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Mechanical compression

Jacques Pécréaux, Stefanie Redemann, Zahraa Alayan, Benjamin Mercat, Sylvain Pastezeur, Carlos Garzon-Coral, Anthony A Hyman, Jonathon Howard
Precise positioning of the mitotic spindle is important for specifying the plane of cell division, which in turn determines how the cytoplasmic contents of the mother cell are partitioned into the daughter cells, and how the daughters are positioned within the tissue. During metaphase in the early Caenorhabditis elegans embryo, the spindle is aligned and centered on the anterior-posterior axis by a microtubule-dependent machinery that exerts restoring forces when the spindle is displaced from the center. To investigate the accuracy and stability of centering, we tracked the position and orientation of the mitotic spindle during the first cell division with high temporal and spatial resolution...
October 18, 2016: Biophysical Journal
Triantafyllos Stylianopoulos
Tumor progression and response to treatment is determined in large part by the generation of mechanical stresses that stem from both the solid and the fluid phase of the tumor. Furthermore, elevated solid stress levels can regulate fluid stresses by compressing intratumoral blood and lymphatic vessels. Blood vessel compression reduces tumor perfusion, while compression of lymphatic vessels hinders the ability of the tumor to drain excessive fluid from its interstitial space contributing to the uniform elevation of the interstitial fluid pressure...
October 19, 2016: Journal of Biomechanical Engineering
Mouritz N Svenson, Randall E Youngman, Yuanzheng Yue, Sylwester J Rzoska, Michal Bockowski, Lars R Jensen, Morten M Smedskjaer
The structure and properties of glass can be modified through compression near the glass transition temperature (Tg), and such modified structure and properties can be maintained at ambient temperature and pressure. However, once the compressed glass undergoes annealing near Tg at ambient pressure, the modified structure and properties will relax. The challenging question is how the property relaxation is correlated with both the local and the medium-range structural relaxation. In this paper, we answer this question by studying the volume (density) and structural relaxation of a sodium borate glass that has first been pressure-quenched from its Tg at 1 GPa, and then annealed at ambient pressure under different temperature-time conditions...
October 19, 2016: Physical Chemistry Chemical Physics: PCCP
Gehan F Balata, Ahmad S Zidan, Mohamad As Abourehab, Ebtessam A Essa
The objective of this research was to improve the dissolution of simvastatin and to incorporate it in rapid disintegrating tablets (RDTs) with an optimized disintegration and dissolution characteristics. Polyoxyethylene-polypropylene block copolymer (poloxamer 188) was employed as a hydrophilic carrier to prepare simvastatin solid dispersions (SDs). Fourier transform infrared spectroscopy, differential scanning calorimetry (DSC) and X-ray diffractometry were employed to understand the interaction between the drug and the carrier in the solid state...
2016: Drug Design, Development and Therapy
Lukasz Szarpak, Zenon Truszewski, Lukasz Czyzewski, Michael Frass, Oliver Robak
INTRODUCTION: European Resuscitation Council as well as American Heart Association guidelines for cardiopulmonary resuscitation (CPR) stress the importance of uninterrupted and effective chest compressions (CCs). Manual CPR decreases in quality of CCs over time because of fatigue which impacts outcome. We report the first study with the Lifeline ARM automated CC device for providing uninterrupted CCs. METHODS: Seventy-eight paramedics participated in this randomized, crossover, manikin trial...
October 7, 2016: American Journal of Emergency Medicine
Jonathan T Kaplan, Corey P Neu, Hicham Drissi, Nancy C Emery, David M Pierce
Osteoarthritis and articular cartilage injuries are common conditions in human joints and a frequent cause of pain and disability. Unfortunately, cartilage is avascular and has limited capabilities for self-repair. Despite the societal impact, there is little information on the dynamic process of cartilage degeneration. We performed a series of cyclic unconfined compression tests motivated by in vivo loading conditions and designed to generate mechanical fatigue. We examined the functional (both stress-stretch and creep) responses of the tissue after recovery from a specified number of loading cycles, as well as histology and second harmonic generation microscopy images...
October 1, 2016: Journal of the Mechanical Behavior of Biomedical Materials
Utku Kandemir, Safa Herfat, Mary Herzog, Paul Viscogliosi, Murat Pekmezci
OBJECTIVES: The goal of this study is to compare the fatigue strength of a locking intramedullary nail (LN) construct to a double locking plate (DLP) construct in comminuted proximal extra-articular tibia fractures. METHODS: Eight pairs of fresh frozen cadaveric tibias with low bone mineral density (Age: 80 ± 7 (SD) years, T-score: -2.3 ± 1.2) were used. One tibia from each pair was fixed with LN while the contralateral side was fixed with DLP for complex extra-articular multifragmentary, metaphyseal fractures (simulating OTA41-A3...
October 7, 2016: Journal of Orthopaedic Trauma
Li Li, Yang Lu, Min Li, Xunwei Liu, Peng Jin, Lijun Wang, Gang Sun
STUDY DESIGN: A retrospective study. SUMMARY OF BACKGROUND DATA: Percutaneous vertebroplasty (PV) changes mechanical stress of vertebral column and can cause recurrent pain at the treated level. However, there were a few reports on the therapeutic effects of the repeat PV for patients with recurrent pain at the treated level. OBJECTIVE: To evaluate the therapeutic effects of repeat PV at previously treated vertebral level for patients with osteoporotic vertebral compression fractures (OVCFs) having recurrent pain after initial PV...
November 2016: Clinical Spine Surgery
Weihua Xie, Songhe Meng, Hua Jin, Chong Du, Libin Wang, Tao Peng, Fabrizio Scarpa, Chenghai Xu
This paper presents a simple methodology to perform a high temperature coupled thermo-mechanical test using ultra-high temperature ceramic material specimens (UHTCs), which are equipped with chemical composition gratings sensors (CCGs). The methodology also considers the presence of coupled loading within the response provided by the CCG sensors. The theoretical strain of the UHTCs specimens calculated with this technique shows a maximum relative error of 2.15% between the analytical and experimental data. To further verify the validity of the results from the tests, a Finite Element (FE) model has been developed to simulate the temperature, stress and strain fields within the UHTC structure equipped with the CCG...
October 13, 2016: Sensors
Jason Suh, Amishi Desai, Anish Desai, Josephine Dela Cruz, Anusiyanthan Mariampillai, Alexander Hindenburg
Venous thromboembolism (VTE) remains the number one preventable cause of hospital acquired mortality and morbidity. Each year, more than 12 million patients are at risk for VTE. The delivery of appropriate and timely VTE prophylaxis is still suboptimal in many healthcare institutions and can lead to increased readmissions, morbidity, as well as costs. To clarify this issue further, we performed a retrospective case control study at our institution to determine if poor adherence to the VTE prophylaxis guidelines could lead to an increase in VTE events...
October 17, 2016: Journal of Thrombosis and Thrombolysis
Christian Svendsen Juhl, Martin Ballegaard, Morten H Bestle, Peer Tfelt-Hansen
Meralgia paresthetica (MP) is a mononeuropathy of the lateral femoral cutaneous nerve (LFCN) caused by external compression of the nerve during its course close to the anterior superior iliac spine. We present a case of a patient with acute respiratory distress induced by Legionella pneumonia who was admitted to the intensive care unit (ICU) for mechanical ventilation. In the ICU, the patient received one session of prone position ventilation for 8.5 consecutive hours. At evaluation six months later, the patient reported persistent bilateral numbness of the anterolateral thigh, which he complained had begun right after he woke up at the ICU...
2016: Case Reports in Critical Care
Liangfa Hu, Morgan O'Neil, Veysel Erturun, Rogelio Benitez, Gwénaëlle Proust, Ibrahim Karaman, Miladin Radovic
The prospect of extending existing metal-ceramic composites to those with the compositions that are far from thermodynamic equilibrium is examined. A current and pressure-assisted, rapid infiltration is proposed to fabricate composites, consisting of reactive metallic and ceramic phases with controlled microstructure and tunable properties. An aluminum (Al) alloy/Ti2AlC composite is selected as an example of the far-from-equilibrium systems to fabricate, because Ti2AlC exists only in a narrow region of the Ti-Al-C phase diagram and readily reacts with Al...
October 18, 2016: Scientific Reports
O V Kim, R I Litvinov, J Chen, D Z Chen, J W Weisel, M S Alber
Fibrin and collagen as well as their combinations play an important biological role in tissue regeneration and are widely employed in surgery as fleeces or sealants and in bioengineering as tissue scaffolds. Earlier studies demonstrated that fibrin-collagen composite networks displayed improved tensile mechanical properties compared to the isolated protein matrices. Unlike previous studies, here unconfined compression was applied to a fibrin-collagen filamentous polymer composite matrix to study its structural and mechanical responses to compressive deformation...
October 14, 2016: Matrix Biology: Journal of the International Society for Matrix Biology
J Mesquita-Guimarães, M A Leite, J C M Souza, B Henriques, F S Silva, D Hotza, A R Boccaccini, M C Fredel
In this work, TiO2 ceramic scaffolds were fabricated by the replica method using polyurethane (PU) sponges. Suspensions with high solid content were used to achieve scaffolds with improved mechanical behavior. TiO2 ceramic suspensions were optimized by rheological studies using different additives. It was found that the composition with 0.5 wt% Darvan enhanced the covering of the sponge struts. PU sponges of 45 to 80 ppi (pore per inch) were well coated without clogging pores. A thermal treatment with varying holding times, temperatures and heating rates was adjusted...
October 17, 2016: Journal of Biomedical Materials Research. Part A
Sang Min Park, Haemin Jeong, Kyung-Soon Hong, Christopher Kim
BACKGROUND: In a patient underwent aortic valve replacement (AVR) due to bicuspid aortic valve (BAV) insufficiency without marked dilation of ascending aorta, the development of delayed-typed aneurysmal complication of ascending aorta has been often reported because the dilated aorta tends to grow insidiously with age. CASE SUMMARY: A 58-year-old man who underwent AVR with mechanical valve due to severe aortic regurgitation secondary to BAV 7 years previously presented with exertional chest discomfort for 1 year...
October 2016: Medicine (Baltimore)
Masaaki Ikeda, Yoshitaka Yoshimura, Takashi Kikuiri, Mino Matsuno, Tomokazu Hasegawa, Kumu Fukushima, Takako Hayakawa, Hajime Minamikawa, Kuniaki Suzuki, Junichiro Iida
Bone remodeling is an important factor in orthodontic tooth movement. During orthodontic treatment, osteoclasts are subjected to various mechanical stimuli, and this promotes or inhibits osteoclast differentiation and fusion. It has been previously reported that the release from tensile force induces osteoclast differentiation. However, little is known about how release from compressive force affects osteoclasts. The present study investigated the effects of release from compressive force on osteoclasts. The number of tartrate‑resistant acid phosphatase (TRAP)‑positive multinucleated osteoclasts derived from RAW264...
October 5, 2016: Molecular Medicine Reports
Toshitake Furusawa, Tsutomu Minatoya, Toshimitsu Okudera, Yasuo Sakai, Tomohiro Sato, Yuta Matsushima, Hidero Unuma
BACKGROUND: In an attempt to prepare scaffolds with porosity and compressive strength as high as possible, we prepared porous β-tricalcium phosphate (TCP) scaffolds and coated them with regenerative medicine-grade gelatin. The effects of the gelatin coating on the compressive strength and in vivo osteoblast compatibility were investigated. METHODS: Porous β-TCP scaffolds were prepared and coated with up to 3 mass% gelatin, and then subjected to thermal cross-linking...
December 2016: Int J Implant Dent
Luca Lombardo, Enrico Sacchi, Maria Larosa, Francesco Mollica, Valentina Mazzanti, Giorgio Alfredo Spedicato, Giuseppe Siciliani
BACKGROUND: The aim of this study is to evaluate the mechanical properties of the screws used for rapid expansion of the upper jaw. METHODS: Ten types of expansion screw were assessed, seven with four arms: Lancer Philosophy 1, Dentaurum Hyrax Click Medium, Forestadent Anatomic Expander type "S", Forestadent Anatomic Expander type "S" for narrow palates, Forestadent Memory, Leone A 2620-10 with telescopic guide, and Leone A 0630-10 with orthogonal arms; and three with two arms: Dentaurum Variety S...
December 2016: Progress in Orthodontics
Constantin von Kirschbaum, Robert Gürkov
Introduction. Vestibular schwannomas (VS) are benign tumours of the vestibular nerve and can lead to hearing loss, tinnitus, vertigo, facial palsy, and brainstem compression. Audiovestibular diagnostic tests are essential for detection and treatment planning. Methods. Medline was used to perform a systematic literature review with regard to how audiovestibular test parameters correlate with symptoms, tumour size, and tumour location. Results. The auditory brainstem response can be used to diagnose retrocochlear lesions caused by VS...
2016: BioMed Research International
Yu-Fu Wang, Carlos M Barrera, Edward A Dauer, Weiyong Gu, Fotios Andreopoulos, C-Y Charles Huang
One of the key challenges in porous scaffold design is to create a porous structure with desired mechanical function and mass transport properties which support delivery of biofactors and development of function tissue substitute. In recent years, polyurethane (PU) has become one of the most popular biomaterials in various tissue engineering fields. However, there are no studies fully investigating the relations between porosity and both mass transport and mechanical properties of PU porous scaffolds. In this paper, we fabricated PU scaffolds by combining phase inversion and salt (sodium chloride) leaching methods...
September 23, 2016: Journal of the Mechanical Behavior of Biomedical Materials
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