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Biomedical subjects

A Rothstein

Publications and source records attributed to A Rothstein.

At least 91 records · Page 5Linked to original sources
PubMed1981

The sulfhydryl groups of the 35,000-dalton C-terminal segment of band 3 are located in a 9000-dalton fragment produced by chymotrypsin treatment of red cell ghosts.

Five sulfhydryl groups of band 3, the anion-transport protein of the red blood cell membrane, can be labeled by N-ethylmaleimide (NEM). Two of these are located in a 35,000-dalton, C-terminal segment produced by chymotrypsin treatment of cells. Extensive treatment of unsealed ghosts with chymotrypsin results in the disappearance of the 35,000-dalton segment, but its two NEM-binding sites area preserved in a 9000-dalton peptide. The latter must therefore be a proteolytic product of the larger segment. Labeling of sulfhydryl groups of band 3 by an impermeant analog of NEM occurs in inside-out, but not in right-side-out vesicles derived from red cell ghosts, supporting the conclusion that NEM-reactive sulfhydryl groups, including those in the 35,000- and 9000-dalton segments, are exposed at the cytoplasmic face of the membrane. These findings support the conclusion that the 35,000-dalton segment crosses the bilayer, and suggest that the 9000-dalton segment may be a membrane-crossing portion of the 35,000-dalton segment.

Anion Exchange Protein 1, Erythrocyte↗
PubMed1981

Mercurials and red cell membranes.

Mercurials influence a large number of protein-mediated functions in membranes including transport phenomena, related enzyme activities and sructural factors such as deformability and phospholipid asymmetry. The sulfhydryl groups that are the targets for mercurials are found in different locations in the membrane, the outer surface, internal compartments, or cytoplasmic surface. Those on the outer surface are immediately influenced even by non-penetrating mercurials, whereas those within the membrane are only accessible after a time delay, to permeating agents. Agents that permeate very rapidly will equilibrate with internal proteins (hemoglobin) producing small transient effects on the membrane, whereas agents that penetrate slowly will produce larger more prolonged effects. The mode of penetration is of importance. Sulfhydryl groups within an intrinsic protein channel will only be affected if the mercurial can penetrate into that channel. Although all mercurials can react with high specificity with sulfhydryl groups, structural factors relating to the membrane architecture and the capacity of different agents to penetrate into the membrane, lead to considerable diversity in their effectiveness against particular functions. Mercurials with different capacities to penetrate can be effective tools in determining the arrangement of functional proteins in the membrane and in determining how they work.

Cell Membrane Permeability↗
PubMed1981

The ego: an evolving construct.

This paper has attempted to enlarge and elaborate the concept of the representational world as a substructure of the ego. Toward that end a variety of Freud's definitions of ego are presented at various phases of their conceptual development. Because the functional definition of the ego is the one most stressed by Freud (1923) and by post-Freudian elaborators, the definitions of the latter group (A. Freud, 1936; Waelder, 1936; Hartmann, 1939, 1950; Jacobson, 1964) are also presented. Most contemporary critiques (G. Klein, 1976; Kohut, 1977; Schafer, 1976) of the structural hypothesis centre on its mechanistic jargon and the energetic point of view. Although aspects of these critiques have validity I believe the radical paradigmatic alternatives they propose to be excessive. It is a premise of this paper than the elaboration of the concept of the representation world facilitates the understanding of clinical data reflective of intrasystemic conflict of the ego.

Concept Formation↗
PubMed1980

Intrinsic segments of band 3 that are associated with anion transport across red blood cell membranes.

After treatment of red cell ghosts with chymotrypsin, the predominant intrinsic peptides remaining in the membrane fraction are 15,000 and 9,000 daltons mol wt. After partial extraction with Triton X-100, the residual membrane vesicles have almost no other stained peptides and such vesicles are reported to carry out anion transport activities sensitive to specific inhibitors. In vesicles derived from cells treated with DIDS(4,4'-diisothiocyano-2,2'-stilbene disulfonic acid), an irreversible inhibitor of anion transport that is highly localized in an abundant intrinsic protein known as band 3, the probe is largely recovered in the 15,000 dalton peptide. The part of band 3 from which it is derived is a previously reported 17,000 transmembrane segment (Steck, T.L., Ramos, R., Strapazon, E., 1976, Biochemistry 15:1154). The 9,000-dalton peptide is present in the vesicles in a one-to-one mole ratio with the 15,000-dalton peptide, suggesting that both are derived from the same protein. This conclusion is supported by the finding that the 35,000-dalton C-terminal end of band 3, derived by chymotrypsin treatment of cells, is further proteolysed if the cells are converted to ghosts and its disappearance coincides with the appearance of the 9,000-dalton fragment. Evidence is presented that the 9,000-dalton fragment crosses the bilayer and that it is closely associated with the 15,000-dalton peptide.

4,4'-Diisothiocyanostilbene-2,2'-Disulfonic Acid↗
PubMed1980

The location of a disulfonic stilbene binding site in band 3, the anion transport protein of the red blood cell membrane.

The binding site for 4,4'-diisothiocyano-2,2'-stilbenedi sulfonic acid, a specific, potent, irreversible inhibitor of anion transport in red blood cells is located in a 15 000 dalton transmembrane segment of band 3, produced by chymotrypsin treatment of ghosts stripped of extrinsic proteins. The segment was cleaved into three fragments of 7000 daltons by CNBr. The C-terminus of the segment is located in the 7000 daltons by the N-terminus in one of the 4000 dalton fragment; the N-terminus in one of the 4000 dalton fragments; and the binding site for 4,4'-diisothiocyano-2,2'-stilbenedisulfonic acid in the middle 4000 dalton fragment. The latter was cleaved by N-bromosuccinimide into two fragments of 2000 daltons. The binding site for 4,4'-diisothiocyano-2,2'-stilbenedisulfonic acid was located on the fragment containing the newly formed N-terminus. It is concluded that the binding site is located about 9000 daltons from the C-terminus (at the outside face of the membrane) and 6000 daltons from the N-terminus (at the cytoplasmic face). In view of the existing evidence that the binding site may be located near the outside face of the membrane, it is suggested that the 15 000 dalton segment is folded, so that it crosses the bilayer three times.

4-Acetamido-4'-isothiocyanatostilbene-2,2'-disulfo↗
PubMed1980

Inorganic anion transport in kidney and intestinal brush border and basolateral membranes.

The efflux of inorganic anions from purified brush border and basolateral membrane vesicles from dog kidney cortex was measured under equilibrium exchange conditions. Marked differences in temperature sensitivity and effects of inhibitors were found between the Cl and SO4 transport pathways and between the two types of membranes. SO4 transport in both brush border and basolateral membranes was markedly reduced by cooling, but significant inhibition by 4,4'-diisothiocyano-2,2'-disulfonic stilbene (DIDS) was only observed in basolateral vesicles. In contrast, Cl efflux from both types of vesicles was neither substantially inhibited by DIDS nor by lowering the temperature to 0 degrees C. Phosphate efflux from basolateral membrane vesicles was found to be only partially sensitive to DIDS. Attempts to label the stilbene-sensitive SO4 pathway in basolateral vesicles using [3H2]DIDS as a marker were unsuccessful due to the nonspecific labeling of many membrane components. The asymmetry in inorganic anion transport behavior exhibited by brush border and basolateral membrane vesicles from dog renal proximal tubule was also observed in equivalent vesicles prepared from rat small intestine.

Alkaline Phosphatase↗
PubMed1980

Psychoanalytic paradigms and their narcissistic investment.

The irrational elements in paradigm evolution, propagation, and competition have been explored. A central premise is that the narcissistic investment of a paradigm is an important contribution to the irrational process of paradigm evolution. Kuhn's (1962, 1970) ideas are summarized. An extrapolation and application of his ideas to the history of the evolution of psychoanalytic paradigms is attempted.

Humans↗
PubMed1980

Toward a critique of the psychology of the self.

A critique of Kohut's "psychology of the self" is presented. This critique derives from the author's view that paradigm competition often unnecessarily polarizes and accentuates differences while obfuscating rather than facilitating communication. An attempt is made to delineate Kohut's valuable contributions and to integrate them within the structural hypothesis . In addition, a critique of a number of issues that are incompletely or "inexactly" elaborated within Kohut's paradigm is presented.

Adolescent↗
PubMed1979

Transmembrane effects of irreversible inhibitors of anion transport in red blood cells. Evidence for mobile transport sites.

Experiments were designed to determine whether band 3, the anion transport protein of the red cell membrane, contains a mobile element that acts as a carrier to move the anions across a permeability barrier. The transport site-specific, nonpenetrating irreversible inhibitor 4,4'-diisothiocyano-2,2'-stilbene disulfonate (DIDS) was found to be effective only when applied extracellularly. It was used to sequester transport sites on the extracellular side of the membrane in intact cells. The membranes were then coverted into inside-out vesicles. The number of anion transport sites available on the cytoplasmic side of the vesicle membranes was then estimated by measuring the binding of N-(-4-azido-2-nitrophenyl)-2-aminoethyl-sulfonate (NAP-taurine), a photoreactive probe. Pretreatment with DIDS from the extracullular side substantially reduced the binding of NAP-taurine at the cytoplasmic side. Since NAP-taurine does not appear to penetrate into the intravesicular (normally extracellular) space, a transmembrane effect is apparently involved. About 70% of the DIDS-sensitive NAP-taurine binding sites are located in band 3, with the remainder largely in a lower molecular weight (band 4) region. A similar pattern of reduction in NAP-taurine binding is produced by high concentrations of Cl-, but this anion has little or no effect in vesicles from cells pretreated with DIDS. Thus the DIDS-modulated sites seem to be capable of binding either NAP-taurine or Cl. It is suggested that band 3 contains a mobile transport element that can be recruited to the extracellular surface by DIDS, thus becoming unavailable to NAP-taurine at the cytoplasmic face of the membrane. The results are consistent with a model of carrier-mediated transport in which the movement of the transport site is associated with a local conformational change in band 3 protein.

Binding Sites↗