Refeeding with conjugated linoleic acid increases serum cholesterol and modifies the fatty acid profile after 48 hours of fasting in rats / Realimentación con ácido linoleico conjugado aumenta colesterol sérico y altera el perfil de ácidos grasos después de 48 horas de ayuno en ratas

There is no consensus about the effects of conjugated linoleic acid (CLA) on lipid metabolism, especially in animals fed a high-fat diet. Therefore, the objective of the present study was to evaluate the incorporation of CLA isomers into serum, liver and adipose tissue, as well as the oxidative stress generated in rats refed with high-fat diets after a 48 hour fast. Rats were refed with diets containing soybean oil, rich in linoleic acid [7% (Control Group - C) or 20% (LA Group)], CLA [CLA Group - 20% CLA mixture (39.32 mole% c9,t11-CLA and 40.59 mole% t10,c12- CLA)], soybean oil + CLA (LA+CLA Group - 15.4% soybean oil and 4.6% CLA) or animal fat (AF, 20% lard). The CLA group showed lower weight gain and liver weight after refeeding, as well as increased serum cholesterol. The high dietary fat intake induced fat accumulation and an increase in α-tocopherol in the liver, which were not observed in the CLA group. Circulating α-tocopherol was increased in the CLA and CLA+LA groups. The high-fat diets reduced liver catalase activity. CLA isomers were incorporated into serum and tissues. In this short term refeeding experimental model, CLA prevented hepatic fat accumulation, although it produced an increase in serum cholesterol (AU)

No hay consenso acerca de los efectos del ácido linoleico conjugado (CLA) sobre el metabolismo lipídico, especialmente en animales alimentados con una dieta alta en grasa. Por lo tanto, el objetivo del presente estudio fue evaluar la incorporación de isómeros de CLA en el suero, hígado y tejido adiposo, así como el estrés oxidativo generado en ratas realimentadas con dietas altas en grasa después de 48 horas de ayuno. Los animales fueron realimentados con dietas que contenían aceite de soja, rico en ácido linoleico [7% (Groupo Control - C)], o 20% (Groupo LA)], CLA [Groupo CLA - 20% de mezclade CLA (39,32% moles del c9,t11-CLA y 40.59% moles del t10,c12-CLA)], aceite de soja + CLA (Grupo LA+- CLA - 15.4 % de aceite de soja y 4,6% de CLA) o grasa animal (Grupo AF, 20% de manteca de cerdo). El grupo CLA tuvo menor aumento de peso y menor peso hepático después de la realimentación, así como aumento del colesterol total em el suero. La dieta alta en grasa indujo la acumulación de grasa y un aumento de α-tocoferol en el hígado, que no se observaron en el grupo CLA. El α-tocoferol sérico fue mayor en los grupos CLA y LA+CLA. Las dietas altas en grasa redujeron la actividad de la catalasa hepática. Isómeros de CLA fueron incorporados em el suero y tejidos. En este modelo de realimentación de corto plazo, el CLA ha impedido la acumulación de grasa hepática, aunque genero un aumento del colesterol total sérico (AU)

Local gene transduction of cyclooxygenase-1 increases blood flow in injured atherosclerotic rabbit arteries.

BACKGROUND: Cyclooxygenase-1 (COX-1) is the rate-limiting component in the synthesis of prostacyclin (PGI2), an important vasodilator and antithrombotic molecule. In balloon-injured, atherosclerosis-free porcine arteries, COX-1 gene transduction increases PGI2 production, induces durable vasodilation, and reduces thrombus formation. We tested the effectiveness of COX-1 local gene transduction for the prevention of postangioplasty restenosis in atherosclerotic arteries in a hypercholesterolemic rabbit model. METHODS AND RESULTS: We injured 1 carotid artery in 43 Watanabe heritable hyperlipidemic rabbits and performed local gene transduction using a viral vector containing the COX-1 gene (AdCOX-1, n=22) or no genes (Adnull, n=21). Three days later, AdCOX-1-treated arteries stimulated with arachidonic acid produced 100% more PGI2 (P<0.01), 400% more prostaglandin E2 (PGE2) (P<0.01), 400% more prostaglandin E1 (PGE1) (P<0.01), and 250% more cAMP (P<0.05) than Adnull-treated arteries. Twenty-eight days after treatment, Doppler sonography showed that blood flow velocity was preserved in AdCOX-1-treated arteries (ratio 0.92, injured compared with contralateral uninjured carotid artery) but reduced in Adnull-treated arteries (ratio 0.39), suggesting that AdCOX-1 prevented restenosis after injury. COX-1-transduced arteries also showed 80% greater lumen area 28 days after injury (P<0.01). CONCLUSIONS: The effectiveness of COX-1 in preventing restenosis and preserving normal blood flow 28 days after injury results from increased lumen area caused by durable vasodilation. COX-1 efficacy correlates with an early increase in the production of PGI2, PGE2, PGE1 (known to cause vasodilation), and cAMP. These results demonstrate for the first time that COX-1 gene transduction is an effective treatment for the prevention of postangioplasty restenosis of atherosclerotic arteries under clinically relevant conditions.

The risk for myocardial infarction with cyclooxygenase-2 inhibitors: a population study of elderly adults.

BACKGROUND: Cyclooxygenase-2 (COX-2) selective inhibitors have been marketed since 1999 as safer alternatives to nonsteroidal anti-inflammatory drugs (NSAIDs). Debate about their cardiac safety has culminated in the recent withdrawal of rofecoxib. Additional studies are needed to better understand this risk and to determine whether this safety concern represents a class effect. OBJECTIVE: To assess the influence of various NSAIDs on the risk for a first myocardial infarction (MI). DESIGN: Population-based, retrospective cohort study analyzed using a time-matched, nested case-control approach. SETTING: Quebec, Canada. PARTICIPANTS: 113,927 elderly persons without previous MI and newly treated with an NSAID between 1 January 1999 and 30 June 2002. MEASUREMENTS: NSAID exposure and occurrence of MI assessed by using Quebec's administrative health databases. RESULTS: Compared with no use of NSAIDs in the year preceding the event, current use of rofecoxib was associated with an increased risk for an acute MI (rate ratio [RR], 1.24 [95% CI, 1.05 to 1.46]) that was more pronounced at higher doses (RR, 1.73 [CI, 1.09 to 2.76]). The concomitant use of aspirin appears to decrease the risk associated with low-dose rofecoxib (RR, 1.00 [CI, 0.77 to 1.28]) but not with high-dose rofecoxib (RR, 2.36 [CI, 1.27 to 4.39]). No increased risks were observed with celecoxib (RR, 0.99 [CI, 0.85 to 1.16]) or the other NSAIDs. LIMITATIONS: The study could not completely account for all potential confounders, including over-the-counter use of aspirin and ibuprofen. CONCLUSIONS: These results provide evidence of an increased risk for acute MI in current users of rofecoxib among elderly persons with no history of MI. This risk appears greater at higher doses. Aspirin use mitigates the risk associated with low-dose but not high-dose rofecoxib. There was no evidence of an increased risk with the other NSAIDs.

Tramadol/acetaminophen combination tablets for the treatment of pain associated with osteoarthritis flare in an elderly patient population.

OBJECTIVES: To evaluate the efficacy and safety of adding tramadol 37.5 mg/acetaminophen (APAP) 325 mg combination tablets (tramadol/APAP) to existing therapy for painful osteoarthritis (OA) flare in a subset of elderly patients. DESIGN: Randomized, double-blind, placebo-controlled, 10-day add-on study. SETTING: Thirty outpatient centers. PARTICIPANTS: Of 308 patients with painful OA flare, a subset of 113 patients aged 65 and older. MEASUREMENTS: Average daily pain intensity and pain relief scores for Days 1 through 5 and secondary quality-of-life measures and medication assessments. METHODS: Patients received one or two tramadol/APAP tablets or placebo four times per day for 10 days during ongoing nonselective or cyclooxygenase (COX)-2-selective nonsteroidal antiinflammatory drug (NSAID) therapy. RESULTS: Tramadol/APAP (n=69) was significantly superior to placebo (n=44) for average daily pain intensity (P=.034) and pain relief (P=.010) for Days 1 through 5 and Days 1 through 10 (P=.012 and P=.019, respectively). Tramadol/APAP had significantly better investigator (P<.001) and patient (P=.001) overall medication assessments and significantly better scores on three of four Western Ontario and McMaster Universities Osteoarthritis Index measures (P< or =.027). Most common adverse events with tramadol/APAP were nausea (18.8%), vomiting (13.0%), dizziness (11.6%), and constipation (4.3%), with an incidence similar to that of the overall study population. Mean daily dose of tramadol/APAP was 4.5 tablets (168 mg/1,458 mg). CONCLUSION: Tramadol/APAP add-on therapy effectively managed painful OA flare in this elderly subset and was generally well tolerated.

Influence of cyclooxygenase inhibitors on the central histaminergic stimulations of hypothalamic - pituitary - adrenal axis.

Brain histamine participates in central regulation of the hypothalamic-pituitary-adrenal (HPA) axis. Endogenous prostaglandins modulate signal transduction of different neurotransmitters involved in activation of HPA axis. In the present experiment we investigated whether endogenous prostaglandins are involved in the stimulation of ACTH and corticosterone secretion by histaminergic systems in the rat brain. Histamine (50 microg), histamine-trifluoromethyl-toluidine derivative (HTMT, 75microg) a selective and potent H(1)-receptor agonist, and amthamine (50 microg) a H(2)-receptor agonist given intracerebroventricularly (i.c.v.) to non-anesthetized rats considerably increased ACTH and corticosterone secretion 1h after administration. A non-selective cyclooxygenase inhibitor indomethacin (2 mg/kg i.p. or 10 microg i.c.v.), piroxicam (0.02 and 0.2 microg i.c.v.) a more potent antagonist of constitutive cyclooxygenase (COX-1) and compound NS-398 (0.1 and 1.0 microg i.c.v.), a selective inhibitor of inducible cyclooxygenase (COX-2) were given 15 min before histamine and histamine receptor agonists. One hour after the last injection trunk blood from decapitated rats was collected for hormones determination. The histamine-induced ACTH and corticosterone secretion was significantly diminished by piroxicam and was not markedly altered by indomethacin and compound NS-398. The HTMT-elicited increase in ACTH and corticosterone secretion was significantly prevented by indomethacin and was not affected by piroxicam or compound NS-398. The amthamine-evoked increase in ACTH and corticosterone secretion was not markedly influenced by any cyclooxygenase blocker applied in the present experiment. These results indicate that the histamine H(1)-receptor transmitted central stimulation of the HPA axis is considerably mediated by prostaglandins generated by consititutive cyclooxygenase, whereas stimulation transmitted via H(2)-receptor does not significantly depend on endogenous prostaglandins mediation.

Efectos mecánicos y dinámicos de la hipertensión sobre el endotelio / Mechanical and dynamical effects of hypertension on endothelia

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