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  Subjects -> BIOLOGY (Total: 3086 journals)
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BIOLOGY (1462 journals)                  1 2 3 4 5 6 7 8 | Last

Showing 1 - 200 of 1720 Journals sorted alphabetically
AAPS Journal     Hybrid Journal   (Followers: 21)
Achievements in the Life Sciences     Open Access   (Followers: 5)
ACS Synthetic Biology     Full-text available via subscription   (Followers: 23)
Acta Biologica Colombiana     Open Access   (Followers: 7)
Acta Biologica Hungarica     Full-text available via subscription   (Followers: 4)
Acta Biologica Sibirica     Open Access  
Acta Biomaterialia     Hybrid Journal   (Followers: 27)
Acta Biotheoretica     Hybrid Journal   (Followers: 4)
Acta Chiropterologica     Full-text available via subscription   (Followers: 6)
acta ethologica     Hybrid Journal   (Followers: 4)
Acta Limnologica Brasiliensia     Open Access   (Followers: 3)
Acta Médica Costarricense     Open Access   (Followers: 2)
Acta Musei Silesiae, Scientiae Naturales : The Journal of Silesian Museum in Opava     Open Access  
Acta Neurobiologiae Experimentalis     Open Access  
Acta Parasitologica     Hybrid Journal   (Followers: 10)
Acta Scientiarum. Biological Sciences     Open Access   (Followers: 2)
Acta Scientifica Naturalis     Open Access   (Followers: 2)
Actualidades Biológicas     Open Access   (Followers: 1)
Advanced Health Care Technologies     Open Access   (Followers: 4)
Advanced Studies in Biology     Open Access  
Advances in Antiviral Drug Design     Full-text available via subscription   (Followers: 2)
Advances in Bioinformatics     Open Access   (Followers: 17)
Advances in Biological Regulation     Hybrid Journal   (Followers: 4)
Advances in Biosensors and Bioelectronics     Open Access   (Followers: 7)
Advances in Cell Biology     Open Access   (Followers: 24)
Advances in Cellular and Molecular Biology of Membranes and Organelles     Full-text available via subscription   (Followers: 12)
Advances in Developmental Biology     Full-text available via subscription   (Followers: 10)
Advances in DNA Sequence-Specific Agents     Full-text available via subscription   (Followers: 5)
Advances in Ecological Research     Full-text available via subscription   (Followers: 42)
Advances in Environmental Sciences - International Journal of the Bioflux Society     Open Access   (Followers: 18)
Advances in Enzyme Research     Open Access   (Followers: 9)
Advances in Experimental Biology     Full-text available via subscription   (Followers: 6)
Advances in Genome Biology     Full-text available via subscription   (Followers: 7)
Advances in High Energy Physics     Open Access   (Followers: 18)
Advances in Human Biology     Open Access   (Followers: 2)
Advances in Life Science and Technology     Open Access   (Followers: 14)
Advances in Life Sciences     Open Access   (Followers: 6)
Advances in Marine Biology     Full-text available via subscription   (Followers: 15)
Advances in Molecular and Cell Biology     Full-text available via subscription   (Followers: 21)
Advances in Organ Biology     Full-text available via subscription   (Followers: 1)
Advances in Planar Lipid Bilayers and Liposomes     Full-text available via subscription   (Followers: 3)
Advances in Regenerative Biology     Open Access   (Followers: 1)
Advances in Space Biology and Medicine     Full-text available via subscription   (Followers: 5)
Advances in Structural Biology     Full-text available via subscription   (Followers: 5)
Advances in Virus Research     Full-text available via subscription   (Followers: 5)
African Journal of Range & Forage Science     Hybrid Journal   (Followers: 6)
AFRREV STECH : An International Journal of Science and Technology     Open Access   (Followers: 1)
Ageing Research Reviews     Hybrid Journal   (Followers: 9)
Aging Cell     Open Access   (Followers: 11)
Agrokémia és Talajtan     Full-text available via subscription   (Followers: 2)
Agrokreatif Jurnal Ilmiah Pengabdian kepada Masyarakat     Open Access  
AJP Cell Physiology     Full-text available via subscription   (Followers: 14)
AJP Endocrinology and Metabolism     Full-text available via subscription   (Followers: 23)
AJP Lung Cellular and Molecular Physiology     Full-text available via subscription   (Followers: 3)
Al-Kauniyah : Jurnal Biologi     Open Access  
Alasbimn Journal     Open Access   (Followers: 1)
AMB Express     Open Access   (Followers: 1)
Ambix     Hybrid Journal   (Followers: 3)
American Biology Teacher     Full-text available via subscription   (Followers: 14)
American Fern Journal     Full-text available via subscription   (Followers: 1)
American Journal of Agricultural and Biological Sciences     Open Access   (Followers: 8)
American Journal of Bioethics     Hybrid Journal   (Followers: 10)
American Journal of Human Biology     Hybrid Journal   (Followers: 13)
American Journal of Medical and Biological Research     Open Access   (Followers: 8)
American Journal of Plant Sciences     Open Access   (Followers: 18)
American Journal of Primatology     Hybrid Journal   (Followers: 14)
American Malacological Bulletin     Full-text available via subscription   (Followers: 3)
American Naturalist     Full-text available via subscription   (Followers: 70)
Amphibia-Reptilia     Hybrid Journal   (Followers: 6)
Anaerobe     Hybrid Journal   (Followers: 4)
Analytical Methods     Full-text available via subscription   (Followers: 10)
Anatomical Science International     Hybrid Journal   (Followers: 2)
Animal Cells and Systems     Hybrid Journal   (Followers: 4)
Annales de Limnologie - International Journal of Limnology     Hybrid Journal   (Followers: 1)
Annales françaises d'Oto-rhino-laryngologie et de Pathologie Cervico-faciale     Full-text available via subscription   (Followers: 3)
Annales Henri Poincaré     Hybrid Journal   (Followers: 3)
Annales UMCS, Biologia     Open Access   (Followers: 1)
Annals of Applied Biology     Hybrid Journal   (Followers: 7)
Annals of Biomedical Engineering     Hybrid Journal   (Followers: 18)
Annals of Human Biology     Hybrid Journal   (Followers: 5)
Annual Review of Biomedical Engineering     Full-text available via subscription   (Followers: 15)
Annual Review of Biophysics     Full-text available via subscription   (Followers: 23)
Annual Review of Cancer Biology     Full-text available via subscription   (Followers: 1)
Annual Review of Cell and Developmental Biology     Full-text available via subscription   (Followers: 37)
Annual Review of Food Science and Technology     Full-text available via subscription   (Followers: 13)
Annual Review of Genomics and Human Genetics     Full-text available via subscription   (Followers: 23)
Annual Review of Phytopathology     Full-text available via subscription   (Followers: 10)
Anthropological Review     Open Access   (Followers: 23)
Anti-Infective Agents     Hybrid Journal   (Followers: 3)
Antibiotics     Open Access   (Followers: 9)
Antioxidants     Open Access   (Followers: 4)
Antioxidants & Redox Signaling     Hybrid Journal   (Followers: 8)
Antonie van Leeuwenhoek     Hybrid Journal   (Followers: 5)
Anzeiger für Schädlingskunde     Hybrid Journal   (Followers: 1)
Apidologie     Hybrid Journal   (Followers: 4)
Apmis     Hybrid Journal   (Followers: 1)
APOPTOSIS     Hybrid Journal   (Followers: 8)
Applied Bionics and Biomechanics     Open Access   (Followers: 8)
Applied Vegetation Science     Full-text available via subscription   (Followers: 10)
Aquaculture Environment Interactions     Open Access   (Followers: 2)
Aquaculture International     Hybrid Journal   (Followers: 22)
Aquaculture Reports     Open Access   (Followers: 3)
Aquaculture, Aquarium, Conservation & Legislation - International Journal of the Bioflux Society     Open Access   (Followers: 6)
Aquatic Biology     Open Access   (Followers: 5)
Aquatic Ecology     Hybrid Journal   (Followers: 32)
Aquatic Ecosystem Health & Management     Hybrid Journal   (Followers: 14)
Aquatic Science and Technology     Open Access   (Followers: 3)
Aquatic Toxicology     Hybrid Journal   (Followers: 21)
Archaea     Open Access   (Followers: 3)
Archiv für Molluskenkunde: International Journal of Malacology     Full-text available via subscription   (Followers: 3)
Archives of Biological Sciences     Open Access  
Archives of Biomedical Sciences     Open Access   (Followers: 7)
Archives of Microbiology     Hybrid Journal   (Followers: 8)
Archives of Natural History     Hybrid Journal   (Followers: 6)
Archives of Oral Biology     Hybrid Journal   (Followers: 2)
Archives of Virology     Hybrid Journal   (Followers: 5)
Archivum Immunologiae et Therapiae Experimentalis     Hybrid Journal   (Followers: 2)
Arid Ecosystems     Hybrid Journal   (Followers: 2)
Arquivos do Instituto Biológico     Open Access   (Followers: 1)
Arquivos do Museu Dinâmico Interdisciplinar     Open Access  
Arthropod Structure & Development     Hybrid Journal   (Followers: 2)
Arthropods     Open Access   (Followers: 1)
Artificial DNA: PNA & XNA     Hybrid Journal   (Followers: 3)
Artificial Photosynthesis     Open Access   (Followers: 1)
Asian Bioethics Review     Full-text available via subscription   (Followers: 3)
Asian Journal of Biodiversity     Open Access   (Followers: 4)
Asian Journal of Biological Sciences     Open Access   (Followers: 3)
Asian Journal of Cell Biology     Open Access   (Followers: 5)
Asian Journal of Developmental Biology     Open Access   (Followers: 2)
Asian Journal of Medical and Biological Research     Open Access   (Followers: 3)
Asian Journal of Nematology     Open Access   (Followers: 4)
Asian Journal of Poultry Science     Open Access   (Followers: 3)
Australian Life Scientist     Full-text available via subscription   (Followers: 2)
Australian Mammalogy     Hybrid Journal   (Followers: 6)
Autophagy     Hybrid Journal   (Followers: 2)
Avian Biology Research     Full-text available via subscription   (Followers: 4)
Avian Conservation and Ecology     Open Access   (Followers: 11)
Bacteriology Journal     Open Access   (Followers: 1)
Bacteriophage     Full-text available via subscription   (Followers: 3)
Bangladesh Journal of Bioethics     Open Access  
Bangladesh Journal of Plant Taxonomy     Open Access  
Bangladesh Journal of Scientific Research     Open Access   (Followers: 1)
Berita Biologi     Open Access   (Followers: 1)
Between the Species     Open Access   (Followers: 1)
Bio Tribune Magazine     Hybrid Journal  
BIO Web of Conferences     Open Access  
BIO-Complexity     Open Access  
Bio-Grafía. Escritos sobre la Biología y su enseñanza     Open Access  
Bioanalytical Reviews     Hybrid Journal   (Followers: 2)
Biocatalysis and Biotransformation     Hybrid Journal   (Followers: 6)
Biochemistry and Cell Biology     Hybrid Journal   (Followers: 15)
Biochimie     Hybrid Journal   (Followers: 7)
BioControl     Hybrid Journal   (Followers: 5)
Biocontrol Science and Technology     Hybrid Journal   (Followers: 5)
Biodemography and Social Biology     Hybrid Journal  
BioDiscovery     Open Access   (Followers: 2)
Biodiversitas : Journal of Biological Diversity     Open Access  
Biodiversity : Research and Conservation     Open Access   (Followers: 26)
Biodiversity and Natural History     Open Access   (Followers: 6)
Biodiversity Data Journal     Open Access   (Followers: 3)
Biodiversity Informatics     Open Access   (Followers: 1)
Biodiversity Information Science and Standards     Open Access  
Bioedukasi : Jurnal Pendidikan Biologi FKIP UM Metro     Open Access  
Bioeksperimen : Jurnal Penelitian Biologi     Open Access  
Bioelectrochemistry     Hybrid Journal   (Followers: 2)
Bioelectromagnetics     Hybrid Journal   (Followers: 1)
Bioenergy Research     Hybrid Journal   (Followers: 2)
Bioengineering and Bioscience     Open Access   (Followers: 1)
BioEssays     Hybrid Journal   (Followers: 10)
Bioethics     Hybrid Journal   (Followers: 14)
BioéthiqueOnline     Open Access  
Biofabrication     Hybrid Journal   (Followers: 5)
Biofilms     Full-text available via subscription   (Followers: 1)
Biogeosciences (BG)     Open Access   (Followers: 10)
Biogeosciences Discussions (BGD)     Open Access   (Followers: 2)
Bioinformatics     Hybrid Journal   (Followers: 285)
Bioinformatics and Biology Insights     Open Access   (Followers: 11)
Bioinspiration & Biomimetics     Hybrid Journal   (Followers: 7)
Biointerphases     Open Access   (Followers: 1)
Biojournal of Science and Technology     Open Access  
Biologia     Hybrid Journal  
Biologia on-line : Revista de divulgació de la Facultat de Biologia     Open Access  
Biological Bulletin     Partially Free   (Followers: 6)
Biological Control     Hybrid Journal   (Followers: 4)
Biological Invasions     Hybrid Journal   (Followers: 18)
Biological Journal of the Linnean Society     Hybrid Journal   (Followers: 18)
Biological Letters     Open Access   (Followers: 5)
Biological Procedures Online     Open Access  
Biological Psychiatry     Hybrid Journal   (Followers: 45)
Biological Psychology     Hybrid Journal   (Followers: 7)
Biological Research     Open Access  
Biological Rhythm Research     Hybrid Journal   (Followers: 2)
Biological Theory     Hybrid Journal   (Followers: 2)
Biological Trace Element Research     Hybrid Journal  
Biologicals     Full-text available via subscription   (Followers: 9)
Biologics: Targets & Therapy     Open Access   (Followers: 1)
Biologie Aujourd'hui     Full-text available via subscription  
Biologie in Unserer Zeit (Biuz)     Hybrid Journal   (Followers: 40)
Biologija     Open Access  
Biology     Open Access   (Followers: 3)

        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  [2349 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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