ADAM19 cleaves the PTH receptor and associates with brachydactyly type E.

Brachydactyly type E (BDE), shortened metacarpals, metatarsals, cone-shaped epiphyses, and short stature commonly occurs as a sole phenotype. Parathyroid hormone-like protein (PTHrP) has been shown to be responsible in all forms to date, either directly or indirectly. We used linkage and then whole genome sequencing in a small pedigree, to elucidate BDE and identified a truncated disintegrin-and-metalloproteinase-19 (ADAM19) allele in all affected family members, but not in nonaffected persons. Since we had shown earlier that the extracellular domain of the parathyroid hormone receptor (PTHR1) is subject to an unidentified metalloproteinase cleavage, we tested the hypothesis that ADAM19 is a sheddase for PTHR1. WT ADAM19 cleaved PTHR1, while mutated ADAM-19 did not. We mapped the cleavage site that we verified with mass spectrometry between amino acids 64-65. ADAM-19 cleavage increased Gq and decreased Gs activation. Moreover, perturbed PTHR1 cleavage by ADAM19 increased ß-arrestin2 recruitment, while cAMP accumulation was not altered. We suggest that ADAM19 serves as a regulatory element for PTHR1 and could be responsible for BDE. This sheddase may affect other PTHrP or PTH-related functions.

Avoidance of the Ames test liability for aryl-amines via computation.

Aryl-amines are commonly used synthons in modern drug discovery, however a minority of these chemical templates have the potential to cause toxicity through mutagenicity. The toxicity mostly arises through a series of metabolic steps leading to a reactive electrophilic nitrenium cation intermediate that reacts with DNA nucleotides causing mutation. Highly detailed in silico calculations of the energetics of chemical reactions involved in the metabolic formation of nitrenium cations have been performed. This allowed a critical assessment of the accuracy and reliability of using a theoretical formation energy of the DNA-reactive nitrenium intermediate to correlate with the Ames test response. This study contains the largest data set reported to date, and presents the in silico calculations versus the in vitro Ames response data in the form of beanplots commonly used in statistical analysis. A comparison of this quantum mechanical approach to QSAR and knowledge-based methods is also reported, as well as the calculated formation energies of nitrenium ions for thousands of commercially available aryl-amines generated as a watch-list for medicinal chemists in their synthetic optimization strategies.

Improvement of postprandial lipid handling and glucose tolerance in a non-diabetic population by the dual PPARalpha/gamma agonist, tesaglitazar.

This study examined the effect of tesaglitazar (GALIDA), a dual peroxisome proliferator-activated receptor (PPAR)alpha/gamma agonist, on postprandial metabolism. This investigation was part of the Study in Insulin Resistance (SIR) (SH-SBT-0001), a randomised, double-blind, placebo-controlled study that reported improvements in fasting lipid and glucose values with tesaglitazar (0.1, 0.25, 0.5 or 1 mg once daily for 12 weeks) in hypertriglyceridaemic, abdominally obese, non-diabetic patients. A subgroup of 222 patients underwent postprandial lipid and glucose testing at baseline and treatment end. Tesaglitazar 0.25, 0.5 and 1 mg reduced postprandial area under the curve (AUC) for triglycerides by 20% (p=0.003), 30% (p<0.0001) and 41% (p<0.0001), respectively. Free fatty acid (FFA) levels were reduced by 17% with tesaglitazar 0.5 mg (p=0.002) and by 29% with tesaglitazar 1 mg (p<0.0001). Tesaglitazar significantly improved glucose tolerance and increased the proportion of patients with normal glucose tolerance as measured by the oral glucose tolerance test (OGTT). To conclude, postprandial dyslipidaemia and hyperglycaemia, indicators of increased vascular risk, were significantly improved by tesaglitazar treatment in these non-diabetic, hypertriglyceridaemic, abdominally obese subjects.

Effects of switching statins on lipid and apolipoprotein ratios in the MERCURY I study.

BACKGROUND: Lipid ratios are clinically useful markers of coronary artery disease (CAD) risk. The effects of rosuvastatin, atorvastatin, simvastatin, and pravastatin on lipid ratios were investigated in the Measuring Effective Reductions in Cholesterol Using Rosuvastatin TherapY (MERCURY) I trial. METHODS: This trial was conducted in 3140 hypercholesterolemic patients with CAD, atherosclerosis, type 2 diabetes mellitus, or a 20% 10-year risk for CAD. Patients were randomized to rosuvastatin 10 mg, atorvastatin 10 or 20 mg, simvastatin 20 mg, or pravastatin 40 mg for 8 weeks; all patients except those receiving rosuvastatin 10 mg either were switched to rosuvastatin 10 or 20 mg or remained on initial treatment for 8 more weeks. RESULTS: At 8 weeks, reductions in total cholesterol (TC):high-density lipoprotein cholesterol (HDL-C), low-density lipoprotein cholesterol:HDL-C, non-HDL-C:HDL-C, and apolipoprotein (apo) B:apo A-I ratios with rosuvastatin 10 mg were significantly greater than those with atorvastatin 10 mg, atorvastatin 20 mg, simvastatin 20 mg, and pravastatin 40 mg (P<0.0001 for all). At week 16, switching to rosuvastatin 10 mg from atorvastatin 10 mg, simvastatin 20 mg, and pravastatin 40 mg and to rosuvastatin 20 mg from atorvastatin 20 mg produced significantly greater reductions in all lipid ratios (P< or =0.0001 for all). Switching to rosuvastatin 10 mg from atorvastatin 20 mg produced significantly greater reductions in TC:HDL-C (P<0.025) and apo B:apo A-I (P<0.01). CONCLUSIONS: Rosuvastatin 10 mg reduces lipid ratios more than equivalent and higher doses of other statins; switching to equal or lower doses of rosuvastatin produces significantly improved reductions in lipid ratios.

[From phenotype to genotype: a glimpse behind the scenes of an unending story]. / Die Reise vom Phänotyp zum Genotyp.

Mendelian conditions direct attention at basic mechanisms. In the 1990's DNA sequencing allowed elucidating such conditions. We embarked on an unexpected adventure to study a monogenic autosomal-dominant form of hypertension causing also a specific form of short fingers. The gene locus caused a 50 mmHg increase in blood pressure at age of 50. Our clinically based group stumbled to the finish line after 20 years of study. We remained together and proudly persevered. Our findings could be relevant for essential hypertension.

PDE3A mutations cause autosomal dominant hypertension with brachydactyly.

Cardiovascular disease is the most common cause of death worldwide, and hypertension is the major risk factor. Mendelian hypertension elucidates mechanisms of blood pressure regulation. Here we report six missense mutations in PDE3A (encoding phosphodiesterase 3A) in six unrelated families with mendelian hypertension and brachydactyly type E (HTNB). The syndrome features brachydactyly type E (BDE), severe salt-independent but age-dependent hypertension, an increased fibroblast growth rate, neurovascular contact at the rostral-ventrolateral medulla, altered baroreflex blood pressure regulation and death from stroke before age 50 years when untreated. In vitro analyses of mesenchymal stem cell-derived vascular smooth muscle cells (VSMCs) and chondrocytes provided insights into molecular pathogenesis. The mutations increased protein kinase A-mediated PDE3A phosphorylation and resulted in gain of function, with increased cAMP-hydrolytic activity and enhanced cell proliferation. Levels of phosphorylated VASP were diminished, and PTHrP levels were dysregulated. We suggest that the identified PDE3A mutations cause the syndrome. VSMC-expressed PDE3A deserves scrutiny as a therapeutic target for the treatment of hypertension.

The impact of fatty acid oxidation on energy utilization: targets and therapy.

Utilization of fat as a long-term energy storage vehicle is crucial for the maintenance of cellular metabolism and is under intricate and many times redundant control mechanisms. Aberrations in the control of energy metabolism is apparent in diseases such as diabetes and obesity and is evident early on in patients with impaired glucose tolerance. Insulin resistance has been observed at the level of muscle, liver and adipose tissue. Hyperglycemia is the hallmark of diabetes and is characterized by decreased glucose disposal and increased glucose production, driven by enhanced and uncontrolled fatty acid oxidation (FAO). Mechanisms aimed at limiting the availability of substrates or the activity of processes involved in FAO should provide an immediate reduction in undesired glucose production in these individuals. Numerous targets are available which influence directly the metabolism of fat, including limiting availability of substrate to FAO, inhibiting oxidation of the fatty acid per se, and uncoupling the energy obtained during the oxidation of the fatty acid. These include antilipolytic agents which limit the availability of substrate, FAO inhibitors which limit fatty acid transport (carnitine palmitoyl transferase, CoA sequestration), FAO per se (beta oxidation), and agents which uncouple the energy of FAO (uncoupling proteins, beta3 agonists). These other targets which affect fatty acid metabolism indirectly will be discussed in this review with 184 references.

Risk assessment and strategies to achieve lipid goals: lessons from real-world clinical practice.

Coronary heart disease (CHD) risk assessment to establish risk category and appropriate plasma lipid goals as well as achievement of those lipid goals, are important elements of treatment for dyslipidemia in clinical practice. Cases from clinical practice are presented to illustrate risk assessment and treatment in the settings of peripheral arterial disease (PAD) and heterozygous familial hypercholesterolemia (hFH). Patients with PAD are at high risk of CHD and cardiovascular mortality and may require aggressive lipid-lowering therapy irrespective of the degree of hypercholesterolemia at presentation. Risk in patients with hFH is not adequately reflected in population-based risk algorithms. Patients who have hFH should be considered at high risk for developing CHD and given aggressive lipid-modifying therapy, and family screening should be undertaken for additional case finding.

Effects of switching statins on achievement of lipid goals: Measuring Effective Reductions in Cholesterol Using Rosuvastatin Therapy (MERCURY I) study.

BACKGROUND: In a multinational trial (4522IL/0081), we assessed the effects of switching to low doses of rosuvastatin from commonly used doses of atorvastatin, simvastatin, and pravastatin on low-density lipoprotein cholesterol (LDL-C) goal achievement in high-risk patients. METHODS: Hypercholesterolemic patients (n = 3140) with coronary heart disease, atherosclerosis, or type 2 diabetes were randomized to open-label rosuvastatin 10 mg, atorvastatin 10 or 20 mg, simvastatin 20 mg, or pravastatin 40 mg for 8 weeks. Patients either remained on these treatments for another 8 weeks or switched treatments from atorvastatin 10 mg, simvastatin 20 mg, and pravastatin 40 mg to rosuvastatin 10 mg or from atorvastatin 20 mg to rosuvastatin 10 or 20 mg. The primary efficacy measure was the proportion of patients reaching the Joint European Societies' LDL-C goal (<116 mg/dL) at week 16. For measures of cholesterol goal achievement, treatment arms were compared using logistic-regression analysis. RESULTS: Significant improvement in LDL-C goal achievement was found for patients who switched to rosuvastatin 10 mg, compared with patients who remained on atorvastatin 10 mg (86% vs 80%, P <.05), simvastatin 20 mg (86% vs 72%, P <.0001), and pravastatin 40 mg (88% vs 66%, P <.0001), and between patients switched to rosuvastatin 20 mg and those who remained on atorvastatin 20 mg (90% vs 84%, P <.01). Similar results were found for achievement of the European combined LDL-C and total cholesterol goals and National Cholesterol Education Program Adult Treatment Panel III LDL-C goals. All statins were well tolerated over 16 weeks. CONCLUSIONS: We demonstrated that switching to a more efficacious statin is an effective strategy to improve lipid goal achievement in patients requiring lipid-lowering therapy.

DNA testing for familial hypercholesterolemia: improving disease recognition and patient care.

Cardiovascular disease is the leading cause of death worldwide and, like most chronic diseases, it has major genetic and environmental components. Among patients with coronary heart disease onset before the age of 55, about 5% of cases are attributable to heterozygous familial hypercholesterolemia (FH), a disease following autosomal dominant inheritance. About 50% of individuals with FH die before the age of 60 due to myocardial infarction. The frequency of FH is estimated to be 1 : 500. FH is related to mutations in the low-density lipoprotein (LDL)-cholesterol LDL-receptor gene and apolipoprotein B (apoB) gene. The identification of individuals with FH has been based on lipid levels and segregation of lipid levels within the family. However, phenotypes are overlapping and family history is not always informative. Therefore, a DNA-based genetic test for FH appears to offer the best alternative. The DNA test gives a simple yes/no answer. The FH test is a definitive tool for the identification of affected family members. The approach of targeted family genetic screening to find new patients is faster and more reliable compared with a biochemical form of screening. Early identification and efficient treatment of such patients is important and highly cost effective. There is evidence to suggest that the nature of the LDL-receptor (LDLR) mutation influences the degree of cholesterol lowering achieved by HMG-CoA reductase inhibitors (statins). The observed differences in the LDL-cholesterol (LDL-C) responses to these drugs among the various LDLR gene mutations are not yet completely understood. The relationships shown between LDLR mutation types and lipid levels, and the response of lipid levels to HMG-CoA reductase inhibitor treatment, will have to be investigated within the framework of pharmacogenetic studies. The variables, which are important in determining the overall atherosclerosis risk, are the result of combined activity in a dynamic network of numerous genes and environment. Candidate genes for atherosclerosis need to be further tested and validated. Future research should be directed at determining the significance of such targets, which patients with FH are at particularly high risk of premature cardiovascular disease, and which environmental factors are effective in modulating this risk. Genetics-based diagnostics will complement identification of FH while improving cardiovascular risk prediction, prevention of disease and treatment efficacy.

High risk/high priority: familial hypercholesterolemia--a paradigm for molecular medicine.

Familial hypercholesterolemia provides an excellent model for demonstrating how disease prevention can be facilitated by molecular characterization of a genetic disease. To achieve the most efficient yield in terms of patient identification and coronary heart disease prevention, family information should be obtained in the primary care setting. In the majority of cases, measurement of cholesterol levels in a patient's relatives is sufficient to determine presence or absence of familial hypercholesterolemia, and DNA testing may be used in those cases in which cholesterol level is not diagnostic. DNA testing has enabled a more refined assessment of the absolute cardiovascular risks associated with familial hypercholesterolemia, which is currently estimated to have a 50% mortality rate by age 60. Recent investigations using DNA testing have suggested that familial hypercholesterolemia is implicated in one of 12 cases of cardiovascular disease in individuals aged <65 years. Only the most potent lipid-modifying therapies should be used in those found to be affected by this disorder. In this regard, it is noteworthy that the new statin rosuvastatin (Crestor; AstraZeneca) was recently shown to produce significantly greater low-density lipoprotein (LDL) cholesterol reductions and high-density lipoprotein (HDL) cholesterol increases than atorvastatin in a large study in patients with familial hypercholesterolemia, while bringing more of these patients to LDL cholesterol goals. Familial hypercholesterolemia should serve as a paradigm of molecular medicine: we understand the genetic defect, we have the tools to identify the individuals who are at high risk of disease because they have the defect, and we have therapies that can prevent clinical disease. It nevertheless requires effort on the part of clinicians to ensure that optimal risk assessment is performed and optimal treatment provided.

Managing the high-risk patient: therapeutic approaches in 2002.

Populations of patients at high risk of coronary heart disease (CHD) include those with type 2 diabetes and those with heterozygous familial hypercholesterolemia (HeFH). Despite benefits of statin lipid-lowering therapy in reducing CHD risk in diabetic patients, screening for dyslipidemia in such patients is inadequate, and patients frequently fail to achieve recommended low-density lipoprotein goals. Diagnosis of HeFH is also suboptimal, despite the reliability of family lipid screening in confirming clinical diagnosis and utility of screening in identifying other family members who are at risk. Patients with HeFH frequently require large reductions in low-density lipoprotein (LDL) cholesterol to achieve target levels. In both of these populations, statins that produce large reductions in LDL cholesterol offer advantages in achieving lipid-lowering goals and in simplifying medical therapy to reduce CHD risk.

Investigating cardiovascular risk reduction--the Rosuvastatin GALAXY Programme.

The GALAXY Programme is a comprehensive global research initiative that will address several important unanswered questions in statin research and investigate the impact of rosuvastatin on cardiovascular risk reduction and patient outcomes. Studies already completed demonstrate that rosuvastatin provides greater reductions in low-density lipoprotein cholesterol (LDL-C) than other statins, enabling more patients to achieve LDL-C treatment goals. Additionally, rosuvastatin provides beneficial effects on other components of the atherogenic lipid profile. Ongoing studies will evaluate whether these effects translate into beneficial effects on atherosclerosis and significant reductions in cardiovascular events. Important information will also be provided on the role of statins in less well studied groups, including patients with heart failure, end stage renal disease, and individuals without elevated LDL-C but at heightened vascular risk as a result of increased systemic inflammation. Ultimately, the GALAXY Programme will provide clinical data that will enable physicians to make more effective statin treatment decisions, which will lead to improved patient care and cardiovascular outcomes.

Investigation of functionally liver selective glucokinase activators for the treatment of type 2 diabetes.

Type 2 diabetes is a polygenic disease which afflicts nearly 200 million people worldwide and is expected to increase to near epidemic levels over the next 10-15 years. Glucokinase (GK) activators are currently under investigation by a number of pharmaceutical companies with only a few reaching early clinical evaluation. A GK activator has the promise of potentially affecting both the beta-cells of the pancreas, by improving glucose sensitive insulin secretion, as well as the liver, by reducing uncontrolled glucose output and restoring post-prandial glucose uptake and storage as glycogen. Herein, we report our efforts on a sulfonamide chemotype with the aim to generate liver selective GK activators which culminated in the discovery of 3-cyclopentyl-N-(5-methoxy-thiazolo[5,4-b]pyridin-2-yl)-2-[4-(4-methyl-piperazine-1-sulfonyl)-phenyl]-propionamide (17c). This compound activated the GK enzyme (alphaK(a) = 39 nM) in vitro at low nanomolar concentrations and significantly reduced glucose levels during an oral glucose tolerance test in normal mice.

Tesaglitazar, a dual peroxisome proliferator-activated receptor alpha/gamma agonist, improves apolipoprotein levels in non-diabetic subjects with insulin resistance.

AIM: To determine the effects of the peroxisome proliferator-activated receptor (PPAR) alpha/gamma agonist tesaglitazar on serum levels of apolipoprotein (apo) A-I, apoB, and apoCIII in non-diabetic insulin-resistant subjects. METHODS: This randomized, double-blind, multicentre, placebo-controlled trial examined the effect of tesaglitazar (0.1, 0.25, 0.5, and 1mg) once daily for 12 weeks on apolipoprotein levels in 390 abdominally obese subjects with hypertriglyceridaemia. RESULTS: Tesaglitazar dose-dependently increased serum concentrations of apoA-I (p<0.009) and decreased concentrations of apoB (p<0.0001), the apoB/apoA-I ratio (p<0.0001), and apoCIII (p<0.0001). Similar improvements were observed in all subgroups of subjects, where individuals were grouped according to age, gender, baseline body mass index, serum triglycerides and high-density lipoprotein cholesterol levels. Low-density lipoprotein particle concentrations were also dose-dependently reduced by tesaglitazar (p<0.0001). CONCLUSION: Although tesaglitazar is no longer in clinical development, these data indicate that dual PPARalpha/gamma agonism may be a useful pharmacological approach to improve the atherogenic dyslipidaemia associated with insulin resistance.