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Barnes-Wood M, McCloskey H, Connelly S, Gilchrist MD, Annaidh AN, Theobald PS. Investigation of Head Kinematics and Brain Strain Response During Soccer Heading Using a Custom-Fit Instrumented Mouthguard. Ann Biomed Eng 2024; 52:934-945. [PMID: 38243139 PMCID: PMC10940496 DOI: 10.1007/s10439-023-03430-8] [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: 07/26/2023] [Accepted: 12/21/2023] [Indexed: 01/21/2024]
Abstract
Association football, also known as soccer in some regions, is unique in encouraging its participants to intentionally use their head to gain a competitive advantage, including scoring a goal. Repetitive head impacts are now being increasingly linked to an inflated risk of developing long-term neurodegenerative disease. This study investigated the effect of heading passes from different distances, using head acceleration data and finite element modelling to estimate brain injury risk. Seven university-level participants wore a custom-fitted instrumented mouthguard to capture linear and angular acceleration-time data. They performed 10 headers within a laboratory environment, from a combination of short, medium, and long passes. Kinematic data was then used to calculate peak linear acceleration, peak angular velocity, and peak angular acceleration as well as two brain injury metrics: head injury criterion and rotational injury criterion. Six degrees of freedom acceleration-time data were also inputted into a widely accepted finite element brain model to estimate strain-response using mean peak strain and cumulative strain damage measure values. Five headers were considered to have a 25% concussion risk. Mean peak linear acceleration equalled 26 ± 7.9 g, mean peak angular velocity 7.20 ± 2.18 rad/s, mean peak angular acceleration 1730 ± 611 rad/s2, and 95th percentile mean peak strain 0.0962 ± 0.252. Some of these data were similar to brain injury metrics reported from American football, which supports the need for further investigation into soccer heading.
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Affiliation(s)
- M Barnes-Wood
- Cardiff School of Engineering, Cardiff University, The Parade, Cardiff, CF24 3AA, UK
- Charles Owen & Co, Croesfoel Industrial Park, Wrexham, LL14 4BJ, UK
| | - H McCloskey
- Cardiff School of Engineering, Cardiff University, The Parade, Cardiff, CF24 3AA, UK
- Charles Owen & Co, Croesfoel Industrial Park, Wrexham, LL14 4BJ, UK
| | - S Connelly
- Football Association of Wales (FIFA Medical Centre of Excellence), Hensol, Pontyclun, CF72 8JY, UK
| | - M D Gilchrist
- School of Mechanical and Materials Engineering, University College Dublin, Belfield, Dublin 4, Ireland
| | - A Ni Annaidh
- School of Mechanical and Materials Engineering, University College Dublin, Belfield, Dublin 4, Ireland
| | - P S Theobald
- Cardiff School of Engineering, Cardiff University, The Parade, Cardiff, CF24 3AA, UK.
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Jones M, Darwall D, Khalid G, Prabhu R, Kemp A, Arthurs OJ, Theobald P. Development and validation of a physical model to investigate the biomechanics of infant head impact. Forensic Sci Int 2017; 276:111-119. [PMID: 28525774 DOI: 10.1016/j.forsciint.2017.03.025] [Citation(s) in RCA: 8] [Impact Index Per Article: 1.1] [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: 08/17/2016] [Revised: 03/18/2017] [Accepted: 03/27/2017] [Indexed: 11/29/2022]
Abstract
Head injury in childhood is the single most common cause of death or permanent disability from injury. However, despite its frequency and significance, there is little understanding of the response of a child's head to injurious loading. This is a significant limitation when making early diagnoses, informing clinical and/or forensic management or injury prevention strategies. With respect to impact vulnerability, current understanding is predominantly based on a few post-mortem-human-surrogate (PMHS) experiments. Researchers, out of experimental necessity, typically derive acceleration data, currently an established measure for head impact vulnerability, by calculation. Impact force is divided by the head mass, to produce a "global approximation", a single-generalised head response acceleration value. A need exists for a new experimental methodology, which can provide specific regional or localised response data. A surrogate infant head, was created from high resolution computer tomography scans with properties closely matched to tissue response data and validated against PMHS head impact acceleration data. The skull was 3D-printed from co-polymer materials. The brain, represented as a lumped mass, comprised of an injected gelatin/water mix. High-Speed Digital-Image-Correlation optically measured linear and angular velocities and accelerations, strains and strain rates. The "global approximation" was challenged by comparison with regional and local acceleration data. During impacts, perpendicular (at 90°) to a surface, regional and local accelerations were up to three times greater than the concomitant "global" accelerations. Differential acceleration patterns were very sensitive to impact location. Suture and fontanelle regions demonstrated ten times more strain (103%/s) than bone, resulting in skull deformations similar in magnitude to those observed during child birth, but at much higher rates. Surprisingly, perpendicular impacts produced significantly greater rotational velocities and accelerations, which are closer to current published injury thresholds than expected, seemingly as a result of deformational changes to the complex skull geometry. The methodology has proven a significant new step in characterising and understanding infant head injury mechanics.
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Affiliation(s)
- M Jones
- Cardiff School of Engineering, Cardiff University, Cardiff, UK.
| | - D Darwall
- Cardiff School of Engineering, Cardiff University, Cardiff, UK
| | - G Khalid
- Cardiff School of Engineering, Cardiff University, Cardiff, UK
| | - R Prabhu
- Center for Advanced Vehicular Systems, Mississippi State University, Starkville, MS, USA
| | - A Kemp
- College of Biomedical and Life Sciences, School of Medicine, Cardiff University, Cardiff, UK
| | - Owen J Arthurs
- Great Ormond Street Hospital for Children NHS Foundation Trust, London, UK
| | - P Theobald
- Cardiff School of Engineering, Cardiff University, Cardiff, UK
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3
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Rodger MP, Theobald P, Giddins G. Vein grafts to augment flexor tendon repairs: a biomechanical study on strength and gap resistance. J Hand Surg Eur Vol 2015; 40:695-9. [PMID: 25541551 DOI: 10.1177/1753193414564902] [Citation(s) in RCA: 6] [Impact Index Per Article: 0.7] [Reference Citation Analysis] [What about the content of this article? (0)] [Affiliation(s)] [Abstract] [Key Words] [Track Full Text] [Journal Information] [Submit a Manuscript] [Subscribe] [Scholar Register] [Received: 04/15/2014] [Accepted: 11/22/2014] [Indexed: 02/03/2023]
Abstract
The ultimate tensile repair strength and gap formation of the pig extensor tendons repaired with a standard 4-strand Savage with epitendinous suture repair, was compared with a new technique of adding a vein sleeve. Force and displacement data were recorded, and video images during linear cyclic loading up to failure. At 35 N, video-graphic observation detected significantly smaller gap lengths in the standard and vein repair specimens compared with standard repair specimens (p = 0.047). The incidence of 3 mm gaps between the repaired tendon ends in the standard repair group was 20 %, but no 3 mm gaps were seen in the standard and vein specimens. The addition of a vein sleeve increased the ultimate tensile strength of the standard repair from 50.4 N (4.5) to 55.4 N (4.5); this was statistically significant (p = 0.03). This study demonstrated that the addition of a vein graft prevented gap formation and increased ultimate tensile strength of tendon repair.
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Affiliation(s)
- M P Rodger
- School of Engineering, Cardiff University, Cardiff, UK
| | - P Theobald
- School of Engineering, Cardiff University, Cardiff, UK
| | - G Giddins
- Department of Mechanical Engineering, University of Bath, Bath, UK
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Williams JM, Theobald PS, Jones MD. Infant cervical range of motion in the sagittal plane. International Journal of Therapy and Rehabilitation 2014. [DOI: 10.12968/ijtr.2014.21.sup7.s6] [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: 11/11/2022]
Abstract
Background: Data pertaining to infant sagittal cervical range of motion (CROM) is lacking. Previous studies have either quantified motions other than sagittal or quantified sagittal range of motion in children >3 years old. Data capture in infants is complex and novel methods are required to overcome previous limitations. Such data is invaluable to inform paediatric injury models, such as those for shaken baby syndrome and automotive safety. Methods: Nine infants were recruited from a local group of parents (mean age=406 days, SD=19). Sagittal range-of-motion was measured using two miniature accelerometers (THETAmetrix), which provide orientation angle with respect to gravity. One sensor was placed on the forehead and one over the T2–3 spinous process. Sagittal range of motion was determined by subtracting the tilt angle of thorax sensor from that of the forehead and then summing the total sagittal movement cycle to yield resultant cervical range of motion. Infants were placed in their usual highchair and encouraged to move their head into flexion and extension by a parent focussing their attention on a favourite toy. At the point of maximal motion, the lead researcher applied gentle overpressure to ensure full range was achieved with parental consent. Once one full cycle of sagittal motion was achieved, data collection was terminated. Results: Overpressure was not possible in two infants, therefore, their data was omitted. The mean peak sagittal range of motion was 115° (SD=12) with a 95% CI=106–124°. Conclusions: The described methods were successful in measuring sagittal CROM in infants and could be used to determine range of motion in even younger infants. The data produced is in agreement with previous reports on older children; however, this method overcomes limitations of other data capture methods. Implications: The results provide the first estimate of infant CROM. These data can serve as reference for models of musculoskeletal and neurological injury, including those for shaken baby syndrome and automotive safety.
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Affiliation(s)
- JM Williams
- School of Health and Social Care, Bournemouth University
| | - PS Theobald
- School of Health and Social Care, Bournemouth University
| | - MD Jones
- School of Health and Social Care, Bournemouth University
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Alqhtani RS, Williams JM, Jones MD, Theobald PS. Hip and lumbar motion: Is there a correlation between flexion and functional tasks? International Journal of Therapy and Rehabilitation 2014. [DOI: 10.12968/ijtr.2014.21.sup7.s7] [Citation(s) in RCA: 1] [Impact Index Per Article: 0.1] [Reference Citation Analysis] [What about the content of this article? (0)] [Affiliation(s)] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 11/11/2022]
Affiliation(s)
- RS Alqhtani
- School of Health and Social Care, Bournemouth University
| | - JM Williams
- School of Health and Social Care, Bournemouth University
| | - MD Jones
- School of Health and Social Care, Bournemouth University
| | - PS Theobald
- School of Health and Social Care, Bournemouth University
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Alqhtani RS, Jones MD, Theobald PS, Williams JM. The reliability of novel multiregional spinal motion measurement device. International Journal of Therapy and Rehabilitation 2014. [DOI: 10.12968/ijtr.2014.21.sup7.s6a] [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: 11/11/2022]
Abstract
Background: Current spinal range of motion (ROM) measurement methods have limitations ranging from the amount of detail obtained to environmental costs and complexity. In particular, limited regional spinal motion is obtained using the current methods. However, a new portable ‘string’ of accelerometers is proposed to overcome these limitations. Objectives: This study seeks to determine the reliability of this sensor string in measuring three-dimensional spinal ROM and to investigate the relative motions across six different regions. Methods: Two procedures were undertaken on 18 healthy participants. Protocol one: two sensors were placed on the forehead and T1 to measure cervical ROM; and protocol two: six sensors were placed on the spinous processes of T1, T4, T8, T12, L3 and S1 to measure thoraco-lumbar regional ROM. Results: The ICC values for all regions were found to be high, ranging from ICC=0.88–0.99 for all movements and regions of the spine, demonstrating that the proposed methods were highly reliable for repeated measures. The standard error of the means (SEMs) were small, ranging from 0.7–5.2°. The flexion/extension motion demonstrated a mean SEM of 1.9° and 1.1° for lateral bending motions. Slightly larger SEMs were observed for rotation, especially for the upper thoracic (UT) and mid thoracic (MT) region with an overall mean SEM of 3.1°. Minimum detectable change (MDC) values ranged from 1.9–14.4°. The flexion/extension motion demonstrated a mean MDC of 5.2° with 3.1° for lateral bending motions. Slightly larger MDCs were observed for rotation (mean MDC=8.4°), especially for the UT and MT region. Implications: This method was able to quantify the relative contribution of differing regions to the overall motion. The method described represents a reliable method of assessing spinal ROM across multiple spinal regions.
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Affiliation(s)
- RS Alqhtani
- Institute of Medical Engineering and Medical Physics, Cardiff School of Engineering, Cardiff University
| | - MD Jones
- Institute of Medical Engineering and Medical Physics, Cardiff School of Engineering, Cardiff University
| | - PS Theobald
- Institute of Medical Engineering and Medical Physics, Cardiff School of Engineering, Cardiff University
| | - JM Williams
- Institute of Medical Engineering and Medical Physics, Cardiff School of Engineering, Cardiff University
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Abstract
When considering cases of infant head injury as a result of a short fall, investigators often have to base their opinions on the potential severity of a head injury on a scene description and/or photographic evidence of the potential impact surfaces. While variation in the attenuation properties of typical domestic surfaces and underlying support structures have been reported in the literature, this study investigates whether there is a need to consider the nature and composition of specific potential impact floor surfaces/sites, within a scene, prior to providing an opinion about the likely head impact injury outcome. An instrumented headform was impacted within a suspected crime scene to determine whether different potential impact sites posed different risks of producing head injury. The impact acceleration-time waveform, for the headform, was shown to vary considerably across the floor. By applying recognized head impact injury risk measures (peak g and head injury criterion), it was illustrated that the risk of an infant sustaining a significant head injury could vary considerably, depending upon the exact point of impact with the floor. This study highlights the potential for variation in impact force across a scene and illustrates the need to consider surface composition at specific sites across the entire potential impact area, since the risk of head injury can vary significantly. Caution should therefore be exercised when expressing opinions based solely on verbal, written or photographic evidence of head impact surfaces, without due consideration of the specific area onto which a head might have impacted.
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Affiliation(s)
- M D Jones
- Institute of Medical Engineering and Medical Physics, Cardiff University, The Parade, Cardiff, Wales, UK.
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Thomas JMC, Beevers D, Dowson D, Jones MD, King P, Theobald PS. The Bio-Tribological Characteristics of Synthetic Tissue Grafts. Proc Inst Mech Eng H 2010; 225:141-8. [DOI: 10.1243/09544119jeim796] [Citation(s) in RCA: 5] [Impact Index Per Article: 0.4] [Reference Citation Analysis] [What about the content of this article? (0)] [Affiliation(s)] [Abstract] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 11/18/2022]
Abstract
The use of synthetic connective tissue grafts became popular in the mid-1980s, particularly for anterior cruciate ligament reconstruction; however, this trend was soon changed given the high failure rate due to abrasive wear. More than 20 years later, a vast range of grafts are available to the orthopaedic surgeon for augmenting connective tissue following rupture or tissue loss. While the biomechanical properties of these synthetic grafts become ever closer to the natural tissue, there have been no reports of their bio-tribological (i.e. bio-friction) characteristics. In this study, the bio-tribological performance of three clinically available synthetic tissue grafts, and natural tendon, was investigated. It was established that the natural tissue exhibits fluid-film lubrication characteristics and hence is highly efficient when sliding against opposing tissues. Conversely, all the synthetic tissues demonstrated boundary or mixed lubrication regimes, resulting in surface—surface contact, which will subsequently cause third body wear. The tribological performance of the synthetic tissue, however, appeared to be dependent on the macroscopic structure. This study indicates that there is a need for synthetic tissue designs to have improved frictional characteristics or to use a scaffold structure that encourages tissue in-growth. Such a development would optimize the bio-tribological properties of the synthetic tissue and thereby maximize longevity.
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Affiliation(s)
- J M C Thomas
- Department of Trauma and Orthopaedics, The Royal London Hospital, Whitechapel, London, UK
| | - D Beevers
- Xiros, Springfield House, Whitehouse Lane, Leeds, UK
| | - D Dowson
- Trauma Biomechanics Research Group, Institute of Medical Engineering and Medical Physics, Cardiff University, Cardiff, UK
| | - M D Jones
- Trauma Biomechanics Research Group, Institute of Medical Engineering and Medical Physics, Cardiff University, Cardiff, UK
| | - P King
- Trauma Biomechanics Research Group, Institute of Medical Engineering and Medical Physics, Cardiff University, Cardiff, UK
| | - P S Theobald
- Trauma Biomechanics Research Group, Institute of Medical Engineering and Medical Physics, Cardiff University, Cardiff, UK
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Theobald P, O'Doherty DM, Holt CA, Evans SL, Jones MD. Medical engineering at Cardiff University. Part 2: Postgraduate programmes of study. Proc Inst Mech Eng H 2009; 223:431-5. [PMID: 19499832 DOI: 10.1243/09544119jeim534] [Citation(s) in RCA: 4] [Impact Index Per Article: 0.3] [Reference Citation Analysis] [What about the content of this article? (0)] [Affiliation(s)] [Abstract] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 11/18/2022]
Abstract
The Medical Engineering team within the School of Engineering, Cardiff University, delivers two postgraduate programmes of study. Established over 10 years ago, the part-time MSc programmes in Orthopaedic Engineering and Clinical Engineering offer the opportunity of further study while remaining within full-time employment. Both programmes deliver 120 taught credits over two academic years via a series of residential weekends, with successful completion enabling the student to undertake and then defend a 60-credit research dissertation. Fulfilling a specific role on the career pathway for both student cohorts, the strength of each programme is indicated by the consistent number of applicants.
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Affiliation(s)
- P Theobald
- Institute of Medical Engineering and Medical Physics, Cardiff University, Cardiff, UK
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11
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Theobald P, Jones MD, Holt CA, Evans SL, O'Doherty DM. Medical engineering at Cardiff University. Part 1: Undergraduate programmes of study. Proc Inst Mech Eng H 2009; 223:425-30. [PMID: 19499831 DOI: 10.1243/09544119jeim533] [Citation(s) in RCA: 1] [Impact Index Per Article: 0.1] [Reference Citation Analysis] [What about the content of this article? (0)] [Affiliation(s)] [Abstract] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 11/18/2022]
Abstract
Cardiff University has offered a medical engineering undergraduate programme since 2001 and hence delivers one of the longest-running and most established medical engineering programmes within the UK. It currently offers BEng (Hons) and MEng (Hons) programmes that are both accredited by the Institution of Mechanical Engineers and include the option to undertake a year in industrial employment. The admissions policy ensures that the intake consists of a diverse range of students and is typically very successful in attracting female students. The programmes consist of six key academic threads which ensure that the content is both relevant and continuous, with all threads tailored to provide a patient-focused learning environment. Students initially learn core and fundamental principles in years 1 and 2, supported by a range of laboratories and practical experimentation. The latter years then encourage the students to corroborate and apply this knowledge, including involvement in a range of project-based learning exercises. The programme is delivered by a core of experienced academic medical engineers, with support from other engineering colleagues, as well as colleagues from the School of Biosciences, the School of Medicine, and the National Health Service. Thus, the programme delivers a wide range of modules which guarantee that graduating students have a thorough understanding of all possible career options. These two factors are significant in making it possible for students to follow their chosen career path upon graduation.
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Affiliation(s)
- P Theobald
- Institute of Medical Engineering and Medical Physics, Cardiff University, Queen's Building, The Parade, Cardiff CF24 3AA, UK
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Theobald P, Byrne C, Oldfield SF, Dowson D, Benjamin M, Dent C, Pugh N, Nokes LDM. Lubrication regime of the contact between fat and bone in bovine tissue. Proc Inst Mech Eng H 2007; 221:351-6. [PMID: 17605392 DOI: 10.1243/09544119jeim176] [Citation(s) in RCA: 10] [Impact Index Per Article: 0.6] [Reference Citation Analysis] [What about the content of this article? (0)] [Affiliation(s)] [Abstract] [MESH Headings] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 11/18/2022]
Abstract
Fat pads are masses of encapsulated adipose tissue located throughout the human body. Whilst a number of studies describe these soft tissues anatomically little is known about their biomechanics, and surgeons may excise them arthroscopically if they hinder visual inspection of the joint or bursa. By measuring the coefficient of friction between, and performing Sommerfeld analysis of, the surfaces approximating the in vivo conjuncture, this contact has been shown to have a coefficient of friction of the order of 0.01. The system appears to be lubricated hydrodynamically, thus possibly promoting low levels of wear. It is suggested that one of the functions of fat pads associated with subtendinous bursae and synovial joints is to generate a hydrodynamic lubricating layer between the opposing surfaces.
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Affiliation(s)
- P Theobald
- Institute of Medical Engineering and Medical Physics, Cardiff University, Cardiff, UK.
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Theobald P, Bydder G, Dent C, Nokes L, Pugh N, Benjamin M. The functional anatomy of Kager's fat pad in relation to retrocalcaneal problems and other hindfoot disorders. J Anat 2006; 208:91-7. [PMID: 16420382 PMCID: PMC2100176 DOI: 10.1111/j.1469-7580.2006.00510.x] [Citation(s) in RCA: 73] [Impact Index Per Article: 4.1] [Reference Citation Analysis] [What about the content of this article? (0)] [Affiliation(s)] [Abstract] [MESH Headings] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 12/17/2022] Open
Abstract
Kager's fat pad is a mass of adipose tissue occupying Kager's triangle. By means of a combined magnetic resonance imaging, ultrasound, gross anatomical and histological study, we show that it has three regions that are closely related to the sides of the triangle. Thus, it has parts related to the Achilles and flexor hallucis longus (FHL) tendons and a wedge of fat adjacent to the calcaneus. The calcaneal wedge moves into the bursa during plantarflexion, as a consequence of both an upward displacement of the calcaneus relative to the wedge and a downward displacement of the wedge relative to the calcaneus. During dorsiflexion, the bursal wedge is retracted. The movements are promoted by the tapering shape of the bursal wedge and by its deep synovial infolds. Fibrous connections linking the fat to the Achilles tendon anchor and stabilize it proximally and thus contribute to the motility of its tip. We conclude that the three regions of Kager's fat pad have specialized functions: an FHL part which contributes to moving the bursal wedge during plantarflexion, an Achilles part which protects blood vessels entering this tendon, and a bursal wedge which we suggest minimizes pressure changes in the bursa. All three regions contribute to reducing the risk of tendon kinking and each may be implicated in heel pain syndromes.
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Affiliation(s)
- P Theobald
- Institute of Medical Engineering and Medical Physics, Cardiff University, UK
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Abstract
A region of avascularity mid-way along the length of the Achilles tendon has long been associated with rupture. Whilst it is agreed that this region is the location most common to rupture, the exact vascular distribution appears unclear. Regions of avascularity identified within the tendon have included the origin and insertion, as well as the midsection. This review aims to analyse critically and summarise all previous studies of the vascularisation of the healthy human Achilles tendon, in order to determine the most likely region of avascularity and, thereby establish whether a relationship exists between vascularisation and rupture. Whilst no definitive conclusion was reached, it was concluded that the vascularisation does affect the tensile strength and so rupture vulnerability of the healthy Achilles tendon, although it is unlikely to be either the sole, or most significant, contributor. Other factors, such as thinning and twisting of the tendon at the midsection are mechanical influences that will increase the incidence of rupture by increasing the concentration of stress.
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Affiliation(s)
- P Theobald
- Research Office, Cardiff School of Engineering, Queens Building, The Parade, P.O. Box 925, Cardiff CF24 0YF, UK.
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Yan T, Theobald P, Jones BE. A conical piezoelectric transducer with integral sensor as a self-calibrating acoustic emission energy source. Ultrasonics 2004; 42:431-438. [PMID: 15047324 DOI: 10.1016/j.ultras.2003.12.039] [Citation(s) in RCA: 1] [Impact Index Per Article: 0.1] [Reference Citation Analysis] [What about the content of this article? (0)] [Affiliation(s)] [Abstract] [Track Full Text] [Subscribe] [Scholar Register] [Indexed: 05/24/2023]
Abstract
The experimental results of a conical piezoelectric transducer with integral backing sensor as a self-calibrating simulated acoustic emission (SAE) energy source are presented. It has been shown that there is a negative linear relationship between the energy of SAE signal detected by the backing sensor and the relative strength (signal energy) of SAE source in the structure detected by a reference sensor under different transducer-to-structure coupling efficiencies, with AC drives of the same wave packet, frequency and peak amplitude to excite the conical transducer as a SAE source at all the investigated frequencies over the frequency range of interest in AE measurements (nominally from 50 kHz to around 1 MHz). This should enable the relative strength of the SAE source in a structure to be determined using the SAE measurement from the backing sensor for the selected electrical inputs to the conical transducer, and hence to remove the concerns about inconsistent transducer-to-structure coupling affecting the relative strength of the SAE source for calibration.
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Affiliation(s)
- T Yan
- Brunel Centre for Manufacturing Metrology, Brunel University, Uxbridge, Middlesex UB8 3PH, UK
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16
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Gordon P, Theobald P. Migration and spatial development in the Republic of Mexico. J Dev Areas 2002; 15:239-50. [PMID: 12338657] [Citation(s) in RCA: 0] [Impact Index Per Article: 0] [Reference Citation Analysis] [What about the content of this article? (0)] [Key Words] [MESH Headings] [Subscribe] [Scholar Register] [Indexed: 02/26/2023]
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Cervini L, Theobald P, Corrigan A, Craig AG, Rivier C, Vale W, Rivier J. Corticotropin releasing factor (CRF) agonists with reduced amide bonds and Ser7 substitutions. J Med Chem 1999; 42:761-8. [PMID: 10052982 DOI: 10.1021/jm980607e] [Citation(s) in RCA: 12] [Impact Index Per Article: 0.5] [Reference Citation Analysis] [What about the content of this article? (0)] [Affiliation(s)] [Abstract] [MESH Headings] [Grants] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 11/28/2022]
Abstract
Strategies to generate competitive antagonists of bioactive peptides include several possible structural modifications such as the introduction of D-residues and of reduced amide bonds, the substitution of amino acid side chains, dimerization of fragments, and deletion of part of the sequence, among others. Whereas we have identified the two most likely residues responsible for receptor activation in corticotropin releasing factor (CRF) (Ser7 and Leu8)1 and generated potent antagonists by deleting residues 1-8,2,3 the question remained as to whether we could generate CRF antagonists with enhanced affinity after reduction of amide bonds at the N-terminus of CRF or through subtle alteration of those residues' side chains. Reduced amide bond replacements (psi[CH2NH]) between residues 6-9 in oCRF(5-41) (11, 12, 15) analogues consistently yielded potencies of <1% that of oCRF. Except for the 10psi11 and 12psi13 analogues 19 and 20, reduced amide bond replacements were generally well-tolerated in the longer hCRF(4-41) analogues, with the 7psi8-, 8psi9-, and 9psi10-modified peptides (13, 14, 18) yielding potencies that were 2-4 times that of hCRF. Although somewhat promising as agonists, they were, however, 3-7 times less potent than the parent [D-Pro4Nle21,38]-hCRF(4-41) (2). Since O-alkylation of Tyr3 in vasopressin yields an antagonist, and since Ser7 is one of the eight fully conserved residues in the CRF family (inclusive of sauvagine, urocortins, and urotensins) and likely to be critical for receptor binding, we synthesized cyclo(30-33)[Ser(OMe)7,D-Phe12,Nle21,Glu30,Lys33 ,Nle38]Ac-hCRF(7-41) (22), which was found to exhibit full efficacy and 40% of the potency of cyclo(30-33)[D-Phe12,Nle21,Glu30,Lys33, Nle38]Ac-hCRF(7-41) (5). Other substitutions at position 7 included aminoglycine (23, 24) and alkylated and/or acylated [alpha or alpha'-methyl (25-28), alpha'-formyl (29, 30), alpha'-formyl, alpha'-methyl (31), alpha'-acetyl (32), alpha'-acetyl, alpha'-methyl (33)], D- or L-aminoglycines. All analogues were active although less potent than the parent compound 2, and all elicited maximal ACTH response as compared to hCRF. The most potent analogue in this series (33) had the bulkiest side chain, Agl(Me, Ac), and was 60% and 80% as potent as the Ser7 analogue 5 and the Ala7 analogue 6, respectively. In conclusion, we found that neither reduction of the individual amide linkages between residues 6-11 and 12-13 nor introduction of a carbamide moiety in lieu of the side chain of Ser7 led to CRF antagonists.
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Affiliation(s)
- L Cervini
- The Clayton Foundation Laboratories for Peptide Biology, The Salk Institute for Biological Studies, 10010 N. Torrey Pines Road, La Jolla, California 92037, USA
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Rivier J, Porter J, Hoeger C, Theobald P, Craig AG, Dykert J, Corrigan A, Perrin M, Hook WA, Siraganian RP. Gonadotropin-releasing hormone antagonists with N omega-triazolylornithine, -lysine, or -p-aminophenylalanine residues at positions 5 and 6. J Med Chem 1992; 35:4270-8. [PMID: 1280300 DOI: 10.1021/jm00101a003] [Citation(s) in RCA: 46] [Impact Index Per Article: 1.4] [Reference Citation Analysis] [What about the content of this article? (0)] [Affiliation(s)] [Abstract] [MESH Headings] [Grants] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 12/26/2022]
Abstract
In order to be used as fertility regulators in humans, gonadotropin releasing hormone (GnRH) antagonists must be extremely potent and long acting and exhibit negligible side effects such as stimulating histamine release. To this aim, we have recently synthesized a series of analogues with the standard Ac-DNal1-DCpa2-DPal3 substitutions, where the N omega-amino function of ornithine, lysine, or p-aminophenylalanine (Aph) was converted to the aminotriazolyl (atz) derivatives at positions 5 and 6 with further modifications at positions 7 and 10. The analogues were tested for their ability to bind to pituitary cell membranes, to release histamine in a mast cell assay, to inhibit luteinizing hormone (LH) secretion by castrated male rats or cultured pituitary cells, and to interfere with the ovulation in intact female rats. While the subcutaneous (sc) injection of 50 micrograms of Azaline A (7, [Ac-DNal1,DCpa2,DPal3,Lys5(atz),DLys6++ +(atz),ILys8,DAla10]GnRH) dissolved in 0.2 mL of an aqueous media significantly inhibited LH release in the castrated male rat for 24 h, the same dose of Azaline B (11), [Ac-DNal1,DCpa2,DPal3,Aph5(atz),DAph6++ +(atz),ILys8,DAla10]GnRH, inhibited LH release for 72 h. A similar long duration of action was observed for Antide ([Ac-DNal1,DCpa2,DPal3,Lys5(Nic),DLys6(Nic ),ILys8,DAla10]GnRH) but not for Nal-Glu ([Ac-DNal1,DCpa2,DPal3,Arg5,4-(pmethoxybenzoy l)-D-2-Abu6,DAla10]GnRH). In the same paradigm, a 5-fold dilution of the peptide (50 micrograms in 1 mL) and the use of three injection sites rather than one resulted in significantly shorter duration of action for most of the peptides tested. This suggested that long duration of action might be the result of slow release from the injection site(s). In order to investigate this possibility, Nal-Glu and Azaline B were injected intravenously (i.v.) at three doses (10, 50, 250 micrograms) to castrated male rats. At all doses, both peptides significantly lowered LH levels for 8 h. By 24 h, Nal-Glu (250 micrograms) and Azaline B (50 and 250 micrograms) still measurably inhibited LH secretion. Finally, only Azaline B (250 micrograms) was still active at 48 h. These findings demonstrate that subtle structural modifications will yield peptides with different half-lives after iv administration. These findings led us to investigate the effects of other structural modifications on duration of action. We observed that systematic substitutions at positions 7 (NMeLeu) and 10 (Pro9-NHEt, and Gly-NH2) were found to be deleterious. Of interest was the observation that only the DAla10-NH2 substitution led to long duration of action and enzymatic stability under the conditions tested.(ABSTRACT TRUNCATED AT 400 WORDS)
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Affiliation(s)
- J Rivier
- Salk Institute for Biological Studies, La Jolla, California 92037
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Rivier JP, Theobald P, Hoeger C, Craig AG, Perrin M, Porter J, Corrigan A, Koerber S, Hagler A, Vale W, Rivier C. GnRH antagonists: A synopsis. Contraception 1992. [DOI: 10.1016/0010-7824(92)90014-k] [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: 10/26/2022]
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Theobald P, Porter J, Rivier C, Corrigan A, Hook W, Siraganian R, Perrin M, Vale W, Rivier J. Novel gonadotropin-releasing hormone antagonists: peptides incorporating modified N omega-cyanoguanidino moieties. J Med Chem 1991; 34:2395-402. [PMID: 1714956 DOI: 10.1021/jm00112a013] [Citation(s) in RCA: 28] [Impact Index Per Article: 0.8] [Reference Citation Analysis] [What about the content of this article? (0)] [Affiliation(s)] [Abstract] [MESH Headings] [Grants] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 12/28/2022]
Abstract
In order to minimize the deleterious effects of histamine release resulting from the administration to rats and humans of some potent gonadotropin-releasing hormone (GnRH) antagonists, various arginine residues were replaced with the less basic N omega-cyano-N omega-alkyl- or -arylhomoarginine, -arginine, or -p-aminophenylalanine and N omega-triazolyllysine, -ornithine or -p-aminophenylalanine residues in active analogues. These novel analogues were synthesized on a solid-phase support via a two-step modification of the N omega-NH2 of lysine, ornithine, or p-aminophenylalanine residues in otherwise protected resin bound peptides. Most analogues were tested in the rat antiovulatory assay (AOA) and three in vitro assays; a pituitary cell culture assay, a binding assay to pituitary cell membranes, and a histamine release assay. Introduction of the cyanoguanidino and N omega-triazolyl moieties into GnRH analogues yielded several water-soluble antagonists which showed a desirable therapeutic ratio (low histamine release activity to high in vivo potency). Among them, "Azaline" (10, [Ac-DNal1,DCpa2,DPal3,Lys5(atz), DLys6(atz),ILys8,DAla10]GnRH), inhibited ovulation in the rat by 90% at 2 micrograms/rat with an ED50 in the in vitro histamine release assay comparable to that of GnRH itself.
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Affiliation(s)
- P Theobald
- Salk Institute for Biological Studies, La Jolla, California 92186-5800
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Rivier J, Theobald P, Porter J, Perrin M, Gunnet J, Hahn DW, Rivier C. Gonadotropin releasing hormone antagonists: novel structures incorporating N omega-cyano modified guanidine moieties. Biochem Biophys Res Commun 1991; 176:406-12. [PMID: 1850267 DOI: 10.1016/0006-291x(91)90939-5] [Citation(s) in RCA: 5] [Impact Index Per Article: 0.2] [Reference Citation Analysis] [What about the content of this article? (0)] [Affiliation(s)] [Abstract] [MESH Headings] [Grants] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 12/29/2022]
Abstract
A series of GnRH antagonists with substitutions at positions 1, 2, 3, 5 and 6 that included the recently reported homoArg-N omega-cyano-N omega'-alkyl- or Lysine-N epsilon-5'-(3-amino-1H-1,2,4-triazole) [Lys(atz)] amino acid derivatives was synthesized, characterized and tested for antiovulatory and anaphylactoid activities and binding affinity. Overall, these analogs were found to be considerably more soluble at neutral pH than their homologs Nal-Glu or Antide. The decapeptides with these substitutions in positions 5 and/or 6 retained high in vivo potency while those with similar substitutions at positions 1, 2 and 3 were significantly less potent than Nal-Glu or Antide. Of the 16 new analogs reported here, Azaline (Ac-DNal1, DCpa2, DPal3, Lys5(atz),DLys6(atz), ILys8,DA1a10]-GnRH) showed the most promising physico-chemical and biological properties [Lys(atz) = N epsilon-5'-(3-amino-1H-1,2,4-triazole) lysine]. Azaline is readily soluble in dilute buffers at pH 7.0, completely inhibits ovulation at 2.0 to 3.0 micrograms per rat, is equipotent to GnRH in releasing histamine in the rat and has a weaker anaphylactoid response in the rat than other analogs such as Nal-Glu or even Antide.
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Affiliation(s)
- J Rivier
- Salk Institute for Biological Studies, La Jolla, California 92037
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Rath W, Kühnle H, Theobald P, Kuhn W. Objective demonstration of cervical softening with a prostaglandin F2 alpha gel during first trimester abortion. Int J Gynaecol Obstet 1982; 20:195-9. [PMID: 6127245 DOI: 10.1016/0020-7292(82)90071-6] [Citation(s) in RCA: 12] [Impact Index Per Article: 0.3] [Reference Citation Analysis] [What about the content of this article? (0)] [Abstract] [Key Words] [MESH Headings] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 01/18/2023]
Abstract
In a prospective study the cervix softening and dilating effects of intracervically applied prostaglandin F2 alpha gel were investigated in 100 patients during induced abortion in the 7-12th week of pregnancy. A specially designed tonometer was used to measure the resistance of the cervical canal before as well as 6-8 h, 4 days and 5-6 weeks after gel application. The cervix of 99 patients proved to be freely passable without use of undue force for at least Hegar 8 after treatment. Measurements in 96 patients 5-6 weeks after the operation showed good general agreement with those values obtained before gel application. No spontaneous or operation-induced lesions of the cervix occurred. Intracervical prostaglandin gel application proved itself to be a safe, practicable and gentle method for avoiding dilation-induced complications during first trimester abortions.
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Rath W, Theobald P, Kühnle H, Kuhn W, Hilgers H, Weber L. Changes in collagen content of the first trimester cervix uteri after treatment with prostaglandin F2 alpha gel. Arch Gynecol 1982; 231:107-10. [PMID: 7073332 DOI: 10.1007/bf02111661] [Citation(s) in RCA: 12] [Impact Index Per Article: 0.3] [Reference Citation Analysis] [What about the content of this article? (0)] [Key Words] [MESH Headings] [Track Full Text] [Subscribe] [Scholar Register] [Indexed: 01/23/2023]
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Theobald P, Rath W, Voland J. Morphologische Veränderungen an Plazenta und Dezidua nach lokaler intrazervikaler Prostaglandin-Gel-Vorbehandlung. Arch Gynecol Obstet 1981. [DOI: 10.1007/bf02429815] [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: 11/29/2022]
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Wigand KD, Sander H, Theobald P. [Condylomata acuminata of the vaginal portion of uterus. Cytopathology and clinical aspects]. Arch Gynecol 1979; 228:641. [PMID: 485532] [Citation(s) in RCA: 0] [Impact Index Per Article: 0] [Reference Citation Analysis] [What about the content of this article? (0)] [MESH Headings] [Subscribe] [Scholar Register] [Indexed: 12/15/2022]
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Kühnle H, Rath W, Theobald P, Ulbrich R, Grande P. [Induced abortion with prostaglandin gel in the 1st pregnancy trimester]. Arch Gynecol 1979; 228:414. [PMID: 485401] [Citation(s) in RCA: 0] [Impact Index Per Article: 0] [Reference Citation Analysis] [What about the content of this article? (0)] [MESH Headings] [Subscribe] [Scholar Register] [Indexed: 12/15/2022]
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Ulbrich R, Grande P, Kühnle H, Rath W, Theobald P. [Sonography in 74 abortions using prostaglandin F2alpha gel]. Arch Gynecol 1979; 228:421-2. [PMID: 485410] [Citation(s) in RCA: 0] [Impact Index Per Article: 0] [Reference Citation Analysis] [What about the content of this article? (0)] [MESH Headings] [Subscribe] [Scholar Register] [Indexed: 12/15/2022]
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Theobald P, Ulbrich R, Grande P, Kühnle H, Rath W. [Light and electron microscopical studies of cervix following local administration of prostaglandin gel (PGF2alpha)]. Arch Gynecol 1979; 228:417-8. [PMID: 485405] [Citation(s) in RCA: 0] [Impact Index Per Article: 0] [Reference Citation Analysis] [What about the content of this article? (0)] [MESH Headings] [Subscribe] [Scholar Register] [Indexed: 12/15/2022]
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Rath W, Theobald P, Ulbrich R, Grande P, Kühnle H. [Tonometric studies on the pregnant cervix uteri in abortion before and after intracervical administration of prostaglandin F2 gel]. Arch Gynecol 1979; 228:416-7. [PMID: 485404] [Citation(s) in RCA: 0] [Impact Index Per Article: 0] [Reference Citation Analysis] [What about the content of this article? (0)] [MESH Headings] [Subscribe] [Scholar Register] [Indexed: 12/15/2022]
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Theobald P, Pfau P, Rahlf G. [Primary teratogenic choriocarcinoma of the ovary]. Arch Gynecol 1979; 228:440-1. [PMID: 573593] [Citation(s) in RCA: 0] [Impact Index Per Article: 0] [Reference Citation Analysis] [What about the content of this article? (0)] [MESH Headings] [Subscribe] [Scholar Register] [Indexed: 12/23/2022]
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Theobald P, Pfau P. Three cases of choriocarcinoma (author's transl). Geburtshilfe Frauenheilkd 1978; 38:212-9. [PMID: 640365] [Citation(s) in RCA: 0] [Impact Index Per Article: 0] [Reference Citation Analysis] [What about the content of this article? (0)] [Abstract] [MESH Headings] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 12/23/2022] Open
Abstract
Report on three cases of choriocarcinoma which showed interesting features. In the first case a living male infant was delivered two years following chemotherapy for choriocarcinoma and the infant showed no chromosomal abnormalities. In the second case a choriocarcinoma developed three years following a post-partum tubal ligation and the localized tumor was successfully treated by hysterectomy without chemotherapy. In the third case the uterine tumour was refractory to chemotherapy with Actinomycin D and methotrexate and required a hysterectomy. The value of HCG and HPL titres in the differential diagnosis and the value of the microscopic results of the currettings are discussed. The possibility of chromosomal damage to infants born following chemotherapy of the mother is mentioned.
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