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Biomedical subjects

J M Torres

Publications and source records attributed to J M Torres.

At least 73 records · Page 4Linked to original sources
PubMed1991

Receptor-mediated endocytosis and recycling of alpha-fetoprotein in human B-lymphoma and T-leukemia cells.

The kinetics of iodinated human alpha-fetoprotein (AFP) binding and uptake by 2 human neoplastic lymphoid cell lines (CEM and RAJI) have been studied. Three saturation plateaus were obtained by incubating CEM and RAJI cells at 4 degrees C with 125I-AFP at different concentrations. Scatchard analysis suggested the presence of 3 types of receptor site with different affinities and capacities on cells of both lines. AFP binding was inhibited by unlabelled human and bovine AFP, and to a lesser extent by human serum albumin (SAH); no significant competition was observed with human transferrin (Tf) or ovalbumin (Ova). Pulse-chase experiments showed that 125I-AFP was released practically undegraded from the cells. Covalent conjugates of AFP and Tf with horseradish peroxidase (HRP) were used to follow the endocytosis and intracellular pathway of these serum proteins by electron microscopy. Both proteins were observed in coated vesicles, endosomes and a tubular vesicular network localized in the Golgi-centrosphere region. SAH-HRP was internalized to a much lesser extent. Ova-HRP was poorly internalized and was observed in lysosome-like organelles.

Binding, Competitive↗
PubMed1991

Changes in lipid composition of human peripheral blood lymphocytes infected by HIV.

The possible differences in lipid composition between human immunodeficiency virus- (HIV) infected and uninfected PHA-activated human peripheral blood mononuclear cells (PBMC) have been studied. The total fatty acid composition was similar, except for the proportion of arachidonic acid, that was slightly higher in infected than in noninfected cells. No significant differences were obtained in the incorporation of radiolabeled stearic or oleic acids in the different lipid classes. The staining of cells with Nile Red showed similar amounts of intracytoplasmic lipid droplets. On the contrary, the CH/PL ratio, the major factor in determining cell membrane fluidity, was clearly higher in infected than in uninfected cells (0.60 and 0.36, respectively). This fact is discussed in relation with the known high CH/PL ratio (0.95) of the lipid envelope of HIV.

Cholesterol↗
PubMed1991

[Characterization of collagen of canine intervertebral disks using the N-methyl-benzothiazol-2-on-hydrazone reaction].

Collagen types were studied in the lumbar intervertebral discs of non-chondrodystrophic dogs, 1 to 3 years old. Parts of intervertebral discs were frozen and sections were subjected to the 3-methyl-benzothiazol-2-on-hydrazone (MBTH) method, which permits differentiation of genetic types and maturation stages of collagen. The annulus fibrosus showed a blue (collagen I) and a violet colour (collagen II) at the external zone. The internal zone was more homogeneous and contained a mixture of both colours (collagen I and II). The nucleus pulposus showed only the violet colour, indicative of collagen II. Discs were also dissected at three different zones and submitted to an extraction technique to obtain collagen, then subjected to SDS-polyacrylamide gel electrophoresis and determination of spectrophotometric reactions of MBTH. Both studies demonstrated type I and type II collagens in the external and internal zones of the annulus fibrosus, but only type II in the nucleus pulposus. Collagen characterization, using this technique, would allow for evaluation in pathologic events of the intervertebral discs as well as for establishing the degree of alteration.

Animals↗
PubMed1990

Quantification of alpha-fetoprotein and transferrin endocytosis by lymphoid cells using flow cytometry.

Alpha-fetoprotein (AFP) and transferrin (Tf) are serum proteins actively internalized by many growing cells through specific cell surface receptors. The intracellular pathways of AFP and Tf are very similar: both proteins enter the cells via coated pits and receptosomes, move to tubular elements of the transreticular portion of the Golgi and are recycled back to the cell surface and extracellular medium in native form. In the present work, the capacity of human lymphoid cells to bind AFP and Tf at 4 degrees C and to endocytose them at 37 degrees C was quantified by flow cytometry analysis on a FACS 440 using fluoresceinated derivatives of these proteins. The results obtained show that binding and internalization of AFP and Tf by lymphoid cells are saturable processes at either 4 degrees C or 37 degrees C. The method developed permits direct quantitative measurement of molecules bound to the cell surface or present within the cell.

Cell Line↗
PubMed1990

Cytotoxicity of chlorambucil and chlorambucil-fatty acid conjugates against human lymphomas and normal human peripheral blood lymphocytes.

The cytotoxic activity of chlorambucil (Chl) and of chlorambucil-fatty acid conjugates of different degree of unsaturation have been assayed in vitro upon two human lymphoma cell lines and comparatively, upon quiescent and mitogen-activated lymphocytes from healthy blood donors. The cell toxicity observed with Chl-arachidonic acid and Chl-docosahexaenoic acid against lymphoma cells was, at any experimental condition used, equal or higher than the individual toxic potential of either chlorambucil or fatty acids. The two conjugates, like chlorambucil alone, were toxic against mitogen-activated lymphocytes. Contrary to chlorambucil, Chl-arachidonic at any concentration tested, lacked of toxicity towards normal non-activated lymphocytes. Chl-oleic acid conjugate was, whatever the cell species tested, much less toxic than Chl alone. In conclusion, the coupling of chlorambucil with polyunsaturated fatty acids increases: (a) the selectivity against neoplastic versus quiescent lymphocytes and (b) the toxicity for B-lymphoma cells. The selective effect of Chl-fatty acid conjugates is discussed in relation with the expression of an AFP/AFP-receptor autocrine system in malignant lymphoblastoid cells and in mitogen-activated lymphocytes.

Arachidonic Acids↗
PubMed1990

[Immunogenicity and long-term effectiveness of the hepatitis B vaccine in newborns from HBsAg-positive mothers].

We have followed up until age 2 years 25 infants who had received the hepatitis B vaccine to prevent being infected from their mothers who were HBsAg carriers. All had developed antibodies. At 2 years of age, 24% of infants had antiHBsAg titers lower than 10 mU/ml. The geometric mean of antiHBsAg titer in those infants who had received plasma derived vaccine was 660 mU/ml and in those having received recombinant vaccine was 903 mU/ml. HBsAg was negative in all the studied samples. In two infants positive antiHBc were detected.

Carrier State↗
PubMed1990

Fatty acid metabolism in human lymphocytes. I. Time-course changes in fatty acid composition and membrane fluidity during blastic transformation of peripheral blood lymphocytes.

The time-course changes in fatty acid composition of human T-lymphocytes during blastic transformation were analysed, as well as the variations in membrane fluidity determined by fluorescence polarization of 1,6-diphenyl-1,3,5-hexatriene (DPH), using a fluorescence-activated cell sorter. The more important changes observed, in activated relative to quiescent cells, started after 24 h and consisted in an increase in the proportion of oleic (18:1(n - 9)), docosapentaenoic (22:5(n - 3)) and docosahexaenoic (22:6(n - 3)) acids and a decrease in that of linoleic (18:2(n - 6)) and arachidonic (20:4(n - 6)) acids. This represented a relative increase of 26% for 18:1, 56% for 22:5 and 84% for 22:6 in peripheral blood mononuclear cells (PBMC) and 35%, 182% and 94%, respectively, in purified T-lymphocytes, both activated for 72 h. The decrease in n - 6 fatty acids was of 42% for 18:2 and 14% for 20:4 in PBMC and 30% and 19%, respectively, for 72 h. The decrease in n - 6 fatty acids was of 42% for 18:2 and 14% for 20:4 in PBMC and 30% and phosphatidylethanolamine) rather than neutral lipids. The 18:1/18:0 ratio increased greatly in major cell phospholipids. The proportion of 20:4, 22:5 and 22:6 in phosphatidylinositol was not significantly altered after 72 h of activation. The molar ratio cholesterol/phospholipids was reduced in 72-h-activated lymphocytes (0.29) compared to quiescent cells (0.5). On the other hand, the stimulation of human T-lymphocytes caused a significant decrease in the order parameter (S) of DPH, according to the observed changes in lipid composition. After 72 h in culture, the S value for quiescent and stimulated T-lymphocytes was 0.530 and 0.326, respectively. In conclusion, the blastic transformation of human T-lymphocytes is associated with changes in lipid composition which modify the physical properties of their membranes. These modifications could modulate, in turn, the activity of membrane proteins implicated in the process of blastic transformation.

Cells, Cultured↗
PubMed1990

Defective uptake of alpha-fetoprotein (AFP) and transferrin (Tf) by PHA-activated peripheral blood lymphocytes from patients with AIDS and related syndromes.

Serum alpha-fetoprotein (AFP) and transferrin (Tf) are actively endocytosed by many growing cells during ontogenic and neoplastic growth, but also by peripheral T lymphocytes upon mitogen activation. AFP and Tf uptake occurs through receptor-mediated endocytosis. The purpose of the present work was to assess whether the expression and functional activity of AFP and Tf receptors are impaired in mitogen-activated T cells from several groups of HIV-1 seropositive (HIV+) individuals. Forty HIV+ cases were studied, including 12 patients with AIDS, 12 with lymphoadenopathy syndrome (LAS), as well as 16 asymptomatic homosexuals (As). Quantification of AFP and Tf uptake was carried out by fluorescence-activated cell sorting (FACS) using fluoresceinated derivatives of these proteins. Compared with healthy blood donors, the three HIV-1 seropositive groups exhibited clear impairment in the ability of their peripheral blood mononuclear cells (PBMC) to internalize AFP and Tf. The decrease in mean values of AFP uptake correlates roughly with the severity of the clinical status. Although these observations need to be confirmed after a much wider study groups, the AFP-Tf-endocytosis assay presented here clearly reveals early defective functions of mitogen-responsive T cells in disease-free subjects and may provide the basis for a prognostic test. The pathophysiological implications of these facts are discussed in relation to the structural and/or metabolic activities of fatty acids and iron, the ligands carried by AFP and Tf, respectively.

AIDS-Related Complex↗
PubMed1989

[Incidence of nosocomial infections. Comparison of 2 surveillance systems: clinical vs microbiological follow-up].

The effectiveness of a clinical and a microbiological follow-up systems for the detection of hospital-acquired infection (HI), both independently and simultaneously applied, were prospectively evaluated. The observed incidence rate was 11.4%. The clinical follow-up detected 81.3% of HI while microbiological follow-up detected 59.7%. This difference was statistically significant (p less than 0.001). It took 43 and 45 minutes to detect each instance of HI with the clinical and microbiological methods, respectively. Clinical methods are the most adequate to obtain maximal sensitivity in the overall surveillance of hospital-acquired infection, whereas microbiological follow-up may be useful for the detection of some types of HI such as bacteremia or urinary tract infection.

Cohort Studies↗
PubMed1989

Alpha-fetoprotein gene expression in human lymphoblastoid cells and in PHA-stimulated normal T-lymphocytes.

Alpha-fetoprotein (AFP) is mainly synthesized by the fetal liver, the yolk sac and, to a much lower extent, by a few non-hepatic fetal tissues (i.e. kidney, pancreas, lung). This property is considered to be lost in mature quiescent cells of the adult. In the present we have studied the expression of AFP mRNA sequences in phytohemagglutinin (PHA)-stimulated normal human T-lymphocytes and in several human lymphoma cell lines. The amount of mRNA transcripts detected in quiescent T-lymphocytes by dot and Northern blot analysis was very low. It increased rapidly after PHA-activation, reached a maximum at 72 hours (six fold the level observed for quiescent T-lymphocytes) and decreased thereafter. The lymphoma cell lines Daudi, Raji, Rh6 et CEM, all expressed elevated levels of AFP mRNA. The transcripts had the size expected for human AFP, suggesting that they were functional and probably translated into protein. The possible role of AFP synthesis in lymphocyte blastogenesis and in lymphoma growth is discussed in relation with the strong binding affinity of this protein for polyunsaturated fatty acids.

DNA Probes↗
PubMed1989

Expression of alpha-fetoprotein receptors by human T-lymphocytes during blastic transformation.

Alpha-fetoprotein (AFP) and transferrin (Tf) are actively internalized by many growing cells during ontogenic and neoplastic development, including human malignant T- and B-lymphoblastoid cells. Their internalization is, on the contrary, greatly diminished or absent in mature, non-proliferating elements. In the present work, peripheral blood mononuclear cells (PBMCs) and T-lymphocytes, harvested from normal human donors, were induced to blastic transformation with phytohemagglutinin (PHA) and their ability to uptake AFP and Tf was measured and compared with Tf uptake in the same conditions. The capacity of the cells to internalize both proteins was quantified by fluorescence activated cell sorter (FACS) using fluoresceinated derivatives of these proteins. The results obtained show a significant uptake of AFP by T-lymphocytes upon PHA stimulation. The values of AFP incorporation were similar for all the cells studied (PBMCs, T-cells and T4, T8 cell subsets). The time course of AFP uptake paralleled, under the same conditions, the uptake of Tf and the expression of IL2 receptors. AFP uptake increased rapidly from the zero time (resting T-cells) and reached a maximum around 72 hr after PHA activation. Scatchard analysis of kinetic data at 4 degrees C revealed for Hu-AFP one single group of specific binding sites in PHA activated T-lymphocytes with a dissociation constant of 3.03 x 10(-7) M and around 88,000 sites/cell. There results strongly suggest the transitory expression of AFP receptors in T-lymphocytes during blastic transformation.

Cells, Cultured↗
PubMed1989

Mediastinal, left, and right atrial pressure variations with different modes of mechanical and spontaneous ventilation.

Variations in mediastinal, left, and right atrial pressures (MedP, LAP, RAP, respectively) were measured by means of catheters and tubes positioned in ten patients with nonvalvular cardiac surgery. For each pressure, a maximum, minimum, and mean value was determined in relation to its oscillations during the respiratory cycle. Thus, we compared the variations in MedP, LAP, and RAP in controlled mechanical ventilation (CMV), CMV with 5 cm H2O PEEP, synchronous intermittent mandatory ventilation (SIMV), SIMV with 5 cm H2O PEEP, continuous positive airway pressure (CPAP), and spontaneous respiration (SR). We built an experimental model to compare the measurements obtained by air-filled tubes inserted at surgery with those obtained by esophageal balloons filled with water. The maximum MedP did not vary significantly in these patients except when SIMV and SR were compared; however, the minimum MedP diminished significantly (p less than .001) in SIMV, SIMV-PEEP, CPAP, and SR, with negative inspiratory values reaching significant proportions. The mean values of MedP, LAP, and RAP showed a similar tendency although to a lesser degree. The experimental model revealed a strong linear relation between the values obtained with air-filled tubes and those obtained with water-filled esophageal balloons (r = .99, p less than .001). These results suggest that the mean values of MedP, LAP, and RAP do not reflect the dynamic variations in ventricular filling pressure accurately, nor the important negative inspiratory peaks that appear in different types of ventilation using spontaneous cycles with and without PEEP. These inspiratory peaks can overload the left ventricle by hydrostatic gradients, and lead to pulmonary edema in susceptible patients.(ABSTRACT TRUNCATED AT 250 WORDS)

Adult↗
PubMed1989

Morphological characterization of the pathway of endocytosis and intracellular processing of transferrin and alpha-fetoprotein in human T lymphocytes stimulated with phytohemagglutinin (PHA).

Covalent conjugates of transferrin (Tf) and alpha-fetoprotein (AFP) with horseradish peroxidase (HRP) have been used to follow, at the ultrastructural level, the uptake and the intracellular pathway of these proteins in peripheral blood human lymphocytes stimulated by phytohemagglutinin (PHA) to blast formation. Both proteins enter specifically the cells via vesicles (60-70 nm in diameter) and endosomes. They are then observed in multivesicular bodies and tubular vesicular elements in the Golgi region. AFP is thus found in the same subcellular compartments as Tf and is probably also recycled, as most of the 125I-labeled protein leaves the cells undegraded. Unstimulated lymphocytes do not internalize significantly AFP-HRP. The uptake of a noncovalent conjugate of AFP-HRP and [3H]-arachidonic acid [3H-(20:4)] is usually poor, at 37 degrees C, in unstimulated lymphocytes as well as, at 4 degrees C, in lymphocytes stimulated for 72 h. Stimulated lymphocytes incubated at 37 degrees C with the radioactive conjugate show a heavy labeling of cell organelles and more particularly of lipid droplets. AFP could regulate the intracellular delivery of fatty acid molecules.

Endocytosis↗
PubMed1989

[Epidemiologic and therapeutic aspects of bacteremic infections of the urinary tract].

A survey was carried out of all urinary tract infections which developed bacteremia during an 18 month period. The number of episodes of bacteremia of urinary origin (BUO) detected in our institution during that period was 108. The urinary tract was the most common origin of the cases of community acquired (CA) bacteremia and the third in the hospital acquired (HA) cases. In both types, the most frequent organism was E. coli (69.6% and 40%, respectively). The most common underlying diseases were diabetes mellitus (25.7%) and neoplasia (20%); nephrourologic disorders of some type were present in 29.6% of cases. In 81% of HA episodes there were urinary catheters as risk factors. In the CA bacteremias, the gram-negative bacilli except Pseudomonas aeruginosa had a 100% sensitivity to aminoglycosides. Sensitivity to first generation cephalosporins was detected in 81% of the E. coli and in 100% of the Klebsiella spp strains. In HA cases, amikacin (100% of E. coli, Pseudomonas, Klebsiella and Proteus) and cefotaxime (except Pseudomonas) were the antibiotics to which the highest rates of sensitivity were found. Overall mortality rate of BUO was 16.6% (13.6% for CA and 21.5% for HA); in 6% and 5% of cases, respectively, death was directly associated with bacteremia.

Cross Infection↗
PubMed1987

Glutathione status and sensitivity to GSH-reacting compounds of Escherichia coli strains deficient in glutathione metabolism and/or catalase activity.

The intracellular concentrations of total glutathione, GSSG and protein X S-SG, the total excreted glutathione concentration, and the susceptibility towards GSH-reacting compounds were assayed in strains of Escherichia coli deficient in biosynthesis and/or reduction of glutathione. A deficiency in glutathione reductase displaced the glutathione status towards the oxidized forms. This displacement was more clearly appreciated in strains additionally deficient in glutathione biosynthesis. A deficiency in catalase activity also produced an increase in the oxidation of glutathione. The most severe changes were observed in the concentrations of protein-glutathione mixed disulfides and in the amount of glutathione excreted to the medium. Increased sensitivities towards compounds known to interact with cellular GSH were observed in glutathione reductase deficient strains, although these effects were enhanced in strains additionally deficient in GSH biosynthesis.

Catalase↗