Publications by authors named "Christopher L Jones"

7 Publications

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3-D printed Ti-6Al-4V scaffolds for supporting osteoblast and restricting bacterial functions without using drugs: Predictive equations and experiments.

Acta Biomater 2019 09 3;96:662-673. Epub 2019 Jul 3.

Department of Chemical Engineering, Northeastern University, Boston, MA 02115, USA. Electronic address:

Conditions resulting from musculoskeletal deficiencies (MSDs) are wide-ranging and retain the likelihood for restricting motion or producing pain, especially in the lower back, neck, and upper limbs. Engineered scaffold devices are being produced to replace antiquated modalities that suffer from structural and mechanical deficiencies in the treatment of MSDs. Here, as-fabricated Ti-6Al-4V-based Hive™ interbody fusion scaffolds, commercialized by HD Lifesciences LLC, were assayed for their osteogenicity and antibacterial potential using a series of characterization and in vitro tests, as well as by quantitative analyses. A topographical assessment of the Hive™ meshes indicated that the elementally pure substrates are microscopically porous and rough, in addition to displaying structural heterogeneity. Roughness estimations and static contact angle measurements recommended the use of the as-fabricated Ti-6Al-4V substrates for supporting osteoblast attachment, especially, due to the improved surface roughness and wettability values of these scaffolds relative to the unembellished Ti-6Al-4V surfaces. Quantitative correlations relating the surface properties of roughness and energy were applied to predict cellular behaviors. Cell growth suppositions were experimentally corroborated. Critical in vitro data indicated the competencies of the Hive™ scaffolds for promoting the adhesion and proliferation of human fetal osteoblasts (hFOBs), accumulating substantial calcium deposition from metabolizing hFOBs, and restricting the attachment of bacteria. The model system that investigated the pre-adsorption of casein proteins along the Hive™ test substrates additionally furthered the notion that bacterial attachment may be restricted, with short-scale adhesion dynamics serving as the theoretical basis for this hypothesis. In this manner, this study showed that through predictive models and experiments, these novel 3D printed Ti-based scaffolds can increase bone cell while decreasing bacteria functions without using drugs. STATEMENT OF SIGNIFICANCE: Sintered Ti-6Al-4V spinal fusion devices (Hive™) manufactured and marketed by HD Lifesciences LLC were assessed for their biocompatibility and antibacterial performance. A mixed methods approach was employed, whereby quantitative measures were used to predict the ability for Hive™ substrates to adsorb specialized proteins and to restrict bacterial surface colonization. In vitro tests that evaluated bone cell and bacterial adhesion, calcium deposition, and protein adsorption supported quantitative predictions. The data herein presented demonstrate the following: (1) surface energy is an important predictor of implant-cell interactions, (2) strong correlations exist between surface energy and surface roughness, (3) mathematical models can be used to improve and predict implant device perofrmance, and (4) porous, rough, 3D-printed materials perform well in terms of biocompatibility and antimicrobial efficacy.
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http://dx.doi.org/10.1016/j.actbio.2019.06.055DOI Listing
September 2019

Involuntary Neuromuscular Coupling between the Thumb and Finger of Stroke Survivors during Dynamic Movement.

Front Neurol 2018 1;9:84. Epub 2018 Mar 1.

UNC/NC State Joint Department of Biomedical Engineering, Rehabilitation Engineering Core, Raleigh, NC, United States.

Finger-thumb coordination is crucial to manual dexterity but remains incompletely understood, particularly following neurological injury such as stroke. While being controlled independently, the index finger and thumb especially must work in concert to perform a variety of tasks requiring lateral or palmar pinch. The impact of stroke on this functionally critical sensorimotor control during dynamic tasks has been largely unexplored. In this study, we explored finger-thumb coupling during close-open pinching motions in stroke survivors with chronic hemiparesis. Two types of perturbations were applied randomly to the index with a novel Cable-Actuated Finger Exoskeleton: a sudden joint acceleration stretching muscle groups of the index finger and a sudden increase in impedance in selected index finger joint(s). Electromyographic signals for specific thumb and index finger muscles, thumb tip trajectory, and index finger joint angles were recorded during each trial. Joint angle perturbations invoked reflex responses in the flexor digitorum superficialis (FDS), first dorsal interossei (FDI), and extensor digitorum communis muscles of the index finger and heteronymous reflex responses in flexor pollicis brevis of the thumb ( < 0.017). Phase of movement played a role as a faster peak reflex response was observed in FDI during opening than during closing ( < 0.002) and direction of perturbations resulted in shorter reflex times for FDS and FDI ( < 0.012) for extension perturbations. Surprisingly, when index finger joint impedance was suddenly increased, thumb tip movement was substantially increased, from 2 to 10 cm ( < 0.001). A greater effect was seen during the opening phase ( < 0.044). Thus, involuntary finger-thumb coupling was present during dynamic movement, with perturbation of the index finger impacting thumb activity. The degree of coupling modulated with the phase of motion. These findings reveal a potential mechanism for direct intervention to improve poststroke hand mobility and provide insight on prospective neurologically oriented therapies.
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http://dx.doi.org/10.3389/fneur.2018.00084DOI Listing
http://www.ncbi.nlm.nih.gov/pmc/articles/PMC5837983PMC
March 2018

Design and Evaluation of an Actuated Exoskeleton for Examining Motor Control in Stroke Thumb.

Adv Robot 2016;30(3):165-177. Epub 2016 Mar 7.

Department of Mechanical Engineering, Vanderbilt University, Nashville, TN, USA 37212.

Chronic hand impairment is common following stroke. This paper presents an actuated thumb exoskeleton (ATX) to facilitate research in examining motor control and hand rehabilitation. The ATX presented in this work aims to provide independent bi-directional actuation in each of the 5 degrees-of-freedom (DOF) of the thumb using a novel flexible shaft based mechanism that has 5 active DOF and 3 passive DOF. A prototype has been built and experiments have been conducted to measure the allowable workspace at the thumb and evaluate the kinematic and kinetic performance of the ATX. The experimental results show that the ATX is able to provide individual actuation at all 5 thumb joints with high joint velocity and torque capacities. Further improvement and future work are discussed.
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http://dx.doi.org/10.1080/01691864.2015.1105867DOI Listing
http://www.ncbi.nlm.nih.gov/pmc/articles/PMC5035118PMC
March 2016

Assessing a doctor you've rarely worked with: The use of workplace-based assessments in a busy inner city emergency department.

Emerg Med Australas 2016 Aug 26;28(4):439-43. Epub 2016 May 26.

Department of Emergency Medicine, Royal Perth Hospital, Perth, Western Australia, Australia.

Objective: Historically, end-of-term assessments for Junior Medical Officers in our ED have been completed by nominated Consultants based on varying amounts of observation in addition to feedback from other health professionals. Our hypothesis is that this system of assessment is both inconsistent and unreliable. Our objective was to increase the validity of our assessment process using workplace-based assessments linked specifically to the domains set out in the Australian Medical Council intern assessment form.

Methods: Current practice was established using an online survey. Workplace-based assessments were then performed on each junior doctor throughout the course of a term. A repeat survey at the end of term was used to audit the use of the workplace-based assessments and their effect on the adequacy of the assessments.

Results: Almost three quarters of our Consultants used workplace-based assessments as part of their end-of-term assessment. Overall, 80% of Consultants agreed that the Junior Medical Officers assessment process was improved when using workplace-based assessments as an adjunct.

Conclusion: Workplace-based assessments improve the validity of end-of-term assessments for junior doctors in an ED as perceived by those performing the assessment.
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http://dx.doi.org/10.1111/1742-6723.12589DOI Listing
August 2016

Intensive care in a private hospital: An option for emergency medicine trainees?

Emerg Med Australas 2015 Dec 29;27(6):621. Epub 2015 Sep 29.

Saint John of God Subiaco Hospital, Perth, WA, Australia.

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http://dx.doi.org/10.1111/1742-6723.12489DOI Listing
December 2015

Design and Development of the Cable Actuated Finger Exoskeleton for Hand Rehabilitation Following Stroke.

IEEE ASME Trans Mechatron 2014 Feb 16;19(1):131-140. Epub 2012 Nov 16.

Department of Biomedical Engineering, Illinois Institute of Technology, Chicago, IL 60616 USA; Rehabilitation Institute of Chicago, Chicago, IL 60611 USA

Finger impairment following stroke results in significant deficits in hand manipulation and the performance of everyday tasks. While recent advances in rehabilitation robotics have shown promise for facilitating functional improvement, it remains unclear how best to employ these devices to maximize benefits. Current devices for the hand, however, lack the capacity to fully explore the space of possible training paradigms. Particularly, they cannot provide the independent joint control and levels of velocity and torque required. To fill this need, we have developed a prototype for one digit, the cable actuated finger exoskeleton (CAFE), a three-degree-of-freedom robotic exoskeleton for the index finger. This paper presents the design and development of the CAFE, with performance testing results.
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http://dx.doi.org/10.1109/TMECH.2012.2224359DOI Listing
http://www.ncbi.nlm.nih.gov/pmc/articles/PMC6419777PMC
February 2014

Physical activity in women with polycystic ovary syndrome: prevalence, predictors, and positive health associations.

Am J Obstet Gynecol 2011 Apr 2;204(4):352.e1-6. Epub 2011 Feb 2.

Division of Reproductive Endocrinology and Infertility, Department of Obstetrics, Gynecology, and Reproductive Sciences, University of California, San Francisco, School of Medicine, San Francisco, CA, USA.

Objective: The purpose of this study was to describe the prevalence and predictors of physical activity in women with polycystic ovary syndrome (PCOS) and to explore the potential health benefits that are associated with physical activity in this population.

Study Design: This was a cross-sectional assessment of 150 women with PCOS. Active women (those who met Department of Health and Human Services [DHHS] guidelines for exercise) were compared with inactive women with regards to demographic and psychosocial variables and health characteristics.

Results: Fifty-nine percent (88/150 women) met the DHHS guidelines for physical activity. Active women were more likely than inactive women to be nulliparous (64.1% vs 40.0%; P = .04) and white (71.6% vs 42.6%; P = .0004). Inactive women were more likely to have mild depression (adjusted odds ratio, 2.2; 95% confidence interval, 1.01-4.79; P = .048).

Conclusion: Women with PCOS who met the DHHS guidelines for physical activity were more likely to enjoy a variety of health benefits. Our findings identify several groups that are at risk for inadequate physical activity.
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http://dx.doi.org/10.1016/j.ajog.2010.12.006DOI Listing
April 2011
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