Nutritional energy stimulates NAD+ production to promote tankyrase-mediated PARsylation in insulinoma cells.

The poly-ADP-ribosylation (PARsylation) activity of tankyrase (TNKS) regulates diverse physiological processes including energy metabolism and wnt/ß-catenin signaling. This TNKS activity uses NAD+ as a co-substrate to post-translationally modify various acceptor proteins including TNKS itself. PARsylation by TNKS often tags the acceptors for ubiquitination and proteasomal degradation. Whether this TNKS activity is regulated by physiological changes in NAD+ levels or, more broadly, in cellular energy charge has not been investigated. Because the NAD+ biosynthetic enzyme nicotinamide phosphoribosyltransferase (NAMPT) in vitro is robustly potentiated by ATP, we hypothesized that nutritional energy might stimulate cellular NAMPT to produce NAD+ and thereby augment TNKS catalysis. Using insulin-secreting cells as a model, we showed that glucose indeed stimulates the autoPARsylation of TNKS and consequently its turnover by the ubiquitin-proteasomal system. This glucose effect on TNKS is mediated primarily by NAD+ since it is mirrored by the NAD+ precursor nicotinamide mononucleotide (NMN), and is blunted by the NAMPT inhibitor FK866. The TNKS-destabilizing effect of glucose is shared by other metabolic fuels including pyruvate and amino acids. NAD+ flux analysis showed that glucose and nutrients, by increasing ATP, stimulate NAMPT-mediated NAD+ production to expand NAD+ stores. Collectively our data uncover a metabolic pathway whereby nutritional energy augments NAD+ production to drive the PARsylating activity of TNKS, leading to autoPARsylation-dependent degradation of the TNKS protein. The modulation of TNKS catalytic activity and protein abundance by cellular energy charge could potentially impose a nutritional control on the many processes that TNKS regulates through PARsylation. More broadly, the stimulation of NAD+ production by ATP suggests that nutritional energy may enhance the functions of other NAD+-driven enzymes including sirtuins.

Systemic inflammation, intestine, and paraoxonase-1.

Serum paraoxonase 1 (PON1) has been shown to act as an important guardian against cellular damage from oxidized lipids in low-density lipoprotein (LDL), plasma membrane, against toxic agents such as pesticide residues including organophosphates and against bacterial endotoxin. PON1 associated with circulating high-density lipoprotein (HDL) has the ability to prevent the generation of pro inflammatory oxidized phospholipids by reactive oxygen species. The activities of the HDL-associated PON1 and several other anti-inflammatory factors in HDL are in turn negatively regulated by these oxidized lipids. In rabbits, mice, and humans there appears to be an increase in the formation of these oxidized lipids during the acute phase response. This results in the association of acute phase proteins with HDL and inhibition of the HDL-associated PON1 that renders HDL pro inflammatory.In populations, low serum HDL-cholesterol is a risk factor for atherosclerosis and efforts are directed toward therapies to improve the quality and the relative concentrations of LDL and HDL. Apolipoprotein A-I (apoA-I) has been shown to reduce atherosclerotic lesions in laboratory animals. ApoA-I, however, is a large protein that is costly and needs to be administered parenterally. Our group has developed apoA-I mimetic peptides that are much smaller than apoA-I (18 amino acids long vs 243 in ApoA-I itself). These HDL mimetic peptides are much more effective in removing the oxidized phospholipids and other oxidized lipids. They improve LDL and HDL composition and function and reduce lesion formation in animal models of atherogenesis. Following is a brief description of some of the HDL mimetic peptides that can improve HDL and the effect of the peptide on PON1 activity.

Suppression of memory acquisition following co-administration of lithium and atorvastatin through nitric oxide pathway in mice.

PURPOSE: The aim of this study was to investigate the interactive effect of lithium and atorvastatin on cognitive performance and the role of NO as a potential mechanism involved in this interaction. MATERIALS AND METHODS: Memory performance was evaluated in a two-trial recognition Y-maze test and a step-through passive avoidance task in mice. Lithium (5, 10, 20 or 40 mg/kg, i.p.) and atorvastatin (1 mg/kg, p.o.) were administered 1 h before each trial, L-NAME, a non-specific NO synthase inhibitor (3, 10 mg/kg, i.p.); aminoguanidine, a specific inducible NO synthase (iNOS) inhibitor (100 mg/kg); and L-arginine, a NO precursor (750 mg/kg) were administered 30 min before training sessions. The level of plasma NO end-products (NOx) was determined using Griess reagent protocol. RESULTS: 1) Lithium (40 mg/kg) impaired the acquisition of spatial recognition memory; 2) lithium did not affect the retrieval phase of spatial memory; 3) atorvastatin (1 mg/kg) significantly impaired the memory performance, when co-administered with the sub-effective dose of lithium (10 mg/kg), but did not affect the status when administered with lithium (5 mg/kg); 4) L-NAME (10 mg/kg) and aminoguanidine (100 mg/kg) dramatically decreased memory performance in mice received sub-effective doses of both lithium (5 mg/kg) and atorvastatin (1 mg/kg); 5) L-arginine (750 mg/kg) improved the memory acquisition in mice administered lithium (10 mg/kg) and atorvastatin (1 mg/kg); 6) lithium did not affect the cognitive performance in the passive avoidance test. All results were compatible and confirmed with in vitro determination of plasma NOx levels. CONCLUSIONS: Lithium, dose dependently, impaired acquisition phase of spatial recognition memory. Lithium and atorvastatin co-administration impaired spatial recognition memory mediating by nitrergic pathway. In addition to L-arginine, our data from L-NAME and aminoguanidine also support the involvement of NO pathway in this interaction.

Inflammation, high density lipoprotein and endothelium.

High density lipoprotein (HDL) has two important roles: a) it modulates inflammation, and, b) it promotes reverse cholesterol transport. HDL-cholesterol levels are inversely correlated with the risk of cardiovascular events. The main component of HDL, apolipoprotein A-I (apo A-I), is largely responsible for reverse cholesterol transport through the macrophage ATP-binding cassette transporter ABCA1. Apo A-I can be damaged by oxidative mechanisms, which render the protein less able to promote cholesterol efflux. HDL also contains a number of other proteins that are affected by the oxidative environment of the acute-phase response. Modification of the protein components of HDL can convert it from an anti-inflammatory to a pro inflammatory and dysfunctional particle. Small peptides that mimic some of the properties of apo A-I have been shown in preclinical models to improve HDL function and reduce atherosclerosis without altering HDL-cholesterol levels. Endothelium is the interface between the blood and the extra vascular environment regulating the traffic of vital molecules between the blood and tissues. Oxidative stress and excess levels of reactive oxygen species disrupt the normal function of endothelium. HDL and other antioxidant/anti-inflammatory systems prevent endothelial dysfunction and maintain the critical balance needed for normal vascular function.

Validation of the Vancouver Chest Pain Rule: a prospective cohort study.

OBJECTIVES: The objective was to validate the Vancouver Chest Pain Rule in an emergency department (ED) setting to identify very-low-risk patients with acute chest pain. METHODS: A prospective cohort study was conducted on consecutive patients 25 years of age and older presenting to the ED with a chief complaint of acute chest pain during January 2009 to July 2009. According to the Vancouver Chest Pain Rule, cardiac history, chest pain characteristics, physical and electrocardiogram (ECG) findings, and cardiac biomarker measurement (creatine kinase-myocardial band isoenzyme [CK-MB]) were used to identify patients with very low risk for developing acute coronary syndrome (ACS) in 30 days. The primary outcome was defined as developing ACS (myocardial infarction or non-ST-elevation myocardial infarction [MI]/unstable angina) within 30 days of ED presentation, and all diagnoses were made using predefined explicit criteria. Sensitivity, specificity, positive predictive value, and negative predictive value were calculated. RESULTS: Of 593 patients who were eligible for evaluation, 39 (6.6%) developed MI and 43 (7.3%) developed unstable angina. Among all patients, 292 (49.2%) patients could have been assigned to the very-low-risk group and discharged after a brief ED assessment according to the Vancouver Chest Pain Rule. Among these patients, four (1.4%) developed ACS within 30 days. Sensitivity of the rule was 95.1% (95% confidence interval [CI]=88.0% to 98.7%), specificity was 56.3% (95% CI=52.0% to 60.7%), positive prediction value was 25.9% (95% CI=21.0% to 31.0%), and negative prediction value was 98.6% (95% CI=96.5% to 99.6%). CONCLUSIONS: This study showed a lower sensitivity and higher specificity when applying the Vancouver Chest Pain Rule to this population as compared to the original study.

Comparison of topical anesthetic cream (EMLA) and diclofenac suppository for pain relief after hemorrhoidectomy: a randomized clinical trial.

PURPOSE: We compared the efficacy and side effects of diclofenac and a topical eutectic mixture of local anesthetics (EMLA) for pain relief after hemorrhoidectomy. METHODS: Ninety patients, nominated for elective hemorrhoidectomy, were recruited for this randomized clinical trial and were randomly categorized into three groups (30 patients in each group). After surgery, the patients in the first group received one 100 mg diclofenac suppository, those in the second group received 5 g of EMLA, and those in the third group received 5 g of petrolatum ointment (control group). The pain intensity was measured using a visual analog scale (VAS). Twenty-five mg of intramuscular pethidine was administered upon the patient's request. Pain measurements were performed on the patient's transfer to the recovery ward, 2 h after surgery, the evening and the morning after surgery. RESULTS: The EMLA group yielded the lowest VAS score on transfer to recovery and at 2 h after surgery (p < 0.05). The diclofenac group reported the lowest VAS score in the evening and the morning after surgery (p < 0.05). CONCLUSIONS: Topical use of an EMLA cream is appropriate for short-term pain control following hemorrhoidectomy, while diclofenac yields a more sustainable pain control.