A porohyperelastic lubrication model for articular cartilage in the natural synovial joint

This work focuses on the proposed mechanisms for the lubrication of synovial joints and applies them to an idealised bearing geometry considering a porohyperelastic material (cartilage) rotating against a stationary rigid impermeable surface. The model captures the behaviour of all lubrication regimes including fluid film formation and boundary contact as the load capacity is increased, representing a major advancement in modelling cartilage mechanics. Transient responses in the fluid phase are shown to be faster than those in the solid phase with the former decaying over time as fluid is exuded from the material. The complex behaviour of fluid migrating to and from the lubricating film is captured which leads to a better understanding of the hydration and friction mechanisms observed

Fabrication of cartilage-inspired hydrogel/entangled polymer–elastomer structures possessing poro-elastic properties

The ability to replicate the load-bearing properties of articular cartilage is attractive for many engineering applications, particularly bearings where low friction, low wear, and high durability are required. Hydrogels are widely used materials spanning many diverse applications owing to their lubricity and unique mechanical/chemical properties. The poor mechanical characteristics of conventional hydrogels, especially their compressive behavior, limit their application in load-bearing applications despite their favorable properties such as poro/viscoelasticity and lubricity. This paper demonstrates a cartilage-inspired approach to produce a structure that benefits from water-swelling resistant and ultrafast recovery behavior of elastomers as well as the stress-relaxation and energy dissipation properties of hydrogels. A method is presented in this work to fabricate interconnected macro-porous elastomers based on sintering poly(methyl methacrylate) beads. The porous elastomer imparted structural support and resilience to its composite with an infused-grafted hydrogel. At 30% strain and depending upon the strain rate, the composite exhibited a load-bearing behavior that was 14–19 times greater than that of pristine hydrogel and approximately 3 times greater than that of the porous elastomer. The equilibrium elastic modulus of the composite was 452 kPa at a strain range of 10%–30%, which was close to the values reported for the modulus of cartilage tested with similar experimental parameters defined in this study. The dissipated energy for the composite at strain rates of 1 and 10–3 s–1 was enhanced by 25-, 25-, 5-, and 15-fold as compared to that for the pristine hydrogel and the porous elastomer, respectively. The cyclic loading tests at two strain rates showed that the composite immediately recovers its load-bearing properties with the maximum load recovery staying above 95% of its initial values throughout the testing. The permeability of the structures was measured experimentally, and the results showed a decrease of permeability by 3 orders of magnitude following hydrogel grafting

Validation and cultural adaptation of a German version of the Physicians' Reactions to Uncertainty scales

Contains fulltext : 51656.pdf ( ) (Open Access)BACKGROUND: The aim of the study was to examine the validity of a translated and culturally adapted version of the Physicians' Reaction to Uncertainty scales (PRU) in primary care physicians. METHODS: In a structured process, the original questionnaire was translated, culturally adapted and assessed after administering it to 93 GPs. Test-retest reliability was tested by sending the questionnaire to the GPs again after two weeks. RESULTS: The principal factor analysis confirmed the postulated four-factor structure underlying the 15 items. In contrast to the original version, item 5 achieved a higher loading on the 'concern about bad outcomes' scale. Consequently, we rearranged the scales. Good item-scale correlations were obtained, with Pearson's correlation coefficient ranging from 0.56-0.84. As regards the item-discriminant validity between the scales 'anxiety due to uncertainty' and 'concern about bad outcomes', partially high correlations (Pearson's correlation coefficient 0.02-0.69; p < 0.001) were found, indicating an overlap between both constructs. The assessment of internal consistency revealed satisfactory values; Cronbach's alpha of the rearranged version was 0.86 or higher for all scales. Test-retest-reliability, assessed by means of the intraclass-correlation-coefficient (ICC), exceeded 0.84, except for the 'reluctance to disclose mistakes to physicians' scale (ICC = 0.66). In this scale, some substantial floor effects occurred, with 29.3% of answers showing the lowest possible value. CONCLUSION: Dealing with uncertainty is an important issue in daily practice. The psychometric properties of the rearranged German version of the PRU are satisfying. The revealed floor effects do not limit the significance of the questionnaire. Thus, the German version of the PRU could contribute to the further evaluation of the impact of uncertainty in primary care physicians

Informed consent in veterinary medicine: ethical implications for the profession and the animal 'patient'

Informed consent processes are a vital component of both human and veterinary medicine. Current practice encourages veterinarians to learn from insights in the human medical field about how best to achieve valid consent. However, drawing on published literature in veterinary and medical ethics, this paper identifies considerable differences between the purposes of veterinary and human medical consent. Crucially, it is argued that the legal status of animal patients as ‘property’ has implications for the ethical role of veterinary informed consent and the protection of the animal ‘patient’. It is suggested that veterinary informed consent should be viewed as an ethical pivot point where the multiple responsibilities of a veterinary professional converge. In practice, balancing these responsibilities creates considerable ethical challenges. As an example, the paper discusses the renewed call for UK veterinarians to make animal welfare their first priority; we predict that this imperative may increasingly cause veterinary informed consent to become an ethical pressure point due to tensions caused by the often conflicting interests of animals, owners and the veterinary profession. In conclusion, the paper argues that whilst gaining informed consent can often be presented as a robust ethical justification in human medicine, the same cannot be said in veterinary medicine. If the veterinary profession wish to prioritise animal welfare, there is an urgent need to re-evaluate the nature of authority gained through owner informed consent and to consider whether animal patients might need to be better protected outside the consent process in certain circumstances

South African podiatry students’ perceptions of feedback given as part of clinical training

Abstract: As part of their clinical training podiatry students spend time in clinical settings treating patients under the supervision of qualified podiatrists. The role and purpose of feedback during such clinical training is to improve students’ knowledge, skills and behaviour. Feedback is an integral part of the learning process that should enhance students’ clinical learning experiences. However, there is no data on podiatry students’ satisfaction or lack thereof about feedback provided during clinical training. The aim of this study was to determine the perceptions of podiatry students on feedback given or received during clinical training..

Central neuropeptide Y receptors are involved in 3(rd )ventricular ghrelin induced alteration of colonic transit time in conscious fed rats

BACKGROUND: Feeding related peptides have been shown to be additionally involved in the central autonomic control of gastrointestinal functions. Recent studies have shown that ghrelin, a stomach-derived orexigenic peptide, is involved in the autonomic regulation of GI function besides feeding behavior. Pharmacological evidence indicates that ghrelin effects on food intake are mediated by neuropeptide Y in the central nervous system. METHODS: In the present study we examine the role of ghrelin in the central autonomic control of GI motility using intracerobroventricular and IP microinjections in a freely moving conscious rat model. Further the hypothesis that a functional relationship between NPY and ghrelin within the CNS exists was addressed. RESULTS: ICV injections of ghrelin (0.03 nmol, 0.3 nmol and 3.0 nmol/5 μl and saline controls) decreased the colonic transit time up to 43%. IP injections of ghrelin (0.3 nmol – 3.0 nmol kg(-1 )BW and saline controls) decreased colonic transit time dose related. Central administration of the NPY(1 )receptor antagonist, BIBP-3226, prior to centrally or peripherally administration of ghrelin antagonized the ghrelin induced stimulation of colonic transit. On the contrary ICV-pretreatment with the NPY(2 )receptor antagonist, BIIE-0246, failed to modulate the ghrelin induced stimulation of colonic motility. CONCLUSION: The results suggest that ghrelin acts in the central nervous system to modulate gastrointestinal motor function utilizing NPY(1 )receptor dependent mechanisms

EGFR interacts with the fusion protein of respiratory syncytial virus strain 2-20 and mediates infection and mucin expression.

Respiratory syncytial virus (RSV) is the major cause of viral lower respiratory tract illness in children. In contrast to the RSV prototypic strain A2, clinical isolate RSV 2-20 induces airway mucin expression in mice, a clinically relevant phenotype dependent on the fusion (F) protein of the RSV strain. Epidermal growth factor receptor (EGFR) plays a role in airway mucin expression in other systems; therefore, we hypothesized that the RSV 2-20 F protein stimulates EGFR signaling. Infection of cells with chimeric strains RSV A2-2-20F and A2-2-20GF or over-expression of 2-20 F protein resulted in greater phosphorylation of EGFR than infection with RSV A2 or over-expression of A2 F, respectively. Chemical inhibition of EGFR signaling or knockdown of EGFR resulted in diminished infectivity of RSV A2-2-20F but not RSV A2. Over-expression of EGFR enhanced the fusion activity of 2-20 F protein in trans. EGFR co-immunoprecipitated most efficiently with RSV F proteins derived from "mucogenic" strains. RSV 2-20 F and EGFR co-localized in H292 cells, and A2-2-20GF-induced MUC5AC expression was ablated by EGFR inhibitors in these cells. Treatment of BALB/c mice with the EGFR inhibitor erlotinib significantly reduced the amount of RSV A2-2-20F-induced airway mucin expression. Our results demonstrate that RSV F interacts with EGFR in a strain-specific manner, EGFR is a co-factor for infection, and EGFR plays a role in RSV-induced mucin expression, suggesting EGFR is a potential target for RSV disease

Anaesthetist-controlled versus patient-maintained effect-site targeted propofol sedation during elective primary lower-limb arthroplasty performed under spinal anaesthesia (ACCEPTS): study protocol for a parallel-group randomised comparison trial

Background: The clinical efficacy of effect-site targeted patient-maintained propofol sedation (PMPS) compared to anaesthetist-controlled propofol sedation (ACPS) for patients undergoing awake joint replacement surgery is currently unknown. There is no commercially available medical device capable of delivering PMPS so we have designed and built such a device. We plan a clinical trial to compare PMPS to ACPS and to collect data relating to the safety of our prototype device in delivering sedation. Methods: The trial is an open-label, randomised, controlled superiority trial recruiting adults who are undergoing elective primary lower-limb arthroplasty with sedation by propofol infusion by effect-site targeting into two equal-sized parallel arms: PMPS and ACPS. The primary research objective is to compare the body-weight-normalised rate of propofol consumption when sedation for surgery on adults undergoing elective primary lower-limb arthroplasty under spinal anaesthesia is patient-maintained versus when it is anaesthetist-controlled. The study primary null hypothesis is that there is no difference in the rate of propofol consumption when sedation is patient-maintained versus anaesthetist-controlled. Discussion: This is the first trial to test the superiority of effect-site-targeted patient-maintained propofol sedation versus anaesthetist-controlled propofol sedation in terms of total propofol consumption during the sedation period. The results of this trial will help inform clinicians and device manufacturers of the clinical efficacy and safety of patient-maintained propofol sedation applied to a common operative setting. Trial registration: International Standard Randomised Controlled Trial Number Registry, ISRCTN29129799. Prospectively registered on 12 June 2018