Association of α-Dicarbonyls and Advanced Glycation End Products with Insulin Resistance in Non-Diabetic Young Subjects: A Case-Control Study

Harmful Free Radicals in Aging: A Narrative Review of Their Detrimental Effects on Health

The production of harmful free radicals (H-FRs), especially those with oxygen or nitrogen atoms, depends on both internal and environmental causes. The negative effects of H-FRs are greatly alleviated by antioxidant protection. The harmful impact of oxidative stress, or OS, is brought on by a disparity between the defense mechanisms of the body and the creation of H-FRs. Aging is characterized by a slow decline in tissue and organ competence. Age-mediated pathologies start as an aberrant accumulation of H-FRs, which inhibit cells' capacity to divide, repair, and operate, based on the OS theorem of aging. The natural outcome of this situation is apoptosis. These conditions may include skeletal muscle dysfunction, cancer, cardiovascular, chronic hepatitis, chronic renal, and chronic pulmonary disorders. Given the substantial role that OS plays in the progression of many of these illnesses, antioxidant-based therapy may have a favorable impact on how these diseases progress. To ascertain the true efficacy of this therapy strategy, more research is necessary. The aim of this study is to provide an overview of the literature on this challenging issue that is attracting interest.

Association between hemoglobin A1c and abdominal aortic calcification: results from the National Health and Nutrition Examination Survey 2013-2014

BACKGROUND

Hemoglobin A1c (HbA1c), a "gold standard" for the assessment of glycemic control, was associated with an increased risk of cardiovascular disease and coronary artery calcification. However, its effects on abdominal aortic calcification (AAC) are uncertain. The present study comprehensively investigated the association between HbA1c and AAC in the 2013-2014 National Health and Nutrition Examinations Surveys.

METHODS

Among 1,799 participants ≥ 40 years, dual-energy X-ray absorptiometry-derived AAC was quantified using the Kauppila score (AAC-24). Severe AAC was defined as a total AAC-24 > 6. Weighted linear regression models and logistic regression models were used to determine the effects of HbA1c on AAC. The restricted cubic spline model was used for the dose-response analysis.

RESULTS

The mean AAC-24 of participants was 1.3, and 6.7% of them suffered from severe AAC. Both AAC-24 and the prevalence of severe AAC increased with the higher tertile of HbA1c (P < 0.001). Elevated HbA1c levels would increase the AAC-24 (β = 0.73, 95% CI: 0.30-1.16) and the risk of severe AAC (OR = 1.63, 95% CI: 1.29-2.06), resulting in nearly linear dose-response relationships in all participants. However, this positive correlation were not statistically significant when participants with diabetes were excluded. Furthermore, subgroup analysis showed significant interactions effect between HbA1c and hypertension on severe AAC with the OR (95% CI) of 2.35 (1.62-3.40) for normotensives and 1.39 (1.09-1.79) for hypertensives (P for interaction = 0.022).

CONCLUSION

Controlling HbA1c could reduce AAC scores and the risk of severe AAC. Glycemic management might be a component of strategies for preventing AAC among all participants, especially normotensives.

Glyoxalase I is a novel target for the prevention of metabolic derangement

Obesity prevalence in the US has nearly tripled since 1975 and a parallel increase in prevalence of type 2 diabetes (T2D). Obesity promotes a myriad of metabolic derangements with insulin resistance (IR) being perhaps the most responsible for the development of T2D and other related diseases such as cardiovascular disease. The precarious nature of IR development is such that it provides a valuable target for the prevention of further disease development. However, the mechanisms driving IR are numerous and complex making the development of viable interventions difficult. The development of metabolic derangement in the context of obesity promotes accumulation of reactive metabolites such as the reactive alpha-dicarbonyl methylglyoxal (MG). MG accumulation has long been appreciated as a marker of disease progression in patients with T2D as well as the development of diabetic complications. However, recent evidence suggests that the accumulation of MG occurs with obesity prior to T2D onset and may be a primary driving factor for the development of IR and T2D. Further, emerging evidence also suggests that this accumulation of MG with obesity may be a result in a loss of MG detoxifying capacity of glyoxalase I. In this review, we will discuss the evidence that posits MG accumulation because of GLO1 attenuation is a novel target mechanism of the development of metabolic derangement. In addition, we will also explore the regulation of GLO1 and the strategies that have been investigated so far to target GLO1 regulation for the prevention and treatment of metabolic derangement.

Receptor for the Advanced Glycation End Products (RAGE) Pathway in Adipose Tissue Metabolism

Advanced glycation end products (AGEs) are mediators in the process of cellular dysfunction in response to hyperglycemia. Numerous data indicate that the accumulation of AGEs in the extracellular matrix plays a key role in the development of obesity-related adipose tissue dysfunction. Through binding of their membrane receptor (RAGE), AGEs affect numerous intracellular pathways and impair adipocyte differentiation, metabolism, and secretory activity. Therefore, inhibiting the production and accumulation of AGEs, as well as interfering with the metabolic pathways they activate, may be a promising therapeutic strategy for restoring normal adipose tissue function and, thus, combating obesity-related comorbidities. This narrative review summarizes data on the involvement of the RAGE pathway in adipose tissue dysfunction in obesity and the development of its metabolic complications. The paper begins with a brief review of AGE synthesis and the RAGE signaling pathway. The effect of the RAGE pathway on adipose tissue development and activity is then presented. Next, data from animal and human studies on the involvement of the RAGE pathway in obesity, diabetes, and cardiovascular diseases are summarized. Finally, therapeutic perspectives based on interference with the RAGE pathway are discussed.

Association of Atherogenic Index of Plasma with Cardiometabolic Risk Factors and Markers in Lean 14-to-20-Year-Old Individuals: A Cross-Sectional Study

Cardiometabolic risk factors at a young age pose a significant risk for developing atherosclerotic cardiovascular disease in adulthood. Atherogenic dyslipidemia is highly associated with obesity and metabolic syndrome already in young age. It remains unclear whether cardiometabolic risk factors associate with the atherogenic index of plasma (AIP = log (TAG/HDL-C) in lean subjects with low atherogenic risk. As both the AIP and markers of cardiometabolic risk are continuous variables, we expected their association to be linear before the manifestation of obesity and atherogenic dyslipidemia. We analyzed the prevalence of increased atherogenic risk (AIP ≥ 0.11) in 2012 lean 14-to-20-year-old subjects (55% females) and the trends of cardiometabolic risk factors across the quartiles (Q) of AIP in a subgroup of 1947 (56% females) subjects with low atherogenic risk (AIP < 0.11). The prevalence of AIP ≥ 0.11 reached 3.6% in females and 8.5% in males. HDL-C, non-HDL-C, triglycerides, and the continuous metabolic syndrome score showed a stepwise worsening across the AIP quartiles in both sexes. Measures of obesity and insulin resistance were worse in Q4 vs. Q1 groups, and leukocyte counts were higher in Q4 and Q3 vs. Q1. Females in Q4 presented with a higher C-reactive protein and lower adiponectin, estradiol, and testosterone levels. The multivariate regression model selected non-HDL-C, QUICKI, and erythrocyte counts as significant predictors of AIP in males; and non-HDL-C and C-reactive protein in females. A question arises whether the lean individuals on the upper edge of low atherogenic risk are prone to earlier manifestation of metabolic syndrome and shift to the higher AIP risk group.

Dietary Advanced Glycation End Products: Their Role in the Insulin Resistance of Aging

Insulin resistance (IR) is commonly observed during aging and is at the root of many of the chronic nontransmissible diseases experienced as people grow older. Many factors may play a role in causing IR, but diet is undoubtedly an important one. Whether it is total caloric intake or specific components of the diet, the factors responsible remain to be confirmed. Of the many dietary influences that may play a role in aging-related decreased insulin sensitivity, advanced glycation end products (AGEs) appear particularly important. Herein, we have reviewed in detail in vitro, animal, and human evidence linking dietary AGEs contributing to the bodily burden of AGEs with the development of IR. We conclude that numerous small clinical trials assessing the effect of dietary AGE intake in combination with strong evidence in many animal studies strongly suggest that reducing dietary AGE intake is associated with improved IR in a variety of disease conditions. Reducing AGE content of common foods by simple changes in culinary techniques is a feasible, safe, and easily applicable intervention in both health and disease. Large-scale clinical trials are still needed to provide broader evidence for the deleterious role of dietary AGEs in chronic disease.