PMCC PMCC

Search tips
Search criteria

Advanced
Results 1-4 (4)
 

Clipboard (0)
None
Journals
Authors
Year of Publication
Document Types
1.  "The metabolic syndrome... is dead": These reports are an exaggeration 
The debates continue over the validity of the metabolic syndrome concept. The continuous increment of the obesity pandemic is almost worldwide paralleled by rising rates of metabolic syndrome prevalence. Then, it seems obvious that these debates drove the need for further investigations as well as a deeper cooperation between relevant national and international organizations regarding the issue. Instead, part of the scientific community elected to totally "dismiss" the concept of the metabolic syndrome. Meanwhile, the best available evidence from three consecutive large meta-analyses has systematically shown that people with metabolic syndrome are at increased risk of cardiovascular events. The most recent and largest of them included near one million patients (total n = 951,083). The investigators concluded that the metabolic syndrome is associated with a 2-fold increase in cardiovascular outcomes and a 1.5-fold increase in all-cause mortality rates. One of the ways to hit the metabolic syndrome is an utterly simplistic view on this concept as a predictive tool only. Of course, the presence of the metabolic syndrome possesses a definite predictive value, but first of all it is a widely accepted concept regarding a biological condition based on the complex and interrelated pathophysiological mechanisms starting from excess central adiposity and insulin resistance. Therefore, it is completely unfair to compare it with statistically constructed predictive tools, including stronger prognostic variables even unrelated to each other from the biological point of view. For example, in the criteria for metabolic syndrome (in contrast to Framingham score) age and cholesterol - presumably low density lipoprotein - cholesterol (LDL-C) - levels are not included, as well as a variety of strong predictors used in other risk-stratification scores: previous myocardial infarction, heart failure, smoking, family history, etc. However, the metabolic syndrome identifies additional important residual vascular risk mainly associated with insulin resistance and atherogenic dyslipidemia (low high density lipoprotein-cholesterol (HDL-C), high triglycerides, small, dense LDL-C). Therefore, the metabolic syndrome could be a useful additional contributor in estimation of global cardiovascular risk beyond age, high LDL-C or other standard risk factors. The components of the metabolic syndrome have partially overlapping mechanisms of pathogenic actions mediated through common metabolic pathways. Therefore their total combined effect could be less than the summed of the individual effects. The concept that the metabolic syndrome is a consequence of obesity and insulin resistance, provides a useful "life-style changes" approach for prevention and treatment: caloric restriction, weight-loss and increased physical activity. The next step could theoretically be pharmacological interventions such as metformin, acarbose, fibrates, weight-loss drugs (currently only orlistat is practically available) and perhaps glucagon-like peptide-1 agonists. A third step should probably be kept for bariatric surgery.
doi:10.1186/1475-2840-10-11
PMCID: PMC3036609  PMID: 21269524
2.  The ubiquitous interleukin-6: a time for reappraisal 
Interleukin-6 (IL-6) is a multifunctional cytokine regulating humoral and cellular responses and playing a central role in inflammation and tissue injury. Its effects are mediated through interaction with its receptor complex, IL-6Rβ (also known as gp130). It plays an important role in the pathogenesis of coronary artery disease and large quantities of IL-6 are found in human atherosclerotic plaques. IL-6 levels positively correlate with higher all-cause mortality, unstable angina, left ventricular dysfunction, propensity to diabetes and its complications, hypertension, obesity and several types of cancer. IL-6 levels augmentation demonstrates a remarkable parallel with another biomarkers reflecting harmful processes, like tumor necrosis factor alpha, interleukins 8 and 18, YKL-40, C reactive protein and resistin. Due to these facts, IL-6 was classified as a noxious interleukin. Nonetheless, there are several facts that challenge this usually accepted point of view. Since IL-6 has also anti-inflammatory activity, it seems reasonable to assume that favorable aspects exist. These aspects are two: 1. protection against bacterial infections, inactivating proinflammatory mediators, mitigating the course of septic shock and inducing the production of cortisol; and 2. influence on insulin sensitivity during exercise; this aspect is even more important. During exercise IL-6 is synthesized and released by muscles, with enhanced insulin action immediately at early recovery. Skeletal muscle may be considered as an endocrine organ; contracting muscles produce IL-6 and release it into the blood exerting its effects on other organs. The increase in circulating levels of IL-6 after exercise is consistent and proportional to exercise duration, intensity, muscle mass involved and endurance capacity. Thus, the fascinating possibility that the plenteous beneficial health effects of exercise could be ultimately mediated by IL-6 merits further elucidation. Interleukins were termed "good" or "bad", probably due to a tendency to see things in black and white, with no gray area in between. Calling IL-6 "a molecule with both beneficial and destructive potentials" would be a more equitable approach. In the literary creatures of Dr. Jekyll and Mr. Hyde, a good and an evil personality are found in the same individual. IL-6 playing the role of Dr. Jekyll is emerging; the time for IL-6 reappraisal is coming.
doi:10.1186/1475-2840-9-62
PMCID: PMC2959009  PMID: 20937099
3.  Statins research unfinished saga: desirability versus feasibility 
Drugs in the same class are generally thought to be therapeutically equivalent because of similar mechanisms of action (the so-called "class effect"). However, statins differ in multiple characteristics, including liver and renal metabolism, half-life, effects on several serum lipid components, bioavailability and potency. Some are fungal derivatives, and others are synthetic compounds. The percentage absorption of an oral dose, amount of protein binding, degree of renal excretion, hydrophilicity, and potency on a weight basis is variable. These differences may be even greater in diabetic patients, who may present diabetes-induced abnormalities in P450 isoforms and altered hepatic metabolic pathways. Thus, it is obvious that head-to-head comparisons between different statins are preferable than trial-to-trial comparisons. Such assessments are of utmost importance, especially in cases in which specific populations with a distinct lipid profile and altered metabolic pathways, like diabetics, are studied. It should be specially pinpointed that patients with metabolic syndrome and diabetes constitute also a special population regarding their atherogenic dyslipidemia, which is usually associated with low HDL-cholesterol, hypertriglyceridemia and predominance of small dense LDL-cholesterol. Therefore, these patients may benefit from fibrates or combined statin/fibrate treatment. This policy is not accomplished since in the real world things are more complex. Trials would require very large sample sizes and long-term follow-up to detect significant differences in myocardial infarction or death between two different statins. Moreover, the fact that new compounds are under several phases of research and development represents an additional drawback for performing the trials. Ideally, head-to-head trials regarding clinically important outcomes should be conducted for all drugs. Nonetheless, the desirability of performing such trials, which epitomize modern evidence-based medicine, is frequently superseded by the feasibility dictated by pragmatic and economic circumstances. In the latter case, in absence of solid systematic documentation of comparable health benefits and long-term safety, both researchers and practicing physicians should allude to the weight of scientific endorsement behind the arguments and seek for the possible strengths and weaknesses intrinsic to each specific study. In any case, conclusions based on surrogate endpoints cannot completely substitute head-to-head comparisons regarding patients' outcome.
doi:10.1186/1475-2840-4-8
PMCID: PMC1156921  PMID: 15941471
coronary artery disease; diabetes; hyperlipidemia; statins; trials
4.  Which is the best lipid-modifying strategy in metabolic syndrome and diabetes: fibrates, statins or both? 
Although less clinical intervention studies have been performed with fibrates than with statins, there are evidences indicating that fibrates may reduce risk of cardiovascular events. The potential clinical benefit of the fenofibrate will be specified by the ongoing Fenofibrate Intervention and Event Lowering in Diabetes (FIELD) study, which rationale, methods and aims have been just published.
Controlled clinical trials show similar or even greater cardiovascular benefits from statins-based therapy in patient subgroups with diabetes compared with overall study populations. Therefore, statins are the drug of first choice for aggressive lipid lowering actions and reducing risk of coronary artery disease in these patients. However, current therapeutic use of statins as monotherapy is still leaving many patients with mixed atherogenic dyslipidemia at high risk for coronary events. A combination statin/fibrate therapy may be often necessary to control all lipid abnormalities in patients with metabolic syndrome and diabetes adequately, since fibrates provide additional important benefits, particularly on triglyceride and HDL-cholesterol levels. Thus, this combined therapy concentrates on all the components of the mixed dyslipidemia that often occurs in persons with diabetes or metabolic syndrome, and may be expected to reduce cardiovascular morbidity and mortality.
Safety concerns about some fibrates such as gemfibrozil may lead to exaggerate precautions regarding fibrate administration and therefore diminish the use of the seagents. However, other fibrates, such as bezafibrate and fenofibrate appear to be safer and better tolerated. We believe that a proper co-administration of statins and fibrates, selected on basis of their safety, could be more effective in achieving a comprehensive lipid control as compared with monotherapy.
doi:10.1186/1475-2840-3-10
PMCID: PMC538252  PMID: 15574199
Diabetes mellitus; Dyslipidemia; Fibrates; Metabolic syndrome; Statins

Results 1-4 (4)