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J Rivera

Publications and source records attributed to J Rivera.

At least 235 records · Page 13Linked to original sources
PubMed1986

Recycling of receptor-bound IgE by rat basophilic leukemia cells.

Rat basophilic leukemia (RBL) cells have receptors for immunoglobulin E (IgE). We previously showed that unlike some other ligands, the binding of monomeric rat or mouse IgE to RBL cells does not induce endocytosis. However, aggregation of the cell-bound, monomeric mouse IgE anti-dinitrophenyl (DNP) with DNP-protein conjugates leads to endocytosis of the aggregated mouse IgE and to the co-endocytosis of some unaggregated monomeric rat IgE. In this study we analyzed and compared the fate of co-endocytosed and endocytosed IgE. We found that co-endocytosed rat IgE recycled back to the cell surface within 3 to 4 hr. In contrast, endocytosed, immunochemically cross-linked, receptor-bound mouse IgE anti-DNP was partially degraded and was released into the medium, with no observable recycling of receptors, by 3 hr. However, addition of the hapten, DNP-lysine, resulted in rapid recycling (t1/2 10 min) of the endocytosed receptor-bound IgE to the plasma membrane and blocked additional endocytosis. Recycling of the endocytosed mouse IgE was more pronounced when the hapten was added to cells within 20 min of the initiation of endocytosis. When the hapten was added to the cells at later times (60 to 180 min), progressively less IgE recycled to the surface. This may reflect shuttling of the internalized IgE from a 'prelysosomal' to a 'lysosomal' compartment. Thus we provide evidence for recycling of monomeric IgE receptor complexes, sorting between cross-linked and non-cross-linked IgE receptor complexes, the freeing of receptor-bound monomeric IgE from the endocytosed immune-complexed IgE, and the apparent dependence of the recycling efficiency upon intracellular localization.

Animals↗
PubMed1986

Fate of atrazine and trifluralin from an industrial waste dumping at the Llobregat River. Presence in fish, raw and finished water.

Analysis carried out after fish mortality in an industrial area in the neighbourhood of the Llobregat River, water supplier for Barcelona and its area, led us to identify two herbicides (atrazine and trifluralin) in the wastewaters from an industrial sewage where, among other factories one at least, is devoted to pesticide manufacturing. The fate of these herbicides is followed in fish (dorsal muscle), raw water entering the water works plant and tap water. Analyses by GC, GC/MS/DS and mass fragmentography were routinely employed.

Animals↗
PubMed1986

Endocytosis of aggregated immunoglobulin G by rat basophilic leukemia cells; rate, extent, and effects on the endocytosis of immunoglobulin E.

Rat basophilic leukemia (RBL) cells have distinct receptors for IgE and IgG. We assessed the endocytosis of chemically and immunochemically cross-linked mouse-IgG and its influence on the simultaneous endocytosis of IgE. We found that at 37 degrees C, aggregates of IgG and IgE were endocytosed at about the same rate with one-half of the maximal endocytosis occurring in 5 to 13 min, and the efficiency of endocytosis for both ligands ranging from 40 to 70%. We also found that endocytosis of cross-linked IgE and IgG occurred simultaneously and neither ligand significantly affected the rate or extent of endocytosis of the other. The cells accumulated the cross-linked IgG, and then released it to the extracellular environment, at a rate (less than 3%/hr) slower than the released endocytosed IgE (greater than 10%/hr). Using an assay that discriminates between unbound and receptor-bound oligomeric IgG, we found that oligomeric IgG is endocytosed with its receptor, and that the bulk of the ligand remains bound to its receptor for greater than 120 min after endocytosis. The differences in the rate of release of endocytosed IgG vs IgE suggests that the intracellular fate or pathway of these two oligomeric ligands may differ.

Animals↗
PubMed1986

Comparative evaluation of the effect of pharmacological agents on endocytosis and coendocytosis of IgE by rat basophilic leukaemia cells.

The aggregation of IgE bound to rat basophilic leukaemia (RBL) cells leads to the exocytosis of mediators, the endocytosis of the antigen-aggregated mouse IgE anti-DNP, as well as the coendocytosis of some unaggregated monomeric rat IgE (IR162) and/or unbound receptors. We describe here the relative effect on endocytosis and coendocytosis of various pharmacological agents that block or enhance exocytosis. We have previously shown that, unlike exocytosis, endocytosis by RBL and normal rat mast cells was independent of extracellular calcium. We show here that the presence of calcium chelators or antagonists also had no effect on endocytosis of cross-linked IgE. However, coendocytosis of non-cross-linked IgE was partially inhibited by the elimination of extracellular calcium and the addition of calcium chelators such as EDTA or EGTA-Mg2+. Moreover, the addition of calcium antagonists such as Ni2+ and Co2+ (5 mM) to an incubation mixture containing Ca2+ (1 mM) resulted in the complete inhibition of coendocytosis without affecting endocytosis. Other inhibitors of exocytosis such as sodium azide (10-2M), quercetin (10-4M) and dibutyryl cyclic AMP (10-2 M) blocked coendocytosis completely but had no effect on endocytosis. Sodium azide (10 mM) in combination with 2-deoxyglucose (10 mM) effectively inhibited (90%) endocytosis. Cytochalasin B (10-4 M), which was shown to enhance serotonin release, had no effect on the extent of endocytosis or coendocytosis observed 20 min after the initiation of aggregation. Thus, in RBL cells, endocytosis, coendocytosis and exocytosis exhibit distinguishable sensitivities to some pharmacological drugs.

Animals↗
PubMed1985

The receptor for immunoglobulin E on rat basophilic leukemia cells: effect of ligand binding on receptor expression.

We have evaluated the effect of ligand binding on expression of the receptor for IgE on rat basophilic leukemia (RBL) cells. RBL cells were grown in the presence or absence of 131I-labeled IgE and sometimes were also surface labeled with 125I. We found that cells grown in the presence of IgE continued to accumulate receptors at the surface and thus the apparent amount of cell-associated IgE continued to increase. The results obtained suggest that, in the presence of IgE, the elimination of the receptor from the surface was halted or slowed significantly (approximately equal to 80%) while insertion into the membrane of previously synthesized receptor continued.

Animals↗
PubMed1985

The fate of IgE bound to rat basophilic leukemia cells. IV. Functional association between the receptors for IgE.

Rat basophilic leukemia cells (RBL-2H3) have receptors for immunoglobulin E (IgE) and immunoglobulin G (IgG). These receptors for IgE mediate the endocytosis of chemically or immunochemically cross-linked IgE but not monomeric IgE. However, unoccupied receptors were endocytosed with cross-linked IgE. To further assess the degree and specificity of the observed coendocytosis, we exposed cells carrying monomeric rat IgE and monomeric mouse IgE anti-DNP to a DNP-protein conjugate. We found that up to 30% of the surface-bound monomeric rat IgE redistributed at 0 to 4 degrees C and was then internalized at 37 degrees C with the immunochemically cross-linked mouse IgE. To assess the specificity of the coendocytosis, we exposed cells carrying monomeric rat IgE to immunochemically cross-linked mouse IgG. We found that the binding, patching, and endocytosis of cross-linked mouse IgG had no effect on the monomerically bound rat IgE. The rate of coendocytosis was the same as the rate of endocytosis (t 1/2 3 to 5 min). The extent of coendocytosis depended on the extent of endocytosis but was relatively insensitive to changes in the ratio between mouse and rat IgE over a broad range. These results indicate that some of the receptors for IgE are associated in a specific fashion.

Animals↗
PubMed1985

[Differentiation of the nutritional status of preschool children, according to socioeconomic levels, in a marginal zone].

This article informs of a study carried out in an attempt to validate a new methodology to differentiate socioeconomic levels in a low income urban population group, as well as to correlate each level with the degree of malnutrition of preschool children, using the Gómez and Waterlow classifications. The socioeconomic indicators selected were: housing, main occupational activity and educational level of the head of the family, number of members per room, food expenditure per capita, per week, and ownership of a few household articles. A scale was constructed on the basis of the afore-mentioned indicators, and values were assigned on a point system, resulting in three levels: high, medium and low. Weight and height were determined in preschool children. In order to establish correlation of anthropometric data with socioeconomic levels, and to determine if such levels permitted to differentiate the degree of malnutrition, two types of nutritional classifications were used. Of the total of 187 families selected, 46 were evaluated as of high level, 72 medium and 69, low. Analysis of the weight-for-age and weight-for-height in children 24 to 47 months of age, and total preschool children, that is, from 12 to 59 months, revealed significant differences in both classifications, p less than 0.001. The authors conclude that the point scale applied to determine socioeconomic levels, was sufficiently sensitive in distinguishing the degree of malnutrition in preschool children, especially when analyzing the total population; though not significant in a few age groups, this was probably due to the reduced number of same. It is recommended that the Gómez classification be used permanently, particularly in cross-sectional surveys, and the Waterlow classification, because of its rapid diffusion in the world.

Body Height↗
PubMed1985

Political orientation and occupational values of college youth, 1969 and 1981: a shift toward uniformity.

McFalls and Gallagher (1979) have found a strong relationship between the occupational values and political orientations of college students. Their study was based on the results of a sample survey conducted in 1969. However, the political climate on college campuses has changed dramatically, and so has the nature of the job market. A new survey was conducted in 1981 which was identical to the 1969 survey. Its objective was to determine if the same political group differentials in occupational values which existed in the politically tumultuous late sixties and early seventies still hold in the more placid 1980s. The findings are reported here.

Achievement↗
PubMed1984

The behavior of the solubilized receptor for immunoglobulin E in polyethylene glycol-detergent solutions: characterization and potential applications.

We studied the effect of polyethylene glycol (PEG) on the solubility of the receptor for immunoglobulin E (IgE) in non-ionic detergent extracts of rat basophilic leukemia (RBL) cells. We found that the precipitation patterns of free and IgE-bound receptor were identical but differed from that of unbound IgE. Thus, 85 to 95% of the free receptor and the IgE-receptor complexes precipitated at 13% PEG in the presence of 0.5% Nonidet P-40, whereas 95% of the unbound IgE remained soluble. A similar degree of differentiation between the precipitation of receptor-bound and unbound IgE was found when we used extracts and PEG solutions prepared with several non-ionic and/or neutral detergents. The intact IgE-receptor complex with the full complement of subunits (alpha, beta, gamma) precipitated more efficiently than the IgE-alpha-chain-complex. The presence of phospholipids, which were previously shown to be important for preservation of the association between the receptor subunits, enhanced the efficiency of precipitation of the IgE-receptor complex. The presence of PEG also had an effect on the solubility of cellular phospholipids and some of the detergents, although the effect of PEG on either could not be directly related to its effect on the solubility of the IgE-receptor complex. The radioiodinated receptor for IgE, much like other radioiodinated RBL cell membrane proteins, was soluble (greater than or equal to 95%) at approximately 7% PEG but could be specifically and efficiently precipitated from crude cell extracts, in the presence of 7% PEG upon the addition of anti-receptor immunoglobulins alone. Using mouse anti-dinitrophenyl IgE antibody, we found that unlike unbound antigen (DNP-BGG) or the IgE-receptor complex, the detergent-solubilized DNP-BGG-IgE-receptor complex was insoluble at 7% PEG. Consequently, PEG can be employed in assays to quantitate the soluble receptor, and to immunoprecipitate it specifically and directly. Moreover, the use of PEG can facilitate the distinction between unbound antigen and antigen-IgE-receptor complex as well as between the latter and IgE-receptor complex.

Animals↗
PubMed1984

The fate of IgE bound to rat basophilic leukemia cells. III. Relationship between antigen-induced endocytosis and serotonin release.

We have previously shown that, unlike monomeric IgE, chemically derived dimers, trimers, and heavier oligomers of IgE were internalized efficiently. This finding suggested that endocytosis, like mediator release, is triggered by cross-linking of the cell surface receptors for IgE. In the present study, we analyzed the temporal and functional relationships between the two events. We used rat basophilic leukemia cells (RBL-HR+-2H3) and rat peritoneal mast cells, which were allowed to bind monomeric 125I mouse IgE hybridoma anti-dinitrophenyl (HI-DNP-E-26-82), and the polyvalent antigen 131I-dinitrophenylated human serum albumin (DNP15-HSA). We found that at 37 degrees C, 50% of the cell surface-bound immune complexes were internalized rapidly (t1/2 3 to 5 min) by RBL-HR+-2H3 cells with only minimal reduction (1/3) in the extent of internalization when very few of the receptors (approximately 5%) were saturated with IgE. Normal mast cells internalized cell surface-bound immune complexes at a similar rate (t1/2 4 to 5 min). Unlike serotonin release, internalization was independent of extracellular calcium and continued to increase as the ratio of DNP15-HSA to IgE increased 10- to 100-fold over the ratio required for optimal histamine release. In the RBL cells, internalization preceded serotonin release, reaching a peak at about 10 min, while the release (t1/2 13 to 19 min) continued for up to 60 min. Presumably, some of the cross-linked IgE internalized less effectively and continued to trigger serotonin release. The reverse relationship between the rates of internalization and release (t1/2 less than 1 min) was found in normal rat mast cells. We conclude that although cross-linking of two or more receptors triggered both endocytosis and exocytosis, the two events are not necessarily sequential.

Animals↗
PubMed1983

The fate of IgE bound to rat basophilic leukemia cells. II. Endocytosis of IgE oligomers and effect on receptor turnover.

We have assessed the internalization of variously sized oligomers of IgE bound to rat basophilic leukemia (RBL) cells by measuring their accessibility to the extracellular environment, and by direct visualization of the radiolabeled ligands. We also followed the fate of the internalized ligands and their receptors, as well as the fate of the free receptor on cells internalizing oligomers. In contrast to monomeric IgE, surface-bound oligomeric IgE was internalized. Notably, dimers provided an effective signal for internalization, although larger oligomers seem to be internalized more efficiently. In our experiments, 48% of the cell-bound dimers and 67% of the trimers were eliminated from the cell surface in 180 min. One-half of the maximal internalization observed with dimers and trimers occurred in 25 and 11 min, respectively. Release of radioactivity into the supernatant followed internalization; the released radioactivity did not bind to fresh cells and was only partially TCA-precipitable. Radioactive ligands remaining associated with the cells were unchanged as judged by m.w; they also were shown to remain receptor-bound. During either internalization or release of substantial amounts of the originally cell-bound oligomers, there was no increase in IgE-binding activity. In contrast, there was a transient drop (25%) in the number of free surface receptors suggesting internalization of the free receptors together with the oligomer-occupied receptor. Cells that failed to release histamine (RBL-I) processed dimeric and trimeric IgE similarly to histamine-releasing (RBL-2H3) cells. We conclude that dimeric and trimeric IgE are internalized by RBL cells and later are released to the medium in a partially degraded form. The ligand-bound receptor seems to be internalized with the ligand, along with some free receptor, and does not appear to be reusable or to recycle rapidly to the cell surface.

Animals↗