Effects of propionyl-carnitine in patients with type 2 diabetes and peripheral vascular disease: results of a pilot trial

Study on the mechanism of American ginseng extract for treating type 2 diabetes mellitus based on metabolomics

American ginseng extract (AGE) is an efficient and low-toxic adjuvant for type 2 diabetes mellitus (T2DM). However, the metabolic mechanisms of AGE against T2DM remain unknown. In this study, a rat model of T2DM was created and administered for 28 days. Their biological (body weight and serum biochemical indicators) and pathological (pancreatic sections stained with HE) information were collected for further pharmacodynamic evaluation. Moreover, an ultra-performance liquid chromatography–mass spectrometry–based (UHPLC–MS/MS–based) untargeted metabolomics method was used to identify potential biomarkers of serum samples from all rats and related metabolic pathways. The results indicated that body weight, fasting blood glucose (FBG), fasting blood insulin (FINS), blood triglyceride concentration (TG), high-density lipoprotein cholesterol (HDL-C), insulin resistance index (HOMA-IR) and insulin sensitivity index (ISI), and impaired islet cells were significantly improved after the high dose of AGE (H_AGE) and metformin treatment. Metabolomics analysis identified 101 potential biomarkers among which 94 metabolites had an obvious callback. These potential biomarkers were mainly enriched in nine metabolic pathways linked to amino acid metabolism and lipid metabolism. Tryptophan metabolism and glutathione metabolism, as differential metabolic pathways between AGE and metformin for treating T2DM, were further explored. Further analysis of the aforementioned results suggested that the anti-T2DM effect of AGE was closely associated with inflammation, oxidative stress, endothelial dysfunction, dyslipidemia, immune response, insulin resistance, insulin secretion, and T2DM-related complications. This study can provide powerful support for the systematic exploration of the mechanism of AGE against T2DM and a basis for the clinical diagnosis of T2DM.

The impact of nutrition on the development and progression of peripheral artery disease: A systematic review

BACKGROUND & AIMS

This systematic review sought to identify and summarize existing evidence for the impact of nutrition on the development, progression, and outcomes of peripheral artery disease (PAD).

METHODS

We performed a systematic literature search of available studies published between January 1974 and December 2019. Randomized controlled trials (RCT), observational studies, and cross-sectional studies reporting either the primary or secondary prevention of PAD with nutritional intake were included. The quality assessment was performed for the RCTs, without pooling a meta-risk estimate.

RESULTS

Among a total of 8502 records screened, 186 full texts were assessed for eligibility, and 82 studies (30% RCT) were analyzed. The nutrients were structured in fruits, vegetables and antioxidants, fats and oils, dietary fiber, meat, proteins, vitamins and trace elements, and diets and lifestyle. The findings of the current systematic review indicate that the Mediterranean diet, nuts, and polyunsaturated fat are associated with a lower incidence of PAD and saturated fat, cholesterol, and processed meat were associated with higher rates of cardiovascular events in patients suffering from PAD.

CONCLUSIONS

The current review found evidence of a beneficial impact of the Mediterranean diet including nuts in this target population. More RCTs and high-quality registries are needed that focus on nutritional habits among patients with PAD to design appropriate preventive programs.

Mitoprotective Clinical Strategies in Type 2 Diabetes and Fanconi Anemia Patients: Suggestions for Clinical Management of Mitochondrial Dysfunction

Oxidative stress (OS) and mitochondrial dysfunction (MDF) occur in a number of disorders, and several clinical studies have attempted to counteract OS and MDF by providing adjuvant treatments against disease progression. The present review is aimed at focusing on two apparently distant diseases, namely type 2 diabetes (T2D) and a rare genetic disease, Fanconi anemia (FA). The pathogenetic links between T2D and FA include the high T2D prevalence among FA patients and the recognized evidence for OS and MDF in both disorders. This latter phenotypic/pathogenetic feature-namely MDF-may be regarded as a mechanistic ground both accounting for the clinical outcomes in both diseases, and as a premise to clinical studies aimed at counteracting MDF. In the case for T2D, the working hypothesis is raised of evaluating any in vivo decrease of mitochondrial cofactors, or mitochondrial nutrients (MNs) such as α-lipoic acid, coenzyme Q10, and l-carnitine, with possibly combined MN-based treatments. As for FA, the established knowledge of MDF, as yet only obtained from in vitro or molecular studies, prompts the requirement to ascertain in vivo MDF, and to design clinical studies aimed at utilizing MNs toward mitigating or delaying FA's clinical progression. Altogether, this paper may contribute to building hypotheses for clinical studies in a number of OS/MDF-related diseases.

Branched Chain Amino Acids, Androgen Hormones, and Metabolic Risk Across Early Adolescence: A Prospective Study in Project Viva

OBJECTIVE

This study aimed to examine the associations of two obesity-related metabolite patterns with changes in metabolic biomarkers during early adolescence.

METHODS

Multivariable linear regression was used to examine associations of branched chain amino acid (BCAA) and androgen hormone patterns with changes in glycemia (fasting glucose, insulin, homeostatic model assessment of insulin resistance), adipokines (leptin, adiponectin), inflammation (C-reactive protein, interleukin-6), lipid profile, and blood pressure during ∼5 years of follow-up among 213 children aged 6 to 10 years at baseline. Covariates included baseline age, pubertal status, biomarker level, and BMI percentile, and age at follow-up. Interactions with sex and baseline BMI percentile were also considered.

RESULTS

The median age at baseline was 7.7 years; 48.8% were boys. In adjusted models, each 1 unit of the BCAA pattern corresponded with a 4.82 (95% CI: 0.92 to 8.71) mg/dL decrease in fasting glucose in boys. In girls, the BCAA pattern was associated with an increase in triglycerides (4.17 [0.03 to 8.32] mg/dL). The androgen pattern was associated with decreased leptin (-2.35 [-4.34 to -0.35] ng/dL) and increased C-reactive protein (0.28 [0.03 to 0.54] mg/dL) in girls. These relationships did not differ by baseline BMI percentile.

CONCLUSIONS

The BCAA and androgen hormone metabolite patterns are related to changes in metabolic parameters in a sex-specific manner during early adolescence.

Role of carnitine and its derivatives in the development and management of type 2 diabetes

Type 2 diabetes is a highly prevalent chronic metabolic disorder characterized by hyperglycemia and associated with several complications such as retinopathy, hyperlipidemia and polyneuropathy. The dysregulated fatty acid metabolism along with tissue lipid accumulation is generally assumed to be associated in the development of insulin resistance and T2D. Moreover, several studies suggest a central role for oxidative stress in the pathogenesis of the disease. Since L-carnitine (LC) has an indispensable role in lipid metabolism via its involvement in the β-oxidation of long-chain fatty acids and it has antioxidant properties as well, carnitine supplementation may prove to be an effective tool in the management of the clinical course of T2D. In this review we summarize the results from animal and clinical studies demonstrating the effects of supplementation with LC or LC derivatives (acetyl-LC, propionyl-LC) on various metabolic and clinical parameters associated with T2D.

Current experience in testing mitochondrial nutrients in disorders featuring oxidative stress and mitochondrial dysfunction: rational design of chemoprevention trials

An extensive number of pathologies are associated with mitochondrial dysfunction (MDF) and oxidative stress (OS). Thus, mitochondrial cofactors termed "mitochondrial nutrients" (MN), such as α-lipoic acid (ALA), Coenzyme Q10 (CoQ10), and l-carnitine (CARN) (or its derivatives) have been tested in a number of clinical trials, and this review is focused on the use of MN-based clinical trials. The papers reporting on MN-based clinical trials were retrieved in MedLine up to July 2014, and evaluated for the following endpoints: (a) treated diseases; (b) dosages, number of enrolled patients and duration of treatment; (c) trial success for each MN or MN combinations as reported by authors. The reports satisfying the above endpoints included total numbers of trials and frequencies of randomized, controlled studies, i.e., 81 trials testing ALA, 107 reports testing CoQ10, and 74 reports testing CARN, while only 7 reports were retrieved testing double MN associations, while no report was found testing a triple MN combination. A total of 28 reports tested MN associations with "classical" antioxidants, such as antioxidant nutrients or drugs. Combinations of MN showed better outcomes than individual MN, suggesting forthcoming clinical studies. The criteria in study design and monitoring MN-based clinical trials are discussed.

Carnitine derivatives: clinical usefulness

PURPOSE OF REVIEW

Carnitine and its derivatives are natural substances involved in both carbohydrate and lipid metabolism. This review summarizes the recent progress in the field in relation to the molecular mechanisms.

RECENT FINDINGS

The pool of different carnitine derivatives is formed by acetyl-L-carnitine (ALC), propionyl-L-carnitine (PLC), and isovaleryl-carnitine. ALC may have a preferential effect on the brain tissue. ALC represents a compound of great interest for its wide clinical application in various neurological disorders: it may be of benefit in treating Alzheimer's dementia, depression in the elderly, HIV infection, chronic fatigue syndrome, peripheral neuropathies, ischemia and reperfusion of the brain, and cognitive impairment associated with various conditions. PLC has been demonstrated to replenish the intermediates of the tricarboxylic acid cycle by the propionyl-CoA moiety, a greater affinity for the sarcolemmal carrier, peripheral vasodilator activity, a greater positive inotropism, and more rapid entry into myocytes. Most studies of the therapeutic use of PLC are focused on the prevention and treatment of ischemic heart disease, congestive heart failure, hypertrophic heart disease, and peripheral arterial disease. ALC and PLC are considered well tolerated without significant side-effects.

SUMMARY

A number of therapeutic effects possibly come from the interaction of carnitine and its derivatives with the elements of cellular membranes.

Critical update for the clinical use of L-carnitine analogs in cardiometabolic disorders

Acetyl-L-carnitine (ALC) and propionyl-L-carnitine (PLC) are two naturally occurring carnitine derivates formed by carnitine acetyltransferase. The beneficial cardiovascular effects of ALC and PLC have been extensively evaluated in animals and humans during the last 20 years. For instance, many clinical trials have suggested ALC and PLC as potential strategies in the management of peripheral arterial disease, heart and cerebral ischemia, and congestive heart failure. As a result, several experts have already aimed to revise the clinical evidence supporting the therapeutic use of ALC and PLC. On the basis of their conclusions, our aim was a critical review of the effectiveness of ALC and PLC in the treatment of cardiovascular diseases. Type 2 diabetes mellitus is an independent risk factor for the development of cardiovascular disease. Therefore we also describe recent studies that have addressed the emerging use of ALC and PLC amelioration of the insulin resistant state and its related morbidities.

Inspiratory muscle strength is correlated with carnitine levels in type 2 diabetes

INTRODUCTION

Plasma carnitine insufficiency has been known to cause muscle weakness. Carnitine levels and pulmonary functions were lower in patients with diabetes.

PATIENTS AND METHODS

To determine whether pulmonary functions are correlated with carnitine levels in patients with type 2 diabetes. In this study, we evaluated pulmonary functions and carnitine concentrations in 49 patients with type 2 diabetes and 34 healthy controls.

RESULTS

Carnitine levels were lower in type 2 diabetes group than control group (52.56 +/- 12.38 and 78.96 +/- 10.66 hmol/mL, respectively, p < 0.0001). Pulmonary functions were not significantly different between groups. Carnitine levels were not correlated with age, duration of diabetes, fasting blood glucose levels, and glycemic control (HbA1c%) in patients with type 2 diabetes. However, carnitine levels in patient group were correlated with % forced vital capacity (FVC%) (r = 0.35, p = 0.016), % forced expiratory volume in 1 s (FEV1%) (r = 0.318, p= 0.029), FEV1/FVC (r= 0.302, p= 0.039), inspiratory muscle strength (PImax) (r = 0.407, p = 0.023), and PImax% (r = 0.423, p= 0.018).

CONCLUSION

This study suggests that low carnitine levels may be associated with lower PImax and PImax% in type 2 diabetes.

Propionyl l-carnitine: intermittent claudication and peripheral arterial disease

Peripheral arterial disease (PAD) is a clinical manifestation of underlying aorto-iliac and leg atherosclerosis that is characterized by different stages of stenosis and obstruction. It affects approximately 12% of the adult population and about 20% of people over the age of 70 years, and is associated with increased cardiovascular (CV) and cerebrovascular morbidity. Intermittent claudication (IC) is the major symptom of PAD; it is defined as cramping leg pain (in the buttock, thigh, or calf) while/after clim bing one or two flights of stairs, or during walking. The goals of IC management are to: slow the progression of local and systemic atherosclerosis, prevent major fatal and nonfatal CV events (myocardial infarction and stroke), improve walking capacity, prevent and reduce resting pain and cutaneous lesions. Propionyl L-carnitine is an acyl derivative of levocarnitine (L-carnitine) and is indicated for patients with peripheral arterial occlusive disease. It corrects secondary muscle carnitine deficiency in patients with PAD, significantly improving the walking capacity; it is a free radical that produces positive effects on endothelial function; it protects from oxidative stress; and it enhances most measures of quality of life. The recent Trans-Atlantic Inter-Society Consensus II update recommends the use of propionyl L-carnitine in combination with physical training to improve the symptoms associated with PAD.

L-carnitine: implications in the treatment of the metabolic syndrome and Type 2 diabetes

The metabolic syndrome (MS) is a conglomeration of inter-related common clinical disorders, including obesity, glucose intolerance, hypertension and dyslipidemia, which predispose to Type 2 diabetes (T2D) and cardiovascular diseases. Hyperinsulinemia, per se, and insulin resistance are the pathogenic factors associated with the metabolic risk factors. Since these risk factors are the most frequent causes for mortality among patients with T2D and the MS, treatments targeting normalization of both lipid and glucose homeostasis are of interest. The crucial role of L-carnitine (CA) as a regulator of lipid and glucose metabolism has raised considerable interest in its use as a potential tool for therapeutic intervention in the MS. Several clinical studies have, therefore, been undertaken to examine the efficacy and other benefits in the treatment of T2D and the MS. Studies from rodent models of MS have also shown the positive effects of CA on several components of the syndrome. CA, being an endogenous water-soluble nutrient, could be a safe adjunct and a relevant future drug for the MS. This review provides an overview on the importance of CA in T2D and the MS and the need for further evaluation of its inclusion in treatment protocols.

Propionyl-L-carnitine improves hemodynamics and metabolic markers of cardiac perfusion during coronary surgery in diabetic patients

Diabetic hearts are particularly vulnerable to ischemia-reperfusion injury during cardiac surgery. Application of carnitine derivatives could be beneficial not only because of metabolic effects but also by protecting vasculature. This study aimed to evaluate hemodynamic changes associated with propionyl-L-carnitine and L-carnitine administration and its correlation with biochemical markers of cardiac vascular function.

METHODS

Sixty-eight diabetic patients undergoing cardiopulmonary bypass coronary operation were given intravenously 20 mg/kg b.w. L-carnitine (LC), 24 mg/kg b.w. propionyl-L-carnitine (PC), or placebo (Cont). Endothelin and nucleotide metabolites were determined intraoperatively in arterial and coronary sinus blood and heart biopsies.

RESULTS

Cardiac index at 6 and 12 h after cardiopulmonary bypass was significantly higher in PC (3.30 +/- 0.12 and 3.47 +/- 0.15 L/min/m2) as compared to Cont (2.92 +/- 0.13 and 2.91 +/- 0.16 L/min/m2; P = 0.04 and P = 0.01, respectively). Mean pulmonary artery pressure was lower in PC at 6 (20.8 +/- 0.91 mmHg) and 12 h (20.7 +/- 0.81 mmHg) in comparison to Cont (23.5 +/- 0.75 and 23.4 +/- 0.75 mmHg; P = 0.03 and P = 0.02, respectively). Trans-cardiac endothelin difference on reperfusion was higher in Cont (0.33 +/- 0.26 pmol/L) than in LC (-0.61 +/- 0.24 pmol/L, P = 0.012) and tended to be higher than in PC (-0.29 +/- 0.17 pmol/L, P = 0.056). Trans-cardiac hypoxanthine difference after 10 min reperfusion was significantly higher in Cont (6.22 +/- 1.08 micromol/L) in comparison to LC (3.17 +/- 0.66 micromol/L, P = 0.025) and PC (2.36 +/- 0.73 micromol/L, P = 0.006). Myocardial hypoxanthine concentration was lowest in PC.

CONCLUSIONS

Significant improvement of hemodynamics following propionyl-L-carnitine administration in diabetic patients undergoing on-bypass coronary surgery was accompanied by reduced trans-cardiac endothelin difference and rapid hypoxanthine washout during reperfusion suggesting improvement of metabolism or vascular function.