Application of NHG guidelines in patients referred for stable chest pain syndromes.

UNLABELLED: Purpose. Guidelines of the Dutch Association of General Practitioners (NHG) dictate the evaluation, treatment, and referral process of patients with stable chest pain syndromes (CPS). Adherence to this guideline was assessed in a consecutive group of patients referred to our hospital. Methods. We retrospectively studied the records of 296 subjects referred to our outpatient department in 2007 for evaluation of stable CPS. Referral letters were checked for completeness (past and present history, mentioning of risk factors for cardiovascular disease, physical examination, listing of medication) and used to judge adherence to the guideline. In a subset of patients, additional information regarding the referral process was gathered by telephone interview.Results. The referral letter was complete in only 67 patients (23%); items most often not reported were physical examination (63%) and cardiovascular risk factors (62%). Judging from the referral letter, 23 patients (8%) were evaluated in accordance with the NHG guideline prior to their referral. In patients in whom the final diagnosis of angina pectoris was made by the cardiologist, this was 20%. Seventy-nine patients were contacted by telephone after their work-up by the cardiologist; 36 of them (44%) reported being referred at their first visit to their primary physician, while 14 (18%) were referred at their own request. CONCLUSION: Prior to referral, only a minority of patients with stable CPS were evaluated and treated in accordance with NHG guidelines. Furthermore, their referral letter was often incomplete. (Neth Heart J 2010;18:178-82.).

Dietary diversity scores can be improved through the use of portion requirements: an analysis in young Filipino children.

OBJECTIVES: Early childhood malnutrition is a pressing international concern which dietary diversity scores (summary scores of food groups in the diet) may be helpful in addressing. We explored three current research needs surrounding diversity scores: the impact of portion size on score function, the relationship of scores to nutrient adequacy and density and the ability of scores to function as screening tools. SUBJECTS/METHODS: 1810 children, age 24 months. Cross sectional study of a birth cohort. RESULTS: We evaluated two nine food group dietary diversity scores based on 0 and 10 g minimum food group requirements for their relationship to nutrient adequacy and nutrient density. Both scores were significantly correlated with nutrient adequacy and density and predicted statistically significant increases (P<0.05) in the probability of adequacy for all nutrients. However, correlations and predicted increases were somewhat larger for the 10 g score. We also considered the sensitivity and specificity of each score for detecting low and high nutrient adequacy in the population. The 10 g cutoff improved score ability to predict low nutrient adequacy, and reduced the misclassification of subjects for all comparisons. CONCLUSIONS: This research suggests that the score without portion requirements reflects dietary adequacy, but when feasible, further refinement of diversity scores is desirable through the application of minimum portion requirements.

A modest glucokinase overexpression in the liver promotes fed expression levels of glycolytic and lipogenic enzyme genes in the fasted state without altering SREBP-1c expression.

Hepatic genes crucial for carbohydrate and lipid homeostasis are regulated by insulin and glucose metabolism. However, the relative contributions of insulin and glucose to the regulation of metabolic gene expression are poorly defined in vivo. To address this issue, adenovirus-mediated hepatic overexpression of glucokinase was used to determine the effects of increased hepatic glucose metabolism on gene expression in fasted or ad libitum fed rats. In the fasted state, a 3 fold glucokinase overexpression was sufficient to mimic feeding-induced increases in pyruvate kinase and acetyl CoA carboxylase mRNA levels, demonstrating a primary role for glucose metabolism in the regulation of these genes in vivo. Conversely, glucokinase overexpression was unable to mimic feeding-induced alterations of fatty acid synthase, glucose-6-phosphate dehydrogenase, carnitine palmitoyl transferase I or PEPCK mRNAs, indicating insulin as the primary regulator of these genes. Interestingly, glucose-6-phosphatase mRNA was increased by glucokinase overexpression in both the fasted and fed states, providing evidence, under these conditions, for the dominance of glucose over insulin signaling for this gene in vivo. Importantly, glucokinase overexpression did not alter sterol regulatory element binding protein 1-c mRNA levels in vivo and glucose signaling did not alter the expression of this gene in primary hepatocytes. We conclude that a modest hepatic overexpression of glucokinase is sufficient to alter expression of metabolic genes without changing the expression of SREBP-1c.

Losartan prevents contractile dysfunction in rat myocardium after left ventricular myocardial infarction.

We studied the effects of chronic losartan (Los) treatment on contractile function of isolated right ventricular (RV) trabeculae from rat hearts 12 wk after left ventricular (LV) myocardial infarction (MI) had been induced by ligation of the left anterior descending artery at 4 wk of age. After recovery, one-half of the animals were started on Los treatment (MI+Los; 30 mg x kg(-1) x day(-1) per os); the remaining animals were not treated (MI group). Rats without infarction or Los treatment served as controls (Con group). MI resulted in increases in LV and RV weight and unstressed LV cavity diameter; these were partially prevented by Los treatment. The active peak twitch force-sarcomere length relation was depressed in MI compared with either Con or MI+Los. Likewise, maximum Ca2+ saturated twitch force was depressed in MI, whereas twitch relaxation and twitch duration were prolonged. Myofilament function, as measured in skinned trabeculae, was not significantly different among the Con, MI, and MI+Los groups. We conclude that Los prevents contractile dysfunction in rat RV trabeculae after LV MI. Our results suggest that the beneficiary effect of Los treatment results not from improved myofilament function but rather from improved myocyte Ca2+ homeostasis.

Overexpression of glutamine: fructose-6-phosphate amidotransferase in the liver of transgenic mice results in enhanced glycogen storage, hyperlipidemia, obesity, and impaired glucose tolerance.

To examine the effect of increased hexosamine flux in liver, the rate-limiting enzyme in hexosamine biosynthesis (glutamine:fructose-6-phosphate amidotransferase [GFA]) was overexpressed in transgenic mice using the PEPCK promoter. Liver from random-fed transgenic mice had 1.6-fold higher GFA activity compared with nontransgenic control littermates (276 +/- 24 pmol x mg(-1) x min(-1) in transgenic mice vs. 176 +/- 18 pmol x mg(-1) x min(-1) in controls, P < 0.05) and higher levels of the hexosamine end product UDP-N-acetyl glucosamine (288 +/- 11 pmol/g in transgenic mice vs. 233 +/- 10 pmol/g in controls, P < 0.001). Younger transgenic mice compared with control mice had lower fasting serum glucose (4.8 +/- 0.5 mmol/l in transgenic mice vs. 6.5 +/- 0.8 mmol/l in controls, P < 0.05) without higher insulin levels (48.0 +/- 7.8 pmol/l in transgenic mice vs. 56.4 +/- 5.4 pmol/l in controls, P = NS); insulin levels were significantly lower in transgenic males (P < 0.05). At 6 months of age, transgenic animals had normal insulin sensitivity by the hyperinsulinemic clamp technique. Hepatic glycogen content was higher in the transgenic mice (108.6 +/- 5.2 pmol/g in transgenic mice vs. 32.8 +/- 1.3 micromol/g in controls, P < 0.01), associated with an inappropriate activation of glycogen synthase. Serum levels of free fatty acids (FFAs) and triglycerides were also elevated (FFAs, 0.67 +/- 0.03 mmol/l in transgenic mice vs. 0.14 +/- 0.01 in controls; triglycerides, 1.34 +/- 0.15 mmol/l in transgenic mice vs. 0.38 +/- 0.01 in controls, P < 0.01). Older transgenic mice became heavier than control mice and exhibited relative glucose intolerance and insulin resistance. The glucose disposal rate at 8 months of age was 154 +/- 5 mg x kg(-1) x min(-1) in transgenic mice vs. 191 +/- 6 mg x kg(-1) x min(-1) in controls (P < 0.05). We conclude that hexosamines are mediators of glucose sensing for the regulation of hepatic glycogen and lipid metabolism. Increased hexosamine flux in the liver signals a shift toward fuel storage, resulting ultimately in obesity and insulin resistance.

NF-kappa B inhibits glucocorticoid and cAMP-mediated expression of the phosphoenolpyruvate carboxykinase gene.

Transcription of the phosphoenolpyruvate carboxykinase (PEPCK) gene is regulated by a variety of agents. Glucocorticoids, retinoic acid, and glucagon (via its second messenger, cAMP) stimulate PEPCK gene transcription, whereas insulin, phorbol esters, cytokines, and oxidative stress have an opposing effect. Stimulation of PEPCK gene expression has been extensively studied, and a number of important DNA elements and binding proteins that regulate the transcription of this gene have been identified. However, the mechanisms utilized to turn off expression of this gene are not well-defined. Many of the negative regulators of PEPCK gene transcription also stimulate the nuclear localization and activation of the transcription factor NF-kappaB, so we hypothesized that this factor could be involved in the repression of PEPCK gene expression. We find that the p65 subunit of NF-kappaB represses the increase of PEPCK gene transcription mediated by glucocorticoids and cAMP in a concentration-dependent manner. The mutation of an NF-kappaB binding element identified in the PEPCK gene promoter fails to abrogate this repression. Further analysis suggests that p65 represses PEPCK gene transcription through a protein.protein interaction with the coactivator, CREB binding protein.

Effects of glucosamine infusion on insulin secretion and insulin action in humans.

Glucose toxicity (i.e., glucose-induced reduction in insulin secretion and action) may be mediated by an increased flux through the hexosamine-phosphate pathway. Glucosamine (GlcN) is widely used to accelerate the hexosamine pathway flux, independently of glucose. We tested the hypothesis that GlcN can affect insulin secretion and/or action in humans. In 10 healthy subjects, we sequentially performed an intravenous glucose (plus [2-3H]glucose) tolerance test (IVGTT) and a euglycemic insulin clamp during either a saline infusion or a low (1.6 micromol x min(-1) x kg(-1)) or high (5 micromol x min(-1) x kg(-1) [n = 5]) GlcN infusion. Beta-cell secretion, insulin (SI*-IVGTT), and glucose (SG*) action on glucose utilization during the IVGTT were measured according to minimal models of insulin secretion and action. Infusion of GlcN did not affect readily releasable insulin levels, glucose-stimulated insulin secretion (GSIS), or the time constant of secretion, but it increased both the glucose threshold of GSIS (delta approximately 0.5-0.8 mmol/l, P < 0.03-0.01) and plasma fasting glucose levels (delta approximately 0.3-0.5 mmol/l, P < 0.05-0.02). GlcN did not change glucose utilization or intracellular metabolism (glucose oxidation and glucose storage were measured by indirect calorimetry) during the clamp. However, high levels of GlcN caused a decrease in SI*-IVGTT (delta approximately 30%, P < 0.02) and in SG* (delta approximately 40%, P < 0.05). Thus, in humans, acute GlcN infusion recapitulates some metabolic features of human diabetes. It remains to be determined whether acceleration of the hexosamine pathway can cause insulin resistance at euglycemia in humans.

Transcriptional regulation of transforming growth factor beta1 by glucose: investigation into the role of the hexosamine biosynthesis pathway.

BACKGROUND: The hexosamine biosynthesis pathway (HBP) is hypothesized to mediate many of the adverse effects of hyperglycemia. We have shown previously that increased flux through this pathway leads to induction of the growth factor transforming growth factor-alpha (TGF-alpha) and to insulin resistance in cultured cells and transgenic mice. TGF-beta is regulated by glucose and is involved in the development of diabetic nephropathy. We therefore hypothesized that the HBP was involved in the regulation of TGF-beta by glucose in rat vascular and kidney cells. METHODS: A plasmid containing the promoter region of TGF-beta1 cloned upstream of the firefly luciferase gene was electroporated into rat aortic smooth muscle, mesangial, and proximal tubule cells. Luciferase activity was measured in cellular extracts from cells cultured in varying concentrations of glucose and glucosamine. RESULTS: Glucose treatment of all cultured cells led to a time- and dose-dependent stimulation in TGF-beta1 transcriptional activity, with high (20 mM) glucose causing a 1.4- to 2.0-fold increase. Glucose stimulation did not occur until after 12 hours and disappeared after 72 hours of treatment. Glucosamine was more potent than glucose, with 3 mM stimulating up to a 4-fold increase in TGFbeta1-transcriptional activity. The stimulatory effect of glucosamine was also dose-dependent but was slower to develop and longer lasting than that of glucose. CONCLUSIONS: The metabolism of glucose through the HBP mediates extracellular matrix production, possibly via the stimulation of TGF-beta in kidney cells. Hexosamine metabolism therefore, may play a role in the development of diabetic nephropathy.

Insulin stimulation of glutamine: fructose-6-phosphate amidotransferase occurs via an insulin-like growth factor-1 pathway in rat fibroblasts.

The biosynthetic pathway for hexosamine mediates some of the adverse effects of high glucose. The rate limiting enzyme in this pathway is glutamine:fructose-6-phosphate amidotransferase (GFA). Using HPLC, the regulation of GFA activity by glucose and insulin was studied in wild type and rat-1 fibroblasts overexpressing human insulin receptors (HIRcB cells). In wild type cells only maximal doses of insulin (580 ng/ml) resulted in an increase in GFA activity (51.0 +/- 40.6%). In HIRcB cells insulin led to a dose dependent increase in GFA activity that was enhanced when compared to wild type (89 +/- 5% (p<0.001) increase at 580 ng/ml). Insulin's action was glucose dependent and required prolonged serum deprivation. HIRcB's cultured in 0 mM glucose had a 58.2% (p<0.001) decrease in insulin stimulation. However, when present the concentration of glucose (2-20 mM) did not affect insulin stimulation of GFA activity. Most of insulin's effects occur by way of the IGF-1 receptor as a two-fold stimulation of GFA activity was seen with significantly lower doses (10 ng/ml) of IGF-1. We conclude that GFA enzyme activity is upregulated by insulin and this may occur via a IGF-1 receptor mediated pathway.

Combination of calcium channel blockers and beta-blockers for patients with exercise-induced angina pectoris: beneficial effect of calcium channel blockers largely determined by their effect on heart rate.

The combination of calcium channel blockers and beta-blockers is more effective for the treatment of exercise-induced angina pectoris than beta-blocker monotherapy. As ischemia in exercise-induced angina is essentially preceded by an increase in heart rate, calcium channel blockers with a negative chronotropic property may perform better for this purpose than nonchronotropic compounds. A 335-patient, 10-week, double-blind, parallel-group comparison of amlodipine 5 mg and 10 mg, diltiazem 200 mg and 300 mg, and mibefradil 50 mg and 100 mg treatment added to baseline beta-blocker treatment was performed. Exercise testing (ETT) was performed by bicycle ergometry. All of the calcium channels blockers significantly delayed the onset of 1 mm ST-segment depression on ETT (p < 0.001 for any treatment vs. baseline). In addition, mibefradil, in both low- and high-dose treatments, produced the largest delays (low dose: different from diltiazem and amlodipine by 24.1 and 29.8 seconds, respectively, p < 0.003 and < 0.001; high dose: different from diltiazem and amlodipine by 33.7 and 37.0 seconds, respectively, p < 0.001 and < 0.001). A stepwise logistic regression analysis revealed that this beneficial effect of calcium channel blockers was largely dependent on their effect on heart rate. Serious symptoms of dizziness likewise occurred significantly more frequently on mibefradil (p < 0.05 vs. diltiazem) and urged no fewer than 19 patients on mibefradil to withdraw from the trial. The authors conclude that calcium channel blockers with a negative chronotropic property provide a better delay of ischemia in patients with exercise-induced angina, but the concomitant risk of intolerable dizziness may reduce this benefit.

Combination of calcium channel blockers and beta blockers for patients with exercise-induced angina pectoris: a double-blind parallel-group comparison of different classes of calcium channel blockers. The Netherlands Working Group on Cardiovascular Research (WCN).

The combination of calcium channel blockers and beta blockers is more effective for the treatment of exercise-induced angina pectoris than beta blocker monotherapy. Since ischemia in exercise-induced angina is essentially preceded by an increase in heart rate, calcium channel blockers with negative chronotropic property may perform better for this purpose than nonchronotropic compounds. A 335-patient, 10-week, double-blind, parallel-group comparison of amlodipine 5 and 10 mg, diltiazem XR 200 and 300 mg, and mibefradil 50 and 100 mg treatment added to baseline beta blocker treatment was performed. Exercise testing (ETT) was performed by bicycle ergometry. Although none of the calcium channel blockers improved duration of exercise or amount of workload, all of them significantly delayed onset of 1 mm ST segment depression on ETT (p<0.001 for any treatment versus baseline). In addition, mibefradil, both low- and high-dose treatment, produced the largest delays (low dose: different from diltiazem and amlodipine by 24.1 and 29.8 s, p<0.003 and <0.001, respectively; high dose: different from diltiazem and amlodipine by 33.7 and 37.0 s, p<0.001 and <0.001, respectively). These effects were linearly correlated to the amount of rate pressure product (RPP) reduction. Serious symptoms of dizziness likewise occurred significantly more frequently with mibefradil (p<0.05) and led 19 patients taking mibefradil to withdraw from the trial. The authors conclude that calcium channel blockers with negative chronotropic property provide better delay of ischemia in patients with exercise-induced angina but that the concomitant risk of intolerable dizziness largely reduces this benefit.

Combination of calcium channel blockers and beta-adrenoceptor blockers for patients with exercise-induced angina pectoris: a double-blind parallel-group comparison of different classes of calcium channel blockers. Netherlands Working Group on Cardiovascular Research (WCN).

AIMS: The combination of calcium channel blockers and beta-adrenoceptor blockers is more effective for the treatment of exercise-induced angina pectoris than beta-adrenoceptor blocker monotherapy. As ischaemia in exercise-induced angina is preceded by increase in heart rate, calcium channel blockers with negative chronotropic properties may perform better for this purpose than nonchronotropic compounds. METHODS: A 335 patient double-blind parallel-group study comparing 14 day treatment with amlodipine 5 and 10 mg, with diltiazem 200 and 300 mg, and mibefradil 50 and 100 mg added to baseline beta-adrenoceptor blocker treatment was performed. Exercise testing (ETT) was performed by bicycle ergometry. RESULTS: Although none of the calcium channel blockers improved duration of exercise or amount of workload, all significantly delayed onset of 1 mm ST-segment depression on ETT (P<0.001 for any treatment vs baseline). In addition, mibefradil, both low and high dose treatment, produced the longest delays (low dose: different from diltiazem and amlodipine by 24.1 and 29.8 s, respectively, P<0. 003 and <0.001; high dose: different from diltiazem and amlodipine by 33.7 and 37.0 s, respectively, P<0.001 and <0.001). These effects were linearly correlated with the reduction in rate pressure product (RPP). Serious symptoms of dizziness occurred significantly more frequently on mibefradil (P<0.05), and 19 patients on mibefradil withdrew from trial. CONCLUSIONS: Calcium channel blockers with negative chronotropic properties provide greater delay of ischaemia in patients with exercise-induced angina, but the concomitant risk of intolerable dizziness attenuates this benefit.

Regulation of glutamine:fructose-6-phosphate amidotransferase by cAMP-dependent protein kinase.

Glutamine:fructose-6-phosphate amidotransferase (GFA) is the rate-limiting enzyme in hexosamine biosynthesis, an important pathway for cellular glucose sensing. Human GFA has two potential sites for phosphorylation by cAMP-dependent protein kinase A (PKA). To test whether GFA activity is regulated by cAMP-dependent phosphorylation, rat aortic smooth muscle cells were treated in vivo with cAMP-elevating agents, 10 micromol/l forskolin, 1 mmol/l 8-Br-cAMP, or 3-isobutyl-1-methylxanthine. All treatments resulted in rapid and significant increases (2- to 2.4-fold) in GFA activity assayed in cytosolic extracts. Maximal effects of forskolin were observed at 10 micromol/l and 60 min. Preincubation of cells with cycloheximide did not abolish the effect of forskolin. Incubation of cytosolic extracts at 37 degrees C for 10 min in a buffer without phosphatase inhibitors led to a 79% decrease of GFA activity. This loss of activity was inhibited by the addition of phosphatase inhibitors (5 mmol/l sodium orthovanadate, 50 mmol/l sodium fluoride, or 5 mmol/l EDTA, but not 100 nmol/l okadaic acid), suggesting that GFA undergoes rapid dephosphorylation by endogenous phosphatases. Purified GFA is phosphorylated in vitro by purified PKA, resulting in a 1.7-fold increase in GFA activity. Treatment of GFA with purified protein kinase C had no effect. We conclude that GFA activity may be modulated by cAMP-dependent phosphorylation.

Electrocardiographic identification of abnormal ventricular depolarization and repolarization in patients with idiopathic ventricular fibrillation.

OBJECTIVES: We sought to gain more insight into the arrhythmogenic etiology of idiopathic ventricular fibrillation (VF) by assessing ventricular depolarization and repolarization properties by means of various electrocardiographic (ECG) techniques. BACKGROUND: Idiopathic VF occurs in the absence of demonstrable structural heart disease. Abnormalities in ventricular depolarization or repolarization have been related to increased vulnerability to VF in various cardiac disorders and are possibly also present in patients with idiopathic VF. METHODS: In 17 patients with a first episode of idiopathic VF, 62-lead body surface QRST integral maps, QT dispersion on the 12-lead ECG and XYZ-lead signal-averaged ECGs were computed. RESULTS: All subjects of a healthy control group had a normal dipolar QRST integral map. In patients with idiopathic VF, either a normal dipolar map (29%,), a dipolar map with an abnormally large negative area on the right side of the thorax (24%) or a nondipolar map (47%) were recorded. Only four patients (24%) had increased QT dispersion on the 12-lead ECG and late potentials could be recorded in 6 (38%) of 16 patients. During a median follow-up duration of 56 months (range 9 to 136), a recurrent arrhythmic event occurred in 7 patients (41%), all of whom had an abnormal QRST integral map. Five of these patients had late potentials, and three showed increased QT dispersion on the 12-lead ECG. CONCLUSIONS: In patients with idiopathic VF, ventricular areas of slow conduction, regionally delayed repolarization or dispersion in repolarization can be identified. Therefore, various electrophysiologic conditions, alone or in combination, may be responsible for the occurrence of idiopathic VF. Body surface QRST integral mapping may be a promising method to identify those patients who do not show a recurrent episode of VF.

Insulin and glucosamine infusions increase O-linked N-acetyl-glucosamine in skeletal muscle proteins in vivo.

O-linked N-acetylglucosamine (O-GlcNAc) is an abundant posttranslational modification of serine/threonine residues of nuclear and cytoplasmic proteins. We determined whether insulin or coinfusion of glucosamine (GlcN) with insulin alters O-GlcNAc of skeletal muscle proteins. Three groups of conscious fasted rats received 6-hour infusions of either saline (BAS), insulin 18 mU/kg.min and saline (INS), or insulin and GlcN 30 micromol/kg.min (GLCN) during maintenance of normoglycemia. At 6 hours, the concentrations of muscle UDP-GlcNAc, UDP-N-acetylgalactosamine (UDP-GalNAc), UDP-glucose (UDP-Glc), UDP-galactose (UDP-Gal), glycogen, and N and O-linked GlcNAc (galactosyltransferase labeling followed by beta elimination) were measured in freeze-clamped abdominis muscle. Insulin increased whole-body glucose uptake from 49 +/- 5 to 239 +/- 8 micromol/kg.min (P < .001) and glycogen in abdominis muscle from 138 +/- 11 to 370 +/- 26 mmol/kg dry weight (P < .001). Insulin increased the amount of cytosolic N - and O-linked GlcNAc by 56% from 362 +/- 30 to 564 +/- 45 dpm/microg protein . 100 min (P < .02), and O-GlcNAc from 221 +/- 16 to 339 +/- 27 dpm/microg . 100 min (P < .02). Glycogen content was positively correlated with the amount of total (r = .90, P < .005) and O-linked GlcNAc in insulin-infused animals. Coinfusion of GlcN with insulin increased muscle UDP-GlcNAc about fourfold (100 +/- 6 nmol/g) compared with insulin (27 +/- 1, P < .001) or saline (25 +/- 1, P < .001) infusion. GlcN also decreased glucose uptake over 6 hours by 30% to 168 +/- 8 micromol/kg . min (P < .001 for GLCN v INS) and muscle glycogen to 292 +/- 24 mmol/kg dry weight (P < .05 for GLCN v INS). Both total (635 +/- 60 dpm/microg . 100 min, P < .002) and O-linked GlcNAc (375 +/- 36 dpm/microg . 100 min, P < .002) in the cytosol were significantly higher in GLCN rats (635 +/- 60 dpm/microg) versus BAS rats (P < .002). As in INS rats, muscle glycogen and O-GlcNAc were positively correlated in GLCN rats (r = .54, P < .05). Variation in total and O-linked GlcNAc in GLCN rats was due both to GlcN (P < .02) and to variation in the glycogen content (P < .005).