Download the Free Unbound MEDLINE PubMed App to your smartphone or tablet.
Available for iPhone, iPad, iPod touch, and Android.
- C2 pars/pedicle screws in management of craniocervical and upper cervical instability. [Journal Article]
- Asian Spine J 2014 Apr; 8(2):156-60.
A retrospective study.To evaluate the efficacy and the safety of craniocervical and upper cervical stabilization by using C2 pars/pedicle screw fixations.The management of craniocervical and upper cervical instability has progressed over the past two decades due to good achievements in the instrumentation and the increased awareness on spinal anatomy and biomechanics. However, there is insufficient studies or solid conclusions on this topic, thus, we tried to investigate and present our findings.Twenty-two patients were operated upon and were followed up from March 2008 to October 2010. One patient had craniocervical instability (post-surgical), 15 patients had atlantoaxial instability of different etiologies (trauma, tumors, inflammatory and degenerative) and 6 patients had hangman fractures. Patients' ages ranged from 18 to 52 years old. with 5 female patients and 17 male patients.Radiological follow ups performed immediately post-operation showed good screw positioning and complete reductions in nearly all the cases. All patients were followed up for more than one year. Sound fusions were observed among all patients.The use of pars/pedicle screws is a very effective, sound, safe and easy surgical modality for treating craniocervical, atlantoaxial and upper cervical instabilities. Increasing studies for the biomechanics of this important region and longer periods of follow-ups are necessary to document the usefulness of this modality when treating such patients.
- [Biomechanical modelling of the wrist joint]. [English Abstract, Journal Article]
- Z Orthop Unfall 2014 Apr; 152(2):161-9.
Background:The hand represents one of the most complex joint mechanisms of the human body. The hand is also an important communication medium. The spectrum of today's hand injuries reaches from minor damage up to complex traumata with loss of several functional aspects. Enormous subsequent economic costs result. The therapeutic re-establishment of the equilibrium between maximum stress and the actual applied stress is the condition for a lifelong joint function. Material and
Methods:A literature review about biomechanical wrist models was realised. The previous models found in the literature were systematically analysed as well as verifying their suitability for clinical use regarding pathological changes, therapy approaches and modelling/simulation approaches, respectively, of wrist injuries.
Results:The return of the wrist joint biomechanics to the normal condition is a key factor for a successful therapy. Furthermore, it is important for the re-establishment of an unimpaired joint function. Currently, there exist only simplified descriptions and models of the wrist joint, approximated by technical joints and furthermore, they are partially contradictory. Therefore, no uniform validated biomechanical wrist model exists as yet.
Conclusion:Regarding the arising complex clinical problems, however, a valid biomechanical wrist joint model would be necessary as assistance, in order to improve the success of systematised therapies on the basis of computer-aided model-based planning and intervention.
- Role of sost in wnt signal pathway in osteoporosis rats and regulating effect of soybean isoflavones on wnt signal pathway. [JOURNAL ARTICLE]
- Mol Biol Rep 2014 Apr 24.
To explore the mechanism of soybean isoflavones (SI) on OVX-induced osteoporosis, we investigated the effect of SI on Wnt signaling that emerged as a novel key pathway for promoting bone formation. Results showed that SI decreased bone mineral elements loss, improved biomechanics parameters in OVX rats. Wnt3a activation can promote the dissociation of β-catenin complexes, release of β-catenin monomer and inhibition of β-catenin monomer degradation. SI decreased sost mRNA and sclerosteosis protein expression in a dose-dependent manner, and increased β-catenin proteins expression in femur of OVX rats. These data suggest that SI suppresses the canonical Wnt signal in OVX rats, partially through the enhancement of the dickkopf-1 production. OVX results in decreased estrogen level in rats. SI act as inhibitors of Wnt-mediated activation of by competitively binding to LRP5, and subsequently downregulating β-catenin gene.
- On the Iterative Methods of Linearization, Decrease of Order and Dimension of the Karman-Type PDEs. [Journal Article]
- ScientificWorldJournal 2014.:792829.
Iterative methods to achieve a suitable linearization as well as a decrease of the order and dimension of nonlinear partial differential equations of the eighth order into the biharmonic and Poisson-type differential equations with their simultaneous linearization are proposed in this work. Validity and reliability of the obtained results are discussed using computer programs developed by the authors.
- Advancements in identifying biomechanical determinants for abdominal aortic aneurysm rupture. [JOURNAL ARTICLE]
- Vascular 2014 Apr 22.
Abdominal aortic aneurysms are a common health problem and currently the need for surgical intervention is determined based on maximum diameter and growth rate criteria. Since these universal variables often fail to predict accurately every abdominal aortic aneurysms evolution, there is a considerable effort in the literature for other markers to be identified towards individualized rupture risk estimations and growth rate predictions. To this effort, biomechanical tools have been extensively used since abdominal aortic aneurysm rupture is in fact a material failure of the diseased arterial wall to compensate the stress acting on it. The peak wall stress, the role of the unique geometry of every individual abdominal aortic aneurysm as well as the mechanical properties and the local strength of the degenerated aneurysmal wall, all confer to rupture risk. In this review article, the assessment of these variables through mechanical testing, advanced imaging and computational modeling is reviewed and the clinical perspective is discussed.
- Mechanical characterization of human gastrocolic ligament until failure. [JOURNAL ARTICLE]
- J Appl Biomater Funct Mater 2014 Apr 18.:0.
Road accidents can lead to abdominal injuries ranging from severe to lethal, that include hemorrhage of organs and their attachment system. A good understanding and prediction of abdominal injuries therefore requires investigation of the mechanical properties of the attachment systems of abdominal organs. In particular, the gastrocolic ligament (GCL) is one major link between the stomach and the transverse colon. This study aims to investigate the mechanical properties of the GCL under very low and high strain rate uniaxial tensile tests until failure. Thirty-five GCL samples were dissected from 7 embalmed cadavers and tested at a rate of 1 mm/s and 1 m/s. Incidence of freezing was also evaluated. The mechanical response of GCL samples showed an approximately bilinear curve. Within the first linear region (less than 5% of ligament strain), the apparent elastic modulus was estimated at 247±144 kPa, while in the second region, it was estimated at 690±282 kPa. The average failure stress (σfail) and failure strain (εfail) were 131.6±50 kPa and 29%±8%, respectively. High strain rate loading also showed high sensitivity to strain rate. The estimated GCL mechanical properties in this study can be implemented in finite element models of the abdomen to further investigate the mechanical contribution of the organ attachment system under traumatic loading conditions.
- Mechanomics: an emerging field between biology and biomechanics. [JOURNAL ARTICLE]
- Protein Cell 2014 Apr 23.
Cells sense various in vivo mechanical stimuli, which initiate downstream signaling to mechanical forces. While a body of evidences is presented on the impact of limited mechanical regulators in past decades, the mechanisms how biomechanical responses globally affect cell function need to be addressed. Complexity and diversity of in vivo mechanical clues present distinct patterns of shear flow, tensile stretch, or mechanical compression with various parametric combination of its magnitude, duration, or frequency. Thus, it is required to understand, from the viewpoint of mechanobiology, what mechanical features of cells are, why mechanical properties are different among distinct cell types, and how forces are transduced to downstream biochemical signals. Meanwhile, those in vitro isolated mechanical stimuli are usually coupled together in vivo, suggesting that the different factors that are in effect individually could be canceled out or orchestrated with each other. Evidently, omics analysis, a powerful tool in the field of system biology, is advantageous to combine with mechanobiology and then to map the full-set of mechanically sensitive proteins and transcripts encoded by its genome. This new emerging field, namely mechanomics, makes it possible to elucidate the global responses under systematically-varied mechanical stimuli. This review discusses the current advances in the related fields of mechanomics and elaborates how cells sense external forces and activate the biological responses.
- Characterization of Complex, Co-Adapted Skeletal Biomechanics Phenotypes: A Needed Paradigm Shift in the Genetics of Bone Structure and Function. [JOURNAL ARTICLE]
- Curr Osteoporos Rep 2014 Apr 23.
The genetic architecture of skeletal biomechanical performance has tremendous potential to advance our knowledge of the biological mechanisms that drive variation in skeletal fragility and osteoporosis risk. Research using traditional approaches that focus on specific gene pathways is increasing our understanding of how and to what degree those pathways may affect population-level variation in fracture susceptibility, and shows that known pathways may affect bone fragility through unsuspected mechanisms. Non-traditional approaches that incorporate a new appreciation for the degree to which bone traits co-adapt to functional loading environments, using a wide variety of redundant compensatory mechanisms to meet both physiological and mechanical demands, represent a radical departure from the dominant reductionist paradigm and have the potential to rapidly advance our understanding of bone fragility and identification of new targets for therapeutic intervention.
- Validity and reliability of the 45-15 test for aerobic fitness in young soccer players. [Journal Article]
- Int J Sports Physiol Perform 2014 May; 9(3):525-31.
The aim of this study was to examine the reliability and validity of a popular field test for aerobic fitness used in soccer (45-15) in Italy. Alternating progressive 45-s runs with 15 s passive recovery until exhaustion, the test considers peak speed (PS) as a reflection of maximal aerobic speed (MAS). The validity and reliability of the 45-15 was assessed in 18 young male soccer players (age 16.7 ± 1.8 y, body mass 70 ± 7.45 kg, height 177 ± 0.5 cm, 55.62 ± 5.56 mL · kg1 · min1) submitted to laboratory testing for aerobic fitness and repeatedly to the 45-15. Results showed that 45-15 PS was significantly related to VO2max (r = .80, P < .001, 95%CI .47-.93) and MAS (r = .78, P = .001, 95%CI .43-.93). No significant bias between MAS 45-15 PS (P = .11) was found during the measurement-consistency study. Receiver-operating-characteristic (ROC) analysis showed that 45-15 PS was sensitive in detecting VO2max changes in subjects as revealed by area under the curve (.97; 95%CI .73-1). Players with peak 45-15 speed equal to or above 16.5 km/h (ie, ROC cutoff) may be considered to have good aerobic fitness. In light of this study's findings, the 45-15 test may be considered a reliable and valid test to evaluate meaningful information to direct generic aerobic training in soccer.
- Effect of running retraining on pain, function, and lower-extremity biomechanics in a female runner with iliotibial band syndrome. [Journal Article]
- J Sport Rehabil 2014 May; 23(2):145-57.