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J Casado

Publications and source records attributed to J Casado.

At least 19 recordsLinked to original sources
PubMed1995

Induction of the high-affinity Na(+)-dependent glutamate transport system XAG- by hypertonic stress in the renal epithelial cell line NBL-1.

The high-affinity Na(+)-dependent glutamate transport system XAG- is induced (threefold increase in Vmax. with no change in Km) by hypertonicity in the renal epithelial cell line NBL-1. This effect is dependent on protein synthesis and glycosylation and is accompanied by an increase in EAAC1 mRNA levels. Other Na(+)-dependent transport systems in this cell line do not respond to hypertonic stress. In contrast to recent findings [Ruiz-Montasell, Gomez-Angelats, Casado, Felipe, McGivan and Pastor-Anglada (1994) Proc. Natl. Acad. Sci. U.S.A. 91, 9569-9573] showing that increased system A activity after hyperosmotic shock results from induction of a regulatory protein, this is the first demonstration that hypertonicity may increase the expression of the gene for an amino acid transport protein itself.

Amino Acid Transport System X-AG↗
PubMed1995

Ontogeny of L-alanine uptake in plasma membrane vesicles from rat liver.

Alanine uptake into liver plasma membrane vesicles was studied at different stages of postnatal rat development. Before weaning, alanine hepatic uptake showed lower values for the global KM than after weaning (0.34, 0.77, 1.45, and 1.61 mM for 1-, 15-, and 28-d-old and adult rats, respectively). Alanine uptake capacity increased progressively until reaching maximum values in the adult state (values for Vmax: 0.078, 0.199, 0.317, and 0.613 nmol alanine/mg protein/3 s for 1-, 15-, and 28-d-old and adult rats, respectively). These results seem to point to a prevalence of a high affinity, low capacity alanine transport component (traditionally assumed to be attributable to system A) in newborn and suckling rats, in agreement with our previous results on isolated hepatocytes (Martínez-Mas JV, Casado J, Felipe A, Marin JJG, Pastor-Anglada M: Biochem J 293: 819-824, 1993). The suckling-weaning developmental transition seems to play a role in establishing the pattern of adult hepatic alanine transport characterized by a higher capacity but a lower affinity (because most alanine is taken up by system ASC) inasmuch as KM values show a 100% increase after weaning, although Vmax values continue to increase steadily until the adult age.

Alanine↗
PubMed1994

Up-regulation of liver system A for neutral amino acid transport in euglycemic hyperinsulinemic rats.

To determine the role of insulin on the in vivo modulation of liver system A activity, we used the euglycemic hyperinsulinemic clamp coupled to the measurement of solute uptakes into plasma membrane vesicles partially purified from livers of hyperinsulinemic rats and their saline-infused controls. The clamp was performed in chronically catheterized rats, either in the fasted state, 24 h after surgery (Group I), or after 3 days of recovery (Group II). System A activity, measured as the MeAIB-inhibitable L-alanine uptake, was selectively induced by hyperinsulinemia, although the effect was much greater in Group II than in Group I rats (137% vs. 24% over the basal values, respectively). This might be explained by the higher basal levels found in those liver plasma membrane vesicles from Group I fasted animals. Hyperinsulinemia also decreased blood amino acids but to a similar extent in both experimental groups. This suggests that amino acid depletion by itself may not cause up-regulation of system A. Other transport activities involved in neutral amino acid transport (Systems ASC, N and L) were not modified by the clamp. The induction of system A cannot be explained by changes in the dissipation rate of the Na+ transmembrane gradient, because the differences between insulin- and saline-infused rats remained even when the electrochemical Na+ gradient was disrupted in the presence of monensin. Thus, hyperinsulinemia might induce an increase in the number of transporters inserted into the plasma membrane.

Amino Acid Transport Systems↗
PubMed1992

Role of the rat liver in the disposal of a glucose gavage.

An oral gavage of either 3, 1, or 0.1 mmoles of glucose was given to rats under standard feeding conditions or food deprived for 24 hr. The blood flow of the portal and suprahepatic veins as well as the hepatic balances for glucose, lactate, alanine and pyruvate were estimated. In fed rats, after the administration of an oral 3 mmoles load, the liver actually released 310 mumoles of glucose and 90 of lactate, amounts that could be accounted for by the uptake of alanine (148 mumoles) and small loss of glycogen (275 mumoles of glycosyl residues). In starved rats, however, the liver took a very high proportion (c. 71%) of the glucose absorbed, both as glucose (780 mumoles), lactate and pyruvate (892 mumoles) or alanine (134 mumoles). The synthesis of glycogen was considerably limited, accounting for only 205 mumoles, and leaving practically one mmol of glucose equivalent energy available for liver function and the synthesis of other compounds. Practically all glycogen was synthesized directly from glucose, since the synthesis from 3 C carriers was less than a 5%. Smaller gavages (1 or 0.1 mmoles) resulted in a much lower liver uptake activity. The strikingly different activity of the liver with respect to the available glucose and 3 C fragments could not be explained alone by the circulating levels of these compounds, suggesting a very deep influence of the intestine in hepatic function. The liver plays a very passive role in fed animals, with a very small involvement in the disposal of a glucose load, whereas it takes on an important role when the overall availability of energy is diminished.

Alanine↗
PubMed1992

Intestinal handling of a glucose gavage by the rat.

An oral gavage of either 3, 1 or 0.1 mmoles of 14C-labelled glucose was given to rats under standard feeding conditions or food deprived for 24 hr. The fate of the glucose label was determined at 10, 15, 30 and 60 min after gavage; at 60 min 40% of the glucose was absorbed in fed rats (60% in food deprived). The portal vein blood flows were determined and the levels of glucose, lactate, alanine and pyruvate, and their radioactivity, as well as that of CO2 were measured in both portal and arterial blood. The net computed glucose and 3-carbon carriers (lactate, alanine and pyruvate) actually released into the portal system by the intestine was lower than the amount of glucose taken up from the intestinal lumen in one hour. Oxidation to 14CO2 accounted for a 12-15% of the absorbed glucose. The size of the gavage deeply affected the proportion of glucose released into the portal blood (c. 50% with a 3 mmoles gavage and practically nil with a 0.1 mmoles gavage), but it affected much less the generation of lactate and other 3 C carriers. In fed rats, the net intestinal balance of non-radioactive glucose was negative, and that of lactate positive; when radioactive glucose was considered, the pattern was inverted. In starved rats, both glucose and lactate were released in large proportions by the intestine, but alanine efflux was lower. It can be concluded that the intestine consumes a considerable proportion of glucose in the fed state. Glucose handling by the intestine is compartmentalized in two functional circuits: glucose is taken up from the arterial blood and used for intestinal metabolism and lactate production, luminal glucose is absorbed mainly unaltered and transferred to the portal blood. Thus, the generation of lactate is mainly related to the availability of arterial glucose. In addition to the release of the ingested glucose as 3 C carriers or glucose, an extraportal pathway for glucose transfer into the bloodstream is postulated.

Animals↗
PubMed1992

Comparison of results of percutaneous transluminal coronary angioplasty with and without selective requirement of surgical standby.

To determine the outcome of percutaneous transluminal coronary angioplasty (PTCA) with the use of 2 different strategies of surgical coverage, the results of 1,283 consecutive PTCAs were analyzed. In 269 procedures (21%) (patients considered at high risk should acute vessel closure occur--standby group) the operating room and the surgical team were ready for an immediate intervention. In the remaining 1,014 procedures (79%) (backup group), although the surgical team was "in house," they were not necessarily ready for an immediate intervention. Mean age of the population was 58 +/- 10 years and 84% of patients were men. Coronary risk factors, medical treatment, clinical indication for PTCA, previous coronary surgery and left ventricular ejection fraction were similar in both groups. Dilatation was more frequently multiple (23 vs 16%, p less than 0.05), or performed in the left anterior descending coronary artery (71 vs 46%, p less than 0.001), in bypass grafts (4 vs 2%, p less than 0.02), in proximal coronary segments (72 vs 57%, p less than 0.001) or in lesions at bifurcation (35 vs 28%, p less than 0.02) in the standby than in the backup group, respectively. PTCAs were less frequently performed during the same diagnostic procedure (15 vs 34%, p less than 0.001) in the standby group. Angiographic success was obtained in 91 and 92% of the attempted lesions and PTCA success in 89 and 88% of the procedures in the standby and backup groups, respectively. The incidence of death (1 vs 0.7%), acute myocardial infarction (2.9 vs 2.7%) and emergency surgery (0.7 vs 0.1%) was also similar in both groups.(ABSTRACT TRUNCATED AT 250 WORDS)

Aged↗
PubMed1992

Quantitative structure-activity relationship study of the biophysicochemical behavior of nitrosamine.

The partition coefficients of 14 aliphatic nitrosamines were measured in six water-organic solvent systems. Correlations between Hansch's hydrophobic parameter (pi) and Kier and Hall's topological index (1 chi) allowed pi to be substituted by 1 chi in the structure-activity correlations of the carcinogenicity data of the nitrosamines studied. The use of high-performance liquid chromatographic capacity factors of nitrosamines in these correlations is also discussed.

Chemical Phenomena↗
PubMed1992

Rat intestinal amino acid balances after the administration of an oral protein load.

The intestinal amino acid balances in rats given an oral load of protein were measured three hours after the gavage. During that period, about one half of the nitrogen from the protein given appeared as net balance in the portal blood. The release of amino acids was not a continuous process, since two peaks of maximal intestinal efflux were found at 1 and 2.5 hours after gavage. This pattern followed that of portal blood flow with a 30 minute delay. Under prandial conditions, the intestine showed a net uptake of glutamine, aspartate, serine, threonine, phenylalanine, tyrosine, leucine, isoleucine and valine. It also showed a net production of alanine, glutamate, ornithine skeleton (arginine + citrulline + ornithine) and ammonia. There was also a surge of taurine, attributed to reabsorption of secreted taurine conjugates. There was a net unchanged absorption of glycine, proline, lysine and histidine, with respect to their proportions in the protein administered. The results suggest that the amino acid metabolism in the intestine under prandial conditions is much less passive than is generally assumed. The intestinal action upon the luminal amino acids is not limited to absorption, but is directly implied in their transformation to complement the ensuing homeostatic action of the liver upon them.

Amino Acids↗
PubMed1992

[The evaluation of the results after coronary angioplasty by intracoronary Doppler and quantitative angiography. The correlation of both methods].

To study the importance of measuring coronary flow reserve immediately after coronary angioplasty we have analysed the results obtained after 28 angioplasties performed in 21 patients. Coronary flow reserve was measured with a 3F intracoronary catheter selectively placed in the dilated artery. Corresponding coronary angiography was analysed with an automatic edge detection program (ARTREK) and visual estimation. Coronary flow reserve increased in 26/27 cases after angioplasty from 2.4 +/- 1.3 to 4.1 +/- 2.7 (p less than 0.001). A correlation was found between minimal luminal area and minimal luminal diameter after coronary angioplasty, and coronary flow reserve (r = 0.46; p less than 0.05 and r = 0.47; p less than 0.05, respectively). The finding of a normal coronary flow reserve (greater than or equal to 3.5), had a 100% specificity but only 56% sensitivity to detect angiographic success (residual stenosis less than 50%). However 47% of patients with angiographic success did not reach normal values of coronary flow reserve. Visual estimation of the stenosis had a good correlation with automatic evaluation but significant scattering was observed at visual levels less than or equal to 25%. Visual assessment underestimated residual stenosis in all but one of the procedures. We conclude that coronary flow reserve is a potentially useful index for assessing the results after angioplasty that may complement coronary angiography. Nonetheless substantial differences between both methods exist in a significant number of cases. The relative merits of both methods, as well as the particular circumstances in which coronary flow reserve should be used, require further studies.

Angioplasty, Balloon, Coronary↗
PubMed1992

[Transluminal percutaneous coronary angioplasty of the left coronary artery].

This paper describes our preliminary experience with left main coronary angioplasty in 8 patients (9 procedures). In 6 patients the left main coronary artery was "protected" either by previous by-pass surgery (4 patients) or by collateral vessels from the right coronary artery (2 patients). Three patients had a total occlusion of the left main coronary artery and 2 of them had a recent or acute myocardial infarction and the coronary angiogram suggested a thrombotic occlusion of the infarct-related artery. Three patients were not considered surgical candidates and an additional patient, who was in cardiogenic shock, required an emergency coronary angioplasty as "rescue" procedure. A successful dilatation was achieved in 6 patients (including a patient with successful deployment of a Palmaz-Schatz stent) but, unfortunately, one them eventually died 7 days later from a femoral sepsis related to the procedure. However in the 2 remaining patients--with a total occlusion of the left main coronary artery in relation with a myocardial infarction--the dilatation procedures were unsuccessful. One patient underwent a successful repeat coronary angioplasty for restenosis of left main coronary artery. Our preliminary experience confirms previous reports suggesting the value of coronary angioplasty in patients with left main coronary artery disease providing a careful selection of possible candidates is performed prior to the procedure.

Adult↗
PubMed1991

Amino acid uptake by liver of genetically obese Zucker rats.

Alanine and glutamine uptake by the liver of 50-52-day-old genetically obese Zucker rats and their lean littermates has been studied. The net uptake in vivo of L-alanine is 2-fold higher in the obese animals. No significant change in L-glutamine net balance was found. We also studied the Na(+)-dependent uptake of L-alanine and L-glutamine into plasma-membrane vesicles isolated from either obese- or lean-rat livers. Vmax. values of both L-alanine and L-glutamine transport were 2-fold higher in those preparations from obese rats. No change in Km was observed. As suggested by inhibition studies, this seemed to be mediated by an enhancement of the activities of systems A, ASC and N. We conclude that the liver of the obese Zucker rat is extremely efficient in taking up neutral amino acids from the afferent blood, which results in an enhanced net uptake of L-alanine in vivo. The changes in transport activities at the plasma-membrane level might contribute to increase amino acid disposal by liver, probably for lipogenic purposes, as recently reported by Terrettaz & Jeanrenaud [Biochem. J. (1990) 270, 803-807].

Alanine↗
PubMed1991

Differences in L-alanine uptake by livers of Wistar and lean Zucker rats.

The L-alanine uptake by livers of Wistar and lean Zucker rats has been studied. The hepatic uptake and fractional extraction rates of alanine were estimated in 50-55 day old rats. No significant differences in amino acid concentrations and blood flows in afferent and efferent liver vessels were seen in lean Zucker rats when compared with Wistar rats. However, the hepatic uptake (1.6 +/- 0.1 and 0.7 +/- 0.1 mumol/min/100 g bw, p less than 0.01) and the fractional extraction (26.8 +/- 2.1 and 15.2 +/- 3.1%, p less than 0.05) were much lower in Zucker than in Wistar rats. The hepatic active transport of L-alanine was determined in vitro using isolated plasma membrane vesicles. Vesicles isolated from livers of lean Zucker rats showed similar values of Km (2.5 +/- 0.7 vs. 2.0 +/- 0.5 mM for Wistar and Zucker respectively, N.S.), but lower values of Vmax when compared with Wistar rats (1.1 +/- 0.1 vs 0.6 +/- 0.005 nmol/mg prot 5 s, p less than 0.01, for Wistar and lean Zucker rats respectively). These results indicate that, the liver of lean Zucker rats concentrates alanine less efficiently than the liver of Wistar rats. This fact correlates well with a lower capacity of the Na(+)-dependent L-alanine transport in liver plasma membrane vesicles from lean Zucker rats.

Alanine↗
PubMed1991

Rat liver amino acid balances after the administration of an oral protein load.

The hepatic balances of amino acids, ammonia and urea have been measured in rats for three hours after receiving a protein load. The liver took up practically all of the portal ammonium. Alanine was retained to a large extent during all three hours. Other portal amino acids, mainly essential amino acids, were largely retained in about one hour after the gavage, to be released in a similar proportion thereafter. The other amino acids were also retained and then released, but to a lower extent. These amino acids were used in part by the liver for the synthesis and release of urea, which appearance in hepatic vein peaked at two hours after the protein administration.

Administration, Oral↗
PubMed1991

[The results of percutaneous transluminal coronary angioplasty in lesions with thrombi].

Previous studies have suggested that the results of coronary angioplasty are poorer when the attempted lesion has a thrombus associated. With the aim of assessing the results of coronary angioplasty in lesions with thrombus, 1,192 consecutive coronary lesions attempted were prospectively analyzed. Of these, 88 (7%) had associated an angiographic intraluminal filling defect consistent with thrombus (group I) and were compared with the remaining 1,104 lesions (93%) without thrombus (group II). Age (56 +/- 12 vs 59 +/- 10 years) was similar in both groups, but patients in group I required more frequently dilatation after a myocardial infarction (acute phase or following thrombolytic therapy) (36% vs 12%, p less than 0.005) but infrequently for stable angina (6% vs 21%, p less than 0.005). Left ventricular ejection fraction (60 +/- 13% vs 63 +/- 12%) and the number of diseased vessels (1.46 +/- 0.7 vs 1.58 +/- 0.8) were similar in groups I and II, respectively, but lesions in group I were less frequently located in the left anterior descending coronary artery (35% vs 53%, p less than 0.025). Furthermore, lesions in group I were more frequently total occlusions (35% vs 4%, p less than 0.001), and were more severe (94 +/- 6% vs 87 +/- 8%, p less than 0.005), eccentric (81% vs 54%, p less than 0.005), irregular (72% vs 32%, p less than 0.005) and more frequently located at bend points (31% vs 17%, p less than 0.05). Primary angiographic success was lower in group I (79% vs 92%, p less than 0.001) and, after dilatation, the incidence of luminal irregularities (34% vs 15%, p less than 0.001) and early reocclusion (10% vs 1%, p less than 0.05) was higher in this group. However, when patients presenting with total occlusions were excluded from both groups primary angiographic success was similar (90% vs 91%) for groups I and II, respectively. We conclude that: 1) Lesions with intracoronary thrombus usually present other unfavourable angiographic characteristics for dilatation. 2) Results of coronary angioplasty in lesions with thrombus are similar to those obtained in other lesions when totally occluded vessels are excluded.

Angioplasty, Balloon, Coronary↗
PubMed1990

Electrocardiographic abnormalities and left ventricular systolic function in Chagas' heart disease.

In chagasic patients, the electrocardiogram becomes abnormal very late in the course of the disease. Most clinical studies concerning cardiac autonomic function of chagasic patients have been carried out in this very late stage of the disease. The purpose of this study was to assess accurately the left ventricular systolic function of chagasic patients with abnormal electrocardiograms. We performed left ventricular contrast cineangiography in 44 patients with positive complement fixation test for Chagas' disease and abnormal electrocardiograms. On the basis of the electrocardiographic abnormalities found in the electrocardiogram taken the night before the hemodynamic procedure, we divided our patients into three subgroups; those with rhythm disturbances, those with ventricular conduction abnormalities, and those with rhythm disturbances plus ventricular conduction abnormalities. The chagasic patients with only cardiac rhythm disturbances, had left ventricular volumes and ejection fractions which were similar to those of controls. On the other hand, the left ventricular volumes of the chagasic patients with ventricular conduction defects, although slightly larger, were still not different from those of controls. Finally, the chagasic patients, with cardiac rhythm disturbances and left ventricular conduction defects, had the largest left ventricular volumes (P less than 0.05), and the lowest ejection fractions (P less than 0.001) of all three subgroups. These findings clearly indicate that chagasic patients, in this very late stage of the disease, have a very variable degree of left ventricular systolic dysfunction. Furthermore, our results show a distinct tendency for the left ventricular volumes to increase, and for the ejection fraction to decrease; when the electrocardiogram becomes progressively more abnormal, and "mixed" electrocardiographic abnormalities appear.(ABSTRACT TRUNCATED AT 250 WORDS)

Adult↗
PubMed1990

Is there a role for lymph in intestinal glucose absorption?

Although the role of the lymphatic circulation in the uptake of dietary fat is well established, the absorption of water-soluble compounds, secreted by the enterocyte into the lymph, has received little attention. In the present study an estimate is made of the amount of dietary glucose that can be absorbed via the lymphatic system in the rat.

Animals↗