Facultad de Ciencias Médicas

About: Facultad de Ciencias Médicas is a based out in . It is known for research contribution in the topics: Population & Fatty acid. The organization has 4833 authors who have published 3708 publications receiving 38112 citations.

Therapeutic application of melatonin in mild cognitive impairment.

Abstract: Mild cognitive impairment (MCI) is an etiologically heterogeneous syndrome defined by cognitive impairment in advance of dementia. We previously reported in a retrospective analysis that daily 3 - 9 mg of a fast-release melatonin preparation given p. o. at bedtime for up to 3 years significantly improved cognitive and emotional performance and daily sleep/wake cycle in MCI patients. In a follow up of that study we now report data from another series of 96 MCI outpatients, 61 of who had received daily 3 - 24 mg of a fast-release melatonin preparation p. o. at bedtime for 15 to 60 months. Melatonin was given in addition to the standard medication prescribed by the attending psychiatrist. Patients treated with melatonin exhibited significantly better performance in Mini-Mental State Examination and the cognitive subscale of the Alzheimer's disease Assessment Scale. After application of a neuropsychological battery comprising a Mattis´ test, Digit-symbol test, Trail A and B tasks and the Rey´s verbal test, better performance was found in melatonin-treated patients for every parameter tested. Abnormally high Beck Depression Inventory scores decreased in melatonin-treated patients, concomitantly with the improvement in the quality of sleep and wakefulness. The comparison of the medication profile in both groups of MCI patients indicated that 9.8% in the melatonin group received benzodiazepines vs. 62.8% in the non-melatonin group. The results further support that melatonin can be a useful add-on drug for treating MCI in a clinic environment.

Liver glucokinase: An overview on the regulatorymechanisms of its activity

Abstract: Blood glucose is the primary cellular substrate and in vivo must be tightly maintained. The liver plays a key role in glucose homeostasis increasing or decreasing glucose output and uptake during fasting and feeding. Glucokinase (GCK) is central to this process. Its activity is modulated in a coordinated manner via a complex set of mechanisms: in the postprandial period, the simultaneous rise in glucose and insulin increases GCK activity by enhanced gene expression, changes in cellular location, and interaction with regulatory proteins. Conversely, in the fasting state, the combined decrease in glucose and insulin concentrations and increase in glucagon concentrations, halt GCK activity. Herein we summarize the current knowledge regarding the regulation of hepatic GCK activity.

Ultrastructural zonation of adrenocortex in the rat.

Abstract: The fine structure of the different zones in the adrenal cortex of the adult rat has been studied under the electron microscope. Four regions mainly differentiated by the mitochondrial morphology, the lipid droplets, and the structure of the ground cytoplasm were recognized. In the glomerular zone mitochondria are thin and elongated with an abundant matrix. The inner structure is characterized by the presence of tubules of 300 A that are straight or bend at an angle and which may be grouped in parallel array giving a pseudocrystalline pattern. The wall of each tubule is a finger-like projection of the inner membrane and its cavity corresponds to the outer chamber of the mitochondrion. In the intermediary zone mitochondria are larger and irregular. The matrix is filled with convoluted tubules and vesicular elements. The lipid droplets are larger and irregular in the glomerulosa and and small in the intermedia. The ground substance is dense and contains free ribosomes in the glomerulosa and starts to be vacuolated in the intermedia. In the fasciculata mitochondria are round or oval and are filled with vesicular elements with a mean size of 450 A. Larger vesicles and more clear elements (vacuoles) are seen near the edge as if their content was diluted. Some of these vacuoles protrude on the surface. In the reticular zone mitochondria are also vesicular but frequently show signs of alteration and disruption. Dense elements recognized as microbodies are observed in the fasciculata but they increase in number in the reticularis. These results are discussed on the light of the so called zonal theory of the adrenal cortex. Two stages in the differentiation of the mitochondria are postulated. The tubular structure of the glomerulosa undergoes a process of disorientation and dilatation of the tubules to form the tubulo-vesicular elements of the intermediary zone. In a second stage of differentiation, by fragmentation of the tubules, the vesicular structure of fasciculata is formed. These findings are discussed from the viewpoint of the relationship between mitochondria and synthesis of steroid hormones. A secretory process that starts within mitochondria by the formation of vesicles and proceeds into the ground cytoplasm, as extruded and more clear vacuoles, is postulated.

Regression of Isoproterenol-Induced Cardiac Hypertrophy by Na+/H+ Exchanger Inhibition

Abstract: Cardiac hypertrophy is often associated with an increased sympathetic drive, and both in vitro and in vivo studies have demonstrated the development of cardiomyocyte hypertrophy in response to either alpha- or beta-adrenergic stimulation. Because an association between the Na+/H+ exchanger and cellular growth has been proposed, this study aimed to analyze the possible role of the antiporter in isoproterenol-induced cardiac hypertrophy. Isoproterenol alone (5 mg/kg IP once daily) or combined with a selective inhibitor of the Na+/H+ exchanger activity (3 mg x kg(-1) x d(-1) BIIB723) was given to male Wistar rats for 30 days. Sex- and age-matched rats that received 0.9% saline IP daily served as controls. Echocardiographic follow-up showed a 33% increase in left ventricular mass in the isoproterenol-treated group, whereas it did not increase in the isoproterenol+BIIB723-treated group. Heart weight-to-body weight ratio at necropsy was 2.44+/-0.11 in controls and increased to 3.35+/-0.10 (P<0.05) with isoproterenol, an effect that was markedly attenuated by BIIB723 (2.82+/-0.07). Intense cardiomyocyte enlargement and severe subendocardial fibrosis were found in isoproterenol-treated rats, and both effects were attenuated by BIIB723. Myocardial Na+/H+ exchanger activity and protein expression significantly increased in isoproterenol-treated rats compared with the control group (1.45+/-0.11 vs 0.91+/-0.05 arbitrary units, P<0.05). This effect was significantly reduced by BIIB723 (1.17+/-0.02, P<0.05). In conclusion, our results show that Na+/H+ exchanger inhibition prevented the development of isoproterenol-induced hypertrophy and fibrosis, providing strong evidence in favor of a key role played by the antiporter in this model of cardiac hypertrophy.

Melatonin and the metabolic syndrome: physiopathologic and therapeutical implications.

Abstract: Metabolic syndrome (MS) patients exhibit sleep/wake disturbances and other circadian abnormalities, and these may be associated with more rapid weight increase and development of diabetes and atherosclerotic disease. On this basis, the successful management of MS may require an ideal drug that besides antagonizing the trigger factors of MS could also correct the disturbed sleep-wake rhythm. Melatonin is an effective chronobiotic agent able to change the phase and amplitude of circadian rhythms. Melatonin has also significant cytoprotective properties preventing a number of MS sequelae in animal models of diabetes and obesity. A small number of controlled trials indicate that melatonin is useful to treat the metabolic and cardiovascular comorbidities of MS. Whether the recently introduced melatonergic agents (ramelteon, agomelatine, tasimelteon) have the potential for treating sleep disorders in MS patients and, more generally, for arresting the progression of disease, merits further investigation.