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Distal Site (distal + site)
Selected AbstractsMaterial properties are related to stress fracture callus and porosity of cortical bone tissue at affected and unaffected sitesJOURNAL OF ORTHOPAEDIC RESEARCH, Issue 10 2009Rachel C. Entwistle Abstract Stress fractures are overuse injuries of bone that affect elite athletes and military recruits. One response of cortical bone to stress fracture is to lay down periosteal callus. The objectives of this study were to determine if material properties are different among bones with different stages of stress fracture callus, at both a callus site and at a distal site. Cortical specimens were mechanically tested to determine their stress,strain response. Material property differences were examined using nonparametric and regression analyses. At the callus site, material properties were low during the earliest stages of callus, higher with increasing callus maturity, but dropped at the late stage of callus. At the distal site, the material properties were low during early stages of callus and approached, or returned to, those of bones without callus during the late stages of callus. The effects of stress fracture and bone callus are not limited to the focal site of stress fracture. © 2009 Orthopaedic Research Society. Published by Wiley Periodicals, Inc. J Orthop Res 27:1272,1279, 2009 [source] Nitric Oxide and the Paranasal SinusesTHE ANATOMICAL RECORD : ADVANCES IN INTEGRATIVE ANATOMY AND EVOLUTIONARY BIOLOGY, Issue 11 2008Jon O. Lundberg Abstract The discovery within the paranasal sinuses for the production of nitric oxide (NO) has altered the traditional explanations of sinus physiology. This review article reports the ongoing investigation of sinus physiology beginning with the discovery of NO gas production in the paranasal sinuses that occurred in 1995, and the impact that finding has had both in the basic science and clinical arenas. It was shown that healthy paranasal sinus epithelium expresses an inducible NO synthase that continuously generates large amounts of NO, a pluripotent gaseous messenger with potent vasodilating, and antimicrobial activity. This NO can be measured noninvasively in nasally exhaled breath. The role of NO in the sinuses is likely to enhance local host defense mechanisms via direct inhibition of pathogen growth and stimulation of mucociliary activity. The NO concentration in a healthy sinus exceeds those that are needed for antibacterial effects in vitro. In patients with primary ciliary dyskinesia (PCD) and in cystic fibrosis, nasal NO is extremely low. This defect NO generation likely contributes to the great susceptibility to chronic sinusitis in these patients. In addition, the low-nasal NO is of diagnostic value especially in PCD, where nasal NO is very low or absent. Intriguingly, NO gas from the nose and sinuses is inhaled with every breath and reaches the lungs in a more diluted form to enhance pulmonary oxygen uptake via local vasodilation. In this sense NO may be regarded as an "aerocrine" hormone that is produced in the nose and sinuses and transported to a distal site of action with every inhalation. Anat Rec, 291:1479,1484, 2008. © 2008 Wiley-Liss, Inc. [source] Expression, crystallization and preliminary crystallographic analysis of RNA-binding protein Hfq (YmaH) from Bacillus subtilis in complex with an RNA aptamerACTA CRYSTALLOGRAPHICA SECTION F (ELECTRONIC), Issue 5 2010Seiki Baba The Hfq protein is a hexameric RNA-binding protein which regulates gene expression by binding to RNA under the influence of diverse environmental stresses. Its ring structure binds various types of RNA, including mRNA and sRNA. RNA-bound structures of Hfq from Escherichia coli and Staphylococcus aureus have been revealed to have poly(A) RNA at the distal site and U-rich RNA at the proximal site, respectively. Here, crystals of a complex of the Bacillus subtilis Hfq protein with an A/G-repeat 7-mer RNA (Hfq,RNA) that were prepared using the hanging-drop vapour-diffusion technique are reported. The type 1 Hfq,RNA crystals belonged to space group I422, with unit-cell parameters a = b = 123.70, c = 119.13,Å, while the type 2 Hfq,RNA crystals belonged to space group F222, with unit-cell parameters a = 91.92, b = 92.50, c = 114.92,Å. Diffraction data were collected to a resolution of 2.20,Å from both crystal forms. The hexameric structure of the Hfq protein was clearly shown by self-rotation analysis. [source] Two-step counterdiffusion protocol for the crystallization of haemoglobin II from Lucina pectinata in the pH range 4,9ACTA CRYSTALLOGRAPHICA SECTION F (ELECTRONIC), Issue 3 2010Carlos A. Nieves-Marrero Lucina pectinata haemoglobin II (HbII) transports oxygen in the presence of H2S to the symbiotic system in this bivalve mollusc. The composition of the haem pocket at the distal site includes TyrB10 and GlnE7, which are very common in other haem proteins. Obtaining crystals of oxyHbII at various pH values is required in order to elucidate the changes in the conformations of TyrB10 and GlnE7 and structural scenarios induced by changes in pH. Here, the growth of crystals of oxyHbII using the capillary counterdiffusion (CCD) technique at various pH values using a two-step protocol is reported. In the first step, a mini-screen was used to validate sodium formate as the best precipitating reagent for the growth of oxyHbII crystals. The second step, a pH screen typically used for optimization, was used to produce crystals in the pH range 4,9. Very well faceted prismatic ruby-red crystals were obtained at all pH values. X-ray data sets were acquired using synchrotron radiation of wavelength 0.886,Å (for the crystals obtained at pH 5) and 0.908,Å (for those obtained at pH 4, 8 and 9) to maximum resolutions of 3.30, 1.95, 1.85 and 2.00,Å for the crystals obtained at pH 4, 5, 8 and 9, respectively. All of the crystals were isomorphous and belonged to space group P42212. [source] Truncated hemoglobins: trimming the classical ,three-over-three' globin fold to a minimal sizeBIOCHEMISTRY AND MOLECULAR BIOLOGY EDUCATION, Issue 3 2001Mario Milani Abstract Truncated hemoglobins (trHbs) host the heme in a ,two-over-two' ,-helical sandwich which results from extensive editing of the classical ,three-over-three' globin fold. The three-dimensional structure of trHbs is based on four main ,-helices, arranged in a sort of ,-helical bundle composed of two antiparallel helix pairs (B/E and G/H). Most notably, trHbs deviate from the conventional globin fold in that they display an extended loop substituting for the heme proximal F-helix observed in globins. Moreover, since efficient adaptation of a 110,130 amino acid trHb chain to host the porphyrin ring firstly requires specific chain flexibility, trHbs contain three invariant Gly-based motifs. Inspection of the trHb three-dimensional trHb structures shows that an apparent protein cavity or tunnel would connect the protein surface to an inner region very close to the heme distal site. Such a structural feature, never observed before in (non) vertebrate globins, may have substantial implications for ligand diffusion and binding properties in trHbs. © 2001 IUBMB. Published by Elsevier Science Ltd. All rights reserved. [source] Intestinal regeneration by a novel surgical procedureBRITISH JOURNAL OF SURGERY (NOW INCLUDES EUROPEAN JOURNAL OF SURGERY), Issue 5 2008S.-C. Jwo Background: Treatment of short bowel syndrome is problematical. Small bowel tissue engineering has achieved modest results in animal studies. The aim of this study was to investigate intestinal regeneration in a novel surgical model. Methods: Roux-en-Y bypass procedures were performed on 40 Wistar rats weighing 250,350 g. Animals were killed at 1, 2, 3, 4, 8, 12 and 24 weeks after implantation with a 3-cm silicone tube. The spatio temporal relationship of intestinal regeneration was analysed using three-dimensional multislice computed tomography, and examination of sequential morphological changes on gross or histological findings and measurement of missing intestinal tissue (growth defects). Results: Progressive intestinal regeneration on a silicone tube was identifiable in 35 animals. Most adhesions were initially localized on the tube but spread to a distal site 4 weeks after implantation. Growth defects decreased with time, with a marked reduction in the first 4 weeks and a gradual reduction to week 24 after implantation. Luminal patency shown radiologically as well as sequential histological findings, such as mucosal lining, matrix remodelling and muscular regeneration, suggested that regeneration of intestinal tissue took place, not merely scar contraction. Conclusion: Non-invasive as well as histomorphological assessment followed intestinal regeneration over time in this model, which provides scope for further studies. Copyright © 2008 British Journal of Surgery Society Ltd. Published by John Wiley & Sons, Ltd. [source] Validation of a dental image analyzer tool to measure alveolar bone loss in periodontitis patientsJOURNAL OF PERIODONTAL RESEARCH, Issue 1 2009W. J. Teeuw Background and Objective:, Radiographs are an essential adjunct to the clinical examination for periodontal diagnoses. Over the past few years, digital radiographs have become available for use in clinical practice. Therefore, the present study investigated whether measuring alveolar bone loss, using digital radiographs with a newly constructed dental image analyzer tool was comparable to the conventional method, using intra-oral radiographs on film, a light box and a Schei ruler. Material and Methods:, Alveolar bone loss of the mesial and distal sites of 60 randomly selected teeth from 12 patients with periodontitis was measured using the conventional method, and then using the dental image analyzer tool, by five dentists. The conventional method scored bone loss in categories of 10% increments relative to the total root length, whereas the software dental image analyzer tool calculated bone loss in 0.1% increments relative to the total root length after crucial landmarks were identified. Results:, Both methods showed a high interobserver reliability for bone loss measurements in nonmolar and molar sites (intraclass correlation coefficient , 0.88). Also, a high reliability between both methods was demonstrated (intraclass correlation coefficient nonmolar sites, 0.98; intraclass correlation coefficient molar sites, 0.95). In addition, the new dental image analyzer tool showed a high sensitivity (1.00) and a high specificity (0.91) in selecting teeth with , 50% or < 50% alveolar bone loss in comparison with the conventional method. Conclusion:, This study provides evidence that, if digital radiographs are available, the dental image analyzer tool can reliably replace the conventional method for measuring alveolar bone loss in periodontitis patients. [source] The infrabony defect and its determinantsJOURNAL OF PERIODONTAL RESEARCH, Issue 6 2006C. -K. Background and Objective:, The purpose of this study was to assess the defect width of infrabony defects in a cross-sectional study and to evaluate whether the defect width is a function of defect depth. Material and Methods:, Complete sets of intra-oral radiographs of patients with severe periodontitis, which exhibited at least one infrabony defect, were digitised and evaluated. The following parameters were measured: depth and width of the infrabony defect, defect angle, and width of the interdental spaces. Results:, Fifty-one patients (26 women), ranging from 21 to 73 yr of age (48.5 ± 13.4 yr), contributed a total of 1272 teeth with 135 infrabony defects (10.6%). Seventeen infrabony defects were located at sites without a neighboring tooth. Infrabony defects were statistically more prevalent in the mandible (n = 82) than in the maxilla (p = 0.013), and more prevalent at mesial sites (n = 92) than at distal sites (p < 0.001). At infrabony defects, the width of interdental spaces at the most coronal extension of the alveolar crest could be measured only at sites with neigboring teeth 2.67 ± 0.78 mm (range: 1.19,5.70 mm). Analysis failed to reveal a statistically significant difference between defect width at sites with (2.64 ± 0.82 mm) and sites without (2.76 ± 0.70 mm) a neighboring tooth. Multilevel regression analysis revealed narrow defect angles to be related to deep infrabony defects, whereas width of the interdental space and distal location were related to wide defects. Conclusion:, Defect angle depended on defect depth and defect width was not different at sites with or without a neighboring tooth. Even in severe periodontitis, infrabony defects are found only at a minority of teeth. [source] Actions of melatonin mixed with collagenized porcine bone versus porcine bone only on osteointegration of dental implantsJOURNAL OF PINEAL RESEARCH, Issue 3 2010José Luis Calvo-Guirado Abstract:, This study evaluated the effect of the topical application of melatonin mixed with collagenized porcine bone on the osteointegration on the rough discrete calcium deposit (DCD) surface implants in Beagle dogs 3 months after their insertion. In preparation for subsequent insertion of dental implants, lower molars were extracted from 12 Beagle dogs. Each mandible received two parallel wall expanded platform implants with a DCD surface of 4 mm in diameter and 10 mm in length. The implants were randomly assigned to the distal sites on each mandible in the molar area and the gaps were filled with 5 mg lyophilized powdered melatonin and porcine bone and collagenized porcine bone alone. Ten histological sections per implant were obtained for histomorphometric studies. After a 4-wk treatment period, melatonin plus porcine bone significantly increased the perimeter of bone that was in direct contact with the treated implants (P < 0.0001), bone density (P < 0.0001), and new bone formation (P < 0.0001) in comparison with porcine bone alone around the implants. Melatonin plus collagenized porcine bone on DCD surface may act as a biomimetic agent in the placement of endo-osseous dental implants and enhance the osteointegration. Melatonin combined with porcine bone on DCD implants reveals more bone in implant contact at 12 wk (84.5 ± 1.5%) compared with porcine bone alone treated area (67.17 ± 1.2%). [source] | |||||||||||||