A spatial causal network approach for multi-stressor risk analysis and mapping for environmental impact assessments

Environmental impact assessment (EIA) relies on rigorous scientific assessment of all potential causal pathways by which large-scale developments may impact on valued assets in a region. Despite their importance to informed decision-making, many EIAs are flawed by incomplete analysis of causal pathways, limited spatial assessment and a lack of transparency about how risks have been evaluated across the region. To address these, we describe an EIA methodology based on network analysis of potential causal pathways in a given region. This network approach is coupled with a systematic evaluation of the likelihood, consequence and mitigation options for each causal pathway from one or more human activities to multiple valued assets. The method includes analysis of the confidence in these evaluations, recognizing where knowledge gaps constrain assessments of risks to particular assets. The causal network approach is complemented by a spatially explicit analysis of the region that allows residual risk (i.e. risk remaining after all feasible mitigations) to be mapped for all valued assets. This identifies which activities could lead to potential impacts of varying concern (rated from 'very low' to 'very high'), their likely pathways, which valued assets are at risk and where these residual risks are greatest. The output maps reveal 'risk hotspots' where more detailed local-scale assessments and monitoring should focus. The method is demonstrated by application to potential impacts on 8 valued assets (aquifers, ecosystems and protected species) due to unconventional gas resource development in the Cooper Basin, central Australia. Results show which activities and causal pathways are of potential concern to different valued assets and where residual risk is greatest for particular species and ecosystems. This spatial causal network provides a systematic, consistent and transparent assessment of potential impacts, improving the quality of decision-making about planned developments and their environmental risks.

River ecosystem conceptual models and non-perennial rivers: A critical review

Conceptual models underpin river ecosystem research. However, current models focus on continuously flowing rivers and few explicitly address characteristics such as flow cessation and drying. The applicability of existing conceptual models to nonperennial rivers that cease to flow (intermittent rivers and ephemeral streams, IRES) has not been evaluated. We reviewed 18 models, finding that they collectively describe main drivers of biogeochemical and ecological patterns and processes longitudinally (upstream-downstream), laterally (channel-riparian-floodplain), vertically (surface water-groundwater), and temporally across local and landscape scales. However, perennial rivers are longitudinally continuous while IRES are longitudinally discontinuous. Whereas perennial rivers have bidirectional lateral connections between aquatic and terrestrial ecosystems, in IRES, this connection is unidirectional for much of the time, from terrestrial-to-aquatic only. Vertical connectivity between surface and subsurface water occurs bidirectionally and is temporally consistent in perennial rivers. However, in IRES, this exchange is temporally variable, and can become unidirectional during drying or rewetting phases. Finally, drying adds another dimension of flow variation to be considered across temporal and spatial scales in IRES, much as flooding is considered as a temporally and spatially dynamic process in perennial rivers. Here, we focus on ways in which existing models could be modified to accommodate drying as a fundamental process that can alter these patterns and processes across spatial and temporal dimensions in streams. This perspective is needed to support river science and management in our era of rapid global change, including increasing duration, frequency, and occurrence of drying.

Flow intermittence and ecosystem services in rivers of the Anthropocene

Intermittent rivers and ephemeral streams (IRES) are watercourses that cease flow at some point in time and space. Arguably Earth's most widespread type of flowing water, IRES are expanding where Anthropocenic climates grow drier and human demands for water escalate.However, IRES have attracted far less research than perennial rivers and are undervalued by society, jeopardizing their restoration or protection. Provision of ecosystem services by IRES is especially poorly understood, hindering their integration into management plans in most countries.We conceptualize how flow intermittence governs ecosystem service provision and transfers at local and river-basin scales during flowing, non-flowing and dry phases. Even when dry or not flowing, IRES perform multiple ecosystem services that complement those of nearby perennial rivers.Synthesis and applications. Conceptualizing how flow intermittence in rivers and streams governs ecosystem services has applied a socio-ecological perspective for validating the ecosystem services of intermittent rivers and ephemeral streams. This can be applied at all flow phases and in assessing impacts of altered flow intermittence on rivers and their ecosystem services in the Anthropocene.

Biotic and abiotic variables influencing plant litter breakdown in streams: a global study

Plant litter breakdown is a key ecological process in terrestrial and freshwater ecosystems. Streams and rivers, in particular, contribute substantially to global carbon fluxes. However, there is little information available on the relative roles of different drivers of plant litter breakdown in fresh waters, particularly at large scales. We present a global-scale study of litter breakdown in streams to compare the roles of biotic, climatic and other environmental factors on breakdown rates. We conducted an experiment in 24 streams encompassing latitudes from 47.8° N to 42.8° S, using litter mixtures of local species differing in quality and phylogenetic diversity (PD), and alder (Alnus glutinosa) to control for variation in litter traits. Our models revealed that breakdown of alder was driven by climate, with some influence of pH, whereas variation in breakdown of litter mixtures was explained mainly by litter quality and PD. Effects of litter quality and PD and stream pH were more positive at higher temperatures, indicating that different mechanisms may operate at different latitudes. These results reflect global variability caused by multiple factors, but unexplained variance points to the need for expanded global-scale comparisons.

Standard and emerging treatment options for diabetic neuropathy

Diabetic neuropathy is a common complication of diabetes mellitus affecting 30-50% of patients and is a major cause for increased costs, morbidity and mortality. Strict diabetes control prevents this complication and may restore neurologic deficits in the early stages. Several efforts have been undertaken to alter the natural history of this complication, including the use of aldose reductase and protein kinase-C inhibitors, as well as antioxidants. Available data so far do not support the use of aldose reductase inhibitors due to safety issues and efficacy. Protein kinase-C inhibitors have provided encouraging initial results but their development has been halted. Antioxidants, like a-lipoic acid, improve some neurological deficits and painful symptoms. There are effective and safe medications such as anticonvulsants, antidepressants and opioids for the management of patients with painful symptoms. In this revew we present standard and emerging treatment modalities for the etiologic and symptomatic treatment of diabetic neuropathy.

Amputations and foot-related hospitalisations disproportionately affect dialysis patients

Patients with diabetes have increased risk for foot ulcers, amputations and hospitalisations. We evaluated a closed cohort of patients with diabetes and established risk factors in two high risk groups: (i) dialysis patients and (ii) patients with previous foot ulceration. We used claims data for diabetes (ICD-9 250.X), ulceration (ICD-9 707·10, 707·14 and 707·15) and dialysis (CPT 90935-90937) from the Scott and White Health Plan to identify 150 consecutive patients with diabetes on dialysis (dialysis group) and 150 patients with a history of foot ulceration (ulcer history group). We verified these diagnoses by manually reviewing corresponding electronic medical records. Each patient was provided 30 months follow-up period. The incidence of foot ulcers was the same in dialysis patients and patients with an ulcer history (210 per 1000 person-years). The amputation incidence rate was higher in dialysis patients (58·0 versus 13·3, P < 0·001). Hospital admission was common in both study groups. The incidence of hospitalisation was higher in the ulcer history group (477·3 versus 381·3, P < 0·001); however, there were more foot-related hospital admissions in the dialysis group (32·9% versus 14·0%, P < 0·001) during the 30-month evaluation period. The incidence of ulcers, amputations and all-cause hospitalisations is high in persons with diabetes and a history of foot ulceration or on dialysis treatment; however, those on dialysis treatment have disproportionately higher rates of foot-related hospitalisations. Intervention strategies to reduce the burden of diabetic foot disease must target dialysis patients as a high-risk group.

Corneal confocal microscopy detects early nerve regeneration in diabetic neuropathy after simultaneous pancreas and kidney transplantation

Diabetic neuropathy is associated with increased morbidity and mortality. To date, limited data in subjects with impaired glucose tolerance and diabetes demonstrate nerve fiber repair after intervention. This may reflect a lack of efficacy of the interventions but may also reflect difficulty of the tests currently deployed to adequately assess nerve fiber repair, particularly in short-term studies. Corneal confocal microscopy (CCM) represents a novel noninvasive means to quantify nerve fiber damage and repair. Fifteen type 1 diabetic patients undergoing simultaneous pancreas-kidney transplantation (SPK) underwent detailed assessment of neurologic deficits, quantitative sensory testing (QST), electrophysiology, skin biopsy, corneal sensitivity, and CCM at baseline and at 6 and 12 months after successful SPK. At baseline, diabetic patients had a significant neuropathy compared with control subjects. After successful SPK there was no significant change in neurologic impairment, neurophysiology, QST, corneal sensitivity, and intraepidermal nerve fiber density (IENFD). However, CCM demonstrated significant improvements in corneal nerve fiber density, branch density, and length at 12 months. Normalization of glycemia after SPK shows no significant improvement in neuropathy assessed by the neurologic deficits, QST, electrophysiology, and IENFD. However, CCM shows a significant improvement in nerve morphology, providing a novel noninvasive means to establish early nerve repair that is missed by currently advocated assessment techniques.

An extensive primary nodular melanoma of the foot with associated distant metastases: a case report

A Nodular Melanoma of the foot is a relatively uncommon disease, which accounts for the dearth of literature. The anatomical location of a primary malignant melanoma is of prognostic importance as primary lesions of the foot and ankle have poorer prognostic outcomes. This single case reports a life-threatening presentation, of a primary nodular melanoma of the foot with associated distant metastases of the skeletal system, organs and lymph nodes.

Gait-related strategies for the prevention of plantar ulcer development in the high risk foot

High plantar pressures lead to ulceration in the diabetic foot, particularly in the forefoot region around the metatarsal heads. High plantar pressures persist during gait due to factors such as peripheral neuropathy, foot deformities, limited ankle dorsi flexion range of motion and reduced plantar tissue thickness. Strategies impinging upon gait such as the use of appropriate therapeutic footwear, custom-moulded insoles and injectable silicone can help to reduce plantar pressures and attenuate the risk for ulceration. Shoes adapted with external rocker profiles facilitate plantar flexion and restrict sagittal plane motion of the metatarsophalangeal joint, reducing pressures in the region of the metatarsal heads. Insoles custom-moulded to patient's feet help to reduce plantar pressures and minimise the risk of ulceration in the forefoot region. The loss of subcutaneous fat tissue in the diabetic foot enhances bony prominences and predisposes the foot to high-pressure areas. Silicone is a biocompatible material that can be safely injected into plantar soft tissue to augment tissue thickness and prevent the development of ulceration. This enhancement to the subcutaneous layer is remarkably well retained and is a generally well-adopted procedure in the clinical setting.

Methicillin-resistant Staphylococcus aureus in diabetic foot infections

Diabetic foot ulcers are often complicated by infection. Among pathogens, Staphylococcus aureus predominates. The prevalence of methicillin-resistant S. aureus (MRSA) in infected foot ulcers is 15-30% and there is an alarming trend for increase in many countries. There are also data that recognize new strains of MRSA that are resistant to vancomycin. The risk for MRSA isolation increases in the presence of osteomyelitis, nasal carriage of MRSA, prior use of antibacterials or hospitalization, larger ulcer size and longer duration of the ulcer. The need for amputation and surgical debridement increases in patients infected with MRSA. Infections of mild or moderate severity caused by community-acquired MRSA can be treated with cotrimoxazole (trimethoprim/sulfamethoxazole), doxycycline or clindamycin when susceptibility results are available, while severe community-acquired or hospital-acquired MRSA infections should be managed with glycopeptides, linezolide or daptomycin. Dalbavancin, tigecycline and ceftobiprole are newer promising antimicrobial agents active against MRSA that may also have a role in the treatment of foot infections if more data on their efficacy and safety become available.

eNOS gene polymorphism association with retinopathy in type 1 diabetes

PURPOSE

Nitric oxide (NO) is a major mediator in vascular biology, regulating blood pressure and regional blood flow. NO and the enzymes required for its production may contribute to the aetiology of vascular pathologies. In diabetes, over-production of NO might play a role in the development of diabetic nephropathy, while reduced NO production may be related to the development of diabetic retinopathy and neuropathy, where VEGF (vascular endothelial growth factor) levels are increased in a counter regulatory manner. Among the three nitric oxide synthase (NOS) enzymes most attention has focussed on endothelial NOS (eNOS) because of its relevance to angiopathies.

METHODS

In this study the influence of a single nucleotide polymorphism at position -786 in the eNOS gene, where there is a C/T base substitution, on development of type 1 diabetes mellitus (T1DM) and its microvascular complications was studied in 249 British Caucasian type 1 diabetics using a case-control association design. Genotyping was carried out using PCR-RFLP technique.

RESULTS

There was a significant association between the polymorphism -786*C/T and both T1DM and diabetic retinopathy. The distribution of eNOS gene polymorphism genotype frequencies showed a significant difference observed between diabetic patients and healthy controls [CC+CT vs. TT p = 0.05, OR = 1.5 95%CI(0.9-2.5)]. The genotype frequencies for eNOS gene polymorphism was also significantly different between diabetic retinopaths and healthy controls [CC+CT vs. TT p = 0.0000 OR = 3.4 95%CI(1.9-6.1) No significant differences for eNOS allele and genotype frequencies were found in other groups compared to the controls.

CONCLUSION

Therefore, eNOS gene variation may be a factor in the genetic propensity to T1DM and diabetic retinopathy that may have a prognostic value or may suggest interventional approaches to regulate eNOS in patients with diabetes.

Charcot neuroarthropathy triggered by osteomyelitis and/or surgery

INTRODUCTION

Charcot neuroarthropathy (CN) is a rare but devastating complication of diabetic neuropathy. Osteomyelitis is also a complication of the diabetic foot and it may be difficult to differentiate from CN.

PATIENTS AND METHODS

A patient with Type 1 diabetes and peripheral neuropathy developed a foot ulcer complicated by osteomyelitis of the first proximal phalanx. He was successfully treated with antibiotics and surgical excision of the infected bone. Six months later, he developed a hot, swollen, red foot and X-ray showed destruction of the second and third metatarsal heads. At the second presentation, it was difficult to determine whether this was a recurrence of osteomyelitis or a new onset of CN. Thus, to obtain a definitive diagnosis, recourse was made to more sophisticated imaging techniques.

RESULTS

99mTc methylenediphosphonate (MDP) bone scans and magnetic resonance imaging proved inconclusive to differentiate between osteomyelitis and CN. Subsequently, an indium-labelled white cell scan confirmed the absence of osteomyelitis and the patient was successfully treated for CN.

DISCUSSION

Infection and/or surgery may be predisposing factors in the development of diabetic CN but the combination of the two could accelerate the onset of the Charcot process in people with diabetes and neuropathy.

Genetic association analyses of non-synonymous single nucleotide polymorphisms in diabetic nephropathy

AIMS/HYPOTHESIS

Diabetic nephropathy, characterised by persistent proteinuria, hypertension and progressive kidney failure, affects a subset of susceptible individuals with diabetes. It is also a leading cause of end-stage renal disease (ESRD). Non-synonymous (ns) single nucleotide polymorphisms (SNPs) have been reported to contribute to genetic susceptibility in both monogenic disorders and common complex diseases. The objective of this study was to investigate whether nsSNPs are involved in susceptibility to diabetic nephropathy using a case-control design.

METHODS

White type 1 diabetic patients with (cases) and without (controls) nephropathy from eight centres in the UK and Ireland were genotyped for a selected subset of nsSNPs using Illumina's GoldenGate BeadArray assay. A chi (2) test for trend, stratified by centre, was used to assess differences in genotype distribution between cases and controls. Genomic control was used to adjust for possible inflation of test statistics, and the False Discovery Rate method was used to account for multiple testing.

RESULTS

We assessed 1,111 nsSNPs for association with diabetic nephropathy in 1,711 individuals with type 1 diabetes (894 cases, 817 controls). A number of SNPs demonstrated a significant difference in genotype distribution between groups before but not after correction for multiple testing. Furthermore, neither subgroup analysis (diabetic nephropathy with ESRD or diabetic nephropathy without ESRD) nor stratification by duration of diabetes revealed any significant differences between groups.

CONCLUSIONS/INTERPRETATION

The nsSNPs investigated in this study do not appear to contribute significantly to the development of diabetic nephropathy in patients with type 1 diabetes.

Rehabilitating agricultural streams in Australia with wood: a review

Worldwide, the ecological condition of streams and rivers has been impaired by agricultural practices such as broadscale modification of catchments, high nutrient and sediment inputs, loss of riparian vegetation, and altered hydrology. Typical responses include channel incision, excessive sedimentation, declining water quality, and loss of in-stream habitat complexity and biodiversity. We review these impacts, focusing on the potential benefits and limitations of wood reintroduction as a transitional rehabilitation technique in these agricultural landscapes using Australian examples. In streams, wood plays key roles in shaping velocity and sedimentation profiles, forming pools, and strengthening banks. In the simplified channels typical of many agricultural streams, wood provides habitat for fauna, substrate for biofilms, and refuge from predators and flow extremes, and enhances in-stream diversity of fish and macroinvertebrates.Most previous restoration studies involving wood reintroduction have been in forested landscapes, but some results might be extrapolated to agricultural streams. In these studies, wood enhanced diversity of fish and macroinvertebrates, increased storage of organic material and sediment, and improved bed and bank stability. Failure to meet restoration objectives appeared most likely where channel incision was severe and in highly degraded environments. Methods for wood reintroduction have logistical advantages over many other restoration techniques, being relatively low cost and low maintenance. Wood reintroduction is a viable transitional restoration technique for agricultural landscapes likely to rapidly improve stream condition if sources of colonists are viable and water quality is suitable.

Biodiversity, functional roles and ecosystem services of groundwater invertebrates

Recent surveys of groundwater invertebrates (stygofauna) worldwide are yielding rich troves of biodiversity, with significant implications for invertebrate systematists and phylogeneticists as well as ecologists and groundwater managers. What is the ecological significance of this high biodiversity of invertebrates in some aquifers? How might it influence groundwater ecosystem services such as water purification or bioremediation? In terrestrial ecosystems, biodiversity is typically positively correlated with rates of ecosystem functions beneficial to humans (e.g. crop pollination). However, the links between biodiversity, ecosystem function, and ecosystem services in groundwater are unknown. In some aquifers, feeding, movement and excretion by diverse assemblages of stygofauna potentially enhance groundwater ecosystem services such as water purification, bioremediation and water infiltration. Further, as specific taxa apparently play ‘keystone’ roles in facilitating ecosystem services, declines in abundance or even their extinction have serious repercussions. One way to assess the functional significance of biodiversity is to identify ‘ecosystem service providers’, characterise their functional relationships, determine how service provision is affected by community structure and environmental variables, and measure the spatio-temporal scales over which these operate. Examples from Australian and New Zealand alluvial aquifers reveal knowledge gaps in understanding the functional importance of most stygofauna, hampering effective protection of currently undervalued groundwater ecosystem services.

A comparison of diabetic foot ulcer outcomes using negative pressure wound therapy versus historical standard of care

Diabetic foot ulcers (DFUs) are a leading cause of morbidity and hospitalisation among patients with diabetes. We analysed claims data for Medicare part B diabetic foot ulcer patients treated with Negative Pressure Wound Therapy at home (N = 1135) and diabetic foot ulcer patients from a published meta-analysis of randomised controlled wet-to-moist therapy. The expected costs of care for the two treatments were also compared. A significantly greater proportion of wounds treated with NPWT achieved a successful treatment endpoint compared with wet-to-moist therapy at both 12 weeks (39.5% versus 23.9%; P < 0.001) and 20 weeks (46.3% versus 32.8%; P < 0.001). NPWT-treated patients reached a successful wound treatment endpoint more rapidly, and the benefit was apparent in all wound sizes. Expected 20-week treatment costs for NPWT were similar to those for wet-to-moist therapy if one nursing visit per day for the latter is assumed but 42% less if two nursing visits per day are made. Thus, NPWT may improve the proportion of DFUs that attain a successful wound treatment endpoint and decrease resource utilisation by a given health care system compared with standard wet-to-moist therapy.

Foot ulcer risk is lower in South-Asian and african-Caribbean compared with European diabetic patients in the U.K.: the North-West diabetes foot care study

OBJECTIVE

To determine 1) foot ulcer rates for European, South-Asian, and African-Caribbean diabetic patients in the U.K and 2) the contribution of neuropathy and peripheral arterial disease (PAD) differences to altered ulcer risk between the groups.

RESEARCH DESIGN AND METHODS

In this U.K. population-based study, we screened 15,692 type 1 and type 2 diabetic patients in the community health care setting for foot ulcers, foot deformities, neuropathy, and PAD plus other characteristics. In total, 13,409 were European (85.5%), 1,866 were South Asian (11.9%), and 371 were African Caribbean (2.4%).

RESULTS

The age-adjusted prevalence of diabetic foot ulcers (past or present) for Europeans, South Asians, and African Caribbeans was 5.5, 1.8, and 2.7%, respectively (P < 0.0001). Asians and African Caribbeans had less neuropathy, PAD, and foot deformities than Europeans (P = 0.003). The unadjusted risk of ulcer (odds ratio [OR]) for Asians versus Europeans was 0.29 (95% CI 0.20-0.41) (P < 0.0001). PAD, neuropathy, foot deformities, and insulin use attenuated the age-adjusted OR from 0.32 to 0.52 (0.35-0.76) (P < 0.0001). African-Caribbean versus European ulcer risk in males was attenuated from 0.60 to 0.71 by vibration sensation.

CONCLUSIONS

South Asians with diabetes in the U.K. have about one-third the risk of foot ulcers of Europeans. The lower levels of PAD, neuropathy, insulin usage, and foot deformities of the Asians account for approximately half of this reduced foot ulcer risk. Lower neuropathy is the main contributor to the reduced African-Caribbean ulcer rate, particularly in men. The reasons for these ethnic differences warrant further investigation.

Pathogenesis of foot ulcers and the need for offloading

Diabetic foot ulceration represents a major medical, social and economic problem all over the world. While more than 5% of diabetic patients have a history of foot ulceration, the cumulative lifetime incidence may be as high as 15%. Ethnic differences exist in both ulcer and amputation incidences. Foot ulceration results from the interaction of several contributory factors, the most important of which is neuropathy. The use of the total-contact cast is demonstrated in the treatment of plantar neuropathic ulcers. Histological evidence suggests that pressure relief results in chronic foot ulcers changing their morphological appearance by displaying some features of an acute wound. Thus, repetitive stresses on the insensate foot appear to play a major role in maintaining ulcer chronicity. It is hoped that research activity in foot disease will ultimately result in fewer ulcers and less amputation in diabetes.

The effect of silicone injections in the diabetic foot on peak plantar pressure and plantar tissue thickness: a 2-year follow-up

OBJECTIVE

To report the efficacy of injected liquid silicone (ILS) in the foot at 2 years after administration.

DESIGN

Randomized controlled trial.

SETTING

Diabetic foot clinic in the United Kingdom.

PARTICIPANTS

Twenty-eight diabetic neuropathic patients, randomized into an active treatment group (n=14) and a placebo group (n=14).

INTERVENTION

Participants were given either 6 injections of 0.2mL of liquid silicone (silicone group) or equal volumes of saline (placebo group) under metatarsal head sites with callus.

MAIN OUTCOME MEASURES

Plantar tissue thickness and plantar pressures were measured at 3, 6, 12, and 24 months postinjection.

RESULTS

At 12 months, the plantar tissue thickness in the silicone group had increased by a mean 1.6+/-0.9mm (P=.001), and remained increased at 24 months (1.1+/-0.7mm, P=.003). Peak plantar pressure in the silicone group was reduced at 12 months (-165.0+/-253.5kPa, P=.03), but not at 24 months. There was no change in tissue thickness or peak plantar pressure in the placebo group at 12 and 24 months. The reduction in the pressure time integral (PTI) in the silicone group did not reach significance at 12 months (-.71+/-1.17kPa/s, P=.055). Although PTI returned to baseline at 24 months for the silicone group, it was significantly increased in the placebo group (.64+/-.37kPa/s, P=.043), suggesting that silicone may still exhibit some pressure-reducing properties after 24 months.

CONCLUSIONS

The results indicate that at 24 months postinjection the cushioning properties of ILS have reduced, suggesting that booster injections may be required in certain patients.

Update on Charcot neuroarthropathy

Charcot neuroarthropathy is not uncommon in diabetic patients with peripheral neuropathy. Often, the condition is misdiagnosed for cellulitis or osteomyelitis and treatment is delayed. A high index of suspicion is required in these patients to initiate appropriate treatment early. This article covers the pathogeneses of this condition and briefly describes the recent studies performed to understand the underlying etiopathogenetic factors of this devastating condition. Lastly, it mentions the recently completed multicenter trial using bisphosphonates in diabetic Charcot neuroarthropathy.

Bisphosphonates in the treatment of Charcot neuroarthropathy: a double-blind randomised controlled trial

AIMS/HYPOTHESIS

The management of charcot neuroarthropathy, a severe disabling condition in diabetic patients with peripheral neuropathy, is currently inadequate with no specific pharmacological treatment available. We undertook a double-blind randomised controlled trial to study the effect of pamidronate, a bisphosphonate, in the management of acute diabetic Charcot neuroarthropathy.

METHODS

Altogether 39 diabetic patients with active Charcot neuroarthropathy from four centres in England were randomised in a double-blind placebo-controlled trial. Patients received a single infusion of 90 mg of pamidronate or placebo (saline). Foot temperatures, symptoms and markers of bone turnover (bone specific alkaline phosphatase and deoxypyridinoline crosslinks) were measured over the 12 months, in 10 visits. All patients also had standard treatment of the Charcot foot.

RESULTS

Mean age of the study group (59 % Type II (non-insulin-dependent) diabetes mellitus) was 56.3 +/- 10.2 years. The mean temperature difference between active and control groups was 3.6 +/- 1.7 degrees C and 3.3 +/- 1.4 degrees C, respectively. There was a fall in temperature of the affected foot in both groups after 2 weeks with a further reduction in temperature in the active group at 4 weeks (active and placebo vs baseline; p = 0.001; p = 0.01, respectively), but no difference was seen between groups. An improvement in symptoms was seen in the active group compared with the placebo group (p < 0.001). Reduction in bone turnover (means +/- SEM) was greater in the active than in the control group. Urinary deoxypyridinoline in the pamidronate treated group fell to 4.4 +/- 0.4 nmol/mmol creatinine at 4 weeks compared with 7.1 +/- 1.0 in the placebo group (p = 0.01) and bone-specific alkaline phosphatase fell to 14.1 +/- 1.2 u/l compared with 18.6 +/- 1.6 u/l after 4 weeks, respectively (p = 0.03).

CONCLUSION/INTERPRETATION

The bisphosphonate, pamidronate, given as a single dose leads to a reduction in bone turnover, symptoms and disease activity in diabetic patients with active Charcot neuroarthropathy.

Analysis of the association between diabetic nephropathy and polymorphisms in the aldose reductase gene in Type 1 and Type 2 diabetes mellitus

AIMS

To investigate the association between polymorphisms of the aldose reductase gene and diabetic nephropathy in both Type 1 and Type 2 diabetes mellitus, and to carry out a meta-analysis of published results.

METHODS

We have investigated the role of two aldose reductase polymorphisms in four independent cohorts of cases and controls (two each with Type 1 and Type 2 diabetes) drawn from two ethnic populations, including 471 patients with nephropathy and 494 control diabetic patients without nephropathy. A C/T transition at position -106, and a (CA)n microsatellite marker 2.1 kb from the start site of the aldose reductase gene were genotyped in nephropathic patients and non-nephropathic controls from each cohort.

RESULTS

Carriage of the -106 T allele was significantly associated with diabetic nephropathy in three of the four study groups. The Mantel-Haenszel combined odds ratio was 2.22 (95% CI 1.69, 2.94), P = 1.05 x 10(-8). We found no evidence for association of the microsatellite marker with nephropathy, despite moderate levels of disequilibrium between the two markers. Meta-analysis of published data yielded no evidence for association of the microsatellite marker with diabetic nephropathy in Type 2 diabetes, but varying degrees of association with diabetic nephropathy in Type 1 diabetes.

CONCLUSIONS

Meta-analyses provide more convincing evidence of a role for the ALR2-106 marker than for the microsatellite marker in diabetic nephropathy (DN). More studies are now required to confirm these results and to establish whether the ALR2-106 polymorphism has a functional role in DN.

A role for mitogen-activated protein kinases in the etiology of diabetic neuropathy

The onset of diabetic neuropathy, a complication of diabetes mellitus, has been linked to poor glycemic control. We tested the hypothesis that the mitogen-activated protein kinases (MAPK) form transducers for the damaging effects of high glucose. In cultures of adult rat sensory neurons, high glucose activated JNK and p38 MAPK but did not result in cell damage. However, oxidative stress activated ERK and p38 MAPKs and resulted in cellular damage. In the dorsal root ganglia of streptozotocin-induced diabetic rats (a model of type I diabetes), ERK and p38 were activated at 8 wk duration, followed by activation of JNK at 12 wk duration. We report activation of JNK and increases in total levels of p38 and JNK in sural nerve of type I and II diabetic patients. These data implicate MAPKs in the etiology of diabetic neuropathy both via direct effects of glucose and via glucose-induced oxidative stress.

Treatments for diabetic neuropathy

The management of symptomatic diabetic sensory neuropathy presents a therapeutic challenge to the practicing physician. Two approaches are outlined in this article. First, symptomatic therapies, which will not influence the natural history of painful neuropathy, are discussed. These include, in addition to the stable glycemic control, tricyclic drugs, a number of anticonvulsant and antiarrhythmic agents, and opioid-like medications. Topical therapies and nonpharmalogic approaches are also discussed. With the exception of near normoglycemia, treatments that may slow the progression of neuropathy are experimental and include aldose reductase inhibitors, antioxidants, and other agents. Finally, the approach to patients without symptoms but with sensory loss is discussed.

Continuous activity monitoring in persons at high risk for diabetes-related lower-extremity amputation

This study evaluated the magnitude and location of activity of diabetic patients at high risk for foot amputation. Twenty subjects aged 64.6 +/- 1.8 years with diabetes, neuropathy, deformity, or a history of lower-extremity ulceration or partial foot amputation were dispensed a continuous activity monitor and a log book to record time periods spent in and out of their homes for 1 week. The results indicate that patients took more steps per hour outside their home, but took more steps per day inside their homes. Although 85% of the patients wore their physician-approved shoes most or all of the time while they were outside their homes, only 15% continued to wear them at home. Focusing on protection of the foot during in-home ambulation may be an important factor on which to focus future multidisciplinary efforts to reduce the incidence of ulceration and amputation. The ability to continuously monitor the magnitude, duration, and time of activity ultimately may assist clinicians in dosing activity just as they dose drugs.

Sildenafil citrate for the treatment of erectile dysfunction in men with Type II diabetes mellitus

AIMS/HYPOTHESIS

Ninety percent of all men with diabetes have Type II (non-insulin-dependent) diabetes mellitus, and erectile dysfunction (ED) is common in this patient group. This study evaluated the effects of sildenafil on men with erectile dysfunction and Type II diabetes and compared the results with glycated haemoglobin concentrations and chronic diabetic complications.

METHODS

Patients (mean age, 59 years) in this double-blind, placebo-controlled trial were randomised to sildenafil (25-100 mg; n = 110) or matching placebo (n = 109) for 12 weeks. Primary criteria for efficacy included questions 3 (achieving an erection) and 4 (maintaining an erection) from the International Index of Erectile Function (IIEF, score range, 0-5). Secondary outcome measures included a global efficacy question (GEQ), patient event logs, a life satisfaction checklist, and the remaining IIEF questions.

RESULTS

After 12 weeks, the mean scores for questions 3 and 4 had improved significantly in patients receiving sildenafil (3.42 +/- 0.23 and 3.35 +/- 0.24) compared with placebo (1.86 +/- 0.22 and 1.84 +/- 0.23; p < 0.0001). Similarly, the GEQ score was higher in the sildenafil (64.6 %) than the placebo group (10.5 %). Even when correlating efficacy with glycated haemoglobin concentrations ( < or = 8.3 % or > 8.3 %, the median concentration found in this study) or the number of diabetic complications (0 or > or = 1), the mean scores for the GEQ and questions 3 and 4 from the IIEF remained higher for all the sildenafil groups compared with the placebo groups (p < 0.0001).

CONCLUSION/INTERPRETATION

Sildenafil was well-tolerated and effective in improving erectile dysfunction in men with Type II diabetes, even in patients with poor glycaemic control and chronic complications.

Peripheral vascular and nerve function associated with lower limb amputation in people with and without diabetes

Multiple factors, including peripheral vascular disease and neuropathy, contribute to the development and perpetuation of complications of the lower extremities in diabetes. The main aim of the present study was to assess the peripheral vascular and nerve status of diabetic and non-diabetic subjects that had undergone lower limb amputation. Various non-invasive tests of peripheral vascular and nerve function were carried out on subjects who had undergone unilateral lower limb amputation and were now attending a Rehabilitation Centre. The control group (n=23), the diabetic amputee group (n=64) and the non-diabetic amputee group (n=32) were age-matched. Only the diabetic amputee group had evidence of medial arterial calcification. Transcutaneous oxygen levels were significantly lower in the diabetic amputee group (median 43 mmHg; interquartile range 33-49 mmHg) than in the control (59; 56-74 mmHg) and non-diabetic amputee (57; 43-65 mmHg) groups (control compared with diabetic amputee group, P<0.001; diabetic amputee compared with non-diabetic amputee group, P<0.01). The same trend was found for carbon dioxide levels in the skin [mmHg: diabetic amputees, 25 (21-37); controls, 38 (32-42); non-diabetic amputee, 34 (31-39)] (control compared with diabetic amputee, P<0.01; diabetic amputee compared with non-diabetic amputee, P<0.05). Vibration and pressure perception measurements (which assess Abeta nerve fibre function) showed that both the diabetic amputee and non-diabetic amputee subjects had significantly greater impairment than the controls. However, measures of Aalpha and C nerve fibre function were abnormal only in the diabetic amputee group. Thus the peripheral vascular and nerve functions of age-matched diabetic and non-diabetic subjects having undergone lower limb amputation show specific differences, with non-diabetic amputees exhibiting signs of neuropathy. This indicates that factors characteristic of diabetes (such as hyperglycaemia and non-enzymic glycation) are associated with calcification, lower oxygen and carbon dioxide levels in the skin, and abnormal Aalpha and C nerve fibre function.

Role of neuropathy and plasma nitric oxide in recurrent neuropathic and neuroischemic diabetic foot ulcers

Various factors are associated with foot ulceration, including delayed reporting of ulcers, poor glycemic control, and severity of neuropathy. Several studies have looked at the role of nitric oxide in wound healing. However, no studies have examined its role in the occurrence and recurrence of diabetic foot ulceration. In a cross-sectional study we examined the role of neuropathy, retinopathy, nephropathy, and plasma nitric oxide (estimated from plasma nitrite and nitrate) levels in diabetic patients with recurrent and non-recurrent neuropathic and neuroischemic foot ulcers. Patients with recurrent foot ulcers had higher vibration perception threshold values compared to patients with non-recurrent foot ulcers (47.4 +/- 5.7 volts versus 39.5 +/- 10.3 volts respectively, P < 0.05). In addition, subjects with recurrent foot ulcers had significantly higher plasma nitric oxide compared to subjects with non-recurrent foot ulcers (46.9 +/- 6.3 microm/L versus 30.2 +/- 2.4 microm/L respectively, P < 0.01). Multivariate logistic regression analysis adjusted for age, sex, hemoglobin A1c, presence of retinopathy and nephropathy, vibration perception threshold, plasma creatinine, and total nitric oxide, indicated that only vibration perception threshold was independently associated with the presence of an ulcer [odds ratio: 1.26 (1.10-1.46); P <0.001)] and the recurrence of foot ulcers [odds ratio: 1.13 (1.01-1.27); P =0.04)]. This study has shown that although plasma nitric oxide is higher in patients with recurrent neuropathic and neuroischemic foot ulcers, severity of neuropathy was the most important factor associated with the development and recurrence of foot ulcers in diabetic patients.

Peripheral arterial disease in diabetic and nondiabetic patients: a comparison of severity and outcome

OBJECTIVE

The aim of this study was to quantify the distribution of peripheral arterial disease in the diabetic and nondiabetic population attending for angiography and to compare severity and outcome between both groups of patients.

RESEARCH DESIGN AND METHODS

Randomly selected lower-extremity angiograms were examined according to the Bollinger system. Patient demographics and medical history were recorded and case notes were examined to determine which patients later underwent a revascularization procedure or amputation and which patients had died.

RESULTS

A total of 136 arteriograms obtained between 1992 and 1996 were analyzed. The age (mean +/- SD) of the patients was 64.7 +/- 10.8 years. Diabetic patients (43%) and nondiabetic patients were of similar age (63.9 +/- 10.4 vs. 65.3 +/- 11.1 years, P = 0.43), with a similar history of smoking (81.0 vs. 76.9%, P = 0.26), ischemic heart disease (41.4 vs. 37.2%, P = 0.54), and hypercholesterolemia (24.4 vs. 30.8%, P = 0.48). However, there were a greater proportion of hypertensive patients in the diabetic group (63.8 vs. 39.7%, P = 0.006). Diabetic patients had greater severity of arterial disease in the profunda femoris and all arterial segments below the knee (P = 0.02). A greater number of amputations occurred in the diabetic group: diabetic patients were five times more likely to have an amputation (41.4 vs. 11.5%, odds ratio [OR] 5.4, P < 0.0001). Mortality was higher in the diabetic group (51.7 vs. 25.6%, OR 3.1, P = 0.002), and diabetic patients who died were younger at presentation than nondiabetic patients (64.7 +/- 11.4 vs. 71.1 +/- 8.7 years, P = 0.04).

CONCLUSIONS

In patients with peripheral arterial disease, diabetic patients have worse arterial disease and a poorer outcome than nondiabetic patients.

Plantar tissue thickness is related to peak plantar pressure in the high-risk diabetic foot

OBJECTIVE

To investigate the relationship among plantar foot pressure, plantar subcutaneous tissue thickness, severity of neuropathy (vibration perception threshold [VPT]), callus, and BMI in a large group of neuropathic diabetic patients at risk of foot ulceration.

RESEARCH DESIGN AND METHODS

A total of 157 diabetic neuropathic patients (VPT >25 V) without either peripheral vascular or ulcer history were studied. Plantar foot pressure and plantar tissue thickness were measured at each metatarsal head (MTH) using an optical pedobarograph and an ultrasound scanning platform, respectively.

RESULTS

A significant association was observed between peak plantar pressure and plantar tissue thickness at all MTHs (-0.26 < r < -0.61, P < 0.0001), with the least pronounced association at the first MTH. In addition, the pressure time integral was significantly associated with plantar tissue thickness (-0.24 < r < -0.57, P < 0.0001). BMI was significantly related to plantar tissue thickness (0.18 < r < 0.45, P < 0.05), but not to peak forefoot pressures. Subjects with callus had significantly reduced plantar tissue thickness at all MTHs except the first MTH and increased peak pressures at all MTHs (P < 0.001).

CONCLUSIONS

This study confirms a strong inverse relationship between plantar tissue thickness and dynamic foot pressure measurements. Long-term follow-up of this patient population will confirm whether reduced plantar tissue thickness predicts the development of diabetic foot ulcers.

Off-loading the diabetic foot wound: a randomized clinical trial

OBJECTIVE

To compare the effectiveness of total-contact casts (TCCs), removable cast walkers (RCWs), and half-shoes to heal neuropathic foot ulcerations in individuals with diabetes.

RESEARCH DESIGN AND METHODS

In this prospective clinical trial, 63 patients with superficial noninfected, nonischemic diabetic plantar foot ulcers were randomized to one of three off-loading modalities: TCC, half-shoe, or RCW. Outcomes were assessed at wound healing or at 12 weeks, whichever came first. Primary outcome measures included proportion of complete wound healing at 12 weeks and activity (defined as steps per day).

RESULTS

The proportions of healing for patients treated with TCC, RCW, and half-shoe were 89.5, 65.0, and 58.3%, respectively. A significantly higher proportion of patients were healed by 12 weeks in the TCC group when compared with the two other modalities (89.5 vs. 61.4%, P = 0.026, odds ratio 5.4, 95% CI 1.1-26.1). There was also a significant difference in survival distribution (time to healing) between patients treated with a TCC and both an RCW (P = 0.033) and half-shoe (P = 0.012). Patients were significantly less active in the TCC (600.1 +/- 320.0 daily steps) compared with the half-shoe (1,461.8 +/- 1,452.3 daily steps, P = 0.04). There was no significant difference in the average number of steps between the TCC and the RCW (767.6 +/- 563.3 daily steps, P = 0.67) or the RCW and the half-shoe (P = 0.15).

CONCLUSIONS

The TCC seems to heal a higher proportion of wounds in a shorter amount of time than two other widely used off-loading modalities, the RCW and the half-shoe.

Sural nerve fibre pathology in diabetic patients with mild neuropathy: relationship to pain, quantitative sensory testing and peripheral nerve electrophysiology

Nerve fibre pathology is poorly described in diabetic patients with mild neuropathy and has not been adequately related to clinical evaluation, quantitative sensory examination and neurophysiology. Sural nerve myelinated and unmyelinated fibre pathology was morphometrically quantified and related to the presence of pain and conventional measures of neuropathic severity in 15 diabetic patients with mild neuropathy and 14 control subjects. Diabetic patients demonstrated a significant (P < 0.01) reduction in myelinated fibre density, but no change in fibre/axonal area, or g-ratio, compared to control subjects. Unmyelinated fibre degeneration was evidenced by an increase in the percentage of unassociated Schwann cell profiles (P < 0.0001) and a reduction in axon density (P < 0.0008) in diabetic patients. This was associated with a significant reduction in unmyelinated axon diameter (P < 0.001) with a shift of the size frequency distribution to the left (P < 0.02). Neurophysiology, quantitative sensory testing and nerve fibre pathology failed to differentiate diabetic patients with painful and painless neuropathy and failed to correlate with any measure of unmyelinated fibre pathology.

A prospective study of contact lens wear in diabetes mellitus

A prospective, controlled, observer-masked study was conducted to investigate the suitability of contact lenses for patients with diabetes mellitus. Forty diabetic patients and 40 non-diabetic control subjects were fitted with soft hydrogel contact lenses to be worn on a daily wear basis for 12 months. The ocular response was assessed using slit lamp biomicroscopy, ultrasonic pachometry, corneal aesthesiometry and visual acuity measures. Compared to non-diabetic subjects, diabetic patients displayed significantly reduced corneal transparency, variable vision and reduced comfort with the contact lenses (p < 0.05). There were no significant differences between the two groups with respect to ocular hyperaemia, corneal staining, corneal thickness, corneal sensitivity or high contrast visual acuity. Contrary to previous reports, the response of the diabetic eye to contact lenses--as observed clinically--does not differ appreciably from that of the non-diabetic eye. These results suggest that current generation daily wear soft contact lenses can be a viable mode of vision correction for diabetic patients.

A foot care program for diabetic unilateral lower-limb amputees

OBJECTIVE

To assess the efficacy of a specialist foot care program designed to prevent a second amputation and to assess peripheral vascular disease (PVD) and peripheral neuropathy in diabetic unilateral lower-limb amputees.

RESEARCH DESIGN AND METHODS

Investigations were carried out in 143 diabetic lower-limb unilateral amputees referred to a subregional rehabilitation center for prosthetic care from a catchment area of approximately 3 million people. Peripheral vascular and nerve assessment, education, and podiatry were provided for each patient.

RESULTS

For the patients referred to the foot care program, there were no baseline differences between the patients who proceeded to a bilateral amputation (n = 22) and those who remained as unilateral amputees (n = 121) in their level of foot care knowledge and mean neuropathy scores. Mean ankle-brachial pressure index was significantly lower for the bilateral amputees (0.75 +/- 0.04) compared with the unilateral amputees (0.90 +/- 0.03, mean +/- SEM, P < 0.05), but there was no difference in the level of oxygen in the skin. However, the level of carbon dioxide was significantly lower in patients with bilateral amputation (24.21 +/- 2.16 vs. 31.20 +/- 0.85 mmHg, P < 0.03). Overall, the establishment of a specialist foot care program made no impact on contralateral limb amputation (22 of 143, 15.4%) compared with matched patients without the program (21 of 148, 14%) over a 2-year outcome period for each patient.

CONCLUSIONS

PVD is more closely associated with diabetic bilateral amputation than neuropathy or level of foot care knowledge. Preventative foot care programs for diabetic unilateral amputees should therefore place greater emphasis on peripheral vascular assessment to identify patients at risk and on the development of timely intervention strategies.

The effects of ulcer size and site, patient's age, sex and type and duration of diabetes on the outcome of diabetic foot ulcers

AIMS

The outcome of foot ulcers is affected by wound depth, infection, ischaemia and glycaemic control. The aim of this study was to determine the effects of ulcer size, site, patient's age, sex and type and duration of diabetes on the outcome of diabetic foot ulcers.

METHODS

Diabetic patients with new foot ulcers presenting during a 12-month period had demographics and ulcer characteristics recorded at presentation. Ulcers were followed-up until an outcome was noted.

RESULTS

One hundred and ninety-four patients (77% males) with a mean (+/- SD) age and duration of diabetes of 56.6 +/- 12.6 and 15.4 +/- 9.9 years, respectively, were included in the study. The majority of ulcers were neuropathic (67.0%) and present on the forefoot (77.8%) with a median (interquartile range) area of 1.5 (0.6-4.0) cm2. Amputations were performed for 15% of ulcers; 65% healed; 16% remained unhealed and 4% of patients died. The median (95% confidence interval) time to healing was 10 (8.8-11.6) weeks. Ulcer area at presentation was greater in the amputation group compared to healed ulcers (3.9 vs. 1.2 cm2, P < 0.0001). Ulcer area correlated with healing time (rs = 0.27, P < 0.0001) and predicted healing (P = 0.04). Patient's age, sex, duration/type of diabetes, and ulcer site had no effect on outcome.

CONCLUSIONS

Ulcer area, a measure of ulcer size, predicts the outcome of foot ulcers. Its inclusion into a diabetic wound classification system will make that system a better predictor of outcome.

A comparison of two diabetic foot ulcer classification systems: the Wagner and the University of Texas wound classification systems

OBJECTIVE

In this study the following two ulcer classification systems were applied to new foot ulcers to compare them as predictors of outcome: the Wagner (grade) and the University of Texas (LT) (grade and stage) wound classification systems.

RESEARCH DESIGN AND METHODS

Ulcer size, appearance, clinical evidence of infection, ischemia, and neuropathy at presentation were recorded, and patients were followed up until healing or for 6 months.

RESULTS

Of 194 patients with new foot ulcers, 67.0% were neuropathic, 26.3% were neuroischemic, 1.0% were ischemic, and 5.7% had no identified underlying factors. Median (interquartile range [IQR]) ulcer size at presentation was 1.5 cm2 (0.6-4.0). Lower-limb amputations were performed for 15% of ulcers, whereas 65% healed [median (IQR) healing time 5 (3-10) weeks] and 16% were not healed at study termination; 4% of patients died. Wagner grade (P < 0.0001), and UT grade (P < 0.0001) and stage (P < 0.001) showed positive trends with increased number of amputations. For UT stage, the risk of amputation increased with infection both alone (odds ratio [OR] = 11.1, P < 0.0001) and in combination with ischemia (OR = 14.7, P < 0.0001), but not significantly with ischemia alone (OR = 4.6, P = 0.09). Healing times were not significantly different for each grade of the Wagner (P = 0.1) or the UT system (P = 0.07), but there was a significant stepwise increase in healing time with each stage of the UT system (P < 0.05), and stage predicted healing (P < 0.05).

CONCLUSIONS

Increasing stage, regardless of grade, is associated with increased risk of amputation and prolonged ulcer healing time. The UT system's inclusion of stage makes it a better predictor of outcome.