Pharmacological management of high triglycerides and low high-density lipoprotein cholesterol

Jabuticaba (Plinia trunciflora (O. Berg) Kausel) improved the lipid profile and immune system and reduced oxidative stress in streptozotocin-induced diabetic rats

The aim of this study was evaluating the effects of jabuticaba aqueous extract (JPE - 0.5 g/kg) on serum lipid levels, immune system, and oxidative stress parameters of streptozotocin-induced diabetic rats. Administration of JPE for 30 days, by gavage, was able to reduce serum levels of total cholesterol, non-high density lipoprotein (HDL) cholesterol, and triglycerides in diabetic rats. The HDL cholesterol levels increased in both diabetic and healthy rats after JPE treatment. Total leukocyte and lymphocyte counts reduced in diabetic rats, and JPE treatment prevented these diabetes mellitus (DM)-induced changes in the immune system. In addition, the induction of DM also led to dysregulation in the activity of superoxide dismutase and catalase antioxidant enzymes as well as an increase in oxidative stress markers. Treatments with JPE reduced oxidative stress and modulated antioxidant enzyme activities. These data demonstrate the potential of JPE as an adjuvant treatment option for diabetic patients. PRACTICAL APPLICATIONS: Considering that it is very common to observe dyslipidemia in diabetic patients and that these alterations, combined with the increased oxidative stress levels, also common in these patients, can lead to the development of cardiovascular diseases, JPE would be an alternative treatment adjunct to reduce these risks. In addition, although more studies are needed, JPE has the potential to improve the count of total lymphocytes and leukocytes, which could assist in improving the immune response of these patients, who also commonly have a higher risk of infectious diseases. Thus, JPE could be used by these patients, in combination with conventional treatment, in the form of a nutraceutical rich in phenolic compounds.

Lipid-lowering effect of Pinus sp. sawdust and Pycnoporus sanguineus mycelium in streptozotocin-induced diabetic rats

The purpose of this study was to investigate the effect of diet supplementations on biochemical, hematological, and redox metabolism parameters in streptozotocin-induced diabetic rats. Healthy male Wistar rats and streptozotocin-induced diabetic rats were provided diets supplemented with 20% of Pinus sp. sawdust or Pycnoporus sanguineus mycelium for 4 weeks. Diabetic rats treated with both Pinus sp. sawdust- and P. sanguineus mycelium-supplemented diets presented a significant decrease in non-HDL cholesterol of 38.43% and 33.53% and triglycerides of 70.03% and 69.81%, respectively, compared to diabetic control. As far as we know, this is the first report of a significant decrease in serum lipids attributed to these supplementations. Even though with the alterations in hematological and redox metabolism parameters related to these diet treatments, our data suggest that Pinus sp. sawdust and Pycnoporus sanguineus mycelium could be a useful a diet supplement to control diabetic dyslipidemia in animals. PRACTICAL APPLICATIONS: Pinus sp. sawdust is a residue from the wood industry that can be reused as a substrate to cultivate Pycnoporus sanguineus mycelium. Both species have specific and rich natural compounds. The results of the present study surprisingly showed that diets supplemented with the isolated substrate (Pinus sp. sawdust) and Pycnoporus sanguineus mycelium significantly decrease non-HDL cholesterol and triglycerides in induced diabetic animal model. These new natural approaches can be interesting to develop a nutraceutical to treat dyslipidemia.

Assessment of Compliance with Lipid Guidelines in an Academic Medical Center

Background:

The importance of achieving a low-density lipoprotein cholesterol (LDL-C) level less than 100 mg/dL in patients with coronary artery disease (CAD) or cerebrovascular disease (CVD) is well established. Emerging evidence supports the recognition and management of secondary lipid goals, high-density lipoprotein cholesterol (HDL-C) level greater than 40 mg/dL, and triglyceride level less than 150 mg/dL.

Objective:

To evaluate whether inpatient services within an academic setting were achieving/addressing primary and secondary lipid goals in patients with established CAD or CVD.

Methods:

Patients with a discharge diagnosis of acute myocardial infarction, myocardial revascularization procedures, and/or ischemic stroke were identified. A retrospective chart review was done to assess adherence to the American Heart Association (AHA)/American College of Cardiology (ACC) guidelines for lipid management.

Results:

On average, 63% of patients with CAD or CVD had a lipid panel assessed during their hospitalization. Of the patients who had a fasting lipid panel checked, only 40% (72/178) had an LDL-C level less than 100 mg/dL. Of those patients, only 31% (22) also had an HDL-C level greater than 40 mg/dL. Even fewer patients (24%; 17) met both primary and secondary goals. Of the 287 patients included in the study, 69% (199) were prescribed a statin, 3% (9) a fibrate, and 3% (8) niacin on discharge.

Conclusions:

Few patients with CAD or CVD met the AHA/ACC goals for lipid management, yet a significant number were not prescribed appropriate lipid-lowering therapy at discharge. This finding strongly suggests that more awareness in this area is needed.

[Consecutive formation of the functions of high-, low-density and very-low-density lipoproteins during phylogenesis. Unique algorithm of the effects of lipid-lowering drugs]

During phylogenesis, all fatty acids (FA) were initially transported to cells by apoA-I high-density lipoproteins (HDL) in polar lipids. Later, active cellular uptake of saturated, monoenoic and unsaturated FA occurred via triglycerides (TG) in low-density lipoproteins (LDL). Active uptake of polyenoic FA (PUFA) required the following: a) PUFA re-esterified from polar phospholipids into nonpolar cholesteryl polyesters (poly-CLE), b) a novel protein, cholesteryl ester transfer protein (CETP), initiated poly-CLE transformation from HDL to LDL. CETP formed blood HDL-CETP-LDL complexes in which poly-CLE spontaneously came from polar lipids of TG in HDL to nonpolar TG in LDL. Then ligand LDLs formed and the cells actively absorbed PUFA via apoB-100 endocytosis. Some animal species (rats, mice, dogs) developed a spontaneous CETP-minus mutation followed by population death from atherosclerosis. However, there was another active CETP-independent uptake formed during phylogenesis; the cells internalized poly-CLE in HDL. Since apoA-I had no domain-ligand, another apoE/A-I ligand formed; the cells began synthesizing apoE/A-1 receptors. In cells of rabbits and primates absorbed cells PUFA consecutively: HDL-->LDL-->apoB-100 endocytosis; those of rats and dogs did HDL directly: HDL-->anoE/A-I endocytosis. In the rabbits, CETP was high, apoE in HDL was low, and the animals were sensitive to exogenous hypercholesterolemia. In the rats, CETP was low and ApoE in HDL-was high, and the animals were resistant to hypercholesterolemia. Reduced bioavailability of PUFA during their consecutive cellular uptake and develdpment of intercellular PUFA deficiency are fundamental to the pathogenesis of atherosclerosis.

Niacin, an old drug with a new twist

Niacin (nicotinic acid) has been used for decades as a lipid-lowering drug. The clinical use of niacin to treat dyslipidemic conditions is limited by its side effects. Niacin, along with fibrates, are the only approved drugs which elevate high density lipoprotein cholesterol (HDLc) along with its effects on low density lipoprotein cholesterol (LDLc) and triglycerides. Whether niacin has a beneficial role in lowering cardiovascular risk on the background of well-controlled LDLc has not been established. In fact, it remains unclear whether niacin, either in the setting of well-controlled LDLc or in combination with other lipid-lowering agents, confers any therapeutic benefit and if so, by which mechanism. The results of recent trials reject the hypothesis that simply raising HDLc is cardioprotective. However, in the case of the clinical trials, structural limitations of trial design complicate their interpretation. This is also true of the most recent Heart Protection Study 2-Treatment of HDLc to Reduce the Incidence of Vascular Events (HPS2-THRIVE) trial in which niacin is combined with an antagonist of the D prostanoid (DP) receptor. Human genetic studies have also questioned the relationship between cardiovascular benefit and HDLc. It remains to be determined whether niacin may have clinical utility in particular subgroups, such as statin intolerant patients with hypercholesterolemia or those who cannot achieve a sufficient reduction in LDLc. It also is unclear whether a potentially beneficial effect of niacin is confounded by DP antagonism in HPS2-THRIVE.

Apolipoprotein E genotype as a most significant predictor of lipid response at lipid-lowering therapy: mechanistic and clinical studies

APOE alleles and apolipoprotein E isoforms control plasma cholesterol level on population level. Among three ɛ2, ɛ3, ɛ4 alleles, ɛ4 allele is associated with the increase in cholesterol level, risk of atherosclerosis and Alzheimer disease, while ɛ2 allele is associated with the decrease in cholesterol level and risk of atherosclerosis. The increase in plasma triglyceride is an independent risk factor of atherosclerosis and triglyceride-high density lipoprotein coupling determines the efficiency of reverse cholesterol transport. The impairment of this coupling specifically at hypertriglyceridemia may be followed by specific lipoprotein markers. The influence of major lipid-lowering drugs on lipoprotein metabolism and association of apoE isoforms with the efficiency of therapy by statins and fibrates are summarized both at isolated and combined increase in plasma triglyceride and cholesterol. APOE polymorphism seems to be a single genetic variant with a confirmed stratification both at candidate gene and at wide genome analyses.

Weight and metabolic outcomes after 2 years on a low-carbohydrate versus low-fat diet: a randomized trial

BACKGROUND

Previous studies comparing low-carbohydrate and low-fat diets have not included a comprehensive behavioral treatment, resulting in suboptimal weight loss.

OBJECTIVE

To evaluate the effects of 2-year treatment with a low-carbohydrate or low-fat diet, each of which was combined with a comprehensive lifestyle modification program.

DESIGN

Randomized parallel-group trial. (ClinicalTrials.gov registration number: NCT00143936)

SETTING

3 academic medical centers.

PATIENTS

307 participants with a mean age of 45.5 years (SD, 9.7 years) and mean body mass index of 36.1 kg/m(2) (SD, 3.5 kg/m(2)).

INTERVENTION

A low-carbohydrate diet, which consisted of limited carbohydrate intake (20 g/d for 3 months) in the form of low-glycemic index vegetables with unrestricted consumption of fat and protein. After 3 months, participants in the low-carbohydrate diet group increased their carbohydrate intake (5 g/d per wk) until a stable and desired weight was achieved. A low-fat diet consisted of limited energy intake (1200 to 1800 kcal/d; <or=30% calories from fat). Both diets were combined with comprehensive behavioral treatment.

MEASUREMENTS

Weight at 2 years was the primary outcome. Secondary measures included weight at 3, 6, and 12 months and serum lipid concentrations, blood pressure, urinary ketones, symptoms, bone mineral density, and body composition throughout the study.

RESULTS

Weight loss was approximately 11 kg (11%) at 1 year and 7 kg (7%) at 2 years. There were no differences in weight, body composition, or bone mineral density between the groups at any time point. During the first 6 months, the low-carbohydrate diet group had greater reductions in diastolic blood pressure, triglyceride levels, and very-low-density lipoprotein cholesterol levels, lesser reductions in low-density lipoprotein cholesterol levels, and more adverse symptoms than did the low-fat diet group. The low-carbohydrate diet group had greater increases in high-density lipoprotein cholesterol levels at all time points, approximating a 23% increase at 2 years.

LIMITATION

Intensive behavioral treatment was provided, patients with dyslipidemia and diabetes were excluded, and attrition at 2 years was high.

CONCLUSION

Successful weight loss can be achieved with either a low-fat or low-carbohydrate diet when coupled with behavioral treatment. A low-carbohydrate diet is associated with favorable changes in cardiovascular disease risk factors at 2 years.

PRIMARY FUNDING SOURCE

National Institutes of Health.

Phenolic acids suppress adipocyte lipolysis via activation of the nicotinic acid receptor GPR109A (HM74a/PUMA-G)

Phenolic acids are found in abundance throughout the plant kingdom. Consumption of wine or other rich sources of phenolic acids, such as the "Mediterranean diet," has been associated with a lower risk of cardiovascular disease. The underlying mechanism(s), however, has remained unclear. Here, we show that many phenolic acids, including those from the hydroxybenzoic and hydroxycinnamic acid classes, can bind and activate GPR109A (HM74a/PUMA-G), the receptor for the antidyslipidemic agent nicotinic acid. In keeping with this activity, treatment with a number of phenolic acids, including cinnamic acid, reduces lipolysis in cultured human adipocytes and in fat pats isolated from wild-type mice but not from mice deficient of GPR109A. Oral administration of cinnamic acid significantly reduces plasma levels of FFA in the wild type but not in mice deficient of GPR109A. Activation of GPR109A by phenolic acids may thus contribute to a cardiovascular benefit of these plant-derived products.

The psoriasis drug monomethylfumarate is a potent nicotinic acid receptor agonist

Nicotinic acid has been used for several decades to treat dyslipidemia. In mice, the lipid-lowing effect of nicotinic acid is mediated by the Gi coupled receptor PUMA-G. In humans, high (GPR109A) and low (GPR109B) affinity nicotinic acid receptors have been characterized. Here we identify monomethylfumarate as a GPR109A agonist. Monomethylfumarate is the active metabolite of the psoriasis drug Fumaderm. We show that monomethylfumarate activates GPR109A in a calcium based aequorin assay, cAMP assay and demonstrate competitive binding with nicotinic acid. We show that GPR109A is highly expressed in neutrophils and epidermal keratinocytes, and that its expression is increased in human psoriatic lesions. Our findings provide evidence that GPR109A is a target for the drug Fumaderm and suggest that niacin should be investigated to treat psoriasis in addition to its role in treating lipid disorders.

Nicotinic acid: pharmacological effects and mechanisms of action

Pharmacological doses of nicotinic acid induce a profound change in the plasma levels of various lipids and lipoproteins. The ability of nicotinic acid to strongly increase the plasma concentration of high-density lipoprotein (HDL) cholesterol has in recent years led to an increased interest in the pharmacological potential of nicotinic acid. There is increasing evidence that nicotinic acid alone or in addition to LDL cholesterol-lowering drugs can reduce the progression of atherosclerosis and reduce the risk of cardiovascular events. The clinical use of nicotinic acid is, however, hindered by harmless but unpleasant side effects, especially by a strong cutaneous vasodilation called flushing. The recent discovery of the G protein-coupled receptor GPR109A (HM74A or PUMA-G) as a receptor for nicotinic acid has allowed for better understanding of the mechanisms underlying the metabolic and vascular effects of nicotinic acid. On the basis of recent progress in understanding the pharmacological effects of nicotinic acid, new strategies are in development to better exploit the pharmacological potential of nicotinic acid. New drugs acting via the nicotinic acid receptor or related receptors, as well as new co-medications that suppress unwanted effects of nicotinic acid, will most likely be introduced as new therapeutic options in the treatment of dyslipidemia and the prevention of cardiovascular diseases.

Nicotinic acid: an old drug with a promising future

Nicotinic acid has been used for decades to treat dyslipidaemic states. In particular its ability to raise the plasma HDL cholesterol concentration has led to an increased interest in its pharmacological potential. The clinical use of nicotinic acid is somewhat limited due to several harmless but unpleasant side effects, most notably a cutaneous flushing phenomenon. With the recent discovery of a nicotinic acid receptor, it has become possible to better understand the mechanisms underlying the metabolic and vascular effects of nicotinic acid. Based on these new insights into the action of nicotinic acid, novel strategies are currently under development to maximize the pharmacological potential of this drug. The generation of both flush-reducing co-medications of nicotinic acid and novel drugs targeting the nicotinic acid receptor will provide future therapeutic options for the treatment of dyslipidaemic disorders.

Human epidermoid A431 cells express functional nicotinic acid receptor HM74a

Nicotinic acid (niacin) has been used clinically to manage dyslipidemia for many years. The molecular target of nicotinic acid was unknown until the recent revelation of human G-coupled receptor HM74a as the high affinity receptor for nicotinic acid. In searching for a cell line expressing endogenous human HM74a receptor, we have identified that the A431 cell line, a human epidermoid cell line, expresses a high level of HM74a receptor. An HM74a-specific real time PCR probe set was designed and the mRNA levels of HM74a in A431 and 32 other cultured cell lines were measured quantitatively. When the mRNA expression of HM74a in A431 cells was compared to that in human primary preadipocytes, adipocytes and adipose tissue, we found that the level in A431 was about 10- fold higher than that in adipocytes and adipose tissue. The ratio of HM74a:HM74 mRNA was measured quantitatively and it was determined to be 3:2 in A431 cells. The function of the HM74a receptor in A431 cells was evaluated for its ability to inhibit forskolin-induced cAMP production. Pertussis toxin treatment abolished the inhibition. Our data suggest that the A431 cell line may serve as a cellular model for further investigation of niacin/HM74a-mediated signal transduction in modulating metabolism. A431 cell line may also provide a valuable cell model to study prostaglandin production upon HM74a activation to improve our understanding of niacin/HM74a-mediated skin flushing.

GPR109A (PUMA-G/HM74A) mediates nicotinic acid-induced flushing

Nicotinic acid (niacin) has long been used as an antidyslipidemic drug. Its special profile of actions, especially the rise in HDL-cholesterol levels induced by nicotinic acid, is unique among the currently available pharmacological tools to treat lipid disorders. Recently, a G-protein-coupled receptor, termed GPR109A (HM74A in humans, PUMA-G in mice), was described and shown to mediate the nicotinic acid-induced antilipolytic effects in adipocytes. One of the major problems of the pharmacotherapeutical use of nicotinic acid is a strong flushing response. This side effect, although harmless, strongly affects patient compliance. In the present study, we show that mice lacking PUMA-G did not show nicotinic acid-induced flushing. In addition, flushing in response to nicotinic acid was also abrogated in the absence of cyclooxygenase type 1, and mice lacking prostaglandin D(2) (PGD(2)) and prostaglandin E(2) (PGE(2)) receptors had reduced flushing responses. The mouse orthologue of GPR109A, PUMA-G, is highly expressed in macrophages and other immune cells, and transplantation of wild-type bone marrow into irradiated PUMA-G-deficient mice restored the nicotinic acid-induced flushing response. Our data clearly indicate that GPR109A mediates nicotinic acid-induced flushing and that this effect involves release of PGE(2) and PGD(2), most likely from immune cells of the skin.

FR177391, A New Anti-hyperlipidemic Agent from Serratia

The pharmacological effect of FR177391, isolated from Serratia liquefaciens No. 1821, was studied in normal animals and various types of animal models of hypertriglyceridemia. Treatment of normal mice with FR177391 resulted in an increase in heparin-releasable lipoprotein lipase (LPL) activity in the blood and epididymal fat tissue. FR177391 treatment decreased triglyceride (TG) and increased high-density lipoprotein cholesterol in the blood in normal rats following 7 days treatment, suggesting potent LPL activating properties of FR177391. Both Triton WR1339-induced severe and fructose-induced mild hypertriglyceridemia in rats were attenuated by FR177391 treatment. Severely elevated levels of TG in db/db mice, an insulin resistant diabetic animal model, also significantly decreased from 14 days of treatment with FR177391. FR177391 treatment for 9 days caused a decrease in the elevated levels of TG in mice induced by intraperitoneal inoculation of murine lymphoma EL-4. Overall, this study demonstrated that FR177391 can be possibly a LPL activating agent and that FR177391 treatment improved hypertriglyceridemia in various rat and mouse animal models. These results suggest that FR177391 is a promising candidate compound for the management of hypertriglyceridemia.

Herbal or natural medicines as modulators of peroxisome proliferator-activated receptors and related nuclear receptors for therapy of metabolic syndrome

The use of herbal or natural medicines for the treatment of various disorders has a long and extensive history. Many of these herbal medicines are finding their way onto the world market as alternatives to prescribed drugs currently available to treat various disorders/ailments. In particular, hyperlipidaemia is a major risk factor for atherosclerotic coronary vascular disease, which can culminate in mortality in diabetes mellitus. There is overwhelming evidence that patients with type 2 diabetes mellitus often have metabolic syndrome and require a multifactorial intervention including aggressive treatment of arterial hypertension and dyslipidaemia to prevent cardiovascular complications. One of the most active areas of metabolic research into potential treatments is in the role of nuclear receptors as therapeutic targets for both glucose and lipid metabolism. The purpose of this review is to highlight the recent advances made by pharmaceutical and research organizations in identifying biologically active compounds from natural plant products capable of modulating nuclear receptors such as peroxisome proliferator-activated receptors and, to a lesser extent, liver X receptor and farnesoid X receptor. The specific features presented by these receptors provide an in-depth insight into the pathogenesis of metabolic disease and thus, a means of establishing potential mechanisms of action with traditional medicine. In hindsight, the review offers valuable information for rational drug design using known active compounds of plant origin. Further research may ultimately lead to a reduction in both the chronic microvascular complications of type 2 diabetes mellitus and the risk of cardiovascular disease and metabolic syndrome with the use of traditional medicine.

Long-term effects of a high-protein, low-carbohydrate diet on weight control and cardiovascular risk markers in obese hyperinsulinemic subjects

OBJECTIVE

To compare the long-term compliance and effects of two low-fat diets differing in carbohydrate to protein ratio on body composition and biomarkers of cardiovascular disease risk in obese subjects with hyperinsulinemia.

DESIGN

Outpatient, parallel, clinical intervention study of two groups of subjects randomly assigned to either a standard protein (SP; 15% protein, 55% carbohydrate) or high-protein (HP; 30% protein, 40% carbohydrate) diet, during 12 weeks of energy restriction (approximately 6.5 MJ/day) and 4 weeks of energy balance (approximately 8.3 MJ/day). Subsequently, subjects were asked to maintain the same dietary pattern for the succeeding 52 weeks with minimal professional support.

SUBJECTS

A total of 58 obese, nondietetic subjects with hyperinsulinemia (13 males/45 females, mean age 50.2 y, mean body mass index (BMI) 34.0 kg/m2, mean fasting insulin 17.8 mU/l) participated in the study.

MEASUREMENTS

: Body composition, blood pressure, blood lipids, fasting glucose, insulin, CRP and sICAM-1 were measured at baseline and at weeks 16 and 68. Urinary urea/creatinine ratio was measured at baseline, week 16 and at 3 monthly intervals thereafter.

RESULTS

In total, 43 subjects completed the study with similar dropouts in each group (P=0.76). At week 68, there was net weight loss (SP -2.9+/-3.6%, HP -4.1+/-5.8%; P<0.44) due entirely to fat loss (P<0.001) with no diet effect [corrected]. Both diets significantly increased HDL cholesterol concentrations (P<0.001) and decreased fasting insulin, insulin resistance, sICAM-1 and CRP levels (P<0.05). Protein intake was significantly greater in HP during the initial 16 weeks (P<0.001), but decreased in HP and increased in SP during 52-week follow-up, with no difference between groups at week 68, indicating poor long-term dietary adherence behaviour to both dietary patterns.

CONCLUSION

Without active ongoing dietary advice, adherence to dietary intervention is poor. Nonetheless, both dietary patterns achieved net weight loss and improvements in cardiovascular risk factors.

Physical activity and its effects on lipids

Physical activity is an important component of weight control, and is widely recommended to prevent and treat obesity-related complications such as diabetes and coronary heart disease (CHD). Although the cardiovascular benefits of increased physical activity are likely multifactorial, much of the attention has been focused on the known high-density lipoprotein (HDL) cholesterol-raising properties of regular physical activity. Physical activity, however, can also reliably lower triglycerides and favorably affect both low-density lipoprotein (LDL) and HDL particle sizes. Limited data on resistance exercise suggest that this type of physical activity may reduce LDL cholesterol. Although these lipid effects are modest and variable, they are likely to be particularly important in reducing the morbidity and mortality from CHD on a population level, and may be especially important in patients with atherogenic dyslipidemia.

A randomized trial of a low-carbohydrate diet for obesity

BACKGROUND

Despite the popularity of the low-carbohydrate, high-protein, high-fat (Atkins) diet, no randomized, controlled trials have evaluated its efficacy.

METHODS

We conducted a one-year, multicenter, controlled trial involving 63 obese men and women who were randomly assigned to either a low-carbohydrate, high-protein, high-fat diet or a low-calorie, high-carbohydrate, low-fat (conventional) diet. Professional contact was minimal to replicate the approach used by most dieters.

RESULTS

Subjects on the low-carbohydrate diet had lost more weight than subjects on the conventional diet at 3 months (mean [+/-SD], -6.8+/-5.0 vs. -2.7+/-3.7 percent of body weight; P=0.001) and 6 months (-7.0+/-6.5 vs. -3.2+/-5.6 percent of body weight, P=0.02), but the difference at 12 months was not significant (-4.4+/-6.7 vs. -2.5+/-6.3 percent of body weight, P=0.26). After three months, no significant differences were found between the groups in total or low-density lipoprotein cholesterol concentrations. The increase in high-density lipoprotein cholesterol concentrations and the decrease in triglyceride concentrations were greater among subjects on the low-carbohydrate diet than among those on the conventional diet throughout most of the study. Both diets significantly decreased diastolic blood pressure and the insulin response to an oral glucose load.

CONCLUSIONS

The low-carbohydrate diet produced a greater weight loss (absolute difference, approximately 4 percent) than did the conventional diet for the first six months, but the differences were not significant at one year. The low-carbohydrate diet was associated with a greater improvement in some risk factors for coronary heart disease. Adherence was poor and attrition was high in both groups. Longer and larger studies are required to determine the long-term safety and efficacy of low-carbohydrate, high-protein, high-fat diets.

PUMA-G and HM74 are receptors for nicotinic acid and mediate its anti-lipolytic effect

Nicotinic acid (niacin), a vitamin of the B complex, has been used for almost 50 years as a lipid-lowering drug. The pharmacological effect of nicotinic acid requires doses that are much higher than those provided by a normal diet. Its primary action is to decrease lipolysis in adipose tissue by inhibiting hormone-sensitive triglyceride lipase. This anti-lipolytic effect of nicotinic acid involves the inhibition of cyclic adenosine monophosphate (cAMP) accumulation in adipose tissue through a G(i)-protein-mediated inhibition of adenylyl cyclase. A G-protein-coupled receptor for nicotinic acid has been proposed in adipocytes. Here, we show that the orphan G-protein-coupled receptor, 'protein upregulated in macrophages by interferon-gamma' (mouse PUMA-G, human HM74), is highly expressed in adipose tissue and is a nicotinic acid receptor. Binding of nicotinic acid to PUMA-G or HM74 results in a G(i)-mediated decrease in cAMP levels. In mice lacking PUMA-G, the nicotinic acid-induced decrease in free fatty acid (FFA) and triglyceride plasma levels was abrogated, indicating that PUMA-G mediates the anti-lipolytic and lipid-lowering effects of nicotinic acid in vivo. The identification of the nicotinic acid receptor may be useful in the development of new drugs to treat dyslipidemia.