Search PubMed⌕ Search

Biomedical subjects

J Glass

Publications and source records attributed to J Glass.

At least 127 records · Page 7Linked to original sources
PubMed1980

Transferrin-binding and iron-binding proteins of rabbit reticulocyte plasma membranes. Three distinct moieties.

1. Transferrin-membrane complexes and iron-binding membrane complexes were solubilized with sodium dodecyl sulfate from the plasma membranes of reticulocytes that had been incubated with (59Fe,125I)-labeled transferrin. Gel filtration of solubilized material demonstrated 125I-labeled transferrin complexed to two moieties, a minor component (Peak I) of apparent molecular weight 435,000 and a major component (Peak II) of apparent molecular weight 200,000. Most of the membrane 59Fe was located in Peak I. 2. Sepharose-bound anti-transferrin was used to purify the 125I-labeled transferrin-membrane complexes. The 59Fe/125I ratio in the transferrin complex purified from Peak I was the same as in the original transferrin and thus contained membrane-bound transferrin to which the 59Fe was still attached. The 59Fe/125I ratio in the purified Peak II transferrin complex was 0.33 times that of the original transferrin, indicating that more than 60% of its 59Fe had been delivered to the reticulocyte. 3. The purified transferrin complexes analyzed by SDS-polyacrylamide gel electrophoresis demonstrated a single band of apparent molecular weight 78,000 both by Coomassie blue stain for protein and by 125I radioactivity. The specific activity of this material was 0.27 and 0.56 times that of the original transferrin for Peak I and Peak II, respectively, indicating that transferrin in Peak I and II was bound to a membrane component with a molecular weight similar to that of transferrin. 4. The isoelectric focusing pattern of the Peak II transferrin complex showed isoelectric points of pH 6.7 and 6.2 compared to pH 5.4 for transferrin. 5. On the basis of these studies we propose that transferrin is first bound to a membrane protein and then delivers iron to a membrane component distinct and separate from the transferrin-binding moiety. Prior to its release, transferrin markedly depleted of iron is still bound to a component in the plasma membrane.

Animals↗
PubMed1980

Cytosol intermediates in the transport of iron.

Three 59Fe-labeled nonheme components of the cytosol were identified when rabbit reticuloyctes were incubated with 59Fe-labeled plasma under conditions in which the iron supply was not limiting. Two of these components were identified as ferritin and transferrin. The latter was characterized by gel filtration as having apparent molecular weight higher than transferrin, indicating that the transferrin may be complexed to another moiety. The third component, referred to as iron-binding protein-I (IBP-I), is as yet uncharacterized. When the reticulocytes were incubated with unlabeled plasma after pulse-labeling with 59Fe-labeled plasma, 59Fe radioactivity in these cytosol components decreased; after 15 min of chase, the 59Fe in ferritin, transferrin, and IBP-I fell to 64.6%, 26.5%, and 65.8% of the initial values, respectively. A good correlation existed between the decrease of 59Fe in these three nonheme compartments and the associated increase in 59Fe-heme. The data presented suggest that cytosol ferritin, transferrin, and IBP-I are intermediates in the transport of 59Fe from the plasma membrane to the mitochondria.

Animals↗
PubMed1979

Huntington's chorea in a black family: a report of 2 cases.

Two cases of Huntington's chorea occurring in a Black family are presented. One patient had, in addition, an arteriovenous anomaly of the cerebral circulation. The genealogy of the family is described and the probability of mixed descent is noted. The impression gained from the literature that Huntington's chorea rarely occurs in Blacks is strengthened.

Adult↗
PubMed1979

Transferrin binding and iron transport in iron-deficient and iron-replete rat reticulocytes.

Three aspects of iron metabolism were studies in reticulocytes from iron-deficient, phlebotomized, and phenylhydrazine-treated rats: (1) the number of transferrin binding sites; (2) the uptake of 59Fe-transferrin; and (3) the ability of cytosol to mobilize 59Fe from 59Fe-labeled reticulocyte plasma membrane. The number of transferrin binding sites, assayed by measuring the binding of 125I-labeled transferrin to reticulocytes, were similar in iron-deficient and phlebotomy-induced reticulocytes, 66,000 and 75,000 binding sites/cell, respectively, but were about doubled, 120,000 binding sites/cell, in phenylhydrazine-induced reticulocytes. Uptake of 59Fe into iron-deficient reticulocytes was about one-half that for phlebotomy-induced reticulocytes and one-quarter that for phenylhydrazine-induced reticulocytes, the rates of uptake being measured as 21,540, 41,233, and 79,600 molecules of 59Fe per minute per cell, respectively. The mobilizing activity of cytosol free iron-deficient reticulocytes was also about one-half that of cytosol from phlebotomy-induced reticulocytes and about one-quarter that of cytosol from phenylhydrazine-induced reticulocytes. These results indicate that instead of a compensatory increase in these aspects of iron metabolism, the iron-deficient reticulocyte had a decreased ability to transport iron.

Anemia, Hypochromic↗
PubMed1978

Mobilization of iron from the plasma membrane of the murine reticulocyte. The role of ferritin.

1. Plasma membranes prepared by pre-incumbation of mouse reticulocytes with 125I, 59Fe-labeled murine transferrin were able to release 59Fe in preference to 125I when incubated in the presence of murine reticulocyte cytosol, demonstrating that the latter mobilized iron which had been dissociated from transferrin. 2. 59Fe in cytosol was associated with at least two components in addition to hemoglobin, a high molecular weight component, identified as ferritin by specific immunoprecipitation, and an as yet unidentified, low molecular weight component of approx 17 00. 3. Ferritin itself, in the absence of added cytosol, was abloe to mobilize 59Fe from s9Fe-labeled reticulocyte plasma membranes. 4. Lysates of reticulocytes synthesized 59Fe-labeled heme when incubated with 59Fe-labeled ferritin. 5. These findings reflect a pathway of iron uptake and incorporation into heme in which ferritin plays an active role.

Animals↗
PubMed1978

[Involvement of thalamic nuclei in the formation of conditioned avoidance responses in rats. III. Lesions of the nucleus ventralis medialis].

Bilateral lesions of the nucleus ventralis medialis thalami (VM) did not change the reactivity to sensory and painful stimuli, the preoperatively fixed motor patterns and the preoperatively elaborated conditioned avoidance response (CAR, jumping test) in hooded rats (Long-Evans-strain). The postoperative acquisition of a CAR in a runway was attained as in controls, but with significantly higher running speed. During continuation of the training in a Y-maze using a 2:2-alternation schedule the CAR decreased gradually to zero as a consequences of increasing reaction times (time from onset of the acoustic conditioned signal to the onset of running). At least the lesioned animals only started with the onset of the painful reinforcement. In spite of the non-avoidance these animals learned to escape correctly through the illuminated floor (dark-light-discrimination). The results are discussed as a consequence of a deficit in conditioning of locomotor programs.

Animals↗
PubMed1977

The cross-linking of 125I-labelled transferrin to rabbit reticulocytes.

125I-labelled transferrin has been covalently linked to proteins of rabbit reticulocyte membranes using three different cross-linking reagents: (a) bis(methyl) suberimidate (b) 4-methyl mercaptobutirimidate and (c) Cu-o-phenanthroline. Analysis of the products of the cross-linking reactions by SDS polyacrylamide gel electrophoresis revealed three radioactively labelled components. The major component corresponds to non-cross-linked transferrin while a second smaller component represents a complex (125 000 daltons) of membrane protein and transferrin. A third component (210 000 daltons) was observed when 4-methyl mercaptobutirimidate was used as a cross-linking reagent. The possibility that the two higher molecular weight complexes contain the receptor protein for transferrin is discussed.

Animals↗
PubMed1977

Enzymes as reagents in peptide synthesis: enzyme-labile protection for carboxyl groups.

N-Benzyloxycarbonyl derivatives of isoglutamine and isoasparagine were coupled with arginine methyl ester through the action of dicyclohexylcarbodiimide. The resulting benzyloxycarbonyl derivatives of isoglutaminylarginine methyl ester and isoasparaginylarginine methyl ester were treated with trypsin for removal of the ester groups and then with porcine pancreatic carboxypeptidase B for liberation of arginine and the original benzyloxycarbonyl derivatives of isoglutamine and isoasparagine. This scheme represents a reversible masking of the side-chain carboxyl functions of aspartic and glutamic acid residues. Possible applications of esters and amides of arginine as reversible blocking groups in protein semi-synthesis are discussed along with prospects and strategies for developing related techniques of higher efficiency.

Asparagine↗
PubMed1977

Transferrin receptors in developing murine erythroid cells.

Techniques of cell separation were used to isolate murine erythroid cells at different stages of maturation. The number of transferrin receptors in these cell populations was assayed by measuring binding of 125I-labelled transferrin. Nearly 23 times as many receptors were found in the least mature cells, chiefly pronormoblasts, as in reticulocytes. Iron transport, determined by measurement of the rate of 59Fe uptake from 59Fe-labelled transferrin, was proportional to the number of receptors at all stages of differentiation. Electron microscope radioautographic studies of the interaction of 125I-labelled transferrin with erythroid precursor cells demonstrated that 15-33% of cell associated transferrin was intracellular in erythroid precursors.

Animals↗
PubMed1977

Effect of intra-articular corticosteroid injections on primate cartilage.

An attempt was made to ascertain whether intra-articular corticosteroids exert a harmful effect on primate cartilage. The knee joints of 10 Macaca irus monkeys were subjected to either one, two, or six injections of 20 mg methyl prednisolone or an equal number of control injections over a 12-week period. Minor degenerative changes of many femoral condyles were shown by India ink staining and by a system of histochemical grading. Changes in the joints injected with corticosteroid were not significantly different from those seen in control joints. The findings were in striking contrast to the severe degeneration reported by others in rabbit joints injected with corticosteroid. The experiment did not support the contention that intra-articular corticosteroids invariably have a deleterious effect on primate cartilage.

Animals↗
PubMed1977

Increased incidence of malignancy in chronic renal failure.

We have analysed the causes of death in a group of patients with chronic renal failure--serum creatinine more that 225 mumol/l (2.5 mg/100 ml)--and find that there is an increased incidence of malignancy when compared with the fatality rates for cancers in England and Wales (p less than 0.0005). No patient in the series had received a transplant kidney or was therapeutically immunosuppressed for other reasons.

Adult↗
PubMed1977

External surface membrane proteins in normal and neoplastic murine erythroid cells.

The development pattern of one class of plasma membrane proteins, the external surface proteins, was examined in neoplastic and nonneoplastic differentiating murine erythroid cells. Neoplastic erythroid precusor cells were obtained from spleens of CD-1 mice after infection with Friend erythroleukemia virus while the nonneoplastic ellls were obtained from spleens of mice with phenylhydrazine-stimulated erythroid hyperplasia. Erythroid precursors at different stages of development were isolated from these erythroid cell populations by sedimentation at unit gravity. The surface proteins were labeled by lactoperoxidase-catalyzed iodination, solubilized in sodium dodecyl sulfate, and separated by sodium dodecyl sulfate gradient gel electrophoresis. Multiple labeled bands were found at all stages of neoplastic and nonneoplastic erythroid differentiation examined. The pattern of external membrane proteins labeled in nonneoplastic erythrocytes and in reticulocytes from peripheral blood were qualitatively similar and not altered by infection with Friend virus. The nucleated precursor cells from noninfected mice exhibited distinct differences from erythrocytes, and with increaseing differentiation an evolutionary pattern of several minor proteins was seen. Clear-cut differences in lactoperoxidast-reactive proteins were also observed between neoplastic and nonneoplastic precursors. The most marked differences were observed between the most immature cells. The youngest neoplastic cells from CD-1 mice possessed a protein with a molecular weight of 8000 not seen in normal erythroid cells. Additionally, there was an absence of a normally occurring protein with a molecular weight of 13,000 and increased amounts of a protein with a molecular weight of 140,000. With increasing maturation of the neoplastic cells, labeling of the protein with a molecular weight of 8,000 decreased while the protein with a molecular weight of 13,000 became apparent, so that a labeling pattern similar to that of nonneoplastic cells was obtained. These studies deomnstrate both distinct alterations of lactoperoxidase-reactive surface membrane proteins in nonneoplastic erythroid cells druring cell maturation in neoplastic erythroid cells as compared with nonneoplastic erythroid cells at similar stages of development.

Animals↗