Biomaterial interactions with compromised tissue surfaces

This thesis is concerned with the nature of biomaterial interactions with compromised host tissue sites. Both ocular and dermal tissues can be wounded, following injury, disease or surgery, and consequently require the use of a biomaterial. Clear analogies exist between the cornea/tear film/contact lens and the dermal wound bed/wound fluid/skin adhesive wound dressing. The work described in this thesis builds upon established biochemistry to examine specific aspects of the interaction of biomaterials with compromised ocular and dermal tissue sites, with a particular focus on the role of vitronectin. Vitronectin is a prominent cell adhesion glycoprotein present in both tear fluid and wound fluid, and has a role in the regulation and upregulation of plasmin. The interaction of contact lenses with the cornea was assessed by a novel on-lens cell-based vitronectin assay technique. Vitronectin mapping showed that vitronectin-mediated cell adhesion to contact lens surfaces was due to the contact lens-corneal mechanical interaction rather than deposition out of the tear film. This deposition is associated predominantly with the peripheral region of the posterior contact lens surface. The locus of vitronectin deposition on the contact lens surface, which is affected by material modulus, is potentially an important factor in the generation of plasmin in the posterior tear film. Use of the vitronectin mapping technique on ex vivo bandage contact lenses revealed greater vitronectin-mediated cell adhesion to the contact lens surfaces in comparison to lenses worn in the healthy eye. The results suggest that vitronectin is more readily deposited from the impaired corneal tissue bed than the intact healthy tissue bed. Significantly, subjects with a deficient tear film were found to deposit high vitronectin-mediated cell adhesion levels to the BCL surface, thus highlighting the influence of the contact lens-tissue interaction upon deposition. Biomimetic principles imply that adhesive materials for wound applications, including hydrogels and hydrocolloids, should closely match the surface energy parameters of skin. The surface properties of hydrocolloid adhesives were found to be easily modified by contact with siliconised plastic release liners. In contrast, paper release liners did not significantly affect the adhesive surface properties. In order to characterise such materials in the actual wound environment, which is an extremely challenging task, preliminary considerations for the design of an artificial wound fluid model from an animal serum base were addressed.

Ex vivo investigation of novel wound healing therapies and development of a 3-D human skin equivalent wound model

It has previously been found that complexes comprised of vitronectin and growth factors (VN:GF) enhance keratinocyte protein synthesis and migration. More specifically, these complexes have been shown to significantly enhance the migration of dermal keratinocytes derived from human skin. In view of this, it was thought that these complexes may hold potential as a novel therapy for healing chronic wounds. However, there was no evidence indicating that the VN:GF complexes would retain their effect on keratinocytes in the presence of chronic wound fluid. The studies in this thesis demonstrate for the first time that the VN:GF complexes not only stimulate proliferation and migration of keratinocytes, but also these effects are maintained in the presence of chronic wound fluid in a 2-dimensional (2-D) cell culture model. Whilst the 2-D culture system provided insights into how the cells might respond to the VN:GF complexes, this investigative approach is not ideal as skin is a 3-dimensional (3-D) tissue. In view of this, a 3-D human skin equivalent (HSE) model, which reflects more closely the in vivo environment, was used to test the VN:GF complexes on epidermopoiesis. These studies revealed that the VN:GF complexes enable keratinocytes to migrate, proliferate and differentiate on a de-epidermalised dermis (DED), ultimately forming a fully stratified epidermis. In addition, fibroblasts were seeded on DED and shown to migrate into the DED in the presence of the VN:GF complexes and hyaluronic acid, another important biological factor in the wound healing cascade. This HSE model was then further developed to enable studies examining the potential of the VN:GF complexes in epidermal wound healing. Specifically, a reproducible partial-thickness HSE wound model was created in fully-defined media and monitored as it healed. In this situation, the VN:GF complexes were shown to significantly enhance keratinocyte migration and proliferation, as well as differentiation. This model was also subsequently utilized to assess the wound healing potential of a synthetic fibrin-like gel that had previously been demonstrated to bind growth factors. Of note, keratinocyte re-epitheliasation was shown to be markedly improved in the presence of this 3-D matrix, highlighting its future potential for use as a delivery vehicle for the VN:GF complexes. Furthermore, this synthetic fibrin-like gel was injected into a 4 mm diameter full-thickness wound created in the HSE, both keratinocytes and fibroblasts were shown to migrate into this gel, as revealed by immunofluorescence. Interestingly, keratinocyte migration into this matrix was found to be dependent upon the presence of the fibroblasts. Taken together, these data indicate that reproducible wounds, as created in the HSEs, provide a relevant ex vivo tool to assess potential wound healing therapies. Moreover, the models will decrease our reliance on animals for scientific experimentation. Additionally, it is clear that these models will significantly assist in the development of novel treatments, such as the VN:GF complexes and the synthetic fibrin-like gel described herein, ultimately facilitating their clinical trial in the treatment of chronic wounds.

Biochemical profiling of proteins and metabolites in wound exudate from chronic wound environments

The lack of fundamental knowledge on the biological processes associated with wound healing represents a significant challenge. Understanding the biochemical changes that occur within a chronic wound could provide insights into the wound environment and enable more effective wound management. We report on the stability of wound fluid samples under various conditions and describe a high-throughput approach to investigate the altered biochemical state within wound samples collected from various types of chronic, ulcerated wounds. Furthermore, we discuss the viability of this approach in the early stages of wound sample protein and metabolite profiling and subsequent biomarker discovery. This approach will facilitate the detection of factors that may correlate with wound severity and/or could be used to monitor the response to a particular treatment.

The biochemistry of blister fluid from pediatric burn injuries: proteomics and metabolomics aspects

Burn injury is a prevalent and traumatic event for pediatric patients. At present, the diagnosis of burn injury severity is subjective and lacks a clinically relevant quantitative measure. This is due in part to a lack of knowledge surrounding the biochemistry of burn injuries and that of blister fluid. A more complete understanding of the blister fluid biochemistry may open new avenues for diagnostic and prognostic development. Burn insult induces a highly complex network of signaling processes and numerous changes within various biochemical systems, which can ultimately be examined using proteome and metabolome measurements. This review reports on the current understanding of burn wound biochemistry and outlines a technical approach for ‘omics’ profiling of blister fluid from burn wounds of differing severity.

Xanthine oxidoreductase in essential hypertension and metabolic syndrome : Experimental studies on rodent models

Hypertension, obesity, dyslipidemia and dysglycemia constitute metabolic syndrome, a major public health concern, which is associated with cardiovascular mortality. High dietary salt (NaCl) is the most important dietary risk factor for elevated blood pressure. The kidney has a major role in salt-sensitive hypertension and is vulnerable to harmful effects of increased blood pressure. Elevated serum urate is a common finding in these disorders. While dysregulation of urate excretion is associated with cardiovascular diseases, present studies aimed to clarify the role of xanthine oxidoreductase (XOR), i.e. xanthine dehydrogenase (XDH) and its post-translational isoform xanthine oxidase (XO), in cardiovascular diseases. XOR yields urate from hypoxanthine and xanthine. Low oxygen levels upregulate XOR in addition to other factors. In present studies higher renal XOR activity was found in hypertension-prone rats than in the controls. Furthermore, NaCl intake increased renal XOR dose-dependently. To clarify whether XOR has any causal role in hypertension, rats were kept on NaCl diets for different periods of time, with or without a XOR inhibitor, allopurinol. While allopurinol did not alleviate hypertension, it prevented left ventricular and renal hypertrophy. Nitric oxide synthases (NOS) produce nitric oxide (NO), which mediates vasodilatation. A paucity of NO, produced by NOS inhibition, aggravated hypertension and induced renal XOR, whereas NO generating drug, alleviated salt-induced hypertension without changes in renal XOR. Zucker fa/fa rat is an animal model of metabolic syndrome. These rats developed substantial obesity and modest hypertension and showed increased hepatic and renal XOR activities. XOR was modified by diet and antihypertensive treatment. Cyclosporine (CsA) is a fungal peptide and one of the first-line immunosuppressive drugs used in the management of organ transplantation. Nephrotoxicity ensue high doses resulting in hypertension and limit CsA use. CsA increased renal XO substantially in salt-sensitive rats on a high NaCl diet, indicating a possible role for this reactive oxygen species generating isoform in CsA nephrotoxicity. Renal hypoxia, common to these rodent models of hypertension and obesity, is one of the plausible XOR inducing factors. Although XOR inhibition did not prevent hypertension, present experimental data indicate that XOR plays a role in the pathology of salt-induced cardiac and renal hypertrophy.

Synthesis of cadmium oxide and carbon nanotube based nanocomposites and their use as a sensing interface for xanthine detection

Xanthine oxidase (XOD) extracted from bovine milk was immobilized covalently via N-ethyl-N'-(3-dimethylaminopropyl) carbodiimide (EDC) and N-hydroxy succinimide (NHS) chemistry onto cadmium oxide nanoparticles (CdO)/carboxylated multiwalled carbon nanotube (c-MWCNT) composite film electrodeposited on the surface of an Au electrode. The nanocomposite modified Au electrode was characterized by Fourier transform infrared (FTIR), cyclic voltammetry (CV), scanning electron microscopy (SEM) and electrochemical impedance spectroscopy (EIS) before and after immobilization of XOD. Under optimal operation conditions (25 degrees C, + 0.2 V vs. Ag/AgCl, sodium phosphate buffer, pH 7.5), the following characteristics are attributed to the biosensor: linearity of response up to xanthine concentrations of 120 mu M, detection limit of 0.05 mu M (S/N = 3) and a response time of at most 4 s. After being used 100 times over a period of 120 days, only 50% loss of the initial activity of the biosensor was evaluated when stored at 4 degrees C. The fabricated biosensor was successfully employed for the determination of xanthine in fish meat.

Supplemental oxygen, but not supplemental crystalloid fluid, increases tissue oxygen tension in healthy and anastomotic colon in pigs

BACKGROUND: Low tissue oxygen tension is an important factor leading to the development of wound dehiscence and anastomotic leakage after colon surgery. We tested whether supplemental fluid and supplemental oxygen can increase tissue oxygen tension in healthy and injured, perianastomotic, and anastomotic colon in an acutely instrumented pig model of anastomosis surgery. METHODS: Sixteen Swiss Landrace pigs were anesthetized (isoflurane 0.8%-1%) and their lungs ventilated. The animals were randomly assigned to low fluid treatment ("low" group, 3 mL x kg(-1) x h(-1) lactated Ringer's solution) or high fluid treatment ("high" group, 10 mL/kg bolus, 18 mL x kg(-1) x h(-1) lactated Ringer's solution) during colon anastomosis surgery and a subsequent measurement period (4 h). Two-and-half hours after surgery, tissue oxygen tension was recorded for 30 min during ventilation with 30% oxygen. Three hours after surgery, the animals' lungs were ventilated with 100% oxygen for 60 min. Tissue oxygen tension was recorded in the last 30 min. Tissue oxygen tension was measured with polarographic Clark-type electrodes, positioned in healthy colonic wall, close (2 cm) to the anastomosis, and in the anastomosis. RESULTS: In every group, tissue oxygen tension during ventilation with 100% oxygen was approximately twice as high as during ventilation with 30% oxygen, a statistically significant result. High or low volume crystalloid fluid treatment had no effect on colon tissue oxygen tension. CONCLUSIONS: Supplemental oxygen, but not supplemental crystalloid fluid, increased tissue oxygen tension in healthy, perianastomotic, and anastomotic colon tissue.

Wound problems following hip arthroplasty before and after the introduction of a direct thrombin inhibitor for thromboprophylaxis

NICE guidelines have stated that patients undergoing elective hip surgery are at increased risk for venous thromboembolic events (VTE) following surgery and have recommended thromboprophylaxis for 28-35 days1, 2. However the studies looking at the new direct thrombin inhibitors have only looked at major bleeding. We prospectively looked at wound discharge in patients who underwent hip arthroplasty and were given dabigatran postoperatively between March 2010 and April 2010 (n=56). We retrospectively compared these results to a matched group of patients who underwent similar operations six months earlier when all patients were given dalteparin routinely postoperatively until discharge, and discharged home on 150mg aspirin daily for 6 weeks (n=67). Wound discharge after 5 days was significantly higher in the patients taking dabigatran (32% dabigatran n=18, 10% dalteparin n=17, p=0.003) and our rate of delayed discharges due to wound discharge significantly increased from 7% in the dalteparin group (n=5) to 27% for dabigatran (n=15, p=0.004). Patients who received dabigatran were more than five times as likely to return to theatre with a wound complication as those who received dalteparin (7% dabigatran n=4, vs. 1% dalteparin n=1), however, this was not statistically significant (p=0.18). The significantly higher wound discharge and return to theatre rates demonstrated in this study have meant that we have changed our practice to administering dalteparin until the wound is dry and then starting dabigatran. Our study demonstrates the need for further clinical studies regarding wound discharge and dabigatran.

Sensors and imaging for wound healing : a review

Wound healing involves a complex series of biochemical events and has traditionally been managed with 'low tech' dressings and bandages. The concept that diagnostic and theranostic sensors can complement wound management is rapidly growing in popularity as there is tremendous potential to apply this technology to both acute and chronic wounds. Benefits in sensing the wound environment include reduction of hospitalization time, prevention of amputations and better understanding of the processes which impair healing. This review discusses the state-of-the-art in detection of markers associated with wound healing and infection, utilizing devices imbedded within dressings or as point-of-care techniques to allow for continual or rapid wound assessment and monitoring. Approaches include using biological or chemical sensors of wound exudates and volatiles to directly or indirectly detect bacteria, monitor pH, temperature, oxygen and enzymes. Spectroscopic and imaging techniques are also reviewed as advanced wound monitoring techniques. The review concludes with a discussion of the limitations of and future directions for this field.

Microbial colonisation of follicular fluid : alterations in cytokine expression and adverse assisted reproductive technology outcomes

Previous studies have measured cytokine expression within follicular fluid collected at the time of trans-vaginal oocyte retrieval and compared the profiles with the aetiology of infertility and/or successful or unsuccessful assisted reproductive technology (ART) outcomes. Seventy-one paired follicular fluid and vaginal swab specimens collected from ART patients were cultured to detect microorganisms and then were tested for the presence of cytokines by multiplex fluorescence bead assays. Specimen selection was based on two criteria: whether the follicular fluid specimen was colonised (with microorganisms prior to oocyte retrieval) or contaminated by lower genital tract microflora at the time of oocyte retrieval and; the aetiology of infertility...

A wound management education and training needs analysis of health consumers and the relevant health workforce and stocktake of available education and training activities and resources

The goals of this project were to determine the education and training needs of health consumers and the relevant health workforce and to identify and map the available education and training activities and resources. The methods used to collect the data included online surveys and one on one interviews of relevant patients and their carers. The project manager actively sought to engage with the key wound management leaders and advanced clinicians to gain their support and views on the priority education and training issues. The response to all data collection methods was pleasing with almost five hundred responses to the general wound workforce online survey. The data supported the need for more wound management education and training and identified some particular topics of need, such as utilising wound investigations and understanding wound products, pharmaceuticals and devices. The occupational groups with the highest need appear to be those working in primary health care, such as practice nurses and GPs, and those working in residential aged care facilities. The education and training stocktake identified a wide range of activities currently available, the majority being provided in a face to face format. The next stage of the project will be to form some clear and achievable priority action areas based on the available data. An online directory of wound management education and training activities and resources will be developed and further development will be undertaken on a knowledge and skills framework for the wound management workforce. Additionally, transfer of learning factors in the general practice environment will be assessed and strategies will be developed to improve the pre-entry or undergraduate wound management training within relevant higher education programs.

Proteomics in chronic wound research : potentials in healing and health

Chronic wounds, such as venous and diabetic leg ulcers, represent a significant health and financial burden to individuals and healthcare systems. In worst case scenarios this condition may require the amputation of an affected limb, with significant impact on patient quality of life and health. Presently there are no clinical biochemical analyses used in the diagnosis and management of this condition; moreover few biochemical therapies are accessible to patients. This presents a significant challenge in the efficient and efficacious treatment of chronic wounds by medical practitioners. A number of protein-centric investigations have analysed the wound environment and implicated a suite of molecular species predicted to be involved in the initiation or perpetuation of the condition. However, comprehensive proteomic investigation is yet to be engaged in the analysis of chronic wounds for the identification of molecular diagnostic/prognostic markers of healing or therapeutic targets. This review examines clinical chronic wound research and recommends a path towards proteomic investigation for the discovery of medically significant targets. Additionally, the supplementary documents associated with this review provide the first comprehensive summary of protein-centric, small molecule and elemental analyses in clinical chronic wound research.

Development and characterization of a novel, antimicrobial, sterile hydrogel dressing for burn wounds : single-step production with gamma irradiation creates silver nanoparticles and radical polymerization

Patients with burn wounds are susceptible to wound infection and sepsis. This research introduces a novel burn wound dressing that contains silver nanoparticles (SNPs) to treat infection in a 2-acrylamido-2-methylpropane sulfonic acid sodium salt (AMPS-Na(+) ) hydrogel. Silver nitrate was dissolved in AMPS-Na(+) solution and then exposed to gamma irradiation to form SNP-infused hydrogels. The gamma irradiation results in a cross-linked polymeric network of sterile hydrogel dressing and a reduction of silver ions to form SNPs infused in the hydrogel in a one-step process. About 80% of the total silver was released from the hydrogels after 72 h immersion in simulated body fluid solution; therefore, they could be used on wounds for up to 3 days. All the hydrogels were found to be nontoxic to normal human dermal fibroblast cells. The silver-loaded hydrogels had good inhibitory action against Pseudomonas aeruginosa and methicillin-resistant Staphylococcus aureus. Results from a pilot study on a porcine burn model showed that the 5-mM silver hydrogel was efficient at preventing bacterial colonization of wounds, and the results were comparable to the commercially available silver dressings (Acticoat(TM) , PolyMem Silver(®) ). These results support its use as a potential burn wound dressing.

Improving wound management for residents in Residential Aged Care Facilities: National dissemination and implementation of the evidence based Champions for Skin Integrity Program

Overview The incidence of skin tears, pressure injuries and chronic wounds increases with age [1-4] and therefore is a serious issue for staff and residents in Residential Aged Care Facilities (RACFs). A pilot project funded in Round 2 of the Encouraging Best Practice in Residential Aged Care (EBPRAC) program by the then Australian Government Department of Health and Ageing found that a substantial proportion of residents in aged care facilities experienced pressure injuries, skin tears or chronic wounds. It also found the implementation of the evidence based Champions for Skin Integrity (CSI) model of wound care was successful in significantly decreasing the prevalence and severity of wounds in residents, improving staff skills and knowledge of evidence based wound management, increasing staff confidence with wound management, increasing implementation of evidence based wound management and prevention strategies, and increasing staff awareness of their roles in evidence based wound care at all levels [5]. Importantly, during the project, the project team developed a resource kit on evidence based wound management. Two critical recommendations resulting from the project were that: - The CSI model or a similar strategic approach should be implemented in RACFs to facilitate the uptake of evidence based wound management and prevention - The resource kit on evidence based wound management should be made available to all Residential Aged Care Facilities and interested parties A proposal to disseminate or rollout the CSI model of wound care to all RACFs across Australia was submitted to the department in 2012. The department approved funding from the Aged Care Services Improvement Healthy Ageing Grant (ACSIHAG) at the same time as the Round 3 of the Encouraging Better Practice in Aged Care (EBPAC) program. The dissemination involved two crucial elements: 1. The updating, refining and distribution of a Champions for Skin Integrity Resource Kit, more commonly known as a CSI Resource Kit and 2. The presentation of intensive one day Promoting Healthy Skin “Train the Trainer” workshops in all capital cities and major regional towns across Australia Due to demand, the department agreed to fund a second round of workshops focussing on regional centres and the completion date was extended to accommodate the workshops. Later, the department also decided to host a departmental website for a number of clinical domains, including wound management, so that staff from the residential aged care sector had easy access to a central repository of helpful clinical resource material that could be used for improving the health and wellbeing of their older adults, consumers and carers. CSI Resource Kit Upgrade and Distribution: At the start of the project, a full evidence review was carried out on the material produced during the EBPRAC-CSI Stage 1 project and the relevant evidence based changes were made to the documentation. At the same time participants in the EBPRAC-CSI Stage 1 project were interviewed for advice on how to improve the resource material. Following this the documentation, included in the kit, was sent to independent experts for peer review. When this process was finalised, a learning designer and QUT’s Visual Communications Services were engaged to completely refine and update the design of the resources, and combined resource kit with the goal of keeping the overall size of the kit suitable for bookshelf mounting and the cost at reasonable levels. Both goals were achieved in that the kit is about the same size as a 25 mm A4 binder and costs between $19.00 and $28.00 per kit depending on the size of the print run. The dissemination of the updated CSI resource kit was an outstanding success. Demand for the kits was so great that a second print run of 2,000 kits was arranged on top of the initial print run of 4,000 kits. All RACFs across Australia were issued with a kit, some 2,740 in total. Since the initial distribution another 1,100 requests for kits has been fulfilled as well as 1,619 kits being distributed to participants at the Promoting Healthy Skin workshops. As the project was winding up a final request email was sent to all workshop participants asking if they required additional kits or resources to distribute the remaining kits and resources. This has resulted in requests for 200 additional kits and resources. Feedback from the residential aged care sector and other clinical providers who have interest in wound care has been very positive regarding the utility of the kit, (see Appendix 4). Promoting Healthy Skin Workshops The workshops also exceeded the project team’s initial objective. Our goal of providing workshop training for staff from one in four facilities and 450 participants was exceeded, with overwhelming demand for workshop places resulting in the need to provide a second round of workshops across Australia. At the completion of the second round, 37 workshops had been given, with 1286 participants, representing 835 facilities. A number of strategies were used to promote the workshops ranging from invitations included in the kit, to postcard mail-outs, broadcast emailing to all facilities and aged care networks and to articles and paid advertising in aged care journals. The most effective method, by far, was directly phoning the facilities. This enabled the caller to contact the relevant staff member and enlist their support for the workshop. As this is a labour intensive exercise, it was only used where numbers needed bolstering, with one venue rising from 3 registrants before the calls to 53 registrants after. The workshops were aimed at staff who had the interest and the capability of implementing evidence-based wound management within their facility or organisation. This targeting was successful in that a large proportion (68%) of participants were Registered Nurses, Nurse Managers, Educators or Consultants. Twenty percent were Endorsed Enrolled Nurses with the remaining 12% being made up of Personal Care Workers or Allied Health Professionals. To facilitate long term sustainability, the workshop employed train-the-trainer strategies. Feedback from the EBPRAC-CSI Stage 1 interviews was used in the development of workshop content. In addition, feedback from the workshop conducted at the end of the EBPRAC-CSI Stage 1 project suggested that change management and leadership training should be included in the workshops. The program was trialled in the first workshop conducted in Brisbane and then rolled out across Australia. Participants were asked to complete pre and post workshop surveys at the beginning and end of the workshop to determine how knowledge and confidence improved over the day. Results from the pre and post surveys showed significant improvements in the level of confidence in attendees’ ability to implement evidence based wound management. The results also indicated a significant increase in the level of confidence in ability to implement change within their facility or organisation. This is an important indication that the inclusion of change management/leadership training with clinical instruction can increase staff capacity and confidence in translating evidence into practice. To encourage the transfer of the evidence based content of the workshop into practice, participants were asked to prepare an Action Plan to be followed by a simple one page progress report three months after the workshop. These reports ranged from simple (e.g. skin moisturising to prevent skin tears), to complex implementation plans for introducing the CSI model across the whole organisation. Outcomes described in the project reports included decreased prevalence of skin tears, pressure injuries and chronic wounds, along with increased staff and resident knowledge and resident comfort. As stated above, some organisations prepared large, complex plans to roll out the CSI model across their organisation. These plans included a review of the organisation’s wound care system, policies and procedures, the creation of new processes, the education of staff and clients, uploading education and resource material onto internal electronic platforms and setting up formal review and evaluation processes. The CSI Resources have been enthusiastically sought and incorporated into multiple health care settings, including aged care, acute care, Medicare Local intranets (e.g. Map of Medicine e-pathways), primary health care, community and home care organisations, education providers and New Zealand aged and community health providers. Recommendations: Recommendations for RACFs, aged care and health service providers and government  Skin integrity and the evidence-practice gap in this area should be recognised as a major health issue for health service providers for older adults, with wounds experienced by up to 50% of residents in aged care settings (Edwards et al. 2010). Implementation of evidence based wound care through the Champions for Skin Integrity model in this and the pilot project has demonstrated the prevalence of wounds, wound healing times and wound infections can be halved.  A national program and Centre for Evidence Based Wound Management should be established to: - expand the reach of the model to other aged care facilities and health service providers for older adults - sustain the uptake of models such as the Champions for Skin Integrity (CSI) model - ensure current resources, expertise and training are available for consumers and health care professionals to promote skin integrity for all older adults  Evidence based resources for the CSI program and similar projects should be reviewed and updated every 3 – 4 years as per NH&MRC recommendations  Leadership and change management training is fundamental to increasing staff capacity, at all levels, to promote within-organisation dissemination of skills and knowledge gained from projects providing evidence based training Recommendations for future national dissemination projects  A formal program of opportunities for small groups of like projects to share information and resources, coordinate activities and synergise education programs interactively would benefit future national dissemination projects - Future workshop programs could explore an incentive program to optimise attendance and reduce ‘no shows’ - Future projects should build in the capacity and funding for increased follow-up with workshop attendees, to explore the reasons behind those who are unable to translate workshop learnings into the workplace and identify factors to address these barriers.

Inhibition of H2O2 generation in rat liver mitochondria by radical quenchers and phenolic compounds

Generation of H2O2 by rat liver mitochondria with choline, glycerol 1-phosphate and proline as substrates has been shown by using high-concentration phosphate buffer. Rates obtained under these conditions were higher and more consistent as compared with the earlier reports with high-concentration mannitol/sucrose/Tris buffer. Sulphate ions could replace phosphate indicating a requirement for a high concentration of oxygen-containing anions. H2O2 generation was dependent on the presence of native mitochondria and substrate. Maximal rates with various substrates were found to be the same as with succinate. Values of Km and Vmax for H2O2 generation were considerably less than those obtained for respective dehydrogenase activities, measured by dye reduction. Scavengers of O2-. and OH. inhibited generation of H2O2. ATP, ADP, thyronine derivatives and a number of phenolic compounds also showed very potent inhibitory effects of H2O2 generation, whereas phenyl compound had no effect. Phenolic compounds did not have any effect on mitochondrial superoxide dismutase and choline dehydrogenase activities as well as on O2-. generation by the xanthine-xanthine oxidase system. Inhibition by phenolic compounds may have potential for regulation of the intracellular concentration of H2O2, that is not considered to have a "second messenger' function.