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Lee J, Akbas T, Sulzer J. Hip and Knee Joint Kinematics Predict Quadriceps Hyperreflexia in People with Post-stroke Stiff-Knee Gait. Ann Biomed Eng 2023; 51:1965-1974. [PMID: 37133540 PMCID: PMC11003447 DOI: 10.1007/s10439-023-03217-x] [Citation(s) in RCA: 0] [Impact Index Per Article: 0] [Reference Citation Analysis] [What about the content of this article? (0)] [Affiliation(s)] [Abstract] [Key Words] [MESH Headings] [Grants] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 11/11/2022] [Accepted: 04/20/2023] [Indexed: 05/04/2023]
Abstract
Wearable assistive technology for the lower extremities has shown great promise towards improving gait function in people with neuromuscular injuries. But common secondary impairments, such as hypersensitive stretch reflexes or hyperreflexia, have been often neglected. Incorporation of biomechanics into the control loop could improve individualization and avoid hyperreflexia. However, adding hyperreflexia prediction to the control loop would require expensive or complex measurement of muscle fiber characteristics. In this study, we explore a clinically accessible biomechanical predictor set that can accurately predict rectus femoris (RF) reaction after knee flexion assistance in pre-swing by a powered orthosis. We examined a total of 14 gait parameters based on gait kinematic, kinetic, and simulated muscle-tendon states from 8 post-stroke individuals with Stiff-Knee gait (SKG) wearing a knee exoskeleton robot. We independently performed both parametric and non-parametric variable selection approaches using machine learning regression techniques. Both models revealed the same four kinematic variables relevant to knee and hip joint motions were sufficient to effectively predict RF hyperreflexia. These results suggest that control of knee and hip kinematics may be a more practical method of incorporating quadriceps hyperreflexia into the exoskeleton control loop than the more complex acquisition of muscle fiber properties.
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Affiliation(s)
- Jeonghwan Lee
- Walker Department of Mechanical Engineering, University of Texas at Austin, Austin, TX, USA
| | | | - James Sulzer
- Department of Physical Medicine and Rehabilitation, MetroHealth Medical Center and Case Western Reserve University, Cleveland, OH, USA.
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Kim K, Akbas T, Lee R, Manella K, Sulzer J. Self-modulation of rectus femoris reflex excitability in humans. Sci Rep 2023; 13:8134. [PMID: 37208394 DOI: 10.1038/s41598-023-34709-4] [Citation(s) in RCA: 0] [Impact Index Per Article: 0] [Reference Citation Analysis] [What about the content of this article? (0)] [Affiliation(s)] [Abstract] [Grants] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 10/14/2022] [Accepted: 05/05/2023] [Indexed: 05/21/2023] Open
Abstract
Hyperreflexia is common after neurological injury such as stroke, yet clinical interventions have had mixed success. Our previous research has shown that hyperreflexia of the rectus femoris (RF) during pre-swing is closely associated with reduced swing phase knee flexion in those with post-stroke Stiff-Knee gait (SKG). Thus, reduction of RF hyperreflexia may improve walking function in those with post-stroke SKG. A non-pharmacological procedure for reducing hyperreflexia has emerged based on operant conditioning of H-reflex, an electrical analog of the spinal stretch reflex. It is currently unknown whether operant conditioning can be applied to the RF. This feasibility study trained 7 participants (5 neurologically intact, 2 post-stroke) to down-condition the RF H-reflex using visual feedback. We found an overall decrease in average RF H-reflex amplitude among all 7 participants (44% drop, p < 0.001, paired t-test), of which the post-stroke individuals contributed (49% drop). We observed a generalized training effect across quadriceps muscles. Post-stroke individuals exhibited improvements in peak knee-flexion velocity, reflex excitability during walking, and clinical measures of spasticity. These outcomes provide promising initial results that operant RF H-reflex conditioning is feasible, encouraging expansion to post-stroke individuals. This procedure could provide a targeted alternative in spasticity management.
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Affiliation(s)
| | | | - Robert Lee
- St. David's Medical Center, Austin, TX, USA
| | | | - James Sulzer
- University of Texas at Austin, Austin, TX, USA.
- MetroHealth Hospital and Case Western Reserve University, Cleveland, OH, USA.
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Schmitz DG, Nuckols RW, Lee S, Akbas T, Swaminathan K, Walsh CJ, Thelen DG. Modulation of Achilles tendon force with load carriage and exosuit assistance. Sci Robot 2022; 7:eabq1514. [DOI: 10.1126/scirobotics.abq1514] [Citation(s) in RCA: 0] [Impact Index Per Article: 0] [Reference Citation Analysis] [What about the content of this article? (0)] [Affiliation(s)] [Abstract] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 11/02/2022]
Abstract
Exosuits have the potential to assist locomotion in both healthy and pathological populations, but the effect of exosuit assistance on the underlying muscle-tendon tissue loading is not yet understood. In this study, we used shear wave tensiometers to characterize the modulation of Achilles tendon force with load carriage and exosuit assistance at the ankle. When walking (1.25 m/s) unassisted on a treadmill with load carriage weights of 15 and 30% of body weight, peak Achilles tendon force increased by 11 and 23%, respectively. Ankle exosuit assistance significantly reduced peak Achilles tendon force relative to unassisted, although the magnitude of change was variable across participants. Peak Achilles tendon force was significantly correlated with peak ankle torque for unassisted walking across load carriage conditions. However, when ankle plantarflexor assistance was applied, the relationship between peak tendon force and peak biological ankle torque was no longer significant. An outdoor pilot study was conducted in which a wearable shear wave tensiometer was used to measure Achilles tendon wave speed and compare across an array of assistance loading profiles. Reductions in tendon loading varied depending on the profile, highlighting the importance of in vivo measurements of muscle and tendon forces when studying and optimizing exoskeletons and exosuits.
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Affiliation(s)
- Dylan G. Schmitz
- Department of Mechanical Engineering, University of Wisconsin-Madison, Madison, WI, USA
| | - Richard W. Nuckols
- John A. Paulson School of Engineering and Applied Sciences, Harvard University, Cambridge, MA, USA
| | - Sangjun Lee
- John A. Paulson School of Engineering and Applied Sciences, Harvard University, Cambridge, MA, USA
| | - Tunc Akbas
- John A. Paulson School of Engineering and Applied Sciences, Harvard University, Cambridge, MA, USA
| | - Krithika Swaminathan
- John A. Paulson School of Engineering and Applied Sciences, Harvard University, Cambridge, MA, USA
| | - Conor J. Walsh
- John A. Paulson School of Engineering and Applied Sciences, Harvard University, Cambridge, MA, USA
| | - Darryl G. Thelen
- Department of Mechanical Engineering, University of Wisconsin-Madison, Madison, WI, USA
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Akbas T, Kim K, Doyle K, Manella K, Lee R, Spicer P, Knikou M, Sulzer J. Rectus femoris hyperreflexia contributes to Stiff-Knee gait after stroke. J Neuroeng Rehabil 2020; 17:117. [PMID: 32843057 PMCID: PMC7448457 DOI: 10.1186/s12984-020-00724-z] [Citation(s) in RCA: 17] [Impact Index Per Article: 4.3] [Reference Citation Analysis] [What about the content of this article? (0)] [Affiliation(s)] [Abstract] [Key Words] [Track Full Text] [Download PDF] [Figures] [Journal Information] [Subscribe] [Scholar Register] [Received: 10/17/2019] [Accepted: 07/06/2020] [Indexed: 11/17/2022] Open
Abstract
Background Stiff-Knee gait (SKG) after stroke is often accompanied by decreased knee flexion angle during the swing phase. The decreased knee flexion has been hypothesized to originate from excessive quadriceps activation. However, it is unclear whether hyperreflexia plays a role in this activation. The goal of this study was to establish the relationship between quadriceps hyperreflexia and knee flexion angle during walking in post-stroke SKG. Methods The rectus femoris (RF) H-reflex was recorded in 10 participants with post-stroke SKG and 10 healthy controls during standing and walking at the pre-swing phase. In order to attribute the pathological neuromodulation to quadriceps muscle hyperreflexia and activation, healthy individuals voluntarily increased quadriceps activity using electromyographic (EMG) feedback during standing and pre-swing upon RF H-reflex elicitation. Results We observed a negative correlation (R = − 0.92, p = 0.001) between knee flexion angle and RF H-reflex amplitude in post-stroke SKG. In contrast, H-reflex amplitude in healthy individuals in presence (R = 0.47, p = 0.23) or absence (R = − 0.17, p = 0.46) of increased RF muscle activity was not correlated with knee flexion angle. We observed a body position-dependent RF H-reflex modulation between standing and walking in healthy individuals with voluntarily increased RF activity (d = 2.86, p = 0.007), but such modulation was absent post-stroke (d = 0.73, p = 0.296). Conclusions RF reflex modulation is impaired in post-stroke SKG. The strong correlation between RF hyperreflexia and knee flexion angle indicates a possible regulatory role of spinal reflex excitability in post-stroke SKG. Interventions targeting quadriceps hyperreflexia could help elucidate the causal role of hyperreflexia on knee joint function in post-stroke SKG.
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Affiliation(s)
- Tunc Akbas
- School of Engineering and Applied Sciences, Harvard University, Cambridge, MA, USA
| | - Kyoungsoon Kim
- Walker Department of Mechanical Engineering, The University of Texas at Austin, Austin, TX, USA
| | - Kathleen Doyle
- Walker Department of Mechanical Engineering, The University of Texas at Austin, Austin, TX, USA
| | - Kathleen Manella
- University of St. Augustine for Health Sciences, Austin, TX, USA
| | - Robert Lee
- St. David's Medical Center, Austin, TX, USA
| | - Patrick Spicer
- Seton Brain and Spine Institute, Ascension Texas, University of Texas at Austin, Austin, TX, USA
| | - Maria Knikou
- Graduate Center of the City University of New York and Physical Therapy Department, College of Staten Island, New York, NY, USA
| | - James Sulzer
- Walker Department of Mechanical Engineering, The University of Texas at Austin, Austin, TX, USA.
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Park EJ, Akbas T, Eckert-Erdheim A, Sloot LH, Nuckols RW, Orzel D, Schumm L, Ellis TD, Awad LN, Walsh CJ. A hinge-free, non-restrictive, lightweight tethered exosuit for knee extension assistance during walking. ACTA ACUST UNITED AC 2020; 2:165-175. [PMID: 33748694 DOI: 10.1109/tmrb.2020.2989321] [Citation(s) in RCA: 31] [Impact Index Per Article: 7.8] [Reference Citation Analysis] [What about the content of this article? (0)] [Affiliation(s)] [Abstract] [Key Words] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 11/10/2022]
Abstract
In individuals with motor impairments such as those post-stroke or with cerebral palsy, the function of the knee extensors may be affected during walking, resulting in decreased mobility. We have designed a lightweight, hinge-free wearable robot combining soft textile exosuit components with integrated rigid components, which assists knee extension when needed but is otherwise highly transparent to the wearer. The exosuit can apply a wide range of assistance profiles using a flexible multi-point reference trajectory generator. Additionally, we implemented a controller safety limit to address the risk of hyperextension stemming from the hinge-free design. The exosuit was evaluated on six healthy participants walking uphill and downhill on a treadmill at a 10° slope with a set of joint power-inspired assistance profiles. A comparison of sagittal plane joint angles between no exosuit and exosuit unpowered conditions validated the device transparency. With positive power assistance, we observed reduction in average positive knee biological power during uphill walking (left: 17.5 ± 3.21%, p = 0.005; right: 23.2 ± 3.54%, p = 0.008). These initial findings show promise for the assistive capability of the device and its potential to improve the quality of gait and increase mobility in clinical populations.
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Affiliation(s)
- Evelyn J Park
- School of Engineering and Applied Sciences and the Wyss Institute for Biologically Inspired Engineering, Harvard University, Cambridge, MA 02138 USA
| | - Tunc Akbas
- School of Engineering and Applied Sciences and the Wyss Institute for Biologically Inspired Engineering, Harvard University, Cambridge, MA 02138 USA
| | - Asa Eckert-Erdheim
- School of Engineering and Applied Sciences and the Wyss Institute for Biologically Inspired Engineering, Harvard University, Cambridge, MA 02138 USA
| | - Lizeth H Sloot
- Institute for Computer Engineering (ZITI) at Heidelberg University, Heidelberg, Germany
| | - Richard W Nuckols
- School of Engineering and Applied Sciences and the Wyss Institute for Biologically Inspired Engineering, Harvard University, Cambridge, MA 02138 USA
| | - Dorothy Orzel
- School of Engineering and Applied Sciences and the Wyss Institute for Biologically Inspired Engineering, Harvard University, Cambridge, MA 02138 USA
| | - Lexine Schumm
- School of Engineering and Applied Sciences and the Wyss Institute for Biologically Inspired Engineering, Harvard University, Cambridge, MA 02138 USA
| | - Terry D Ellis
- Department of Physical Therapy & Athletic Training, Sargent College, Boston University, Boston, MA 02215 USA
| | - Louis N Awad
- Department of Physical Therapy & Athletic Training, Sargent College, Boston University, Boston, MA 02215 USA
| | - Conor J Walsh
- School of Engineering and Applied Sciences and the Wyss Institute for Biologically Inspired Engineering, Harvard University, Cambridge, MA 02138 USA
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Abstract
Assistive technology for the lower extremities has shown great promise towards improving gait function in people following neuromuscular injuries. However, our previous work assisting knee flexion torque in post-stroke Stiff-Knee gait found that augmenting strength can induce secondary complications such as spasticity due to stretching of the rectus femoris. In this work we explore whether we could have obtained improved knee flexion but avoided a spastic response by simulating combinations of hip and knee flexion torques using musculoskeletal modeling and simulation. We explore previously collected data on a case-by-case basis to determine individual-specific quadriceps reflex thresholds based on estimated rectus femoris muscle fiber stretch velocities. We then implemented a forward simulation framework to identify the subject-specific hip-knee assistance prescription to improve knee range of motion without initiating a spastic response. The obtained subject-specific assistive prescription informs the development of new gait assistance strategies for post-stroke gait and could be extended to other neuromuscular gait impairments.
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Lee J, Shin SY, Ghorpade G, Akbas T, Sulzer J. Sensitivity comparison of inertial to optical motion capture during gait: implications for tracking recovery. IEEE Int Conf Rehabil Robot 2019; 2019:139-144. [PMID: 31374620 DOI: 10.1109/icorr.2019.8779411] [Citation(s) in RCA: 11] [Impact Index Per Article: 2.2] [Reference Citation Analysis] [What about the content of this article? (0)] [Abstract] [MESH Headings] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 11/10/2022]
Abstract
Wearable sensors provide a foundation for development of wearable robotic technology to be used in clinical applications. Inertial motion capture (IMC) has emerged as a viable alternative to more cumbersome, non-portable optical methods. Previous work has validated the accuracy of IMC for gait compared to optical motion capture (OMC). However, it is unclear how well IMC can measure the small changes in gait function needed to gauge recovery. In this study, we evaluate the sensitivity of IMC compared to OMC to small changes in gait on a cohort of unimpaired individuals during treadmill walking. Eight individuals walked on a split-belt treadmill in three-minute trials with five randomized conditions: right belt speed decrementing at 0.05 m/s from 1.0 m/s, all with left belt held at 1.0 m/s, simulating recovery of hemiparetic gait. We extracted the root mean square deviation (RMSD) of joint kinematics between limbs and within the limb with modulated gait speed as the main outcome measure. We used linear mixed models to identify differences in sensitivity to changes in gait asymmetry and gait speed. Based on these models, we estimated the minimal detectible interval in gait parameters. We found that IMC was capable of measuring a difference in gait speed of 0.08 m/s, roughly the equivalent of two weeks recovery progress. Statistically we could not conclude a difference of sensitivity between IMC and OMC, although there is a strong trend that IMC is more sensitive to changes in gait. We conclude that IMC is a valid tool to measure progress in gait kinematics over the course of recovery.
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Akbas T, Neptune RR, Sulzer J. Neuromusculoskeletal Simulation Reveals Abnormal Rectus Femoris-Gluteus Medius Coupling in Post-stroke Gait. Front Neurol 2019; 10:301. [PMID: 31001189 PMCID: PMC6454148 DOI: 10.3389/fneur.2019.00301] [Citation(s) in RCA: 8] [Impact Index Per Article: 1.6] [Reference Citation Analysis] [What about the content of this article? (0)] [Affiliation(s)] [Abstract] [Key Words] [Grants] [Track Full Text] [Download PDF] [Figures] [Journal Information] [Subscribe] [Scholar Register] [Received: 01/08/2019] [Accepted: 03/11/2019] [Indexed: 11/13/2022] Open
Abstract
Post-stroke gait is often accompanied by muscle impairments that result in adaptations such as hip circumduction to compensate for lack of knee flexion. Our previous work robotically enhanced knee flexion in individuals post-stroke with Stiff-Knee Gait (SKG), however, this resulted in greater circumduction, suggesting the existence of abnormal coordination in SKG. The purpose of this work is to investigate two possible mechanisms of the abnormal coordination: (1) a reflex coupling between stretched quadriceps and abductors, and (2) a coupling between volitionally activated knee flexors and abductors. We used previously collected kinematic, kinetic and EMG measures from nine participants with chronic stroke and five healthy controls during walking with and without the applied knee flexion torque perturbations in the pre-swing phase of gait in the neuromusculoskeletal simulation. The measured muscle activity was supplemented by simulated muscle activations to estimate the muscle states of the quadriceps, hamstrings and hip abductors. We used linear mixed models to investigate two hypotheses: (H1) association between quadriceps and abductor activation during an involuntary period (reflex latency) following the perturbation and (H2) association between hamstrings and abductor activation after the perturbation was removed. We observed significantly higher rectus femoris (RF) activation in stroke participants compared to healthy controls within the involuntary response period following the perturbation based on both measured (H1, p < 0.001) and simulated (H1, p = 0.022) activity. Simulated RF and gluteus medius (GMed) activations were correlated only in those with SKG, which was significantly higher compared to healthy controls (H1, p = 0.030). There was no evidence of synergistic coupling between any combination of hamstrings and hip abductors (H2, p > 0.05) when the perturbation was removed. The RF-GMed coupling suggests an underlying abnormal coordination pattern in post-stroke SKG, likely reflexive in origin. These results challenge earlier assumptions that hip circumduction in stroke is simply a kinematic adaptation due to reduced toe clearance. Instead, abnormal coordination may underlie circumduction, illustrating the deleterious role of abnormal coordination in post-stroke gait.
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Affiliation(s)
| | | | - James Sulzer
- Walker Department of Mechanical Engineering, University of Texas at Austin, Austin, TX, United States
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Akbas T, Prajapati S, Ziemnicki D, Tamma P, Gross S, Sulzer J. Hip circumduction is not a compensation for reduced knee flexion angle during gait. J Biomech 2019; 87:150-156. [PMID: 30876735 DOI: 10.1016/j.jbiomech.2019.02.026] [Citation(s) in RCA: 13] [Impact Index Per Article: 2.6] [Reference Citation Analysis] [What about the content of this article? (0)] [Affiliation(s)] [Abstract] [Key Words] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 08/24/2018] [Revised: 02/28/2019] [Accepted: 02/28/2019] [Indexed: 11/29/2022]
Abstract
It has long been held that hip abduction compensates for reduced swing-phase knee flexion angle, especially in those after stroke. However, there are other compensatory motions such as pelvic obliquity (hip hiking) that could also be used to facilitate foot clearance with greater energy efficiency. Our previous work suggested that hip abduction may not be a compensation for reduced knee flexion after stroke. Previous study applied robotic knee flexion assistance in people with post-stroke Stiff-Knee Gait (SKG) during pre-swing, finding increased abduction despite improved knee flexion and toe clearance. Thus, our hypothesis was that hip abduction is not a compensation for reduced knee flexion. We simulated the kinematics of post-stroke SKG on unimpaired individuals with three factors: a knee orthosis to reduce knee flexion, an ankle-foot orthosis commonly worn by those post-stroke, and matching gait speeds. We compared spatiotemporal measures and kinematics between experimental factors within healthy controls and with a previously recorded cohort of people with post-stroke SKG. We focused on frontal plane motions of hip and pelvis as possible compensatory mechanisms. We observed that regardless of gait speed, knee flexion restriction increased pelvic obliquity (2.8°, p < 0.01) compared to unrestricted walking (1.5°, p < 0.01), but similar to post-stroke SKG (3.4°). However, those with post-stroke SKG had greater hip abduction (8.2°) compared to unimpaired individuals with restricted knee flexion (4.2°, p < 0.05). These results show that pelvic obliquity, not hip abduction, compensates for reduced knee flexion angle. Thus, other factors, possibly neural, facilitate exaggerated hip abduction observed in post-stroke SKG.
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Affiliation(s)
- Tunc Akbas
- Department of Mechanical Engineering, University of Texas at Austin, United States.
| | - Sunil Prajapati
- Department of Mechanical Engineering, University of Texas at Austin, United States
| | - David Ziemnicki
- Department of Mechanical Engineering, University of Texas at Austin, United States
| | - Poornima Tamma
- Department of Mechanical Engineering, University of Texas at Austin, United States
| | - Sarah Gross
- Department of Mechanical Engineering, University of Texas at Austin, United States
| | - James Sulzer
- Department of Mechanical Engineering, University of Texas at Austin, United States
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Ugurluer G, Akbas T, Arpaci T, Ozcan N, Serin M. Bone Complications After Pelvic Radiation Therapy: Evaluation With MRI. Int J Radiat Oncol Biol Phys 2014. [DOI: 10.1016/j.ijrobp.2014.05.1481] [Citation(s) in RCA: 0] [Impact Index Per Article: 0] [Reference Citation Analysis] [What about the content of this article? (0)] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 11/24/2022]
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Abstract
Copyright 2011 Wiley-Liss, Inc., A Wiley CompanyThis article is being made freely available through PubMed Central as part of the COVID-19 public health emergency response. It can be used for unrestricted research re-use and analysis in any form or by any means with acknowledgement of the original source, for the duration of the public health emergency. Omics technologies include genomics, transcriptomics, proteomics, metabolomics, and immunomics. These technologies have been used in vaccine research, which can be summarized using the term “vaccinomics.” These omics technologies combined with advanced bioinformatics analysis form the core of “systems vaccinology.” Omics technologies provide powerful methods in vaccine target identification. The genomics‐based reverse vaccinology starts with predicting vaccine protein candidates through in silico bioinformatics analysis of genome sequences. The VIOLIN Vaxign vaccine design program (http://www.violinet.org/vaxign) is the first web‐based vaccine target prediction software based on the reverse vaccinology strategy. Systematic transcriptomics and proteomics analyses facilitate rational vaccine target identification by detesting genome‐wide gene expression profiles. Immunomics is the study of the set of antigens recognized by host immune systems and has also been used for efficient vaccine target prediction. With the large amount of omics data available, it is necessary to integrate various vaccine data using ontologies, including the Gene Ontology (GO) and Vaccine Ontology (VO), for more efficient vaccine target prediction and assessment. All these omics technologies combined with advanced bioinformatics analysis methods for a systems biology‐based vaccine target prediction strategy. This article reviews the various omics technologies and how they can be used in vaccine target identification.
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Affiliation(s)
- T Arpaci
- Department of Radiology, Acibadem Adana Hospital, Adana, Turkey.
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Akbas T, Ugurluer G, Arpaci T. Solitary sternal metastasis of nasopharyngeal carcinoma: a case report. Eur Rev Med Pharmacol Sci 2012; 16:1947-1950. [PMID: 23242721] [Citation(s) in RCA: 0] [Impact Index Per Article: 0] [Reference Citation Analysis] [What about the content of this article? (0)] [Affiliation(s)] [Abstract] [MESH Headings] [Subscribe] [Scholar Register] [Indexed: 06/01/2023]
Abstract
Solitary sternal metastasis of nasopharyngeal carcinoma (NPC) is rare. At the time of diagnosis, distant metastases are found in about 5 to 7% of NPC patients. We report a case of isolated sternal metastasis of nasopharyngeal carcinoma in a 23 year-old man.
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Affiliation(s)
- T Akbas
- Department of Radiology, Acibadem University, Istanbul, Turkey.
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Akbas T, Duman D, Tahan V, Barghi I, Tözün N. Aorto-enteric fistula: a dilemma for the endoscopist as a rare cause of gastro-intestinal bleeding. Acta Chir Belg 2009; 109:541-3. [PMID: 19803276 DOI: 10.1080/00015458.2009.11680481] [Citation(s) in RCA: 3] [Impact Index Per Article: 0.2] [Reference Citation Analysis] [What about the content of this article? (0)] [Abstract] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 10/21/2022]
Abstract
A 78-year-old man with a history of aorta-femoral graft operation was admitted to the hospital with symptoms of syncope, melena and haematemesis. He reported several episodes of melena during the previous year for which he underwent repeated gastro-intestinal endoscopic examinations, which were unable to show the site of the gastro-intestinal bleeding. The third upper gastro-intestinal endoscopic examination disclosed a yellowish ulcerative lesion with irregular borders in the third part of the duodenum, which was considered to be a fistula, between the aorta and the duodenum. The patient underwent an explorative operation that revealed an intact aortic graft, firmly adherent to the duodenal wall, and the duodenum that was eroded in the third portion. The duodenum was transected and a duodenoduodenostomy was performed. Although re-bleeding did not occur, the patient died of sepsis eight days after the operation. Aorto-enteric fistulae can be missed due to the common practice of limiting the endoscopic examination to the second part of the duodenum and not considering them in the differential diagnosis of gastro-intestinal bleeding because of their rarity. Possibly, a number of prior endoscopic examinations may be inconclusive until a correct diagnosis is reached in most of the cases.
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Akbas T, Beker ÜG, Güner FS, Erciyes AT, Yagci Y. Drying and semidrying oil macromonomers. III. Styrenation of sunflower and linseed oils. J Appl Polym Sci 2003. [DOI: 10.1002/app.11638] [Citation(s) in RCA: 32] [Impact Index Per Article: 1.5] [Reference Citation Analysis] [What about the content of this article? (0)] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 11/10/2022]
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