1,413 research outputs found
Histopathologic parameters as predictors of response to endoscopic sinus surgery in nonallergic patients with chronic rhinosinusitis
OBJECTIVE: To estimate the predictable value of histopathologic parameters in chronic rhinosinusitis (CRS) for response to endoscopic sinus surgery (ESS). - - - - - STUDY DESIGN: Symptomatology was rated in 100 patients prior to as well as 12 and 24 months after surgery. Specimens taken during the procedure were examined and scored for goblet cells, subepithelial thickening, mast cells, and eosinophils. Multiple regression analysis was performed to predict the total score of subjective symptoms before treatment by histopathologic parameters. The correlation between histopathologic parameters and postoperative symptoms was then evaluated. - - - - - RESULTS: Goblet cells were the best predictor correlating with 5 symptoms. Subepithelial thickening correlated with 4 symptoms. Mast cell infiltration correlated with 3 symptoms. Eosinophilic infiltration correlated with only one symptom (P<0.05). - - - - - CONCLUSION: Certain histopathologic parameters in CRS are predictive of favorable response to ESS. - - - - - SIGNIFICANCE: Pathologic evaluation may help the ENT surgeon to predict the persistence of certain CRS symptoms after ESS, even in patients at low risk for surgical failure. - - - - - EBM rating: C-4
Overstretching Expectations May Endanger the Success of the “Millennium Surgery”
Total hip arthroplasty (THA) is an extremely successful treatment strategy. Patient expectations, however, have increased; if not properly guided by surgeons, at present, patients expect next to pain-free restoration of the joint and a fast return to work and sports. While the revision rates after THA also increased in younger patients, knowledge on musculoskeletal loads still remains sparse, and the current recommendations on postoperative rehabilitation are based on expert opinions only. The aim of this study was to unravel biomechanical contact conditions in "working age" (60 years, 67.7 +/- 8.6 years) patients during activities recommended post-THA. We hypothesized that working age patients would show substantially increased hip contact loads compared to older patients. The in vivo joint contact force (F-res) and torsion torque (M-tors), reflecting the main contact load situation, experienced during activities of daily living and sports activities were measured in a unique group of 16 patients with instrumented THA. We summarized patient activities and sports recommendations after THA mentioned within the literature using PubMed (without claim of completeness). The measurements showed that younger working age patients experienced significant (p = 0.050) increased M-tors (21.52 +/- 9.11 Nm) than older retirement age patients (13.99 +/- 7.89 Nm) by walking. Bowling, as a recommended low-impact sport, was associated with F-res of up to 5436 N and M-tors of up to 108 Nm in the working age group, which were higher than the F-res (5276 N) and M-tors (71 Nm) during high-impact soccer. Based on our results, age was proven to be a discriminator in joint loading, with working age patients presenting with increased loads compared to retirement age patients, already during daily activities. The current patient recommendations have led to further increased joint loadings. If THA cannot be delayed in a patient, we propose counselling patients on a carefully considered return to sports, focusing on low-impact activities, as indicated hereby. The findings from this work illustrate the need to provide critical feedback to patient expectations when returning to work and sports activities. Patients returning to more intensive sports activities should be carefully monitored and advised to avoid as much overloading as possible
Surgical cup placement affects the heating up of total joint hip replacements
The long-term success of highly effective total hip arthroplasty (THA) is mainly restricted by aseptic loosening, which is widely associated with friction between the head and cup liner. However, knowledge of the in vivo joint friction and resulting temperature increase is limited. Employing a novel combination of in vivo and in silico technologies, we analyzed the hypothesis that the intraoperatively defined implant orientation defines the individual joint roofing, friction and its associated temperature increase. A total of 38,000 in vivo activity trials from a special group of 10 subjects with instrumented THA implants with an identical material combination were analyzed and showed a significant link between implant orientation, joint kinematics, joint roofing and friction-induced temperature increase but surprisingly not with acting joint contact force magnitude. This combined in vivo and in silico analysis revealed that cup placement in relation to the stem is key to the in vivo joint friction and heating-up of THA. Thus, intraoperative placement, and not only articulating materials, should be the focus of further improvements, especially for young and more active patients
Association of Machine Learning–Based Predictions of Medial Knee Contact Force With Cartilage Loss Over 2.5 Years in Knee Osteoarthritis
Objective: The relationship between in vivo knee load predictions and longitudinal cartilage changes has not been investigated. We undertook this study to develop an equation to predict the medial tibiofemoral contact force (MCF) peak during walking in persons with instrumented knee implants, and to apply this equation to determine the relationship between the predicted MCF peak and cartilage loss in patients with knee osteoarthritis (OA).
Methods: In adults with knee OA (39 women, 8 men; mean ± SD age 61.1 ± 6.8 years), baseline biomechanical gait analyses were performed, and annualized change in medial tibial cartilage volume (mm3 /year) over 2.5 years was determined using magnetic resonance imaging. In a separate sample of patients with force-measuring tibial prostheses (3 women, 6 men; mean ± SD age 70.3 ± 5.2 years), gait data plus in vivo knee loads were used to develop an equation to predict the MCF peak using machine learning. This equation was then applied to the knee OA group, and the relationship between the predicted MCF peak and annualized cartilage volume change was determined.
Results: The MCF peak was best predicted using gait speed, the knee adduction moment peak, and the vertical knee reaction force peak (root mean square error 132.88N; R2 = 0.81, P < 0.001). In participants with knee OA, the predicted MCF peak was related to cartilage volume change (R2 = 0.35, β = -0.119, P < 0.001).
Conclusion: Machine learning was used to develop a novel equation for predicting the MCF peak from external biomechanical parameters. The predicted MCF peak was positively related to medial tibial cartilage volume loss in patients with knee OA
Can electromagnetic fields influence the structure and enzymatic digest of proteins? A critical evaluation of microwave-assisted proteomics protocols
AbstractThis study reevaluates the putative advantages of microwave-assisted tryptic digests compared to conventionally heated protocols performed at the same temperature. An initial investigation of enzyme stability in a temperature range of 37–80°C demonstrated that trypsin activity declines sharply at temperatures above 60°C, regardless if microwave dielectric heating or conventional heating is employed. Tryptic digests of three proteins of different size (bovine serum albumin, cytochrome c and β-casein) were thus performed at 37°C and 50°C using both microwave and conventional heating applying accurate internal fiber-optic probe reaction temperature measurements. The impact of the heating method on protein degradation and peptide fragment generation was analyzed by SDS-PAGE and MALDI-TOF-MS. Time-dependent tryptic digestion of the three proteins and subsequent analysis of the corresponding cleavage products by MALDI-TOF provided virtually identical results for both microwave and conventional heating. In addition, the impact of electromagnetic field strength on the tertiary structure of trypsin and BSA was evaluated by molecular mechanics calculations. These simulations revealed that the applied field in a typical laboratory microwave reactor is 3–4 orders of magnitude too low to induce conformational changes in proteins or enzymes
In vivo load measurements with instrumented implants
Aquatic exercises are widely used for rehabilitation or preventive therapies
in order to enable mobilization and muscle strengthening while minimizing
joint loading of the lower limb. The load reducing effect of water due to
buoyancy is a main advantage compared to exercises on land. However, also drag
forces have to be considered that act opposite to the relative motion of the
body segments and require higher muscle activity. Due to these opposing
effects on joint loading, the load-reducing effect during aquatic exercises
remains unknown. The aim of this study was to quantify the joint loads during
various aquatic exercises and to determine the load reducing effect of water.
Instrumented knee and hip implants with telemetric data transfer were used to
measure the resultant joint contact forces in 12 elderly subjects (6x hip, 6x
knee) in vivo. Different dynamic, weight-bearing and non-weight-bearing
activities were performed by the subjects on land and in chest-high water.
Non-weight-bearing hip and knee flexion/extension was performed at different
velocities and with additional Aquafins. Joint forces during aquatic exercises
ranged between 32 and 396% body weight (BW). Highest forces occurred during
dynamic activities, followed by weight-bearing and slow non-weight-bearing
activities. Compared to the same activities on land, joint forces were reduced
by 36–55% in water with absolute reductions being greater than 100%BW during
weight-bearing and dynamic activities. During non-weight-bearing activities,
high movement velocities and additional Aquafins increased the joint forces by
up to 59% and resulted in joint forces of up to 301%BW. This study confirms
the load reducing effect of water during weight-bearing and dynamic exercises.
Nevertheless, high drag forces result in increased joint contact forces and
indicate greater muscle activity. By the choice of activity, movement velocity
and additional resistive devices joint forces can be modulated individually in
the course of rehabilitation or preventive therapies
Lower-limb internal loading and potential consequences for fracture healing
Introduction: Mechanical loading is known to determine the course of bone fracture healing. We hypothesise that lower limb long bone loading differs with knee flexion angle during walking and frontal knee alignment, which affects fracture healing success.
Materials and methods: Using our musculoskeletal in silico modelling constrained against in vivo data from patients with instrumented knee implants allowed us to assess internal loads in femur and tibia. These internal forces were associated with the clinical outcome of fracture healing in a relevant cohort of 178 extra-articular femur and tibia fractures in patients using a retrospective approach.
Results: Mean peak forces differed with femoral compression (1,330-1,936 N at mid-shaft) amounting to about half of tibial compression (2,299-5,224 N). Mean peak bending moments in the frontal plane were greater in the femur (71-130 Nm) than in the tibia (from 26 to 43 Nm), each increasing proximally. Bending in the sagittal plane showed smaller mean peak bending moments in the femur (-38 to 43 Nm) reaching substantially higher values in the tibia (-63 to -175 Nm) with a peak proximally. Peak torsional moments had opposite directions for the femur (-13 to -40 Nm) versus tibia (15-48 Nm) with an increase towards the proximal end in both. Femoral fractures showed significantly lower scores in the modified Radiological Union Scale for Tibia (mRUST) at last follow-up (p < 0.001) compared to tibial fractures. Specifically, compression (r = 0.304), sagittal bending (r = 0.259), and frontal bending (r = -0.318) showed strong associations (p < 0.001) to mRUST at last follow-up. This was not the case for age, body weight, or localisation alone.
Discussion: This study showed that moments in femur and tibia tend to decrease towards their distal ends. Tibial load components were influenced by knee flexion angle, especially at push-off, while static frontal alignment played a smaller role. Our results indicate that femur and tibia are loaded differently and thus require adapted fracture fixation considering load components rather than just overall load level
TOPICAL ISSUES OF ANTICORRUPTION ENLIGHTENMENT AND ANTICORRUPTION EDUCATION
Objective: to familiarize a wide range of interested persons with the results of the 2nd Siberian Anti-corruption Forum with international participation “Topical issues of anti-corruption enlightenment and anti-corruption education” held on 15-16September 2016 at the Siberian Federal University (Krasnoyarsk).Methods: in the preparation of their presentations, the forum participants used the scientific method of dialectical cognition, and a number of specific scientific methods: historical-legal, systemic-structural, comparative legal, formal logic (deduction, induction, definition and division of concepts), etc.Results: elaboration of proposals on improvement of anti-corruption enlightenment and anti-corruption education. In the forum took part the Vice-rector for social Affairs of SFU, Doctor of Economics, Professor S. I. Mutovin, Director of the Law Institute of SFU, Doctor of Law, Professor I. V. Shishko and Head of Research and Development Department of International Institute for Educational Planning, UNESCO (France), PhD in Education M. Poisson, Head of the Department of Delictology and Criminology of the Law Institute of SFU, Doctor of Law, Professor N. V. Shchedrin, Director of the Center for anti-corruption technologies (Tomsk), PhD in Law S. M. Budatarov, Head of the Center for the Russian Law Studies, Professor of the Heilongjiang University of Harbin (China), PhD in Law Pan Dunmay, Director of the Center for combating corruption and legal expertise of SFU, Associate Professor of the Deparment of Delictology and Criminology of the Law Institute of SFU, PhD in Law I. A. Damm, as well as representatives of public authorities, local governments, civil society institutions, and mass media.Scientific novelty: the forum held interdisciplinary scientific-practical discussion of the key issues of formation of public intolerance towards corruption behavior by means of anti-corruption enlightenment and anti-corruption education. Practical significance: in the ensued scientific discussion, the forum participants put forward a number of proposals for improvement of legal regulation and organization of anti-corruption enlightenment and anti-corruption education in the light of the accumulated experience, including in foreign countries
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