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991.
Pogoryelov D Klyszejko AL Krasnoselska GO Heller EM Leone V Langer JD Vonck J Müller DJ Faraldo-Gómez JD Meier T 《Proceedings of the National Academy of Sciences of the United States of America》2012,109(25):E1599-E1608
ATP synthase membrane rotors consist of a ring of c-subunits whose stoichiometry is constant for a given species but variable across different ones. We investigated the importance of c/c-subunit contacts by site-directed mutagenesis of a conserved stretch of glycines (GxGxGxGxG) in a bacterial c(11) ring. Structural and biochemical studies show a direct, specific influence on the c-subunit stoichiometry, revealing c(<11), c(12), c(13), c(14), and c(>14) rings. Molecular dynamics simulations rationalize this effect in terms of the energetics and geometry of the c-subunit interfaces. Quantitative data from a spectroscopic interaction study demonstrate that the complex assembly is independent of the c-ring size. Real-time ATP synthesis experiments in proteoliposomes show the mutant enzyme, harboring the larger c(12) instead of c(11), is functional at lower ion motive force. The high degree of compliance in the architecture of the ATP synthase rotor offers a rationale for the natural diversity of c-ring stoichiometries, which likely reflect adaptations to specific bioenergetic demands. These results provide the basis for bioengineering ATP synthases with customized ion-to-ATP ratios, by sequence modifications. 相似文献
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996.
AA Righetti AY Koua LG Adiossan D Glinz RF Hurrell EK N'goran S Niamké R Wegmüller J Utzinger 《The American journal of tropical medicine and hygiene》2012,87(3):425-434
Anemia affects one-quarter of the world''s population, but its etiology remains poorly understood. We determined the prevalence of anemia and studied underlying risk factors in infants (6–23 months), young school-aged children (6–8 years), and young non-pregnant women (15–25 years) in south-central Côte d''Ivoire. Blood, stool, and urine samples were subjected to standardized, quality-controlled methods. We found high prevalence of anemia, malaria, inflammation, and deficiencies of iron, riboflavin, and vitamin A but low prevalence and intensities of soil-transmitted helminth and schistosome infections. Multivariate regression analysis revealed significant associations between anemia and Plasmodium falciparum for infants, inflammation for school-aged children, and cellular iron deficiency for both school-aged children and non-pregnant women. Women with riboflavin deficiency had significantly lower odds of anemia. Our findings call for interventions to protect infants from malaria, improved intake of dietary iron, better access to health care, and health education. 相似文献
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998.
Möller B Terheyden H Açil Y Purcz NM Hertrampf K Tabakov A Behrens E Wiltfang J 《International journal of oral and maxillofacial surgery》2012,41(5):638-645
This study compared the biocompatibility in vitro and the osseointegration in vivo of zirconium and titanium implants regarding implant surfaces and the bone-implant contacts. The different implant surfaces and the biocompatibility of zirconium versus titanium implants were determined by vitality and cytotoxic tests in vitro. The contact of the osteoblasts to the implant surface was determined by scanning electron microscopy (SEM). The in vivo study for osseointegration was performed in domestic pigs over 4 and 12 weeks. In each animal, 4 zirconium and 4 titanium implants (WhiteSky, BlueSky, Bredent, Germany) were inserted in the os frontale and analysed by histomorphometry. Cytotoxicity and SEM showed good biocompatibility in relation to the investigated implant materials. Histological results showed direct bone-implant contact of the implant surfaces. The zirconium implants showed a slight delay in osseointegration in terms of bone-implant contact as measured by histomorphometry (after 4 weeks, zirconium (59.3 ± 4.6%) versus titanium (64.1 ± 3.9%); after 12 weeks, zirconium (67.1 ± 2.3%) versus titanium (73.6 ± 3.2%). A statistically significant difference between the two groups was not observed. The results indicated similar biocompatibility and osseointegration for zirconium compared to titanium implants. 相似文献
999.
Ritter L Reiz SD Rothamel D Dreiseidler T Karapetian V Scheer M Zöller JE 《Clinical oral implants research》2012,23(4):447-452
Objective: Virtual wax‐ups based on three‐dimensional (3D) surface models can be matched (i.e. registered) to cone beam computed tomography (CBCT) data of the same patient for dental implant planning. Thereby, implant planning software can visualize anatomical and prosthetic information simultaneously. The aim of this study is to assess the accuracy of a newly developed registration process. Material and methods: Data pairs of CBCT and 3D surface data of 16 patients for dental implant planning were registered and the discrepancy between the visualized 3D surface data and the corresponding CBCT data were measured on 64 teeth at seven points by two investigators in two iterations with a total of 1792 measurements. Results: All data pairs were matched successfully and mean distances between CBCT and 3D surface data were between 0.03(±0.33) and 0.14(±0.18) mm. At two of seven measuring points, statistically significant correlations were determined between the measured error and the presence and type of restorations. Registration errors in maxilla and mandible were not statistically significantly different. Conclusion: According to the results of this study, registration of 3D surface data and CBCT data works reliably and is sufficiently accurate for dental implant planning. Thereby, barium‐sulfate scanning templates can be avoided and dental implant planning can be accomplished fully virtual. To cite this article: Ritter L, Reiz SD, Rothamel D, Dreiseidler T, Karapetian V, Scheer M, Zöller JE. Registration accuracy of three‐dimensional surface and cone beam computed tomography data for virtual implant planning.Clin. Oral Impl. Res. 23 , 2012 447–452.doi: 10.1111/j.1600‐0501.2011.02159.x 相似文献
1000.
Y. Açil B. Möller P. Niehoff K. Rachko V. Gassling J. Wiltfang M.J.K. Simon 《Journal of cranio-maxillo-facial surgery》2012,40(8):e229-e235
IntroductionOsteonecrosis of the jaw (ONJ) is an emerging condition in patients undergoing long-term administration of bisphosphonates (BP) for the treatment of osteoporosis and hypercalcaemia associated with malignancy, multiple myeloma, and metastatic breast and prostate cancers. This is a follow-up study, its purpose was to examine the effects in-vitro of intravenous zoledronic acid (ZOL) and pamidronate (PAM) and oral alendronate (FOS) on the human oral cavity using gingival fibroblasts and osteoblasts cells and, in addition, osteogenic sarcoma cells (SaOS-2-cells).Materials and methodsHuman gingival fibroblasts, osteoblasts and SaOS-2-cells were seeded on multiple 6-well plates at a density of 5 × 105 cells in a 4-week cell culture. Four different concentrations (1, 5, 10, 20 μM) of each BP (ZOL, PAM, FOS) and pyrophosphate were used in this study.ResultsAll BP decreased collagen production and lowered cell proliferation in-vitro. ZOL was the component with most inhibitory effect.ConclusionThe findings in this study suggest that ZOL, PAM and FOS generally diminish cell proliferation and collagen production of human gingival fibroblasts, osteoblasts and SaOS-2-cells. The present follow-up study shows that not only ZOL and PAM but also FOS have a strong inhibitory effect on collagen production and cell survival in-vitro. 相似文献