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Biomedical subjects

A R Torres

Publications and source records attributed to A R Torres.

49 records · Page 3Linked to original sources
PubMed1983

Ion-exchange displacement chromatography of proteins, using narrow-range carboxymethyldextrans and a new index of affinity.

A new method of characterizing carboxymethyldextrans with respect to their relative affinities for an anion exchanger can be applied not only to pure preparations but also to fractions of a displacement chromatogram in which these polyanions have been used as spacers. This, along with the development of a means of preparing carboxymethyldextrans with narrow ranges of affinity, as contrasted with the very heterogeneous preparations previously used, has greatly facilitated the focusing of resolving power on critical regions of the chromatogram. The effectiveness of this approach is illustrated by the separation of proteins that differ only slightly in affinity, using the genetic variants of beta-lactoglobulin as one model and the numerous components of purified ovalbumin as another.

Chemical Phenomena↗
PubMed1982

Solubilization of nonhistone chromosomal proteins by carboxymethyldextran for chromatography.

Chromosomal proteins extracted from calf thymus by 0.35 M NaCl were insoluble at the low salt concentration needed initially for ion-exchange chromatography. However, the addition of high-affinity carboxymethyl-dextran rendered the precipitated proteins soluble, permitting them to be fractionated by elution from DEAE-Sephacel. In this way, the separation of HMG-1 from HMG-2 was achieved, as well as a partial fractionation of the low mobility group proteins, under conditions that did not disturb the native conformation of the proteins.

Animals↗
PubMed1982

Two-dimensional gel electrophoresis can be used to examine chromatographic effluent fractions from displacement column chromatography.

We show how two-dimensional gel electrophoresis can be used to monitor protein components in effluent fractions from a displacement column. A minor protein in human serum, of interest in studies on psoriasis and highly enriched by using carboxymethyldextrans as displacers on DEAE-Sephacel, was easily detected in the effluent fractions with the two-dimensional gel method because its concentration was sufficiently high and there was no interference by the carboxymethyldextrans or salt.

Blood Proteins↗
PubMed1982

A role for humoral factors in psoriasis.

Because a large body of evidence suggests that the presence of circulating humoral factors could play a role in the induction/maintenance/resolution of psoriasis and because few investigators have explored their potential, we elected to conduct a survey analysis of the effects of the noncellular component of blood, serum, from normal and psoriatic subjects on assays of the inflammatory/immune system and on cell proliferation. Sera from psoriatic subjects are less chemotactic for monocytes than normal; this does not appear to be secondary to excess inhibitors for the chemoattractants, ZAS and bacterial factor. Preincubation of monocytes in psoriasis sera and normal sera results in an equal degree of inhibition of subsequent chemotaxis by monocytes. Relative to media alone, both normal and psoriasis sera equally inhibit DNA synthesis of HeLa cells. The addition of psoriasis sera to mitogenically stimulated lymphocytes will selectively suppress the blastogenic response in comparison to normal sera. These differences prompted a 2-d gel electrophoresis analysis of sera of psoriatic subjects. Specific differences are noted in the group of proteins migrating in the area of alpha 1 antitrypsin. These findings suggest that the noncellular component of the humoral system must also be factored into considerations of the etiopathology of psoriasis.

Blood Protein Electrophoresis↗
PubMed1979

Fractionation of granule proteins of granulocytes by copper chelate chromatography.

The tendency of lactoferrin to associate with other proteins at low salt concentrations defeated attempts to fractionate the acetate-extracted granule proteins of guinea pig granulocytes by ion-exchange chromatography. This problem was overcome by using copper-chelate chromatography at high salt concentrations to separate lactoferrin from the other granule proteins. Lysozyme and a 'cationic protein' were purified to apparent homogeneity in the same operation. The chromatographic profile of proteins extracted from purified secondary granules differed from that of proteins extracted from total granules chiefly in the absence of a substantial 'cationic protein' peak.

Animals↗
PubMed1979

Displacement chromatography of simple protein mixtures, using carboxymethyldextrans.

Simple mixtures of proteins have been used as models to demonstrate that the fractionation of proteins by carboxymethyldextrans on an anion exchanger (Peterson, E.A. (1978) Anal. Biochem. 90, 767--784) is fundamentally a displacement process. Examples include the separation of two closely similar proteins, the A and B forms of beta-lactoglobulin. The use of carboxymethyldextran spacers was essential for good separation, since resolution based on protein--protein displacement was generally inadequate. The origins and effects of heterogeneity in the preparations used as spacers are discussed.

Anion Exchange Resins↗
PubMed1979

Regulation of surface topography of mouse peritoneal cells. Formation of microvilli and vesiculated pits on omental mesothelial cells by serum and other proteins.

The mesothelial cells of the mouse omentum provide an in vivo model for the study of the mobilization of labile microvilli on the cell surface. These mesothelial cells are sparsely covered with microvilli and large pits 150--400 nm in diameter, termed vesiculated pits. On the unstimulated cell, the microvilli average 44/100 microns2 and pits, 30/100 microns 2 of surface and they are rapidly induced to increase in number by the intraperitoneal injection of isologous mouse serum. After 2 min, microvilli increase threefold, continue to sevenfold at 30 min, and decrease to fourfold at 90 min. Vesiculated pits increased with similar kinetics. Bovine serum albumin and gamma globulin also stimulate the microvilli and pits to form, but the response is a slow, gradual rise to five- or sixfold the normal value at 90 min. Evidence indicates that multiple factors, possibly including insulin and immunoglobulins, are involved in the effect of serum. The close physical and temporal relationship between microvilli and pits suggests that a correlation exists in their mobilization by the cell and it is hypothesized that microvilli function in the regulation of the cortical microfilament network in effecting this mobilization.

Animals↗
PubMed1979

Effect of inflammatory serum on 14C-glucosamine incorporation into bone marrow granulocytes in vitro.

As a preliminary approach to developing a biochemical assay for detecting humoral regulators of granulocyte maturation in the normal and inflammatory states, studies were carried out on the effects of normal and inflammatory sera on the incorporation of 14C-glucosamine into the glycoproteins of bone marrow granulocytes in vitro. We observed that, relative to normal serum, inflammatory serum had a marked stimulatory effect on 14C-glucosamine incorporation into these glycoproteins. This property of inflammatory serum reached a maximum at about 8 h after the initiation of inflammation in vivo and preceded the maximum increase in the mitotic activity of granulocyte precursors in the marrow by 18 h. It was also found that normal serum contains both dialyzable and heat-sensitive nondialyzable factors that inhibit 14C-glucosamine incorporation into bone marrow granulocytes in vitro. Data are presented which indicate that the stimulatory effect of inflammatory serum is most likely due to a nondialyzable factor which is capable of blocking the effect of the inhibitors present in normal serum.

Animals↗