In 2013, the American Heart Association and American College of Cardiology published the “Guideline on Lifestyle Management to Reduce Cardiovascular Risk,” which was based on a systematic review originally initiated by the National Heart, Lung, and Blood Institute. The guideline supports the American Heart Association’s 2020 Strategic Impact Goals for cardiovascular health promotion and disease reduction by providing more specific details for adopting evidence-based diet and lifestyle behaviors to achieve those goals. In addition, the
2015–2020 Dietary Guidelines for Americans
issued updated evidence relevant to reducing cardiovascular risk and provided additional recommendations for adopting healthy diet and lifestyle approaches. This scientific statement, intended for healthcare providers, summarizes relevant scientific and translational evidence and offers practical tips, tools, and dietary approaches to help patients/clients adapt these guidelines according to their sociocultural, economic, and taste preferences.
Marked improvement in glycemic control occurs in patients with type 2 diabetes mellitus shortly after Roux-en-Y gastric bypass surgery (RYGB) and before there is major weight loss. The objective of this study was to determine whether the magnitude of this change is primarily due to caloric restriction or is unique to the surgical procedure. We studied eleven subjects who underwent RYGB and fourteen subjects mean-matched for BMI, HbA1c, and diabetes duration who were admitted to our inpatient research unit and given a very low–calorie diet (VLCD) of 500 kcal/day with a macronutrient content similar to that consumed by patients after RYGB. Frequently sampled intravenous glucose tolerance tests were performed before and after interventions. Both groups lost an equivalent amount of weight over a mean study period of 21 days. Insulin sensitivity, acute insulin secretion after intravenous glucose administration, and β-cell function as determined by disposition index improved to a similar extent in both groups. Likewise, changes in fasting glucose and fructosamine levels were similar. Based on these data, VLCD improves insulin sensitivity and β-cell function just as well as RYGB in the short term.
Background
Alirocumab, a monoclonal antibody to proprotein convertase subtilisin/kexin type 9 (PCSK9), lowers plasma low density lipoprotein cholesterol (LDL-C) and apolipoprotein B100 (apoB). Although studies in mice and cells have identified increased hepatic LDL receptors as the basis for LDL lowering by PCSK9 inhibitors, there have been no human studies characterizing the effects of PCSK9 inhibitors on lipoprotein metabolism. In particular, it is not known if inhibition of PCSK9 has any effects on very low density lipoprotein (VLDL) or intermediate density lipoprotein (IDL) metabolism. Inhibition of PCSK9 also results in reductions of plasma Lp(a) levels. The regulation of plasma Lp(a) levels, including the role of LDL receptors (LDLRs) in the clearance of Lp(a), is poorly defined, and there have been no mechanistic studies of the Lp(a) lowering by alirocumab in humans.
Methods
Eighteen (10F, 8M) participants completed a placebo-controlled, two-period study. They received 2 doses of placebo, 2 weeks apart, followed by 5 doses of 150 mg of alirocumab, 2 weeks apart. At the end of each period, fractional clearance rates (FCR) and production rates (PR) of apoB and apo(a) were determined. In 10 participants, postprandial triglycerides (TG) and apoB48 levels were measured.
Results
Alirocumab reduced ultracentrifugally isolated LDL-C by 55.1%, LDL-apoB by 56.3%, and plasma Lp(a) by 18.7%. The fall in LDL-apoB was due to an 80.4% increase in LDL-apoB FCR and a 23.9% reduction in LDL-apoB PR. The latter was associated with a 46.1% increase in IDL-apoB FCR coupled with a 27.2% decrease in conversion of IDL to LDL. The FCR of apo(a) tended to increase (24.6%) without any change in apo(a) PR. Alirocumab had no effects on FCRs or PRs of VLDL-apoB and VLDL-TG, or on postprandial plasma TG or apoB48 concentrations.
Conclusions
Alirocumab decreased LDL-C and LDL-apoB by increasing IDL- and LDL-apoB FCRs, and decreasing LDL-apoB PR. These results are consistent with increases in LDLRs available to clear IDL and LDL from blood during PCSK9 inhibition. The possible increase in apo(a) FCR during alirocumab treatment suggests that increased LDLRs may also play a role in the reduction of plasma Lp(a).
Clinical Trials Registration
Clinical trials.gov # NCT01959971
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