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Biomedical subjects

M Morrison

Publications and source records attributed to M Morrison.

At least 109 records · Page 6Linked to original sources
PubMed1982

Interaction of a mouse macrophage cell line with homologous erythrocytes.

The interaction of the IC-21 murine macrophage cell line and homologous red blood cells (RBC) was assessed in the absence of exogenous opsonins. These results were used to evaluate this system as a potential model for macrophage-mediated clearance of old or damaged RBC. The binding and ingestion of density-separated and unseparated RBC by IC-21 cells were quantitated in assays that involved both 51Cr-labeled RBC and direct microscopy. The number of unseparated RBC that bound to IC-21 macrophages depended on the number of RBC added. Macrophages phagocytized an appreciable proportion of RBC within 3 hours with the ratio of RBC:macrophage of 10, a point at which the RBC-binding was not rate limiting. The mouse RBC were separated into dense- and less-dense fractions which are presumably enriched for old and young cells, respectively. When these RBC fractions were incubated with the IC-21 macrophage, significantly more of these dense cells were phagocytized. These results show that IC-21 macrophage cell line is a useful model for defining the processes whereby aged or damaged RBC are recognized and removed from circulation by macrophages.

Animals↗
PubMed1981

Naloxone suppresses food/water consumption in the deprived cat.

Intraperitoneal administration of the opiate antagonist, naloxone hydrochloride, resulted in decreased food and water consumption in drug-naive cats. In a cross-over Latin Square design, food consumed by six cats in a one hour period following 23 hours of deprivation, was decreased significantly below control (p less than 0.05) in linear relation to increasing dose (1 mg/kg and 10 mg/kg) of naloxone. Non-linear and time/order effects were not significant. Water consumption was decreased below control in a linear relation to increasing dose (1 and 10 mg/kg) for 5 of 6 cats at the 0.05 significance level. Non-linear and time/order effects on water consumption were not statistically significant for the same 5 cats. These results, and behavioral signs (i.e., vomiting, persistant vocalization, heavy salivation, mydriasis, moderate catatonia, and hissing) occasionally exhibited by four of the six cats in a 1-hr period following injection of the high dose, suggest a malaise-effect of naloxone.

Animals↗
PubMed1981

Protein architecture of the erythrocyte membrane.

The normal human erythrocyte is comprised of as many as 90 polypeptides. These membrane polypeptides are organized asymmetrically within the membrane. In a well-washed erythrocyte, all the polypeptides exposed on the outside surface are transmembrane proteins. Six such polypeptides have been identified. They are the anion transport component protein 3, the glucose transport protein 4.5 and the sialoglycoproteins PAS 1, 2', 2 and 3. The major membrane protein, protein 3, which comprises 25% of the total membrane peptide, interacts on the cytoplasmic surface with the cytoskeletal components. The sialoglycoprotein PAS 2 has also been shown to interact with cytoskeleton and has been named glycoconnectin. Employing a monolayer freeze-fracture technique, the transmembrane proteins have been shown to distribute asymmetrically. For example, the major sialoglycoproteins distribute with the outer half of the bilayer (E-face) while protein 3 is found exclusively on the inner half of the bilayer (P-face). The anchoring of the transmembrane proteins determines on which half of the bilayer the protein will be found. Well-defined fragments of the sialoglycoprotein are produced by the freeze-fracture procedure indicating that selected covalent bonds of these transmembrane proteins were broken. Correlation of these results with the appearance of intramembrane particles on the E- and P-faces indicate that protein 3 may account for most of the intramembrane particles found on the P-face, while the sialoglycoproteins probably account for little, if any, of the particles. Although the evidence is not conclusive, protein 4.5 may account for the particles on the E-face of the freeze-fractured human erythrocyte membrane.

Blood Proteins↗
PubMed1981

Glycoconnectin (PAS 2), a membrane attachment site for the human erythrocyte cytoskeleton.

The sialoglycoprotein PAS 2 is present in cytoskeletons generated by Triton X-100 extraction of isolated human erythrocyte stroma. However, removal of the peripheral cytoskeletal proteins by elution with 0.1N NaOH prior to Triton extraction renders PAS 2 Triton-soluble. This suggests association of PAS 2 with the cytoskeletal elements lining the inner surface of the erythrocyte membrane. For this reason, we are proposing the name glycoconnectin for PAS 2, since it is a glycoprotein which connects the core of the cytoskeleton to the membrane bilayer. The cytoskeletal proteins bands 4.1a,b also appear to interact directly with the membrane, since all of the other peripheral membrane proteins can be eluted with NaOH, pH 11.5, without releasing bands 4.1a,b from the membrane. Removal of spectrin and actin from the membrane results in the solubilization of both glycoconnectin and bands 4.1a,b by Triton X-100. Glycoconnectin is not present in the cytoskeletons derived from a donor whose membranes are devoid of bands 4.1a,b. These data suggest that glycoconnectin may interact directly with bands 4.1a,b.

Blood Proteins↗
PubMed1980

Effect of adenosine on concanavalin A agglutination of human erythrocytes.

We have attempted to correlate the functional activity of protein 3 with its activity as a receptor for concanavalin A. The concanavalin A agglutination of human erythrocytes is enhanced by adenosine. It varies with time of storage of the blood and is dependent on the concentration of adenosine in the medium. Adenine and/or inosine, which increase cellular ATP, do not substitute for adenosine in enhancing agglutination, and adenosine enhances agglutination of fresh erythrocytes with normal levels of ATP. Thus, it appears that cellular ATP levels are not directly involved in modulation of concanavalin A agglutination by adenosine. Trypsin, which hydrolyzes most of the exposed proteins of the cell surface but does not alter protein 3, enhances concanavalin A agglutination without altering the relative response to the cell to adenosine. Glucose, as well as the glucose transport inhibitors maltose and cellobiose, inhibits agglutination. High concentrations of adenosine reverse the inhibition by glucose and enhance agglutination in the presence of maltose and cellobiose. Treatment of erythrocytes with 4,4'-diisothiocyanostilbene-2,2-disulfonic acid disodium salt, which selectively inhibits the anion transport function of protein 3, substantially inhibits adenosine-supported concanavalin A agglutination. Treatment of erythrocytes with iodoacetate under conditions in which it selectively reacts with glyceraldehyde-3-phosphate dehydrogenase inhibits agglutination. Adenosine protects this dehydrogenase in erythrocytes from inactivation by iodoacetate, over the same concentration range in which it enhances agglutination.

Adenosine↗
PubMed1979

Effect of endo-beta-galactosidase on intact human erythrocytes.

Endo-beta-galactosidase, a glycosidase that hydrolyzes Gal beta 1-4 GlcNAc linkages in glycoconjugates, has been used to probe the plasma membrane of human erythrocytes. Coomassie blue staining of stroma components separated by sodium dodecyl sulfate-acrylamide gel electrophoresis indicates that treatment of red cells with endo-beta-galactosidase converts Protein 3, the anion transporter of the erythrocyte, to a more compact staining band. No other components detected by Coomassie staining are affected. Following labeling of red cells with galactose oxidase + NaB3H4, 45 to 50% of the [3H]galactose residues can be released by endo-beta-galactosidase. In contrast, only 5% of the label incorporated by treatment with periodate + NaB3H4, can be removed. [3H]Galactose residues are released from three components: Protein 3, Band 4.5, and the megaloglycolipids. The susceptibility of these components to endo-beta-galactosidase, together with the high content of Gal and GlcNAc present in Protein 3 and the megaloglycolipids, suggests that the erythrocyte membrane contains several components with N-acetyllactosamine repeating units, a structure commonly found in connective tissue glycoconjugates.

Erythrocyte Membrane↗
PubMed1979

Distribution of transmembrane polypeptides in freeze fracture.

Human erythrocytes have been freeze-fractured, and the polypeptides associated with the separate halves of the membrane bilayer have been analyzed by sodium dodecyl sulfate polyacrylamide gel electrophoresis. The transmembrane proteins were differentially separated by the fracture process. Although sialoglycoproteins associated with the outer half of the membrane, the anion transport protein (band 3) mainly remained with the inner half of the membrane. Well-defined fragments of the sialoglycoproteins were produced by the freeze-fracture procedure, indicating that selected covalent bonds of these transmembrane proteins were broken.

Erythrocyte Membrane↗
PubMed1977

Calcium effects on human erythrocyte membrane proteins.

The effects of Ca2+ on human erythrocyte membrane proteins were examined by sodium dodecyl sulfate (SDS) polyacrylamide gel electrophoresis. Ca2+ had several effects on normal human erythrocyte membrane proteins. It affected the binding of cytoplasmic proteins to the membrane, produced a non-reversible aggregation of several membrane proteins and activated apparent proteolysis of membrane proteins. The Ca2+ effect could be obtained with isolated, washed membranes when the erythrocyte cytoplasm was added. These studies indicate that the Ca2+-induced membrane proteolysis and aggregation effects are not due simply to its presence at the time of hemolysis as previously suggested (Carraway, K.L., Triplett, R.B. and Anderson, D.R. (1975) Biochim. Biophys. Acta 379, 571-581), but are the result of more complex interactions between the erythrocyte membrane and cytoplasmic factors.

Calcium↗
PubMed1977

Lactoperoxidase-catalyzed iodination of horse cytochrome c:monoiodotyrosyl 74 cytochrome c.

Iodination of horse cytochrome c with the lactoperoxidase-hydrogen peroxide-iodide system results initially in the formation of the monoiodotyrosyl 74 derivative. This singly modified protein was obtained in pure form by ion exchange chromatography and preparative column electrophoresis. It shows an intact 695 nm absorption band, the midpoint potential of the native protein, a nuclear magnetic resonance spectrum which indicates an undisturbed heme crevice structure, a normal reaction with antibodies directed against native horse cytochrome c, and circular dichroic spectra in which the only changes from those of the native protein can be ascribed to the spectral properties of iodotyrosine itself. This conformationally intact derivative reacts with the succinate-cytochrome c reductase and the cytochrome c oxidase systems of beef mitochondrial particle preparations indistinguishably from the unmodified protein, showing that the region including tyrosine 74 is not involved in these enzymic electron transfer functions of the protein. The circular dichroic spectra of this derivative indicate that the minima observed at 288 and 282 nm in the spectrum of native ferricytochrome c originate from tyrosyl residue 74.

Animals↗
PubMed1977

Detection of a variant of protein 3, the major transmembrane protein of the human erythrocyte.

A variant of the major transmembrane protein of the human erythrocyte has been detected following proteolytic digestion of intact erythrocytes. Pronase digestion of normal erythrocytes gives rise to a 60,000 molecular weight fragment of Protein 3, while digestion of erythrocytes with the variant protein produces two fragments of 60,000 and 63,000 molecular weight when peptides are separated by sodium dodecyl sulfate-acrylamide gel electrophoresis using the discontinuous buffer system of Laemmli (Laemmli, U. K. (1970) Nature 227, 680-685). The two fragments cannot be resolved if electrophoresis is conducted using the continuous phosphate or Tris/acetate buffer systems. This increased molecular weight of the variant fragment does not appear to be due to increased glycosylation, since neither sialic acid residues nor terminal galactose units can be detected. Furthermore, the transmembrane segment of Protein 3 can be detected after proteolytic digestion at both the external and cytoplasmic membrane surfaces. These transmembrane segments of both the normal and the variant peptide have identical molecular weights of 20,000 to 21,000. These results suggest that the increased molecular weight of the variant peptide is due to the incorporation of an additional segment into that region of the molecule which is exposed at the cytoplasmic side of the membrane.

Electrophoresis, Disc↗