human repetitive concussive head injury for systematic study. In this study, mice received single or multiple head impacts by a stereotaxic impact device with a custom-made rubber tip-fitted impactor. Dynamic changes in MRI, neurobiochemical markers (Tau hyperphosphorylation and glia activation in brain tissues) and neurobehavioral functions such as anxiety, depression, motor function and cognitive function at various acute/subacute (1-7 day post-injury) and chronic (14-60 days post-injury) time points were examined. To explore the potential biomarkers of rCHI, serum levels of total Tau (T-Tau) and phosphorylated Tau (P-Tau) were also monitored at various time points. Our results show temporal dynamics of MRI consistent with structural perturbation in the acute phase and neurobiochemical changes (P-Tau and GFAP induction) in the subacute and chronic phase as well as development of chronic neurobehavioral changes, which resemble those observed in mTBI patients. PMID:26058556

  5. Modeling Film-Coolant Flow Characteristics at the Exit of Shower-Head Holes

    NASA Technical Reports Server (NTRS)

    Garg, Vijay K.; Gaugler, R. E. (Technical Monitor)

    2000-01-01

    The coolant flow characteristics at the hole exits of a film-cooled blade are derived from an earlier analysis where the hole pipes and coolant plenum were also discretized. The blade chosen is the VKI rotor with three staggered rows of shower-head holes. The present analysis applies these flow characteristics at the shower-head hole exits. A multi-block three-dimensional Navier-Stokes code with Wilcox's k-omega model is used to compute the heat transfer coefficient on the film-cooled turbine blade. A reasonably good comparison with the experimental data as well as with the more complete earlier analysis where the hole pipes and coolant plenum were also gridded is obtained. If the 1/7th power law is assumed for the coolant flow characteristics at the hole exits, considerable differences in the heat transfer coefficient on the blade surface, specially in the leading-edge region, are observed even though the span-averaged values of h (heat transfer coefficient based on T(sub o)-T(sub w)) match well with the experimental data. This calls for span-resolved experimental data near film-cooling holes on a blade for better validation of the code.

  6. A histomorphometric study of necrotic femoral head in rabbits treated with extracorporeal shock waves

    PubMed Central

    Ma, Huan-Zhi; Zhou, Dong-Sheng; Li, Dong; Zhang, Wei; Zeng, Bing-Fang

    2017-01-01

    [Purpose] This study aimed to determine the effectiveness and mechanisms of extracorporeal shock wave therapy in the treatment of femoral head osteonecrosis. [Subjects and Methods] Histomorphometric analysis of necrotic femoral head in rabbits treated with shock waves was performed. Bilateral osteonecrosis of femoral heads was induced with methylprednisolone and lipopolysaccharide in eight rabbits. The left limb (study side) received shock waves to the femoral head. The right limb (control side) received no shock waves. Biopsies of the femoral heads were performed at 12 weeks after shock wave therapy. [Results] Necrotic femoral heads treated with shock waves, compared with controls, had higher bone volume per tissue volume, trabecular thickness, trabecular number, osteoblast surface/bone surface, osteoid surface/bone surface, osteoid thickness, mineralizing surface/bone surface, mineralizing apposition rate, and bone formation rate. However, trabecular separation was lower in shock wave-treated femoral heads than in controls. Eroded surface/bone surface and osteoclast surface/bone surface did not differ significantly between groups. [Conclusion] The bone mass of necrotic femoral heads treated with shock waves increases. Extracorporeal shock wave may promote bone repair in necrotic femoral heads through the proliferation and activation of osteoblasts. PMID:28210032

  7. Effect of Anatomically Realistic Full-Head Model on Activation of Cortical Neurons in Subdural Cortical Stimulation—A Computational Study

    PubMed Central

    Seo, Hyeon; Kim, Donghyeon; Jun, Sung Chan

    2016-01-01

    Electrical brain stimulation (EBS) is an emerging therapy for the treatment of neurological disorders, and computational modeling studies of EBS have been used to determine the optimal parameters for highly cost-effective electrotherapy. Recent notable growth in computing capability has enabled researchers to consider an anatomically realistic head model that represents the full head and complex geometry of the brain rather than the previous simplified partial head model (extruded slab) that represents only the precentral gyrus. In this work, subdural cortical stimulation (SuCS) was found to offer a better understanding of the differential activation of cortical neurons in the anatomically realistic full-head model than in the simplified partial-head models. We observed that layer 3 pyramidal neurons had comparable stimulation thresholds in both head models, while layer 5 pyramidal neurons showed a notable discrepancy between the models; in particular, layer 5 pyramidal neurons demonstrated asymmetry in the thresholds and action potential initiation sites in the anatomically realistic full-head model. Overall, the anatomically realistic full-head model may offer a better understanding of layer 5 pyramidal neuronal responses. Accordingly, the effects of using the realistic full-head model in SuCS are compelling in computational modeling studies, even though this modeling requires substantially more effort. PMID:27273817

  8. Effect of Anatomically Realistic Full-Head Model on Activation of Cortical Neurons in Subdural Cortical Stimulation—A Computational Study

    NASA Astrophysics Data System (ADS)

    Seo, Hyeon; Kim, Donghyeon; Jun, Sung Chan

    2016-06-01

    Electrical brain stimulation (EBS) is an emerging therapy for the treatment of neurological disorders, and computational modeling studies of EBS have been used to determine the optimal parameters for highly cost-effective electrotherapy. Recent notable growth in computing capability has enabled researchers to consider an anatomically realistic head model that represents the full head and complex geometry of the brain rather than the previous simplified partial head model (extruded slab) that represents only the precentral gyrus. In this work, subdural cortical stimulation (SuCS) was found to offer a better understanding of the differential activation of cortical neurons in the anatomically realistic full-head model than in the simplified partial-head models. We observed that layer 3 pyramidal neurons had comparable stimulation thresholds in both head models, while layer 5 pyramidal neurons showed a notable discrepancy between the models; in particular, layer 5 pyramidal neurons demonstrated asymmetry in the thresholds and action potential initiation sites in the anatomically realistic full-head model. Overall, the anatomically realistic full-head model may offer a better understanding of layer 5 pyramidal neuronal responses. Accordingly, the effects of using the realistic full-head model in SuCS are compelling in computational modeling studies, even though this modeling requires substantially more effort.

  9. Establishment of a prediction model for the miRNA-based heading date characteristics of rice in the booting stage.

    PubMed

    Chen, Y C; Lin, W S; Chen, R K; Chao, Y Y; Chin, S W; Chen, F C; Lee, C Y

    2015-04-30

    Rice (Oryza sativa L.) is one of the most important food crops in the world. In Taiwan, due to the warm climate, there are two harvests annually. However, the yield and quality of rice can vary between each crop season in any given year. Previous reports have shown that microRNAs (miRNAs) play a crucial role in many developmental and physiological processes in plants. In this study, the heading date characteristics of 167 rice cultivars from the second crop season were recorded, and 27 rice cultivars were selected for preliminary microarray analysis. A total of 14 miRNAs from different heading date characteristics in 21 cultivars were selected based on significant differences in their expression profiles. Using a correlation analysis between the heading date and selected miRNA expression obtained from real-time polymerase chain reaction (PCR) assays, we developed a heading date prediction model. The model includes nine miRNA genes with corresponding R2 values of 0.8. To confirm the model, a real-time PCR analysis was performed on an additional 27 rice cultivars and we found the model predicted the heading date with accuracy. Therefore, the developed prediction may be useful in further studies aimed at confirming the reliability of the use of miRNA in molecular breeding and to increase the selection efficiency of rice cultivars and breeding.

  10. Multifocal osteonecrosis in systemic lupus erythematosus: case report and review of the literature

    PubMed Central

    Fajardo-Hermosillo, Luis D; López-López, Linnette; Nadal, Anaida; Vilá, Luis M

    2013-01-01

    Osteonecrosis is a relatively common comorbidity in systemic lupus erythematosus (SLE), but avascular necrosis in multiple sites is unusual. Multifocal osteonecrosis is defined as osteonecrotic lesions affecting three or more separate anatomic sites. We report a case of a 24-year-old woman diagnosed with SLE when she presented with mucocutaneous, haematological and mild renal manifestations. Initially, she was treated with prednisone and hydroxychloroquine and her condition remained stable. Two years later, she developed severe bilateral pretibial ulcers intractable to immunosuppressive therapy and broad-spectrum antibiotics. MRI of both legs disclosed osteonecrosis of the distal tibia, proximal tibia, distal fibula and talus bilaterally. She had elevated anticardiolipin antibodies for which she was treated with chronic anticoagulation resulting in complete healing of the leg ulcers and no further episodes of osteonecrosis. In addition to this case, we review the demographic, clinical and pharmacological features of 14 cases reported in the literature. PMID:23595183

  11. Osteonecrosis of Interphalangeal Joint of Thumb Two Months after Rattlesnake Bite.

    PubMed

    Bonasso, Patrick; Lucke-Wold, Brandon; Jacob, Glen

    2015-01-01

    This case report details the osteonecrosis of the interphalangeal (IP) joint of the thumb two months after a rattlesnake bite. It describes the clinical presentation, imaging studies, histological review, pathology review, and review of literature. Our patient was a fifty-one year-old male who obtained a poisonous snakebite to the thumb. While in the hospital for acute treatment, a blood blister was debrided. He was seen two weeks after discharge for further debridement of epidermolysis. Patient presented one month later with a hand x-ray demonstrating bony erosions, and a bone scan showing active changes in the IP joint of his right thumb. He was taken to the OR for further debridement and definitive diagnosis. Pathology results confirmed osteonecrosis with negative bone cultures. The clinical presentation, diagnosis, and operative management of osteonecrosis offer a unique challenge, especially in a patient presenting with osteonecrosis from a poisonous snakebite.

  12. Knowledge of bisphosphonate-related osteonecrosis of the Jaws among Mexican dentists

    PubMed Central

    Ibáñez-Mancera, Norma-Guadalupe; Aguilar-Rojas, Ana-Martha; Álvarez-Jardón, Ana-Pilar

    2017-01-01

    Background Bisphosphonate-related osteonecrosis is an infrequent but potentially serious complication. Its treatment remains complex, and in some cases can be mutilating. Prevention, a correct diagnosis and opportune management are crucial. Material and Methods A cross-sectional study was made, interviewing 410 dentists with the aim of assessing their knowledge of the subject. Results Practically all of the dental professionals (99.7%) were found to lack sufficient knowledge of the prevention, diagnosis and management of bisphosphonate-related osteonecrosis. Conclusions Actions including increased diffusion in the professional media and inclusion of the subject in training programs are needed in order to enhance the knowledge of bisphosphonate-related osteonecrosis among dentists and thus prevent complications in this group of patients. Key words:Knowledge, mexico, osteonecrosis, bisphosphonates. PMID:27918741

  13. Review and standardization of cell phone exposure calculations using the SAM phantom and anatomically correct head models

    PubMed Central

    Beard, Brian B; Kainz, Wolfgang

    2004-01-01

    We reviewed articles using computational RF dosimetry to compare the Specific Anthropomorphic Mannequin (SAM) to anatomically correct models of the human head. Published conclusions based on such comparisons have varied widely. We looked for reasons that might cause apparently similar comparisons to produce dissimilar results. We also looked at the information needed to adequately compare the results of computational RF dosimetry studies. We concluded studies were not comparable because of differences in definitions, models, and methodology. Therefore we propose a protocol, developed by an IEEE standards group, as an initial step in alleviating this problem. The protocol calls for a benchmark validation study comparing the SAM phantom to two anatomically correct models of the human head. It also establishes common definitions and reporting requirements that will increase the comparability of all computational RF dosimetry studies of the human head. PMID:15482601

  14. A head-to-head comparison of SCRalyze and Ledalab, two model-based methods for skin conductance analysis.

    PubMed

    Bach, Dominik R

    2014-12-01

    Model-based analysis of skin conductance responses (SCR) can furnish less noisy estimates of sympathetic arousal (SA) than operational peak scoring approaches, as shown in previous work. Here, I compare two model-based methods for analysis of evoked (stimulus-locked) SCR, implemented in two software packages, SCRalyze and Ledalab, with respect to their sensitivity in recovering SA. Four datasets are analysed to compare predictive validity, i.e. the sensitivity to distinguish pairs of SA states that are known to be different. SCRalyze was significantly better able than Ledalab to recover this known difference in four out of five tested contrasts and comparable in the remaining one. SCRalyze performed significantly better than conventional analysis in all contrasts. I conclude that the model-based method engendered in SCRalyze is currently the best available approach to provide robust and sensitive estimates of sympathetic arousal.

  15. A head-to-head comparison of SCRalyze and Ledalab, two model-based methods for skin conductance analysis

    PubMed Central

    Bach, Dominik R.

    2014-01-01

    Model-based analysis of skin conductance responses (SCR) can furnish less noisy estimates of sympathetic arousal (SA) than operational peak scoring approaches, as shown in previous work. Here, I compare two model-based methods for analysis of evoked (stimulus-locked) SCR, implemented in two software packages, SCRalyze and Ledalab, with respect to their sensitivity in recovering SA. Four datasets are analysed to compare predictive validity, i.e. the sensitivity to distinguish pairs of SA states that are known to be different. SCRalyze was significantly better able than Ledalab to recover this known difference in four out of five tested contrasts and comparable in the remaining one. SCRalyze performed significantly better than conventional analysis in all contrasts. I conclude that the model-based method engendered in SCRalyze is currently the best available approach to provide robust and sensitive estimates of sympathetic arousal. PMID:25148785

  16. Power deposition in the head and neck of an anatomically based human body model for plane wave exposures.

    PubMed

    Tinniswood, A D; Furse, C M; Gandhi, O P

    1998-08-01

    At certain frequencies, when the human head becomes a resonant structure, the power absorbed by the head and neck, when the body is exposed to a vertically polarized plane wave propagating from front to back, becomes significantly larger than would ordinarily be expected from its shadow cross section. This has possible implications in the study of the biological effects of electromagnetic fields. Additionally the frequencies at which these resonances occur are not readily predicted by simple approximations of the head in isolation. In order to determine these resonant conditions an anatomically based model of the whole human body has been used, with the finite-difference time-domain (FDTD) algorithm to accurately determine field propagation, specific absorption rate (SAR) distributions and power absorption in both the whole body and the head region (head and neck). This paper shows that resonant frequencies can be determined using two methods. The first is by use of the accurate anatomically based model (with heterogeneous tissue properties) and secondly using a model built from parallelepiped sections (for the torso and legs), an ellipsoid for the head and a cylinder for the neck. This approximation to the human body is built from homogeneous tissue the equivalent of two-thirds the conductivity and dielectric constant of that of muscle. An IBM SP-2 supercomputer together with a parallel FDTD code has been used to accommodate the large problem size. We find resonant frequencies for the head and neck at 207 MHz and 193 MHz for the isolated and grounded conditions, with absorption cross sections that are respectively 3.27 and 2.62 times the shadow cross section.

  17. An eye model for uncalibrated eye gaze estimation under variable head pose

    NASA Astrophysics Data System (ADS)

    Hnatow, Justin; Savakis, Andreas

    2007-04-01

    Gaze estimation is an important component of computer vision systems that monitor human activity for surveillance, human-computer interaction, and various other applications including iris recognition. Gaze estimation methods are particularly valuable when they are non-intrusive, do not require calibration, and generalize well across users. This paper presents a novel eye model that is employed for efficiently performing uncalibrated eye gaze estimation. The proposed eye model was constructed from a geometric simplification of the eye and anthropometric data about eye feature sizes in order to circumvent the requirement of calibration procedures for each individual user. The positions of the two eye corners and the midpupil, the distance between the two eye corners, and the radius of the eye sphere are required for gaze angle calculation. The locations of the eye corners and midpupil are estimated via processing following eye detection, and the remaining parameters are obtained from anthropometric data. This eye model is easily extended to estimating eye gaze under variable head pose. The eye model was tested on still images of subjects at frontal pose (0 °) and side pose (34 °). An upper bound of the model's performance was obtained by manually selecting the eye feature locations. The resulting average absolute error was 2.98 ° for frontal pose and 2.87 ° for side pose. The error was consistent across subjects, which indicates that good generalization was obtained. This level of performance compares well with other gaze estimation systems that utilize a calibration procedure to measure eye features.

  18. Predictions of heading date in bread wheat (Triticum aestivum L.) using QTL-based parameters of an ecophysiological model.

    PubMed

    Bogard, Matthieu; Ravel, Catherine; Paux, Etienne; Bordes, Jacques; Balfourier, François; Chapman, Scott C; Le Gouis, Jacques; Allard, Vincent

    2014-11-01

    Prediction of wheat phenology facilitates the selection of cultivars with specific adaptations to a particular environment. However, while QTL analysis for heading date can identify major genes controlling phenology, the results are limited to the environments and genotypes tested. Moreover, while ecophysiological models allow accurate predictions in new environments, they may require substantial phenotypic data to parameterize each genotype. Also, the model parameters are rarely related to all underlying genes, and all the possible allelic combinations that could be obtained by breeding cannot be tested with models. In this study, a QTL-based model is proposed to predict heading date in bread wheat (Triticum aestivum L.). Two parameters of an ecophysiological model (V sat and P base , representing genotype vernalization requirements and photoperiod sensitivity, respectively) were optimized for 210 genotypes grown in 10 contrasting location × sowing date combinations. Multiple linear regression models predicting V sat and P base with 11 and 12 associated genetic markers accounted for 71 and 68% of the variance of these parameters, respectively. QTL-based V sat and P base estimates were able to predict heading date of an independent validation data set (88 genotypes in six location × sowing date combinations) with a root mean square error of prediction of 5 to 8.6 days, explaining 48 to 63% of the variation for heading date. The QTL-based model proposed in this study may be used for agronomic purposes and to assist breeders in suggesting locally adapted ideotypes for wheat phenology.

  19. Head Lice

    MedlinePlus

    Head lice are parasitic wingless insects. They live on people's heads and feed on their blood. An adult louse ... Children ages 3-11 and their families get head lice most often. Personal hygiene has nothing to ...

  20. Head Lice

    MedlinePlus

    ... Schedules Nutrient Shortfall Questionnaire Home Diseases and Conditions Head Lice Head Lice Condition Family HealthKids and Teens Share Head Lice Table of Contents1. Overview2. Symptoms3. Causes4. Prevention5. ...

  1. Management and treatment of osteonecrosis in children and adolescents with acute lymphoblastic leukemia

    PubMed Central

    te Winkel, Mariël L.; Pieters, Rob; Wind, Ernst-Jan D.; Bessems, J.H.J.M. (Gert); van den Heuvel-Eibrink, Marry M.

    2014-01-01

    There is no consensus regarding how to manage osteonecrosis in pediatric acute lymphoblastic leukemia patients. Therefore, we performed a quality assessment of the literature with the result of a search strategy using the MESH terms osteonecrosis, children, childhood cancer, surgery, bisphosphonates, 6 hydroxymethyl-glutaryl CoA reductase inhibitors, anticoagulants and hyperbaric oxygen, and terms related to these MESH terms. A randomized controlled trial showed that osteonecrosis can be prevented by intermittent, instead of continuous, corticosteroid administration. The studies on interventions after onset of osteonecrosis were of low-quality evidence. Seven pediatric acute lymphoblastic leukemia studies described non-surgical interventions; bisphosphonates (n=5), hyperbaric oxygen therapy (n=1), or prostacyclin analogs (n=1). Safety and efficacy studies are lacking. Five studies focused on surgical interventions; none was of sufficient quality to draw definite conclusions. In conclusion, preventing osteonecrosis is feasible in a proportion of the pediatric acute lymphoblastic leukemia patients by discontinuous, instead of continuous, steroid scheduling. The questions as to how to treat childhood acute lymphoblastic leukemia patients with osteonecrosis cannot be answered as good-quality studies are lacking. PMID:24598854

  2. Management and treatment of osteonecrosis in children and adolescents with acute lymphoblastic leukemia.

    PubMed

    Te Winkel, Mariël L; Pieters, Rob; Wind, Ernst-Jan D; Bessems, J H J M Gert; van den Heuvel-Eibrink, Marry M

    2014-03-01

    There is no consensus regarding how to manage osteonecrosis in pediatric acute lymphoblastic leukemia patients. Therefore, we performed a quality assessment of the literature with the result of a search strategy using the MESH terms osteonecrosis, children, childhood cancer, surgery, bisphosphonates, 6 hydroxymethyl-glutaryl CoA reductase inhibitors, anticoagulants and hyperbaric oxygen, and terms related to these MESH terms. A randomized controlled trial showed that osteonecrosis can be prevented by intermittent, instead of continuous, corticosteroid administration. The studies on interventions after onset of osteonecrosis were of low-quality evidence. Seven pediatric acute lymphoblastic leukemia studies described non-surgical interventions; bisphosphonates (n=5), hyperbaric oxygen therapy (n=1), or prostacyclin analogs (n=1). Safety and efficacy studies are lacking. Five studies focused on surgical interventions; none was of sufficient quality to draw definite conclusions. In conclusion, preventing osteonecrosis is feasible in a proportion of the pediatric acute lymphoblastic leukemia patients by discontinuous, instead of continuous, steroid scheduling. The questions as to how to treat childhood acute lymphoblastic leukemia patients with osteonecrosis cannot be answered as good-quality studies are lacking.

  3. The New York Head-A precise standardized volume conductor model for EEG source localization and tES targeting.

    PubMed

    Huang, Yu; Parra, Lucas C; Haufe, Stefan

    2016-10-15

    In source localization of electroencephalograpic (EEG) signals, as well as in targeted transcranial electric current stimulation (tES), a volume conductor model is required to describe the flow of electric currents in the head. Boundary element models (BEM) can be readily computed to represent major tissue compartments, but cannot encode detailed anatomical information within compartments. Finite element models (FEM) can capture more tissue types and intricate anatomical structures, but with the higher precision also comes the need for semi-automated segmentation, and a higher computational cost. In either case, adjusting to the individual human anatomy requires costly magnetic resonance imaging (MRI), and thus head modeling is often based on the anatomy of an 'arbitrary' individual (e.g. Colin27). Additionally, existing reference models for the human head often do not include the cerebro-spinal fluid (CSF), and their field of view excludes portions of the head and neck-two factors that demonstrably affect current-flow patterns. Here we present a highly detailed FEM, which we call ICBM-NY, or "New York Head". It is based on the ICBM152 anatomical template (a non-linear average of the MRI of 152 adult human brains) defined in MNI coordinates, for which we extended the field of view to the neck and performed a detailed segmentation of six tissue types (scalp, skull, CSF, gray matter, white matter, air cavities) at 0.5mm(3) resolution. The model was solved for 231 electrode locations. To evaluate its performance, additional FEMs and BEMs were constructed for four individual subjects. Each of the four individual FEMs (regarded as the 'ground truth') is compared to its BEM counterpart, the ICBM-NY, a BEM of the ICBM anatomy, an 'individualized' BEM of the ICBM anatomy warped to the individual head surface, and FEMs of the other individuals. Performance is measured in terms of EEG source localization and tES targeting errors. Results show that the ICBM-NY outperforms

  4. Volume-averaged SAR in adult and child head models when using mobile phones: a computational study with detailed CAD-based models of commercial mobile phones.

    PubMed

    Keshvari, Jafar; Heikkilä, Teemu

    2011-12-01

    Previous studies comparing SAR difference in the head of children and adults used highly simplified generic models or half-wave dipole antennas. The objective of this study was to investigate the SAR difference in the head of children and adults using realistic EMF sources based on CAD models of commercial mobile phones. Four MRI-based head phantoms were used in the study. CAD models of Nokia 8310 and 6630 mobile phones were used as exposure sources. Commercially available FDTD software was used for the SAR calculations. SAR values were simulated at frequencies 900 MHz and 1747 MHz for Nokia 8310, and 900 MHz, 1747 MHz and 1950 MHz for Nokia 6630. The main finding of this study was that the SAR distribution/variation in the head models highly depends on the structure of the antenna and phone model, which suggests that the type of the exposure source is the main parameter in EMF exposure studies to be focused on. Although the previous findings regarding significant role of the anatomy of the head, phone position, frequency, local tissue inhomogeneity and tissue composition specifically in the exposed area on SAR difference were confirmed, the SAR values and SAR distributions caused by generic source models cannot be extrapolated to the real device exposures. The general conclusion is that from a volume averaged SAR point of view, no systematic differences between child and adult heads were found.

  5. Osteonecrosis in children after allogeneic hematopoietic cell transplantation: study of prevalence, risk factors and longitudinal changes using MR imaging.

    PubMed

    Sharma, S; Leung, W-H; Deqing, P; Yang, J; Rochester, R; Britton, L; Neel, M D; Ness, K K; Kaste, S C

    2012-08-01

    Osteonecrosis after hematopoietic SCT (HCT) has seldom been addressed in pediatric populations. At our institution, since January 2002, children undergoing allogeneic HCT (alloHCT) receive yearly follow-up magnetic resonance imaging (MR) of hips and knees. To estimate the prevalence, longitudinal changes and associated risk factors for osteonecrosis after alloHCT, we reviewed MRs for children who underwent single alloHCT during the study period. We analyzed 149 of 344 patients who had post-HCT MR imaging performed (84 males; median age 11 years (range, 0.5-21 years)), median follow-up time was 32.6 months (range, 2.8-97.2 months). In all, 44 (29.5%) developed osteonecrosis of hips and/or knees; of those, 20 (45%) had at least 30% epiphyseal involvement. In 23 (52%), osteonecrosis lesions were identified in the first and in 43 (98%) by the third yearly scan. Knees were more frequently involved than hips; severity of osteonecrosis was greater in hips. Those who had pre-alloHCT osteonecrosis, two patients' hips and six patients' knees resolved completely; three patients' osteonecrosis lesions regressed after alloHCT. On risk factor analysis, age at time of alloHCT (P=0.051) and osteonecrosis identified by MRs before alloHCT (P=0.001) were the primary risk factors. This analysis shows that preventive strategies for osteonecrosis in this population should focus on measures to minimize risk factors before alloHCT.

  6. Thermal modeling of head disk interface system in heat assisted magnetic recording

    SciTech Connect

    Vemuri, Sesha Hari; Seung Chung, Pil; Jhon, Myung S.; Min Kim, Hyung

    2014-05-07

    A thorough understanding of the temperature profiles introduced by the heat assisted magnetic recording is required to maintain the hotspot at the desired location on the disk with minimal heat damage to other components. Here, we implement a transient mesoscale modeling methodology termed lattice Boltzmann method (LBM) for phonons (which are primary carriers of energy) in the thermal modeling of the head disk interface (HDI) components, namely, carbon overcoat (COC). The LBM can provide more accurate results compared to conventional Fourier methodology by capturing the nanoscale phenomena due to ballistic heat transfer. We examine the in-plane and out-of-plane heat transfer in the COC via analyzing the temperature profiles with a continuously focused and pulsed laser beam on a moving disk. Larger in-plane hotspot widening is observed in continuously focused laser beam compared to a pulsed laser. A pulsed laser surface develops steeper temperature gradients compared to continuous hotspot. Furthermore, out-of-plane heat transfer from the COC to the media is enhanced with a continuous laser beam then a pulsed laser, while the temperature takes around 140 fs to reach the bottom surface of the COC. Our study can lead to a realistic thermal model describing novel HDI material design criteria for the next generation of hard disk drives with ultra high recording densities.

  7. Macroscopic Model for Head-On Binary Droplet Collisions in a Gaseous Medium

    NASA Astrophysics Data System (ADS)

    Li, Jie

    2016-11-01

    In this Letter, coalescence-bouncing transitions of head-on binary droplet collisions are predicted by a novel macroscopic model based entirely on fundamental laws of physics. By making use of the lubrication theory of Zhang and Law [Phys. Fluids 23, 042102 (2011)], we have modified the Navier-Stokes equations to accurately account for the rarefied nature of the interdroplet gas film. Through the disjoint pressure model, we have incorporated the intermolecular van der Waals forces. Our model does not use any adjustable (empirical) parameters. It therefore encompasses an extreme range of length scales (more than 5 orders of magnitude): from those of the external flow in excess of the droplet size (a few hundred μ m ) to the effective range of the van der Waals force around 10 nm. A state of the art moving adaptive mesh method, capable of resolving all the relevant length scales, has been employed. Our numerical simulations are able to capture the coalescence-bouncing and bouncing-coalescence transitions that are observed as the collision intensity increases. The predicted transition Weber numbers for tetradecane and water droplet collisions at different pressures show good agreement with published experimental values. Our study also sheds new light on the roles of gas density, droplet size, and mean free path in the rupture of the gas film.

  8. Brain Response to Primary Blast Wave Using Validated Finite Element Models of Human Head and Advanced Combat Helmet

    PubMed Central

    Zhang, Liying; Makwana, Rahul; Sharma, Sumit

    2013-01-01

    Blast-induced traumatic brain injury has emerged as a “signature injury” in combat casualty care. Present combat helmets are designed primarily to protect against ballistic and blunt impacts, but the current issue with helmets is protection concerning blasts. In order to delineate the blast wave attenuating capability of the Advanced Combat Helmet (ACH), a finite element (FE) study was undertaken to evaluate the head response against blast loadings with and without helmet using a partially validated FE model of the human head and ACH. Four levels of overpressures (0.27–0.66 MPa) from the Bowen’s lung iso-damage threshold curves were used to simulate blast insults. Effectiveness of the helmet with respect to head orientation was also investigated. The resulting biomechanical responses of the brain to blast threats were compared for human head with and without the helmet. For all Bowen’s cases, the peak intracranial pressures (ICP) in the head ranged from 0.68 to 1.8 MPa in the coup cortical region. ACH was found to mitigate ICP in the head by 10–35%. Helmeted head resulted in 30% lower average peak brain strains and product of strain and strain rate. Among three blast loading directions with ACH, highest reduction in peak ICP (44%) was due to backward blasts whereas the lowest reduction in peak ICP and brain strains was due to forward blast (27%). The biomechanical responses of a human head to primary blast insult exhibited directional sensitivity owing to the different geometry contours and coverage of the helmet construction and asymmetric anatomy of the head. Thus, direction-specific tolerances are needed in helmet design in order to offer omni-directional protection for the human head. The blasts of varying peak overpressures and durations that are believed to produce the same level of lung injury produce different levels of mechanical responses in the brain, and hence “iso-damage” curves for brain injury are likely different than the Bowen

  9. [The mathematical modelling of the processes in the natural multiplication of human lice (exemplified by the head louse population].

    PubMed

    Boev, B V; Barabash, V K; Tarasevich, I V

    1991-01-01

    Methods of mathematical modelling and prediction of louse propagation processes in the natural habitation medium are presented. Theoretical and experimental data on head louse ecology served the basis for the elaboration of a mathematical model predicting the population dynamics. The model structure corresponds to 3 stages of louse development cycle (eggs, larva, lice) and parameters corresponding to natural characteristics of louse propagation process: mean lifespan of each individual during each phase of the cycle, age, fertility and so forth. The model helped to study some properties of the population, assess maximum rate of head louse population growth, detect threshold effects, establish the effects of coefficients, limiting the number of louse per unit of the body surface. The model made it possible to formulate necessary data (distribution functions) for the creation of the mathematical model of Pediculosis.

  10. Investigation of tDCS volume conduction effects in a highly realistic head model

    NASA Astrophysics Data System (ADS)

    Wagner, S.; Rampersad, S. M.; Aydin, Ü.; Vorwerk, J.; Oostendorp, T. F.; Neuling, T.; Herrmann, C. S.; Stegeman, D. F.; Wolters, C. H.

    2014-02-01

    Objective. We investigate volume conduction effects in transcranial direct current stimulation (tDCS) and present a guideline for efficient and yet accurate volume conductor modeling in tDCS using our newly-developed finite element (FE) approach. Approach. We developed a new, accurate and fast isoparametric FE approach for high-resolution geometry-adapted hexahedral meshes and tissue anisotropy. To attain a deeper insight into tDCS, we performed computer simulations, starting with a homogenized three-compartment head model and extending this step by step to a six-compartment anisotropic model. Main results. We are able to demonstrate important tDCS effects. First, we find channeling effects of the skin, the skull spongiosa and the cerebrospinal fluid compartments. Second, current vectors tend to be oriented towards the closest higher conducting region. Third, anisotropic WM conductivity causes current flow in directions more parallel to the WM fiber tracts. Fourth, the highest cortical current magnitudes are not only found close to the stimulation sites. Fifth, the median brain current density decreases with increasing distance from the electrodes. Significance. Our results allow us to formulate a guideline for volume conductor modeling in tDCS. We recommend to accurately model the major tissues between the stimulating electrodes and the target areas, while for efficient yet accurate modeling, an exact representation of other tissues is less important. Because for the low-frequency regime in electrophysiology the quasi-static approach is justified, our results should also be valid for at least low-frequency (e.g., below 100 Hz) transcranial alternating current stimulation.

  11. Osteonecrosis of the jaw in cancer patients receiving IV bisphosphonates.

    PubMed

    Van Poznak, Catherine; Estilo, Cherry

    2006-08-01

    Cases of osteonecrosis of the jaw (ONJ) have been reported with an increasing frequency over the past few years. ONJ is most often identified in patients with cancer who are receiving intravenous bisphosphonate therapy but it has also been diagnosed in patients receiving oral bisphosphonates for nonmalignant conditions. The condition involves exposed bone of the maxilla or mandible. Although it is often associated with a recent dental surgical procedure, spontaneous ONJ can also occur. Patients commonly present with symptoms. Through case reporting and clinical experience, there is a suggestion that the incidence of ONJ in patients with cancer receiving intravenous bisphosphonates ranges between 1% and 10%. Management of ONJ focuses on maximizing oral health, conservative actions with mouth rinses, antibiotics, and avoidance of unnecessary invasive dental procedures. The currently available data on ONJ are reviewed here.

  12. Osteoporosis and Bisphosphonate-Related Osteonecrosis of the Jaw Bone

    PubMed Central

    Villa, Alessandro; Castiglioni, Stefano; Peretti, Alessandro; Omodei, Marco; Ferrieri, Giovanni B.; Abati, Silvio

    2011-01-01

    The aim of this longitudinal study is to present data from 76 female patients treated with bisphosphonates (BPs) for postmenopausal osteoporosis and referred to the Unit of Oral Diagnosis and Day Surgery of the University of Milano for diagnosis and treatment. All patients received a thorough oral examination. The diagnosis of osteonecrosis of the jaw bone (ONJ) was made from radiographic and clinical findings. 9% of individuals had BRONJ at first visit. Patients with dental or periodontal abscess were significantly more likely to develop BRONJ (OR: 2.9, 95% CI 0.5–15.9). Patients with osteoporosis receiving BPs may develop BRONJ, especially in the presence of an active infectious process in the mouth. Clinicians should carefully follow up on individuals receiving bisphosphonates therapy to avoid the occurrence of osteonecrotic lesions. PMID:22389800

  13. An Ex Vivo Model in Human Femoral Heads for Histopathological Study and Resonance Frequency Analysis of Dental Implant Primary Stability

    PubMed Central

    Hernández-Cortés, Pedro; Galindo-Moreno, Pablo; Catena, Andrés; Ortega-Oller, Inmaculada; Salas-Pérez, José; Gómez-Sánchez, Rafael; Aguilar, Mariano; Aguilar, David

    2014-01-01

    Objective. This study was designed to explore relationships of resonance frequency analysis (RFA)—assessed implant stability (ISQ values) with bone morphometric parameters and bone quality in an ex vivo model of dental implants placed in human femoral heads and to evaluate the usefulness of this model for dental implant studies. Material and Methods. This ex vivo study included femoral heads from 17 patients undergoing surgery for femoral neck fracture due to osteoporosis (OP) (n = 7) or for total prosthesis joint replacement due to severe hip osteoarthrosis (OA) (n = 10). Sixty 4.5 × 13 mm Dentsply Astra implants were placed, followed by RFA. CD44 immunohistochemical analysis for osteocytes was also carried out. Results. As expected, the analysis yielded significant effects of femoral head type (OA versus OA) (P < 0.001), but not of the implants (P = 0.455) or of the interaction of the two factors (P = 0.848). Bonferroni post hoc comparisons showed a lower mean ISQ for implants in decalcified (50.33 ± 2.92) heads than in fresh (66.93 ± 1.10) or fixated (70.77 ± 1.32) heads (both P < 0.001). The ISQ score (fresh) was significantly higher for those in OA (73.52 ± 1.92) versus OP (67.13 ± 1.09) heads. However, mixed linear analysis showed no significant association between ISQ scores and morphologic or histomorphometric results (P > 0.5 in all cases), and no significant differences in ISQ values were found as a function of the length or area of the cortical layer (both P > 0.08). Conclusion. Although RFA-determined ISQ values are not correlated with morphometric parameters, they can discriminate bone quality (OP versus OA). This ex vivo model is useful for dental implant studies. PMID:24995307

  14. The natural course of spontaneous osteonecrosis of the knee (SPONK)

    PubMed Central

    Juréus, Jan; Lindstrand, Anders; Geijer, Mats; Robertsson, Otto; Tägil, Magnus

    2013-01-01

    Background and purpose Spontaneous osteonecrosis of the knee (SPONK) is a painful lesion in the elderly, frequently leading to osteoarthritis and subsequent knee surgery. We evaluated the natural course and long-term consequences of SPONK in terms of need for major knee surgery. Methods Between 1982 and 1988, 40 consecutive patients were diagnosed with SPONK. The short-term outcome has been reported previously (1991). After 1–7 years, 10 patients had a good radiographic outcome and 30 were considered failures, developing osteoarthritis. In 2012, all 40 of the patients were matched with the Swedish Knee Arthroplasty Register (SKAR) and their medical records were reviewed to evaluate the long-term need for major knee surgery. Results At the 2012 review, 33 of the 40 patients had died. The mean follow-up time from diagnosis to surgery, death, or end of study was 9 (1–27) years. 17 of 40 patients had had major knee surgery with either arthroplasty (15) or osteotomy (2). All operated patients but 1 were in the radiographic failure group and had developed osteoarthritis in the study from 1991. 6 of 7 patients with large lesions (> 40% of the AP radiographic view of the condyle) at the time of the diagnosis were operated. None of the 10 patients with a lesion of less than 20% were ever operated. Interpretation It appears that the size of the osteonecrotic lesion can be used to predict the outcome. Patients showing early signs of osteoarthritis or with a large osteonecrosis have a high risk of later major knee surgery. PMID:23799344

  15. Folic acid enhances early functional recovery in a piglet model of pediatric head injury.

    PubMed

    Naim, Maryam Y; Friess, Stuart; Smith, Colin; Ralston, Jill; Ryall, Karen; Helfaer, Mark A; Margulies, Susan S

    2010-01-01

    For stroke and spinal cord injury, folic acid supplementation has been shown to enhance neurodevelopment and to provide neuroprotection. We hypothesized that folic acid would reduce brain injury and improve neurological outcome in a neonatal piglet model of traumatic brain injury (TBI), using 4 experimental groups of 3- to 5-day-old female piglets. Two groups were intubated, anesthetized and had moderate brain injury induced by rapid axial head rotation without impact. One group of injured (Inj) animals received folic acid (Fol; 80 μg/kg) by intraperitoneal (IP) injection 15 min following injury, and then daily for 6 days (Inj + Fol; n = 7). The second group of injured animals received an IP injection of saline (Sal) at the same time points (Inj + Sal; n = 8). Two uninjured (Uninj) control groups (Uninj + Fol, n = 8; Uninj + Sal, n = 7) were intubated, anesthetized and received folic acid (80 μg/kg) or saline by IP injection at the same time points as the injured animals following a sham procedure. Animals underwent neurobehavioral and cognitive testing on days 1 and 4 following injury to assess behavior, memory, learning and problem solving. Serum folic acid and homocysteine levels were collected prior to injury and again before euthanasia. The piglets were euthanized 6 days following injury, and their brains were perfusion fixed for histological analysis. Folic acid levels were significantly higher in both Fol groups on day 6. Homocysteine levels were not affected by treatment. On day 1 following injury, the Inj + Fol group showed significantly more exploratory interest, and better motor function, learning and problem solving compared to the Inj + Sal group. Inj + Fol animals had a significantly lower cognitive composite dysfunction score compared to all other groups on day 1. These functional improvements were not seen on day 4 following injury. Axonal injury measured by β-amyloid precursor protein staining 6 days after injury was not affected by treatment

  16. Folic Acid Enhances Early Functional Recovery in a Piglet Model of Pediatric Head Injury

    PubMed Central

    Naim, Maryam Y.; Friess, Stuart; Smith, Colin; Ralston, Jill; Ryall, Karen; Helfaer, Mark A.; Margulies, Susan S.

    2011-01-01

    For stroke and spinal cord injury, folic acid supplementation has been shown to enhance neurodevelopment and to provide neuroprotection. We hypothesized that folic acid would reduce brain injury and improve neurological outcome in a neonatal piglet model of traumatic brain injury (TBI), using 4 experimental groups of 3- to 5-day-old female piglets. Two groups were intubated, anesthetized and had moderate brain injury induced by rapid axial head rotation without impact. One group of injured (Inj) animals received folic acid (Fol; 80 μg/kg) by intraperitoneal (IP) injection 15 min following injury, and then daily for 6 days (Inj + Fol; n = 7). The second group of injured animals received an IP injection of saline (Sal) at the same time points (Inj + Sal; n = 8). Two uninjured (Uninj) control groups (Uninj + Fol, n = 8; Uninj + Sal, n = 7) were intubated, anesthetized and received folic acid (80 μg/kg) or saline by IP injection at the same time points as the injured animals following a sham procedure. Animals underwent neurobehavioral and cognitive testing on days 1 and 4 following injury to assess behavior, memory, learning and problem solving. Serum folic acid and homocysteine levels were collected prior to injury and again before euthanasia. The piglets were euthanized 6 days following injury, and their brains were perfusion fixed for histological analysis. Folic acid levels were significantly higher in both Fol groups on day 6. Homocysteine levels were not affected by treatment. On day 1 following injury, the Inj + Fol group showed significantly more exploratory interest, and better motor function, learning and problem solving compared to the Inj + Sal group. Inj + Fol animals had a significantly lower cognitive composite dysfunction score compared to all other groups on day 1. These functional improvements were not seen on day 4 following injury. Axonal injury measured by β-amyloid precursor protein staining 6 days after injury was not affected by treatment

  17. A Modeling of Cerebral Blood Flow Changes due to Head Motion for fNIRS

    NASA Astrophysics Data System (ADS)

    Takahashi, Kosuke; Tanaka, Takayuki; Nara, Hiroyuki; Kaneko, Shun'ichi; Inoue, Masao; Shimizu, Shunji; Kojima, Satoru

    2013-04-01

    A method is proposed for measuring brain activity during exercises involving head motion by using functional near-infrared spectroscopy (fNIRS), which investigates cerebral hemodynamics. Obtaining measurements during exercise is difficult because cerebral blood flow changes due to the head motion component (HMC), in addition to neural activity. HMC is an undesirable artifact in the measurement of hemodynamic response caused by neural activity, and as such, it must be estimated and eliminated. In our experiments, cerebral blood flow and head motion were measured during repeated passive forward bending of the subjects. Head motion was measured by 3-D motion capture, and HMC was estimated by deriving a relation between head motion and cerebral blood flow, where the pitch angle was found to be suitable for estimating HMC. In this research, an assumption was made that cerebral blood flow caused by neural activity and that caused by postural change were additive, and thus HMC was eliminated by subtraction.

  18. The Evaluation of a Three-Tier Model of Positive Behavior Interventions and Supports for Preschoolers in Head Start

    ERIC Educational Resources Information Center

    Stanton-Chapman, Tina L.; Walker, Virginia L.; Voorhees, Mary D.; Snell, Martha E.

    2016-01-01

    The purpose of this study was to evaluate the overall effectiveness of a three-tier model of positive behavior interventions and supports (PBIS), which was developed and tested in Head Start (HS) programs. Ten HS classrooms from five HS programs participated in the current study. Results indicated that PBIS was effective in improving classroom…

  19. Osteonecrosis following short-term, low-dose oral corticosteroids: a population-based study of 24 million patients.

    PubMed

    Dilisio, Matthew F

    2014-07-01

    Although the association between chronic, high-dose corticosteroid use and osteonecrosis is well known, the incidence of osteonecrosis following short-term, low-dose steroid taper packs has never been reported across a large population. The goal of this study was to report the incidence and risk of osteonecrosis after methylprednisolone taper pack (MTP) prescriptions in a multicenter electronic medical records database. A commercially available software platform was used to evaluate the records of 24,533,880 patients to determine the incidence of osteonecrosis in patients who had received single or multiple MTP over a 12-year period. This was compared with the incidence of osteonecrosis in patients who had never been prescribed an MTP. Patients with a history of osteonecrosis or prior corticosteroid use were excluded from the study. A total of 98,390 patients were identified who had received a single MTP. One hundred thirty (0.132%; 95% confidence interval [CI], 0.176%-0.283%) of these patients were subsequently diagnosed with osteonecrosis. The incidence of osteonecrosis in patients who had been prescribed 2 or more MTPs was 0.230% (95% CI, 0.176%-0.283%). Compared with the 0.083% incidence of osteonecrosis in the control group that had never been prescribed an MTP, the relative risk of osteonecrosis after the prescription of a single MTP or multiple MTPs was 1.591 and 2.763, respectively, with a statistically significant difference between cohorts (P<.001). Short-term, low-dose oral corticosteroid administration may be associated with a low but statistically significant increased incidence of osteonecrosis when compared with patients who have never been prescribed a steroid product.

  20. Evaluation of an algorithm ascertaining cases of osteonecrosis of the jaw in the Swedish National Patient Register

    PubMed Central

    Bergdahl, Johan; Jarnbring, Fredrik; Ehrenstein, Vera; Gammelager, Henrik; Granath, Fredrik; Kieler, Helle; Svensson, Madeleine; Tell, Grethe S; Lagerros, Ylva Trolle

    2013-01-01

    Background Osteonecrosis of the jaw (ONJ) is a medical condition associated with antiresorptive drugs, among others, used to treat osteoporosis and bone metastasis. Currently, there is no consensus regarding the definition of ONJ, and no ONJ-specific International Classification of Diseases-10 code exists. Therefore, register-based studies of this condition may be troublesome. Purpose To evaluate an algorithm ascertaining ONJ cases in an attempt to facilitate future assessments of ONJ in clinical and epidemiological studies. Methods By means of the Patient Register and the Prescribed Drug Register, we identified all postmenopausal female residents in Sweden from 2005 through 2009. To identify potential cases of ONJ, we employed an algorithm including the following conditions: periapical abscess with sinus, inflammatory conditions of jaws, alveolitis of jaws, idiopathic aseptic necrosis of bone, osteonecrosis due to drugs, osteonecrosis due to previous trauma, other secondary osteonecrosis, other osteonecrosis, and unspecified osteonecrosis. Women seen at departments of oral and maxillofacial surgery, with at least one of the conditions, were classified as potential cases of ONJ. Conditions in anatomic sites other than the jaw were excluded. Validation was performed through medical record review. Case confirmation was based on the ONJ definition by the American Association of Oral and Maxillofacial Surgeons. The algorithm was evaluated by positive predictive values (PPVs) stratified by diagnosis. Results For the 87 potential cases identified through our algorithm, the medical records were obtained for 83. The overall PPV was 18% (95% confidence interval (CI) 10%–28%). The highest PPV was observed in osteonecrosis due to drugs (83%, 95% CI 36%–100%). Several diagnoses had a PPV of 0 or were not used at all (periapical abscess with sinus, alveolitis of jaws, idiopathic aseptic necrosis of bone, osteonecrosis due to previous trauma, other secondary osteonecrosis

  1. SU-C-BRF-03: PCA Modeling of Anatomical Changes During Head and Neck Radiation Therapy

    SciTech Connect

    Chetvertkov, M; Kim, J; Siddiqui, F; Kumarasiri, A; Chetty, I; Gordon, J

    2014-06-15

    Purpose: To develop principal component analysis (PCA) models from daily cone beam CTs (CBCTs) of head and neck (H and N) patients that could be used prospectively in adaptive radiation therapy (ART). Methods: : For 7 H and N patients, Pinnacle Treatment Planning System (Philips Healthcare) was used to retrospectively deformably register daily CBCTs to the planning CT. The number N of CBCTs per treatment course ranged from 14 to 22. For each patient a PCA model was built from the deformation vector fields (DVFs), after first subtracting the mean DVF, producing N eigen-DVFs (EDVFs). It was hypothesized that EDVFs with large eigenvalues represent the major anatomical deformations during the course of treatment, and that it is feasible to relate each EDVF to a clinically meaningful systematic or random change in anatomy, such as weight loss, neck flexion, etc. Results: DVFs contained on the order of 3×87×87×58=1.3 million scalar values (3 times the number of voxels in the registered volume). The top 3 eigenvalues accounted for ∼90% of variance. Anatomical changes corresponding to an EDVF were evaluated by generating a synthetic DVF, and applying that DVF to the CT to produce a synthetic CBCT. For all patients, the EDVF for the largest eigenvalue was interpreted to model weight loss. The EDVF for other eigenvalues appeared to represented quasi-random fraction-to-fraction changes. Conclusion: The leading EDVFs from single-patient PCA models have tentatively been identified with weight loss changes during treatment. Other EDVFs are tentatively identified as quasi-random inter-fraction changes. Clean separation of systematic and random components may require further work. This work is expected to facilitate development of population-based PCA models that can be used to prospectively identify significant anatomical changes, such as weight loss, early in treatment, triggering replanning where beneficial.

  2. Automated Sperm Head Detection Using Intersecting Cortical Model Optimised by Particle Swarm Optimization

    PubMed Central

    Tan, Weng Chun; Mat Isa, Nor Ashidi

    2016-01-01

    In human sperm motility analysis, sperm segmentation plays an important role to determine the location of multiple sperms. To ensure an improved segmentation result, the Laplacian of Gaussian filter is implemented as a kernel in a pre-processing step before applying the image segmentation process to automatically segment and detect human spermatozoa. This study proposes an intersecting cortical model (ICM), which was derived from several visual cortex models, to segment the sperm head region. However, the proposed method suffered from parameter selection; thus, the ICM network is optimised using particle swarm optimization where feature mutual information is introduced as the new fitness function. The final results showed that the proposed method is more accurate and robust than four state-of-the-art segmentation methods. The proposed method resulted in rates of 98.14%, 98.82%, 86.46% and 99.81% in accuracy, sensitivity, specificity and precision, respectively, after testing with 1200 sperms. The proposed algorithm is expected to be implemented in analysing sperm motility because of the robustness and capability of this algorithm. PMID:27632581

  3. Impact of Model Uncertainty Description on Assimilating Hydraulic Head into the MIKE-SHE Distributed Hydrological Model

    NASA Astrophysics Data System (ADS)

    Zhang, D.; Madsen, H.; Ridler, M. E.; Rasmussen, J.; Refsgaard, J.; Jensen, K.

    2013-12-01

    Catchment-scale hydrological models are used as prediction tools to solve major challenges in water resources management. The reliability of hydrological model predictions is inevitably affected by the amount of information available to set up and calibrate the model. Data assimilation (DA) which combines complementary information from measurements and models has proven to be a powerful and promising tool in numerous research studies to improve model predictions. Especially, the ensemble Kalman filter (EnKF) which is a popular sequential data assimilation technique, has been extensively studied in the earth sciences for assimilating in-situ measurements and remote sensing data. However, one of the major challenges in data assimilation to optimally combine model and measurements is the description of model uncertainty. Only few studies have been reported for defining appropriate model uncertainty in hydrological DA. Modeling uncertainties can be conceptually different in different applications. Traditionally, model uncertainty is represented by parameter uncertainty with corresponding parameter statistics determined by inverse modeling. In most hydrological DA applications, however, model uncertainty is defined by experience using simple statistical descriptions of different uncertainty sources. In this work, both the uncertainty derived from inverse modeling and from empirical knowledge are used and analyzed. A combination of parameter-based, forcing-based and state-based model error is implemented in the EnKF framework for assimilating groundwater hydraulic heads into a catchment-scale model of the Karup Catchment in Denmark using the distributed and integrated hydrological model MIKE SHE. A series of synthetic identical twin experiments are carried out to analyze the impact of different model error assumptions on the feasibility and efficiency of the assimilation. The optimality of the EnKF underlying twin test provides possibilities to diagnose model error

  4. Head-Down Tilt with Balanced Traction as a Model for Simulating Spinal Acclimation to Microgravity

    NASA Technical Reports Server (NTRS)

    Ballard, R. E.; Styf, J. R.; Watenpaugh, D. E.; Fechner, K.; Haruna, Y.; Kahan, N. J.; Hargens, A. R.

    1994-01-01

    Astronauts experience total body height increases of 4 to 7 cm in microgravity. Thus, stretching of the spinal cord, nerve roots, and muscular and ligamentous tissues may be responsible for the hyperreflexia, back pain, and muscular atrophy associated with exposure to microgravity. Axial compression of the spine makes 6 deg. head-down tilt (HDT) an unsuitable model for spinal acclimation to microgravity. However, this axial compression may be counteracted by balanced traction consisting of 10% body weight (sin 6 deg. = 0.1) applied to the legs. Six healthy male subjects underwent 3 days each of 60 HDT with balanced traction and horizontal bed rest (HBR), with a 2 week recovery period between treatments. Total body and spine length, lumbar disc height, back pain, erector spinae intramuscular pressure, and ankle joint torque were measured before, during and after each treatment. Total body and spine (processes of L5 - C7) lengths increased significantly more during HDT with balanced traction (22 +/- 8 mm and 25 +/- 8 mm, respectively) than during HBR (16 +/- 4 mm and 14 +/- 9 mm, respectively). Back and leg pain were significantly greater during HDT with balanced traction than during HBR. The distance between the lower end plate of L4 and the upper endplate of S1, as measured by sonography, increased significantly in both treatments to the same degree (2.9 +/- 1.9 mm, HDT with balanced traction; 3.3 +/- 1.5 mm, HBR). Intramuscular pressure of the erector spinae muscles and maximal ankle joint torque were unaltered with both models. While neither model increased height to the magnitude observed in microgravity, HDT with balanced traction may be a better model for simulating the body lengthening and back pain experienced in microgravity.

  5. Impact of Full-Day Head Start Prekindergarten Class Model on Student Academic Performance, Cognitive Skills, and Learning Behaviors by the End of Grade 2. Evaluation Brief

    ERIC Educational Resources Information Center

    Zhao, Huafang; Modarresi, Shahpar

    2013-01-01

    This brief describes the impact of the Montgomery County (Maryland) Public Schools (MCPS) 2007-2008 full-day Head Start prekindergarten (pre-K) class model on student academic performance, cognitive skills, and learning behaviors by the end of Grade 2. This is the fourth impact study of the MCPS full-day Head Start pre-K class model. The following…

  6. A head-to-head hands-on comparison of ERCP mechanical simulator (EMS) and Ex-vivo Porcine Stomach Model (PSM).

    PubMed

    Leung, Joseph W; Wang, Dong; Hu, Bing; Lim, Brian; Leung, Felix W

    2011-07-01

    BACKGROUND: ERCP mechanical simulator (EMS) and ex-vivo porcine stomach model (PSM) have been described. No direct comparison was reported on endoscopists' perception regarding their efficacy for ERCP training OBJECTIVE: Comparative assessment of EMS and PSM. DESIGN: Questionnaire survey before and after practice. SETTING: Hands-on practice workshops. SUBJECTS: 22 endoscopists with prior experience in 111±225 (mean±SD) ERCP. INTERVENTIONS: Participants performed scope insertion, selective bile duct cannulation with guide wire and insertion of a single biliary stent. Simulated fluoroscopy with external pin-hole camera (EMS), or with additional transillumination (PSM) was used to monitor exchange of accessories. MAIN OUTCOME MEASURE: Participants rated their understanding and confidence before and after hands-on practice, and credibility of each simulator for ERCP training. Comparative efficacy of EMS and PSM for ERCP education was scored (1=not, 10=very) based on pre and post practice surveys: realism (tissue pliability, papilla anatomy, visual/cannulation realism, wire manipulation, simulated fluoroscopy, overall experience); usefulness (assessment of results, supplementing clinical experience, easy for trainees to learn new skills) and application (overall ease of use, prepare trainees to use real instrument and ease of incorporation into training). RESULTS: Before hands-on practice, both EMS and PSM received high scores. After practice, there was a significantly greater increase in confidence score for EMS than PSM (p<0.003). Participants found EMS more useful for training (p=0.017). LIMITATIONS: Subjective scores. CONCLUSIONS: Based on head-to-head hands-on comparison, endoscopists considered both EMS and PSM credible options for improving understanding and supplementing clinical ERCP training. EMS is more useful for basic learning.

  7. Development and validation of two subject-specific finite element models of human head against three cadaveric experiments.

    PubMed

    Tse, Kwong Ming; Tan, Long Bin; Lee, Shu Jin; Lim, Siak Piang; Lee, Heow Pueh

    2014-03-01

    Head injury, being one of the main causes of death or permanent disability, continues to remain a major health problem with significant socioeconomic costs. Numerical simulations using the FEM offer a cost-effective method and alternative to experimental methods in the biomechanical studies of head injury. The present study aimed to develop two realistic subject-specific FEMs of the human head with detailed anatomical features from medical images (Model 1: without soft tissue and Model 2: with soft tissue and differentiation of white and gray matters) and to validate them against the intracranial pressure (ICP) and relative intracranial motion data of the three cadaver experimental tests. In general, both the simulated results were in reasonably good agreement with the experimental measured ICP and relative displacements, despite slight discrepancy in a few neutral density targets markers. Sensitivity analysis showed some variations in the brain's relative motion to the material properties or marker's location. The addition of soft tissue in Model 2 helped to damp out the oscillations of the model response. It was also found that, despite the fundamental anatomical differences between the two models, there existed little evident differences in the predicted ICP and relative displacements of the two models. This indicated that the advancements on the details of the extracranial features would not improve the model's predicting capabilities of brain injury.

  8. Steroid therapy and the risk of osteonecrosis in SARS patients: a dose-response meta-analysis.

    PubMed

    Zhao, R; Wang, H; Wang, X; Feng, F

    2017-03-01

    This meta-analysis synthesized current evidence from 10 trials to evaluate the association between steroid therapy and osteonecrosis incidence in patients with severe acute respiratory syndrome (SARS). Our results suggest that higher cumulative doses and longer treatment durations of steroids are more likely to lead to the development of osteonecrosis in SARS patients.

  9. Monte Carlo modeling of light propagation in the human head for applications in sinus imaging

    NASA Astrophysics Data System (ADS)

    Cerussi, Albert E.; Mishra, Nikhil; You, Joon; Bhandarkar, Naveen; Wong, Brian

    2015-03-01

    Sinus blockages are a common reason for physician visits, affecting one out of seven people in the United States, and often require medical treatment. Diagnosis in the primary care setting is challenging because symptom criteria (via detailed clinical history) plus objective imaging [computed tomography (CT) or endoscopy] are recommended. Unfortunately, neither option is routinely available in primary care. We previously demonstrated that low-cost near-infrared (NIR) transillumination correlates with the bulk findings of sinus opacity measured by CT. We have upgraded the technology, but questions of source optimization, anatomical influence, and detection limits remain. In order to begin addressing these questions, we have modeled NIR light propagation inside a three-dimensional adult human head constructed via CT images using a mesh-based Monte Carlo algorithm (MMCLAB). In this application, the sinus itself, which when healthy is a void region (e.g., nonscattering), is the region of interest. We characterize the changes in detected intensity due to clear (i.e., healthy) versus blocked sinuses and the effect of illumination patterns. We ran simulations for two clinical cases and compared simulations with measurements. The simulations presented herein serve as a proof of concept that this approach could be used to understand contrast mechanisms and limitations of NIR sinus imaging.

  10. Monte Carlo modeling of light propagation in the human head for applications in sinus imaging

    PubMed Central

    Cerussi, Albert E.; Mishra, Nikhil; You, Joon; Bhandarkar, Naveen; Wong, Brian

    2015-01-01

    Abstract. Sinus blockages are a common reason for physician visits, affecting one out of seven people in the United States, and often require medical treatment. Diagnosis in the primary care setting is challenging because symptom criteria (via detailed clinical history) plus objective imaging [computed tomography (CT) or endoscopy] are recommended. Unfortunately, neither option is routinely available in primary care. We previously demonstrated that low-cost near-infrared (NIR) transillumination correlates with the bulk findings of sinus opacity measured by CT. We have upgraded the technology, but questions of source optimization, anatomical influence, and detection limits remain. In order to begin addressing these questions, we have modeled NIR light propagation inside a three-dimensional adult human head constructed via CT images using a mesh-based Monte Carlo algorithm (MMCLAB). In this application, the sinus itself, which when healthy is a void region (e.g., nonscattering), is the region of interest. We characterize the changes in detected intensity due to clear (i.e., healthy) versus blocked sinuses and the effect of illumination patterns. We ran simulations for two clinical cases and compared simulations with measurements. The simulations presented herein serve as a proof of concept that this approach could be used to understand contrast mechanisms and limitations of NIR sinus imaging. PMID:25781310

  11. Experimental investigation on a high head model Francis turbine during load rejection

    NASA Astrophysics Data System (ADS)

    Goyal, R.; Bergan, C.; Cervantes, M. J.; Gandhi, B. K.; Dahlhaug, O. G.

    2016-11-01

    Francis-99 is a set of workshop aiming to determine the state of the art of high head model Francis turbine simulations (flow and structure) under steady and transient operating conditions as well as to promote their development and knowledge dissemination openly. The first workshop (Trondheim, 2014) was concerned with steady state operation. The second workshop will focus on transient operations such as load variation and start-stop. In the present work, 2-D particle image velocimetry (PIV) with synchronized pressure measurements performed in the draft tube cone of the Francis-99 test case during load rejection is presented. Pressure sensors were mounted in the vaneless space and draft tube cone to estimate the instantaneous pressure fluctuations while operating the turbine from the best efficiency point (9.8°) to part load (6.7°) with the presence of a rotating vortex rope (RVR). The time-resolved velocity and pressure data are presented in this paper showing the transition in the turbine from one state to another.

  12. A Model for Perineural Invasion in Head and Neck Squamous Cell Carcinoma.

    PubMed

    Huyett, Phillip; Gilbert, Mark; Liu, Lijun; Ferris, Robert L; Kim, Seungwon

    2017-01-05

    Perineural invasion (PNI) is found in approximately 40% of head and neck squamous cell carcinomas (HNSCC). Despite multimodal treatment with surgery, radiation, and chemotherapy, locoregional recurrences and distant metastases occur at higher rates, and overall survival is decreased by 40% compared to HNSCC without PNI. In vitro studies of the pathways involved in HNSCC PNI have historically been challenging given the lack of a consistent, reproducible assay. Described here is the adaptation of the dorsal root ganglion (DRG) assay for the examination of PNI in HNSCC. In this model, DRG are harvested from the spinal column of a sacrificed nude mouse and placed within a semisolid matrix. Over the subsequent days, neurites are generated and grow in a radial pattern from the cell bodies of the DRG. HNSCC cell lines are then placed peripherally around the matrix and invade preferentially along the neurites toward the DRG. This method allows for rapid evaluation of multiple treatment conditions, with very high assay success rates and reproducibility.

  13. Real-Time Head Pose Estimation Using a WEBCAM: Monocular Adaptive View-Based Appearance Model

    DTIC Science & Technology

    2008-12-01

    Huang (2006). Graph embedded analysis for head pose estimation. In Proc. IEEE Intl. Conf. Automatic Face and Gesture Recognition , pp. 3–8. Fu, Y. and T...of human- computer and human-robot interaction. Possible appli- cations include novel computer input devices (Fu and Huang, 2007), head gesture ... recognition , driver fatigue recognition systems (Baker et al., 2004), attention aware- ness for intelligent tutoring systems, and social interac- tion

  14. Alendronate-associated osteonecrosis of the jaws: A review of the main topics

    PubMed Central

    Paiva-Fonseca, Felipe; Santos-Silva, Alan R.; Della-Coletta, Ricardo; Vargas, Pablo A.

    2014-01-01

    Bisphosphonates is a group of inorganic pyrophosphates analogues that suppress bone resorption by inducing osteoclast inactivation, being frequently used for management of diseases affecting bone metabolism, bone metastases and bone tumors. However, since 2003 many cases describing the presence of necrotic bone exposures in the jaws have been described in patients receiving these drugs, what represent a significant complication of bisphosphonates treatment. The overall incidence of bisphosphonate-related osteonecrosis of the jaws is low, ranging from 0.7% to 12%, mainly observed in those patients receiving intravenously treatment. Osteonecrosis of the jaws associated to oral bisphosphonate, particularly alendronate, has also been reported by a number of authors. Considering that alendronate is one of the most used drugs worldwide, specially for treatment of osteoporosis, a better understanding of osteonecrosis of the jaws related to its use and how to manage these patients is extremely important. Therefore, in the current manuscript the authors aim to review the most important topics related to this pathological presentation. Key words:Bisphosphonates, alendronate, bisphosphonate-related osteonecrosis of the jaws, osteonecrosis. PMID:23986020

  15. Osteonecrosis of the Jaw in Patients Receiving Bone-Targeted Therapies: An Overview--Part I.

    PubMed

    Turner, Bruce; Drudge-Coates, Lawrence; Ali, Sacha; Pati, Jhumur; Nargund, Vinod; Ali, Enamul; Cheng, Leo; Wells, Paula

    2016-01-01

    Urologic patients receiving bone-targeted therapies are at risk of developing osteonecrosis of the jaw (ONJ). ONJ has historically been associated with bisphosphonate therapy. More recently, RANK-Ligand inhibitors (denosumab) have also been used to reduce the risk of skeletal-related events in patients who have advanced cancers with bone metastases. More than 65% of men with metastatic prostate cancer and nearly 75% of women with metastatic breast cancer are affected by bone metastases. The literature has described ONJ associated with bisphosphonate therapy as bisphosphonate-related osteonecrosis of the jaw (BRONJ). However, with evidence also linking the use of RANK-Ligand inhibitors with osteonecrosis of the jaw, we advocate use of the term "anti-bone resorption therapy-related osteonecrosis of the jaw" (ABRT-ONJ). The term "medication-related osteonecrosis of the jaw" (MRONJ) is now becoming more widespread. There is not a universally accepted definition of ABRT-ONJ, which may have hindered recognition and reporting of the condition. In Part I of this article, a review of current knowledge around the etiology of ABRT-ONJ and incidence data are provided. In Part II, we provide an audit of ONJ in a nurse consultant-led bone support clinic. In the article, we refer to zoledronic acid because this is the bisphosphonate of choice for use in men with prostate cancer in the United Kingdom.

  16. Design of a Kaplan turbine for a wide range of operating head -Curved draft tube design and model test verification-

    NASA Astrophysics Data System (ADS)

    KO, Pohan; MATSUMOTO, Kiyoshi; OHTAKE, Norio; DING, Hua

    2016-11-01

    As for turbomachine off-design performance improvement is challenging but critical for maximising the performing area. In this paper, a curved draft tube for a medium head Kaplan type hydro turbine is introduced and discussed for its significant effect on expanding operating head range. Without adding any extra structure and working fluid for swirl destruction and damping, a carefully designed outline shape of draft tube with the selected placement of center-piers successfully supresses the growth of turbulence eddy and the transport of the swirl to the outlet. Also, more kinetic energy is recovered and the head lost is improved. Finally, the model test results are also presented. The obvious performance improvement was found in the lower net head area, where the maximum efficiency improvement was measured up to 20% without compromising the best efficiency point. Additionally, this design results in a new draft tube more compact in size and so leads to better construction and manufacturing cost performance for prototype. The draft tube geometry parameter designing process was concerning the best efficiency point together with the off-design points covering various water net heads and discharges. The hydraulic performance and flow behavior was numerically previewed and visualized by solving Reynolds-Averaged Navier-Stokes equations with Shear Stress Transport turbulence model. The simulation was under the assumption of steady-state incompressible turbulence flow inside the flow passage, and the inlet boundary condition was the carefully simulated flow pattern from the runner outlet. For confirmation, the corresponding turbine efficiency performance of the entire operating area was verified by model test.

  17. Development of a Novel Markov Chain Model for the Prediction of Head and Neck Squamous Cell Carcinoma Dissemination

    PubMed Central

    Jung, Hyunggu; Law, Anthony; Grunblatt, Eli; Wang, Lucy L.; Kusano, Aaron; Mejino, Jose L. V.; Whipple, Mark E.

    2016-01-01

    Prediction of microscopic tumor spread to regional lymph nodes can assist in radiation planning for cancer treatment. However, it is still challenging to predict tumor spread. In this paper, we present a unique approach to modeling how tumor cells disseminate to form regional metastases. This involves leveraging well established knowledge resources and commonly held notions of how cancer spreads. Using patient data, we utilized our approach to create a model of metastasis for the subset of head and neck squamous cell carcinoma that arises in the mucosa of the lateral tongue. The model was created using a training set extracted from the clinical records of 50 patients with tumors of this type who presented to the University of Washington head and tumor board over a three and half year period. The test sets consist of four case series drawn from the literature. PMID:28269942

  18. Investigation of traumatic brain injuries using the next generation of simulated injury monitor (SIMon) finite element head model.

    PubMed

    Takhounts, Erik G; Ridella, Stephen A; Hasija, Vikas; Tannous, Rabih E; Campbell, J Quinn; Malone, Dan; Danelson, Kerry; Stitzel, Joel; Rowson, Steve; Duma, Stefan

    2008-11-01

    The objective of this study was to investigate potential for traumatic brain injuries (TBI) using a newly developed, geometrically detailed, finite element head model (FEHM) within the concept of a simulated injury monitor (SIMon). The new FEHM is comprised of several parts: cerebrum, cerebellum, falx, tentorium, combined pia-arachnoid complex (PAC) with cerebro-spinal fluid (CSF), ventricles, brainstem, and parasagittal blood vessels. The model's topology was derived from human computer tomography (CT) scans and then uniformly scaled such that the mass of the brain represents the mass of a 50th percentile male's brain (1.5 kg) with the total head mass of 4.5 kg. The topology of the model was then compared to the preliminary data on the average topology derived from Procrustes shape analysis of 59 individuals. Material properties of the various parts were assigned based on the latest experimental data. After rigorous validation of the model using neutral density targets (NDT) and pressure data, the stability of FEHM was tested by loading it simultaneously with translational (up to 400 g) combined with rotational (up to 24,000 rad/s2) acceleration pulses in both sagittal and coronal planes. Injury criteria were established in the manner shown in Takhounts et al. (2003a). After thorough validation and injury criteria establishment (cumulative strain damage measure--CSDM for diffuse axonal injuries (DAI), relative motion damage measure--RMDM for acute subdural hematoma (ASDH), and dilatational damage measure--DDM for contusions and focal lesions), the model was used in investigation of mild TBI cases in living humans based on a set of head impact data taken from American football players at the collegiate level. It was found that CSDM and especially RMDM correlated well with angular acceleration and angular velocity. DDM was close to zero for most impacts due to their mild severity implying that cavitational pressure anywhere in the brain was not reached. Maximum

  19. Feasibility of Primary Tumor Culture Models and Preclinical Prediction Assays for Head and Neck Cancer: A Narrative Review

    PubMed Central

    Dohmen, Amy J. C.; Swartz, Justin E.; Van Den Brekel, Michiel W. M.; Willems, Stefan M.; Spijker, René; Neefjes, Jacques; Zuur, Charlotte L.

    2015-01-01

    Primary human tumor culture models allow for individualized drug sensitivity testing and are therefore a promising technique to achieve personalized treatment for cancer patients. This would especially be of interest for patients with advanced stage head and neck cancer. They are extensively treated with surgery, usually in combination with high-dose cisplatin chemoradiation. However, adding cisplatin to radiotherapy is associated with an increase in severe acute toxicity, while conferring only a minor overall survival benefit. Hence, there is a strong need for a preclinical model to identify patients that will respond to the intended treatment regimen and to test novel drugs. One of such models is the technique of culturing primary human tumor tissue. This review discusses the feasibility and success rate of existing primary head and neck tumor culturing techniques and their corresponding chemo- and radiosensitivity assays. A comprehensive literature search was performed and success factors for culturing in vitro are debated, together with the actual value of these models as preclinical prediction assay for individual patients. With this review, we aim to fill a gap in the understanding of primary culture models from head and neck tumors, with potential importance for other tumor types as well. PMID:26343729

  20. Lithospheric flexure and sedimentary basin evolution: depositional cycles in the steer's head model

    NASA Astrophysics Data System (ADS)

    Moore, James; Watts, Tony

    2016-04-01

    Backstripping studies of biostratigraphic data from deep wells show that sediment loading is one of the main factors controlling the subsidence and uplift history of sedimentary basins. Previous studies based on single layer models of elastic and viscoelastic plates overlying an inviscid fluid have shown that sediment loading, together with a tectonic subsidence that decreases exponentially with time, can explain the large-scale 'architecture' of rift-type basins and, in some cases, details of their internal stratigraphy such as onlap and offlap patterns. One problem with these so-called 'steer's head' models is that they were based on a simple rheological model in which the long-term strength of the lithosphere increased with thermal age. Recent oceanic flexure studies, however, reveal that the long-term strength of the lithosphere depends not only on thermal age, but also load age. We have used the thermal structure based on plate cooling models, together with recent experimentally-derived flow laws, to compute the viscosity structure of the lithosphere and a new analytical model to compute the flexure of a multilayer viscoelastic plate by a trapezoid-shaped sediment load at different times since basin initiation. The combination of basin subsidence and viscoelastic flexural response results in the fluctuation of the depositional surface with time. If we define the nondimensional number Dw= τm/τt, where τm is the Maxwell time constant and τt is the thermal time constant, we find that for Dw<<1 the flexure approximates that of an elastic plate and is dominated by "onlapping" stratigraphy which evolves through the sedimentary facies with a progressive deepening of the depositional surface. For Dw>>1 the flexure approximates that of a viscoelastic plate and is dominated by "offlapping" stratigraphy, with the basin edges evolving through shallow marine facies; though erosion late in the basin formation prevents much of this from being recorded in the stratigraphy

  1. Head MRI

    MedlinePlus

    ... the head; MRI - cranial; NMR - cranial; Cranial MRI; Brain MRI; MRI - brain; MRI - head ... the test, tell your provider if you have: Brain aneurysm clips An artificial heart valves Heart defibrillator ...

  2. Head Injuries

    MedlinePlus

    ... scalp internal head injuries, which may involve the skull, the blood vessels within the skull, or the brain Fortunately, most childhood falls or ... knock the brain into the side of the skull or tear blood vessels. Some internal head injuries ...

  3. Heads Up

    MedlinePlus

    ... Us HEADS UP Apps Reshaping the Culture Around Concussion in Sports Get HEADS UP on Your Web Site Concussion ... fit, and maintain the right helmet for specific sports. Concussion Laws Learn about Return to Play and other ...

  4. Emulating the visual receptive-field properties of MST neurons with a template model of heading estimation

    NASA Technical Reports Server (NTRS)

    Perrone, J. A.; Stone, L. S.

    1998-01-01

    We have proposed previously a computational neural-network model by which the complex patterns of retinal image motion generated during locomotion (optic flow) can be processed by specialized detectors acting as templates for specific instances of self-motion. The detectors in this template model respond to global optic flow by sampling image motion over a large portion of the visual field through networks of local motion sensors with properties similar to those of neurons found in the middle temporal (MT) area of primate extrastriate visual cortex. These detectors, arranged within cortical-like maps, were designed to extract self-translation (heading) and self-rotation, as well as the scene layout (relative distances) ahead of a moving observer. We then postulated that heading from optic flow is directly encoded by individual neurons acting as heading detectors within the medial superior temporal (MST) area. Others have questioned whether individual MST neurons can perform this function because some of their receptive-field properties seem inconsistent with this role. To resolve this issue, we systematically compared MST responses with those of detectors from two different configurations of the model under matched stimulus conditions. We found that the characteristic physiological properties of MST neurons can be explained by the template model. We conclude that MST neurons are well suited to support self-motion estimation via a direct encoding of heading and that the template model provides an explicit set of testable hypotheses that can guide future exploration of MST and adjacent areas within the superior temporal sulcus.

  5. Head lice.

    PubMed

    Frankowski, Barbara L; Weiner, Leonard B

    2002-09-01

    Head lice infestation is associated with little morbidity but causes a high level of anxiety among parents of school-aged children. This statement attempts to clarify issues of diagnosis and treatment of head lice and makes recommendations for dealing with head lice in the school setting.

  6. Rheumatoid Arthritis Exacerbates the Severity of Osteonecrosis of the Jaws (ONJ) in Mice. A Randomized, Prospective, Controlled Animal Study.

    PubMed

    de Molon, Rafael Scaf; Hsu, Chingyun; Bezouglaia, Olga; Dry, Sarah M; Pirih, Flavia Q; Soundia, Akrivoula; Cunha, Fernando Queiroz; Cirelli, Joni Augusto; Aghaloo, Tara L; Tetradis, Sotirios

    2016-08-01

    Rheumatoid arthritis (RA), an autoimmune inflammatory disorder, results in persistent synovitis with severe bone and cartilage destruction. Bisphosphonates (BPs) are often utilized in RA patients to reduce bone destruction and manage osteoporosis. However, BPs, especially at high doses, are associated with osteonecrosis of the jaw (ONJ). Here, utilizing previously published ONJ animal models, we are exploring interactions between RA and ONJ incidence and severity. DBA1/J mice were divided into four groups: control, zoledronic acid (ZA), collagen-induced arthritis (CIA), and CIA-ZA. Animals were pretreated with vehicle or ZA. Bovine collagen II emulsified in Freund's adjuvant was injected to induce arthritis (CIA) and the mandibular molar crowns were drilled to induce periapical disease. Vehicle or ZA treatment continued for 8 weeks. ONJ indices were measured by micro-CT (µCT) and histological examination of maxillae and mandibles. Arthritis development was assessed by visual scoring of paw swelling, and by µCT and histology of interphalangeal and knee joints. Maxillae and mandibles of control and CIA mice showed bone loss, periodontal ligament (PDL) space widening, lamina dura loss, and cortex thinning. ZA prevented these changes in both ZA and CIA-ZA groups. Epithelial to alveolar crest distance was increased in the control and CIA mice. This distance was preserved in ZA and CIA-ZA animals. Empty osteocytic lacunae and areas of osteonecrosis were present in ZA and CIA-ZA but more extensively in CIA-ZA animals, indicating more severe ONJ. CIA and CIA-ZA groups developed severe arthritis in the paws and knees. Interphalangeal and knee joints of CIA mice showed advanced bone destruction with cortical erosions and trabecular bone loss, and ZA treatment reduced these effects. Importantly, no osteonecrosis was noted adjacent to areas of articular inflammation in CIA-ZA mice. Our data suggest that ONJ burden was more pronounced in ZA treated CIA mice and that RA could

  7. Testosterone, anastrozole, factor V Leiden heterozygosity and osteonecrosis of the jaws.

    PubMed

    Pandit, Ramesh S; Glueck, Charles J

    2014-04-01

    Our specific aim is to describe the development of thrombotic osteonecrosis of the jaws after testosterone-anastrozole therapy in a 55-year-old white man subsequently found to have previously undiagnosed factor V Leiden heterozygosity. Before the diagnosis of V Leiden heterozygosity, he was given testosterone gel, 50 mg/day, and on testosterone, serum testosterone (963 ng/dl) and estradiol were high (50 pg/ml). Anastrozole was started, and testosterone was continued. Six months later, osteonecrosis of the jaws was diagnosed. Exogenous testosterone is aromatized to estradiol and estradiol-induced thrombophilia, when superimposed on underlying familial thrombophilia, as in this case, may lead to thrombosis and osteonecrosis. We recommend that before giving testosterone, at a minimum, screening for the factor V Leiden and G20210A mutations, and factor VIII and XI activity be carried out, to avoid unanticipated thrombosis.

  8. Using hip measures to avoid misdiagnosing early rapid onset osteoarthritis for osteonecrosis.

    PubMed

    Nelson, Fred R T; Bhandarkar, Varun S; Woods, Tammy A

    2014-06-01

    In the early phases, subchondral insufficiency fractures and rapidly destructive osteoarthritis of the hip are often mistaken for osteonecrosis of the hip. Three hip measures were used comparing combined subchondral insufficiency fractures and rapidly destructive 18 osteoarthritis patients to 18 osteonecrosis patients. Due to the rarity of these conditions there was no statistical power. Initial diagnoses for the osteoarthritis patients were recorded. The osteoarthritis group had significantly higher means for Tönnis angle (P < 0.001), lateral center edge angle (P = 0.006), and acetabular extrusion index (P = 0.014). Only 7 of the 18 patients were initially diagnosed without reservation as subchondral insufficiency fracture or rapidly destructive osteoarthritis. Using hip measures will reduce the misdiagnosis of rapid onset osteoarthritis of the hip for osteonecrosis.

  9. Modeling of ray paths of head waves on irregular interfaces in TOFD inspection for NDE.

    PubMed

    Ferrand, A; Darmon, M; Chatillon, S; Deschamps, M

    2014-09-01

    The TOFD (Time of Flight Diffraction) technique is a classical ultrasonic inspection method used in ultrasonic non-destructive evaluation (NDE). This inspection technique is based on an arrangement of two probes of opposite beam directions and allows a precise positioning and a quantitative evaluation of the size of cracks contained in the inspected material thanks to their edges diffraction echoes. Among the typical phenomena arising for such an arrangement, head waves, which propagate along the specimen surface and are chronologically the first waves reaching the receiver, are notably observed. Head wave propagation on planar surfaces in TOFD configurations is well known. However, realistic inspection configurations often involve components with irregular surfaces, like steel excavated specimens. Surface irregularity is responsible for numerous effects on the scattering of bulk waves, causing the melting of surface and bulk mechanisms in the head wave propagation. In order to extend the classical ray approach on these complex cases, a generic algorithm of ray tracing between interface points (GIRT) has been designed. With respect to time of flight minimization (i.e. the Generalized Fermat's Principle), ray paths can be computed by GIRT for different natures of waves scattered by the complex surfaces or by flaws. The head wave fronts computed by GIRT are notably in good agreement with FEM simulated results. This algorithm, based on pure kinematic analysis of waves propagation, represents a first step in the future development of a complete ray theory for head waves simulation on irregular interfaces.

  10. Modelling an advanced ManPAD with dual band detectors and a rosette scanning seeker head

    NASA Astrophysics Data System (ADS)

    Birchenall, Richard P.; Richardson, Mark A.; Butters, Brian; Walmsley, Roy

    2012-01-01

    Man Portable Air Defence Systems (ManPADs) have been a favoured anti aircraft weapon since their appearance on the military proliferation scene in the mid 1960s. Since this introduction there has been a 'cat and mouse' game of Missile Countermeasures (CMs) and the aircraft protection counter counter measures (CCMs) as missile designers attempt to defeat the aircraft platform protection equipment. Magnesium Teflon Viton (MTV) flares protected the target aircraft until the missile engineers discovered the art of flare rejection using techniques including track memory and track angle bias. These early CCMs relied upon CCM triggering techniques such as the rise rate method which would just sense a sudden increase in target energy and assume that a flare CM had been released by the target aircraft. This was not as reliable as was first thought as aspect changes (bringing another engine into the field of view) or glint from the sun could inadvertently trigger a CCM when not needed. The introduction of dual band detectors in the 1980s saw a major advance in CCM capability allowing comparisons between two distinct IR bands to be made thus allowing the recognition of an MTV flare to occur with minimal false alarms. The development of the rosette scan seeker in the 1980s complemented this advancement allowing the scene in the missile field of view (FOV) to be scanned by a much smaller (1/25) instantaneous FOV (IFOV) with the spectral comparisons being made at each scan point. This took the ManPAD from a basic IR energy detector to a pseudo imaging system capable of analysing individual elements of its overall FOV allowing more complex and robust CCM to be developed. This paper continues the work published in [1,2] and describes the method used to model an advanced ManPAD with a rosette scanning seeker head and robust CCMs similar to the Raytheon Stinger RMP.

  11. Two-Year versus One-Year Head Start Program Impact: Addressing Selection Bias by Comparing Regression Modeling with Propensity Score Analysis

    ERIC Educational Resources Information Center

    Leow, Christine; Wen, Xiaoli; Korfmacher, Jon

    2015-01-01

    This article compares regression modeling and propensity score analysis as different types of statistical techniques used in addressing selection bias when estimating the impact of two-year versus one-year Head Start on children's school readiness. The analyses were based on the national Head Start secondary dataset. After controlling for…

  12. Genetics of glucocorticoid-associated osteonecrosis in children with acute lymphoblastic leukemia.

    PubMed

    Karol, Seth E; Yang, Wenjian; Van Driest, Sara L; Chang, Tamara Y; Kaste, Sue; Bowton, Erica; Basford, Melissa; Bastarache, Lisa; Roden, Dan M; Denny, Joshua C; Larsen, Eric; Winick, Naomi; Carroll, William L; Cheng, Cheng; Pei, Deqing; Fernandez, Christian A; Liu, Chengcheng; Smith, Colton; Loh, Mignon L; Raetz, Elizabeth A; Hunger, Stephen P; Scheet, Paul; Jeha, Sima; Pui, Ching-Hon; Evans, William E; Devidas, Meenakshi; Mattano, Leonard A; Relling, Mary V

    2015-10-08

    Glucocorticoids are important therapy for acute lymphoblastic leukemia (ALL) and their major adverse effect is osteonecrosis. Our goal was to identify genetic and nongenetic risk factors for osteonecrosis. We performed a genome-wide association study of single nucleotide polymorphisms (SNPs) in a discovery cohort comprising 2285 children with ALL, treated on the Children's Oncology Group AALL0232 protocol (NCT00075725), adjusting for covariates. The minor allele at SNP rs10989692 (near the glutamate receptor GRIN3A locus) was associated with osteonecrosis (hazard ratio = 2.03; P = 3.59 × 10(-7)). The association was supported by 2 replication cohorts, including 361 children with ALL on St. Jude's Total XV protocol (NCT00137111) and 309 non-ALL patients from Vanderbilt University's BioVU repository treated with glucocorticoids (odds ratio [OR] = 1.87 and 2.26; P = .063 and .0074, respectively). In a meta-analysis, rs10989692 was also highest ranked (P = 2.68 × 10(-8)), and the glutamate pathway was the top ranked pathway (P = 9.8 × 10(-4)). Osteonecrosis-associated glutamate receptor variants were also associated with other vascular phenotypes including cerebral ischemia (OR = 1.64; P = 2.5 × 10(-3)), and arterial embolism and thrombosis (OR = 1.88; P = 4.2 × 10(-3)). In conclusion, osteonecrosis was associated with inherited variations near glutamate receptor genes. Further understanding this association may allow interventions to decrease osteonecrosis. These trials are registered at www.clinicaltrials.gov as #NCT00075725 and #NCT00137111.

  13. A new posture-correcting system using a vector angle model for preventing forward head posture

    PubMed Central

    Yeom, Hojun; Lim, Juhun; Yoo, Sung Hak; Lee, Woocheol

    2014-01-01

    In modern society many people are afflicted with muscle pain in the neck and shoulders mainly caused by incorrect posture. The number of patients having neck pain is increasing as usage of digital devices becomes more frequent. If patients could be notified how inappropriate their postures are in real time, the number of patients could be lower. Unfortunately, there is no digitized standard way of diagnosis for forward head posture. This study applies a concept based on a vector related to two angles which are acquired from the neck and the head, so that a device can diagnose the posture by measuring and analysing the angles. To obtain the vector, integral calculations of displacement of the head are needed. As a result, with this device, patients’ faulty posture can be easily detected. PMID:26019611

  14. A Fully Nonlinear, Dynamically Consistent Numerical Model for Solid-Body Ship Motion. 1. Ship Motion with Fixed Heading

    DTIC Science & Technology

    2010-01-01

    various ship hulls for heave, roll and pitch motion. In addition to the benchmark cases, numerical experiments are also carried out for strongly...Uy and Uz are called roll , pitch and yaw, respectively. In the model reference frame the x-axis is the ship heading direction (from the stern to the...unsteady ship motions ( roll , pitch and heave) are compared and cross-examined. Reported here are selected cases, which are the extreme scenarios of the

  15. Head impact accelerations for brain strain-related responses in contact sports: a model-based investigation.

    PubMed

    Ji, Songbai; Zhao, Wei; Li, Zhigang; McAllister, Thomas W

    2014-10-01

    Both linear [Formula: see text] and rotational [Formula: see text] accelerations contribute to head impacts on the field in contact sports; however, they are often isolated in injury studies. It is critical to evaluate the feasibility of estimating brain responses using isolated instead of full degrees-of-freedom (DOFs) accelerations. In this study, we investigated the sensitivities of regional brain strain-related responses to resultant [Formula: see text] and [Formula: see text] as well as the relative contributions of these acceleration components to the responses via random sampling and linear regression using parameterized, triangulated head impacts with kinematic variable values based on on-field measurements. Two independently established and validated finite element models of the human head were employed to evaluate model-consistency and dependency in results: the Dartmouth Head Injury Model and Simulated Injury Monitor. For the majority of the brain, volume-weighted regional peak strain, strain rate, and von Mises stress accumulated from the simulation significantly correlated with the product of the magnitude and duration of [Formula: see text], or effectively, the rotational velocity, but not to [Formula: see text]. Responses from [Formula: see text]-only were comparable to the full-DOF counterparts especially when normalized by injury-causing thresholds (e.g., volume fractions of large differences virtually diminished (i.e., [Formula: see text]1 %) at typical difference percentage levels of 1-4 % on average). These model-consistent results support the inclusion of both rotational acceleration magnitude and duration into kinematics-based injury metrics and demonstrate the feasibility of estimating strain-related responses from isolated [Formula: see text] for analyses of strain-induced injury relevant to contact sports without significant loss of accuracy, especially for the cerebrum.

  16. Woodpeckers and head injury.

    PubMed

    May, P R; Fuster, J M; Newman, P; Hirschman, A

    1976-02-28

    The woodpecker is an experiment in Nature, a model for the investigation of mechanisms of basic importance for head injury and its prevention. A preliminary anatomical study of the woodpecker's head suggests that it may be fruitful to explore impact protective systems which are radically different from those in common use.

  17. Should all anticoagulated patients with head injury receive a CT scan? Decision-analysis modelling of an observational cohort

    PubMed Central

    Kuczawski, Maxine; Stevenson, Matt; Goodacre, Steve; Teare, M Dawn; Ramlakhan, Shammi; Morris, Francis; Mason, Suzanne

    2016-01-01

    Objectives It is not currently clear whether all anticoagulated patients with a head injury should receive CT scanning or only those with evidence of traumatic brain injury (eg, loss of consciousness or amnesia). We aimed to determine the cost-effectiveness of CT for all compared with selective CT use for anticoagulated patients with a head injury. Design Decision-analysis modelling of data from a multicentre observational study. Setting 33 emergency departments in England and Scotland. Participants 3566 adults (aged ≥16 years) who had suffered blunt head injury, were taking warfarin and underwent selective CT scanning. Main outcome measures Estimated expected benefits in terms of quality-adjusted life years (QALYs) were the entire cohort to receive a CT scan; estimated increased costs of CT and also the potential cost implications associated with patient survival and improved health. These values were used to estimate the cost per QALY of implementing a strategy of CT for all patients compared with observed practice based on guidelines recommending selective CT use. Results Of the 1420 of 3534 patients (40%) who did not receive a CT scan, 7 (0.5%) suffered a potentially avoidable head injury-related adverse outcome. If CT scanning had been performed in all patients, appropriate treatment could have gained 3.41 additional QALYs but would have incurred £193 149 additional treatment costs and £130 683 additional CT costs. The incremental cost-effectiveness ratio of £94 895/QALY gained for unselective compared with selective CT use is markedly above the threshold of £20–30 000/QALY used by the UK National Institute for Care Excellence to determine cost-effectiveness. Conclusions CT scanning for all anticoagulated patients with head injury is not cost-effective compared with selective use of CT scanning based on guidelines recommending scanning only for those with evidence of traumatic brain injury. Trial registration number NCT 02461498. PMID

  18. Numerical calculation of listener-specific head-related transfer functions and sound localization: Microphone model and mesh discretization.

    PubMed

    Ziegelwanger, Harald; Majdak, Piotr; Kreuzer, Wolfgang

    2015-07-01

    Head-related transfer functions (HRTFs) can be numerically calculated by applying the boundary element method on the geometry of a listener's head and pinnae. The calculation results are defined by geometrical, numerical, and acoustical parameters like the microphone used in acoustic measurements. The scope of this study was to estimate requirements on the size and position of the microphone model and on the discretization of the boundary geometry as triangular polygon mesh for accurate sound localization. The evaluation involved the analysis of localization errors predicted by a sagittal-plane localization model, the comparison of equivalent head radii estimated by a time-of-arrival model, and the analysis of actual localization errors obtained in a sound-localization experiment. While the average edge length (AEL) of the mesh had a negligible effect on localization performance in the lateral dimension, the localization performance in sagittal planes, however, degraded for larger AELs with the geometrical error as dominant factor. A microphone position at an arbitrary position at the entrance of the ear canal, a microphone size of 1 mm radius, and a mesh with 1 mm AEL yielded a localization performance similar to or better than observed with acoustically measured HRTFs.

  19. Diagnosis and Staging of Medication-Related Osteonecrosis of the Jaw.

    PubMed

    Ruggiero, Salvatore L

    2015-11-01

    The relationship between osteonecrosis of the jaw and bisphosphonate therapy was initially established more than 10 years ago. Since that time our understanding of this disease process has evolved as the direct result of clinical, basic science, and animal research initiatives. Medication-related osteonecrosis of the jaw (MRONJ) is a well-known entity now known to be associated with various antiresorptive therapies and recently with antiangiogenic medications. This article reviews the recently modified diagnostic criteria for MRONJ with a focus on the clinical, histopathologic, and imaging characteristics of this disease process.

  20. The Frequency of Medication-related Osteonecrosis of the Jaw and its Associated Risk Factors.

    PubMed

    Dodson, Thomas B

    2015-11-01

    This article provides the best current frequency estimate of medication-related osteonecrosis of the jaws (MRONJ), and identifies factors associated with the risk of developing osteonecrosis of the jaw (ONJ) among patients exposed to relevant medications (ie, antiresorptive or antiangiogenic agents). MRONJ is a rare but serious complication of cancer treatment or osteoporosis management. This review confirms that antiresorptive medications such as oral or intravenous bisphosphonates and denosumab are the most common risk factors for developing ONJ. The risk of MRONJ is greater in patients with cancer than in those receiving antiresorptive treatments for osteoporosis by a factor of 10.

  1. Bisphosphonate-related osteonecrosis of the jaw complicated by Ludwig's angina.

    PubMed

    Yang, Rong-Hsin; Shen, Shu-Huei; Li, Wing-Yin; Chu, Yum-Kung

    2015-01-01

    Ludwig's angina is a life-threatening cellulitis that involves the submandibular and sublingual spaces. It often occurs after an infection of the roots of the teeth. However, modern dental care and use of antibiotics for oral infections have made Ludwig's angina rare. We present here a cancer patient exhibiting the sequential features of bisphosphonate related osteonecrosis of the jaw on bone scan complicating with Ludwig's angina. This report highlights the need for medical practitioners to be alert to these rare combinations in the compromised patient after bisphosphonate therapy. To the best of our knowledge, no case of Ludwig's angina secondary to osteonecrosis of the jaw has been reported.

  2. Histopathologic findings of spontaneous osteonecrosis of the knee at an early stage: a case report.

    PubMed

    Hatanaka, Hiroyuki; Yamamoto, Takuaki; Motomura, Goro; Sonoda, Kazuhiko; Iwamoto, Yukihide

    2016-05-01

    We histopathologically examined a surgically resected full specimen obtained from an early-stage spontaneous osteonecrosis of the knee (SPONK). On a mid-coronal cut section of the resected medial femoral condyle, a linear fracture line paralleling the subchondral bone endplate was found. Histopathologically, prominent callus formation was seen comprising of reactive woven bone and granulation tissue on both sides of the fracture. Fracture-related bone debris was focally observed at the osteochondral side of the fracture. Definitive features of antecedent bone infarction such as creeping substitution and bone marrow necrosis were not detected. These findings suggested that SPONK was the result of a subchondral fracture rather than primary osteonecrosis.

  3. ANTIBIOTIC EFFECTS ON BACTERIAL PROFILE IN OSTEONECROSIS OF THE JAW

    PubMed Central

    Ji, Xiaojie; Pushalkar, Smruti; Li, Yihong; Glickman, Robert; Fleisher, Kenneth; Saxena, Deepak

    2011-01-01

    OBJECTIVE Oral infection is considered to play a critical role in the pathogenesis of bisphosphonate-related osteonecrosis of the jaw (BRONJ) and antibiotic therapy has become a mainstay of BRONJ therapy. This study was aimed to investigate the effect of antibiotics on bacterial diversity in BRONJ tissues. MATERIALS AND METHODS The bacterial profile from soft tissues associated with the BRONJ lesion was determined using 16S rRNA-based denaturing gradient gel electrophoresis (DGGE) and sequencing. Twenty BRONJ subjects classified as stage 0 to 2 were enrolled in this study and patient groups were divided into an antibiotic cohort (n=10) treated with systemic antibiotic and a non-antibiotic cohort (n=10) with no prior antibiotic therapy. RESULTS The DGGE fingerprints indicated no significant differences in bacterial diversity of BRONJ tissue samples. Patients on antibiotics had higher relative abundance of phylum Firmicutes with bacterial species, Streptococcus intermedius, Lactobacillus gasseri, Mogibacterium timidum and Solobacterium moorei whereas patients without antibiotics had greater amounts of Parvimonas micra, and S. anginosus. Thirty percent of bacterial populations were uncultured (yet-to be cultured) phylotypes. CONCLUSION This study using limited sample size indicated that oral antibiotic therapy may have a limited efficacy on the bacterial population associated with BRONJ lesions. PMID:21883710

  4. Osteonecrosis of the jaw associated with everolimus: A case report

    PubMed Central

    Yamamoto, Daigo; Tsubota, Yu; Utsunomiya, Toshiki; Sueoka, Noriko; Ueda, Aiko; Endo, Kayoko; Yoshikawa, Katsuhiro; Kon, Masanori

    2017-01-01

    Everolimus, a mammalian target of rapamycin inhibitor, has recently been approved for the treatment of metastatic estrogen receptor-positive breast cancer, at a daily dose of 10 mg in combination with exemestane. Osteonecrosis of the jaw (ONJ) is a rare but severe condition, characterized by exposed necrotic bone, and is associated with various drugs that are often used to treat advanced malignancies. We herein report the case of a patient with breast cancer who developed ONJ during treatment with everolimus, which improved after discontinuation of the drug. To the best of our knowledge, this is the first reported case of everolimus-associated ONJ in a patient receiving everolimus for metastatic breast cancer. In 2014, an 80-year-old woman was started on treatment with everolimus and exemestane for stage IIB estrogen receptor-positive breast cancer. Within 2 months, the left side of her face became edematous, with localized heat and tenderness of the left mandibular region and a 3-mm round area of exposed bone. There was purulent discharge and the surrounding gingiva was edematous and erythematous. The left mandible exhibited a low signal intensity area on T1-weighted magnetic resonance imaging. Treatment was discontinued and ONJ showed improvement after 2 months. Therefore, when prescribing everolimus for metastatic breast cancer, oncologists should be aware of the possibility of ONJ as a complication. PMID:28357105

  5. Intracranial Electrical Impedance Tomography: A Method of Continuous Monitoring in an Animal Model of Head Trauma

    PubMed Central

    Manwaring, Preston K.; Moodie, Karen L.; Hartov, Alexander; Manwaring, Kim H.; Halter, Ryan J.

    2013-01-01

    Background Electrical impedance tomography (EIT) is a method that can render continuous graphical cross-sectional images of the brain’s electrical properties. Because these properties can be altered by variations in water content, shifts in Na+ concentration, bleeding, and mass deformation, EIT has promise as a sensitive instrument for head injury monitoring to improve early recognition of deterioration, and to observe the benefits of therapeutic intervention. This study presents a swine model of head injury used to determine the detection capabilities of an inexpensive bed side EIT monitoring system with a novel intracranial pressure (ICP)/EIT electrode combination sensor on induced intraparenchymal mass effect, intraparenchymal hemorrhage, and cessation of brain blood flow. Conductivity difference images are shown in conjunction with ICP data, confirming the effects. Methods Eight domestic piglets (3–4 weeks old, mean 10kg), under general anesthesia, were subjected to four injuries: induced intraparenchymal mass effect using an inflated, and later, deflated 0.15mL Fogarty catheter; hemorrhage by intraparenchymal injection of 1mL arterial blood; and ischemia/infarction by euthanasia. EIT and ICP data were recorded 10 minutes prior to inducing the injury until 10 minutes post-injury. Continuous EIT and ICP monitoring were facilitated by a ring of circumferentially disposed cranial Ag/AgCl electrodes and one intraparenchymal ICP/EIT sensor-electrode combination. Data were recorded at 100 Hz. Two-dimensional tomographic conductivity difference (Δσ) images, rendered using data before and after an injury, were displayed in real-time on an axial circular mesh. Regions of interest (ROI) within the images were automatically selected as the upper or lower 5% of conductivity data depending upon the nature of the injury. Mean Δσ within the ROIs and background were statistically analyzed. ROI Δσ was compared to the background Δσ after an injury event using an

  6. Construction of a biomechanical head and neck motion model as a guide to evaluation of deformable image registration.

    PubMed

    Teske, Hendrik; Bartelheimer, Kathrin; Meis, Jan; Bendl, Rolf; Stoiber, Eva; Giske, Kristina

    2017-03-28

    The use of deformable image registration methods in the context of adaptive radiotherapy leads to uncertainties in the simulation of the administered dose distributions during the treatment course. Evaluation of these methods is a prerequisite to decide if a plan adaptation will improve the individual treatment. Current approaches using manual references limit the validity of evaluation, especially for low contrast regions. In particular for the head and neck region, the highly flexible anatomy and the low soft tissue contrast in control images pose a challenge to image registration and its evaluation. Biomechanical models promise to overcome this issue by providing anthropomorphic motion modelling of the patient. We introduce a novel biomechanical motion model for generation and sampling of different postures of the head and neck anatomy. Motion propagation behaviour of the individual bones is defined by an underlying kinematic model. This model interconnects the bones by joints and thus is capable to provide a wide range of motion. Triggered by the motion of the individual bones, soft tissue deformation is described by an extended heterogeneous tissue model based on the chainmail approach. This extension, for the first time, allows the propagation of decaying rotations within soft tissue without the necessity of explicit tissue segmentation. Overall motion simulation and sampling of deformed CT scans including a basic noise model is achieved within 30 seconds. The proposed biomechanical motion model for the head and neck site generates displacement vector fields on a voxel basis, approximating arbitrary anthropomorphic postures of the patient. It was developed with the intention to provide input data for the evaluation of deformable image registration.

  7. Rotating and translating anthropomorphic head voxel models to establish an horizontal Frankfort plane for dental CBCT Monte Carlo simulations: a dose comparison study

    NASA Astrophysics Data System (ADS)

    Stratis, A.; Zhang, G.; Jacobs, R.; Bogaerts, R.; Bosmans, H.

    2016-12-01

    In order to carry out Monte Carlo (MC) dosimetry studies, voxel phantoms, modeling human anatomy, and organ-based segmentation of CT image data sets are applied to simulation frameworks. The resulting voxel phantoms preserve patient CT acquisition geometry; in the case of head voxel models built upon head CT images, the head support with which CT scanners are equipped introduces an inclination to the head, and hence to the head voxel model. In dental cone beam CT (CBCT) imaging, patients are always positioned in such a way that the Frankfort line is horizontal, implying that there is no head inclination. The orientation of the head is important, as it influences the distance of critical radiosensitive organs like the thyroid and the esophagus from the x-ray tube. This work aims to propose a procedure to adjust head voxel phantom orientation, and to investigate the impact of head inclination on organ doses in dental CBCT MC dosimetry studies. The female adult ICRP, and three in-house-built paediatric voxel phantoms were in this study. An EGSnrc MC framework was employed to simulate two commonly used protocols; a Morita Accuitomo 170 dental CBCT scanner (FOVs: 60  ×  60 mm2 and 80  ×  80 mm2, standard resolution), and a 3D Teeth protocol (FOV: 100  ×  90 mm2) in a Planmeca Promax 3D MAX scanner. Result analysis revealed large absorbed organ dose differences in radiosensitive organs between the original and the geometrically corrected voxel models of this study, ranging from  -45.6% to 39.3%. Therefore, accurate dental CBCT MC dose calculations require geometrical adjustments to be applied to head voxel models.

  8. A model of head-related transfer functions based on a state-space analysis

    NASA Astrophysics Data System (ADS)

    Adams, Norman Herkamp

    This dissertation develops and validates a novel state-space method for binaural auditory display. Binaural displays seek to immerse a listener in a 3D virtual auditory scene with a pair of headphones. The challenge for any binaural display is to compute the two signals to supply to the headphones. The present work considers a general framework capable of synthesizing a wide variety of auditory scenes. The framework models collections of head-related transfer functions (HRTFs) simultaneously. This framework improves the flexibility of contemporary displays, but it also compounds the steep computational cost of the display. The cost is reduced dramatically by formulating the collection of HRTFs in the state-space and employing order-reduction techniques to design efficient approximants. Order-reduction techniques based on the Hankel-operator are found to yield accurate low-cost approximants. However, the inter-aural time difference (ITD) of the HRTFs degrades the time-domain response of the approximants. Fortunately, this problem can be circumvented by employing a state-space architecture that allows the ITD to be modeled outside of the state-space. Accordingly, three state-space architectures are considered. Overall, a multiple-input, single-output (MISO) architecture yields the best compromise between performance and flexibility. The state-space approximants are evaluated both empirically and psychoacoustically. An array of truncated FIR filters is used as a pragmatic reference system for comparison. For a fixed cost bound, the state-space systems yield lower approximation error than FIR arrays for D>10, where D is the number of directions in the HRTF collection. A series of headphone listening tests are also performed to validate the state-space approach, and to estimate the minimum order N of indiscriminable approximants. For D = 50, the state-space systems yield order thresholds less than half those of the FIR arrays. Depending upon the stimulus uncertainty, a

  9. Deformation Prediction and Geometrical Modeling of Head and Neck Cancer Tumor: A Data Mining Approach

    NASA Astrophysics Data System (ADS)

    Azimi, Maryam

    Radiation therapy has been used in the treatment of cancer tumors for several years and many cancer patients receive radiotherapy. It may be used as primary therapy or with a combination of surgery or other kinds of therapy such as chemotherapy, hormone therapy or some mixture of the three. The treatment objective is to destroy cancer cells or shrink the tumor by planning an adequate radiation dose to the desired target without damaging the normal tissues. By using the pre-treatment Computer Tomography (CT) images, most of the radiotherapy planning systems design the target and assume that the size of the tumor will not change throughout the treatment course, which takes 5 to 7 weeks. Based on this assumption, the total amount of radiation is planned and fractionated for the daily dose required to be delivered to the patient's body. However, this assumption is flawed because the patients receiving radiotherapy have marked changes in tumor geometry during the treatment period. Therefore, there is a critical need to understand the changes of the tumor shape and size over time during the course of radiotherapy in order to prevent significant effects of inaccuracy in the planning. In this research, a methodology is proposed in order to monitor and predict daily (fraction day) tumor volume and surface changes of head and neck cancer tumors during the entire treatment period. In the proposed method, geometrical modeling and data mining techniques will be used rather than repetitive CT scans data to predict the tumor deformation for radiation planning. Clinical patient data were obtained from the University of Texas-MD Anderson Cancer Center (MDACC). In the first step, by using CT scan data, the tumor's progressive geometric changes during the treatment period are quantified. The next step relates to using regression analysis in order to develop predictive models for tumor geometry based on the geometric analysis results and the patients' selected attributes (age, weight

  10. Models of Emotion Skills and Social Competence in the Head Start Classroom

    ERIC Educational Resources Information Center

    Spritz, Becky L.; Sandberg, Elisabeth Hollister; Maher, Edward; Zajdel, Ruth T.

    2010-01-01

    Research Findings: Fostering the social competence of at-risk preschoolers would be facilitated by knowing which of children's emotion skills are most salient to social outcomes. We examined the emotion skills and social competence of 44 children enrolled in a Head Start program. Emotion skills were examined in terms of children's emotional…

  11. Parenting Classes, Parenting Behavior, and Child Cognitive Development in Early Head Start: A Longitudinal Model

    ERIC Educational Resources Information Center

    Chang, Mido; Park, Boyoung; Kim, Sunha

    2009-01-01

    This study analyzed Early Head Start Research and Evaluation (EHSRE) study data, examining the effect of parenting classes on parenting behaviors and children's cognitive outcomes. The study analyzed three sets of dependent variables: parental language and cognitive stimulation, parent-child interactive activities, and the Bayley Mental…

  12. Tumor-Volume Simulation During Radiotherapy for Head-and-Neck Cancer Using a Four-Level Cell Population Model

    SciTech Connect

    Chvetsov, Alexei V. Dong Lei; Palta, Jantinder R.; Amdur, Robert J.

    2009-10-01

    Purpose: To develop a fast computational radiobiologic model for quantitative analysis of tumor volume during fractionated radiotherapy. The tumor-volume model can be useful for optimizing image-guidance protocols and four-dimensional treatment simulations in proton therapy that is highly sensitive to physiologic changes. Methods: The analysis is performed using two approximations: (1) tumor volume is a linear function of total cell number and (2) tumor-cell population is separated into four subpopulations: oxygenated viable cells, oxygenated lethally damaged cells, hypoxic viable cells, and hypoxic lethally damaged cells. An exponential decay model is used for disintegration and removal of oxygenated lethally damaged cells from the tumor. Results: We tested our model on daily volumetric imaging data available for 14 head-and-neck cancer patients treated with an integrated computed tomography/linear accelerator system. A simulation based on the averaged values of radiobiologic parameters was able to describe eight cases during the entire treatment and four cases partially (50% of treatment time) with a maximum 20% error. The largest discrepancies between the model and clinical data were obtained for small tumors, which may be explained by larger errors in the manual tumor volume delineation procedure. Conclusions: Our results indicate that the change in gross tumor volume for head-and-neck cancer can be adequately described by a relatively simple radiobiologic model. In future research, we propose to study the variation of model parameters by fitting to clinical data for a cohort of patients with head-and-neck cancer and other tumors. The potential impact of other processes, like concurrent chemotherapy, on tumor volume should be evaluated.

  13. Modelling the Species Distribution of Flat-Headed Cats (Prionailurus planiceps), an Endangered South-East Asian Small Felid

    PubMed Central

    Hearn, Andrew J.; Hesse, Deike; Mohamed, Azlan; Traeholdt, Carl; Cheyne, Susan M.; Sunarto, Sunarto; Jayasilan, Mohd-Azlan; Ross, Joanna; Shapiro, Aurélie C.; Sebastian, Anthony; Dech, Stefan; Breitenmoser, Christine; Sanderson, Jim; Duckworth, J. W.; Hofer, Heribert

    2010-01-01

    Background The flat-headed cat (Prionailurus planiceps) is one of the world's least known, highly threatened felids with a distribution restricted to tropical lowland rainforests in Peninsular Thailand/Malaysia, Borneo and Sumatra. Throughout its geographic range large-scale anthropogenic transformation processes, including the pollution of fresh-water river systems and landscape fragmentation, raise concerns regarding its conservation status. Despite an increasing number of camera-trapping field surveys for carnivores in South-East Asia during the past two decades, few of these studies recorded the flat-headed cat. Methodology/Principal Findings In this study, we designed a predictive species distribution model using the Maximum Entropy (MaxEnt) algorithm to reassess the potential current distribution and conservation status of the flat-headed cat. Eighty-eight independent species occurrence records were gathered from field surveys, literature records, and museum collections. These current and historical records were analysed in relation to bioclimatic variables (WorldClim), altitude (SRTM) and minimum distance to larger water resources (Digital Chart of the World). Distance to water was identified as the key predictor for the occurrence of flat-headed cats (>50% explanation). In addition, we used different land cover maps (GLC2000, GlobCover and SarVision LLC for Borneo), information on protected areas and regional human population density data to extract suitable habitats from the potential distribution predicted by the MaxEnt model. Between 54% and 68% of suitable habitat has already been converted to unsuitable land cover types (e.g. croplands, plantations), and only between 10% and 20% of suitable land cover is categorised as fully protected according to the IUCN criteria. The remaining habitats are highly fragmented and only a few larger forest patches remain. Conclusion/Significance Based on our findings, we recommend that future conservation efforts for

  14. Development, Implementation, and Validation of Supported Employment Model(s) for Traumatically Brain Injured Persons. Head Injury Re-entry Project (Project HIRe). Final Report.

    ERIC Educational Resources Information Center

    Thomas, Dale F.; Menz, Fredrick E.

    The final report of the Head Injury Re-entry Project (Project HIRe) describes activities of this 3-year (1987 to 1990) project, which used a "best practices" model approach and a community-based employment strategy with persons having traumatic brain injury (TBI) in nonurban areas. Among 15 project accomplishments are the following: (1)…

  15. Improving inferences from short-term ecological studies with Bayesian hierarchical modeling: white-headed woodpeckers in managed forests.

    PubMed

    Linden, Daniel W; Roloff, Gary J

    2015-08-01

    Pilot studies are often used to design short-term research projects and long-term ecological monitoring programs, but data are sometimes discarded when they do not match the eventual survey design. Bayesian hierarchical modeling provides a convenient framework for integrating multiple data sources while explicitly separating sample variation into observation and ecological state processes. Such an approach can better estimate state uncertainty and improve inferences from short-term studies in dynamic systems. We used a dynamic multistate occupancy model to estimate the probabilities of occurrence and nesting for white-headed woodpeckers Picoides albolarvatus in recent harvest units within managed forests of northern California, USA. Our objectives were to examine how occupancy states and state transitions were related to forest management practices, and how the probabilities changed over time. Using Gibbs variable selection, we made inferences using multiple model structures and generated model-averaged estimates. Probabilities of white-headed woodpecker occurrence and nesting were high in 2009 and 2010, and the probability that nesting persisted at a site was positively related to the snag density in harvest units. Prior-year nesting resulted in higher probabilities of subsequent occurrence and nesting. We demonstrate the benefit of forest management practices that increase the density of retained snags in harvest units for providing white-headed woodpecker nesting habitat. While including an additional year of data from our pilot study did not drastically alter management recommendations, it changed the interpretation of the mechanism behind the observed dynamics. Bayesian hierarchical modeling has the potential to maximize the utility of studies based on small sample sizes while fully accounting for measurement error and both estimation and model uncertainty, thereby improving the ability of observational data to inform conservation and management strategies.

  16. Improving inferences from short-term ecological studies with Bayesian hierarchical modeling: white-headed woodpeckers in managed forests

    PubMed Central

    Linden, Daniel W; Roloff, Gary J

    2015-01-01

    Pilot studies are often used to design short-term research projects and long-term ecological monitoring programs, but data are sometimes discarded when they do not match the eventual survey design. Bayesian hierarchical modeling provides a convenient framework for integrating multiple data sources while explicitly separating sample variation into observation and ecological state processes. Such an approach can better estimate state uncertainty and improve inferences from short-term studies in dynamic systems. We used a dynamic multistate occupancy model to estimate the probabilities of occurrence and nesting for white-headed woodpeckers Picoides albolarvatus in recent harvest units within managed forests of northern California, USA. Our objectives were to examine how occupancy states and state transitions were related to forest management practices, and how the probabilities changed over time. Using Gibbs variable selection, we made inferences using multiple model structures and generated model-averaged estimates. Probabilities of white-headed woodpecker occurrence and nesting were high in 2009 and 2010, and the probability that nesting persisted at a site was positively related to the snag density in harvest units. Prior-year nesting resulted in higher probabilities of subsequent occurrence and nesting. We demonstrate the benefit of forest management practices that increase the density of retained snags in harvest units for providing white-headed woodpecker nesting habitat. While including an additional year of data from our pilot study did not drastically alter management recommendations, it changed the interpretation of the mechanism behind the observed dynamics. Bayesian hierarchical modeling has the potential to maximize the utility of studies based on small sample sizes while fully accounting for measurement error and both estimation and model uncertainty, thereby improving the ability of observational data to inform conservation and management strategies

  17. Modeling the effect of head drag reduction for a cylinder with a protruding disk at high mach numbers

    NASA Astrophysics Data System (ADS)

    Isaev, S. A.; Baranov, P. A.; Mikhalev, A. N.; Sudakov, A. G.

    2014-11-01

    Various approaches to modeling super- and hypersonic turbulent airflow past cylindrical bodies with a nontraditional nose in the form of a protruding rod-supported disk have been compared. Aeroballistic experiments on a light-gas propulsion setup were combined with wind tunnel tests and numerical simulations using VP2/3 program package based on multiblock computational techniques and a model of shear stress transport with flow-line curvature corrections. The phenomenon of the head and wave drag reduction for the stepped body is analyzed at high Mach numbers (up to 10) and variation of the supporting rod length under conditions of existence of the frontal flow separation zone.

  18. Head Injuries

    MedlinePlus

    ... injury, cerebral contusion, cerebral laceration, coma, head trauma, hematoma, impaired consciousness, postconcussion syndrome, skull fracture, skull penetration, stupor, vegetative state Family Health, Infants ...

  19. Identification of differentially expressed microRNAs involved in non-traumatic osteonecrosis through microRNA expression profiling.

    PubMed

    Wu, Xingjing; Zhang, Yongtao; Guo, Xiong; Xu, Hongguang; Xu, Zhujun; Duan, Dapeng; Wang, Kunzheng

    2015-07-01

    Accumulating evidence has recently indicated a vital role of microRNAs (miRNAs) in the development of various bone diseases. However, the biological role of miRNAs in the pathogenesis of non-traumatic osteonecrosis of femoral head (ONFH) has not yet been investigated. The present study aimed to profile the differential miRNA expression between non-traumatic ONFH and femoral neck fracture and to develop further understanding of the molecular mechanisms involved in the pathogenesis of non-traumatic ONFH. Femoral heads from 4 patients with non-traumatic ONFH and 4 with femoral neck fracture were used to analyze the miRNA expression profiles in bone tissue using the Exiqon miRCURY™ LNA Array (v.18.0). The results of miRNA microarray analysis were further confirmed by real-time quantitative polymerase chain reaction (qPCR). The differentially expressed miRNA target genes and signaling pathways involved were predicted by bioinformatics analysis. MiRNA microarray chip analysis revealed that 22 miRNAs were significantly up-regulated and 17 were significantly down-regulated in the non-traumatic ONFH samples compared with the femoral neck fracture samples. The real-time qPCR also confirmed the microarray data. Bioinformatics analysis demonstrated that toll-like receptor (TLR), neurotrophin and NOD-like receptor signaling pathway were most likely to be regulated by these differential miRNAs. This miRNA microarray study reveals significant differences in miRNA expression between patients with non-traumatic ONFH and those with femoral neck fracture. Our data also manifests that the signaling pathways regulated by these differentially expressed miRNAs might be important in the pathogenesis of non-traumatic ONFH.

  20. Intraarticular corticosteroids possibly leading to local osteonecrosis and marrow fat induced synovitis.

    PubMed

    McCarty, D J; McCarthy, G; Carrera, G

    1991-07-01

    We describe a woman with recurrent synovitis in one or both knees treated with intraarticular corticosteroid injections and two 6-day courses of methylprednisolone tablets. She later developed osteonecrosis of her distal femora and proximal tibiae. Her course was complicated by persistent synovitis associated with a large quantity of necrotic fat in the joint fluid.

  1. Bisphosphonates, vitamin D, parathyroid hormone, and osteonecrosis of the jaw. Could there be a missing link?

    PubMed Central

    Leizaola-Cardesa, Ignacio-Osoitz; Aguilar-Salvatierra, Antonio; Gonzalez-Jaranay, Maximino; Moreu, Gerardo; Sala-Romero, María-José

    2016-01-01

    It is estimated that over 190 million bisphosphonates have been prescribed worldwide. But this drug can produce adverse effects, of which osteonecrosis of the jaw and severe hypocalcemia are the most serious. It is evident that bisphosphonate administration affects multiple and diverse biochemical mediators related to bone metabolism. This review of literature investigates four basic parameters in patients treated with bisphosphonates - parathyroid hormone (PTH), bisphosphonates, vitamin D, calcium, and jaw osteonecrosis - which are fundamental for assessing bone metabolism and so the efficacy and correct use of the drug. The imbalances generated by vitamin D and calcium deficiencies, together with their multiple systemic repercussions, have been widely researched but the outcomes of these imbalances in relation to bisphosphonate administration are not well known, and some research has indicated that they may be associated with osteonecrosis of the jaw (ONJ). The present review set out to explain the functioning of bone metabolism, the importance of different chemical mediators, the imbalances produced by incorrect use of this drug, in order to forewarn against the possible relation of these parameters with ONJ, whose physiopathology remains unknown. Medical and dental clinics should keep detailed anamneses of the use of vitamin D and calcium supplements, as it is of vital importance to maintain their correct levels in blood, given that these are related to ONJ as well as other adverse effects; this procedure is also necessary in order to ensure the correct use of the drug. Key words:Bisphosphonate-related osteonecrosis of the jaw, vitamin D, parathyroid hor PMID:26827062

  2. Immunologically augmented skin flap as a novel dendritic cell vaccine against head and neck cancer in a rat model.

    PubMed

    Inoue, Keita; Saegusa, Noriko; Omiya, Maho; Ashizawa, Tadashi; Miyata, Haruo; Komiyama, Masaru; Iizuka, Akira; Kume, Akiko; Sugino, Takashi; Yamaguchi, Ken; Kiyohara, Yoshio; Nakagawa, Masahiro; Akiyama, Yasuto

    2015-02-01

    Local recurrence is a major clinical issue following surgical resection in head and neck cancer, and the dissemination and lymph node metastasis of minimal residual disease is relatively difficult to treat due to the lack of suitable therapeutic approaches. In the present study, we developed and evaluated a novel immunotherapy using a skin flap transfer treated with sensitized dendritic cells (DC), termed the "immuno-flap," in a rat tumor model. After the local round area of skin was resected, SCC-158 cells (a rat head and neck cancer cell line) were inoculated into the muscle surface; lastly, the groin skin flap injected with mature DC was overlaid. Two weeks after the second DC injection, systemic immunological reactions and tumor size were measured. The DC-treated group showed a significant reduction in tumor size compared with the control. Although the induction of CTL activity in spleen cells was marginal, Th1 cytokines such as interleukin-2 and interferon-γ were elevated in the DC-treated group. These results suggest that a novel immunotherapy based on the immuno-flap method has the potential for clinical application to prevent the local recurrence of head and neck cancer patients.

  3. Impact of head models in N170 component source imaging: results in control subjects and ADHD patients

    NASA Astrophysics Data System (ADS)

    Beltrachini, L.; Blenkmann, A.; von Ellenrieder, N.; Petroni, A.; Urquina, H.; Manes, F.; Ibáñez, A.; Muravchik, C. H.

    2011-12-01

    The major goal of evoked related potential studies arise in source localization techniques to identify the loci of neural activity that give rise to a particular voltage distribution measured on the surface of the scalp. In this paper we evaluate the effect of the head model adopted in order to estimate the N170 component source in attention deficit hyperactivity disorder (ADHD) patients and control subjects, considering faces and words stimuli. The standardized low resolution brain electromagnetic tomography algorithm (sLORETA) is used to compare between the three shell spherical head model and a fully realistic model based on the ICBM-152 atlas. We compare their variance on source estimation and analyze the impact on the N170 source localization. Results show that the often used three shell spherical model may lead to erroneous solutions, specially on ADHD patients, so its use is not recommended. Our results also suggest that N170 sources are mainly located in the right occipital fusiform gyrus for faces stimuli and in the left occipital fusiform gyrus for words stimuli, for both control subjects and ADHD patients. We also found a notable decrease on the N170 estimated source amplitude on ADHD patients, resulting in a plausible marker of the disease.

  4. Animated visualization of a high resolution color three dimensional digital computer model of the whole human head.

    PubMed

    Narayan, S; Sensharma, D; Santori, E M; Lee, A A; Sabherwal, A; Toga, A W

    1993-01-01

    The interactive visualization of animated images through a computerized three dimensional (3D) full color model of an unstained cadaveric human head is presented. Serial full color images were taken of the blockface of a cryomicrotomed frozen human head every 200 microns. From this series of images a three dimensional digital model with a resultant pixel resolution of 200 microns3 was created on a UNIX workstation. Using this database, resampled images were computed along orthogonal axes and written sequentially to a write-once-read-many times (WORM) videodisc unit. Playback of this customized videodisc dataset provides animations of the digitally reconstructed slices and 3D reconstructed surface models. An interactive interface to the animated sequences is provided through a PC based tutorial package. This tutorial program is able to access videodisc frames to display animations and labeled still images in a software window to illustrate various neuroanatomic topics. The technique of animation as applied to this high resolution 3D model provides insight into complex spatial relationships and has great potential in research and as a teaching tool in the neurosciences.

  5. The role of cerebral spinal fluid in light propagation through the mouse head: improving fluorescence tomography with Monte Carlo modeling

    NASA Astrophysics Data System (ADS)

    Ancora, Daniele; Zacharopoulos, Athanasios; Ripoll, Jorge; Zacharakis, Giannis

    2016-03-01

    Optical Neuroimaging is a highly dynamical field of research owing to the combination of many advanced imaging techniques and computational tools that uncovered unexplored paths through the functioning of the brain. Light propagation modelling through such complicated structures has always played a crucial role as the basis for a high resolution and quantitative imaging where even the slightest improvement could lead to significant results. Fluorescence Diffuse Optical Tomography (fDOT), a widely used technique for three dimensional imaging of small animals and tissues, has been proved to be inaccurate for neuroimaging the mouse head without the knowledge of a-priori anatomical information of the subject. Commonly a normalized Born approximation model is used in fDOT reconstruction based on forward photon propagation using Diffusive Equation (DE) which has strong limitations in the optically clear regime. The presence of the Cerebral Spinal Fluid (CSF) instead, a thin optically clear layer surrounding the brain, can be more accurately taken into account using Monte Carlo approaches which nowadays is becoming more usable thanks to parallelized GPU algorithms. In this work we discuss the results of a synthetic experimental comparison, resulting to the increase of the accuracy for the Born approximation by introducing the CSF layer in a realistic mouse head structure with respect to the current model. We point out the importance of such clear layer for complex geometrical models, while for simple slab phantoms neglecting it does not introduce a significant error.

  6. Concept, diagnosis and classification of bisphosphonate-associated osteonecrosis of the jaws. A review of the literature

    PubMed Central

    Bagan, Jose V.

    2016-01-01

    Background Bisphosphonates (BPs) and other antiresorptive agents such as denosumab are widely prescribed for the treatment of osteoporosis and are also used in patients with multiple myeloma and metastatic breast or prostate cancer for avoiding bone reabsorption and fractures that result in increased morbidity-mortality among such individuals. Material and Methods We made a bibliographic search to analyze the concept, diagnosis and the different classifications for bisphosphonate-associated osteonecrosis of the jaws. Results Osteonecrosis of the jaws (ONJ) is an important complication of exposure to BPs or other antiresorptive agents, and although its prevalence is low, it can pose management problems. The definition, diagnosis and classification of osteonecrosis have evolved since Marx reported the first cases in 2003. Conclusions The present study offers a literature review and update on the existing diagnostic methods and classification of the disorder, with a view to facilitating earlier and more effective treatment. Key words:Osteonecrosis, jaws, bisphosphonates. PMID:26827066

  7. Osteonecrosis of the Torus Palatinus in the Setting of Long-Term Oral Bisphosphonate Use--A Case Report.

    PubMed

    Ryan, Joshua L; Larson, Eric

    2016-01-01

    Bisphosphonates are medications used orally and intravenously for a variety of conditions including cancer metastatic to bone, hypercalcemia of malignancy, Paget's disease and osteoporosis. Osteonecrosis of the jaw has been related to bisphosphonate use. Osteonecrosis of the jaw most commonly occurs in the setting of intravenous bisphosphonate use and concomitant dental work or trauma. Oral bisphosphonates have much less risk of osteonecrosis of the jaw. We present an interesting case of a patient on an oral bisphosphonate for an extended period of time (nine years), with a torus palatinus, who burned her palate while eating a slice of pizza. Over six months later, she presented with an area of denuded bone and diagnosis consistent with osteonecrosis of the torus palatinus.

  8. Minimum-norm cortical source estimation in layered head models is robust against skull conductivity error☆☆☆

    PubMed Central

    Stenroos, Matti; Hauk, Olaf

    2013-01-01

    The conductivity profile of the head has a major effect on EEG signals, but unfortunately the conductivity for the most important compartment, skull, is only poorly known. In dipole modeling studies, errors in modeled skull conductivity have been considered to have a detrimental effect on EEG source estimation. However, as dipole models are very restrictive, those results cannot be generalized to other source estimation methods. In this work, we studied the sensitivity of EEG and combined MEG + EEG source estimation to errors in skull conductivity using a distributed source model and minimum-norm (MN) estimation. We used a MEG/EEG modeling set-up that reflected state-of-the-art practices of experimental research. Cortical surfaces were segmented and realistically-shaped three-layer anatomical head models were constructed, and forward models were built with Galerkin boundary element method while varying the skull conductivity. Lead-field topographies and MN spatial filter vectors were compared across conductivities, and the localization and spatial spread of the MN estimators were assessed using intuitive resolution metrics. The results showed that the MN estimator is robust against errors in skull conductivity: the conductivity had a moderate effect on amplitudes of lead fields and spatial filter vectors, but the effect on corresponding morphologies was small. The localization performance of the EEG or combined MEG + EEG MN estimator was only minimally affected by the conductivity error, while the spread of the estimate varied slightly. Thus, the uncertainty with respect to skull conductivity should not prevent researchers from applying minimum norm estimation to EEG or combined MEG + EEG data. Comparing our results to those obtained earlier with dipole models shows that general judgment on the performance of an imaging modality should not be based on analysis with one source estimation method only. PMID:23639259

  9. 3D Numerical modeling and its experimental verifications for an inhomogeneous head phantom using broadband fNIR system.

    PubMed

    Sultan, E; Pourrezaei, K; Ghandjbakhche, A; Daryoush, A S

    2014-03-01

    Modeling behavior of broadband (30-1000 MHz) frequency modulated near infrared photons through a multilayer phantom is of interest to optical bio-imaging research. Photon dynamics in phantom are predicted using three-dimension (3D) finite element numerical simulation and are related to the measured insertion loss and phase for a given human head geometry in this paper based on three layers of phantom each with distinct optical parameter properties. Simulation and experimental results are achieved for single, two, and three layers solid phantoms using COMSOL (COMSOL AB, Tegnérgatan 23, SE-111 40, Stockholm, Sweden) (for FEM) simulation and custom-designed broadband free space optical transmitter (Tx) and receiver (Rx) modules that are developed for photon migration at wavelengths of 680, 795, and 850 nm. Standard error is used to compute error between two-dimension and 3D FE modeling along with experimental results by fitting experimental data to the functional form of afrequency+b. Error results are shown at narrowband and broadband frequency modulation. Confidence in numerical modeling of the photonic behavior using 3D FEM for human head has been established here by comparing the reflection mode's experimental results with the predictions made by COMSOL for known commercial solid brain phantoms.

  10. Temporal and Spatial Weighting of Head and Concentration Observations for a Large-Scale Transient Inverse Model

    SciTech Connect

    Scheibe, Timothy D.; Murray, Christopher J.; Xie, YuLong; Williams, Mark D.; Cole, Charles R.; Vermeul, Vince R.; Bergeron, Marcel P.

    2003-09-19

    A regional-scale, three-dimensional groundwater flow and transport modeling effort is ongoing to quantify the environmental consequences of past waste disposal activities and support environmental management activities at the U.S. Department of Energy’s 560-square-mile Hanford Site in southeastern Washington. On the order of one thousand wells in the deep surficial aquifer have been monitored over several decades of site operations (beginning in the 1940’s), and tens of thousands of observations of water table elevation (head) and contaminant concentrations (primarily tritium) have been made over that same period. These data are currently being used as the basis for a site-wide inverse modeling effort to identify model parameters and quantify model uncertainty. Several issues complicate the assignment of appropriate weights to the observations used in the inverse modeling process. The precision of available monitoring techniques has changed significantly over the modeled time period, and the associated error weighting should reflect the methods used (which were in some cases not well documented). In some cases, the detection limits are poorly defined, and some analytical techniques can give rise to non-physical results (such as negative measured concentrations). In addition, the data are strongly clustered both in space and time. This presents the possibility of the inverse solution being too strongly influenced by a cluster of similar values. However, the elimination of some data by declustering techniques, or alternatively, the adjustment of observation weights used in the objective function, raises problems with interpretation and regulatory acceptance of model predictions and uncertainty estimates. This paper presents the methods we have utilized to assign appropriate weights to head and concentration observations and discusses potential issues associated with the weighting scheme employed.

  11. A Novel Closed-Head Model of Mild Traumatic Brain Injury Using Focal Primary Overpressure Blast to the Cranium in Mice

    PubMed Central

    Guley, Natalie H.; Rogers, Joshua T.; Del Mar, Nobel A.; Deng, Yunping; Islam, Rafiqul M.; D'Surney, Lauren; Ferrell, Jessica; Deng, Bowei; Hines-Beard, Jessica; Bu, Wei; Ren, Huiling; Elberger, Andrea J.; Marchetta, Jeffrey G.; Rex, Tonia S.; Honig, Marcia G.

    2016-01-01

    Abstract Mild traumatic brain injury (TBI) from focal head impact is the most common form of TBI in humans. Animal models, however, typically use direct impact to the exposed dura or skull, or blast to the entire head. We present a detailed characterization of a novel overpressure blast system to create focal closed-head mild TBI in mice. A high-pressure air pulse limited to a 7.5 mm diameter area on the left side of the head overlying the forebrain is delivered to anesthetized mice. The mouse eyes and ears are shielded, and its head and body are cushioned to minimize movement. This approach creates mild TBI by a pressure wave that acts on the brain, with minimal accompanying head acceleration-deceleration. A single 20-psi blast yields no functional deficits or brain injury, while a single 25–40 psi blast yields only slight motor deficits and brain damage. By contrast, a single 50–60 psi blast produces significant visual, motor, and neuropsychiatric impairments and axonal damage and microglial activation in major fiber tracts, but no contusive brain injury. This model thus reproduces the widespread axonal injury and functional impairments characteristic of closed-head mild TBI, without the complications of systemic or ocular blast effects or head acceleration that typically occur in other blast or impact models of closed-skull mild TBI. Accordingly, our model provides a simple way to examine the biomechanics, pathophysiology, and functional deficits that result from TBI and can serve as a reliable platform for testing therapies that reduce brain pathology and deficits. PMID:26414413

  12. A Novel Closed-Head Model of Mild Traumatic Brain Injury Using Focal Primary Overpressure Blast to the Cranium in Mice.

    PubMed

    Guley, Natalie H; Rogers, Joshua T; Del Mar, Nobel A; Deng, Yunping; Islam, Rafiqul M; D'Surney, Lauren; Ferrell, Jessica; Deng, Bowei; Hines-Beard, Jessica; Bu, Wei; Ren, Huiling; Elberger, Andrea J; Marchetta, Jeffrey G; Rex, Tonia S; Honig, Marcia G; Reiner, Anton

    2016-02-15

    Mild traumatic brain injury (TBI) from focal head impact is the most common form of TBI in humans. Animal models, however, typically use direct impact to the exposed dura or skull, or blast to the entire head. We present a detailed characterization of a novel overpressure blast system to create focal closed-head mild TBI in mice. A high-pressure air pulse limited to a 7.5 mm diameter area on the left side of the head overlying the forebrain is delivered to anesthetized mice. The mouse eyes and ears are shielded, and its head and body are cushioned to minimize movement. This approach creates mild TBI by a pressure wave that acts on the brain, with minimal accompanying head acceleration-deceleration. A single 20-psi blast yields no functional deficits or brain injury, while a single 25-40 psi blast yields only slight motor deficits and brain damage. By contrast, a single 50-60 psi blast produces significant visual, motor, and neuropsychiatric impairments and axonal damage and microglial activation in major fiber tracts, but no contusive brain injury. This model thus reproduces the widespread axonal injury and functional impairments characteristic of closed-head mild TBI, without the complications of systemic or ocular blast effects or head acceleration that typically occur in other blast or impact models of closed-skull mild TBI. Accordingly, our model provides a simple way to examine the biomechanics, pathophysiology, and functional deficits that result from TBI and can serve as a reliable platform for testing therapies that reduce brain pathology and deficits.

  13. Integrating deterministic lithostratigraphic models in stochastic realizations of subsurface heterogeneity. Impact on predictions of lithology, hydraulic heads and groundwater fluxes

    NASA Astrophysics Data System (ADS)

    Bianchi, Marco; Kearsey, Timothy; Kingdon, Andrew

    2015-12-01

    Realistic representations of geological complexity are important to address several engineering and environmental challenges. The spatial distribution of properties controlling physical and geochemical processes can be effectively described by the geological structure of the subsurface. In this work, we present an approach to account for geological structure in geostatistical simulations of categorical variables. The approach is based on the extraction of information from a deterministic conceptualization of the subsurface, which is then used in the geostatistical analysis for the development of models of spatial correlation and as soft conditioning data. The approach was tested to simulate the distribution of four lithofacies in highly heterolithic Quaternary deposits. A transition probability-based stochastic model was implemented using hard borehole data and soft data extracted from a 3-D deterministic lithostratigraphic model. Simulated lithofacies distributions were also used as input in a flow model for numerical simulation of hydraulic head and groundwater flux. The outputs from these models were compared to corresponding values from models based exclusively on borehole data. Results show that soft lithostratigraphic information increases the accuracy and reduces the uncertainty of these predictions. The representation of the geological structure also allows a more precise definition of the spatial distribution of prediction uncertainty, here quantified with a metric based on Shannon information entropy. Correlations between prediction uncertainties for lithofacies, hydraulic heads and groundwater fluxes were also investigated. The results from this analysis provide useful insights about the incorporation of soft geological data into stochastic realizations of subsurface heterogeneity, and emphasize the critical importance of this type of information for reducing the uncertainty of simulations considering flux-dependent processes.

  14. High Prevalence of Prothrombotic Abnormalities in Multifocal Osteonecrosis

    PubMed Central

    Peris, Pilar; Reverter, Joan Carles; Espinosa, Gerard; Martinez-Ferrer, Angeles; Monegal, Ana; Monteagudo, Juan; Tàssies, Dolors; Guañabens, Nuria

    2013-01-01

    Abstract Multifocal or multiple osteonecrosis (ON), defined by the involvement of 3 or more anatomic sites, is unusual, being observed in only 3%–10% of patients diagnosed with ON. We report the clinical characteristics of a cohort of 29 patients with multifocal ON from a single center and evaluate the prevalence of associated prothrombotic abnormalities in 26 of these patients. We conducted a retrospective study of all patients diagnosed with multifocal ON evaluated in our institution during the last 20 years. We recorded clinical manifestations and underlying diagnoses. A wide thrombophilic profile was performed, including antithrombin, protein C, protein S, lupus anticoagulant, anticardiolipin antibodies, activated protein C resistance, factor V Leiden, mutation G-20210-A of the prothrombin gene, and factor VIII. Coagulation test results were compared with those in a healthy control group and a group of patients with history of lower-extremity deep venous thrombosis. The mean age of the patients was 49.2 ± 15 years (range, 28–81 yr). The mean number of ON localizations per patient was 5.2 ± 2.3 (range, 3–11). Hips were the most commonly affected joint (82%), followed by knees (58%), shoulders (37%), and ankles (13%). Most patients had an underlying disease process, and 12 of 25 (48%) patients had coagulation test abnormalities. The most common alterations were high factor VIII levels and antiphospholipid antibody (aPL) positivity in 24% and 20% of cases, respectively. These abnormalities were more prevalent in patients with multifocal ON compared with patients in the control groups. Sixty-one percent of patients had a history of corticosteroid treatment. Patients with coagulation abnormalities had a higher number of ON localizations per patient (6.5 ± 2.7 vs. 3.88 ± 0.8; p = 0.002) and a higher prevalence of atypical ON localizations (25% vs. 0%; p = 0.05). In conclusion, in the present cohort of patients with multifocal ON, 48% of the patients had at

  15. Normal Tissue Complication Probability Modeling of Radiation-Induced Hypothyroidism After Head-and-Neck Radiation Therapy

    SciTech Connect

    Bakhshandeh, Mohsen; Hashemi, Bijan; Mahdavi, Seied Rabi Mehdi; Nikoofar, Alireza; Vasheghani, Maryam; Kazemnejad, Anoshirvan

    2013-02-01

    Purpose: To determine the dose-response relationship of the thyroid for radiation-induced hypothyroidism in head-and-neck radiation therapy, according to 6 normal tissue complication probability models, and to find the best-fit parameters of the models. Methods and Materials: Sixty-five patients treated with primary or postoperative radiation therapy for various cancers in the head-and-neck region were prospectively evaluated. Patient serum samples (tri-iodothyronine, thyroxine, thyroid-stimulating hormone [TSH], free tri-iodothyronine, and free thyroxine) were measured before and at regular time intervals until 1 year after the completion of radiation therapy. Dose-volume histograms (DVHs) of the patients' thyroid gland were derived from their computed tomography (CT)-based treatment planning data. Hypothyroidism was defined as increased TSH (subclinical hypothyroidism) or increased TSH in combination with decreased free thyroxine and thyroxine (clinical hypothyroidism). Thyroid DVHs were converted to 2 Gy/fraction equivalent doses using the linear-quadratic formula with {alpha}/{beta} = 3 Gy. The evaluated models included the following: Lyman with the DVH reduced to the equivalent uniform dose (EUD), known as LEUD; Logit-EUD; mean dose; relative seriality; individual critical volume; and population critical volume models. The parameters of the models were obtained by fitting the patients' data using a maximum likelihood analysis method. The goodness of fit of the models was determined by the 2-sample Kolmogorov-Smirnov test. Ranking of the models was made according to Akaike's information criterion. Results: Twenty-nine patients (44.6%) experienced hypothyroidism. None of the models was rejected according to the evaluation of the goodness of fit. The mean dose model was ranked as the best model on the basis of its Akaike's information criterion value. The D{sub 50} estimated from the models was approximately 44 Gy. Conclusions: The implemented normal tissue

  16. Depth-compensated diffuse optical tomography enhanced by general linear model analysis and an anatomical atlas of human head.

    PubMed

    Tian, Fenghua; Liu, Hanli

    2014-01-15

    One of the main challenges in functional diffuse optical tomography (DOT) is to accurately recover the depth of brain activation, which is even more essential when differentiating true brain signals from task-evoked artifacts in the scalp. Recently, we developed a depth-compensated algorithm (DCA) to minimize the depth localization error in DOT. However, the semi-infinite model that was used in DCA deviated significantly from the realistic human head anatomy. In the present work, we incorporated depth-compensated DOT (DC-DOT) with a standard anatomical atlas of human head. Computer simulations and human measurements of sensorimotor activation were conducted to examine and prove the depth specificity and quantification accuracy of brain atlas-based DC-DOT. In addition, node-wise statistical analysis based on the general linear model (GLM) was also implemented and performed in this study, showing the robustness of DC-DOT that can accurately identify brain activation at the correct depth for functional brain imaging, even when co-existing with superficial artifacts.

  17. Head Tilt

    MedlinePlus

    ... Throat Emotional Problems Eyes Fever From Insects or Animals Genitals and Urinary Tract Glands & Growth Head Neck & Nervous System Heart Infections Learning Disabilities Obesity Orthopedic Prevention Sexually Transmitted Skin Tobacco ...

  18. Head Noises.

    ERIC Educational Resources Information Center

    Senior, Tom

    2000-01-01

    Explains how a toy called "Sound Bites" can be modified to demonstrate the transmission of sound waves. Students can hear music from the toy when they press it against any bone in their heads or shoulders. (WRM)

  19. Head Injuries

    MedlinePlus

    ... before. Often, the injury is minor because your skull is hard and it protects your brain. But ... injuries can be more severe, such as a skull fracture, concussion, or traumatic brain injury. Head injuries ...

  20. Head lice

    MedlinePlus

    ... make the nits easier to remove. Some dishwashing detergents can help dissolve the "glue" that makes the ... clothes and bed linens in hot water with detergent. This also helps prevent head lice from spreading ...

  1. Head Injuries

    MedlinePlus

    ... won't stop crying complains of head and neck pain (younger or nonverbal children may be more fussy) ... vision pupils of unequal size weakness or paralysis neck pain or stiffness seizure If your child is unconscious: ...

  2. Actively targeted gold nanoparticles as novel radiosensitizer agents: an in vivo head and neck cancer model

    NASA Astrophysics Data System (ADS)

    Popovtzer, Aron; Mizrachi, Aviram; Motiei, Menachem; Bragilovski, Dimitri; Lubimov, Leon; Levi, Mattan; Hilly, Ohad; Ben-Aharon, Irit; Popovtzer, Rachela

    2016-01-01

    A major problem in the treatment of head and neck cancer today is the resistance of tumors to traditional radiation therapy, which results in 40% local failure, despite aggressive treatment. The main objective of this study was to develop a technique which will overcome tumor radioresistance by increasing the radiation absorbed in the tumor using cetuximab targeted gold nanoparticles (GNPs), in clinically relevant energies and radiation dosage. In addition, we have investigated the biological mechanisms underlying tumor shrinkage and the in vivo toxicity of GNP. The results showed that targeted GNP enhanced the radiation effect and had a significant impact on tumor growth (P < 0.001). The mechanism of radiation enhancement was found to be related to earlier and greater apoptosis (TUNEL assay), angiogenesis inhibition (by CD34 level) and diminished repair mechanism (PCNA staining). Additionally, GNPs have been proven to be safe as no evidence of toxicity has been observed.

  3. Influence of Head Motion on the Accuracy of 3D Reconstruction with Cone-Beam CT: Landmark Identification Errors in Maxillofacial Surface Model

    PubMed Central

    Song, Jin-Myoung; Cho, Jin-Hyoung

    2016-01-01

    Purpose The purpose of this study was to investigate the influence of head motion on the accuracy of three-dimensional (3D) reconstruction with cone-beam computed tomography (CBCT) scan. Materials and Methods Fifteen dry skulls were incorporated into a motion controller which simulated four types of head motion during CBCT scan: 2 horizontal rotations (to the right/to the left) and 2 vertical rotations (upward/downward). Each movement was triggered to occur at the start of the scan for 1 second by remote control. Four maxillofacial surface models with head motion and one control surface model without motion were obtained for each skull. Nine landmarks were identified on the five maxillofacial surface models for each skull, and landmark identification errors were compared between the control model and each of the models with head motion. Results Rendered surface models with head motion were similar to the control model in appearance; however, the landmark identification errors showed larger values in models with head motion than in the control. In particular, the Porion in the horizontal rotation models presented statistically significant differences (P < .05). Statistically significant difference in the errors between the right and left side landmark was present in the left side rotation which was opposite direction to the scanner rotation (P < .05). Conclusions Patient movement during CBCT scan might cause landmark identification errors on the 3D surface model in relation to the direction of the scanner rotation. Clinicians should take this into consideration to prevent patient movement during CBCT scan, particularly horizontal movement. PMID:27065238

  4. Validation of CRASH Model in Prediction of 14-day Mortality and 6-month Unfavorable Outcome of Head Trauma Patients

    PubMed Central

    Hashemi, Behrooz; Amanat, Mahnaz; Baratloo, Alireza; Forouzanfar, Mohammad Mehdi; Rahmati, Farhad; Motamedi, Maryam; Safari, Saeed

    2016-01-01

    Introduction: To date, many prognostic models have been proposed to predict the outcome of patients with traumatic brain injuries. External validation of these models in different populations is of great importance for their generalization. The present study was designed, aiming to determine the value of CRASH prognostic model in prediction of 14-day mortality (14-DM) and 6-month unfavorable outcome (6-MUO) of patients with traumatic brain injury. Methods: In the present prospective diagnostic test study, calibration and discrimination of CRASH model were evaluated in head trauma patients referred to the emergency department. Variables required for calculating CRASH expected risks (ER), and observed 14-DM and 6-MUO were gathered. Then ER of 14-DM and 6-MUO were calculated. The patients were followed for 6 months and their 14-DM and 6-MUO were recorded. Finally, the correlation of CRASH ER and the observed outcome of the patients was evaluated. The data were analyzed using STATA version 11.0. Results: In this study, 323 patients with the mean age of 34.0 ± 19.4 years were evaluated (87.3% male). Calibration of the basic and CT models in prediction of 14-day and 6-month outcome were in the desirable range (P < 0.05). Area under the curve in the basic model for prediction of 14-DM and 6-MUO were 0.92 (95% CI: 0.89-0.96) and 0.92 (95% CI: 0.90-0.95), respectively. In addition, area under the curve in the CT model for prediction of 14-DM and 6-MUO were 0.93 (95% CI: 0.91-0.97) and 0.93 (95% CI: 0.91-0.96), respectively. There was no significant difference between the discriminations of the two models in prediction of 14-DM (p = 0.11) and 6-MUO (p = 0.1). Conclusion: The results of the present study showed that CRASH prediction model has proper discrimination and calibration in predicting 14-DM and 6-MUO of head trauma patients. Since there was no difference between the values of the basic and CT models, using the basic model is recommended to simplify the risk

  5. 3D-printed porous titanium changed femoral head repair growth patterns: osteogenesis and vascularisation in porous titanium.

    PubMed

    Zhu, Wei; Zhao, Yan; Ma, Qi; Wang, Yingjie; Wu, Zhihong; Weng, Xisheng

    2017-04-01

    Osteonecrosis of the femoral head (ONFH) is a major cause of morbidity, and total hip arthroplasty is both traumatic and expensive. Here, we created a gelatine scaffold embedded in uniquely shaped, 3D-printed porous titanium parts, which could attract and promote the proliferation of osteoblasts as well as bone regeneration, as the extracellular matrix (ECM) does in vivo. Interestingly, after hybridisation with platelets, the scaffold exhibited a low yet considerable rate of stable, safe and long-term growth factor release. Additionally, a novel ONFH model was constructed and verified. Scaffolds implanted in this model were found to accelerate bone repair. In conclusion, our scaffold successfully simulates the ECM and considerably accelerates bone regeneration, in which platelets play an indispensable role. We believe that platelets should be emphasised as carriers that may be employed to transport drugs, cytokines and other small molecules to target locations in vivo. In addition, this novel scaffold is a useful material for treating ONFH. An overview of the novel scaffold mimicking the extracellular environment in bone repair. a and b: A gelatine scaffold was cross-linked and freeze-dried within 3D-printed porous titanium. c: Platelets were coated onto the gelatine microscaffold after freeze-drying platelet-rich plasma. d: The microscaffold supported the migration of cells into the titanium pores and their subsequent growth, while the platelets slowly released cell factors, exerting bioactivity.

  6. Evaluation of apoptogenic adenovirus type 5 oncolytic vectors in a Syrian hamster head and neck cancer model

    PubMed Central

    Subramanian, T.; Strebeck, Frank F.; West, Cheri L.; Varvares, Mark; Chinnadurai, G.

    2015-01-01

    Human adenovirus (HAdV) vectors are intensely investigated for virotherapy of a wide variety of human cancers. Here, we have evaluated the effect of two apoptogenic HAdV5 vectors in an immunocompetent Syrian hamster animal model of head and neck cancer. We established two cell lines of hamster cheek pouch squamous cell carcinomas, induced by treatment with 9, 10-dimethyl-1, 2-benzanthracene (DMBA). These cell lines, when infected with HAdV5 mutants lp11w and lp11w/Δ55K (which are defective in the expression of either E1B-19K alone or both E1B-19K and E1B-55K proteins) exhibited enhanced apoptotic and cytotoxic responses. The cheek pouch tumor cells transplanted either subcutaneously at the flanks or in the cheek pouches of hamsters readily formed tumors. Intra-tumoral administration of HAdV5 E1B mutants efficiently suppressed the growth of tumors at both sites. Histological examination of orthotopic tumors revealed reduced vascularity and the expression of the viral fiber antigen in virus-administered cheek pouch tumors. These tumors also exhibited increased caspase-3 levels, suggesting virus-induced apoptosis may contribute to tumor growth suppression. Our results suggest that the apoptogenic HAdV5 vectors may have utility for the treatment of human head and neck cancers. PMID:24874842

  7. Antiresorptive agent-related osteonecrosis of the jaw: Position Paper 2017 of the Japanese Allied Committee on Osteonecrosis of the Jaw.

    PubMed

    Yoneda, Toshiyuki; Hagino, Hiroshi; Sugimoto, Toshitsugu; Ohta, Hiroaki; Takahashi, Shunji; Soen, Satoshi; Taguchi, Akira; Nagata, Toshihiko; Urade, Masahiro; Shibahara, Takahiko; Toyosawa, Satoru

    2017-01-01

    Antiresorptive agent-related osteonecrosis of the jaw (ARONJ) is an intractable, though rare, complication in cancer patients with bone metastases and patients with osteoporosis who are treated with antiresorptive agents, including bisphosphonates and denosumab. Despite the more than 10 years that have passed since the first cases of bisphosphonate-related osteonecrosis of the jaw (BRONJ) were reported, our understanding of the epidemiology and pathophysiology of ARONJ remains limited, and data supported by evidence-based medicine are still sparse. However, the diagnosis and staging of ARONJ, identification of risk factors, and development of preventive and therapeutic approaches have advanced significantly over the past decade. The Position Paper 2017 is an updated version of the Position Paper 2010 of the Japanese Allied Committee on Osteonecrosis of the Jaw, which now comprises six Japanese academic societies. The Position Paper 2017 describes a new diagnostic definition for ARONJ, as proposed by the American Association of Oral and Maxillofacial Surgeons (AAOMS), summarizes our current understanding of the pathophysiology of ARONJ based on a literature search, and suggests methods for physicians and dentists/oral surgeons to manage the disease. In addition, the appropriateness of discontinuing antiresorptive medications (drug holiday) before, during, and after invasive dental treatments is discussed extensively. More importantly, the manuscript also proposes, for the first time, the importance of interactive communication and cooperation between physicians and dentists/oral surgeons for the successful treatment of ARONJ. The Position Paper 2017 is intended to serve as a guide for improving the management of ARONJ patients in Japan.

  8. Glucocorticoid suppression of osteocyte perilacunar remodeling is associated with subchondral bone degeneration in osteonecrosis

    PubMed Central

    Fowler, Tristan W.; Acevedo, Claire; Mazur, Courtney M.; Hall-Glenn, Faith; Fields, Aaron J.; Bale, Hrishikesh A.; Ritchie, Robert O.; Lotz, Jeffrey C.; Vail, Thomas P.; Alliston, Tamara

    2017-01-01

    Through a process called perilacunar remodeling, bone-embedded osteocytes dynamically resorb and replace the surrounding perilacunar bone matrix to maintain mineral homeostasis. The vital canalicular networks required for osteocyte nourishment and communication, as well as the exquisitely organized bone extracellular matrix, also depend upon perilacunar remodeling. Nonetheless, many questions remain about the regulation of perilacunar remodeling and its role in skeletal disease. Here, we find that suppression of osteocyte-driven perilacunar remodeling, a fundamental cellular mechanism, plays a critical role in the glucocorticoid-induced osteonecrosis. In glucocorticoid-treated mice, we find that glucocorticoids coordinately suppress expression of several proteases required for perilacunar remodeling while causing degeneration of the osteocyte lacunocanalicular network, collagen disorganization, and matrix hypermineralization; all of which are apparent in human osteonecrotic lesions. Thus, osteocyte-mediated perilacunar remodeling maintains bone homeostasis, is dysregulated in skeletal disease, and may represent an attractive therapeutic target for the treatment of osteonecrosis. PMID:28327602

  9. Biphosphonates-related osteonecrosis of the jaw: Clinical and physiopathological considerations

    PubMed Central

    Borgioli, Alberto; Viviani, Christian; Duvina, Marco; Brancato, Leila; Spinelli, Giuseppe; Brandi, Maria Luisa; Tonelli, Paolo

    2009-01-01

    Since osteonecrosis of the jaw was related to biphosphonate administration by Marx, studies showing clinical symptoms, drug and surgical therapies overwhelmed the literature. Furthermore, the literature demonstrated the correlation between chronic biphosphonate adsumption and osteonecrosis of the jaw onset. Nitrogen-containing biphosphonates are widely used for the management of metastatic cancer, for prevention and treatment of osteoporosis, for the treatment of Paget's disease, and for the management of acute hypercalcemia. According to our experience, the treatment of BRON-J's lesions is difficult and prolonged. For this reason, in order to avoid these complications it is mandatory to perform a risk staging in patients who must undergo biphosphonate administration. When pharmacologic treatments with antibiotics and local antiseptics are not able to control the development of BRON-J's complications, the clinicians should perform radical surgical treatments such as the resection of the bone involved. PMID:19436626

  10. Oral Bisphosphonate Related Osteonecrosis of the Jaw: A Challenging Adverse Effect

    PubMed Central

    2013-01-01

    Oral bisphosphonates are the most commonly prescribed antiresorptive drugs for the treatment of osteoporosis. However, there are several adverse effects associated with oral bisphosphonates including the bisphosphonate related osteonecrosis of the jaw (BRONJ). With a better understanding of this side effect, reported incidences for BRONJ in oral bisphosphonate users have increased in time. The pathogenesis of BRONJ has not been well determined. Several risk factors such as dentoalveolar surgery, therapy duration, and concomitant steroid usage have been linked to BRONJ. Conservative and surgical methods can be preferred in the treatment. Preventative measures are of great importance for the patients at high risk. In this paper, osteonecrosis of the jaw secondary to oral bisphosphonates was reviewed in order to increase awareness as well as to renew the current knowledge. PMID:23762600

  11. Nitrogen containing bisphosphonates associated osteonecrosis of the jaws: A review for past 10 year literature

    PubMed Central

    Kumar, Vijay; Shahi, Ashish Kumar

    2014-01-01

    Nitrogen containing bisphosphonate (N-BP) therapy is used extensively to treat osteoporosis and osteolytic bone lesions. Recently, a special form of osteonecrosis limited to the maxillofacial skeleton has been discovered especially within those patients who are receiving either long-term N-BP therapy alone and/or associated with invasive dental procedure. Bisphosphonates accumulate almost exclusively in maxillofacial skeleton owing to high bone turn over remodeling to maintain the mechanical competence. The pathogenesis and why it commonly appears in maxillofacial skeleton and the fixed treatment strategies remains unknown. The aim of this study was to improve the clinician understanding of N-BPs associated osteonecrosis of maxillofacial skeleton by reviewing the past 10 year literature. PMID:24932183

  12. A Fully Nonlinear, Dynamically Consistent Numerical Model for Solid-Body Ship Motion. I. Ship Motion with Fixed Heading

    NASA Technical Reports Server (NTRS)

    Lin, Ray-Quing; Kuang, Weijia

    2011-01-01

    In this paper, we describe the details of our numerical model for simulating ship solidbody motion in a given environment. In this model, the fully nonlinear dynamical equations governing the time-varying solid-body ship motion under the forces arising from ship wave interactions are solved with given initial conditions. The net force and moment (torque) on the ship body are directly calculated via integration of the hydrodynamic pressure over the wetted surface and the buoyancy effect from the underwater volume of the actual ship hull with a hybrid finite-difference/finite-element method. Neither empirical nor free parametrization is introduced in this model, i.e. no a priori experimental data are needed for modelling. This model is benchmarked with many experiments of various ship hulls for heave, roll and pitch motion. In addition to the benchmark cases, numerical experiments are also carried out for strongly nonlinear ship motion with a fixed heading. These new cases demonstrate clearly the importance of nonlinearities in ship motion modelling.

  13. The effect of numbered heads together (NHT) cooperative learning model on the cognitive achievement of students with different academic ability

    NASA Astrophysics Data System (ADS)

    Leasa, Marleny; Duran Corebima, Aloysius

    2017-01-01

    Learning models and academic ability may affect students’ achievement in science. This study, thus aimed to investigate the effect of numbered heads together (NHT) cooperative learning model on elementary students’ cognitive achievement in natural science. This study employed a quasi-experimental design with pretest-posttest non-equivalent control group with 2 x 2 factorial. There were two learning models compared NHT and the conventional, and two academic ability high and low. The results of ana Cova test confirmed the difference in the students’ cognitive achievement based on learning models and general academic ability. However, the interaction between learning models and academic ability did not affect the students’ cognitive achievement. In conclusion, teachers are strongly recommended to be more creative in designing learning using other types of cooperative learning models. Also, schools are required to create a better learning environment which is more cooperative to avoid unfair competition among students in the classroom and as a result improve the students’ academic ability. Further research needs to be conducted to explore the contribution of other aspects in cooperative learning toward cognitive achievement of students with different academic ability.

  14. Regional electric field induced by electroconvulsive therapy in a realistic finite element head model: Influence of white matter anisotropic conductivity

    PubMed Central

    Lee, Won Hee; Deng, Zhi-De; Kim, Tae-Seong; Laine, Andrew F.; Lisanby, Sarah H.; Peterchev, Angel V.

    2012-01-01

    We present the first computational study investigating the electric field (E-field) strength generated by various electroconvulsive therapy (ECT) electrode configurations in specific brain regions of interest (ROIs) that have putative roles in the therapeutic action and/or adverse side effects of ECT. This study also characterizes the impact of the white matter (WM) conductivity anisotropy on the E-field distribution. A finite element head model incorporating tissue heterogeneity and WM anisotropic conductivity was constructed based on structural magnetic resonance imaging (MRI) and diffusion tensor MRI data. We computed the spatial E-field distributions generated by three standard ECT electrode placements including bilateral (BL), bifrontal (BF), and right unilateral (RUL) and an investigational electrode configuration for focal electrically administered seizure therapy (FEAST). The key results are that (1) the median E-field strength over the whole brain is 3.9, 1.5, 2.3, and 2.6 V/cm for the BL, BF, RUL, and FEAST electrode configurations, respectively, which coupled with the broad spread of the BL E-field suggests a biophysical basis for observations of superior efficacy of BL ECT compared to BF and RUL ECT; (2) in the hippocampi, BL ECT produces a median E-field of 4.8 V/cm that is 1.5–2.8 times stronger than that for the other electrode configurations, consistent with the more pronounced amnestic effects of BL ECT; and (3) neglecting the WM conductivity anisotropy results in E-field strength error up to 18% overall and up to 39% in specific ROIs, motivating the inclusion of the WM conductivity anisotropy in accurate head models. This computational study demonstrates how the realistic finite element head model incorporating tissue conductivity anisotropy provides quantitative insight into the biophysics of ECT, which may shed light on the differential clinical outcomes seen with various forms of ECT, and may guide the development of novel stimulation

  15. Electromagnetic Head-And-Neck Hyperthermia Applicator: Experimental Phantom Verification and FDTD Model

    SciTech Connect

    Paulides, Margarethus M. . E-mail: M.Paulides@ErasmusMC.nl; Bakker, Jurriaan F.; Rhoon, Gerard C. van

    2007-06-01

    Purpose: To experimentally verify the feasibility of focused heating in the neck region by an array of two rings of six electromagnetic antennas. We also measured the dynamic specific absorption rate (SAR) steering possibilities of this setup and compared these SAR patterns to simulations. Methods and Materials: Using a specially constructed laboratory prototype head-and-neck applicator, including a neck-mimicking cylindrical muscle phantom, we performed SAR measurements by electric field, Schottky-diode sheet measurements and, using the power-pulse technique, by fiberoptic thermometry and infrared thermography. Using phase steering, we also steered the SAR distribution in radial and axial directions. All measured distributions were compared with the predictions by a finite-difference time-domain-based electromagnetic simulator. Results: A central 50% iso-SAR focus of 35 {+-} 3 mm in diameter and about 100 {+-} 15 mm in length was obtained for all investigated settings. Furthermore, this SAR focus could be steered toward the desired location in the radial and axial directions with an accuracy of {approx}5 mm. The SAR distributions as measured by all three experimental methods were well predicted by the simulations. Conclusion: The results of our study have shown that focused heating in the neck is feasible and that this focus can be effectively steered in the radial and axial directions. For quality assurance measurements, we believe that the Schottky-diode sheet provides the best compromise among effort, speed, and accuracy, although a more specific and improved design is warranted.

  16. Systemic Administration of Induced Neural Stem Cells Regulates Complement Activation in Mouse Closed Head Injury Models

    PubMed Central

    Gao, Mou; Dong, Qin; Yao, Hui; Lu, Yingzhou; Ji, Xinchao; Zou, Mingming; Yang, Zhijun; Xu, Minhui; Xu, Ruxiang

    2017-01-01

    Complement activation plays important roles in the pathogenesis of central nervous system (CNS) diseases. Patients face neurological disorders due to the development of complement activation, which contributes to cell apoptosis, brain edema, blood-brain barrier dysfunction and inflammatory infiltration. We previously reported that induced neural stem cells (iNSCs) can promote neurological functional recovery in closed head injury (CHI) animals. Remarkably, we discovered that local iNSC grafts have the potential to modulate CNS inflammation post-CHI. In this study, we aimed to explore the role of systemically delivered iNSCs in complement activation following CNS injury. Our data showed that iNSC grafts decreased the levels of sera C3a and C5a and down-regulated the expression of C3d, C9, active Caspase-3 and Bax in the brain, kidney and lung tissues of CHI mice. Furthermore, iNSC grafts decreased the levels of C3d+/NeuN+, C5b-9+/NeuN+, C3d+/Map2+ and C5b-9+/Map2+ neurons in the injured cortices of CHI mice. Subsequently, we explored the mechanisms underlying these effects. With flow cytometry analysis, we observed a dramatic increase in complement receptor type 1-related protein y (Crry) expression in iNSCs after CHI mouse serum treatment. Moreover, both in vitro and in vivo loss-of-function studies revealed that iNSCs could modulate complement activation via Crry expression. PMID:28383046

  17. Medical treatment of osteonecrosis of the knee associated with thrombophilia-hypofibrinolysis.

    PubMed

    Glueck, Charles J; Freiberg, Richard A; Wang, Ping

    2014-10-01

    In 6 patients with stage II knee osteonecrosis, all 6 with thrombophilia and 4 with concurrent hypofibrinolysis, the authors prospectively determined whether anticoagulation with enoxaparin could prevent collapse and progression to osteoarthritis, ameliorate pain, and restore function. The 6 patients were treated with enoxaparin (40 to 60 mg/d for 3 or more months) as mandated by a US Food and Drug Administration-approved protocol. In post-enoxaparin prospective follow-up, patients were reassessed clinically every 4 to 6 months, and radiographs were obtained every year. The 6 patients followed up at 15.1, 7.5, 3.9, 2.25, 2, and 1 year, respectively. None progressed to joint collapse or severe osteoarthritis. Four became and remained asymptomatic at 2-, 3.9-, 7.5-, and 15.1-year follow-up, respectively. A fifth patient did not progress to collapse or severe osteoarthritis but had residual pain at 2.25-year follow-up. The sixth patient had no symptomatic benefit on enoxaparin but improved on rivaroxaban at 1-year follow-up. Two patients had recurrences of knee pain 1 and 4 years after their initial treatment with enoxaparin. One resolved after a second course of enoxaparin, and the other, with a second recurrence 1 year after the second course, resolved after a third course. Pretreatment, all 6 patients required canes, crutches, or wheelchairs, but after enoxaparin, no patient required them, and walking was unrestricted. Thrombophilia-hypofibrinolysis contributes to the pathogenesis of knee osteonecrosis. Thrombophilic-hypofibrinolytic patients with stage II knee osteonecrosis treated with enoxaparin have had no collapse or progression to severe osteoarthritis, and most have had resolution of pain and restoration of full function. This represents a major improvement compared with the natural history of untreated spontaneous knee osteonecrosis.

  18. Incorporating single-side sparing in models for predicting parotid dose sparing in head and neck IMRT

    SciTech Connect

    Yuan, Lulin Wu, Q. Jackie; Yin, Fang-Fang; Yoo, David; Jiang, Yuliang; Ge, Yaorong

    2014-02-15

    Purpose: Sparing of single-side parotid gland is a common practice in head-and-neck (HN) intensity modulated radiation therapy (IMRT) planning. It is a special case of dose sparing tradeoff between different organs-at-risk. The authors describe an improved mathematical model for predicting achievable dose sparing in parotid glands in HN IMRT planning that incorporates single-side sparing considerations based on patient anatomy and learning from prior plan data. Methods: Among 68 HN cases analyzed retrospectively, 35 cases had physician prescribed single-side parotid sparing preferences. The single-side sparing model was trained with cases which had single-side sparing preferences, while the standard model was trained with the remainder of cases. A receiver operating characteristics (ROC) analysis was performed to determine the best criterion that separates the two case groups using the physician's single-side sparing prescription as ground truth. The final predictive model (combined model) takes into account the single-side sparing by switching between the standard and single-side sparing models according to the single-side sparing criterion. The models were tested with 20 additional cases. The significance of the improvement of prediction accuracy by the combined model over the standard model was evaluated using the Wilcoxon rank-sum test. Results: Using the ROC analysis, the best single-side sparing criterion is (1) the predicted median dose of one parotid is higher than 24 Gy; and (2) that of the other is higher than 7 Gy. This criterion gives a true positive rate of 0.82 and a false positive rate of 0.19, respectively. For the bilateral sparing cases, the combined and the standard models performed equally well, with the median of the prediction errors for parotid median dose being 0.34 Gy by both models (p = 0.81). For the single-side sparing cases, the standard model overestimates the median dose by 7.8 Gy on average, while the predictions by the combined

  19. A New Model for Predicting Acute Mucosal Toxicity in Head-and-Neck Cancer Patients Undergoing Radiotherapy With Altered Schedules

    SciTech Connect

    Strigari, Lidia; Pedicini, Piernicola; D'Andrea, Marco; Pinnaro, Paola; Marucci, Laura; Giordano, Carolina; Benassi, Marcello

    2012-08-01

    Purpose: One of the worst radiation-induced acute effects in treating head-and-neck (HN) cancer is grade 3 or higher acute (oral and pharyngeal) mucosal toxicity (AMT), caused by the killing/depletion of mucosa cells. Here we aim to testing a predictive model of the AMT in HN cancer patients receiving different radiotherapy schedules. Methods and Materials: Various radiotherapeutic schedules have been reviewed and classified as tolerable or intolerable based on AMT severity. A modified normal tissue complication probability (NTCP) model has been investigated to describe AMT data in radiotherapy regimens, both conventional and altered in dose and overall treatment time (OTT). We tested the hypothesis that such a model could also be applied to identify intolerable treatment and to predict AMT. This AMT NTCP model has been compared with other published predictive models to identify schedules that are either tolerable or intolerable. The area under the curve (AUC) was calculated for all models, assuming treatment tolerance as the gold standard. The correlation between AMT and the predicted toxicity rate was assessed by a Pearson correlation test. Results: The AMT NTCP model was able to distinguish between acceptable and intolerable schedules among the data available for the study (AUC = 0.84, 95% confidence interval = 0.75-0.92). In the equivalent dose at 2 Gy/fraction (EQD2) vs OTT space, the proposed model shows a trend similar to that of models proposed by other authors, but was superior in detecting some intolerable schedules. Moreover, it was able to predict the incidence of {>=}G3 AMT. Conclusion: The proposed model is able to predict {>=}G3 AMT after HN cancer radiotherapy, and could be useful for designing altered/hypofractionated schedules to reduce the incidence of AMT.

  20. Alendronate-associated osteonecrosis of the jaws: a review of the main topics.

    PubMed

    Paiva-Fonseca, F; Santos-Silva, A-R; Della-Coletta, R; Vargas, P-A; Lopes, M-A

    2014-03-01

    Bisphosphonates is a group of inorganic pyrophosphates analogues that suppress bone resorption by inducing osteoclast inactivation, being frequently used for management of diseases affecting bone metabolism, bone metastases and bone tumors. However, since 2003 many cases describing the presence of necrotic bone exposures in the jaws have been described in patients receiving these drugs, what represent a significant complication of bisphosphonates treatment. The overall incidence of bisphosphonate-related osteonecrosis of the jaws is low, ranging from 0.7% to 12%, mainly observed in those patients receiving intravenously treatment. Osteonecrosis of the jaws associated to oral bisphosphonate, particularly alendronate, has also been reported by a number of authors. Considering that alendronate is one of the most used drug worldwide, specially for treatment of osteoporosis, a better understanding of osteonecrosis of the jaws related to its use and how to manage these patients is extremely important. Therefore, in the current manuscript the authors aim to review the most important topics related to this pathological presentation.

  1. Diseases having an influence on inhibition of angiogenesis as risk factors of osteonecrosis of the jaw

    PubMed Central

    2016-01-01

    Objectives The objective of this study was to retrospectively investigate the association of diseases having an influence on inhibition of angiogenesis such as hypertension, diabetes mellitus type II, hypercholesterolemia, and rheumatoid arthritis (RA) with the development of osteonecrosis of the jaws. Materials and Methods The 135 patients were allocated into 4 groups of bisphosphonate-related osteonecrosis of the jaw (BRONJ) group (1A); non-BRONJ group (1B); osteonecrosis of the jaw (ONJ) group (2A); and control group (2B), according to histologic results and use of bisphosphonate. This retrospective study was conducted with patients who were treated in one institute from 2012 to 2013. Fisher's exact test and logistic regression analysis were used to analyze the odds ratios of diseases having an influence on inhibition of angiogenesis for development of ONJ. Results The effects of diabetes and hypertension were not statistically significant on development of ONJ. When not considering bisphosphonate use, RA exhibited a high odds ratio of 3.23 (P=0.094), while hyperlipidemia showed an odds ratio of 2.10 (P=0.144) for development of ONJ. More than one disease that had an influence on inhibition of angiogenesis showed a statistically significant odds ratio of 2.54 (P=0.012) for development of ONJ. Conclusion Patients without diseases having an influence on inhibition of angiogenesis were at less risk for developing ONJ. PMID:27847735

  2. Jaw osteonecrosis management around a dental implant inserted 2 years before starting treatment with zoledronic acid

    PubMed Central

    Marín-Fernández, Ana-Belén; García Medina, Blas; Aguilar-Salvatierra, Antonio; Jiménez-Burkhardt, Alberto

    2015-01-01

    Bisphosphonates (BP) are a type of drug known to inhibit bone resorption through complex interventions. Their primary mechanism of action is aimed at the cellular level, inhibiting osteoclast activity and so bone resorption. BPs are widely used, with many patients receiving continuous treatment for years. But it is well known that these drugs can produce osteonecrosis of the jaw (ONJ). Zoledronic acid (ZA) is an intravenous BP used in the treatment and prophylaxis of bone disease in patients with malignant tumors with bone implication. ZA is the most potent BP in clinical development. This report describes the case of a 62-year-old woman with breast cancer antecedents which relapsed, who had received a maxillary dental implant two years before the start of therapy with zoledronic acid. She later developed osteonecrosis of the jaw (ONJ), which began in the peri-implant area, and was treated for stage 3 ONJ by sub-total maxillectomy. Key words:Bisphosphonates, zoledronic acid, osteonecrosis of the jaw, peri-implantitis, maxillectomy. PMID:26330946

  3. Oral bisphosphonate-associated osteonecrosis of maxillary bone: A review of 18 cases

    PubMed Central

    Mardenlli, Fabiana; Paz, Marisa

    2014-01-01

    Biphosphonate-associated maxillary bone osteonecrosis (BPMO) is a complication related to nitrogen-containing biphosphonate therapy. This adverse effect occasionally appears in patients who are administered biphosphonates through intravenous infusion for the treatment of cancer involving bone metastases. It can also present, in a lesser degree, in patients who take these drugs orally for the treatment of osteoporosis. Lately, there has been an increase in the number of cases of osteopenia and osteoporosis due to the increasing life expectancy of the world’s population. In our country, a risk group composed mainly of older women who have been diagnosed with osteopenia or osteoporosis, and submitted to the continuous action of oral biphosphonates, is emerging. In this paper we present 18 cases of BPMO associated to the use of oral biphosphonates, diagnosed and treated in the Department of Stomatology of the School or Dentistry at Universidad Nacional de Rosario, Argentina. A protocol was designed in which the following information was recorded: age and sex of the patients, the original disease which led to therapy with oral biphosphonates, the drugs used and the period in which those drugs were administered, the clinical features and location of the lesions, together with triggering factors. Key words:Maxillary osteonecrosis, mandibular osteonecrosis, oral biphosphonates, alendronate, ibandronate. PMID:25674321

  4. Treatment of osteonecrosis of the jaw related to bisphosphonates and other antiresorptive agents

    PubMed Central

    Oñate-Sánchez, Ricardo-Elías

    2016-01-01

    Background The clinical management of medication-related osteonecrosis of the jaw (MRONJ) in patients treated with bisphosphonates and other antiresorptive agents is subject to controversy. The American Association of Oral and Maxillofacial Surgeons (AAOMS) has developed guidelines for the correct management of the disorder which are revised and updated by a panel of experts. Material and Methods The present systematic review analyzes the different treatments currently used to treat this clinical condition, based on the PRISMA® (Preferred Reporting Items for Systematic Reviews and Meta-Analyses) statement published in 2009. An electronic Medline search was made of the PubMed database, covering the period 2006-2014. The last search date was 31 December 2014. Results A total of 29 articles were selected from the initial search according to the different drugs implicated in the appearance of osteonecrosis; the treatment modality used according to the stage of the disease; and the recorded success rate. Conclusions It is currently still recommended that the management of MRONJ should be decided according to the stage of the disease – conservative treatment being preferred in early stages without symptoms, while surgical management is preferred in the case of bone exposure with symptoms. Key words:Osteonecrosis, medication, bisphosphonates, treatments, review PMID:27475683

  5. Intracerebral hemorrhage (ICH) evaluation with a novel magnetic induction sensor: a preliminary study using the Chinese head model.

    PubMed

    Zhang, Ziyi; Liu, Peiguo; Zhou, Dongming; Zhang, Liang; Lei, Hengdong

    2014-01-01

    Biomedical magnetic induction measurement is a promising method for the detection of intracerebral hemorrhage (ICH), especially in China. Aiming at overcoming the problem of low sensitivity, a magnetic induction sensor is chosen to replace the conventional sensors. It uses a two-arm Archimedean spiral coil as the exciter and a circular coil as the receiver. In order to carry out high-fidelity simula