Exploring the Association between Hemochromatosis and Lower-Limb Venous Disease

OBJECTIVE

Chronic venous disease is a circulatory system dysfunction that has the potential to lead to venous leg ulceration. Although research on the influence of specific gene variants on chronic venous disease has been limited, a few studies have reported an association between hemochromatosis and chronic venous disease. However, no studies have looked at the prevalence of lower-limb venous disease and leg ulcers in people with hemochromatosis. This study aimed to review the existing literature for any association between venous disease and hemochromatosis and investigate the prevalence of venous disease and leg ulcers in people with hemochromatosis.

METHODS

Scoping systematic literature review and cross-sectional study surveying people with hemochromatosis.

RESULTS

This scoping systematic literature review included nine articles and indicated a link between hemochromatosis and venous disease/leg ulcers, although further studies are needed to support this link. Analysis of survey results from people with hemochromatosis found a 9.2% prevalence of leg ulcers in those with self-reported hemochromatosis, considerably higher than the 1% to 3% expected, suggesting that hemochromatosis gene variants may be associated with the pathogenesis of chronic venous disease and leg ulcers.

CONCLUSIONS

This is the first known study to complete a review of the literature regarding hemochromatosis and venous leg ulcers and document the association between hemochromatosis and venous disease/leg ulcers. There is a lack of research in this area and hence limited evidence to guide practice.

Clinical correlates of pain in adults with hard-to-heal leg ulcers: a cross-sectional study

OBJECTIVE

Pain is a complex symptom associated with hard-to-heal (chronic) leg ulcers that is often poorly managed. The objective of this study was to gain greater understanding by investigating relationships between physical and psychosocial factors, and pain severity in adults with hard-to-heal leg ulcers.

METHOD

A secondary analysis of data collected for a longitudinal, observational study of adults with hard-to-heal leg ulcers was undertaken. Data were collected over a 24-week period, including variables relating to sociodemographics, clinical variables, medical status, health, ulcer and vascular histories, and psychosocial measures. Multiple linear regression modelling was used to determine the independent influences of these variables on pain severity, as measured with a Numerical Rating Scale (NRS).

RESULTS

Of 142 participants who were recruited, 109 met the inclusion criteria for this study, of whom: 43.1% had venous ulcers; 41.3% had mixed ulcers; 7.3% had arterial ulcers; and 8.3% had ulcers from some other cause. The final model explained 37% (adjusted r²=0.370) of the variation in the pain NRS scores. Controlling for analgesic use, salbutamol use (p=0.005), clinical signs of infection (p=0.027) and ulcer severity (p=0.001) were significantly associated with increased pain, while the presence of diabetes (p=0.007) was significantly associated with a decrease in pain.

CONCLUSION

Pain is a highly complex and pervasive symptom associated with hard-to-heal leg ulcers. Novel variables were identified as being associated with pain in this population. The model also included wound type as a variable; however, despite being significantly correlated to pain at the bivariate level of analysis, in the final model, the variable did not reach significance. Of the variables included in the model, salbutamol use was the second most significant. This is a unique finding that, to the authors' knowledge, has not been previously reported or studied. Further research is required to better understand these findings and pain in general.

Risk factors for the recurrence of venous leg ulcers in adults: A systematic review protocol

BACKGROUND

Venous leg ulcers are slow to heal, and recurrence is frequent. Living with venous leg ulcers can affect physical and psychological health, and result in financial burden for individuals. Physiological and psychosocial factors are associated with venous leg ulcer recurrence. As over 50% of venous leg ulcers will recur within 12 months of healing, a comprehensive knowledge of holistic risk factors associated with recurrence is required by health professionals involved in the care of the person with venous leg ulcers.

AIM

To develop a systematic review protocol to determine the risk factors for recurrence of venous leg ulcers in adults.

METHOD AND ANALYSIS

This protocol was developed according to the Preferred Reporting Items Form Systematic Review and Meta-Analysis Protocols (PRISMA-P). The inclusion criteria will be based on the PICOS mnemonic-adults with a history of venous leg ulcer/s (participants), risk factor/s under physiological (general/medical), clinical, demographics, psychosocial categories (I (intervention) or E (exposure), venous leg ulcer non-recurrence (comparison group), venous leg ulcer recurrence (outcomes to be measured) and will include study designs of original qualitative, quantitative and mixed method studies (study designs to be included). Methodological quality will be assessed using the Mixed Methods Appraisal Tool. This Systematic Review Protocol was registered in PROSPERO [CRD42021279792].

RESULTS

If meta-analysis is not possible, a narrative review of results will be presented.

CONCLUSIONS

This systematic review on recurrence of venous leg ulcers can provide evidence-based information for preventive strategies for recurrence of a healed venous leg ulcer. The standardised approach outlined in this systematic review protocol offers a rigorous and transparent method to conduct the review.

Decreased mobility, lack of social support, haemosiderosis and use of antidepressant medications may predict recurrent venous leg ulcers within 12 months of healing: A prospective longitudinal study

AIM

To identify clinical, medical and psychosocial predictors of venous leg ulcer recurrence within 12 months of healing.

METHODS

A multi-site study was conducted in Australia in community and hospital outpatient settings. Adults with venous leg ulcers were recruited within 4 weeks of healing and data were collected on preventative treatments and health, medical, clinical and psychosocial factors. Follow-up data on recurrences were collected every 3 months until ulcer recurrence, or until 12 months after healing pending which occurred first. Factors associated with time to recurrence were analysed using a Cox proportional hazards regression model.

DESIGN

Secondary data analysis of a multi-site, prospective longitudinal study to validate a risk assessment tool for recurrence.

RESULTS

A sample of 143 participants was recruited (51% male, M^age = 73 years, SD 13.6). Almost half (49.6%) had an ulcer recurrence within 12 months, with a mean time to ulcer recurrence of 37 weeks (SE 1.63, 95% CI 33.7-40.1). Factors measured at the time of healing that were significant independent predictors of recurrence were: prescribed antidepressant medications (p = .035), presence of haemosiderosis (p = .006), decreased mobility (longer sitting times) (p = .007) and lower social support scale scores (p = .002). Participants who wore compression systems providing 20 mmHg or higher for at least 5 days/week were less likely to recur, although not reaching statistical significance (p = .06).

CONCLUSION

Results provide evidence that antidepressant medications, haemosiderosis, decreased mobility and lack of social support are risk factors associated with ulcer recurrence; therefore, these variables are modifiable and could guide early intervention.

An exploration of knowledge of students and staff at residential aged care facilities and implications for nursing education

BACKGROUND

Advances in healthcare have contributed to population longevity with many older adults living with complex comorbidities, including those in residential aged care facilities (RACFs). Nursing staff require knowledge of gerontology, normal ageing processes and expected physiological, psychosocial, function and cognitive changes in addition to health promotion in order to provide individualised care. The complexity inherent in the medical, palliative and basic care needs of the residents makes RACFs excellent places for learning for undergraduate student nurses who undertake clinical placement as part of a Bachelor of Nursing course. Previous research has identified that knowledge of care staff is relatively poor.

OBJECTIVES

To explore the knowledge and misconceptions of ageing among first year undergraduate nursing students and aged care staff facilitating a placement during a clinical learning experience.

DESIGN

Descriptive cross-sectional design.

SETTING

Three clinical RACFs in Australia.

PARTICIPANTS

First year nursing students and staff of three different RACFs.

METHOD

Pre and post-test clinical placement surveys. Students and staff completed Palmore's Facts on Ageing Quiz, a 25-item tool to assess knowledge and attitudes of ageing, before commencing the clinical placement and on the last day of a two week placement.

RESULTS

Physiological questions were answered correctly. A knowledge deficit was evident from a sociological perspective. Negative attitudes have been found to devalue care and can directly affect the quality of practice in an undesirable way, forming a barrier to effective and therapeutic relationships with older adults, potentially impacting on patient care.

CONCLUSIONS

From an education provider perspective, the inclusion of activities to enrich the learning activities of nurses within RACF- inclusive of reflective activities and guidance from an expert clinical facilitator - may assist in dispelling negative attitudes and stereotypes of the older adult and increase recognition of the value of working with older adults.

Exploring the prevalence and management of wounds for people with dementia in long-term care

The prevalence of wounds and comorbidities such as dementia increase with age. With an ageing population, the likelihood of overlap of these conditions is strong. This study aimed to determine the prevalence of wound types and current management strategies of wound care for people with dementia in long-term care (LTC). A scoping literature review, a cross-sectional observational and chart audit study of residents in dementia specific facilities in LTC were conducted. The scoping review indicated that people with dementia/cognitive impairment are often excluded from wound related studies andof the nine studies included in this review, none looked at the prevalence of types of wounds other then pressure injuries. In the skin audit, skin tears were noted as the most common wound type with some evidence-based practice strategies in place for residents. However, documentation of current wound occurred in less than a third of residents with wounds. This is the first study to note the prevalence of different wound types in people with dementia and current management strategies being used across two dementia-specific facilities and a lack of research in this area limits evidence in guiding practice.

Methods for chronic wound research — A scoping systematic review of the recommendations, guidelines and standards

Background This scoping systematic review aimed to investigate the existing literature for recommendations, guidelines and standards for research on chronic wound diagnosis, assessment, management and prevention; to identify gaps in this literature; and produce recommendations to support future wound management research. Methods A scoping systematic literature review was undertaken in 2017–2018, which aligned with PRISMA guidelines and searched academic databases and grey literature published between 2007 and 2017. Results Eighty-nine documents included recommendations or outcomes on research methods for studies on chronic wound diagnosis, assessment, management and/or prevention; covering the areas of research design, sampling, randomisation and blinding, independent and outcome measures and interventions for research in chronic wounds. Common themes regarding research gaps and flaws were identified. Conclusion This review identified existing evidence, guidelines, recommendations and standards regarding the conduct of chronic wound research internationally. Recommendations include the need for standardised vocabulary, standardised checklists for wound research, development of core outcome datasets and an agreed and standardised set of economic parameters and methodology for cost-effectiveness. Establishment of a centralised national methodology service for wound research to assist with methodology design would be beneficial.

Differences between national and international guidelines for the management of diabetic foot disease

AIM

No studies have investigated if national guidelines to manage diabetic foot disease differ from international guidelines. This study aimed to compare guidelines of Western Pacific nations with the International Working Group on the Diabetic Foot (IWGDF) guidance documents.

METHODS

The 77 recommendations in five chapters of the 2015 IWGDF guidance documents were used as the international gold standard reference. The IWGDF national representative(s) from 12 Western Pacific nations were invited to submit their nation's diabetic foot guideline(s). Four investigators rated information in the national guidelines as "similar," "partially similar," "not similar," or "different" when compared with IWGDF recommendations. National representative(s) reviewed findings. Disagreements in ratings were discussed until consensus agreement achieved.

RESULTS

Eight of 12 nations (67%) responded: Australia, China, New Zealand, Taiwan, and Thailand provided national guidelines; Singapore provided the Association of Southeast Asian Nations guidelines; and Hong Kong and the Philippines advised no formal national diabetic foot guidelines existed. The six national guidelines included were 39% similar/partially similar, 58% not similar, and 2% different compared with the IWGDF recommendations. Within individual IWGDF chapters, the six national guidelines were similar/partially similar with 53% of recommendations for the IWGDF prevention chapter, 42% for wound healing, 40% for infection, 40% for peripheral artery disease, and 20% for offloading.

CONCLUSIONS

National diabetic foot disease guidelines from a large and diverse region of the world showed limited similarity to recommendations made by international guidelines. Differences between recommendations may contribute to differences in national diabetic foot disease outcomes and burdens.

Predicting the likelihood of venous leg ulcer recurrence: The diagnostic accuracy of a newly developed risk assessment tool

The aim of this study was to validate a newly developed tool for predicting the risk of recurrence within 12 months of a venous leg ulcer healing. Performance of the tool to predict recurrence within a 12-month period was assessed using Area Under the Receiver Operating Characteristic Curve (AUC) analysis. Multi-site retrospective and prospective longitudinal studies were undertaken to validate a risk assessment tool for the recurrence of venous leg ulcers within 12 months. In the retrospective study (n = 250), 55% of venous leg ulcers recurred within 12 months, and the risk assessment total score had excellent discrimination and goodness of fit with an AUC of 0.83 (95% CI, 0.76-0.90, P < .001). The prospective study (n = 143) observed that 50.4% (n = 63) of venous leg ulcers recurred within 12 months of healing. Participants were classified using the risk assessment tool as being at low risk (28%), moderate risk (59%), and high risk (13%); the proportion of wounds recurring at 12 months was 15%, 61%, and 67% for each group, respectively. Validation results indicated good discrimination and goodness of fit, with an AUC of 0.73 (95% CI, 0.64-0.82, P < .001). Validation of this risk assessment tool for the recurrence of venous leg ulcers provides clinicians with a resource to identify high-risk patients and to guide decisions on adjunctive, tailored interventions to address the specific risk factors to decrease the risk of recurrence.

Predicting delayed healing: The diagnostic accuracy of a venous leg ulcer risk assessment tool

The aim of this study was to validate a newly developed tool that can predict the risk of failure to heal of a venous leg ulcer in 24 weeks. The risk assessment tool was validated, and performance of the tool was assessed using Area Under the Receiver Operating Characteristic Curve (AUC) analysis. Retrospective and prospective validation was conducted through multi-site, longitudinal studies. In the retrospective study (n = 318), 30% of ulcers did not heal within 24 weeks, with the tool demonstrating an AUC of 0.80 (95% CI, 0.68-0.93, P < .001) for the total score. In the prospective study across 10 clinical sites (n = 225), 31% (n = 68) of ulcers did not heal within 24 weeks. Participants were classified with the RAT at enrolment as being at low risk (27%), moderate risk (53%) or high risk (20%) of delayed healing; the proportion of wounds unhealed at 24 weeks was 6%, 29% and 59%, respectively. Validation results of the total score indicated good discrimination and goodness of fit with an AUC of 0.78 (95% CI, 0.71-0.85, P < .001). Validation of this risk assessment tool offers assurance that realistic outcomes can be predicted for patients, and scores can guide early decisions on interventions to address specific risk factors for failing to heal, thus promoting timely healing.

Predicting the Likelihood of Delayed Venous Leg Ulcer Healing and Recurrence: Development and Reliability Testing of Risk Assessment Tools

Venous leg ulcers are characterized by a long healing process and repeated cycles of ulceration. A secondary analysis of data from multisite longitudinal studies was conducted to identify risk factors for delayed healing and recurrence of venous leg ulcers for development of risk assessment tools, and a single-site prospective study was performed to as- sess the new tools' interrater reliability (IRR). The development of the risk assessment tools was based on results from previous multivariate analyses combined with further risk factors documented in the literature from systematic reviews, randomized controlled trials, and cohort studies with regard to delayed healing and recurrence. The delayed healing tool contained 10 items, including patient demographics, living status, use of high-compression therapy, ulcer area, wound bed tissue type, and percent reduction in ulcer area after 2 weeks. The recurrence tool included 8 items, including his- tory of deep vein thrombosis, duration of previous ulcer, history of previous ulcers, body mass index, living alone, leg elevation, walking, and compression. Using consensus procedures, content validity was established by an advisory group of 21 expert multidisciplinary clinicians and researchers. To determine intraclass correlation (ICC) and IRR, 3 rat- ers assessed 26 patients with an open ulcer and 22 with a healed ulcer. IRR analysis indicated statistically signi cant agreement for the delayed healing tool (ICC 0.84; 95% con dence interval [CI], 0.70-0.92; P <.001) and the recurrence tool (ICC 0.88; 95% CI, 0.75-0.94; P <.001). The development and reliability results of these risk assessment tools meet the recommendations for evidence-based, reliable tools and may bene t clinicians and patients in the management of venous leg ulcers. Studies to examine the items with low ICC scores and to determine the predictive validity of these tools are warranted.

Impact of audio-visual storytelling in simulation learning experiences of undergraduate nursing students

BACKGROUND

Use of high fidelity simulation has become increasingly popular in nursing education to the extent that it is now an integral component of most nursing programs. Anecdotal evidence suggests that students have difficulty engaging with simulation manikins due to their unrealistic appearance. Introduction of the manikin as a 'real patient' with the use of an audio-visual narrative may engage students in the simulated learning experience and impact on their learning. A paucity of literature currently exists on the use of audio-visual narratives to enhance simulated learning experiences.

OBJECTIVE

This study aimed to determine if viewing an audio-visual narrative during a simulation pre-brief altered undergraduate nursing student perceptions of the learning experience.

DESIGN

A quasi-experimental post-test design was utilised.

PARTICIPANTS

A convenience sample of final year baccalaureate nursing students at a large metropolitan university.

METHODS

Participants completed a modified version of the Student Satisfaction with Simulation Experiences survey. This 12-item questionnaire contained questions relating to the ability to transfer skills learned in simulation to the real clinical world, the realism of the simulation and the overall value of the learning experience. Descriptive statistics were used to summarise demographic information. Two tailed, independent group t-tests were used to determine statistical differences within the categories.

RESULTS

Findings indicated that students reported high levels of value, realism and transferability in relation to the viewing of an audio-visual narrative. Statistically significant results (t=2.38, p<0.02) were evident in the subscale of transferability of learning from simulation to clinical practice. The subgroups of age and gender although not significant indicated some interesting results.

CONCLUSIONS

High satisfaction with simulation was indicated by all students in relation to value and realism. There was a significant finding in relation to transferability on knowledge and this is vital to quality educational outcomes.

Incidence and risk factors for developing infection in patients presenting with uninfected diabetic foot ulcers

OBJECTIVE

There is a paucity of research on patients presenting with uninfected diabetic foot ulcers (DFU) that go on to develop infection. We aimed to investigate the incidence and risk factors for developing infection in a large regional cohort of patients presenting with uninfected DFUs.

METHODS

We performed a secondary analysis of data collected from a validated prospective state-wide clinical diabetic foot database in Queensland (Australia). Patients presenting for their first visit with an uninfected DFU to a Diabetic Foot Service in one of thirteen Queensland regions between January 2012 and December 2013 were included. Socio-demographic, medical history, foot disease history, DFU characteristics and treatment variables were captured at the first visit. Patients were followed until their DFU healed, or if their DFU did not heal for 12-months, to determine if they developed a foot infection in that period.

RESULTS

Overall, 853 patients were included; mean(standard deviation) age 62.9(12.8) years, 68.0% male, 90.9% type 2 diabetes, 13.6% indigenous Australians. Foot infection developed in 342 patients for an overall incidence of 40.1%; 32.4% incidence in DFUs healed <3 months, 55.9% in DFUs healed between 3-12 months (p<0.05). Independent risk factors (Odds Ratio (95% confidence interval)) for developing infection were: DFUs healed between 3-12 months (2.3 (1.6-3.3)), deep DFUs (2.2 (1.2-3.9)), peripheral neuropathy (1.8 (1.1-2.9)), previous DFU history (1.7 (1.2-2.4)), foot deformity (1.4 (1.0-2.0)), female gender (1.5 (1.1-2.1)) and years of age (0.98 (0.97-0.99)) (all p<0.05).

CONCLUSIONS

A considerable proportion of patients presenting with an uninfected DFU will develop an infection prior to healing. To prevent infection clinicians treating patients with uninfected DFUs should be particularly vigilant with those presenting with deep DFUs, previous DFU history, peripheral neuropathy, foot deformity, younger age, female gender and DFUs that have not healed by 3 months after presentation.

Ulcer area reduction at 2 weeks predicts failure to heal by 24 weeks in the venous leg ulcers of patients living alone

OBJECTIVE

Chronic wounds are costly and affect approximately 1-2% of the population. Venous disease is responsible for about 60% of all chronic leg ulcers and these ulcers can be debilitating, with evidence of a decreased quality of life. Unfortunately, up to 30% of venous leg ulcers (VLUs) fail to heal, despite best practice treatment. This study aimed to identify risk factors associated with delayed healing in participants with VLUs and in particular, whether psychosocial factors play a part in this process.

METHOD

A secondary analysis was conducted of a large data set of clinical, wound healing, health, social, economic and psychological data collected in previous prospective studies of participants with VLUs. Generalised linear mixed modelling was used to identify independent predictors of failure to heal after 24 weeks.

RESULTS

We recruited 247 participants with 318 VLUs from hospital and community settings. Findings revealed that four early predictors were independently significantly associated with failure to heal by 24 weeks. These were: participants who lived alone (OR 2.3, 95%CI [1.13-4.61], p=0.03); had less than 25% reduction in ulcer area within two weeks of treatment (OR 10.07, 95%CI [4.60-22.19], p<0.001); had higher ulcer severity scores (OR 5.1, 95%CI [2.33-11.88], p=0.001); and participants who were not treated with high level compression therapy (i.e.>30 mmHg) at the time of assessment (OR 4.18, 95% CI [1.95-8.97], p=0.002).

CONCLUSION

Identified risk factors offer an opportunity for clinicians to determine realistic outcomes for their patients and to guide decisions on early referral and implementation of tailored adjunctive interventions. Additionally, findings from this study suggest health professionals need to assess and address not only clinical risk factors but also social risk factors, when planning interventions to promote healing.

Activation of Yap-Directed Transcription by Knockdown of Conserved Cellular Functions

The Yap-Hippo pathway has a significant role in regulating cell proliferation and growth, thus controlling organ size and regeneration. The Hippo pathway regulates two highly conserved, transcription coactivators, YAP and TAZ. The upstream regulators of the Yap-Hippo pathway have not been fully characterized. The aim of this study was to use a siRNA screen, in a liver biliary cell line, to identify regulators of the Yap-Hippo pathway that allow activation of the YAP transcription coactivator at high cell density. Activation of the YAP transcription coactivator was monitored using a high-content, image-based assay that measured the intracellular localization of native YAP protein. Active siRNAs were identified and further validated by quantification of CYR61 mRNA levels (a known YAP target gene). The effect of compounds targeting the putative gene targets identified as hits was also used for further validation. A number of validated hits reveal basic aspects of Yap-Hippo biology, such as components of the nuclear pore, by which YAP cytoplasmic-nuclear shuttling occurs, or how proteasomal degradation regulates intracellular YAP concentrations, which then alter YAP localization and transcription. Such results highlight how targeting conserved cellular functions can lead to validated activity in phenotypic assays.

Risk factors for delayed healing in venous leg ulcers: a review of the literature

BACKGROUND

Chronic leg ulcers, remaining unhealed after 4-6 weeks, affect 1-3% of the population, with treatment costly and health service resource intensive. Venous disease contributes to approximately 70% of all chronic leg ulcers and these ulcers are often associated with pain, reduced mobility and a decreased quality of life. Despite evidence-based care, 30% of these ulcers are unlikely to heal within a 24-week period and therefore the recognition and identification of risk factors for delayed healing of venous leg ulcers would be beneficial.

AIM

To review the available evidence on risk factors for delayed healing of venous leg ulcers.

METHODS

A review of the literature in regard to risk factors for delayed healing in venous leg ulcers was conducted from January 2000 to December 2013. Evidence was sourced through searches of relevant databases and websites for resources addressing risk factors for delayed healing in venous leg ulcers specifically.

RESULTS

Twenty-seven studies, of mostly low-level evidence (Level III and IV), identified risk factors associated with delayed healing. Risk factors that were consistently identified included: larger ulcer area, longer ulcer duration, a previous history of ulceration, venous abnormalities and lack of high compression. Additional potential predictors with inconsistent or varying evidence to support their influence on delayed healing of venous leg ulcers included: decreased mobility and/or ankle range of movement, poor nutrition and increased age.

DISCUSSION

Findings from this review indicate that a number of physiological risk factors are associated with delayed healing in venous leg ulcers and that social and/or psychological risk factors should also be considered and examined further.

CONCLUSION

The findings from this review can assist health professionals to identify prognostic indicators or risk factors significantly associated with delayed healing in venous leg ulcers. This will facilitate realistic outcome planning and inform implementation of appropriate early strategies to promote healing.

Provisional Matrix Deposition in Hemostasis and Venous Insufficiency: Tissue Preconditioning for Nonhealing Venous Ulcers

Significance: Chronic wounds represent a major burden on global healthcare systems and reduce the quality of life of those affected. Significant advances have been made in our understanding of the biochemistry of wound healing progression. However, knowledge regarding the specific molecular processes influencing chronic wound formation and persistence remains limited. Recent Advances: Generally, healing of acute wounds begins with hemostasis and the deposition of a plasma-derived provisional matrix into the wound. The deposition of plasma matrix proteins is known to occur around the microvasculature of the lower limb as a result of venous insufficiency. This appears to alter limb cutaneous tissue physiology and consequently drives the tissue into a 'preconditioned' state that negatively influences the response to wounding. Critical Issues: Processes, such as oxygen and nutrient suppression, edema, inflammatory cell trapping/extravasation, diffuse inflammation, and tissue necrosis are thought to contribute to the advent of a chronic wound. Healing of the wound then becomes difficult in the context of an internally injured limb. Thus, interventions and therapies for promoting healing of the limb is a growing area of interest. For venous ulcers, treatment using compression bandaging encourages venous return and improves healing processes within the limb, critically however, once treatment concludes ulcers often reoccur. Future Directions: Improved understanding of the composition and role of pericapillary matrix deposits in facilitating internal limb injury and subsequent development of chronic wounds will be critical for informing and enhancing current best practice therapies and preventative action in the wound care field.

The effectiveness of a four-layer compression bandage system in comparison with Class 3 compression hosiery on healing and quality of life in patients with venous leg ulcers: a randomised controlled trial

An increasing number of compression systems available for treatment of venous leg ulcers and limited evidence on the relative effectiveness of these systems are available. The purpose of this study was to conduct a randomised controlled trial to compare the effectiveness of a four-layer compression bandage system and Class 3 compression hosiery on healing and quality of life (QL) in patients with venous leg ulcers. Data were collected from 103 participants on demographics, health, ulcer status, treatments, pain, depression and QL for 24 weeks. After 24 weeks, 86% of the four-layer bandage group and 77% of the hosiery group were healed (P = 0·24). Median time to healing for the bandage group was 10 weeks, in comparison with 14 weeks for the hosiery group (P = 0·018). The Cox proportional hazards regression found participants in the four-layer system were 2·1 times (95% CI 1·2-3·5) more likely to heal than those in hosiery, while longer ulcer duration, larger ulcer area and higher depression scores significantly delayed healing. No differences between groups were found in QL or pain measures. Findings indicate that these systems were equally effective in healing patients by 24 weeks; however, a four-layer system may produce a more rapid response.

Inhibition of bacterial IF2 binding to fMet-tRNA((fMet)) by aminoglycosides

Screening for inhibitors of bacterial protein synthesis Initiation Factor 2 (IF2) binding to N-formyl-Methionyl-transfer RNA (fMet-tRNA((fMet))) identified a series of aminoglycosides, that included amikacin and kanamycin A1, as inhibitors of this interaction. Subsequent testing revealed that aminoglycosides displayed a wide range of inhibitory activity. However, the failure of these compounds to completely inhibit binding of IF2 to fMet-tRNA((fMet)), the known ability of aminoglycosides to bind RNA, and the ability of the aminoglycosides to displace PicoGreen bound to fMet-tRNA((fMet)) suggest these compounds act by binding fMet-tRNA((fMet)). This hypothesis is further supported by isothermal denaturation experiments that failed to show any interaction between the IF2 protein and the aminoglycosides.

The identification and characterization of hydrazinyl urea-based antibacterial agents through combinatorial chemistry

An effort to identify novel inhibitors of peptidoglycan synthesis with antibacterial activity resulted in the discovery of a series of biaryl urea-based antibacterial agents through isolation of a by-product from a mixture-based combinatorial library of semi-carbazones and subsequent parallel synthesis efforts. The compounds were shown to possess broad spectrum antibacterial activity against gram-positive drug resistant pathogens, and showed apparent specificity for disruption of the bacterial cell wall biosynthesis pathway.

Use of combinatorial library screening to identify inhibitors of a bacterial two-component signal transduction kinase

Bacterial resistance to antibiotics is emerging as a major concern to the medical community. The appearance of several antibiotic-resistant strains, including multidrug-resistant Staphylococcus aureus, raises the prospect that infections by these bacteria could soon become untreatable with currently available antibiotics. In order to address this problem, increased emphasis is being placed on the discovery of novel classes of antibacterial agents that inhibit novel molecular targets using sources of compounds not yet exploited for antibiotic drug discovery. Novel classes of compounds can now be rapidly investigated using combinatorial chemistry approaches. This report describes the identification of novel antibacterial compounds from a combinatorial library of N-acetylated, C-amidated D-amino acid hexapeptides. This library of compounds was screened for inhibitors of CheA, a member of the bacterial two-component signal transduction kinase family. Several peptides with apparent IC50 values in the low micromolar range were identified. In addition to inhibiting CheA, these peptides inhibited mammalian protein kinase C (from rat brain) with comparable potency. Finally, these peptides were also found to have significant antibacterial properties, although the true mechanism by which they exhibited inhibition of bacterial growth remains uncertain.

Application of nearest-neighbor and cluster analyses in pharmaceutical lead discovery

High throughput screening (HTS) programs based on diverse collections of compounds can rapidly identify leads for potential drug candidates. In cases where the compound collection is truly diverse, one may only identify a few compounds of interest. However, where a large number of hits are identified, it becomes necessary to examine the structures to determine the true number of compound classes involved so that follow-up studies may be conducted as efficiently as possible. In this case, cluster analysis is applied to determine the structural relationship among HTS hits. To efficiently expand around the region of the hit (or a class of hits) in chemical space, we have applied nearest neighbors analysis to select additional compounds from collections of a large number of commercial vendors, achieving an average hit rate in excess of 15%. Applying these techniques in a number of different cases, we obtained results that are useful for subsequent investigations of hits from HTS and other relevant molecular structures from the literature.

Stereoselectivity of DNA catenane fusion by resolvase

Communications between distant sites on DNA often depend on the way in which the sites are connected. For example, site-specific recombination catalysed by Tn3 resolvase is most efficient when the 114-base-pair res recombination sites are directly repeated in the same DNA molecule. In vitro a supercoiled plasmid substrate containing two directly repeated res sites gives a resolution product in which the two recombinant circles are topologically linked as a simple (two-noded) catenane (Fig. 1a). Resolvase is highly selective in forming this product rather than unlinked circles or more complex catenanes. It does not catalyse recombination between sites on separate supercoiled molecules, or between inverted sites in the same supercoiled molecule. Tn3 resolution removes four negative supercoils from the substrate, an energetically favourable change which may drive the reaction: in relaxed or nicked circular substrates, resolution is incomplete and slower. Resolvase can catalyse fusion of the circles of a nicked or relaxed catenane, giving a single unknotted circular product. The fusion is the precise topological reversal of resolution, introducing four negative supercoils into a relaxed catenane substrate, and should therefore not proceed if the catenane is already negatively supercoiled. Here we study recombination between res sites in non-supercoiled DNA circles linked into simple catenanes. We used (+2) and (-2) catenanes, which differ only in the direction in which one circle is threaded through the other (Fig. 2a). Although stereoselectivity is a feature of enzyme catalysis, it is not obvious how resolvase can distinguish between these subtly different catenane diastereomers. A model for the intertwining of the res site DNA in the catalytically active complex predicts that only the (-2) catenane will recombine, giving unknotted and 4-noded knot circular products. We have confirmed this prediction for the Tn3 and Tn21 resolvases.

Dynamics of long-range interactions on DNA: the speed of synapsis during site-specific recombination by resolvase

A noninvasive method for monitoring communications on DNA was developed from the specificity of resolvase for the arrangement of its recombinational sites. Constraints in DNA structure, caused by interactions between distant sites, can be detected by resolvase as they arise. The method was used to follow the formation and decay of synaptic intermediates during site-specific recombination by resolvase. Synaptic complexes were formed very rapidly, at a rate limited by the initial association of the protein with DNA rather than the physical motion of DNA segments. The recombinational sites seem to encounter each other by an ordered motion, perhaps dictated by DNA supercoiling instead of random collisions, so that the first encounter produces the active complex.

Site-specific recombination by mutants of Tn21 resolvase with DNA recognition functions from Tn3 resolvase

The resolvases from the transposons Tn3 and Tn21 are homologous proteins but they possess distinct specificities for the DNA sequence at their respective res sites. The DNA binding domain of resolvase contains an amino acid sequence that can be aligned with the helix-turn-helix motif of other DNA binding proteins. Mutations in the gene for Tn21 resolvase were made by replacing the section of DNA that codes for the helix-turn-helix with synthetic oligonucleotides. Each mutation substituted one amino acid in Tn21 resolvase with either the corresponding residue from Tn3 resolvase or a residue that lacks hydrogen bonding functions. The ability of these proteins to mediate recombination between res sites from either Tn21 or Tn3 was measured in vivo and in vitro. With one exception, where a glutamate residue had been replaced by leucine, the activity of these mutants was similar to that of wild-type Tn21 resolvase. A further mutation was made in which the complete recognition helix of Tn21 resolvase was replaced with that from Tn3 resolvase. This protein retained activity in recombining Tn21 res sites, though at a reduced level relative to wild-type; the reduction can be assigned entirely to weakened binding to this DNA. Neither this mutant nor any other derivative of Tn21 resolvase had any detectable activity for recombination between res sites from Tn3. The exchange of this section of amino acid sequence between the two resolvases is therefore insufficient to alter the DNA sequence specificity for recombination.