Browsing by Author "Domínguez, María del Carmen"

In order to study the effect of epinephrine on the rate of esterification of fatty acids in adipose tissue, pieces of epididymal fat pad were incubated in KRB in the presence of purified albumin, glucose and either 1-14C-glycerol, 1-"C-glucose or 6-"Cglucose. Epinephrine enhances the production of glycerol but reduces the uptake of I YC-glycerol by the tissue and its conversion to 14CO,, "C-fatty acids and "C-glyceride glycerol. When the change in specific activity of the tracer is taken into account the effect of epinephrine on the utilization of glycerol by the tissue is only observed in the reduction of glyceride glycerol synthesis. When "C-labelled glucose was used as tracer, epinephrine enhances both the production of "CO2 from 6-"C-glucose and the synthesis of "C-glyceride glycerol from 1-"C and 6- 1 'C-glucose. The contrasting effects of epinephrine on the glyceride glycerol formation from glycerol and from glucose can explain the difficulties found in observing any change in the net rate of esterification of fatty acids by adipose tissue.

To study the kinetics of glycerol utilization by adipose tissue in vitro as function of the concentrations of both glycerol and glucose in the incubation media, pieces of epididymal fat pad from fed rats were incubated for different times in Krebs Ringer bir:arbonate supplemented with 1-"C-glycerol and purified albumin. An increase in the concentration of glycerol in the medium produces a decrease in the formation of "CO2 and "C-lipids from 1-"C-glycerol. When the decrease in the specific activity of the tracer is considered to calculate the respective velocities, it turns out that glycerol actually enhances the rate of synthesis of both CO2 and glyceride glycerol. Glucose enhances the rate of synthesis of CO2 and fatty acids from glycerol but decreases the rate of glyceride glycerol synthesis from the same substrate. While the Km of the glycerol effect is much lower that the physiological concentrations of glycerol the Ka and Ki of the glucose effects are above or close to its concentration in blood. The results are discussed in terms of the competitive effects of glucose and glycerol for the synthesis of ix-glycerophosphate and the necessity of glucose for lipogenesis from glycerol in adipose tissue.

The effects of 2-deoxy-D-glucose (2DG), oligomycin and theophylline on the in vitro production and metabolism of glycerol and its response to insulin and epinephrine were studied in epididymal fat pads from fed rats. 2-DG failed to affect basal or epinephrine stimulated glycerol production but it decreased the uptake of 1-14C-glycerol by the tissue and its conversion to glyceride-glycerol Oligomycin also failed to affect the basal production of glycerol but it in· hibited the effect of epinephrine on this parameter as well as the uptake and utilization of 1-14-C-glyceroL Theophylline enhanced the production of glycerol by the tissue and this effect was not further augmented by epinephrine. Theophylline also inhibited the uptake and utilization of 1-14C-glycerol; the most pronounced effect of theophylline was observed in the formation of 14C-fatty acids from 1.14c. glycerol in the presence of glucose. Insulin, but not epinephrine, decreased the inhibitory effect of theophylline on glycerol utilization. It is concluded that these compounds af. feet more intensely the ability of adipose tissue to metabolize glycerol than to release it through lipolysis. The pathway for glycerol utilization in adipose tissue appears to be more sensitive to changes in the availability of ATP than the mechanisms responsible for the release of glycerol fom the tissue.

En el presente estudio hemos determinado la influencia de variaciones de glicerol y glucosa sobre la metabolización del propio glicerol por el tejido adiposo de rata incubado in vitro. Con esta finalidad hemos incubado trozos de epidídimo graso de ratas alimentadas en medio de Krebs-Ringer-bicarbonato conteniendo albúmina bovina purificada y glicerol-1-C14 • A distintos tiempos de incubación se han valorado las variaciones en la actividad específica del trazador, para llegar a expresar los datos en unidades de velocidad, en función del glicerol no radiactivo que sale al medio de incubación vía lipólisis y del que es remetabolizado por el propio tejido. Un aumento en la conc.entración de glicerol en el medio de incubación produce un aumento de las velocidades de síntesis de CO2 y glicerol de glicéridos a partir del mismo substrato. La glucosa produce un aumento de las velocidades de síntesis de CO2 y ácidos grasos a partir de glicerol, pero inhibe su conversión a glicerol de glicéridos. Los resultados se estudian en función de los efectos competitivos de la glucosa y el glicerol para la síntesis de ~-glicerofosfato y la necesidad de la glucosa para la lipogénesis a partir de glicerol en tejido adiposo, como fuente energética para la síntesis de ATP y de coenzimas reducidos para la síntesis de ácidos grasos.

Background: In areas of high exposure to grass pollen, allergic patients are frequently sensitized to profilin, and some experience severe profilin-mediated food-induced reactions. This specific population of patients is ideal to study the relationship between respiratory and food allergies. Objective: We sought to determine the role of oral mucosal epithelial barrier integrity in profilin-mediated allergic reactions. Methods: Thirty-eight patients with profilin allergy stratified into mild or severe according to their clinical history and response to a profilin challenge test and 6 nonallergic subjects were recruited. Oral mucosal biopsies were used for measurement of CD11c, CD3, CD4, tryptase, claudin-1, occludin, E-cadherin, and vascular endothelial growth factor A levels; Masson trichrome staining; and POSTN, IL33, TPSAB, TPSB, and CMA gene expression analysis by using quantitative RT-PCR. Blood samples were used for basophil activation tests. Results: Distinct features of the group with severe allergy included the following: (1) impaired epithelial integrity with reduced expression of claudin-1, occludin, and E-cadherin and decreased numbers of epithelial cells, which is indicative of acanthosis, higher collagen deposition, and angiogenesis; (2) inflammatory immune response in the mucosa, with an increased number of CD11c1 and CD41 infiltrates and increased expression of the cytokine genes POSTN and IL33; and (3) a 10-fold increased sensitivity of basophils to profilin. Conclusions: Patients with profilin allergy present with significant damage to the oral mucosal epithelial barrier, which might allow profilin penetration into the oral mucosa and induction of local inflammation. Additionally, severely allergic patients presented with increased sensitivity of effector cells. (J Allergy Clin Immunol 2019;143:681-90.)

The uptake and utilization of [1 -14C]glycerol was determined in pieces of rat epididymal fat-pads incubated in Krebs-Ringer bicarbonate buffer containing albumin. Insulin (200µunits/ml), adrenaline (epinephrine; 0.5µg/ml) and glucose (0, 5, 15 and 20IDM) were added to the medium. Changes in the specific radioactivity of the tracer during the incubation were taken into account in calculating the rate of glycerol utilization. Adrenaline decreased glycerol uptake, whereas insulin plus adrenaline increased it. The rate of incorporation of glycerol into glycerides was decreased by adrenaline and insulin, singly or together. Insulin increased the rate of formation of CO2 and fatty acids from glycerol. The formation. of CO2 and fatty acids was further. enhanced by insulin plus adrenaline. The decrease in glycerol uptake induced by adrenaline, the decrease in incorporation of glycei;ol into glycerides induced by insulin and insulin plus adrenaline and the synthesis of fatty acids were dependent on the presence of glucose in the medium. Thus insulin and adrenaline act on glycerol utilization in adipose tissue and some of their effects are ~ediated by action on glucose metabolism, but others are independent of this.