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Alhasaniah AH. l-carnitine: Nutrition, pathology, and health benefits. Saudi J Biol Sci 2023; 30:103555. [PMID: 36632072 PMCID: PMC9827390 DOI: 10.1016/j.sjbs.2022.103555] [Citation(s) in RCA: 10] [Impact Index Per Article: 10.0] [Reference Citation Analysis] [Abstract] [Key Words] [Track Full Text] [Download PDF] [Figures] [Journal Information] [Subscribe] [Scholar Register] [Received: 10/03/2022] [Revised: 12/09/2022] [Accepted: 12/28/2022] [Indexed: 12/31/2022] Open
Abstract
Carnitine is a medically needful nutrient that contributes in the production of energy and the metabolism of fatty acids. Bioavailability is higher in vegetarians than in people who eat meat. Deficits in carnitine transporters occur as a result of genetic mutations or in combination with other illnesses such like hepatic or renal disease. Carnitine deficit can arise in diseases such endocrine maladies, cardiomyopathy, diabetes, malnutrition, aging, sepsis, and cirrhosis due to abnormalities in carnitine regulation. The exogenously provided molecule is obviously useful in people with primary carnitine deficits, which can be life-threatening, and also some secondary deficiencies, including such organic acidurias: by eradicating hypotonia, muscle weakness, motor skills, and wasting are all improved l-carnitine (LC) have reported to improve myocardial functionality and metabolism in ischemic heart disease patients, as well as athletic performance in individuals with angina pectoris. Furthermore, although some intriguing data indicates that LC could be useful in a variety of conditions, including carnitine deficiency caused by long-term total parenteral supplementation or chronic hemodialysis, hyperlipidemias, and the prevention of anthracyclines and valproate-induced toxicity, such findings must be viewed with caution.
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Key Words
- AD, Alzheimer's disease
- AIF, Apoptosis-inducing factor
- Anti-wasting effect
- BBB, Blood–brain barrier
- CC, Cancer cachexia
- CHF, Chronic heart failure
- COPD, Chronic obstructive pulmonary disease
- ESRD, End-stage renal disease
- GOT, Glutamic oxaloacetic transaminase
- HCC, Hepatocellular carcinoma
- HFD, High-Fat Diet
- HOI, Highest observed intake
- Health benefits
- LC, l-carnitine
- MI, myocardial infarction
- MTX, Methotrexate
- NF-kB, Nuclear factor-kB
- Nutrition
- OSL, Observed safe level
- PCD, Primary carnitine deficiency
- Pathology
- ROS, Reactive oxygen species
- SCD, Secondary carnitine deficiency
- TLE, Temporal lobe epilepsy
- VD, Vascular dementia
- l-carnitine
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Affiliation(s)
- Abdulaziz Hassan Alhasaniah
- Department of Clinical Laboratory Sciences, Faculty of Applied Medical Sciences, Najran University, P.O. Box 1988, Najran 61441, Saudi Arabia
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Samsonov MV, Podkuychenko NV, Khapchaev AY, Efremov EE, Yanushevskaya EV, Vlasik TN, Lankin VZ, Stafeev IS, Skulachev MV, Shestakova MV, Vorotnikov AV, Shirinsky VP. AICAR Protects Vascular Endothelial Cells from Oxidative Injury Induced by the Long-Term Palmitate Excess. Int J Mol Sci 2021; 23:ijms23010211. [PMID: 35008640 PMCID: PMC8745318 DOI: 10.3390/ijms23010211] [Citation(s) in RCA: 11] [Impact Index Per Article: 3.7] [Reference Citation Analysis] [Abstract] [Key Words] [MESH Headings] [Track Full Text] [Download PDF] [Figures] [Journal Information] [Subscribe] [Scholar Register] [Received: 11/29/2021] [Revised: 12/20/2021] [Accepted: 12/22/2021] [Indexed: 12/14/2022] Open
Abstract
Hyperlipidemia manifested by high blood levels of free fatty acids (FFA) and lipoprotein triglycerides is critical for the progression of type 2 diabetes (T2D) and its cardiovascular complications via vascular endothelial dysfunction. However, attempts to assess high FFA effects in endothelial culture often result in early cell apoptosis that poorly recapitulates a much slower pace of vascular deterioration in vivo and does not provide for the longer-term studies of endothelial lipotoxicity in vitro. Here, we report that palmitate (PA), a typical FFA, does not impair, by itself, endothelial barrier and insulin signaling in human umbilical vein endothelial cells (HUVEC), but increases NO release, reactive oxygen species (ROS) generation, and protein labeling by malondialdehyde (MDA) hallmarking oxidative stress and increased lipid peroxidation. This PA-induced stress eventually resulted in the loss of cell viability coincident with loss of insulin signaling. Supplementation with 5-aminoimidazole-4-carboxamide-riboside (AICAR) increased endothelial AMP-activated protein kinase (AMPK) activity, supported insulin signaling, and prevented the PA-induced increases in NO, ROS, and MDA, thus allowing to maintain HUVEC viability and barrier, and providing the means to study the long-term effects of high FFA levels in endothelial cultures. An upgraded cell-based model reproduces FFA-induced insulin resistance by demonstrating decreased NO production by vascular endothelium.
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Affiliation(s)
- Mikhail V. Samsonov
- National Medical Research Center for Cardiology, 121552 Moscow, Russia; (M.V.S.); (N.V.P.); (A.Y.K.); (E.E.E.); (E.V.Y.); (T.N.V.); (V.Z.L.); (I.S.S.)
| | - Nikita V. Podkuychenko
- National Medical Research Center for Cardiology, 121552 Moscow, Russia; (M.V.S.); (N.V.P.); (A.Y.K.); (E.E.E.); (E.V.Y.); (T.N.V.); (V.Z.L.); (I.S.S.)
| | - Asker Y. Khapchaev
- National Medical Research Center for Cardiology, 121552 Moscow, Russia; (M.V.S.); (N.V.P.); (A.Y.K.); (E.E.E.); (E.V.Y.); (T.N.V.); (V.Z.L.); (I.S.S.)
| | - Eugene E. Efremov
- National Medical Research Center for Cardiology, 121552 Moscow, Russia; (M.V.S.); (N.V.P.); (A.Y.K.); (E.E.E.); (E.V.Y.); (T.N.V.); (V.Z.L.); (I.S.S.)
| | - Elena V. Yanushevskaya
- National Medical Research Center for Cardiology, 121552 Moscow, Russia; (M.V.S.); (N.V.P.); (A.Y.K.); (E.E.E.); (E.V.Y.); (T.N.V.); (V.Z.L.); (I.S.S.)
| | - Tatiana N. Vlasik
- National Medical Research Center for Cardiology, 121552 Moscow, Russia; (M.V.S.); (N.V.P.); (A.Y.K.); (E.E.E.); (E.V.Y.); (T.N.V.); (V.Z.L.); (I.S.S.)
| | - Vadim Z. Lankin
- National Medical Research Center for Cardiology, 121552 Moscow, Russia; (M.V.S.); (N.V.P.); (A.Y.K.); (E.E.E.); (E.V.Y.); (T.N.V.); (V.Z.L.); (I.S.S.)
| | - Iurii S. Stafeev
- National Medical Research Center for Cardiology, 121552 Moscow, Russia; (M.V.S.); (N.V.P.); (A.Y.K.); (E.E.E.); (E.V.Y.); (T.N.V.); (V.Z.L.); (I.S.S.)
| | - Maxim V. Skulachev
- Belozersky Institute of Physico-Chemical Biology, M. V. Lomonosov Moscow State University, 119234 Moscow, Russia;
| | | | - Alexander V. Vorotnikov
- National Medical Research Center for Cardiology, 121552 Moscow, Russia; (M.V.S.); (N.V.P.); (A.Y.K.); (E.E.E.); (E.V.Y.); (T.N.V.); (V.Z.L.); (I.S.S.)
- Correspondence: (A.V.V.); (V.P.S.)
| | - Vladimir P. Shirinsky
- National Medical Research Center for Cardiology, 121552 Moscow, Russia; (M.V.S.); (N.V.P.); (A.Y.K.); (E.E.E.); (E.V.Y.); (T.N.V.); (V.Z.L.); (I.S.S.)
- Correspondence: (A.V.V.); (V.P.S.)
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Abstract
The endothelium acts as the barrier that prevents circulating lipids such as lipoproteins and fatty acids into the arterial wall; it also regulates normal functioning in the circulatory system by balancing vasodilation and vasoconstriction, modulating the several responses and signals. Plasma lipids can interact with endothelium via different mechanisms and produce different phenotypes. Increased plasma-free fatty acids (FFAs) levels are associated with the pathogenesis of atherosclerosis and cardiovascular diseases (CVD). Because of the multi-dimensional roles of plasma FFAs in mediating endothelial dysfunction, increased FFA level is now considered an essential link in the onset of endothelial dysfunction in CVD. FFA-mediated endothelial dysfunction involves several mechanisms, including dysregulated production of nitric oxide and cytokines, metaflammation, oxidative stress, inflammation, activation of the renin-angiotensin system, and apoptosis. Therefore, modulation of FFA-mediated pathways involved in endothelial dysfunction may prevent the complications associated with CVD risk. This review presents details as to how endothelium is affected by FFAs involving several metabolic pathways.
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Ghosh A, Gao L, Thakur A, Siu PM, Lai CWK. Role of free fatty acids in endothelial dysfunction. J Biomed Sci 2017; 24:50. [PMID: 28750629 PMCID: PMC5530532 DOI: 10.1186/s12929-017-0357-5] [Citation(s) in RCA: 260] [Impact Index Per Article: 37.1] [Reference Citation Analysis] [Abstract] [Key Words] [MESH Headings] [Grants] [Track Full Text] [Download PDF] [Figures] [Journal Information] [Subscribe] [Scholar Register] [Received: 04/05/2017] [Accepted: 07/24/2017] [Indexed: 02/06/2023] Open
Abstract
Plasma free fatty acids levels are increased in subjects with obesity and type 2 diabetes, playing detrimental roles in the pathogenesis of atherosclerosis and cardiovascular diseases. Increasing evidence showing that dysfunction of the vascular endothelium, the inner lining of the blood vessels, is the key player in the pathogenesis of atherosclerosis. In this review, we aimed to summarize the roles and the underlying mechanisms using the evidence collected from clinical and experimental studies about free fatty acid-mediated endothelial dysfunction. Because of the multifaceted roles of plasma free fatty acids in mediating endothelial dysfunction, elevated free fatty acid level is now considered as an important link in the onset of endothelial dysfunction due to metabolic syndromes such as diabetes and obesity. Free fatty acid-mediated endothelial dysfunction involves several mechanisms including impaired insulin signaling and nitric oxide production, oxidative stress, inflammation and the activation of the renin-angiotensin system and apoptosis in the endothelial cells. Therefore, targeting the signaling pathways involved in free fatty acid-induced endothelial dysfunction could serve as a preventive approach to protect against the occurrence of endothelial dysfunction and the subsequent complications such as atherosclerosis.
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Affiliation(s)
- Arijit Ghosh
- Department of Health Technology and Informatics, The Hong Kong Polytechnic University, HKSAR, China
- Department of Biomedical Sciences, City University of Hong Kong, HKSAR, China
| | - Lei Gao
- Department of Health Technology and Informatics, The Hong Kong Polytechnic University, HKSAR, China
| | - Abhimanyu Thakur
- Department of Biomedical Sciences, City University of Hong Kong, HKSAR, China
| | - Parco M. Siu
- Department of Health Technology and Informatics, The Hong Kong Polytechnic University, HKSAR, China
| | - Christopher W. K. Lai
- Department of Health Technology and Informatics, The Hong Kong Polytechnic University, HKSAR, China
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Preventive effect of l-carnitine and its derivatives on endothelial dysfunction and platelet aggregation. Clin Nutr ESPEN 2016; 15:1-10. [DOI: 10.1016/j.clnesp.2016.06.009] [Citation(s) in RCA: 11] [Impact Index Per Article: 1.4] [Reference Citation Analysis] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 05/16/2016] [Accepted: 06/10/2016] [Indexed: 11/18/2022]
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Fukami K, Yamagishi SI, Sakai K, Kaida Y, Minami A, Nakayama Y, Ando R, Obara N, Ueda S, Wada Y, Okuda S. Carnitine deficiency is associated with late-onset hypogonadism and depression in uremic men with hemodialysis. Aging Male 2014; 17:238-42. [PMID: 24611884 DOI: 10.3109/13685538.2014.888053] [Citation(s) in RCA: 10] [Impact Index Per Article: 1.0] [Reference Citation Analysis] [Abstract] [Key Words] [MESH Headings] [Track Full Text] [Journal Information] [Submit a Manuscript] [Subscribe] [Scholar Register] [Indexed: 01/31/2023] Open
Abstract
Late-onset hypogonadism (LOH) and depression contribute to cardiovascular disease (CVD) in male hemodialysis (HD) patients. Carnitine deficiency is frequently observed in HD patients, playing a role in CVD. We examined whether carnitine deficiency was independently associated with LOH and depression in these patients. Twenty-six male HD patients underwent determinations of serum levels of free carnitine and testosterone. Status of LOH and depression were evaluated by questionnaires using aging male symptoms' (AMS) scale and self-rating depression scale (SDS), respectively. Free carnitine and testosterone levels in male HD patients were significantly lower than those in age-matched healthy male subjects. Linear regression analysis showed that AMS scale was positively associated with SDS. Univariate regression analysis revealed that total carnitine (inversely), free carnitine (inversely) and HD duration were correlated with AMS scale. Multiple stepwise regression analysis revealed that free carnitine was an independent determinant of AMS scale. Furthermore, free carnitine was also independently correlated with SDS in male HD patients. This study demonstrated that decreased free carnitine levels were independently associated with AMS scale and SDS in male HD patients. The observations suggest that decreased free carnitine levels could be a marker and therapeutic target of LOH and depression in uremic men with HD.
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Affiliation(s)
- Kei Fukami
- Division of Nephrology, Department of Medicine
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McCarty MF. L-carnitine consumption, its metabolism by intestinal microbiota, and cardiovascular health. Mayo Clin Proc 2013; 88:786-9. [PMID: 23910406 DOI: 10.1016/j.mayocp.2013.06.004] [Citation(s) in RCA: 13] [Impact Index Per Article: 1.2] [Reference Citation Analysis] [MESH Headings] [Track Full Text] [Journal Information] [Submit a Manuscript] [Subscribe] [Scholar Register] [Received: 04/17/2013] [Accepted: 06/07/2013] [Indexed: 01/06/2023]
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Abstract
In contrast to their role in cell types with higher energy demands, mitochondria in endothelial cells primarily function in signaling cellular responses to environmental cues. This article provides an overview of key aspects of mitochondrial biology in endothelial cells, including subcellular location, biogenesis, dynamics, autophagy, reactive oxygen species production and signaling, calcium homeostasis, regulated cell death, and heme biosynthesis. In each section, we introduce key concepts and then review studies showing the importance of that mechanism to endothelial control of vasomotor tone, angiogenesis, and/or inflammatory activation. We particularly highlight the small number of clinical and translational studies that have investigated each mechanism in human subjects. Finally, we review interventions that target different aspects of mitochondrial function and their effects on endothelial function. The ultimate goal of such research is the identification of new approaches for therapy. The reviewed studies make it clear that mitochondria are important in endothelial physiology and pathophysiology. A great deal of work will be needed, however, before mitochondria-directed therapies are available for the prevention and treatment of cardiovascular disease.
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Affiliation(s)
- Matthew A Kluge
- Evans Department of Medicine, Whitaker Cardiovascular Institute, Boston University School of Medicine, Boston, MA 02118, USA
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Evidence for a Positive Association Between Serum Carnitine and Free Testosterone Levels in Uremic Men with Hemodialysis. Rejuvenation Res 2013; 16:200-5. [DOI: 10.1089/rej.2012.1399] [Citation(s) in RCA: 3] [Impact Index Per Article: 0.3] [Reference Citation Analysis] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 11/12/2022] Open
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Vilskersts R, Kuka J, Svalbe B, Cirule H, Liepinsh E, Grinberga S, Kalvinsh I, Dambrova M. Administration of L-carnitine and mildronate improves endothelial function and decreases mortality in hypertensive Dahl rats. Pharmacol Rep 2011; 63:752-62. [DOI: 10.1016/s1734-1140(11)70587-4] [Citation(s) in RCA: 17] [Impact Index Per Article: 1.3] [Reference Citation Analysis] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 01/07/2010] [Revised: 11/29/2010] [Indexed: 11/28/2022]
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Cave MC, Hurt RT, Frazier TH, Matheson PJ, Garrison RN, McClain CJ, McClave SA. Obesity, inflammation, and the potential application of pharmaconutrition. Nutr Clin Pract 2008; 23:16-34. [PMID: 18203961 DOI: 10.1177/011542650802300116] [Citation(s) in RCA: 108] [Impact Index Per Article: 6.8] [Reference Citation Analysis] [Abstract] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 12/15/2022] Open
Abstract
Obesity is an emerging problem worldwide. Hospitalized obese patients often have a worse outcome than patients of normal weight, particularly in the setting of trauma and critical care. Obesity creates a low-grade systemic inflammatory response syndrome (SIRS) that is similar (but on a much smaller scale) to gram-negative sepsis. This process involves up-regulation of systemic immunity, is characterized clinically by insulin resistance and the metabolic syndrome, and puts the patient at increased risk for organ failure, infectious morbidity, and mortality. Through lipotoxicity and cytokine dysregulation, obesity may act to prime the immune system, predisposing to an exaggerated subsequent immune response when a second clinical insult occurs (such as trauma, burns, or myocardial infarction). Specialized nutrition therapy for such patients currently consists of a hypocaloric, high-protein diet. However, this approach does not address the putative pathophysiologic mechanisms of inflammation and altered metabolism associated with obesity. A number of dietary agents such as arginine, fish oil, and carnitine may correct these problems at the molecular level. Pharmaconutrition formulas may provide exciting innovations for the nutrition therapy of the obese patient.
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Affiliation(s)
- Matt C Cave
- Department of Medicine, University of Louisville School of Medicine, 500 S. Jackson Street, University of Louisville, Louisville, KY 40292, USA
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Poorabbas A, Fallah F, Bagdadchi J, Mahdavi R, Aliasgarzadeh A, Asadi Y, Koushavar H, Vahed Jabbari M. Determination of free L-carnitine levels in type II diabetic women with and without complications. Eur J Clin Nutr 2007; 61:892-5. [PMID: 17311064 DOI: 10.1038/sj.ejcn.1602594] [Citation(s) in RCA: 34] [Impact Index Per Article: 2.0] [Reference Citation Analysis] [Abstract] [MESH Headings] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 11/09/2022]
Abstract
BACKGROUND Studies on the determination of carnitine levels and nutritional status in patients of type II diabetes. OBJECTIVE We designed this study to determine changes of serum-free L-carnitine in type II diabetic women. DESIGN A cross-sectional study (case-control study). SETTING Clinical of Endocrinology and Metabolism, Sina Hospital, Pharmacological Research Center, Tabriz Medical university, Iran. PATIENTS AND METHODS Taking into account the importance of the control of diabetes, in the present case-control study, the levels of serum-free L-carnitine, blood glucose and lipids, systolic and diastolic blood pressure, body mass index (BMI) and nutritional status assessed in the case and control groups which were selected by the simple sampling method. The control group (n=18) included patients with no complications and the case group (n=33) was grouped into three subgroups including patients with retinopathy, hyperlipidemia and neuropathy. RESULTS Study results indicated that the mean serum-free L-carnitine concentration in the case group was significantly lower than its mean concentration level in the control group, 39.63+/-8.99 vs 53.42+/-0.93 micromol/l, respectively (P<0.001). Serum-free L-carnitine in retinopathy, hyperlipidemia and neuropathy case subgroups were 39.03+/-9.89, 39.63+/-8.99 and 40.44+/-12.50 micromol/l, respectively (P>0.05). No significant difference was found between the serum-free carnitine levels of the case subgroups. The mean blood glucose, triglycerides, total cholesterol, low-density lipoprotein cholesterol, very low-density lipoprotein cholesterol levels and systolic and diastolic blood pressure were significantly higher in the case group than in the control group. CONCLUSION In this study, the mean serum-free L-carnitine levels in diabetic patients with complications was almost 25% lower than in diabetic patients with no complications. On the basis of the study results, carnitine supplementation in diabetic patients, especially in patients with diabetes complications, might be useful.
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Bradley R, Oberg EB, Calabrese C, Standish LJ. Algorithm for Complementary and Alternative Medicine Practice and Research in Type 2 Diabetes. J Altern Complement Med 2007; 13:159-75. [PMID: 17309390 DOI: 10.1089/acm.2006.6207] [Citation(s) in RCA: 21] [Impact Index Per Article: 1.2] [Reference Citation Analysis] [Abstract] [MESH Headings] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 12/14/2022] Open
Abstract
OBJECTIVE To develop a model to direct the prescription of nutritional and botanical medicines in the treatment of type 2 diabetes for both clinical and research purposes. METHODS Available literature on nutritional and botanical medicines was reviewed and categorized as follows: antioxidant/anti-inflammatory; insulin sensitizer; and beta-cell protectant/insulin secretagogue. Literature describing laboratory assessment for glycemic control, insulin resistance, and beta-cell reserve was also reviewed and a clinical decision tree was developed. RESULTS Clinical algorithms were created to guide the use of nutritional and botanic medicines using validated laboratory measures of glycemic control, insulin sensitivity, and beta-cell reserve. Nutrient and botanic medicines with clinical trial research support include coenzyme Q10, carnitine, alpha-lipoic acid, N-acetylcysteine, vitamin D, vitamin C, vitamin E, chromium, vanadium, omega-3 fatty acids, cinnamon (Cinnamomum cassia), fenugreek (Trigonella foenum-graecum), and gymnema (Gymnema sylvestre). CONCLUSIONS Clinical algorithms can direct supplementation in clinical practice and provide research models for clinical investigation. Algorithms also provide a framework for integration of future evidence as it becomes available. Research funding to investigate potentially beneficial practices in complementary medicine is critically important for optimal patient care and safety.
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El-Beshlawy A, Abd El Raouf E, Mostafa F, Talaat M, Isma'eel H, Aoun E, Hoffbrand AV, Taher A. Diastolic dysfunction and pulmonary hypertension in sickle cell anemia: is there a role for L-carnitine treatment? Acta Haematol 2006; 115:91-6. [PMID: 16424656 DOI: 10.1159/000089472] [Citation(s) in RCA: 11] [Impact Index Per Article: 0.6] [Reference Citation Analysis] [Abstract] [MESH Headings] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 11/19/2022]
Abstract
Clinical manifestations of cardiovascular abnormalities in patients with sickle cell (SC) anemia are well documented. Many variables were assessed in our study before and after administration of L-carnitine to randomly selected 37 SC disease (SCD) children for a period of 6 months. Variables such as weight, height, serum ferritin levels, units of blood transfused and the number of veno-occlusive crises all showed significant improvement after the 6 months of therapy with L-carnitine. Our study also showed that cardiac diastolic function and pulmonary hypertension are common in pediatric SCD patients. These two disorders showed some improvement after L-carnitine administration. Therefore, L-carnitine deserves a rigorous large-scale randomized clinical trial to evaluate its potential benefits as treatment for SCD patients with cardiac complications.
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Affiliation(s)
- A El-Beshlawy
- Department of Pediatrics, Faculty of Medicine, Cairo University, Cairo, Egypt.
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Schreiber BD. Debate Forum: Levocarnitine Therapy Is Rational and Justified in Selected Dialysis Patients. Blood Purif 2005; 24:128-39. [PMID: 16361853 DOI: 10.1159/000089449] [Citation(s) in RCA: 15] [Impact Index Per Article: 0.8] [Reference Citation Analysis] [Abstract] [MESH Headings] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 11/19/2022]
Abstract
Carnitine is a metabolic cofactor which is essential for normal fatty acid metabolism. Patients with chronic kidney disease on dialysis have been shown both to suffer from disordered fatty acid metabolism and to have a significant deficiency in plasma and tissue carnitine. Aberrant fatty acid metabolism has been associated with a number of cellular abnormalities such as increased mitochondrial permeability (a promoter of apoptosis), insulin resistance, and enhanced generation of free radicals. These cellular abnormalities have, in turn, been correlated with pathological clinical conditions common in dialysis patients including cardiomyopathy with attendant hypotension and resistance to the therapeutic effect of recombinant human erythropoietin (EPO). In 1999, the Food and Drug Administration approved levocarnitine injection for the prevention and treatment of carnitine deficiency in patients on dialysis based on documentation of free plasma carnitine levels in dialysis patients similar to other serious carnitine deficiency states for which treatment was required. Data analysis performed by expert panels convened by both the American Association of Kidney Patients and, subsequently, the National Kidney Foundation recommended a trial of levocarnitine therapy for specific subsets of dialysis patients including those with EPO resistance, dialysis-related hypotension, cardiomyopathy and muscle weakness. In 2003, the Centers for Medicare and Medicaid services convened a Medical Advisory Committee which established reimbursement on a national level for carnitine-deficient dialysis patients who had either dialysis-related hypotension or EPO resistance. Recently, a correlation between reductions in hospitalization rates of dialysis patients receiving levocarnitine therapy has been demonstrated in a large retrospective study. Despite data-based recommendations and national reimbursement, only a small minority of dialysis patients have been prescribed a therapeutic trial of levocarnitine. Whereas the reasons for the reluctance of nephrologists to prescribe this therapeutic trial are unclear, possible explanations include a lack of appreciation of the pivotal role played by carnitine in cellular metabolism and the strength of evidence for a substantial deficiency of carnitine in dialysis patients, an underestimation of the prognostic import of EPO resistance and dialysis-related hypotension, inadequate dissemination of the clinical trial data supporting the use of levocarnitine in dialysis patients, and the heterogeneous clinical response of dialysis patients to levocarnitine therapy. Difficulties in documenting both initial eligibility and evidence of improvement as a result of therapy may also be a contributing factor. This paper discusses the biological role of carnitine and its particular relevance to dialysis patients. Clinical trial data concerning an effect of therapy on EPO resistance and dialysis-related hypotension are summarized along with a discussion of the logic behind the use of levocarnitine in dialysis. Finally, the difficulties posed by a reimbursement policy based on clinical as opposed to laboratory endpoints and a heterogeneous response to therapy are addressed.
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Affiliation(s)
- Brian D Schreiber
- Division of Nephrology, Department of Medicine, Medical College of Wisconsin, Milwaukee, WI 54956, USA.
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