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  Subjects -> MEDICAL SCIENCES (Total: 7879 journals)
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MEDICAL SCIENCES (2051 journals)                  1 2 3 4 5 6 7 8 | Last

Showing 1 - 200 of 3562 Journals sorted alphabetically
16 de Abril     Open Access  
3D Printing in Medicine     Open Access   (Followers: 1)
AADE in Practice     Hybrid Journal   (Followers: 5)
ABCS Health Sciences     Open Access   (Followers: 3)
Abia State University Medical Students' Association Journal     Full-text available via subscription  
ACIMED     Open Access   (Followers: 1)
ACS Medicinal Chemistry Letters     Hybrid Journal   (Followers: 42)
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 (Hradec Králové)     Open Access  
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 International     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: 4)
Acupuncture and Natural Medicine     Open Access  
Addiction Science & Clinical Practice     Open Access   (Followers: 8)
Addictive Behaviors Reports     Open Access   (Followers: 8)
Adıyaman Üniversitesi Sağlık Bilimleri Dergisi / Health Sciences Journal of Adıyaman University     Open Access  
Adnan Menderes Üniversitesi Sağlık Bilimleri Fakültesi Dergisi     Open Access  
Advanced Biomedical Research     Open Access  
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: 29)
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: 26)
Advances in Medical Ethics     Open Access  
Advances in Medical Research     Open Access  
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: 3)
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: 6)
Advances in Protein Chemistry and Structural Biology     Full-text available via subscription   (Followers: 20)
Advances in Regenerative Medicine     Open Access   (Followers: 3)
Advances in Skeletal Muscle Function Assessment     Open Access  
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: 11)
Aerospace Medicine and Human Performance     Full-text available via subscription   (Followers: 11)
African Health Sciences     Open Access   (Followers: 3)
African Journal of Biomedical Research     Open Access   (Followers: 1)
African Journal of Clinical and Experimental Microbiology     Open Access   (Followers: 2)
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   (Followers: 1)
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)
Althea Medical Journal     Open Access  
American Journal of Biomedical Engineering     Open Access   (Followers: 13)
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: 7)
American Journal of Family Therapy     Hybrid Journal   (Followers: 11)
American Journal of Law & Medicine     Full-text available via subscription   (Followers: 11)
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: 4)
American Journal of Medicine     Hybrid Journal   (Followers: 47)
American Journal of Medicine and Medical Sciences     Open Access   (Followers: 1)
American Journal of Medicine Studies     Open Access   (Followers: 1)
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: 9)
American medical news     Free   (Followers: 3)
American Medical Writers Association Journal     Full-text available via subscription   (Followers: 5)
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: 5)
Anatolian Clinic the Journal of Medical Sciences     Open Access  
Anatomica Medical Journal     Open Access  
Anatomical Science International     Hybrid Journal   (Followers: 3)
Anatomical Sciences Education     Hybrid Journal   (Followers: 1)
Anatomy     Open Access   (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)
Ankara Üniversitesi Tıp Fakültesi Mecmuası     Open Access  
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: 17)
Annals of Biomedical Sciences     Full-text available via subscription   (Followers: 3)
Annals of Clinical Microbiology and Antimicrobials     Open Access   (Followers: 11)
Annals of Family Medicine     Open Access   (Followers: 14)
Annals of Health Research     Open Access  
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: 11)
Annals of Nigerian Medicine     Open Access   (Followers: 1)
Annals of Rehabilitation Medicine     Open Access  
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: 23)
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   (Followers: 1)
Archives Medical Review Journal / Arşiv Kaynak Tarama Dergisi     Open Access  
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 Medicine and Surgery     Open Access  
Archives of Trauma Research     Open Access   (Followers: 3)
Archivos de Medicina (Manizales)     Open Access  
ArgoSpine News & Journal     Hybrid Journal  
Arquivos Brasileiros de Oftalmologia     Open Access   (Followers: 1)
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: 13)
Arterial Hypertension     Open Access   (Followers: 1)
Artificial Intelligence in Medicine     Hybrid Journal   (Followers: 14)
Artificial Organs     Hybrid Journal   (Followers: 1)
ASHA Leader     Open Access  
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 Biomedicine     Open Access   (Followers: 2)
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: 4)
Asian Journal of Medical and Pharmaceutical Researches     Open Access   (Followers: 1)
Asian Journal of Medical Sciences     Open Access   (Followers: 2)
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)
Atti della Accademia Peloritana dei Pericolanti - Classe di Scienze Medico-Biologiche     Open Access  
Audiology - Communication Research     Open Access   (Followers: 10)
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  
Avicenna     Open Access   (Followers: 3)
Avicenna Journal of Clinical Medicine     Open Access  
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: 4)

        1 2 3 4 5 6 7 8 | Last

Journal Cover
Annals of Biomedical Engineering
Journal Prestige (SJR): 1.042
Citation Impact (citeScore): 3
Number of Followers: 17  
 
  Hybrid Journal Hybrid journal (It can contain Open Access articles)
ISSN (Print) 1573-9686 - ISSN (Online) 0090-6964
Published by Springer-Verlag Homepage  [2352 journals]
  • Classification of Tumor Epithelium and Stroma by Exploiting Image Features
           Learned by Deep Convolutional Neural Networks
    • Authors: Yue Du; Roy Zhang; Abolfazl Zargari; Theresa C. Thai; Camille C. Gunderson; Katherine M. Moxley; Hong Liu; Bin Zheng; Yuchen Qiu
      Pages: 1988 - 1999
      Abstract: The tumor–stroma ratio (TSR) reflected on hematoxylin and eosin (H&E)-stained histological images is a potential prognostic factor for survival. Automatic image processing techniques that allow for high-throughput and precise discrimination of tumor epithelium and stroma are required to elevate the prognostic significance of the TSR. As a variant of deep learning techniques, transfer learning leverages nature-images features learned by deep convolutional neural networks (CNNs) to relieve the requirement of deep CNNs for immense sample size when handling biomedical classification problems. Herein we studied different transfer learning strategies for accurately distinguishing epithelial and stromal regions of H&E-stained histological images acquired from either breast or ovarian cancer tissue. We compared the performance of important deep CNNs as either a feature extractor or as an architecture for fine-tuning with target images. Moreover, we addressed the current contradictory issue about whether the higher-level features would generalize worse than lower-level ones because they are more specific to the source-image domain. Under our experimental setting, the transfer learning approach achieved an accuracy of 90.2 (vs. 91.1 for fine tuning) with GoogLeNet, suggesting the feasibility of using it in assisting pathology-based binary classification problems. Our results also show that the superiority of the lower-level or the higher-level features over the other ones was determined by the architecture of deep CNNs.
      PubDate: 2018-12-01
      DOI: 10.1007/s10439-018-2095-6
      Issue No: Vol. 46, No. 12 (2018)
       
  • Contractility of Airway Smooth Muscle Cell in Response to Zinc Oxide
           Nanoparticles by Traction Force Microscopy
    • Authors: Feng Lin; Haihui Zhang; Jianyong Huang; Chunyang Xiong
      Pages: 2000 - 2011
      Abstract: Zinc oxide nanoparticles (ZnO-NPs) have been widely used in engineering and biomedicine. However, their adverse pathological effects and mechanisms, especially the biomechanical effects on respiratory system where airway smooth muscle cell (ASMC) contractility regulates the airway response and lung function, are not fully understood. Herein, we used traction force microscopy (TFM) method to investigate whether ZnO-NPs of different concentrations (0.1–10 μg/mL) can alter ASMC contractility (basal and agonist-stimulated) after a short-term exposure and the potential mechanisms. We found that ZnO-NPs exposure led to a decrease of ASMC viability in a dose-dependent manner. Notably, basal contractility was enhanced when the concentration of ZnO-NPs was less than 0.1 μg/mL and decreased afterwards, while KCl-stimulated contractility was reduced in all cases of ZnO-NPs treated groups. Cytoskeleton structure was also found to be significantly altered in ASMC with the stimulation of ZnO-NPs. More importantly, it seems that ZnO-NPs with low concentration (< 0.1 μg/mL) would change ASMC contractility without any apparent cytotoxicity through disruption of the microtubule assembly. Moreover, our results also emerged that ASMC contractility responses were regulated by clathrin-mediated endocytosis and cytoskeleton remodeling. Together, these findings indicate the susceptibility of cell mechanics to NPs exposure, suggesting that cell mechanical testing will contribute to uncover the pathological mechanisms of NPs in respiratory diseases.
      PubDate: 2018-12-01
      DOI: 10.1007/s10439-018-2098-3
      Issue No: Vol. 46, No. 12 (2018)
       
  • Optimal Design of Needle Array for Effective Drug Delivery
    • Authors: Hanwook Park; Hyejeong Kim; Sang Joon Lee
      Pages: 2012 - 2022
      Abstract: Recently, the multi-needle drug injection has been adopted to overcome the shortcomes of conventional single-needle injection, enhancing the efficiency of drug delivery. However, the effect of needle array on the efficacy of drug delivery has not been fully elucidated. In this study, the interactions of drug analogous solution injected from a pair of needles were analyzed to examine the design criteria of effective multi-needle devices for drug delivery. Temporal and spatial variations of relative contents of the solution in the tissues were compared according to the distance between two adjacent needles (DN). As the DN increases from 5 to 20 D, where D is the needle diameter, the solution from each needle encounters 3.5 times faster, and 4.22 times more solution was accumulated. At the same time, the effective spreading area was continuously increased from 54.2 to 177.8 mm2 and RCS gradient decreases from 0.087 to 0.037, due to the overlapping effect of the spreading solution from neighboring needles. Finally, based on the experimental results, an optimal design criterion of needle array for effective drug delivery was proposed. The present results would be helpful in the design of multi-needle injection devices and eventually offer advantage to patients with effective drug delivery.
      PubDate: 2018-12-01
      DOI: 10.1007/s10439-018-2100-0
      Issue No: Vol. 46, No. 12 (2018)
       
  • Computational Fluid Dynamics Study of the Effects of Surface Roughness on
           Permeability and Fluid Flow-Induced Wall Shear Stress in Scaffolds
    • Authors: Davar Ali; Sadri Sen
      Pages: 2023 - 2035
      Abstract: In this work, we investigated surface roughness effects on bone scaffold permeability and fluid flow-induced wall shear stress (WSS) using computational fluid dynamics (CFD) analysis. Scaffolds are made of interconnected microchannels, whose fluid flow can be examined from the perspective of fluid flow dynamics. Given that the roughness of microchannel surfaces serves a non-negligible function in the fluid dynamics within the channels, it is believed that the wall roughness of scaffolds can play an important role in their permeability and WSS. Given the criticality of permeability and WSS in the effective biological functioning of scaffolds, we investigated manufacturing-induced surface roughness effects on the two aforementioned biocompatibility characteristics. To this end, three scaffolds with square pores of different sizes (300, 600, and 900 µm) and identical porosity (63%) were designed. Six roughness levels (0, 4, 8, 12, 16, and 20 µm) were established for the scaffold walls, thus enabling us to develop 18 scaffold models. The pressure drop and WSS in the scaffolds were then measured by CFD. Scaffold permeability was calculated using Darcy’s law, with reference to geometrical parameters and the pressure drop derived from the CFD analysis. In all the scaffolds, high roughness decreased permeability and WSS. A significant difference in WSS reduction was found between the models with smooth scaffolds and the models with scaffolds that had a roughness of 20 µm. Except for the scaffold with a pore size of 300 µm, all the others showed no considerable change in permeability at different roughness levels.
      PubDate: 2018-12-01
      DOI: 10.1007/s10439-018-2101-z
      Issue No: Vol. 46, No. 12 (2018)
       
  • Sex Differences in 2-DOF Human Ankle Stiffness in Relaxed and Contracted
           Muscles
    • Authors: Jessica Trevino; Hyunglae Lee
      Pages: 2048 - 2056
      Abstract: Ankle stiffness has been known as one of the most important components contributing to the maintenance of lower body stability during postural balance and locomotion. It has been repeatedly shown that women have lower stability and increased risk of injury when compared to men participating in similar sports activities, yet sex differences in neuromuscular control of the ankle, including the modulation of ankle stiffness, and their contribution to stability remain unknown. To identify sex differences in human ankle stiffness, this study quantified multi-dimensional ankle stiffness in 20 young, healthy men and 20 young, healthy women over a range of ankle muscle contractions, from relaxed to 20% of maximum voluntary co-contraction of ankle muscles. A wearable ankle robot and a system identification method were used to reliably quantify ankle stiffness in a 2-dimensional space spanning the sagittal plane and the frontal plane. In all muscle activation levels, significant sex differences in ankle stiffness were identified in both the sagittal and frontal planes. In the given experimental conditions, ankle stiffness in males was higher than females up to 15.1 and 8.3 Nm/rad in the sagittal plane and the frontal plane, respectively. In addition, sex differences in the spatial structure of ankle stiffness were investigated by quantifying three parameters defining the stiffness ellipse of the ankle: area, aspect ratio, and orientation. In all muscle activation levels, a significant sex difference was identified in the area of stiffness ellipse as expected from the sex difference in the sagittal and frontal planes. However, no statistical sex difference was observed in the aspect ratio and orientation, which would be due to little differences in major anatomical configurations of the ankle joint between sexes. This study, in combination with future studies investigating sex differences during dynamic tasks (e.g. postural balance and locomotion) would serve as a basis to develop a risk assessment tool and sex-specific training programs for efficient ankle injury prevention or rehabilitation.
      PubDate: 2018-12-01
      DOI: 10.1007/s10439-018-2092-9
      Issue No: Vol. 46, No. 12 (2018)
       
  • A Wearable Magnet-Based System to Assess Activity and Joint Flexion in
           Humans and Large Animals
    • Authors: Feini Qu; Brendan D. Stoeckl; Peter M. Gebhard; Todd J. Hullfish; Josh R. Baxter; Robert L. Mauck
      Pages: 2069 - 2078
      Abstract: Functional outcomes, such as joint flexion and gait, are important indicators of efficacy in musculoskeletal research. Current technologies that objectively assess these parameters, including visual tracking systems and force plates, are challenging to deploy in long-term translational and clinical studies. To that end, we developed a wearable device that measures both physical activity and joint flexion using a single integrated sensor and magnet system, and hypothesized that it could evaluate post-operative functional recovery in an unsupervised setting. To demonstrate the feasibility of measuring joint flexion, we first compared knee motion from the wearable device to that acquired from a motion capture system to confirm that knee flexion measurements during normal human gait, predicted via changes in magnetic field strength, closely correlated with data acquired by motion capture. Using this system, we then monitored a porcine cohort after bilateral stifle arthrotomy to investigate longitudinal changes in physical activity and joint flexion. We found that unsupervised activity declined immediately after surgery, with a return to pre-operative activity occurring over a period of 2 weeks. By providing objective, individualized data on locomotion and joint function, this magnet-based system will facilitate the in vivo assessment of novel therapeutics in translational orthopaedic research.
      PubDate: 2018-12-01
      DOI: 10.1007/s10439-018-2105-8
      Issue No: Vol. 46, No. 12 (2018)
       
  • Wearable Water Content Sensor Based on Ultrasound and Magnetic Sensing
    • Authors: Song Zhang; Rajesh Rajamani; A. Serdar Sezen
      Pages: 2079 - 2090
      Abstract: Fluid accumulation in the lower extremities is an early indicator of disease deterioration in cardiac failure, chronic venous insufficiency and lymphedema. At-home wearable monitoring and early detection of fluid accumulation can potentially lead to prompt medical intervention and avoidance of hospitalization. Current methods of fluid accumulation monitoring either suffer from lack of specificity and sensitivity or are invasive and cost-prohibitive to use on a daily basis. Ultrasound velocity in animal and human tissue has been found to change with water content. However, previous prototype fluid monitoring sensors based on ultrasound are cumbersome and not wearable. Hence, in this research a compact water content sensor based on a wearable instrumented elastic band is proposed. A novel integration of magnetic sensing and ultrasonic sensing is utilized, where the magnetic sensor provides distance measurement and the ultrasonic sensor produces time-of-flight measurement. Magnetic field modeling with a Kalman filter and least squares linear fitting algorithms are employed to ensure robust sensor performance on a wearable device. The combination of the two measurements yields ultrasound velocity measurement in tissue. The water content sensor prototype was tested on a tissue phantom, on animal tissue and on a human leg. The error in velocity measurement is shown to be small enough for early detection of tissue edema.
      PubDate: 2018-12-01
      DOI: 10.1007/s10439-018-02108-w
      Issue No: Vol. 46, No. 12 (2018)
       
  • A Combined Approach for the Analysis of Ocular Fluid Dynamics in the
           Presence of Saccadic Movements
    • Authors: Marco Ferroni; Matteo Giuseppe Cereda; Federica Boschetti
      Pages: 2091 - 2101
      Abstract: One of the main ocular diseases is age-related macular degeneration, actually treated with antibodies injections into the eye. This problem has been faced by computational approaches, taking into account either the influence of the tissues surrounding the vitreous, or the saccades. The aim of this work is to propose a combined fluid dynamic model of the vitreous chamber that analyses the impact of the saccades on the fluid dynamic mechanisms. The ocular vitreous humor was modeled considering liquefaction occurring in presence of age-related macular degeneration. We identified two kinds of boundary conditions, one related to the physiological environment outside the chamber, and one related to the saccades. The scleral hydraulic conductivity was evaluated by means of experimental permeability tests. An exponential decay was used to describe the trend of the scleral hydraulic conductivity with the acting pressure drop. The streamline analysis shows two main stagnant regions on the equatorial plane and peculiar fluid dynamics in absence of saccades. This study demonstrates the major role played by the saccades in determining the fluid dynamic mechanisms inside the vitreous chamber of the eye and represents a powerful tool to investigate vitreous dynamics and its relation to clinical issues.
      PubDate: 2018-12-01
      DOI: 10.1007/s10439-018-02110-2
      Issue No: Vol. 46, No. 12 (2018)
       
  • On the Significance of Systolic Flow Waveform on Aortic Valve Energy Loss
    • Authors: Hoda Hatoum; Brandon L. Moore; Lakshmi Prasad Dasi
      Pages: 2102 - 2111
      Abstract: This study aims to quantitatively and qualitatively assess energy dissipation in the aortic valve as a function of systolic aortic flow waveform representing pathologies where flow time-to-peak is delayed. A bioprosthetic valve was tested in the aortic position of a left-heart simulator under physiological pressure and flow conditions. The flow loop piston pump was programmed to generate three different flow waveforms each with a different peak time annotated as early peak (EP) with a rapid acceleration, mid peak (MP) and late peak (LP) with a rapid deceleration. Energy dissipation was calculated from flow and pressure measurements while sinus vorticity dynamics were evaluated using time-resolved planar particle image velocimetry. Average pressure gradients during systole are found 30.2 ± 0.19, 30.7 ± 0.25 and 32.9 ± 0.29 mmHg and average dissipation over systole is found 0.95 ± 0.026, 1.05 ± 0.034 and 1.25 ± 0.043 W for EP, MP and LP respectively. As systole’s acceleration phase is slower, sinus vortices are more likely to form, necessitating more energy exchange from shear layers inducing more viscous dissipation. EP found in healthy individuals is superior in terms of reducing energy dissipation and increasing aortic valve efficiency. In the context of possible left ventricular dysfunction and aortic stenosis, this means that delayed time-to-peak in the aortic flow waveform seen is not compensatory.
      PubDate: 2018-12-01
      DOI: 10.1007/s10439-018-2102-y
      Issue No: Vol. 46, No. 12 (2018)
       
  • Comparison of Flow Estimators for Rotary Blood Pumps: An In Vitro and In
           Vivo Study
    • Authors: Anastasios Petrou; Daniel Kuster; Jongseok Lee; Mirko Meboldt; Marianne Schmid Daners
      Pages: 2123 - 2134
      Abstract: Various approaches for estimating the flow rate of a rotary blood pump have been proposed for monitoring and control purposes. They have been evaluated under different test conditions and, therefore, a direct comparison among them is difficult. Furthermore, a limited performance has been reported for the areas where the pump flow and motor current present a non-monotonic relationship. In this regard, we selected most approaches that have been presented in literature and added a modified one, resulting in four estimators, which are either non-invasive or invasive, i.e., inlet and outlet pump pressure sensors are used. Data from in vitro and in vivo studies with the Deltastream pump DP2 were used to compare the estimators under the same test conditions. These data included both constant and varying pre- and afterload, contractility, viscosity, as well as pump speed settings. Bland–Altman plots were used to evaluate the performance of the estimators. The mean error of the overall estimated flow in vitro ranged from 0.002 to 0.38 L/min and the limits of agreement (LoA) between ± 2 L/min. During negative flows the mean error decreased by about 25% when the pump inlet pressure was added as an input. In vivo, the mean errors increased, while the LoA remained in the same range. An estimator based on pump pressure difference improves the reliability in areas where flow and current relationship is not monotonic. A trade-off between estimation accuracy and number of sensors was identified. The estimation objective and the potential errors should be considered when selecting an estimation approach and designing the pump systems.
      PubDate: 2018-12-01
      DOI: 10.1007/s10439-018-2106-7
      Issue No: Vol. 46, No. 12 (2018)
       
  • A Numerical Preoperative Planning Model to Predict Arterial Deformations
           in Endovascular Aortic Aneurysm Repair
    • Authors: Hossein Mohammadi; Simon Lessard; Eric Therasse; Rosaire Mongrain; Gilles Soulez
      Pages: 2148 - 2161
      Abstract: Endovascular aneurysm repair is rapidly emerging as the primary preferred method for treating abdominal aortic aneurysm. In this image-guided interventional procedure, to obtain the roadmap and decrease contrast injections, preoperative CT images are overlaid onto live fluoroscopy images using various 2D/3D image fusion techniques. However, the structural changes due to the insertion of stiff tools degrade the fusion accuracy. To correct the mismatch and quantify the intraoperative deformations, we present a patient-specific biomechanical model of the aorto-iliac structure and its surrounding tissues. The predictive capability of the model was evaluated against intraoperative data for a group of four patients. Incorporating the perivascular tissues into the model significantly improved the results and the mean distance between the real and simulated endovascular tools was 2.99 ± 1.78 mm on the ipsilateral side and 4.59 ± 3.25 mm on the contralateral side. Moreover, the distance between the deformed iliac ostia and their corresponding landmarks on intraoperative images was 2.99 ± 2.48 mm.
      PubDate: 2018-12-01
      DOI: 10.1007/s10439-018-2093-8
      Issue No: Vol. 46, No. 12 (2018)
       
  • Region-Specific Microstructure in the Neonatal Ventricles of a Porcine
           Model
    • Authors: F. Ahmad; S. Soe; N. White; R. Johnston; I. Khan; J. Liao; M. Jones; R. Prabhu; I. Maconochie; Peter Theobald
      Pages: 2162 - 2176
      Abstract: The neonate transitions from placenta-derived oxygen, to supply from the pulmonary system, moments after birth. This requires a series of structural developments to divert more blood through the right heart and onto the lungs, with the tissue quickly remodelling to the changing ventricular workload. In some cases, however, the heart structure does not fully develop causing poor circulation and inefficient oxygenation, which is associated with an increase in mortality and morbidity. This study focuses on developing an enhanced knowledge of the 1-day old heart, quantifying the region-specific microstructural parameters of the tissue. This will enable more accurate mathematical and computational simulations of the young heart. Hearts were dissected from 12, 1-day-old deceased Yorkshire piglets (mass: 2.1–2.4 kg, length: 0.38–0.51 m), acquired from a breeding farm. Evans blue dye was used to label the heart equator and to demarcate the left and right ventricle free walls. Two hearts were used for three-dimensional diffusion-tensor magnetic resonance imaging, to quantify the fractional anisotropy (FA). The remaining hearts were used for two-photon excited fluorescence and second-harmonic generation microscopy, to quantify the cardiomyocyte and collagen fibril structures within the anterior and posterior aspects of the right and left ventricles. FA varied significantly across both ventricles, with the greatest in the equatorial region, followed by the base and apex. The FA in each right ventricular region was statistically greater than that in the left. Cardiomyocyte and collagen fibre rotation was greatest in the anterior wall of both ventricles, with less dispersion when compared to the posterior walls. In defining these key parameters, this study provides a valuable insight into the 1-day-old heart that will provide a valuable platform for further investigation the normal and abnormal heart using mathematical and computational models.
      PubDate: 2018-12-01
      DOI: 10.1007/s10439-018-2089-4
      Issue No: Vol. 46, No. 12 (2018)
       
  • Simulating Developmental Cardiac Morphology in Virtual Reality Using a
           Deformable Image Registration Approach
    • Authors: Arash Abiri; Yichen Ding; Parinaz Abiri; René R. Sevag Packard; Vijay Vedula; Alison Marsden; C.-C. Jay Kuo; Tzung K. Hsiai
      Pages: 2177 - 2188
      Abstract: While virtual reality (VR) has potential in enhancing cardiovascular diagnosis and treatment, prerequisite labor-intensive image segmentation remains an obstacle for seamlessly simulating 4-dimensional (4-D, 3-D + time) imaging data in an immersive, physiological VR environment. We applied deformable image registration (DIR) in conjunction with 3-D reconstruction and VR implementation to recapitulate developmental cardiac contractile function from light-sheet fluorescence microscopy (LSFM). This method addressed inconsistencies that would arise from independent segmentations of time-dependent data, thereby enabling the creation of a VR environment that fluently simulates cardiac morphological changes. By analyzing myocardial deformation at high spatiotemporal resolution, we interfaced quantitative computations with 4-D VR. We demonstrated that our LSFM-captured images, followed by DIR, yielded average dice similarity coefficients of 0.92 ± 0.05 (n = 510) and 0.93 ± 0.06 (n = 240) when compared to ground truth images obtained from Otsu thresholding and manual segmentation, respectively. The resulting VR environment simulates a wide-angle zoomed-in view of motion in live embryonic zebrafish hearts, in which the cardiac chambers are undergoing structural deformation throughout the cardiac cycle. Thus, this technique allows for an interactive micro-scale VR visualization of developmental cardiac morphology to enable high resolution simulation for both basic and clinical science.
      PubDate: 2018-12-01
      DOI: 10.1007/s10439-018-02113-z
      Issue No: Vol. 46, No. 12 (2018)
       
  • Modeling the Evans Blue Dilution Method for the Measurement of Plasma
           Volume in Small Animals: A New Optimized Method
    • Authors: Jean-Paul Richalet; Dominique Marchant; Jose-Luis Macarlupu; Nicolas Voituron
      Pages: 2189 - 2195
      Abstract: The measurement of plasma volume (Vp) in humans and animals is frequently performed by the Evans blue dye dilution method. However, after injection of Evans blue into the circulation, no steady state is observed because of delayed mixing and progressive leakage of dye out of vascular space. Various methods of calculation have been proposed, either with a single blood sampling 5–10 min after dye injection (Single point method), or with extrapolation at time zero of a logarithmic decay (Log linear method). We propose a method based on a two-compartment hypothesis taking into account the initial mixing and the leakage phase in the time course of dye concentration. Nineteen Sprague–Dawley rats were studied in various conditions and blood sampling was performed before and 2, 4 and 6 min after injection of 200 μg Evans blue. A mathematical model was designed to describe the two-compartment hypothesis and allowed the calculation of Vp and Kout (rate of disappearance of dye from vascular space). A Bland and Altman representation evidenced an overestimation of Vp with previous methods and the great dispersion of results with the single point method, especially when using the 6 min point. Calculation of Kout revealed more accurate with the model than the Log linear method, especially when the mixing rate is slow. We suggest using the two-compartment model to measure Vp with Evans blue technique in rats. This method also allows precise evaluation of the rate of dye leakage, which could be a good marker of vascular permeability to albumin.
      PubDate: 2018-12-01
      DOI: 10.1007/s10439-018-02114-y
      Issue No: Vol. 46, No. 12 (2018)
       
  • Harnessing Macrophages for Vascularization in Tissue Engineering
    • Authors: Erika M. Moore; Jennifer L. West
      Abstract: In this review, we explore the roles of macrophages both in vessel development and in vascularization of tissue engineered constructs. Upon the implantation of tissue engineered constructs into the body, macrophages respond, invade and orchestrate the host’s immune response. By altering their phenotype, macrophages can adopt a variety of roles. They can promote inflammation at the site of the implanted construct; they can also promote tissue repair. Macrophages support tissue repair by promoting angiogenesis through the secretion of pro-angiogenic cytokines and by behaving as support cells for nascent vasculature. Thus, the ability to manipulate the macrophage phenotype may yield macrophages capable of supporting vessel development. Moreover, macrophages are an easily isolated autologous cell source. For the generation of vascularized constructs outside of the body, these isolated macrophages can also be skewed to adopt a pro-angiogenic phenotype and enhance blood vessel development in the presence of endothelial cells. To assess the influence of macrophages on vessel development, both in vivo and in vitro models have been developed. Additionally, several groups have demonstrated the pro-angiogenic roles of macrophages in vascularization of tissue engineered constructs through the manipulation of macrophage phenotypes. This review comments on the roles of macrophages in promoting vascularization within these contexts.
      PubDate: 2018-12-07
      DOI: 10.1007/s10439-018-02170-4
       
  • Quantification of Cerebellar Crowding in Type I Chiari Malformation
    • Authors: Dipankar Biswas; Maggie S. Eppelheimer; James R. Houston; Alaaddin Ibrahimy; J. Rajiv Bapuraj; Richard Labuda; Philip A. Allen; David Frim; Francis Loth
      Abstract: This study was focused on a semi-automated morphometric analysis of the cerebellum in the mid-sagittal plane as an alternative to tonsillar descent alone in the evaluation of Chiari malformation type 1 (CMI) patients. Morphometric analyses of posterior fossa structures were performed on mid-sagittal MRI images of 375 individuals (females, > 18 years, 235 CMI and 140 healthy controls). Twenty-six parameters including linear, angular and area measurements together with non-dimensional ratios were calculated. Eighteen parameters were found to be significantly different between CMI and control subjects. Smaller posterior cranial fossa (PCF) area in CMI subjects was attributed to a smaller PCF area anterior to the brainstem. The cerebellar area was found to be larger in CMI subjects as compared to controls (15.1%), even without inclusion of the tonsillar area below the foramen magnum (FM) (8.4%). The larger cerebellar area in CMI subjects was due to cranial–caudal elongation of the cerebellum, predominately below the fastigium. The cerebrospinal fluid spaces below the FM were smaller in CMI subjects as compared to controls. Overall, greater cerebellar crowding was identified in CMI subjects relative to healthy controls. These observations may improve our understanding of the pathophysiology of CMI in adult female patients.
      PubDate: 2018-12-07
      DOI: 10.1007/s10439-018-02175-z
       
  • Effect of Tissue Material Properties in Blast Loading: Coupled
           Experimentation and Finite Element Simulation
    • Authors: Molly T. Townsend; Eren Alay; Maciej Skotak; Namas Chandra
      Abstract: Computational models of blast-induced traumatic brain injury (bTBI) require a robust definition of the material models of the brain. The mechanical constitutive models of these tissues are difficult to characterize, leading to a wide range of values reported in literature. Therefore, the sensitivity of the intracranial pressure (ICP) and maximum principal strain to variations in the material model of the brain was investigated through a combined computational and experimental approach. A finite element model of a rat was created to simulate a shock wave exposure, guided by the experimental measurements of rats subjected to shock loading conditions corresponding to that of mild traumatic brain injury in a field-validated shock tube. In the numerical model, the properties of the brain were parametrically varied. A comparison of the ICP measured at two locations revealed that experimental and simulated ICP were higher in the cerebellum (p < 0.0001), highlighting the significance of pressure sensor locations within the cranium. The ICP and strain were correlated with the long-term bulk (p < 0.0001) and shear moduli (p < 0.0001), with an 80 MPa effective bulk modulus value matching best with experimental measurements. In bTBI, the solution is sensitive to the brain material model, necessitating robust validation methods.
      PubDate: 2018-12-06
      DOI: 10.1007/s10439-018-02178-w
       
  • Objective Evaluation of Whole Body Kinematics in a Simulated, Restrained
           Frontal Impact
    • Authors: Jeremy M. Schap; Bharath Koya; F. Scott Gayzik
      Abstract: The use of human body models as an additional data point in the evaluation of human-machine interaction requires quantitative validation. In this study a validation of the Global Human Body Models Consortium (GHBMC) average male occupant model (M50-O v. 4.5) in a restrained frontal sled test environment is presented. For vehicle passengers, frontal crash remains the most common mode, and the most common source of fatalities. A total of 55-time history traces of reaction loads and kinematics from the model were evaluated against corresponding PMHS data (n = 5). Further, the model’s sensitivity to the belt path was studied by replicating two documented PMHS cases with prominent lateral and medial belt paths respectively. Results were quantitatively evaluated using open source CORA software. A tradeoff was observed; better correlation scores were achieved on gross measures (e.g. reaction loads), whereas better corridor scores were achieved on localized measures (rib deflections), indicating that subject specificity may dominate the comparison at localized anatomical regions. On an overall basis, the CORA scores were 0.68, 0.66 and 0.60 for force, body kinematics and chest wall kinematics. Belt force responses received the highest grouped CORA score of 0.85. Head and sternum kinematics earning a 0.8 and 0.7 score respectively. The model demonstrated high sensitivity to belt path, resulting in a 20-point increase in CORA score when the belt was routed closer to analogous location of data collection. The human model demonstrated overall reasonable biofidelity and sensitivity to countermeasures in frontal crash kinematics.
      PubDate: 2018-12-06
      DOI: 10.1007/s10439-018-02180-2
       
  • Embedded Finite Elements for Modeling Axonal Injury
    • Authors: Harsha T. Garimella; Ritika R. Menghani; Jesse I. Gerber; Srikumar Sridhar; Reuben H. Kraft
      Abstract: The purpose of this paper is to propose and develop a large strain embedded finite element formulation that can be used to explicitly model axonal fiber bundle tractography from diffusion tensor imaging of the brain. Once incorporated, the fibers offer the capability to monitor tract-level strains that give insight into the biomechanics of brain injury. We show that one commercial software has a volume and mass redundancy issue when including embedded axonal fiber and that a newly developed algorithm is able to correct this discrepancy. We provide a validation analysis for stress and energy to demonstrate the method.
      PubDate: 2018-12-05
      DOI: 10.1007/s10439-018-02166-0
       
  • Development of a Second-Order System for Rapid Estimation of Maximum Brain
           Strain
    • Authors: Lee F. Gabler; Jeff R. Crandall; Matthew B. Panzer
      Abstract: Diffuse brain injuries are assessed with deformation-based criteria that utilize metrics based on rotational head kinematics to estimate brain injury severity. Although numerous metrics have been proposed, many are based on empirically-derived models that use peak kinematics, which often limit their applicability to a narrow range of head impact conditions. However, over a broad range of impact conditions, brain deformation response to rotational head motion behaves similarly to a second-order mechanical system, which utilizes the full kinematic time history of a head impact. This study describes a new brain injury metric called Diffuse Axonal Multi-Axis General Evaluation (DAMAGE). DAMAGE is based on the equations of motion of a three-degree-of-freedom, coupled 2nd-order system, and predicts maximum brain strain using the directionally dependent angular acceleration time-histories from a head impact. Parameters for the effective mass, stiffness, and damping were determined using simplified rotational pulses which were applied multiaxially to a 50th percentile adult human male finite element model. DAMAGE was then validated with a separate database of 1747 head impacts including helmet, crash, and sled tests and human volunteer responses. Relative to existing rotational brain injury metrics that were evaluated in this study, DAMAGE was found to be the best predictor of maximum brain strain.
      PubDate: 2018-12-04
      DOI: 10.1007/s10439-018-02179-9
       
 
 
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