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Biomedical subjects

E Jones

Publications and source records attributed to E Jones.

At least 19 recordsLinked to original sources
PubMed2006

Polyurethane unicondylar knee prostheses: simulator wear tests and lubrication studies.

Many materials are used as artificial joint bearing surfaces; these include conventional stainless steel or CoCrMo-on-ultra-high molecular weight polyethylene (UHMWPE), CoCrMo on itself and alumina-on-alumina. However, these joints have a limited lifespan resulting in failure of the prosthesis and the need for revision surgery. A number of materials have been introduced recently in an attempt to overcome these problems. Polycarbonate urethane (PU) is a compliant material that can be used as an artificial joint bearing surface which has been developed to mimic the natural synovial joint more accurately by promoting fluid film lubrication. Tribological tests were performed on CoCrMo-on-PU unicondylar knee prostheses to assess their performance in vitro. The wear produced by these components was considerably lower than that found for conventional joints. They also exhibited low friction and operated close to full-fluid film lubrication with viscosities of lubricant similar to those found in patients with arthritis. These tests gave encouraging results for the tribological performance of this material couple for use as an alternative bearing combination.

Biocompatible Materials↗
PubMed2006

RITA outcomes.

Explore the source record for details and available documents.

Clinical Competence↗
PubMed2006

Effects of exclusive formula or breast milk feeding on oxidative stress in healthy preterm infants.

BACKGROUND: Compared to formula, breast milk is considered to have superior antioxidant properties and consequently may reduce the occurrence of a number of diseases of prematurity associated with oxidative stress. AIMS: To test whether the antioxidant properties of breast milk in healthy premature infants are different to those of formula milk by comparing vitamin E levels in milk and determining the excretion of malondialdehyde (MDA) in urine. METHODS: Vitamin E was measured in the breast milk of 20 mothers who had given birth prematurely. Urinary MDA was measured in 10 exclusively breast milk fed and 10 exclusively formula fed healthy preterm infants receiving no vitamin supplements. MDA was measured after derivatisation with 2,4-dinitrophenylhydrazine and consecutive HPLC with UV detection. RESULTS: Urinary MDA concentrations were consistently very low (0.074+/-0.033 microM/mM Cr and 0.078+/-0.026 microM/mM Cr in breast and formula fed infants respectively) and not significantly different between healthy breast milk and formula fed infants. Both breast and formula milk contained satisfactory levels (0.3-3.0 mg/100 ml) of vitamin E. CONCLUSION: Antioxidant properties of both breast milk and formulae are sufficient to prevent significant lipid peroxidation in healthy premature infants.

Antioxidants↗
PubMed2006

Immunohistochemical analysis of coeliac mucosa following ingestion of oats.

There is now considerable clinical evidence that oats do not activate coeliac disease. Nonetheless, a reluctance to include oats in the gluten-free diet remains. Because gluten-induced damage is accompanied by activation of the gastrointestinal immune system, the purpose of this study was to investigate if similar changes were induced by oats ingestion. Small intestinal histological sections from 10 patients who ingested 50 g of oats daily for 3 months were investigated for possible evidence of immune activation. Tissue obtained before and after oats challenge was stained with a series of antibodies directed against the following molecules: human leucocyte antigen D-related (HLA-DR), Ki-67, CD25, CD54 [intercellular adhesion molecule 1 (ICAM-1)] and mast cell tryptase. None of the patients developed clinical or laboratory evidence of adverse effects. The distribution of intestinal HLA-DR expression was not affected by oats ingestion and the crypt epithelium remained unstained. In the pre-oats biopsies, the percentage of Ki-67 positive enterocytes, 29.5 +/- 6.9 [95% confidence interval (CI) 13.9-45.0] did not differ significantly from that found in post-oats biopsies, 41.2 +/- 3.7 (95% CI, 32.8-49.6), P = 0.19, not significant. Furthermore, oats ingestion did not alter the number of CD25 positive and tryptase positive cells. Finally, the distribution and intensity of ICAM-1 staining was unchanged by dietary oats. In summary, detailed immunohistological studies of biopsies from patients ingesting oats for 3 months did not reveal evidence of immune activation. Together with other reported findings, this study strengthens the view that oats can be included safely in the diet of gluten sensitive patients.

Adult↗
PubMed2006

Sweet problems: insect traits defining the limits to dietary sugar utilisation by the pea aphid, Acyrthosiphon pisum.

Plant phloem sap is an extreme diet for animals, partly because of its high and variable sugar content. The physiological and feeding traits of the pea aphid Acyrthosiphon pisum that define the upper and lower limits to the range of dietary sucrose concentrations utilised by this insect were determined principally using chemically defined diets containing 0.125-1.5 mol l(-1) sucrose. On the diets with 0.125 mol l(-1) and 1.5 mol l(-1) sucrose, the aphids died as larvae within 8 and 14 days of birth, respectively. On the other diets, 60-96% of aphids developed to adulthood, and the 0.5 mol l(-1) and 0.75 mol l(-1) diets supported the highest fecundity. The diet with 0.125 mol l(-1) sucrose was ingested at 36% of the rate of the 0.25 mol l(-1) sucrose diet, but >90% of ingested sucrose-carbon was assimilated on both diets. This suggests that the lower limit is dictated by the aphid feeding response, specifically, a requirement for a minimal concentration of sucrose for sustained feeding. The haemolymph osmotic pressure of aphids on diets with 0.125-1.5 mol l(-1) sucrose was up to 68% higher than on 0.125-1.0 mol l(-1) sucrose diets, but diet consumption and sucrose-carbon assimilation was not reduced on the very high sucrose diets relative to 1.0 mol l(-1) sucrose. This suggests that failure of the osmoregulatory capacity of the insects on high sucrose diets may define the upper limit to the range of dietary sucrose utilised by the aphids. The mean haemolymph osmotic pressure of aphids on plants with phloem sap containing 0.37-0.97 mol l(-1) sucrose was 1.61+/-0.063 MPa (mean +/- s.e.m.), not significantly different from that (1.47+/-0.059 MPa) on diets with 0.25-1.0 mol l(-1) sucrose. It is concluded that the osmoregulatory response of aphids to diets and plants are comparable, and, more generally, that the feeding and osmoregulatory capabilities of the aphids are compatible with the phloem sugar levels commonly encountered by aphids feeding on plants.

Animals↗
PubMed2006

Compliant layer acetabular cups: friction testing of a range of materials and designs for a new generation of prosthesis that mimics the natural joint.

Total joint replacements (TJRs) have a limited lifetime, but the introduction of components that exhibit good lubricating properties with low friction and low wear could extend the life of TJRs. A novel acetabular cup design using polyurethane (PU) as a compliant layer (to mimic the natural joint) has been developed. This study describes a series of friction tests that have been used to select the most appropriate material, optimize the design parameters, and fine-tune the manufacturing processes of these joints. To determine accurately the mode of lubrication under which these joints operate, a synthetic lubricant was used in all these tests. Friction tests were carried out to assess the lubrication of four PU bearing materials. Corethane 80A was the preferred material and was subjected to subsequent testing. Friction tests conducted on acetabular cups, manufactured using Corethane 80A articulating against standard, commercially available femoral heads, demonstrated friction factors approaching those for full-fluid-film lubrication with only approximately 1 per cent asperity contact. As the joint produces these low friction factors within less than half a walking cycle after prolonged periods of loading, start-up friction was not considered to be a critical factor. Cups performed well across the full range of femoral head sizes, but a number of samples manufactured with reduced radial clearances performed with higher than expected friction. This was caused by the femoral head being gripped around the equator by the low clearance cup. To avoid this, the cup design was modified by increasing the flare at the rim. In addition to this the radial clearance was increased. As the material is incompressible, a radial clearance of 0.08 mm was too small for a cup diameter of 32 mm. A clearance of between 0.10 and 0.25 mm produced a performance approaching full-fluid-film lubrication. This series of tests acted as a step towards the optimization of the design of these joints, which has now led to an in vivo ovine model.

Acetabulum↗
PubMed2005

Are the perceptual biases found in chimeric face processing reflected in eye-movement patterns?

Studies of patients with focal brain lesions and neuroimaging indicate that face processing is predominantly based on right hemisphere function. Additionally, experiments using chimeric faces, where the left and the right-hand side of the face are different, have shown that observers tend to bias their responses toward the information on the left. Here, we monitored eye-movements during a gender identification task using blended face images for both whole and chimeric (half female, half male) faces [Neuropsychologia 35 (1997) 685]. As expected, we found a left perceptual bias: subjects based their gender decision significantly more frequently on the left side of the chimeric faces. Analysis of the first saccade showed a significantly greater number of left fixations independent of perceptual bias presumably reflecting the tendency to first inspect the side of the face better suited to face analysis (left side of face/right hemisphere). On top of this though, there was a relationship between response and fixation pattern. On trials where participants showed a left perceptual bias they produced significantly more left saccades and fixated for longer on the left. In contrast, for trials where participants showed a right perceptual bias there was no reliable difference between the number, or total fixation duration, on the left or the right. These results demonstrate that on a trial-by-trial basis subtle differences in the extent of left or right side scanning are related to the perceptual response of the participant, although an overall initial fixation bias to the left occurs irrespective of response bias.

Adult↗
PubMed2005

Design aspects of compliant, soft layer bearings for an experimental hip prosthesis.

Currently, an artificial hip joint can be expected to last, on average, in excess of 15 years with failure due, in the majority of cases, to late aseptic loosening of the acetabular component. A realistic alternative to the problem of wear in conventional joints is the introduction of bearing surfaces that exhibit low wear and operate in the full fluid-film lubrication regime. Contact analyses and friction tests were performed on compliant layer joints (metal-on-polyurethane) and the design of a prototype ovine arthroplasty model was investigated. When optimized, these components have been shown to achieve full fluid-film lubrication.

Animals↗
PubMed2005

Radiographic anatomy of the soft tissue attachments of the equine stifle.

REASONS FOR PERFORMING STUDY: Radiography is a very important aspect of equine stifle imaging. The precise radiographic anatomy of the soft tissue structures of the equine stifle has not been described previously. OBJECTIVE: To describe the anatomical relationship between sites of attachment of soft tissue structures of the equine stifle and their locations on standard radiographic views. METHODS: The sites of bony attachments of the tendons, ligaments and fibrous portion of the joint capsules of equine stifles were determined by gross dissection. These sites of attachment were transposed onto one set of bones deprived of soft tissue and mapped using radiopaque markers. This specimen was then radiographed in the standard radiographic projections (lateromedial, caudocranial and caudal 60 degrees lateral-craniomedial oblique) to determine the position of the attachment sites on the radiographs. RESULTS: Two radiographic maps were drawn per radiographic projection, one for the attachment sites of the ligaments and tendons and one for the attachment sites of the joint capsules. CONCLUSIONS AND POTENTIAL RELEVANCE: The radiographic maps of the precise position of the soft tissue attachments of the tendons, ligaments and joint capsules of the equine stifle should assist interpretation of equine stifle radiographs.

Animals↗
PubMed2005

Effects of three intramedullary pinning techniques on pin location and articular damage in the canine humerus.

The purpose of this study was to compare the pin location and articular damage for intramedullary (IM) pins inserted into the humerus in a directed retrograde, non-directed retrograde, and normograde fashion. Proximal pin positioning in the humerus was significantly more cranial (p < 0.05) using both retrograde techniques when compared to the normograde technique, although this did not cause significant interference with anatomical structures. The distance to the biceps tendon, transverse humeral ligament, and the distal pin location was similar with all insertion techniques, however two of ten pins passed in a non-directed retrograde fashion penetrated the shoulder joint. The results of this study suggest that although non-directed retrograde pinning cannot be recommended, either normograde or retrograde pins directed craniolaterally provide acceptable techniques for insertion of IM pins during distal humeral fracture repair.

Animals↗
PubMed2004

The effect of bone cement particles on the friction of polyethylene and polyurethane knee bearings.

Compliant layer knee joints have been considered for use in an attempt to increase the serviceable life of artificial joints. If designed correctly, these joints should operate within the full-fluid film lubrication regime. However, adverse tribological conditions, such as the presence of bone and bone cement particles, may breach the fluid film and cause surface wear. The frictional behaviour of both polyurethane (PU) and conventional polyethylene (PE) tibial components against a metallic femoral component was therefore assessed when bone cement particles were introduced into the lubricant. The bone cement particles caused a large increase in the frictional torque of both the PE and PU bearings; however, the friction produced by the PU bearings was still considerably lower than that produced by the PE bearings. The volume of bone cement particles between each of the bearings and the resultant frictional torque both decreased over time. This occurred more quickly with the PE bearings but greater damage was caused to the surface of the PE bearings than the PU components.

Biocompatible Materials↗
PubMed2004

Biological evaluation of carbon-fibre-reinforced polybutyleneterephthalate (CFRPBT) employed in a novel acetabular cup.

Polymer composites are potentially useful materials for orthopaedic applications as they can be tailored to closely match the various moduli of bone. The Cambridge epiphyseal cup has been designed using one such material, carbon-fibre-reinforced polybutyleneterephthalate (CFRPBT), so that more of the load can be transferred to bone in order to reduce bone loss around the implant. We have evaluated the suitability of CFRPBT for this application using several standard and custom biological tests, both in vitro and in vivo, and have also started the initial clinical evaluation of the prosthesis. CFRPBT showed no toxicity in bulk form and only minimal toxicity as a particulate. It was non-haemolytic, non-immunogenic and showed no genotoxicity. No adverse responses were seen after in vivo implantation, and the results obtained following 9 months of clinical evaluation have been very encouraging with a good clinical outcome and good bone bonding to the hydroxyapatite-coated CFRPBT.

Acetabulum↗
PubMed2004

Outcome of ICG-assisted ILM peel in macular hole surgery.

PURPOSE: To investigate whether indocyanine green (ICG) staining of the internal limiting membrane (ILM) improves surgical outcome. METHODS: A total of 34 patients were identified who underwent macular hole surgery with ILM peeling augmented with ICG. These were matched retrospectively with 34 patients who underwent macular hole surgery without the use of ICG. Closure rates from primary and secondary procedures were compared, as were changes in Snellen and Logmar visual acuity. RESULTS: There was no significant difference between the two groups with reference to demographic features of age, sex, staging of the macular holes, and the proportion subsequently undergoing cataract surgery. The mean follow-up period was 7.7 months in the ICG group and 6.3 months in the non-ICG group. Closure rates from primary surgery were 91.2% in the ICG group and 73.5% in the non-ICG group (P = 0.056), whereas overall closure rates following further surgery were similar in both groups (94.1 and 91.2%, respectively). Logmar visual improvement above baseline was achieved in 53% of the non-ICG group compared to 82% of the ICG group (P = 0.01). Where primary hole closure occurred, there was no statistically significant difference in visual outcome between the two groups. CONCLUSION: ICG-assisted ILM peel in macular hole surgery is associated with a higher closure rate following a single surgical procedure. This difference was found to approach statistical significance (P = 0.056). Overall visual improvement was greater in the ICG group (P = 0.01); however, this reflected the higher closure rates. Visual outcomes between the two groups were comparable where primary hole closure occurred.

Aged↗
PubMed2004

Treatment of aberrant facial nerve regeneration with botulinum toxin A.

PURPOSE: To assess the effect and efficacy of botulinum toxin type A (BTX-A) at reducing and maintaining eyelid synkinesia in aberrant facial nerve regeneration, while concurrently observing for the presence of side effects to differing treatment doses. METHODS: A prospective interventional study of five patients with eyelid synkinesia resulting from aberrant regeneration of the facial nerve. Patients were treated with injections of either 120, 80 or 40 units of BTX-A (Dysport) into the orbicularis oculi. Objective and subjective reduction in synkinesia, maintenance of response and presence of side effects were recorded. RESULTS: All five patients had improvement of the synkinesia with BTX-A treatment. Lower doses were found to be as effective as higher doses. Mean duration of abolished synkinesia was three months. Two patients developed a ptosis which resolved spontaneously. None of the patients treated with the lowest dose of 40 units developed a ptosis. CONCLUSION: Low-dose BTX-A has a lower incidence of ptosis and is effective in the treatment of aberrant facial nerve regeneration.

Adult↗
PubMed2004

Osteopenia, excess adiposity and hyperleptinaemia during 2 years of treatment for childhood acute lymphoblastic leukaemia without cranial irradiation.

OBJECTIVE: Osteopenia and excess adiposity occur following treatment of childhood acute lymphoblastic leukaemia (ALL) and the use of cranial irradiation is thought to be a significant contributory factor. Hyperleptinaemia has also been demonstrated following cessation of treatment for childhood ALL. Therefore a prospective study was undertaken to evaluate serial changes in percentage bone mineral content (BMC), adiposity and serum leptin concentrations during 2 years of treatment of children with ALL with chemotherapy but without cranial irradiation. DESIGN AND PATIENT: Only patients treated using the MRC ALL 97/ALL 97 (modified 99) protocols for childhood ALL were eligible for entry into the study. A total of 14 patients (seven male, with a median age of 7.5 years (range 3.4-16.7 years) were recruited. Serial dual energy X-ray absorptiometry (DEXA) scanning was undertaken at diagnosis and during two years of treatment. Serum leptin concentrations were determined at the same time as the scans. RESULTS: Reductions in %BMC were observed at the hip and lumbar spine by 12 months (P < 0.01) and remained low after 24 months of treatment. Subanalysis of %BMC measurements at the hip demonstrated a greater reduction in %BMC at the trochanteric region compared to the femoral neck. The percentage corrected fat mass increased from 6 months whereas the body mass index (BMI) standard deviation score (SDS) was increased after 24 months of treatment (P < 0.05). Serum leptin concentrations increased following 24 months of therapy (P < 0.05). CONCLUSIONS: Children treated for ALL with contemporary regimens have a predisposition to osteopenia, excess adiposity and hyperleptinaemia during treatment without cranial irradiation administration. We speculate that in addition to glucocorticoid administration, leptin resistance may account in part for these observations.

Adolescent↗