Advanced glycation end products assessed by skin autofluorescence: a new marker of diabetic foot ulceration

Cardiac electrophysiology, structure and diastolic function in patients with diabetic foot versus those without diabetic foot

AIMS/INTRODUCTION

To evaluate the differences in cardiac autonomic function, cardiac structure and diastolic function between individuals with diabetic foot (DF) and those with diabetes but without DF.

MATERIALS AND METHODS

A total of 413 individuals with DF and 437 without DF who underwent a 24-h electrocardiogram Holter and a Doppler echocardiogram were included. The heart rate variability parameters to evaluate cardiac autonomic function, and the indices for the assessment of cardiac structure and left ventricular (LV) diastolic function, including left atrium, LV posterior wall thickness, interventricular septum and E/e' ratio, were measured or calculated. Propensity score matching was used for the sensitivity analysis to minimize potential imbalance.

RESULTS

In both the crude and propensity score matching analyses, significant differences were observed in heart rate variability between individuals with and without DF, as evidenced by lower standard deviation of the normal sinus interval, lower low-frequency power/high-frequency power ratio, lower standard deviation of the 5-min average RR intervals, lower low-frequency power, lower percentage of normal adjacent RR interval difference >50 ms, lower root mean square of successive RR interval differences and lower high-frequency power (all P < 0.05). In multivariate analysis, DF showed an independent negative correlation with the aforementioned indices of heart rate variability (all P < 0.05). Individuals with DF showed higher left atrium, LV posterior wall thickness, interventricular septum and a higher E/e' ratio than those without DF in the crude analysis (all P < 0.05), whereas these indices were no longer associated with DF in the multivariate analysis and the propensity score matching analyses.

CONCLUSIONS

Cardiac autonomic modulation was more severely impaired in individuals with DF than in their counterparts without DF. There has been insufficient evidence to demonstrate the independent association of DF and LV diastolic dysfunction.

The skin autofluorescence of advanced glycation end-products relates to the development of foot ulcers in type 2 diabetes: A longitudinal observational study

OBJECTIVES

The long-term glycemic memory contributes to vascular complications in type 2 diabetes, including those patients with Diabetic Foot Ulcers (DFU). We investigated whether the skin autofluorescence (SAF) of Advanced Glycation End-products related to later DFUs.

RESEARCH DESIGN & METHODS

SAF was measured with an AGE-Reader in a retrospective cohort of patients hospitalized from 2009 to 2017 for Type 2 Diabetes. New DFUs were registered until the year 2020 and survival analyses were performed.

RESULTS

The 517 patients (men: 58.0 %), were 62 ± 9 years old at baseline, with a duration of diabetes of 14 ± 10 years, HbA1c: 8.7 ± 1.8 %, complications included 33.8 % macroangiopathies, 44.9 % diabetic kidney diseases and 26.7 % retinopathies. According to the IWGDF classification, the grades of risk for DFU were 0 for 43.2 %, 1 for 23.9 %, 2 for 7.2 %, and 3 for 25.7 %. During the 53 months of follow-up, 58 new DFUs occurred, mostly in patients with SAF higher than its median value (2.65 AU). Adjusted for age and sex, conventional risk factors (duration and control of diabetes, arterial hypertension, dyslipidemia, smoking), and other complications (macroangiopathy, diabetic kidney disease, retinopathy), SAF related to later DFUs. Adjusted for the IWGDF classification, SAF related to new DFUs (HR: 1.81, 95%CI:1.25-2.62). This relationship was significant for the 403 subjects without previous history of DFU (HR: 2.32, 95%CI: 1.36-3.95). SAF did not predict recurrence for patients with a previous history of DFUs.

CONCLUSION

SAF, a simple non-invasive marker of glycemic memory, independently predicts the occurrence of a first foot ulcer in patients with Type 2 Diabetes.

Accumulation of Advanced Glycation End-Products in the Body and Dietary Habits

The formation of advanced glycation end-products (AGE) in tissues is a physiological process; however, excessive production and storage are pathological and lead to inflammation. A sedentary lifestyle, hypercaloric and high-fructose diet and increased intake of processed food elements contribute to excessive production of compounds, which are created in the non-enzymatic multi-stage glycation process. The AGE’s sources can be endogenous and exogenous, mainly due to processing food at high temperatures and low moisture, including grilling, roasting, and frying. Accumulation of AGE increases oxidative stress and initiates various disorders, leading to the progression of atherosclerosis, cardiovascular disease, diabetes and their complications. Inborn defensive mechanisms, recovery systems, and exogenous antioxidants (including polyphenols) protect from excessive AGE accumulation. Additionally, numerous products have anti-glycation properties, occurring mainly in fruits, vegetables, herbs, and spices. It confirms the role of diet in the prevention of civilization diseases.

Advanced Glycation End Products and Their Effect on Vascular Complications in Type 2 Diabetes Mellitus

Diabetes is well established as a chronic disease with a high health burden due to mortality or morbidity from the final outcomes of vascular complications. An increased duration of hyperglycemia is associated with abnormal metabolism. Advanced glycation end products (AGEs) are nonenzymatic glycated forms of free amino acids that lead to abnormal crosslinking of extra-cellular and intracellular proteins by disrupting the normal structure. Furthermore, the interaction of AGEs and their receptors induces several pathways by promoting oxidative stress and inflammation. In this review, we discuss the role of AGEs in diabetic vascular complications, especially type 2 DM, based on recent clinical studies.

Improving Dietary Intake of Essential Nutrients Can Ameliorate Inflammation in Patients with Diabetic Foot Ulcers

Diabetic foot ulcers (DFUs) are classified as chronic wounds and are one of the most common complications of diabetes. In chronic wounds, management of inflammation is a key step in treatment. Nutrition plays an important role in managing and controlling inflammation. This study evaluated the effects of nutrition supplementation and education on inflammatory biomarkers in patients with DFUs. Eligible patients with foot ulcers were randomly assigned to either a treatment (n = 15) or control group (n = 14). Both groups received standard care for wound treatment from the clinic; however, the treatment group was also provided with nutritional supplementation and education. Plasma concentrations of inflammatory biomarkers, namely C-reactive protein (CRP), interleukin 6 (IL6), interleukin 10 (IL10), and tristetraprolin (TTP), were evaluated at baseline and every four weeks, until complete wound closure had occurred or up to 12 weeks. The mean plasma concentration of IL6 significantly decreased in the treatment group (p = 0.001). The interaction between time and group was not statistically significant for the mean plasma concentrations of CRP, IL10, and TTP during the 12 weeks of the study. The results of this study showed the positive effects of nutritional intervention on controlling inflammation in DFU patients. More clinical trials with a larger population and longer duration of time are needed to confirm our results.

Advanced Glycations End Products in the Skin as Biomarkers of Cardiovascular Risk in Type 2 Diabetes

The incidence and prevalence of diabetes are increasing worldwide, and cardiovascular disease (CVD) is the leading cause of death among subjects with type 2 diabetes (T2D). The assessment and stratification of cardiovascular risk in subjects with T2D is a challenge. Advanced glycation end products are heterogeneous molecules produced by non-enzymatic glycation of proteins, lipids, or nucleic acids. Accumulation of advanced glycation end products is increased in subjects with T2D and is considered to be one of the major pathogenic mechanism in developing complications in diabetes. Skin AGEs could be assessed by skin autofluorescence. This method has been validated and related to the presence of micro and macroangiopathy in individuals with type 2 diabetes. In this context, the aim of this review is to critically summarize current knowledge and scientific evidence on the relationship between skin AGEs and CVD in subjects with type 2 diabetes, with a brief reference to other diabetes-related complications.

Clinical Significance of Non-invasive Skin Autofluorescence Measurement in Patients with Diabetes: A Systematic Review and Meta-analysis

BACKGROUND

Advanced glycation end products (AGE), one of the main factors causing diabetic end-organ damage, accumulate in long half-life proteins, such as skin and cartilage collagen. AGE measurement may offer additional evidence to predict diabetic vascular complications. Skin autofluorescence (SAF) is suggested as a non-invasive, quick, and reliable method to measure tissue AGE level. The aim of this study was to review and evaluate evidence on the clinical validation of SAF measurement in diabetes mellitus (DM) patients.

METHODS

In this systematic review and meta-analysis, we searched "PubMed" (MEDLINE) and "Cochrane" databases from their inception to 10 August 2021 for observational studies concerning SAF measurement in diabetic patients. The following key terms were used in advanced searching: "Diabetes", "Diabetes Mellitus"," DM", "Glycation ", "Advanced Glycation End product", "AGE", "skin autofluorescence", "SAF". Published studies that included DM patients and estimated their AGE using SAF were considered eligible for meta-analysis. Articles that were editorials, study proposals, congress posters, or case reports and were not on human subjects were excluded. We used a random-effect models for meta-analyzing the clinical validation of SAF in DM with particular emphasis on chronic diabetes complications.

FINDINGS

We identified 881 records and twenty-nine records fulfilled our eligibility criteria and were included in the systematic review and meta-analysis. A statistically significant correlation was found between SAF and diabetes last HbA1c 0.21(0.13,0.28) in studies with substantial heterogeneity (I2=77.99%, p<0.05). Nevertheless, a significant positive association between SAF level and diabetic retinopathy (DR) [(OR= 1.05, 95% CI=1.03,1.08), (I2=63.78%, p<0.05)], diabetic peripheral neuropathy (DPN) [(OR= 1.11, 95%CI= 1.06,1.16), (I2=79.17%, p<0.05)], diabetic nephropathy (DNP) [(OR= 1.08, 95%CI: 1.05,1.11), (I 2 =65.36%, p<0.05)] and diabetic macrovascular events (D-MVE) [(OR=1.08, 95%CI=1.05,1.11) (I2=67.32, p<0.05)] were found.

INTERPRETATION

Our study confirmed the significance of SAF measurement as a non-invasive surrogate marker of DM micro and macrovascular complications. Skin AGE estimation may be a useful factor for the prediction and early detection of irreversible DM complications. More studies with larger populations and longer follow-up periods are required.

Skin Autofluorescence as a Novel and Noninvasive Technology for Advanced Glycation End Products in Diabetic Foot Ulcers: A Systematic Review and Meta-analysis

OBJECTIVE

Skin autofluorescence (SAF) has been suggested as a novel and noninvasive technique for assessing tissue accumulation of advanced glycation end products in diabetes and related complications. The aim of this systematic review and meta-analysis was to evaluate the use of SAF in diabetic foot ulcers (DFUs).

DATA SOURCES

PubMed/MEDLINE and other digital databases.

STUDY SELECTION

The authors included studies comparing the SAF levels in patients with DFU with a non-DFU group to determine its association with DFU risk.

DATA EXTRACTION

Collected data included the SAF method and its values in DFU and non-DFU groups, covariates used in adjustment along with the unadjusted and/or multivariate adjusted odds ratios (ORs) for the association of SAF with DFU risk, and other study characteristics.

DATA SYNTHESIS

A total of six studies were included in this meta-analysis. Five studies that involved 611 participants were included to compare SAF methods. Compared with the non-DFU group, the DFU group showed a significantly increased level of SAF (standardized mean difference, 0.67; 95% confidence interval [CI], 0.32-1.01; P < .001). The results of meta-analysis of ORs revealed that the increased SAF level was independently associated with increased DFU risk in both unadjusted (OR, 3.16; 95% CI, 2.18-4.57; P < .001) and adjusted models (OR, 3.07; 95% CI, 1.95-4.81; P < .001).

CONCLUSIONS

These findings suggest that SAF could be useful as a novel and noninvasive technology to help determine DFU risk. However, further studies establishing its diagnostic and prognostic utilities are needed.

Demonstration of advanced glycation end product (AGE) expression in bladder cancer tissue in type-2 diabetic and non-diabetic patients and the relationship between AGE accumulation and endoplasmic reticulum stress with bladder cancer

PURPOSE

This study aimed to investigate the relationship between advanced glycation end product (AGE) expression and accumulation in transurethral resection (TUR-B) material taken from type-2 diabetes mellitus (DM) and non-DM bladder cancer patients and endoplasmic reticulum stress (ERS) with bladder cancer.

METHOD

The patients who had TUR-B between May 2016 and September 2018 were included in the study. After the tissue samples had been taken and frozen at -80°C, they were homogenised to be used in enzyme-linked immunosorbent assay (ELISA) experiments. The patients were grouped as DM and non-DM. In both groups, mean AGE, IRE1, PERK and ATF6 expression amounts were evaluated through ELISA method in the pathological material.

RESULTS

The expression amounts in tissue samples were AGE 0.59 ± 0.03 µg/mL, ATF6 1.08 ± 0.11 µg/mL, IRE1 30.71 ± 1.68 ng/mL, PERK 0.28 ± 0.02 ng. It was /mL. While there was no significant difference amongst AGE µg/mL (P = .146), ATF6 µg/mL (P = .175), IRE1 ng/mL (P = NA) and PERK ng/mL (P = .125) (P > .05) in the presence of DM, a positive correlation was observed between AGE values and PERK ng/mL values (r = .629; P < .05).

CONCLUSION

Bladder cancer may develop as a result of accumulation of AGEs and ERS. Demonstration of the expression of proteins resulting from AGEs and ERS may be useful biomarkers for the diagnosis, prognosis, prevention and development of treatment alternatives for bladder cancer.

Advanced Glycation End Products: New Clinical and Molecular Perspectives

Diabetes mellitus (DM) is considered one of the most massive epidemics of the twenty-first century due to its high mortality rates caused mainly due to its complications; therefore, the early identification of such complications becomes a race against time to establish a prompt diagnosis. The research of complications of DM over the years has allowed the development of numerous alternatives for diagnosis. Among these emerge the quantification of advanced glycation end products (AGEs) given their increased levels due to chronic hyperglycemia, while also being related to the induction of different stress-associated cellular responses and proinflammatory mechanisms involved in the progression of chronic complications of DM. Additionally, the investigation for more valuable and safe techniques has led to developing a newer, noninvasive, and effective tool, termed skin fluorescence (SAF). Hence, this study aimed to establish an update about the molecular mechanisms induced by AGEs during the evolution of chronic complications of DM and describe the newer measurement techniques available, highlighting SAF as a possible tool to measure the risk of developing DM chronic complications.

For diabetic type 1 patients, the skin autofluorescence predicts ulcers and amputations

We searched whether the accumulation of Advanced Glycation End-products (AGEs), reflected by the skin autofluorescence (SAF), could predict diabetic foot ulcers (DFUs) during the long-term follow-up of people with type 1 diabetes. During year 2009, we measured the SAF with an AGE-Reader in 206 subjects with type 1 diabetes. DFU and amputations were registered during the 10 following years. The relation between the SAF and later DFU was analyzed by Cox model regression, adjusted for vascular risk factors. The 206 participants were mainly men (55.8%), 51 ± 15 years old, with a 22 ± 13 years diabetes duration. Twelve subjects presented a DFU. Their SAF were higher: 2.61 ± 0.89 AU vs 2.11 ± 0.53 for the others (p = 0.003), related to the risk of DFU (OR:3.69; 95% CI: 1.06-12.79) after adjustment for age, gender, diabetes duration, initial HbA1c, arterial hypertension, history of smoking, blood lipids and use of a statin. Five subjects were amputated, also related to the initial SAF: OR: 11.28 (95% CI: 1.76-79.97) after adjustment for age, gender, duration of diabetes, and HbA1c. The SAF has already been related to diabetic neuropathy and peripheral arterial disease. It predicts DFU in type 1 diabetes, which suggests that AGEs play a role in this highly specific and feared complication.

Skin AGEs and diabetic neuropathy

Advanced glycation end-products (AGEs) are heterogeneous molecules produced by the non-enzymatic glycation of proteins, lipids, or nucleic acids during hyperglycaemia. Accumulation of AGEs in the peripheral nerves has recently been proposed as an additional risk factor for the development of diabetic neuropathy (DN). The gold standard for measurement of tissue-bound AGEs is tissue biopsy. However, their assessment with the newer, fast and simple method of skin autofluorescence (sAF) has recently gained special interest by virtue of its non-invasive, highly reproducible nature and its acceptable correlation with the reference method of skin biopsy. Accumulation of tissue AGEs evaluated by sAF has been shown to independently correlate with DN. Importantly, increasing evidence underscores their potential value as early biomarkers of the latter. Further important associations include diabetic nephropathy, diabetic retinopathy and cardiovascular autonomic neuropathy. However, the value of the implementation of screening with skin AGEs for DN remains unclear. The aim of the present review is to critically summarise current evidence on the association between skin AGEs and diabetic microvascular complications, with a particular emphasis on diabetic neuropathy, and to note the most important limitations of existing knowledge. Longer follow-up studies are also highly anticipated to clarify its role and provide data on patient selection and cost-effectiveness.

Skin Advanced Glycation End Products among Subjects with Type 2 Diabetes Mellitus with or without Distal Sensorimotor Polyneuropathy

MATERIALS AND METHODS

We included 132 subjects (88 men) with a mean age of 64.57 years and median T2DM duration of 14.5 years. Skin AGEs were measured with AGE reader mu connect (Diagnoptics) on the dominant arm. The device enables single and automated triplicate measurements: both of these were performed. DSPN was diagnosed through the neuropathy disability score (NDS). Small nerve fibre function was assessed by temperature and pinprick sensation on the foot. Bilateral measurement of the vibration perception threshold (VPT) on the hallux was carried out by using a neurothesiometer (Horwell Scientific Laboratory Supplies).

RESULTS

Single and triplicate AGE measurements were positively correlated with each other (Pearson's correlation coefficient r = 0.991, 95%CI = 0.987-0.994, p < 0.001). AGEs were higher among subjects with vs. those without DSPN (p < 0.001). Furthermore, they were higher among subjects with reduced vs. normal temperature sensation (p < 0.001), among subjects with reduced vs. normal pinprick sensation (p = 0.002), among those with abnormal vs. normal monofilament examination (p < 0.001), and among those with abnormal vs. normal VPT (p < 0.001). AGEs were correlated with NDS, VPT, and monofilament score.

CONCLUSIONS

In T2DM, skin AGEs are increased in the presence of DSPN. This holds true both for large and for small nerve function impairment. Moreover, AGEs are correlated with DSPN severity.

Is skin autofluorescence (SAF) representative of dermal advanced glycation endproducts (AGEs) in dark skin? A pilot study

Aims

Non-invasively assessed skin autofluorescence (SAF) measures advanced glycation endproducts (AGEs) in the dermis. SAF correlates with dermal AGEs in Caucasians and Asians, but studies in dark-skinned subjects are lacking. In this pilot we aimed to assess whether SAF signal is representative of intrinsic fluorescence (IF) and AGE accumulation in dark skin.

Methods

Skin biopsies were obtained in 12 dark-skinned subjects (6 healthy subjects, median age 22 years; 6 diabetes mellitus (DM) subjects, 65 years). SAF was measured with the AGE Reader, IF using confocal microscopy, and AGE distribution with specific antibodies. CML and MG-H1 were quantified with UPLC-MS/MS and pentosidine with HPLC and fluorescent detection.

Results

SAF correlated with IF from the dermis (405nm, r = 0.58, p < 0.05), but not with CML (r = 0.54, p = 0.07). CML correlated with IF from the dermis (405nm, r = 0.90, p < 0.01). UV reflectance and the coefficient of variation of SAF were negatively correlated (r = -0.80, p < 0.01). CML and MG-H1 were predominantly present around blood vessels, in collagen and fibroblasts in the dermis.

Conclusion

This proof of concept study is the first to compare non-invasive SAF with AGE levels measured in skin biopsies in dark-skinned subjects. SAF did not correlate with individual AGEs from biopsies, but was associated with IF. However, the intra-individual variance was high, limiting its application in dark-skinned subjects on an individual basis.

Skin autofluorescence, a marker of glucose memory in type 2 diabetes

Abstract

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The accumulation of Advanced Glycation End-products in the tissues studied as a marker of metabolic memory.

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Skin autofluorescence as a marker of glycemic memory in type 2 diabetes.

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Skin autofluorescence was independently related to their most ancient HbA1c.

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Skin autofluorescence was higher in subjects with microangiopathic complications.

Within- and Between-Body-Site Agreement of Skin Autofluorescence Measurements in People With and Without Diabetes-Related Foot Disease

BACKGROUND

Skin autofluorescence has been used to assess longer term glycemic control and risk of complications. There is however no agreed site at which autofluorescence should be measured. This study evaluated the within- and between-site agreement in measurement of skin autofluorescence using a noninvasive advanced glycation end product (AGE) reader.

METHODS

Overall, 132 participants were included: 16 with diabetes-related foot ulcers (DFU), 63 with diabetes but without foot ulcers (DMC), 53 without diabetes or foot ulcers (HC). Skin autofluorescence was measured using the AGE Reader (DiagnOptics technologies BV, the Netherlands). Three consecutive skin autofluorescence measurements were each performed at six different body sites: the volar surfaces of both forearms (arms), dorsal surfaces of both calves (legs), and plantar surfaces of both feet (feet). Within- and between-site agreements were analyzed with concordance correlation coefficients (CCC) and 95% confidence intervals (95% CI), absolute mean differences (±standard deviation), and Bland-Altman limits of agreement.

RESULTS

The agreement between repeat assessments at the same site was almost perfect (CCC [95% CI] ranging from 0.94 [0.91-0.96] for assessments in the right foot to 0.99 [0.99-0.99] for assessments in the left arm). The limits of agreement were narrow within ±0.5 arbitrary units for all sites. The between-site agreement in measurements was poor (CCC < 0.65) with large maximum absolute mean differences (±SD) in arbitrary units (DFU = 3.40 [±2.04]; DMC = 3.15 [±2.45]; HC = 2.72 [±1.83]) and wide limits of agreement.

CONCLUSIONS

Skin autofluorescence measurements can be repeated at the same site with adequate repeatability but measurements at different sites in the same patient have marked differences. The reason for this variation across sites and whether this has any role in diabetes-related complications needs further investigation.

The role of advanced glycation end-products in the development of coronary artery disease in patients with and without diabetes mellitus: a review

Background

Traditional risk factors are insufficient to explain all cases of coronary artery disease (CAD) in patients with diabetes mellitus (DM). Advanced glycation end-products (AGEs) and their receptors may play important roles in the development and progression of CAD.

Body

Hyperglycemia is the hallmark feature of DM. An increase in the incidence of both micro-and macrovascular complications of diabetes has been observed with increased duration of hyperglycemia. This association persists even after glycemic control has been achieved, suggesting an innate mechanism of “metabolic memory.” AGEs are glycated proteins that may serve as mediators of metabolic memory due to their increased production in the setting of hyperglycemia and generally slow turnover. Elevated AGE levels can lead to abnormal cross linking of extracellular and intracellular proteins disrupting their normal structure and function. Furthermore, activation of AGE receptors can induce complex signaling pathways leading to increased inflammation, oxidative stress, enhanced calcium deposition, and increased vascular smooth muscle apoptosis, contributing to the development of atherosclerosis. Through these mechanisms, AGEs may be important mediators of the development of CAD. However, clinical studies regarding the role of AGEs and their receptors in advancing CAD are limited, with contradictory results.

Conclusion

AGEs and their receptors may be useful biomarkers for the presence and severity of CAD. Further studies are needed to evaluate the utility of circulating and tissue AGE levels in identifying asymptomatic patients at risk for CAD or to identify patients who may benefit from invasive intervention.

Tissue intrinsic fluorescence recovering by an empirical approach based on the PSO algorithm and its application in type 2 diabetes screening

In order to reduce the influence of scattering and absorption on tissue fluorescence spectra, after tissue fluorescence and diffuse reflectance in different tissue optical properties were simulated by the Monte Carlo method, a tissue intrinsic fluorescence recovering algorithm making use of diffuse reflectance spectrum was developed. The empirical parameters in the tissue intrinsic fluorescence recovering algorithm were coded as a particle in the solution domain, the classification performance was defined as the fitness, and then a particle swarm optimization (PSO) algorithm was established for empirical parameters optimization. The skin autofluorescence and diffuse reflectance spectra of 327 subjects were collected in Anhui Provincial Hospital. The skin intrinsic autofluorescence spectra were recovered by using the empirical approach and the integration area of the spectra were calculated as fluorescence intensity. Receiver operating characteristic (ROC) analysis for fluorescence intensity was applied to evaluate the classification performance in type 2 diabetes screening. In addition, a support vector machine (SVM) method was implemented to improve the performance of the classification. The results showed that the sensitivity and specificity were 32% and 76% respectively, and the area under the curve was 0.54 before recovering, while the sensitivity and specificity were 72% and 86% respectively, and the area under the curve was 0.86 after recovering. Furthermore, the sensitivity and specificity increased to 83% and 86% respectively when using linear SVM while 84% and 88%, respectively, when using nonlinear SVM. The results indicate that using the tissue fluorescence spectrum recovery algorithm based on PSO can improve the application of tissue fluorescence spectroscopy effectively.

Ethnicity and skin autofluorescence-based risk-engines for cardiovascular disease and diabetes mellitus

Skin auto fluorescence (SAF) is used as a proxy for the accumulation of advanced glycation end products (AGEs) and has been proposed to stratify patients into cardiovascular disease (CVD) and diabetes mellitus (DM) risk groups. This study evaluates the effects of seven different ethnicities (Arab, Central-East African, Eastern Mediterranean, European, North African, South Asian and Southeast Asian) and gender on SAF as well as validating SAF assessment as a risk estimation tool for CVD and DM in an Arabian cohort. SAF data from self-reported healthy 2,780 individuals, collated from three independent studies, has been linear modelled using age and gender as a covariate. A cross-study harmonized effect size (Cohens’d) is provided for each ethnicity. Furthermore, new data has been collected from a clinically well-defined patient group of 235 individuals, to evaluate SAF as a clinical tool for DM and CVD-risk estimation in an Arab cohort. In an Arab population, SAF-based CVD and/or DM risk-estimation can be improved by referencing to ethnicity and gender-specific SAF values. Highest SAF values were observed for the North African population, followed by East Mediterranean, Arab, South Asian and European populations. The South Asian population had a slightly steeper slope in SAF values with age compared to other ethnic groups. All ethnic groups except Europeans showed a significant gender effect. When compared with a European group, effect size was highest for Eastern Mediterranean group and lowest for South Asian group. The Central-East African and Southeast Asian ethnicity matched closest to the Arab and Eastern Mediterranean ethnicities, respectively. Ethnic and gender-specific data improves performance in SAF-based CVD and DM risk estimation. The provided harmonized effect size allows a direct comparison of SAF in different ethnicities. For the first time, gender differences in SAF are described for North African and East Mediterranean populations.

Autofluorescence of collagen fibres in scar

BACKGROUND/PURPOSE

Autofluorescence has become an important factor associated with diagnosis and treatment of many diseases.

METHODS

Full thickness skin grafts and scar biopsies were obtained from five volunteers. The normal skin or scar tissue paraffin-wax sections were stained with HE and the autofluorescence of collagen fibres was viewed under fluorescence microscopy.

RESULTS

In normal skin, the autofluorescence was showed in dermis, specifically in collagen fibres. There was very weak autofluorescence in epidermis. The spectrum was excited at 488 nm and the peak value of autofluorescence was significantly different between reticular layer (169.24±9.18) and papillar layer of dermis (103.91±15.23). In scar tissue, the autofluorescence was showed in collagen fibres and the peak value was 176.71±20.69. The structure of collagen fibres in normal skin or scar tissue was different in loose degree, thickness, boundle size, and morphology by their autofluorescence.

CONCLUSION

The different peak value of autofluorescence between scar and normal skin may due to the different density of collagen fibtes in them. This study may provide us a simple and effective assessment indicator and method for diagnosis and treatment of scar.

Skin autofluorescence and peripheral neuropathy four years later in type 1 diabetes

OBJECTIVE

Advanced glycation end products (AGEs) are involved in diabetes complications. We aimed to investigate whether the accumulation of AGEs measured by skin autofluorescence (sAF) was associated with signs of diabetic peripheral neuropathy and to sensitivity, pain, motor and autonomic function 4 years later in patients with type 1 diabetes.

METHODS

At baseline, 188 patients (age 51 years, diabetes duration 22 years) underwent skin autofluorescence measurement using the AGE Reader. Four years later, signs of diabetic peripheral neuropathy were defined as the presence of neuropathic pain and/or feet sensory loss or foot ulceration. Neurological tests were systematically performed: vibration perception threshold by neuroesthesiometry, neuropathic pain by the Douleur Neuropathique en 4 Questions score, muscle strength by dynamometry and electrochemical skin conductance. Multivariate analyses were adjusted by age, sex, height, body mass index, tobacco, HbA_1c , diabetes duration, estimated glomerular filtration rate and albumin excretion rate.

RESULTS

At the 4-year follow-up, 13.8% of patients had signs of diabetic peripheral neuropathy. The baseline sAF was higher in those with signs of diabetic peripheral neuropathy (2.5 ± 0.7 vs 2.1 ± 0.5 arbitrary units (AU), p < 0.0005). In the multivariate analysis, a 1 SD higher skin autofluorescence at baseline was associated with an increased risk of signs of neuropathy (OR = 2.68, p = 0.01). All of the neurological tests were significantly altered in the highest quartile of the baseline sAF (>2.4 AU) compared with the lowest quartiles after multivariate adjustment.

CONCLUSION

This non-invasive measurement of skin autofluorescence may have a value for diabetic peripheral neuropathy in type 1 diabetes and a potential clinical utility for detection of diabetic peripheral neuropathy. Copyright © 2016 John Wiley & Sons, Ltd.

Association of Advanced Glycation End Products with coronary Artery Calcification in Japanese Subjects with Type 2 Diabetes as Assessed by Skin Autofluorescence

AIM

Advanced glycation end products (AGE) are considered to be among the critical pathogenic factors involved in the progression of diabetic complications. Skin autofluorescence (AF), a noninvasive measurement of AGE accumulation, has been recognized as a useful and convenient marker for diabetic vascular diseases in Caucasians. This study aimed to evaluate the association of tissue AGE, assessed using skin AF, with coronary artery calcification in Japanese subjects with type 2 diabetes.

METHODS

In total, 122 Japanese subjects with type 2 diabetes enrolled in this cross-sectional study underwent multi-slice computed tomography for total coronary artery calcium scores (CACS) estimation and examination with a skin AF reader.

RESULTS

Skin AF positively correlated with age, sex, diabetes duration, pulse wave velocity, systolic blood pressure, serum creatinine, and CACS. In addition, skin AF results negatively correlated with BMI, eGFR, and serum C-peptide concentration. According to multivariate analysis, age and systolic blood pressure showed strong positive correlation and eGFR showed negative correlation with skin AF values. Multiple linear regression analyses revealed a significant positive correlation between skin AF values and logCACS, independent of age, sex, diabetes duration, HbA1c, BMI, IMT, and blood pressure. However, skin AF showed no association with serum levels of AGE, such as Nε-(carboxymethyl) lysine and 3-deoxyglucosone.

CONCLUSION

Skin AF results positively correlated with CACS in Japanese subjects with type 2 diabetes. This result indicates that AGE plays a role in the pathogenesis of diabetic macrovascular disease. Measurement of skin AF values may be useful for assessing the severity of diabetic complications in Japanese subjects.

Lower-extremity arterial revascularization: Is there any evidence for diabetic foot ulcer-healing?

The presence of peripheral arterial disease (PAD) is an important consideration in the management of diabetic foot ulcers. Indeed, arteriopathy is a major factor in delayed healing and the increased risk of amputation. Revascularization is commonly performed in patients with critical limb ischaemia (CLI) and diabetic foot ulcer (DFU), but also in patients with less severe arteriopathy. The ulcer-healing rate obtained after revascularization ranges from 46% to 91% at 1 year and appears to be improved compared to patients without revascularization. However, in those studies, healing was often a secondary criterion, and there was no description of the initial wound or its management. Furthermore, specific alterations associated with diabetes, such as microcirculation disorders, abnormal angiogenesis and glycation of proteins, can alter healing and the benefits of revascularization. In this review, critical assessment of data from the literature was performed on the relationship between PAD, revascularization and healing of DFUs. Also, the impact of diabetes on the effectiveness of revascularization was analyzed and potential new therapeutic targets described.

A new gender-specific model for skin autofluorescence risk stratification

Advanced glycation endproducts (AGEs) are believed to play a significant role in the pathophysiology of a variety of diseases including diabetes and cardiovascular diseases. Non-invasive skin autofluorescence (SAF) measurement serves as a proxy for tissue accumulation of AGEs. We assessed reference SAF and skin reflectance (SR) values in a Saudi population (n = 1,999) and evaluated the existing risk stratification scale. The mean SAF of the study cohort was 2.06 (SD = 0.57) arbitrary units (AU), which is considerably higher than the values reported for other populations. We show a previously unreported and significant difference in SAF values between men and women, with median (range) values of 1.77 AU (0.79-4.84 AU) and 2.20 AU (0.75-4.59 AU) respectively (p-value « 0.01). Age, presence of diabetes and BMI were the most influential variables in determining SAF values in men, whilst in female participants, SR was also highly correlated with SAF. Diabetes, hypertension and obesity all showed strong association with SAF, particularly when gender differences were taken into account. We propose an adjusted, gender-specific disease risk stratification scheme for Middle Eastern populations. SAF is a potentially valuable clinical screening tool for cardiovascular risk assessment but risk scores should take gender and ethnicity into consideration for accurate diagnosis.

The association between skin autofluorescence and vascular complications in Chinese patients with diabetic foot ulcer: an observational study done in Shanghai

The tissue accumulation of advanced glycation end products (AGEs) can be noninvasively assessed as skin autofluorescence (SAF) by the AGE Reader(TM) device. We aimed to detect the association between SAF and diabetes-associated vascular complications in diabetic foot ulcer (DFU) patients engaged in this study. This cross-sectional survey consisted of 118 consecutive hospitalized diabetic foot patients. The diabetic microvascular (retinopathy, nephropathy, and neuropathy) and macrovascular referring to coronary heart disease (CHD), cerebrovascular disease (CVD), or peripheral artery disease (PAD) complications were evaluated, and then they were divided into different subgroups based on the assessment of vascular complications. As seen from the results, the mean SAF value was 2.8 ± 0.2 AU. SAF was significantly associated with diabetes duration and blood urea nitrogen (R(2) = 62.8%; P < .01). Moreover, in logistic regression analysis, SAF was significantly associated with retinopathy (odds ratio [OR] = 40.11), nephropathy (OR = 8.44), CHD (OR = 44.31), CVD (OR = 80.73), and PAD (OR = 5.98 × 10(9)). In conclusion, SAF, reflecting tissue accumulation of AGEs, is independently associated with the presence of vascular complications in DFU patients.