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MEDICAL SCIENCES (1857 journals)                  1 2 3 4 5 6 7 8 | Last

Showing 1 - 200 of 3562 Journals sorted alphabetically
16 de Abril     Open Access  
AADE in Practice     Hybrid Journal   (Followers: 4)
ABCS Health Sciences     Open Access   (Followers: 1)
Abia State University Medical Students' Association Journal     Full-text available via subscription  
ACIMED     Open Access   (Followers: 1)
ACS Medicinal Chemistry Letters     Full-text available via subscription   (Followers: 40)
Acta Bio Medica     Full-text available via subscription   (Followers: 2)
Acta Bioethica     Open Access  
Acta Bioquimica Clinica Latinoamericana     Open Access   (Followers: 1)
Acta Facultatis Medicae Naissensis     Open Access  
Acta Informatica Medica     Open Access   (Followers: 1)
Acta Medica Bulgarica     Open Access  
Acta Medica Colombiana     Open Access   (Followers: 1)
Acta Médica Costarricense     Open Access   (Followers: 2)
Acta Medica Indonesiana     Open Access  
Acta medica Lituanica     Open Access  
Acta Medica Marisiensis     Open Access  
Acta Medica Martiniana     Open Access  
Acta Medica Nagasakiensia     Open Access  
Acta Medica Peruana     Open Access   (Followers: 2)
Acta Médica Portuguesa     Open Access  
Acta Medica Saliniana     Open Access  
Acta Scientiarum. Health Sciences     Open Access   (Followers: 1)
Acupuncture & Electro-Therapeutics Research     Full-text available via subscription   (Followers: 3)
Acupuncture and Natural Medicine     Open Access  
Addiction Science & Clinical Practice     Open Access   (Followers: 6)
Addictive Behaviors Reports     Open Access   (Followers: 7)
Advanced Health Care Technologies     Open Access   (Followers: 4)
Advanced Science, Engineering and Medicine     Partially Free   (Followers: 7)
Advances in Bioscience and Clinical Medicine     Open Access   (Followers: 5)
Advances in Clinical Chemistry     Full-text available via subscription   (Followers: 28)
Advances in Life Course Research     Hybrid Journal   (Followers: 8)
Advances in Lipobiology     Full-text available via subscription   (Followers: 1)
Advances in Medical Education and Practice     Open Access   (Followers: 25)
Advances in Medical Sciences     Hybrid Journal   (Followers: 6)
Advances in Medicinal Chemistry     Full-text available via subscription   (Followers: 5)
Advances in Medicine     Open Access   (Followers: 2)
Advances in Microbial Physiology     Full-text available via subscription   (Followers: 4)
Advances in Molecular Oncology     Open Access   (Followers: 2)
Advances in Molecular Toxicology     Full-text available via subscription   (Followers: 7)
Advances in Parkinson's Disease     Open Access  
Advances in Phytomedicine     Full-text available via subscription  
Advances in Preventive Medicine     Open Access   (Followers: 5)
Advances in Protein Chemistry and Structural Biology     Full-text available via subscription   (Followers: 18)
Advances in Therapy     Hybrid Journal   (Followers: 5)
Advances in Veterinary Science and Comparative Medicine     Full-text available via subscription   (Followers: 13)
Advances in Virus Research     Full-text available via subscription   (Followers: 5)
Advances in Wound Care     Hybrid Journal   (Followers: 10)
African Health Sciences     Open Access   (Followers: 2)
African Journal of Biomedical Research     Open Access  
African Journal of Clinical and Experimental Microbiology     Open Access   (Followers: 1)
African Journal of Laboratory Medicine     Open Access   (Followers: 2)
African Journal of Medical and Health Sciences     Open Access   (Followers: 2)
African Journal of Trauma     Open Access  
Afrimedic Journal     Open Access   (Followers: 2)
Aggiornamenti CIO     Hybrid Journal   (Followers: 1)
AIDS Research and Human Retroviruses     Hybrid Journal   (Followers: 8)
AJOB Primary Research     Partially Free   (Followers: 3)
AJSP: Reviews & Reports     Hybrid Journal  
Aktuelle Ernährungsmedizin     Hybrid Journal   (Followers: 4)
Al-Azhar Assiut Medical Journal     Open Access  
Alexandria Journal of Medicine     Open Access   (Followers: 1)
Allgemeine Homöopathische Zeitung     Hybrid Journal   (Followers: 2)
Alpha Omegan     Full-text available via subscription  
ALTEX : Alternatives to Animal Experimentation     Open Access   (Followers: 3)
American Journal of Biomedical Engineering     Open Access   (Followers: 12)
American Journal of Biomedical Research     Open Access   (Followers: 2)
American Journal of Biomedicine     Full-text available via subscription   (Followers: 7)
American Journal of Chinese Medicine, The     Hybrid Journal   (Followers: 4)
American Journal of Clinical Medicine Research     Open Access   (Followers: 6)
American Journal of Family Therapy     Hybrid Journal   (Followers: 11)
American Journal of Law & Medicine     Full-text available via subscription   (Followers: 10)
American Journal of Lifestyle Medicine     Hybrid Journal   (Followers: 5)
American Journal of Managed Care     Full-text available via subscription   (Followers: 11)
American Journal of Medical Case Reports     Open Access   (Followers: 1)
American Journal of Medical Sciences and Medicine     Open Access   (Followers: 3)
American Journal of Medicine     Hybrid Journal   (Followers: 42)
American Journal of Medicine and Medical Sciences     Open Access   (Followers: 1)
American Journal of Medicine Studies     Open Access  
American Journal of Medicine Supplements     Full-text available via subscription   (Followers: 3)
American Journal of the Medical Sciences     Hybrid Journal   (Followers: 12)
American Journal on Addictions     Hybrid Journal   (Followers: 7)
American medical news     Free   (Followers: 3)
American Medical Writers Association Journal     Full-text available via subscription   (Followers: 2)
Amyloid: The Journal of Protein Folding Disorders     Hybrid Journal   (Followers: 5)
Anales de la Facultad de Medicina     Open Access  
Anales de la Facultad de Medicina, Universidad de la República, Uruguay     Open Access  
Anales del Sistema Sanitario de Navarra     Open Access   (Followers: 1)
Analgesia & Resuscitation : Current Research     Hybrid Journal   (Followers: 4)
Anatomical Science International     Hybrid Journal   (Followers: 2)
Anatomical Sciences Education     Hybrid Journal   (Followers: 1)
Anatomy Research International     Open Access   (Followers: 2)
Angewandte Schmerztherapie und Palliativmedizin     Hybrid Journal  
Angiogenesis     Hybrid Journal   (Followers: 3)
Ankara Medical Journal     Open Access   (Followers: 2)
Annales de Pathologie     Full-text available via subscription  
Annales françaises d'Oto-rhino-laryngologie et de Pathologie Cervico-faciale     Full-text available via subscription   (Followers: 3)
Annals of African Medicine     Open Access   (Followers: 1)
Annals of Anatomy - Anatomischer Anzeiger     Hybrid Journal   (Followers: 2)
Annals of Bioanthropology     Open Access   (Followers: 4)
Annals of Biomedical Engineering     Hybrid Journal   (Followers: 18)
Annals of Biomedical Sciences     Full-text available via subscription   (Followers: 3)
Annals of Clinical Microbiology and Antimicrobials     Open Access   (Followers: 9)
Annals of Family Medicine     Open Access   (Followers: 12)
Annals of Fundeni Hospital     Open Access   (Followers: 1)
Annals of Ibadan Postgraduate Medicine     Open Access  
Annals of Medical and Health Sciences Research     Open Access   (Followers: 7)
Annals of Medicine     Hybrid Journal   (Followers: 12)
Annals of Medicine and Surgery     Open Access   (Followers: 7)
Annals of Microbiology     Hybrid Journal   (Followers: 10)
Annals of Nigerian Medicine     Open Access   (Followers: 1)
Annals of Saudi Medicine     Open Access  
Annals of the New York Academy of Sciences     Hybrid Journal   (Followers: 5)
Annals of The Royal College of Surgeons of England     Full-text available via subscription   (Followers: 3)
Annual Reports in Medicinal Chemistry     Full-text available via subscription   (Followers: 7)
Annual Reports on NMR Spectroscopy     Full-text available via subscription   (Followers: 4)
Annual Review of Medicine     Full-text available via subscription   (Followers: 17)
Anthropological Review     Open Access   (Followers: 22)
Anthropologie et santé     Open Access   (Followers: 5)
Antibiotics     Open Access   (Followers: 9)
Antibodies     Open Access   (Followers: 2)
Antibody Technology Journal     Open Access   (Followers: 1)
Anuradhapura Medical Journal     Open Access  
Anwer Khan Modern Medical College Journal     Open Access   (Followers: 2)
Apmis     Hybrid Journal   (Followers: 1)
Apparence(s)     Open Access   (Followers: 1)
Applied Clinical Informatics     Hybrid Journal   (Followers: 2)
Applied Clinical Research, Clinical Trials and Regulatory Affairs     Hybrid Journal  
Applied Medical Informatics     Open Access   (Followers: 10)
Arab Journal of Nephrology and Transplantation     Open Access   (Followers: 1)
Arak Medical University Journal     Open Access  
Archive of Clinical Medicine     Open Access   (Followers: 1)
Archive of Community Health     Open Access  
Archives of Biomedical Sciences     Open Access   (Followers: 7)
Archives of Medical and Biomedical Research     Open Access   (Followers: 3)
Archives of Medical Laboratory Sciences     Open Access   (Followers: 1)
Archives of Medicine and Health Sciences     Open Access   (Followers: 3)
Archives of Trauma Research     Open Access   (Followers: 2)
Archivos de Medicina (Manizales)     Open Access  
ArgoSpine News & Journal     Hybrid Journal  
Arquivos Brasileiros de Oftalmologia     Open Access  
Arquivos de Ciências da Saúde     Open Access  
Arquivos de Medicina     Open Access  
Ars Medica : Revista de Ciencias Médicas     Open Access  
ARS Medica Tomitana     Open Access   (Followers: 1)
Art Therapy: Journal of the American Art Therapy Association     Full-text available via subscription   (Followers: 11)
Arterial Hypertension     Open Access   (Followers: 1)
Artificial Intelligence in Medicine     Hybrid Journal   (Followers: 12)
Artificial Organs     Hybrid Journal   (Followers: 1)
Asia Pacific Family Medicine     Open Access   (Followers: 1)
Asia Pacific Journal of Clinical Nutrition     Full-text available via subscription   (Followers: 10)
Asia Pacific Journal of Clinical Trials : Nervous System Diseases     Open Access  
Asian Bioethics Review     Full-text available via subscription   (Followers: 3)
Asian Journal of Cell Biology     Open Access   (Followers: 5)
Asian Journal of Health     Open Access   (Followers: 3)
Asian Journal of Medical and Biological Research     Open Access   (Followers: 3)
Asian Journal of Medical and Pharmaceutical Researches     Open Access   (Followers: 1)
Asian Journal of Medical Sciences     Open Access   (Followers: 1)
Asian Journal of Scientific Research     Open Access   (Followers: 3)
Asian Journal of Transfusion Science     Open Access   (Followers: 1)
Asian Medicine     Hybrid Journal   (Followers: 5)
Asian Pacific Journal of Cancer Prevention     Open Access  
ASPIRATOR : Journal of Vector-borne Disease Studies     Open Access  
Astrocyte     Open Access  
Atención Familiar     Open Access  
Atención Primaria     Open Access   (Followers: 1)
Audiology - Communication Research     Open Access   (Followers: 8)
Auris Nasus Larynx     Full-text available via subscription  
Australian Coeliac     Full-text available via subscription   (Followers: 1)
Australian Family Physician     Full-text available via subscription   (Followers: 3)
Australian Journal of Medical Science     Full-text available via subscription   (Followers: 1)
Autopsy and Case Reports     Open Access  
Aviation, Space, and Environmental Medicine     Full-text available via subscription   (Followers: 10)
Avicenna     Open Access   (Followers: 3)
Avicenna Journal of Medicine     Open Access   (Followers: 1)
Bangabandhu Sheikh Mujib Medical University Journal     Open Access   (Followers: 1)
Bangladesh Journal of Anatomy     Open Access   (Followers: 1)
Bangladesh Journal of Bioethics     Open Access  
Bangladesh Journal of Medical Biochemistry     Open Access   (Followers: 3)
Bangladesh Journal of Medical Education     Open Access   (Followers: 2)
Bangladesh Journal of Medical Microbiology     Open Access   (Followers: 3)
Bangladesh Journal of Medical Physics     Open Access  
Bangladesh Journal of Medical Science     Open Access  
Bangladesh Journal of Medicine     Open Access   (Followers: 1)
Bangladesh Journal of Physiology and Pharmacology     Open Access  
Bangladesh Journal of Scientific Research     Open Access   (Followers: 1)
Bangladesh Medical Journal     Open Access  
Bangladesh Medical Journal Khulna     Open Access  
Basal Ganglia     Hybrid Journal  
Basic Sciences of Medicine     Open Access   (Followers: 2)
BBA Clinical     Open Access  
BC Medical Journal     Free  
Benha Medical Journal     Open Access  
Bijblijven     Hybrid Journal  
Bijzijn     Hybrid Journal   (Followers: 2)
Bijzijn XL     Hybrid Journal   (Followers: 1)
Bio-Algorithms and Med-Systems     Hybrid Journal   (Followers: 1)
BioDiscovery     Open Access   (Followers: 2)
Bioelectromagnetics     Hybrid Journal   (Followers: 1)
Bioengineering & Translational Medicine     Open Access  

        1 2 3 4 5 6 7 8 | Last

Journal Cover Annals of Biomedical Engineering
  [SJR: 1.182]   [H-I: 94]   [18 followers]  Follow
   Hybrid Journal Hybrid journal (It can contain Open Access articles)
   ISSN (Print) 1573-9686 - ISSN (Online) 0090-6964
   Published by Springer-Verlag Homepage  [2351 journals]
  • Eliminating Regurgitation Reduces Fibrotic Remodeling of Functional Mitral
           Regurgitation Conditioned Valves
    • Authors: Patrick S. Connell; Dragoslava P. Vekilov; Christine M. Diaz; Seulgi E. Kim; K. Jane Grande-Allen
      Pages: 670 - 683
      Abstract: Functional mitral regurgitation (FMR) is an insidious and poorly understood condition affecting patients with myocardial disease. While current treatments reduce regurgitation, their ability to reverse mitral valve pathology is unclear. We utilized a pseudo-physiological flow loop to study how repair impacted valve composition. Porcine mitral valves were cultured in control geometry (native papillary muscle position and annular area) or high-tension FMR geometry (5 mm apical and 5 mm lateral displacement of papillary muscles, 65% increased annular area) for 2 weeks. To mimic repair, a reversal condition was created by returning one-week FMR conditioned valves to a non-regurgitant geometry and culturing for 1 week. Valve composition and material properties were analyzed. After two-week culture, FMR conditioned tissues were stiffer and stronger than control and underwent extensive fibrotic remodeling, with increased prolyl-4-hydroxylase, lysyl oxidase, matrix metalloproteinase-1, and decorin. The reversal condition displayed a heterogeneous, leaflet- and orientation-dependent response. Reversal-conditioned anterior leaflets and circumferential tissue sections continued to have significant fibrotic remodeling compared to control, whereas reversal-conditioned posterior leaflets, chordae tendineae, and radial tissue sections had significantly decreased remodeling compared to FMR-conditioned tissues. These findings suggest current repairs only partially reverse pathology, underscoring the need for innovation in the treatment of FMR.
      PubDate: 2018-05-01
      DOI: 10.1007/s10439-018-1987-9
      Issue No: Vol. 46, No. 5 (2018)
  • Nitinol Stents in the Femoropopliteal Artery: A Mechanical Perspective on
           Material, Design, and Performance
    • Authors: Kaspars Maleckis; Eric Anttila; Paul Aylward; William Poulson; Anastasia Desyatova; Jason MacTaggart; Alexey Kamenskiy
      Pages: 684 - 704
      Abstract: Endovascular stenting has matured into a commonly used treatment for peripheral arterial disease (PAD) due to its minimally invasive nature and associated reductions in short-term morbidity and mortality. The mechanical properties of the superelastic Nitinol alloy have played a major role in the explosion of peripheral artery stenting, with modern stents demonstrating reasonable resilience and durability. Yet in the superficial femoral and popliteal arteries, even the newest generation Nitinol stents continue to demonstrate clinical outcomes that leave significant room for improvement. Restenosis and progression of native arterial disease often lead to recurrence of symptoms and reinterventions that increase morbidity and health care expenditures. One of the main factors thought to be associated with stent failure in the femoropopliteal artery (FPA) is the unique and highly dynamic mechanical environment of the lower limb. Clinical and experimental data demonstrate that the FPA undergoes significant deformations with limb flexion. It is hypothesized that the inability of many existing stent designs to conform to these deformations likely plays a role in reconstruction failure, as repetitive movements of the leg and thigh combine with mechanical mismatch between the artery and the stent and result in mechanical damage to both the artery and the stent. In this review we will identify challenges and provide a mechanical perspective of FPA stenting, and then discuss current research directions with promise to provide a better understanding of Nitinol, specific features of stent design, and improved characterization of the biomechanical environment of the FPA to facilitate development of better stents for patients with PAD.
      PubDate: 2018-05-01
      DOI: 10.1007/s10439-018-1990-1
      Issue No: Vol. 46, No. 5 (2018)
  • The Turning Point for Morphomechanical Remodeling During Complete
           Intestinal Obstruction in Rats Occurs After 12–24 h
    • Authors: Daming Sun; Jingbo Zhao; Donghua Liao; Zhiyong Huang; Hans Gregersen
      Pages: 705 - 716
      Abstract: Intestinal obstruction prompts luminal dilation and wall remodeling proximal to the site of obstruction. Studies on temporal and spatial morphomechanical remodeling are needed for comprehending the pathophysiology of acute intestinal obstruction. The aim was to estimate the no-load and zero-stress morphomechanical properties in circumferential and longitudinal direction at 0, 6, 12, 24, 36, and 48 h after complete intestinal obstruction. Obstruction of the distal ileum was created surgically by placement of a polyethylene ring for up to 48 h in 30 rats. Sham and normal groups were also studied (n = 12). Five 6 cm-long intestinal segments proximal to the obstruction site were used for histological, morphometric and mechanical analysis at the designated times. Morphomechanical changes were huge but only subtle changes were observed between the 5 segments during the obstruction period. Due to dilation, the serosal length and mucosal length increased continuously from 6 to 48 h (p < 0.001). The wall area increased at 24 h and beyond (p < 0.001), demonstrating tissue growth. The opening and bending angle decreased to minimum values at 24 h where after the opening angle increased and the bending angle returned to pre-obstruction levels. For the residual stretch ratios and the position of the neutral axis the turning point was found after 24 h. Histologically, the thickness and area of most wall layers were quite stable for the first 12 h but with an increase at the 24 h time point that continued to the 48 h time point. The most pronounced change was found for the circumferential muscle layer (p < 0.05). Analysis of picrosirius red stained slides showed that submucosal type 3 collagen fraction increased significantly (p < 0.001), whereas the fraction of type 1 collagen decreased (p < 0.001). In conclusion, pronounced time-dependent morphomechanical remodeling was found. The obstructed intestine went from dilation remodeling to growth remodeling during the interval 12–24 h after creating the obstruction.
      PubDate: 2018-05-01
      DOI: 10.1007/s10439-018-1992-z
      Issue No: Vol. 46, No. 5 (2018)
  • A Diaper Pad for Diaper-Based Urine Collection and Colorimetric Screening
           of Urinary Biomarkers
    • Authors: Haakon Karlsen; Tao Dong; Zhenhe Suo
      Pages: 717 - 725
      Abstract: The high prevalence of urinary tract infection in aging adults is a challenging aspect of geriatric care. Incontinence and cognitive/functional impairment make collection of urine samples difficult and often require either catheterization for sample collection, which is a risk factor for infections, or more lenient criteria for initiating antibiotic treatment. We report the development of a diaper inlay with absorbent materials, superabsorbent polymer-based valve and chemical reaction pads for rapid screening of urinary tract infection of incontinent diaper-wearing elderly receivers of home care services. The developed diaper inlay was capable of collecting, isolating, analyzing samples and retaining results > 8 h. The diaper inlay can therefore be compatible with the diaper changing routines of nurses in home care services, without requiring much time or effort. A nurse can insert a diaper inlay in a diaper and the results can be recorded during a later diaper change. Although the research focuses on tools for home care services, the nursing home sector has similar problems and may benefit from technological development for rapid screening to avoid unnecessary catheterization and overuse of antibiotics.
      PubDate: 2018-05-01
      DOI: 10.1007/s10439-018-1996-8
      Issue No: Vol. 46, No. 5 (2018)
  • UROKIN: A Software to Enhance Our Understanding of Urogenital Motion
    • Authors: Catriona S. Czyrnyj; Michel R. Labrosse; Ryan B. Graham; Linda McLean
      Pages: 726 - 735
      Abstract: Transperineal ultrasound (TPUS) allows for objective quantification of mid-sagittal urogenital mechanics, yet current practice omits dynamic motion information in favor of analyzing only a rest and a peak motion frame. This work details the development of UROKIN, a semi-automated software which calculates kinematic curves of urogenital landmark motion. A proof of concept analysis, performed using UROKIN on TPUS video recorded from 20 women with and 10 women without stress urinary incontinence (SUI) performing maximum voluntary contraction of the pelvic floor muscles. The anorectal angle and bladder neck were tracked while the motion of the pubic symphysis was used to compensate for the error incurred by TPUS probe motion during imaging. Kinematic curves of landmark motion were generated for each video and curves were smoothed, time normalized, and averaged within groups. Kinematic data yielded by the UROKIN software showed statistically significant differences between women with and without SUI in terms of magnitude and timing characteristics of the kinematic curves depicting landmark motion. Results provide insight into the ways in which UROKIN may be useful to study differences in pelvic floor muscle contraction mechanics between women with and without SUI and other pelvic floor disorders. The UROKIN software improves on methods described in the literature and provides unique capacity to further our understanding of urogenital biomechanics.
      PubDate: 2018-05-01
      DOI: 10.1007/s10439-018-1989-7
      Issue No: Vol. 46, No. 5 (2018)
  • Human Brain Modeling with Its Anatomical Structure and Realistic Material
           Properties for Brain Injury Prediction
    • Authors: Noritoshi Atsumi; Yuko Nakahira; Eiichi Tanaka; Masami Iwamoto
      Pages: 736 - 748
      Abstract: Impairments of executive brain function after traumatic brain injury (TBI) due to head impacts in traffic accidents need to be obviated. Finite element (FE) analyses with a human brain model facilitate understanding of the TBI mechanisms. However, conventional brain FE models do not suitably describe the anatomical structure in the deep brain, which is a critical region for executive brain function, and the material properties of brain parenchyma. In this study, for better TBI prediction, a novel brain FE model with anatomical structure in the deep brain was developed. The developed model comprises a constitutive model of brain parenchyma considering anisotropy and strain rate dependency. Validation was performed against postmortem human subject test data associated with brain deformation during head impact. Brain injury analyses were performed using head acceleration curves obtained from reconstruction analysis of rear-end collision with a human whole-body FE model. The difference in structure was found to affect the regions of strain concentration, while the difference in material model contributed to the peak strain value. The injury prediction result by the proposed model was consistent with the characteristics in the neuroimaging data of TBI patients due to traffic accidents.
      PubDate: 2018-05-01
      DOI: 10.1007/s10439-018-1988-8
      Issue No: Vol. 46, No. 5 (2018)
  • Investigating the Longitudinal Effect of Ovariectomy on Bone Properties
           Using a Novel Spatiotemporal Approach
    • Authors: Yongtao Lu; Yue Liu; Chengwei Wu; Junyan Li
      Pages: 749 - 761
      Abstract: Osteoporosis is the most common bone disease. However, the mechanism of osteoporosis-induced alterations in bone is still unclear. The aim of this study was to investigate the effects of osteoporosis on the structural, densitometric and mechanical properties of the whole tibia using in vivo μCT imaging, spatiotemporal analysis and finite element modeling. Twelve C57Bl/6 female mice were adopted. At 14 weeks of age, half of the mice were ovariectomized (OVX), and the other half were SHAM-operated. The whole right tibia was scanned using an in vivo μCT imaging system at 14, 16, 17, 18, 19, 20, 21 and 22 weeks. The image datasets were registered in order to precisely quantify the bone properties. The results showed that OVX led to a significant increase in the endosteal area across the whole tibia 4 weeks after OVX intervention but did not have a significant influence on the periosteal area. Additionally, the bone volume and mineral content significantly decreased only in the proximal regions, but these decreases did not have a significant influence on the stiffness and failure load of the tibia. This study demonstrated the application of a novel spatiotemporal approach in the comprehensive analysis of bone adaptations in the spatiotemporal space.
      PubDate: 2018-05-01
      DOI: 10.1007/s10439-018-1994-x
      Issue No: Vol. 46, No. 5 (2018)
  • Effects of Hollow Fiber Membrane Oscillation on an Artificial Lung
    • Authors: Ryan A. Orizondo; Guy Gino; Garret Sultzbach; Shalv P. Madhani; Brian J. Frankowski; William J. Federspiel
      Pages: 762 - 771
      Abstract: Gas transfer through hollow fiber membranes (HFMs) can be increased via fiber oscillation. Prior work, however, does not directly translate to present-day, full-scale artificial lungs. This in vitro study characterized the effects of HFM oscillations on oxygenation and hemolysis for a pediatric-sized HFM bundle. Effects of oscillation stroke length (2–10 mm) and frequency (1–25 Hz) on oxygen transfer were measured according to established standards. The normalized index of hemolysis was measured for select conditions. All measurements were performed at a 2.5 L min−1 blood flow rate. A lumped parameter model was used to predict oscillation-induced blood flow and elucidate the effects of system parameters on oxygenation. Oxygen transfer increased during oscillations, reaching a maximum oxygenation efficiency of 510 mL min−1 m−2 (97% enhancement relative to no oscillation). Enhancement magnitudes matched well with model-predicted trends and were dependent on stroke length, frequency, and physical system parameters. A 40% oxygenation enhancement was achieved without significant hemolysis increase. At a constant enhancement magnitude, a larger oscillation frequency resulted in increased hemolysis. In conclusion, HFM oscillation is a feasible approach to increasing artificial lung gas transfer efficiency. The optimal design for maximizing efficiency at small fiber displacements should minimize bundle resistance and housing compliance.
      PubDate: 2018-05-01
      DOI: 10.1007/s10439-018-1995-9
      Issue No: Vol. 46, No. 5 (2018)
  • Real-Time Closed Loop Diastolic Interval Control Prevents Cardiac
           Alternans in Isolated Whole Rabbit Hearts
    • Authors: Kanchan Kulkarni; Steven W. Lee; Ryan Kluck; Elena G. Tolkacheva
      Pages: 555 - 566
      Abstract: Cardiac alternans, a beat-to-beat alternation in action potential duration (APD), can lead to fatal arrhythmias. During periodic pacing, changes in diastolic interval (DI) depend on subsequent changes in APD, thus enhancing cardiac instabilities through a ‘feedback’ mechanism. Recently, an anti-arrhythmic Constant DI pacing protocol was proposed and shown to be effective in suppressing alternans in 0D and 1D in silico studies. However, previous experimental validation of Constant DI pacing in the heart has been unsuccessful due to the spatio-temporal complexity of 2D cardiac tissue and the technical challenges in its real-time implementation. Here, we developed a novel closed loop system to detect T-waves from real-time ECG data, enabling successful implementation of Constant DI pacing protocol, and performed high-resolution optical mapping experiments on isolated whole rabbit hearts to validate its anti-arrhythmic effects. The results were compared with: (1) Periodic pacing (feedback inherent) and (2) pacing with heart rate variability (HRV) (feedback modulation) introduced by using either Gaussian or Physiological patterns. We observed that Constant DI pacing significantly suppressed alternans in the heart, while maintaining APD spatial dispersion and flattening the slope of the APD restitution curve, compared to traditional Periodic pacing. In addition, introduction of HRV in Periodic pacing failed to prevent cardiac alternans, and was arrhythmogenic.
      PubDate: 2018-04-01
      DOI: 10.1007/s10439-018-1981-2
      Issue No: Vol. 46, No. 4 (2018)
  • Computational Fluid Dynamics Modeling of the Burr Orbital Motion in
           Rotational Atherectomy with Particle Image Velocimetry Validation
    • Authors: Yihao Zheng; Yang Liu; John J. Pitre; Joseph L. Bull; Hitinder S. Gurm; Albert J. Shih
      Pages: 567 - 578
      Abstract: Rotational atherectomy (RA) uses a high-speed rotating burr introduced via a catheter through the artery to remove hardened atherosclerotic plaque. Current clinical RA technique lacks consensus on burr size and rotational speed. The rotating burr orbits inside the artery due to the fluid force of the blood. Different from a common RA technique of upsizing burrs for larger luminal gain, a small burr can orbit to treat a large lumen. A 3D computational fluid dynamics (CFD) model was developed to simulate the burr motion and study the fluid flow and force in RA. A particle image velocimetry experiment was conducted to measure and validate the flow field including the radial and axial velocities and a pair of counter-rotating vortices near the burr equator in CFD. The hydraulic force on the burr and the contact force between the burr and the arterial wall were estimated by CFD. The contact force can be reduced by using smaller burr and lower rotational speed. Utilizing the small burr orbital motion has the potential to be an improved RA technique.
      PubDate: 2018-04-01
      DOI: 10.1007/s10439-018-1984-z
      Issue No: Vol. 46, No. 4 (2018)
  • VascuTrainer: A Mobile and Disposable Bioreactor System for the
           Conditioning of Tissue-Engineered Vascular Grafts
    • Authors: Frederic Wolf; Diana M. Rojas González; Ulrich Steinseifer; Markus Obdenbusch; Werner Herfs; Christian Brecher; Stefan Jockenhoevel; Petra Mela; Thomas Schmitz-Rode
      Pages: 616 - 626
      Abstract: In vitro tissue engineering of vascular grafts requires dynamic conditioning in a bioreactor system for in vitro tissue maturation and remodeling to receive a mechanically adequate and hemocompatible implant. The goal of the current work was to develop a bioreactor system for the conditioning of vascular grafts which is (i) able to create a wide range of flow, pressure and frequency conditions, including physiological ones; (ii) compact and easy to assemble; (iii) transportable; (iv) disposable. The system is driven by a small centrifugal pump controlled via a custom-made control unit, which can also be operated on batteries to allow for autonomous transportation. To show the potential of the newly developed bioreactor system small-caliber vascular composite grafts (n = 5, internal diameter = 3 mm, length = 12.5 cm) were fabricated using a fibrin scaffold embedding human umbilical artery smooth muscle cells and a polyvinylidene fluoride warp-knitted macroporous mesh. Subsequently, the vascular grafts were endothelialized and mounted in the bioreactor system for conditioning. The conditioning parameters remained within the predefined range over the complete conditioning period and during operation on batteries as tested for up to 25 h. Fabrication and pre-conditioning under arterial pressure and shear stress conditions resulted in robust and hemocompatible tissue-engineered vascular grafts. Analysis of immunohistochemical stainings against extracellular matrix and cell-specific proteins revealed collagen I and collagen III deposition. The luminal surface was confluently covered with endothelial cells. The developed bioreactor system showed cytocompatibility and pH, pO2, pCO2, glucose and lactate stayed constant. Sterility was maintained during the complete fabrication process of the vascular grafts. The potential of a versatile and mobile system and its functionality by conditioning tissue-engineered vascular grafts under physiological pressure and flow conditions could be demonstrated.
      PubDate: 2018-04-01
      DOI: 10.1007/s10439-018-1977-y
      Issue No: Vol. 46, No. 4 (2018)
  • Correction to: Mesenchymal Stem Cell Deformability and Implications for
           Microvascular Sequestration
    • Authors: Herbert H. Lipowsky; Daniel T. Bowers; Brittany L. Banik; Justin L. Brown
      Pages: 655 - 655
      Abstract: This article was updated to correct the spelling of author Brittany L. Banik’s name.
      PubDate: 2018-04-01
      DOI: 10.1007/s10439-018-1991-0
      Issue No: Vol. 46, No. 4 (2018)
  • Inter-subject FDG PET Brain Networks Exhibit Multi-scale Community
           Structure with Different Normalization Techniques
    • Authors: Megan M. Sperry; Sonia Kartha; Eric J. Granquist; Beth A. Winkelstein
      Abstract: Inter-subject networks are used to model correlations between brain regions and are particularly useful for metabolic imaging techniques, like 18F-2-deoxy-2-(18F)fluoro-d-glucose (FDG) positron emission tomography (PET). Since FDG PET typically produces a single image, correlations cannot be calculated over time. Little focus has been placed on the basic properties of inter-subject networks and if they are affected by group size and image normalization. FDG PET images were acquired from rats (n = 18), normalized by whole brain, visual cortex, or cerebellar FDG uptake, and used to construct correlation matrices. Group size effects on network stability were investigated by systematically adding rats and evaluating local network connectivity (node strength and clustering coefficient). Modularity and community structure were also evaluated in the differently normalized networks to assess meso-scale network relationships. Local network properties are stable regardless of normalization region for groups of at least 10. Whole brain-normalized networks are more modular than visual cortex- or cerebellum-normalized network (p < 0.00001); however, community structure is similar at network resolutions where modularity differs most between brain and randomized networks. Hierarchical analysis reveals consistent modules at different scales and clustering of spatially-proximate brain regions. Findings suggest inter-subject FDG PET networks are stable for reasonable group sizes and exhibit multi-scale modularity.
      PubDate: 2018-04-11
      DOI: 10.1007/s10439-018-2022-x
  • Experimental Verification of the Elastic Formula for the Aspirated Length
           of a Single Cell Considering the Size and Compressibility of Cell During
           Micropipette Aspiration
    • Authors: YongSheng Li; Jing Chen; LiLi Wang; Yuan Guo; JiLing Feng; WeiYi Chen
      Abstract: In this study, an aspiration system for elastic spheres was developed to verify the approximate elastic formula for the aspirated length of a single solid-like cell undergoing micropipette aspiration (MPA), which was obtained in our previous study by theoretical analysis and numerical simulation. Using this system, foam silicone rubber spheres with different diameters and mechanical properties were aspirated in a manner similar to the MPA of single cells. Comparisons between the approximate elastic formula and aspiration experiments of spheres indicated that the predictions of the formula agreed with the experimental results. Additionally, combined with the MPA data of rabbit chondrocytes, differences in terms of the elastic parameters derived from the half-space model, incompressible sphere model, and compressible sphere model were explored. The results demonstrated that the parameter ξ (ξ = R/a, where R is the radius of the cell and a is the inner radius of the micropipette) and Poisson’s ratio significantly influenced the determination of the elastic modulus and bulk modulus of the cell. This work developed for the first time an aspiration system of elastic spheres to study the elastic responses of the MPA of a single cell and provided new evidence supporting the use of the approximate elastic formula to determine cellular elastic parameters from the MPA data.
      PubDate: 2018-04-10
      DOI: 10.1007/s10439-018-2023-9
  • Hyperelastic Mechanical Properties of Ex Vivo Normal and Intrauterine
           Growth Restricted Placenta
    • Authors: Shier Nee Saw; Jess Yi Ru Low; May Han Huang Ong; Yu Wei Poh; Citra Nurfarah Zaini Mattar; Arijit Biswas; Choon Hwai Yap
      Abstract: Intrauterine Growth Restriction (IUGR) is a serious and prevalent pregnancy complication that is due to placental insufficiency and IUGR babies suffer significantly higher risks of mortality and morbidity. Current detection rate for IUGR is generally poor and thus an alternative diagnostic tool is needed to improve the IUGR detection. Elastography, a non-invasive method that measures the tissue stiffness, has been proposed as one such technique. However, to date, we have limited information on the mechanical properties of IUGR placenta. In this study, we investigated the mechanical properties of normal and IUGR placentae and prescribed a suitable hyperelastic model to describe their mechanical behaviors. A total of 46 normal and 43 IUGR placenta samples were investigated. Results showed that placenta samples were isotropic, but had a high spatial variability of stiffness. The samples also had significant viscoelasticity. IUGR placenta was observed to be slightly stiffer than normal placenta but the difference was significant only at compression rate of 0.25 Hz and with 20% compression depth. Three simple hyperelastic models—Yeoh, Ogden and Fung models, were found to be able to fit the experimentally measured mechanical behaviors, and Fung model performed slightly better. These results may be useful for optimizing placenta elastography for the detection of IUGR.
      PubDate: 2018-04-06
      DOI: 10.1007/s10439-018-2019-5
  • A Semi-passive Planar Manipulandum for Upper-Extremity Rehabilitation
    • Authors: Chih-Kang Chang; Edward P. Washabaugh; Andrew Gwozdziowski; C. David Remy; Chandramouli Krishnan
      Abstract: Robotic rehabilitation is a promising approach to treat individuals with neurological or orthopedic disorders. However, despite significant advancements in the field of rehabilitation robotics, this technology has found limited traction in clinical practice. A key reason for this issue is that most robots are expensive, bulky, and not scalable for in-home rehabilitation. Here, we introduce a semi-passive rehabilitation robot (SepaRRo) that uses controllable passive actuators (i.e., brakes) to provide controllable resistances at the end-effector over a large workspace in a manner that is cost-effective and safe for in-home use. We also validated the device through theoretical analyses, hardware experiments, and human subject experiments. We found that by including kinematic redundancies in the robot’s linkages, the device was able to provide controllable resistances to purely resist the movement of the end-effector, or to gently steer (i.e., perturb) its motion away from the intended path. When testing these capabilities on human subjects, we found that many of the upper-extremity muscles could be selectively targeted based on the forcefield prescribed to the user. These results indicate that SepaRRo could serve as a low-cost therapeutic tool for upper-extremity rehabilitation; however, further testing is required to evaluate its therapeutic benefits in patient population.
      PubDate: 2018-04-06
      DOI: 10.1007/s10439-018-2020-z
  • A Novel High-Resolution Method for the Respiration Rate and Breathing
           Waveforms Remote Monitoring
    • Abstract: A search for robust noninvasive methods permitting to discern the respiration subtle peculiarities in mammals is a topical issue. A novel approach called “sorption-enhanced infrared thermography” (SEIRT), helping to solve this problem, is described. Its benefits spring from the integration of the infrared thermography (IRT) and chemical physics (phase transition heat release/absorption) within a single method. The SEIRT opportunities were verified in the investigation of 42 humans, 49 rats and 4 minipigs whose breathing waveforms were revealed to the last detail. It is shown that the SEIRT-obtained breathing-conditioned temperature response may exceed 10 °C (!) even in small animals (rats) and that the SEIRT sensitivity is 4.5–250 times higher than that of the matched IRT-based techniques. The new method is validated by a comparison with that based on thorax breathing movement (TBM). It is shown that the SEIRT-determined breaths have a close correlation with those determined via TBM (r = + 1.000, p ≪ 0.05); this is also true for breathing intervals (r = + 0.9772, p ≪ 0.05). SEIRT opens up the way to a high-resolution noncontact quantitative evaluation of respiration rate and breathing waveforms in both humans and animals. It may become a cutting-edge technique in diagnostic medicine and biomedical research.
      PubDate: 2018-04-04
      DOI: 10.1007/s10439-018-2018-6
  • Performance Assessment of a Radiofrequency Powered Guidewire for Crossing
           Peripheral Arterial Occlusions Based on Lesion Morphology
    • Authors: Mohammad A. Tavallaei; James J. Zhou; Trisha L. Roy; Graham A. Wright
      Abstract: Endovascular wires and devices for peripheral arterial disease therapy have evolved greatly, yet failure rates of these procedures remain high. Information on lesion composition may inform device selection to improve the success rates of these procedures. This paper, presents an approach for informed guidewire selection. The objective of this study is to quantitatively assess the performance of a radiofrequency powered guidewire in the crossing of various morphology types of peripheral chronic total occlusions. Samples taken from amputated patient limbs are characterized by magnetic resonance imaging. Using a customized catheter test station, the performance of a radiofrequency powered guidewire in puncturing these lesions is compared to a conventional guidewire, and to itself when not powered. The analysis includes quantitative and statistical comparisons of the puncture forces experienced by the different guidewires in “hard” vs. “soft” lesions as well as qualitative assessment of deflections, buckling and puncture success of the wires. Results indicate that the use of radiofrequency ablation significantly reduces the required puncture force, reduced events of buckling and deflection, and resulted in a significantly higher puncture success rate.
      PubDate: 2018-04-03
      DOI: 10.1007/s10439-018-2021-y
  • Spheroid Culture System Confers Differentiated Transcriptome Profile and
           Functional Advantage to 3T3-L1 Adipocytes
    • Authors: Paul A. Turner; Michael R. Garrett; Sean P. Didion; Amol V. Janorkar
      Abstract: This study highlights functional differences between 2-D monolayer and 3-D spheroid 3T3-L1 adipocyte culture models and explores the underlying genomic mechanisms responsible for the different phenotypes present. The spheroids showed higher triglyceride accumulation than the monolayer culture and further increase with larger spheroid size. Whole transcriptome analysis indicated significant differential expression of genes related to adipogenesis, including adipocytokine signaling, fatty acid metabolism, and PPAR-γ signaling. Spheroids also showed downregulation of matrix metalloproteinases (MMPs), integrin, actin-cytoskeleton associated genes, and Rho/GTPase3 expression relative to 2-D monolayer, indicating suppression of the Rho-ROCK pathway and thereby promoting adipogenic differentiation. When exposed to linoleic acid (500 μM) and TNF-α (125 ng/mL) to promote chronic adiposity, linoleic acid treatment resulted in increased intracellular triglycerides and subsequent TNF-α treatment resulted in significantly altered adipocytokine signaling, fatty acid metabolism, and PPAR signaling, in addition to upregulation of multiple MMPs in spheroids vs. monolayer. Overall, 3-D spheroids showed enhanced adipogenic phenotype as indicated by triglyceride synthesis and transcriptome changes while retaining sensitivity to a pro-inflammatory stimulus. The 3-D spheroid culture thus may provide a simple, convenient, and sensitive in vitro model to study adipocyte response to metabolic stresses relevant to clinical pathologies.
      PubDate: 2018-03-02
      DOI: 10.1007/s10439-018-1993-y
  • Solid Stress Facilitates Fibroblasts Activation to Promote Pancreatic
           Cancer Cell Migration
    • Authors: Maria Kalli; Panagiotis Papageorgis; Vasiliki Gkretsi; Triantafyllos Stylianopoulos
      Abstract: Pancreatic fibroblasts are continuously gaining ground as an important component of tumor microenvironment that dynamically interact with cancer cells to promote tumor progression. In addition, these tumor-infiltrated fibroblasts can acquire an activated phenotype and produce excessive amounts of extracellular matrix creating a highly dense stroma, a situation known as desmoplasia. Desmoplasia, along with the uncontrolled proliferation of cancer cells, leads to the development of compressive forces within the tumor, generating the so-called solid stress. Solid stress is previously shown to affect cancer cell proliferation and migration, however there is no pertinent study taking into account the effects of solid stress on fibroblasts and whether these effects contribute to tumor progression. In this work, we applied a defined compressive stress on pancreatic fibroblasts, similar in magnitude to that experienced by cells in native pancreatic tumors. Our results suggest that solid stress stimulates fibroblasts activation and strongly upregulates Growth Differentiation Factor-15 (GDF15) expression. Moreover, co-culture of compression-induced activated fibroblasts with pancreatic cancer cells significantly promotes cancer cell migration, which is inhibited by shRNA-mediated silencing of GDF15 in fibroblasts. Conclusively, our findings highlight the involvement of biophysical factors, such as solid stress, in tumor progression and malignancy revealing a novel role for GDF15.
      PubDate: 2018-02-22
      DOI: 10.1007/s10439-018-1997-7
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