Oxidative stress in insulin-resistant conditions: cardiovascular implications

Maternal metabolic syndrome in pregnancy and child development at age 5: exploring mediating mechanisms using cord blood markers

BACKGROUND

There is limited evidence on how the classification of maternal metabolic syndrome during pregnancy affects children's developmental outcomes and the possible mediators of this association. This study uses a cohort sample of 12,644 to 13,832 mother-child pairs from the UK Born in Bradford Study to examine the associations between maternal metabolic syndrome classification (MetS) and child development outcomes at age 5, using cord blood markers as candidate mediators.

METHODS

Maternal cardiometabolic markers included diabetes, obesity, triglycerides, high-density lipoprotein cholesterol, blood pressure, hypertension, and fasting glucose during pregnancy. Cord blood markers of high-density lipoprotein cholesterol, low-density lipoprotein cholesterol, triglycerides, leptin, and adiponectin were used as child mediators. Child outcomes included two starting school variables: British Picture Vocabulary Scale (BPVS) and the Letter Identification Assessment (LID), and five developmental milestone domains from a national UK framework: (1) communication and language (COM); (2) personal, social, and emotional (PSE); (3) physical development (PHY); (4) literacy (LIT); and (5) mathematics (MAT). Mediation models were used to examine the associations between the classification of maternal metabolic syndrome and child developmental milestones. Models were adjusted for potential maternal, socioeconomic, and child confounders such as maternal education, deprivation, and gestational age.

RESULTS

In mediation models, significant total effects were found for MetS associations with children's development in the LIT domain at age 5. MetS predicted individual cord blood mediators of lower HDL and increased leptin levels in both adjusted and unadjusted models. Total indirect effects (effects of all mediators combined) for MetS on a child's COM and PSE domain were significant, through all child cord blood mediators of LDL, HDL, triglycerides, adiponectin, and leptin for adjusted models.

CONCLUSIONS

The results support the hypothesis that maternal metabolic syndrome classification during pregnancy is associated with some child developmental outcomes at age 5. After adjusting for maternal, child, and environmental covariates, maternal metabolic syndrome classification during pregnancy was associated with children's LIT domain through direct effects of maternal metabolic health and indirect effects of cord blood markers (total effects), and COM and PSE domains via changes only in a child's cord blood markers (total indirect effects).

Molecular hydrogen is a promising therapeutic agent for pulmonary disease

Molecular hydrogen exerts biological effects on nearly all organs. It has anti-oxidative, anti-inflammatory, and anti-aging effects and contributes to the regulation of autophagy and cell death. As the primary organ for gas exchange, the lungs are constantly exposed to various harmful environmental irritants. Short- or long-term exposure to these harmful substances often results in lung injury, causing respiratory and lung diseases. Acute and chronic respiratory diseases have high rates of morbidity and mortality and have become a major public health concern worldwide. For example, coronavirus disease 2019 (COVID-19) caused by severe acute respiratory syndrome coronavirus 2 (SARS-CoV-2) has become a global pandemic. An increasing number of studies have revealed that hydrogen may protect the lungs from diverse diseases, including acute lung injury, chronic obstructive pulmonary disease, asthma, lung cancer, pulmonary arterial hypertension, and pulmonary fibrosis. In this review, we highlight the multiple functions of hydrogen and the mechanisms underlying its protective effects in various lung diseases, with a focus on its roles in disease pathogenesis and clinical significance.

Effects of Calcium Fortified Beverage Intake on Insulin Sensitivity and Antioxidant Metabolism in Healthy Elderly

Calcium, one of the most important nutrients, determines the quality of life of the elderly. It has been reported that 7 out of 10 people over the age of 60 have insufficient calcium intake. The purpose of this study was to evaluate the effect of calcium fortified beverage (CFB) intake on insulin sensitivity and antioxidant metabolism in healthy elderly. A crossover clinical trial was performed and antioxidant status of healthy elderly (age above 65 years, n = 8) was analyzed. Subjects did not take CFB for 0–3 weeks. They then took it for 3–6 weeks. CFB supplementation decreased insulin levels (Δ3–6 weeks: 1.19 ± 0.65 μ IU/mL → Δ0–3 weeks: −0.58 ± 0.38 μ IU/mL). Increasing degree of fasting blood glucose level was suppressed by intake of CFB, although the suppression was not statistically significant. Except for insulin, there were no significant differences in results of biochemical analysis between 0–3 weeks and 3–6 weeks. Catalase activity was significantly increased by CFB supplementation (Δ3–6 weeks: 3.50 ± 5.30 K g/Hb) compared to the no CFB supplementation period (Δ0–3 weeks: −12.48 ± 4.37 K g/Hb). However, the activity of superoxide dismutase and glutathione-peroxidase were not significantly different between 0–3 weeks and 3–6 weeks. H₂O₂-induced DNA oxidative damage was also decreased significantly by CFB supplementation. Taken together, these results indicate that CFB has beneficial effect on insulin sensitivity and some antioxidant enzymes in healthy elderly.

Glucose, lipid and oxidative stress lowering activity of the aqueous extract from leafy stems of Cissus polyantha Gilg & Brandt in dexamethasone-induced hyperglycemia in rats

Background

Diabetes mellitus is a metabolic disorder characterised by chronic hyperglycemia. The present research work aimed to evaluate the hypoglycaemic, hypolipidemic and antioxidant effects of leafy stems of Cissus polyantha Gilg & Brandt in insulin resistant rats.

Methods

The oral glucose tolerance test (OGTT) was performed in normal rats. Hyperglycemia was induced for 8 days by a daily subcutaneous injection of dexamethasone (1 mg/kg) one hour after pretreatment of animals with metformin (40 mg/kg) and C. polyantha extract (111, 222 and 444 mg/kg). Body weight, blood glucose, insulin level, lipid profile, insulin biomarkers, cardiovascular indices and oxidative stress biomarkers were evaluated.

Results

For OGTT, the extract (444 mg/kg) produced a significant drop in blood sugar at the 60th (p < 0.01), 90th (p < 0.01) and 120th min (p < 0.05). Morever, the extract at doses of 222 and 111 mg/kg significantly reduced blood sugar at the 60th (p < 0.01) and 90th min (p < 0.05) respectively. Otherwise, C. polyantha (444 and 222 mg/kg) significantly (p < 0.001) increased body weight and decreased blood sugar on the 4th and 8th days of treatment in insulin resistant rats. The extract also significantly decreased (p < 0.001) serum insulin level, hyperlipidemia, insulin resistance index and cardiovascular indices, and increased gluthathione level, and superoxide dismutase and catalase activity.

Conclusion

The aqueous extract of Cissus polyantha leafy stems (AECPLS) possess hypoglycemic, hypolipidemic and antioxidant activities that could justify its use in traditional medicine for the prevention and treatment of diabetes mellitus and its complications.

Tocomin Restores Endothelium-Dependent Relaxation in the Diabetic Rat Aorta by Increasing NO Bioavailability and Improving the Expression of eNOS

We aimed to determine whether tocomin, an extract from palm oil that has a high tocotrienol content, was able to prevent diabetes-induced endothelial dysfunction. To induce type 1 diabetes streptozotocin (50 mg/kg) was injected into the tail vein of Wistar rats. Six weeks later the diabetic rats, and normal rats injected with citrate buffer, commenced treatment with tocomin (40 mg/kg/day sc) or its vehicle (peanut oil) for a further 4 weeks. Aortae isolated from diabetic rats had impaired acetylcholine (ACh)-induced endothelium-dependent relaxation compared to normal rat aortae but there was no change in endothelium-independent relaxation in response to sodium nitroprusside. By contrast, responses to ACh in aortae from diabetic rats treated with tocomin were not different to normal rats. In addition to impaired endothelium-dependent relaxation the diabetic aortae had increased expression of the NADPH oxidase Nox2 subunit, increased generation of superoxide and decreased expression of eNOS and all of these effects were prevented by tocomin treatment. Tocomin did not affect plasma glucose levels. The impaired response to ACh in vitro was maintained in the presence of TRAM-34 and apamin, selective inhibitors of calcium-activated potassium (K Ca ) channels, indicating diabetes impaired the contribution of NO to endothelium-dependent relaxation. By contrast, neither diabetes nor tocomin treatment influenced EDH-type relaxation as, in the presence of L-NNA, an inhibitor of eNOS, and ODQ, to inhibit soluble guanylate cyclase, responses to ACh were similar in all treatment groups. Thus tocomin treatment improves NO mediated endothelium dependent relaxation in aortae from diabetic rats associated with a decrease in vascular oxidant stress but without affecting hyperglycaemia.

Hypertension in diabetes and the risk of cardiovascular disease

Hypertension (HTN) is an important risk factor for cardiovascular disease and its many manifestations. It shares pathogenic pathways with diabetes and is part of a common metabolic entity, the metabolic syndrome. When combined with diabetes, HTN has been shown to predict and promote increased risk for cardiovascular disease events over and above each risk factor alone. Of the components of this metabolic syndrome, HTN is relatively easy to diagnose and thereby more accessible for implementing preventive and treatment strategies. The recent release of Joint National Committee-8 guidelines for the treatment of HTN has fueled a debate on treatment target goals.

Boosting autophagy in the diabetic heart: a translational perspective

Diabetes, obesity, and dyslipidemia are main risk factors that promote the development of cardiovascular diseases. These metabolic abnormalities are frequently found to be associated together in a highly morbid clinical condition called metabolic syndrome. Metabolic derangements promote endothelial dysfunction, atherosclerotic plaque formation and rupture, cardiac remodeling and dysfunction. This evidence strongly encourages the elucidation of the mechanisms through which obesity, diabetes, and metabolic syndrome induce cellular abnormalities and dysfunction in order to discover new therapeutic targets and strategies for their prevention and treatment. Numerous studies employing both dietary and genetic animal models of obesity and diabetes have demonstrated that autophagy, an intracellular system for protein degradation, is impaired in the heart under these conditions. This suggests that autophagy reactivation may represent a future potential therapeutic intervention to reduce cardiac maladaptive alterations in patients with metabolic derangements. In fact, autophagy is a critical mechanism to preserve cellular homeostasis and survival. In addition, the physiological activation of autophagy protects the heart during stress, such as acute ischemia, starvation, chronic myocardial infarction, pressure overload, and proteotoxic stress. All these aspects will be discussed in our review article together with the potential ways to reactivate autophagy in the context of obesity, metabolic syndrome, and diabetes.

Insulin resistance is associated with DNA damage in peripheral blood cells in non-diabetic patients with genotype 1 chronic hepatitis C

BACKGROUND

In chronic liver diseases of different etiologies, including viral hepatitis, genotoxic effects of oxidative stress have been shown, both in clinical and in experimental conditions, suggesting that this mechanism may contribute to the evolution of the disease.

AIM

To evaluate DNA damage in the peripheral blood of untreated non-diabetic patients with chronic hepatitis C and control subjects, and its correlation with demographic, anthropometric, biochemical, and histological parameters in the patient sample.

PATIENTS AND METHODS

This study comprised 100 subjects of both genders, 60 of whom were treatment-naïve patients with positive serology for genotype 1 hepatitis C. The remaining 40 were blood donors with negative serology for hepatitis who were used as control subjects, and matched by gender, age, weight, and BMI. DNA damage was determined using the comet assay in the total peripheral blood.

RESULTS

The DNA damage evaluated by the comet assay revealed higher values in the group of patients with hepatitis compared with that in the control group. The relationships of the comet assay with the studied variables were assessed using multivariate analysis; significant correlations were only identified with insulin (r = 0.343, p = 0.008) and Homeostasis Model Assessment Insulin Resistance (HOMA-IR) (r = 0.331, p = 0.011).

CONCLUSION

Patients with genotype 1 chronic hepatitis C have higher rates of DNA damage, as determined by comet assay and this alteration is correlated with the HOMA index of insulin resistance.

Obesity-related metabolic syndrome: mechanisms of sympathetic overactivity

The prevalence of the metabolic syndrome has increased worldwide over the past few years. Sympathetic nervous system overactivity is a key mechanism leading to hypertension in patients with the metabolic syndrome. Sympathetic activation can be triggered by reflex mechanisms as arterial baroreceptor impairment, by metabolic factors as insulin resistance, and by dysregulated adipokine production and secretion from visceral fat with a mainly permissive role of leptin and antagonist role of adiponectin. Chronic sympathetic nervous system overactivity contributes to a further decline of insulin sensitivity and creates a vicious circle that may contribute to the development of hypertension and of the metabolic syndrome and favor cardiovascular and kidney disease. Selective renal denervation is an emerging area of interest in the clinical management of obesity-related hypertension. This review focuses on current understanding of some mechanisms through which sympathetic overactivity may be interlaced to the metabolic syndrome, with particular regard to the role of insulin resistance and of some adipokines.

Diabetes and hypertension: is there a common metabolic pathway?

Diabetes and hypertension frequently occur together. There is substantial overlap between diabetes and hypertension in etiology and disease mechanisms. Obesity, inflammation, oxidative stress, and insulin resistance are thought to be the common pathways. Recent advances in the understanding of these pathways have provided new insights and perspectives. Physical activity plays an important protective role in the two diseases. Knowing the common causes and disease mechanisms allows a more effective and proactive approach in their prevention and treatment.

Insulin induces production of new elastin in cultures of human aortic smooth muscle cells

Diabetes mellitus accelerates atherosclerotic progression, peripheral angiopathy development, and arterial hypertension, all of which are associated with elastic fiber disease. However, the potential mechanistic links between insulin deficiency and impaired elastogenesis in diabetes have not been explored. Results of the present study reveal that insulin administered in therapeutically relevant concentrations (0.5 to 10 nmol/L) selectively stimulates formation of new elastic fibers in cultures of human aortic smooth muscle cells. These concentrations of insulin neither up-regulate collagen type I and fibronectin deposition nor stimulate cellular proliferation. Further, the elastogenic effect of insulin occurs after insulin receptor activation, which triggers the PI3K downstream signaling pathway and activates elastin gene transcription. In addition, the promoter region of the human elastin gene contains the CAAATAA sequence, consistent with the FoxO-recognized element, and the genomic effects of insulin occur after removal of the FoxO1 transcriptional inhibitor from the FoxO-recognized element in the elastin gene promoter. In addition, insulin signaling facilitates the association of tropoelastin with its specific 67-kDa elastin-binding protein/spliced form of β-galactosidase chaperone, enhancing secretion. These results are crucial to understanding of the molecular and cellular mechanisms of diabetes-associated vascular disease, and, in particular, endorse use of insulin therapy for treatment of atherosclerotic lesions in patients with type 1 diabetes, in which induction of new elastic fibers would mechanically stabilize the developing plaques and prevent arterial occlusions.

Building multidimensional biomarker views of type 2 diabetes on the basis of protein microheterogeneity

BACKGROUND

In 2008, the US Food and Drug Administration (FDA) issued a Guidance for Industry statement formally recognizing (during drug development) the conjoined nature of type 2 diabetes (T2D) and cardiovascular disease (CVD), which has precipitated an urgent need for panels of markers (and means of analysis) that are able to differentiate subtypes of CVD in the context of T2D. Here, we explore the possibility of creating such panels using the working hypothesis that proteins, in addition to carrying time-cumulative marks of hyperglycemia (e.g., protein glycation in the form of Hb A(₁c)), may carry analogous information with regard to systemic oxidative stress and aberrant enzymatic signaling related to underlying pathobiologies involved in T2D and/or CVD.

METHODS

We used mass spectrometric immunoassay to quantify, in targeted fashion, relative differences in the glycation, oxidation, and truncation of 11 specific proteins.

RESULTS

Protein oxidation and truncation (owing to modified enzymatic activity) are able to distinguish between subsets of diabetic patients with or without a history of myocardial infarction and/or congestive heart failure where markers of glycation alone cannot.

CONCLUSION

Markers based on protein modifications aligned with the known pathobiologies of T2D represent a reservoir of potential cardiovascular markers that are needed to develop the next generation of antidiabetes medications.

Hypertension, dyslipidemia, and insulin resistance in patients with diabetes mellitus or the cardiometabolic syndrome: benefits of vasodilating β-blockers

Hypertension frequently coexists with diabetes and the cardiometabolic syndrome. β-Blockers have been a mainstay for controlling blood pressure for nearly 4 decades. However, β-blockers are perceived to cause glucose and lipid metabolism dysregulation, including hypoglycemia masking, reduced glycemic control, insulin resistance, and dyslipidemia. It should be noted, however, that β-blockers are diverse in their effects on glucose and lipid metabolism. Potential mechanisms that contribute to these metabolic effects include hemodynamic differences, anti-inflammatory and anti-oxidative pathways, and/or weight changes. Traditional β-blockers decrease cardiac output while peripheral vascular resistance increases or remains unchanged, which may result in glucose and lipid abnormalities. In contrast, vasodilating β-blockers reduce peripheral vascular resistance but have little effect on cardiac output. Vasodilating β-blockers may therefore result in less impact on insulin sensitivity and glycemic control, a reduced new-onset diabetes risk, and improved dyslipidemia compared with traditional β-blockers. Because of these effects, vasodilating β-blockers may represent a favorable option in the treatment of high-risk patients with hypertension.

B cells as under-appreciated mediators of non-auto-immune inflammatory disease

B lymphocytes play roles in many auto-immune diseases characterized by unresolved inflammation, and B cell ablation is proving to be a relatively safe, effective treatment for such diseases. B cells function, in part, as important sources of regulatory cytokines in auto-immune disease, but B cell cytokines also play roles in other non-auto-immune inflammatory diseases. B cell ablation may therefore benefit inflammatory disease patients in addition to its demonstrated efficacy in auto-immune disease. Current ablation drugs clear both pro- and anti-inflammatory B cell subsets, which may unexpectedly exacerbate some pathologies. This possibility argues that a more thorough understanding of B cell function in human inflammatory disease is required to safely harness the clinical promise of B cell ablation. Type 2 diabetes (T2D) and periodontal disease (PD) are two inflammatory diseases characterized by little autoimmunity. These diseases are linked by coincident presentation and alterations in toll-like receptor (TLR)-dependent B cell cytokine production, which may identify B cell ablation as a new therapy for co-affected individuals. Further analysis of the role B cells and B cell cytokines play in T2D, PD and other inflammatory diseases is required to justify testing B cell depletion therapies on a broader range of patients.

Endothelial dysfunction: causes and consequences in patients with diabetes mellitus

Vascular endothelium plays a major role in maintaining cardiovascular homeostasis. Nitric oxide is the most powerful vasodilating compound. Diabetes disrupts endothelial integrity through an increased oxidative stress. Recent evidence indicates that there is a strong interaction between diabetes, the secretory proteins of adipocytes, called adipokines, and endothelium. Endothelial dysfunction may precede the development of overt DM, and a prolonged and repeated exposure to postprandial hyperglycemia may play an important role in the development of atherosclerosis, even in those who have normal fasting plasma glucose levels.

An oil mixture with trans-10, cis-12 conjugated linoleic acid increases markers of inflammation and in vivo lipid peroxidation compared with cis-9, trans-11 conjugated linoleic acid in postmenopausal women

A mixture of trans-10, cis-12 (t10,c12) and cis-9, trans-11 (c9,t11) conjugated linoleic acid (CLA mixture) reduced atherosclerosis in animals, thus the effect of these isomers on endothelial dysfunctions leading to inflammation and atherosclerosis is of interest. We gave 75 healthy postmenopausal women a daily supplement of 5.5 g of oil rich in either CLA mixture, an oil rich in the naturally occurring c9,t11 CLA (CLA milk), respectively, or olive oil for 16 wk in a double-blind, randomized, parallel intervention study. We sampled blood and urine before and after the intervention. The ratios of total cholesterol:HDL cholesterol and concentrations of C-reactive protein, fibrinogen, and plasminogen activator inhibitor-1 were significantly higher in women supplemented with the CLA mixture than in those supplemented with CLA milk. Plasma triacylglycerol was significantly higher and HDL cholesterol was lower in women supplemented with the CLA mixture than with olive oil. Both CLA supplements increased lipid peroxidation, a marker of in vivo oxidative stress measured as urinary free 8-iso-prostaglandin F(2alpha). However, the CLA mixture increased lipid peroxidation more than the CLA milk did. The plasma cytokines interleukin-6 and tumor necrosis factor-alpha were not affected by the treatments, nor were any of the other variables measured. In conclusion, oil containing trans-10,cis-12 CLA has several adverse effects on classical and novel markers of coronary vascular disease, whereas the c9,t11 CLA isomer is more neutral, except for a small but significant increase in lipid peroxidation compared with olive oil.

The inhibitory effect of simvastatin on the ADMA-induced inflammatory reaction is mediated by MAPK pathways in endothelial cells

Asymmetric dimethylarginine (ADMA), an endogenous inhibitor of nitric oxide synthase, is emerging as a key contributor for endothelial dysfunction associated with inflammation. Statins can inhibit vascular inflammatory reaction and improve endothelial function. The aim of this study was to investigate in human endothelial cells the signaling pathways of ADMA-induced inflammatory reaction and potential inhibitory effects of simvastatin. Endothelial cells were cultured and used for all of the studies. Tumor necrosis factor-alpha(TNF-alpha) and soluble intercellular adhesion molecule-1 (sICAM-1) were determined by enzyme-linked immunosorbent assay. Nuclear factor-kappaB (NF-kappaB) was assayed by electrophoretic mobility shift assay. The activation of mitogen-activated protein kinases (MAPKs), including p38 MAPK and extracellular signal-related kinase (ERK(1/2)), were characterized by Western blot analysis. Treatment with ADMA (3-30 micromol/L) increased the concentration of sICAM-1 in a dose-dependent manner. ADMA (30 micromol/L) significantly enhanced the concentrations of TNF-alpha and sICAM-1, the activity of NF-kappaB and the phosphorylation of p38 MAPK and ERK(1/2). The increased secretion of TNF-alpha and sICAM-1 and the increased activity of NF-kappaB by ADMA were altered by SB203580 (5 micromol/L) or PD98059 (20 micromol/L), but not by LY294002 (20 micromol/L). Simvastatin (0.1, 0.5, or 2.5 micromol/L) markedly inhibited the elevated concentrations of TNF-alpha and sICAM-1, the activity of NF-kappaB, and the phosphorylation of p38 MAPK and ERK(1/2) induced by ADMA. Simvastatin inhibited ADMA-induced inflammatory reaction by p38 MAPK and ERK(1/2) pathways in cultured endothelial cells.

Apolipoprotein A5 gene promoter region T-1131C polymorphism associates with elevated circulating triglyceride levels and confers susceptibility for development of ischemic stroke

The possible pathogenic role of triglycerides (TG) in the development of ischemic stroke is still under extensive investigation. Recently, apolipoprotein (apo)A5 gene promoter region T-1131C polymorphism has been shown to associate with elevated serum TG levels. In the current work, a total of 302 subjects were classified as being large vessel-associated, small vessel-associated, or belonging to a mixed group of ischemic stroke-affected patients. The level of TG was increased in all groups (p < 0.01). The apoA5-1131C allele frequency was approximately twofold in all groups of stroke patients compared with the controls (5 vs 10-12%; p < 0.05); and the apoA5-1131C allele itself was also found to associate with increased TG levels in all groups. In a multivariate logistic regression analysis model adjusted for differences in age, gender, serum cholesterol, hypertension, presence of diabetes mellitus, smoking and drinking habits, and ischemic heart disease, a significantly increased risk of developing stroke disease was found in patients carrying the apoA5-1131C allele (p < 0.05; odds ratio OR = 2.1 [1.3-4.7]); this association was also proven for all subtypes of the stroke. The results presented here suggest that the apoA5-1131C allele is an independent risk factor for the development of stroke. Being that apoA5 gene is under the control of the peroxisome proliferator-activated receptor alpha, theoretically, the current observations also can have long-term therapeutic consequences.

Differential effects of oral hypoglycemic agents on glucose control and cardiovascular risk

Cardiovascular disease (CVD) burden remains the predominant cause of mortality and morbidity in the United States and in most of the developed world. The ongoing twin epidemics of obesity and type 2 diabetes mellitus provide a groundswell source for sustaining this trend for the foreseeable future (increasing the prevalence of CVD by 2-4 times), unless radical changes are made in public health policy. Oral hypoglycemic agents (OHAs) remain a mainstay for management of type 2 diabetes in most practice settings. Although these agents are primarily prescribed to achieve better glycemic control, it is important to evaluate what effects they have on cardiovascular risk and whether there are significant differences in effects among the different OHAs. This review presents the available data on the effects of the various OHAs on cardiovascular risk surrogates and actual events in retrospective and prospective study design settings.

Inflammation as the key interface of the medical and nutrition universes: a provocative examination of the future of clinical nutrition and medicine

There has been tremendous interest in inflammation by researchers, the medical community, and the lay public. Modulation of injury response is felt to represent a tenuous balance of pro- and anti-inflammatory cytokines. Adverse outcomes may result from severe, sustained, or repeated bouts of inflammation. A critical observation is that nutrition support alone is inadequate to prevent muscle loss during active inflammation. It is necessary to take inflammation into consideration in conducting appropriate nutrition assessment, intervention, and monitoring. A host of medical conditions are actually inflammatory states that have important implications for nutrition care. Multifaceted interventions that may include anti-inflammatory diets, glycemic control, physical activity, appetite stimulants, anabolic agents, anti-inflammatory agents, anticytokines, and probiotics, will be necessary to blunt undesirable aspects of inflammatory response to preserve body cell mass and vital organ functions. Nutrition practitioners can seize this opportunity to be a part of the future medical team that brings highly individualized patient care to the bedside.

Skeletal Muscle Insulin Resistance Is Fundamental to the Cardiometabolic Syndrome

The cardiometabolic syndrome is associated with insulin resistance and a dysregulation of glucose and lipid metabolism that occurs in multiple tissues. Of these, skeletal muscle is the most abundant insulin-sensitive tissue, handling > 40% of the postprandial glucose uptake, while consuming 20% of the body's energy. The inability to efficiently take up and store fuel, and to transition from fat to glucose as the primary source of fuel during times of plenty (increased insulin), has been termed metabolic inflexibility. This resistance to insulin is thought to be a major contributor to the whole-body metabolic dysregulation that leads to increased cardiovascular risk. Recent investigation has identified specific defects in postinsulin receptor signaling in skeletal muscle from resistant humans and animals. Potential mechanisms contributing to this reduced insulin signaling and action include decreases in mitochondrial oxidative capacity, increased intramuscular lipid accumulation, increased reactive oxygen species generation, and up-regulated inflammatory pathways. Future research is focused on understanding these and other potential mechanisms to identify therapeutic targets for reducing cardiometabolic syndrome risk.

The metabolic syndrome: role of skeletal muscle metabolism

Skeletal muscle constitutes the largest insulin-sensitive tissue in the body and is the primary site for insulin-stimulated glucose utilization. Skeletal muscle resistance to insulin is fundamental to the metabolic dysregulation associated with obesity and physical inactivity, and contributes to the development of the metabolic syndrome (MS). The inability to efficiently take up and store fuel, and to transition from fat to glucose as the primary source of fuel during times of caloric abundance (high insulin) or scarcity (low insulin) has been termed metabolic inflexibility which contributes to a whole body metabolic dysregulation and cardiovascular risk. Potential mechanisms contributing to reduced insulin signaling and action in skeletal muscle includes adipose tissue expansion and increased inflammatory adipokines, increased renin-angiotensin-aldosterone system (RAAS) activity, decreases in muscle mitochondrial oxidative capacity, increased intramuscular lipid accumulation, and increased reactive oxygen species. Future research is focused upon understanding these and other potential mechanisms in order to identify therapeutic targets for reducing MS risk. Strategies will include adequate physical activity and maintaining a healthy weight, but may also require specific pharmacologic interventions.