Increased skin autofluorescence after colorectal operation reflects surgical stress and postoperative outcome

Usefulness of Skin Autofluorescence as a Biomarker of Acute Oxidative Stress in Young Male Japanese Long-Distance Runners: A Cross-Sectional Study

Chronic oxidative stress in long-distance runners adversely affects conditioning. It is important to objectively assess and monitor oxidative stress, but measuring oxidative stress can be invasive or require skill to measure. Therefore, this study aimed to verify whether skin autofluorescence (SAF), a non-invasive, rapid, and easily calculable metric for calculating advanced glycation end products (AGEs), is useful as an oxidative stress biomarker. The subjects were 50 young Japanese male long-distance runners (aged 20.2 ± 1.2 years); 35 average-sized male university students (aged 19.8 ± 1.1 years) served as controls. The interactions and relationships between SAF and plasma pentosidine and oxidative stress markers (reactive oxygen metabolite-derived compounds [d-ROMs], biological antioxidant potential [BAP], and the BAP/d-ROMs ratio) in runners were examined, and SAF in the runners and controls was compared. The results suggest that plasma pentosidine in runners is associated with oxidative stress markers and that it can assess oxidative stress. However, as SAF was not associated with oxidative stress markers, it was not validated as one. In future, clarifying the factors affecting SAF may also clarify the relationship between SAF, plasma pentosidine, and oxidative stress markers.

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.

The AGE Reader: A non-invasive method to assess long-term tissue damage

AIMS

Advanced glycation endproducts (AGEs) are sugar-modified adducts which arise during non-enzymatic glycoxidative stress. These compounds may become systemically elevated in disease states, and accumulate in tissue, especially on long-lived proteins. AGEs have been implicated in various acute, and chronic diseases, stressing the need for reliable and comprehensive measuring techniques. Measurement of AGEs in tissue such as skin requires invasive skin biopsies. The AGE Reader has been developed to assess skin autofluorescence (SAF) non-invasively using the fluorescent properties of several AGEs.

RESULTS/CONCLUSION

Various studies have shown that SAF is a useful marker of disease processes associated with oxidative stress. It is prospectively associated with the development of cardiovascular events in patients with diabetes, renal or cardiovascular disease, and it predicts diabetes, cardiovascular disease, and mortality in the general population. However, when measuring SAF in individual subjects, several factors may limit the reliability of the measurement. These include endogenous factors present in the skin that absorb emission light such as melanin in dark-skinned subjects, but also factors that lead to temporal changes in SAF such as acute diseases and strenuous physical exercise associated with glycoxidative stress. Also, exogenous factors could potentially influence SAF levels inadvertently such as nutrition, and for example the application of skin care products. This review will address the AGE Reader functionality and the endogenous, and exogenous factors which potentially influence the SAF assessment in individual subjects.

Recent Advances and the Potential for Clinical Use of Autofluorescence Detection of Extra-Ophthalmic Tissues

The autofluorescence (AF) characteristics of endogenous fluorophores allow the label-free assessment and visualization of cells and tissues of the human body. While AF imaging (AFI) is well-established in ophthalmology, its clinical applications are steadily expanding to other disciplines. This review summarizes clinical advances of AF techniques published during the past decade. A systematic search of the MEDLINE database and Cochrane Library databases was performed to identify clinical AF studies in extra-ophthalmic tissues. In total, 1097 articles were identified, of which 113 from internal medicine, surgery, oral medicine, and dermatology were reviewed. While comparable technological standards exist in diabetology and cardiology, in all other disciplines, comparability between studies is limited due to the number of differing AF techniques and non-standardized imaging and data analysis. Clear evidence was found for skin AF as a surrogate for blood glucose homeostasis or cardiovascular risk grading. In thyroid surgery, foremost, less experienced surgeons may benefit from the AF-guided intraoperative separation of parathyroid from thyroid tissue. There is a growing interest in AF techniques in clinical disciplines, and promising advances have been made during the past decade. However, further research and development are mandatory to overcome the existing limitations and to maximize the clinical benefits.

Effect of glycation inhibitors on aging and age-related diseases

Vast evidence supports the view that glycation of proteins is one of the main factors contributing to aging and is an important element of etiopathology of age-related diseases, especially type 2 diabetes mellitus, cataract and neurodegenerative diseases. Counteracting glycation can therefore be a means of increasing both the lifespan and healthspan. In this review, accumulation of glycation products during aging is presented, pathophysiological effects of glycation are discussed and ways of attenuation of the effects of glycation are described, concentrating on prevention of glycation. The effects of glycation and glycation inhibitors on the course of selected age-related diseases, such as Alzheimer's disease, Parkinson's disease and cataract are also reviewed.

Clinical assessment of peripheral perfusion to predict postoperative complications after major abdominal surgery early: a prospective observational study in adults

INTRODUCTION

Altered peripheral perfusion is strongly associated with poor outcome in critically ill patients. We wanted to determine whether repeated assessments of peripheral perfusion during the days following surgery could help to early identify patients that are more likely to develop postoperative complications.

METHODS

Haemodynamic measurements and peripheral perfusion parameters were collected one day prior to surgery, directly after surgery (D0) and on the first (D1), second (D2) and third (D3) postoperative days. Peripheral perfusion assessment consisted of capillary refill time (CRT), peripheral perfusion index (PPI) and forearm-to-fingertip skin temperature gradient (T(skin-diff)). Generalized linear mixed models were used to predict severe complications within ten days after surgery based on Clavien-Dindo classification.

RESULTS

We prospectively followed 137 consecutive patients, from among whom 111 were included in the analysis. Severe complications were observed in 19 patients (17.0%). Postoperatively, peripheral perfusion parameters were significantly altered in patients who subsequently developed severe complications compared to those who did not, and these parameters persisted over time. CRT was altered at D0, and PPI and T(skin-diff) were altered on D1 and D2, respectively. Among the different peripheral perfusion parameters, the diagnostic accuracy in predicting severe postoperative complications was highest for CRT on D2 (area under the receiver operating characteristic curve = 0.91 (95% confidence interval (CI) = 0.83 to 0.92)) with a sensitivity of 0.79 (95% CI = 0.54 to 0.94) and a specificity of 0.93 (95% CI = 0.86 to 0.97). Generalized mixed-model analysis demonstrated that abnormal peripheral perfusion on D2 and D3 was an independent predictor of severe postoperative complications (D2 odds ratio (OR) = 8.4, 95% CI = 2.7 to 25.9; D2 OR = 6.4, 95% CI = 2.1 to 19.6).

CONCLUSIONS

In a group of patients assessed following major abdominal surgery, peripheral perfusion alterations were associated with the development of severe complications independently of systemic haemodynamics. Further research is needed to confirm these findings and to explore in more detail the effects of peripheral perfusion-targeted resuscitation following major abdominal surgery.

Fluorescence imaging in surgery

Although the modern surgical era is highlighted by multiple technological advances and innovations, one area that has remained constant is the dependence of the surgeon's vision on white-light reflectance. This renders different body tissues in a limited palette of various shades of pink and red, thereby limiting the visual contrast available to the operating surgeon. Healthy tissue, anatomic variations, and diseased states are seen as slight discolorations relative to each other and differences are inherently limited in dynamic range. In the upcoming years, surgery will undergo a paradigm shift with the use of targeted fluorescence imaging probes aimed at augmenting the surgical armamentarium by expanding the "visible" spectrum available to surgeons. Such fluorescent "smart probes" will provide real-time, intraoperative, pseudo-color, high-contrast delineation of both normal and pathologic tissues. Fluorescent surgical molecular guidance promises another major leap forward to improve patient safety and clinical outcomes, and to reduce overall healthcare costs. This review provides an overview of current and future surgical applications of fluorescence imaging in diseased and nondiseased tissues and focus on the innovative fields of image processing and instrumentation.