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Biomedical subjects

L Carbonell

Publications and source records attributed to L Carbonell.

12 recordsLinked to original sources
PubMed2006

Pulsed electric fields versus thermal treatment: equivalent processes to obtain equally acceptable citrus juices.

Pulsed electric field treatment has been claimed to produce more acceptable chilled citrus juices than those obtained by conventional thermal treatment. The pectin methylesterase activity and the acceptability of nine juices obtained from Clementine mandarins, Valencia oranges, and Ortanique fruits (hybrid of mandarin and orange), untreated, pasteurized (85 degrees C for 10 s), and treated by pulsed electric fields (25 kV/cm for 330 micros), were evaluated. The treatments, selected to reach a similar level of pectin methylesterase inactivation, produced juices that did not differ in acceptability from each other for the three varieties and in all cases were less acceptable than the untreated juice.

Bacteria↗
PubMed2004

Effect of chronic lithium treatment on the turnover of alpha2-adrenoceptors after chemical inactivation in rats.

One of the most effective psychotherapeutic agents in the treatment of bipolar disease is lithium. Chronic lithium treatment affects some signal transduction mechanisms such as cAMP, cGMP, inositol 1,4,5 P(3), Gi protein, protein kinase C and can also modify gene expression in rat brain. In a previous study, we observed a greater inhibitory effect of lithium on cAMP production after blockade of alpha(2)-adrenoceptors in rat cerebral cortex. Here we examine the influence of chronic lithium treatment on turnover of alpha(2)-adrenoceptors after their inactivation by N-ethoxycarbonyl-2-ethoxy-1,2-dihydroquinoline (EEDQ) in rat cerebral cortex. After treatment with lithium for 10 days (120 mg/kg/day, i.p.), there was a significant increase in the appearance and disappearance rate constants of these adrenoceptors and a significant reduction of their half-life. These results suggest that chronic lithium administration alters the alpha(2)-adrenoceptor turnover in rat brain.

Adrenergic alpha-2 Receptor Antagonists↗
PubMed2003

Application of postmortem lipid peroxidation in heart tissue to the diagnosis of myocardial damage.

The response by the myocardial tissue to injury may be manifested as macroscopical or microscopical lesions or, following an ischemia-reperfusion process, by the formation of reactive oxidant substances (ROS) which, in turn, may increase lipid peroxidation levels in myocardial tissue. The aim of this study was to determine whether the levels of lipid peroxidation in myocardial tissue from subjects who had died from different causes are related to cardiac lesions of ischemic or traumatic aetiology. We studied 825 hypostasis-free samples taken from the myocardial tissue of 75 cadavers. In all cases, a survival period was known to have existed. Lipid peroxidation in myocardial tissue was estimated by the colorimetric determination of malondialdehyde. The highest levels of tissue peroxidation were observed in the group of subjects who died from myocardial infarction. We observed a statistically significant correlation between the extent of peroxidation and the presence of myocardial damage of ischemic or traumatic aetiology. In our study, lipid peroxidation was associated with myocardial injury. The data suggest that the extent of lipid peroxidation in myocardial tissue may be used as a reliable indicator of myocardial damage in support of data obtained by conventional microscopy.

Adolescent↗
PubMed2001

[Antioxidative state and lipid peroxidation in erectile dysfunction: preliminary study].

OBJECTIVE: The aims of this study were to analyze the cavernosal tissue metabolic status of patients with vascular and psychogenic impotence and attempt to establish metabolic differences between these types of erectile dysfunction. METHODS: 103 patients were classified according to the type of erectile dysfunction into group A (vascular) and group B (psychogenic). Diagnosis was based on clinical history, physical examination, intracavernosal injection test, penile echo-doppler assessment, cavernosography-cavernosometry and nocturnal penile test. Cavernosal and peripheral venous blood samples were obtained from each patient and the lipoperoxide (LPO) levels and total antioxidant status (TAS) were determined. SPSS V9.0 was used for the statistical analysis. RESULTS: The mean age was 62 years (range 32-73). Cavernosal blood lipoperoxide levels were statistically higher (p < 0.05) in patients with vascular impotence (2.45 mumol/L) than in those with psychogenic impotence (1.47 mumol/L). Cavernosal blood total antioxidant status was statistically higher (p < 0.05) in patients with psychogenic (1.40 mmol/L) than those with vascular impotence (1.10 mmol/L). The lipoperoxide levels and total antioxidant status for peripheral blood were 1.68 mumol/L vs 1.60 mumol/L and 1.29 mmol/L vs 1.35 mmol/L, respectively, with no statistically significant differences between both groups. CONCLUSIONS: Cavernosal blood lipoperoxide levels and total antioxidant status can be an indicator of cavernosal tissue metabolic status and function.

Adult↗
PubMed1995

Role of nitric oxide on papillary blood flow and pressure natriuresis.

This study examined whether nitric oxide synthesis blockade or potentiation (with N omega-nitro-L-arginine methyl ester [L-NAME] or N-acetylcysteine, respectively) can shift the relations between sodium excretion, papillary blood flow, and renal perfusion pressure. Papillary blood flow was measured by laser Doppler flowmetry. A low dose of L-NAME (3.7 nmol/kg per minute) reduced papillary blood flow only at high arterial pressure (140 mm Hg), but it had no effect on pressure natriuresis. Infusion of 37 nmol/kg per minute L-NAME reduced cortical blood flow by 9% at all perfusion pressures studied, lowered papillary blood flow by 8% and 19% at 120 and 140 mm Hg, respectively, and blunted the pressure-natriuresis response. The administration of 185 nmol/kg per minute L-NAME reduced cortical blood flow by 30% and decreased papillary blood flow by 25% in the range of 100 to 140 mm Hg of arterial pressure. Blockade of nitric oxide synthesis with L-NAME at all doses studied reduced papillary blood flow only at high renal perfusion pressures, but papillary blood flow remained essentially unchanged at low perfusion pressures, thus restoring papillary blood flow autoregulation. N-Acetyl-cysteine (1.8 mmol/kg) increased papillary blood flow by 9% and shifted the relations between papillary blood flow, sodium excretion, and renal perfusion pressure toward lower pressures. This effect of N-acetylcysteine on papillary blood flow was blocked by subsequent L-NAME administration.(ABSTRACT TRUNCATED AT 250 WORDS)

Acetylcysteine↗
PubMed1992

Demonstration of inhibition of cyclic AMP accumulation in brain by very low concentrations of lithium in the presence of alpha-adrenoceptor blockade.

In the present paper, we have studied the effect of lithium on cAMP levels induced by isoprenaline and norepinephrine in the presence of alpha- or beta-adrenoceptor antagonists. Our results show that low lithium concentrations, starting at 0.3 x 10(-3) M, have a significant inhibitory effect on cAMP content induced by isoprenaline in brain tissue pretreated with the alpha-adrenoceptor blocker phenoxybenzamine. On the other hand, the inhibitory effect of lithium on cAMP levels induced by norepinephrine when beta-adrenoceptors are blocked with propranolol, is observed at concentrations starting at 2.5 x 10(-3) M. These results show that in the presence of alpha blockade, low lithium concentrations which are within the therapeutic plasma range for treatment of manic patients, are able to act on an adenylate cyclase-cAMP system coupled to beta-adrenoceptors.

Adrenergic alpha-Antagonists↗
PubMed1991

Role of oxygen free radicals in respiratory distress induced by arachidonic acid in the rat.

The purpose of our present study is the possible implication of oxygen free radicals in the respiratory distress induced in rats by intravenous administration of arachidonic acid (20 mg/kg). The respiratory frequency was measured and plasma TXB2 concentration was assayed by RIA from blood withdrawn 1 min after arachidonic acid administration. The substances studied were: SOD, catalase, mannitol, DMSO, BHT, imidazole. All the drugs, except imidazole, significantly protect the rats from the respiratory distress induced by arachidonic acid. SOD, catalase, BHT and imidazole inhibit whereas mannitol and DMSO increase the plasma levels of TXB2. We suggest that oxygen free radicals generated in the respiratory burst induced by arachidonic acid are mainly responsible for the consequent respiratory distress.

Animals↗
PubMed1985

The effect of BW775C on respiratory distress in the rat induced by arachidonic acid.

BW775C, an inhibitor of the lipoxygenase and cyclo-oxygenase pathways, inhibits the respiratory distress induced by arachidonic acid in rats. The degree of respiratory distress was measured in terms of respiratory rate using electrodes implanted at each side of the thorax. Indomethacin, an inhibitor of the cyclooxygenase pathway, failed to influence the respiratory distress induced by arachidonic acid. The results implicate the lipoxygenase pathway, i.e. the leukotrienes synthesis inhibition, in the respiratory distress induced by arachidonic acid.

4,5-Dihydro-1-(3-(trifluoromethyl)phenyl)-1H-pyraz↗
PubMed1977

Prolactin inhibiting activity of dopamine-free subcellular fractions from rat mediobasal hypothalamus.

In order to check the hypothesis of an identity of dopamine (DA) and prolactin inhibiting activity (PIF), their subcellular distribution was studied in the mediobasal hypothalamus (MBH) and the striatum, which served as a control structure. PIF was tested both in vivo and on pituitary incubates. Fractions were also assayed after adsorption of their catecholamine content on alumina, as well as in presence of haloperidol or alpha-flupentixol, potent DA receptor inhibitors. In the MBH, PIF was evenly distributed in the 17,000 g supernatant (S2) and in the crude mitochondrial fraction (P2) which contains synaptosomes. PIF activity was completely removed by alumina adsorption of S2, but not of P2 in spite of an over 99.9% elimination of DA. In contrast, striatal PIF activity was detected only in P2, and disappeared completely upon alumina adsorption, thus indicating that, in this structure, it is entirely due to DA. Addition of haloperidol (10--5M) or alpha-flupentixol (10--6M) reduced PIF activity of crude MBH homogenates, but no longer affected it after alumina adsorption. Quantitative studies suggest that only half of the total MBH PIF activity is accounted for by DA. It is concluded that the MBH contains dopamine-free PIF, which, as already shown for several other neurohormones, is exclusively distributed in nerve-endings.

Animals↗
PubMed1976

Effect of suckling on plasma prolactin and hypothalamic monoamine levels in the rat.

In lactating rats that were separated from their pups for 8 hours, suckling induced a rapid rise in plasma prolactin levels. Correlatively, it induced a depletion in dopamine (DA) and serotonin (5-HT) Concentrations within the hypothalamus as early as 5 min after the onset of suckling. This depletion lasted as long as the stimulus was maintained. A parallel increase in the level of the metabolite of 5-HT, 5-hydroxyindolacetic acid (5-HIAA), was observed. Under these conditons, the ratio of 5-HIAA/5-HT is augmented. This ratio is a good index of turnover of the transmitter. Suckling affected neither the content of noradrenaline (NA) in the hypothalamus nor the levels of any amine tested in the cerebral cortex. When pups were separated from their mother for 24 hours, suckling no longer resulted in changes in either plasma prolactin levels or hypothalamic DA, 5-HT, or 5-HIAA concentrations. We have concluded that the activation of a discrete system of 5-HT containing neurons is associated with the triggering effect of suckling on prolactin release.

Animals↗