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Biomedical subjects

E Simón

Publications and source records attributed to E Simón.

At least 19 recordsLinked to original sources
PubMed2006

Microautoradiographic localisation of [3H]sucrose and [3H]mannitol in Robinia pseudoacacia pulvinar tissues during phytochrome-mediated nyctinastic closure.

We have analysed the incorporation of [(3)H]sucrose and [(3)H]mannitol in pulvinar motor cells of Robinia pseudoacacia L. during phytochrome-mediated nyctinastic closure. Pairs of leaflets, excised 2 h after the beginning of the photoperiod, were fed with 50 mM [(3)H]sucrose or [(3)H]mannitol, irradiated with red (15 min) or far-red (5 min) light and placed in the dark for 2-3 h. Label uptake was measured in whole pulvini by liquid scintillation counting. The distribution of labelling in pulvinar sections was assessed by both light and electron microautoradiography. [(3)H]Sucrose uptake was twice that of [(3)H]mannitol incorporation in both red- and far-red-irradiated pulvini. In the autoradiographs, [(3)H]sucrose and [(3)H]mannitol labelling was localised in the area from the vascular bundle to the epidermis, mainly in vacuoles, cytoplasm, and cell walls. Extensor and flexor protoplasts displayed a different distribution of [(3)H]sucrose after red and far-red irradiation. Far-red light drastically reduced the [(3)H]sucrose incorporation in extensor protoplasts and caused a slight increase in internal flexor protoplasts. After red light treatment, no differences in [(3)H]sucrose labelling were found between extensor and flexor protoplasts. Our results indicate a phytochrome control of sucrose distribution in cortical motor cells and seem to rule out the possibility of sucrose acting as an osmoticum.

Autoradiography↗
PubMed2005

Body fat-lowering effect of conjugated linoleic acid is not due to increased lipolysis.

The ability of conjugated linoleic acid (CLA) to reduce adiposity may be due to changes in energy expenditure and/or direct effects on adipocyte lipid metabolism. The aim of the present work was to analyse if CLA supplementation modifies lipolytic activity in adipose tissue from hamsters fed on high-fat diet. Hamsters were divided into two groups and fed on diets supplemented with either 0.5% linoleic acid (control) or 0.5% trans-10,cis-12 CLA. After 6 weeks, animals were fasted overnight and adipose tissues were dissected and weighed. Adipocytes were isolated by collagenase digestion and incubated in Krebs-Ringer bicarbonate buffer with or without several agents acting at different levels of the lipolytic cascade. Adipocyte diameters were measured by microscopy. Adipose tissue DNA content was assessed by spectrophotometry. Animals fed on CLA diet showed significantly reduced adipose tissue mass. No differences between both groups was found for basal lipolysis, lipolytic effects of isoproterenol, forskolin, dibutyryl-cAMP and isobutylmethylxanthine, and pD2 for isoproterenol. A similar total DNA amount was found in adipose tissue of both groups, showing that CLA diet had no effect on total cell number per fat pad. Although DNA content per gram tissue, an indirect reverse index of cell size, was significantly increased in CLA fed hamsters, microscopy did not reveal differences in medium mature adipocyte diameter, nor in cell size distribution between both groups. These results suggest that adipose tissue size reduction induced by trans-10,cis-12 CLA intake is not due to changes in lipolysis. Reduced preadipocyte differentiation into mature adipocytes may account for this fat-lowering effect.

Adipocytes↗
PubMed2003

Effects of conjugated linoleic acid on body fat accumulation and serum lipids in hamsters fed an atherogenic diet.

Conjugated linoleic acid (CLA) refers to a mixture of naturally occurring positional and geometric isomers of linoleic acid that exist in dairy products and meat. The aim of the present work was to study the effects of c-9,t-11 and t-10,c-12 CLA isomers on body fat accumulation and serum lipids in hamsters fed an atherogenic diet. Hamsters were divided in four groups: one group was fed a chow diet (control) and the other three groups were given semi-purified atherogenic diets with 0.5% linoleic acid (LA), c-9,t-11 or t-10,c-12 CLA. Body weight and food intake were measured daily. After 6 weeks, adipose tissues from different anatomical locations and liver were dissected and weighed. Serum glucose, total cholesterol, HDL-c, LDL-c and triacylglycerol levels, as well as total and free cholesterol, triacylglycerol and phospholipid content in liver were determined by enzymatic methods. No differences in either energy intake or final body weight were found. The addition of t-10,c-12 CLA reduced fat accumulation and led to lower serum cholesterol, as compared with LA group. Nevertheless the level remained higher than in the control animals. The reduction in serum cholesterol was limited to LDL-c. This isomer also reduced triacylglycerol content in liver but did not modify serum triacylglycerol level. In summary, the present study demonstrates that t-10,c-12 CLA is the biologically active agent when anti-obesity and hypocholesterolaemic properties of CLA are considered. In contrast, the isomer c-9,t-11 has no effect on lipid metabolism in hamsters.

Adipose Tissue↗
PubMed2002

[Leptin and obesity].

Obesity appears as a result of the balance between the individual's calorie consumption and energy expenditure. There are numerous neuroendocrinological factors responsible for regulating the energy metabolism; however, it was the discovery of the leptin that opened the way for numerous investigations destined to lay bare the mechanisms involved in this homeostasis. The leptin is a peptide of 167 amino acids, with a signal sequence of 21 amino acids that split up before the leptin enters the circulatory torrent. The white adipose tissue is the main producer of leptin, acting as a "marker" of the body's energy reserves. Leptin intervenes in different physiological processes such as the regulation of the energy balance, the control of appetite and body weight, the metabolism of fats and glucides or reproduction, amongst others. There are numerous ob receptors on the central nervous system and in different regions of the hypothalamus that are involved in part of the observed effects of this hormone. Besides, there are ob receptors in numerous peripheral tissues such as the lung, kidney, liver, skeletal muscle, adipose tissue, testicles, pancreatic islets and haematopoietic cells. The study of its regulation, connections and effects on the central nervous system are proving to be essential for an understanding of the system of regulation of the energy balance and of the mechanisms involved in the development of obesity.

English Abstract↗
PubMed2001

A screening for high copy suppressors of the sit4 hal3 synthetically lethal phenotype reveals a role for the yeast Nha1 antiporter in cell cycle regulation.

A screening for multicopy suppressors of the G(1)/S blockage of a conditional sit4 hal3 mutant yielded the NHA1 gene, encoding a Na(+),K(+)/H(+) antiporter, composed of a transmembrane domain and a large carboxyl-terminal tail, which has been related to cation detoxification processes. Expression of either the powerful Saccharomyces cerevisiae Ena1 Na(+)/H(+)-ATPase or the Schizosaccharomyces pombe Sod2 Na(+)/H(+) antiporter, although increasing tolerance to sodium, was unable to mimic the Nha1 function in the cell cycle. Mutation of the conserved Asp residues Asp(266)-Asp(267) selectively abolished Na(+) efflux without modifying K(+) efflux and did not affect the capacity of Nha1 to relieve the G(1) blockage. Mutagenesis analysis revealed that the region near the carboxyl-terminal end of Nha1 comprising residues 800-948 is dispensable for sodium detoxification but necessary for transport of K(+) cations. Therefore, this portion of the protein contains structural elements that selectively modulate Nha1 antiporter functions. This region is also required for Nha1 to function in the cell cycle. However, expression of the closely related Cnh1 antiporter from Candida albicans, which also contains a long carboxyl-terminal extension, although allowing efficient K(+) transport does not relieve cell cycle blockage. This indicates that although the determinants for Nha1-mediated regulation of potassium transport and the cell cycle map very closely in the protein, most probably the function of Nha1 on cell cycle is independent of its ability to extrude potassium cations.

Amino Acid Sequence↗
PubMed2001

Intracellular localization of phytochrome in Robinia pseudoacacia pulvini.

The intracellular localization of phytochrome in the pulvini of Robinia pseudoacacia L. was analyzed by immunogold electron microscopy after red (R; 15 min) and far-red (FR; 5 min) irradiation 2 h after the beginning of the photoperiod. Screening of the available antibodies by immunoblotting demonstrated that none of the oat (Avena sativa L.) anti-phytochrome A (phy A) monoclonal antibodies) (MAbs) detected Robinia phytochrome. A putative Robinia phy A was detected by immunoblotting using a MAb to mustard (Sinapis alba L.) phy A (CP 2/9). No cross-reactivity was observed in blots probed with a MAb against Cucumis sativus L. phy B (mAT1). Ultrathin sections of LR White resin-embedded pulvini were immunolabelled with CP 2/9 MAb. The labelling was restricted to cortical cells and there was no evidence of labelling either in the vascular system or in the epidermis. The pattern of labelling was the same in both extensor and flexor cells irrespective of whether phytochrome was in the far-red-absorbing (Pfr) state or had reverted to the red-absorbing (Pr) form. Isolated labels and clusters of labels were randomly distributed throughout the cytoplasm. Gold particles were also found in the interior of nuclei, chloroplasts and mitochondria.

Biological Transport↗
PubMed2001

[Radial free flap with drainage through the cephalic vein dissected up to the deltoid region: a resource in the absence of receptor veins].

Repeated treatments on the neck in head and neck oncological patients make more and more difficult to elaborate microvascularized flaps because sometimes it is necessary to sacrifice receptor veins. In this paper it is showed one way of solving this problem, by dissection of the cephalic vein towards the deltoid region, keeping the venous pedicle intact. In this fashion venous anastomosis is avoided, getting efficient blood drainage. Simplicity and efficiency of this technique make possible thinking about it even with existing receptors veins. The main inconvenience is the surgical scare on the anterior region of the arm.

Arm↗
PubMed2000

Effects of medium-chain fatty acids on body composition and protein metabolism in overweight rats.

The lack of efficiency of classical treatments for obesity has led to propose alternative strategies. In order to obtain information about the effects of dietary fatty acid composition on body fat and protein metabolism, overweight female rats were fed on isoenergetic diets, using either medium-chain (MCT) or long-chain (LCT) triglycerides as a lipid source. After 23 days, the MCT group had mildly decreased body weight but greatly reduced adipose tissue depots. All fat depots were significantly diminished. MCT-fed rats showed a decrease in some hormones involved in energy balance, such as leptin and triiodothyronine. Feeding MCT resulted in improvements in nitrogen balance. Muscle protein content was similar in both treatments despite an increase in protein degradation in the MCT group. The present data clearly show that a diet with MCT as lipid fuel depresses weight gain and fat stores, relative to a standard LCT diet.

Adipose Tissue↗
PubMed2000

Superior vena cava syndrome during the treatment of pulmonary tuberculosis in an HIV-1 infected patient.

Tuberculosis is nowadays an uncommon cause of superior vena cava syndrome (SVCS). We report the case of an HIV-infected patient who presented with respiratory symptoms accompanied by cervical and mediastinal lymphadenopathy. Sputum examination showed acid-fast bacilli, and treatment was instituted with isoniazid, rifampicin, pyrazinamide and ethambutol. A few days later SVCS developed, presumably as a consequence of inflammatory lymphadenitis. With corticosteroids, all symptoms disappeared. To our knowledge, no cases of SVCS provoked by this kind of paradoxical reaction have been described previously.

AIDS-Related Opportunistic Infections↗
PubMed1999

Effect of high-fat diet on lypolisis in isolated adipocytes from visceral and subcutaneous WAT.

Variations in total energy intake and composition of daily food play an important role in the regulation of metabolic processes and so, in the control of body weight. This study was designed in order to investigate the effect of a high-fat diet on lipolysis in isolated adipocytes. For this purpose, fourteen Wistar rats were divided into two groups and fed either a standard-fat diet or a high-fat diet ad libitum for 7 weeks. Adipocytes were prepared from fat pads by collagenase digestion and incubated in vitro in the absence or presence of various lipolytic agents. Lipolysis was measured by the release of glycerol into the medium during 90 min of incubation. We observed that a high amount of fat in the diet induced an enlargement of adipose tissue, which was accompanied by a reduction of beta-adrenergic agonist-induced lipolysis, that could be due to a loss of beta(1) and beta(3)-adrenoceptor number or to alterations of their coupling to adenylate-cyclase through the guanine nucleotide regulatory protein. New data about regional differences were provided by comparing two adipose locations (subcutaneous and visceral).

Adipocytes↗
PubMed1998

Hyperleptinaemia in mice induced by administration of the tyrosine hydroxylase inhibitor alpha-methyl-p-tyrosine.

Alpha-methyl-p-tyrosine (alphaMPT), an inhibitor of tyrosine hydroxylase, was administered to mice to block noradrenaline synthesis. Ten hours after injection of alphaMPT there was a 6-fold increase in plasma leptin. The level of ob mRNA in epididymal white adipose tissue was also increased, but UCP1 mRNA in brown fat fell. In contrast to lean mice, ob mRNA in white fat of ob/ob mice was not increased by alphaMPT. AlphaMPT raised plasma leptin in fasted as well as fed mice. Hyperleptinaemia was attenuated by treatment with a beta3-adrenoceptor agonist. Inhibition of noradrenaline synthesis leads to the rapid induction of hyperleptinaemia; it is suggested that sympathetic tone plays a pivotal role in regulating leptin production.

Adipose Tissue↗