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Biomedical subjects

M Morrison

Publications and source records attributed to M Morrison.

At least 91 records · Page 5Linked to original sources
PubMed1986

Paroxysmal nocturnal hemoglobinuria erythrocytes are of two distinct types: positive or negative for acetylcholinesterase.

Paroxysmal nocturnal hemoglobinuria (PNH) is an acquired disorder. Erythrocytes isolated from PNH patients show increased sensitivity to complement and decreased acetylcholinesterase (AChE) activity. In this study, indirect immunofluorescence analysis of a monoclonal antibody specific for a surface epitope of human erythrocyte AChE is used to quantitate the content of this enzyme at the single-cell level. Flow-cytofluorimetric analysis of erythrocytes from normal donors indicates that all erythrocytes contain detectable levels of the surface epitope with a strong correlation between cell size and enzyme content. In contrast, erythrocytes from PNH patients show two distinct populations of erythrocytes; namely, those containing a normal content of AChE and a second population containing no detectable AChE. The AChE-negative population of cells is quantitatively complement-sensitive. These data support suggestions that PNH is a clonal disorder resulting in two distinct types of circulating erythrocytes. The abnormal clone produces cells that are both surface-AChE-negative and complement-sensitive. In addition, the method described provides an attractive alternative for the diagnosis and quantitative evaluation of abnormal erythrocytes in PNH patients.

Acetylcholinesterase↗
PubMed1985

Catabolism of the anion transport protein in human erythrocytes.

We identified the catabolic products of protein 3 in human erythrocytes. Protein 3, the major protein of the erythrocyte membrane, functions in anion transport and reacts covalently with tritiated 4,4'-diisothiocyano-1,2-diphenylethane-2,2'-disulfonic acid ([3H]DIDS), a very selective inhibitor of anion transport. In this study, [3H]DIDS was used to label protein 3 in the membranes of normal cells and those from a donor heterozygous for a variant of protein 3, defined by its elongated amino-terminal end. Both types of cells contained [3H]DIDS-labeled peptides other than protein 3. A protein fragment of 60K molecular weight was found in normal cells, whereas both 60K and 63K fragments were identified in cells from the heterozygote. These peptides are identical with those generated by treatment of intact erythrocytes with Pronase or chymotrypsin. A polyclonal rabbit antibody specific for the purified 60K fragment of protein 3 was used to detect this protein and its products in the erythrocyte membrane. Autoradiographs of membrane peptides that were separated by sodium dodecyl sulfate-polyacrylamide gel electrophoresis, transferred to nitrocellulose, and allowed to react with the monospecific antibody showed, in addition to protein 3, a 60K fragment and fragments in the 40K region and in the 20-30K region. Cells containing the protein 3 variant yielded two fragments showing a 3K difference in molecular weight in all three regions, demonstrating that degradation of protein 3 is identical in normal erythrocytes and those heterozygous for the variant. This observation also confirms the common derivation of the fragments from protein 3.(ABSTRACT TRUNCATED AT 250 WORDS)

4,4'-Diisothiocyanostilbene-2,2'-Disulfonic Acid↗
PubMed1985

A new variant of the anion transport protein in human erythrocytes.

The major plasma membrane protein of human erythrocytes is the anion transport protein, termed protein 3. We previously reported a variant form of protein 3 that is elongated on the amino-terminal end of the molecule, which is exposed on the cytoplasmic side of the membrane, but otherwise its features are identical with those of the normal molecule. We have termed this molecule protein 3 variant 1. We now report a new variant form, protein 3 variant 2. The erythrocyte donor was a double heterozygote whose red cells possess a normal protein 3 and a protein 3 variant which is elongated and possesses a second variation at the 4,4'-diisothiocyano-2,2'-stilbenedisulfonic acid (DIDS) reactive site. Variant 2 reacts with 4,4'-diisothiocyano-1,2-diphenylethane-2,2'-disulfonic acid (H2DIDS) more readily than does the normal molecule. At high pH values, H2DIDS acts as a bifunctional cross-linking agent; it cross-links the proteolytic products generated by Pronase (or chymotrypsin) treatment of variant 2 less efficiently than noted for normal protein 3 or the first variant. Thus, the newly identified molecule has an alteration at the DIDS reactive site, which is near the outer surface of the membrane. The results can be interpreted as indicating that the DIDS binding site of variant 2 is more exposed than the normal molecule, but further removed from the site on the carboxyl-terminal fragment involved in cross-linking. Although there is a difference in the reactivity of the two protein 3 chains in variant 2, the reaction of variants 1 and 2 and normal cells with varying concentrations of [3H]H2DIDS results in the same amount of incorporation in all cells. Since protein 3 exists as a dimer or higher aggregate in the membrane, these results may indicate an interaction between monomers.(ABSTRACT TRUNCATED AT 250 WORDS)

4,4'-Diisothiocyanostilbene-2,2'-Disulfonic Acid↗
PubMed1985

Phase II study of vincristine, mitomycin-C and mitoxantrone in advanced breast cancer: a preliminary report of response and toxicity.

Nineteen patients with advanced, previously treated breast cancer received treatment with vincristine 2 mg i.v., mitomycin-C 6 mg/m2 and mitoxantrone (Novantrone; dihydroxyanthracenedione) 12 mg/m2 i.v. every three weeks. Thirteen patients are evaluable for response and toxicity. Partial remission was seen in six patients, with soft tissue, bone and visceral metastases and static disease in a further four patients. Median duration of response has not yet been reached (8+ months). Toxicity was mild and predictable, with no patient experiencing severe nausea and vomiting, and only four of the patients requiring a wig for alopecia. Malaise and lethargy were common in those patients receiving more than three courses, and an increase in the mean corpuscular volume (MCV) together with a fall in haemoglobin were seen in patients receiving multiple courses of treatment. The study suggests that this combination is active, and may prove useful with other agents in the treatment of breast cancer.

Adolescent↗
PubMed1985

Penicillamine in ankylosing spondylitis: a double blind placebo controlled trial.

A double blind placebo controlled trial was carried out over a 6-month period on 17 patients with ankylosing spondylitis (AS) to assess the effect of the second line antirheumatic drug, D-penicillamine. The patients included 13 with peripheral joint involvement. No significant improvement over placebo was detected in a variety of clinical and laboratory indices in the patients receiving active treatment. This controlled trial would not support a use for penicillamine in AS.

Adult↗
PubMed1984

Reactions of ferryl lactoperoxidase (compound II) with sulfide and sulfhydryl compounds.

Lactoperoxidase in the ferryl state (compound II) reacts with sulfide to form a typical sulfheme -containing hemoprotein as do hemoglobin, myoglobin, and catalase. Ferrous sulflactoperoxidase is primarily formed and then oxidized to its ferric form under aerobic conditions. Similar reactions of lactoperoxidase occurs when methylmercaptoimidazole (MMI) is substituted for sulfide. The yield of the adducts from one-turnover reactions of ferryl lactoperoxidase is 100% with sulfide and about 20% with MMI. Sulfur and MMI of the adducts appear to be removed from the enzyme upon reduction by dithionite. Upon the reactions with cysteine and dithiothreitol, the enzyme is converted to spectral species, which are less characteristic but are similar to ferrous and ferric sulflactoperoxidases , respectively. We conclude that there is no essential difference in the mechanism of reactions of lactoperoxidase with sulfide, MMI, cysteine, and dithiothreitol.

Animals↗
PubMed1984

Diagnosis and management of hypertension: the stated practices of family physicians.

Hypertension is an important and common problem in family practice, but there is no general agreement on the systolic and diastolic pressures at which it should be diagnosed and treated. Responses from 273 family physicians surveyed by mail in Metropolitan Toronto showed a wide variation in the pressures used as cut-off points. The probability that in a given patient hypertension would be diagnosed or treated at different systolic and diastolic pressures varied considerably among the physicians, the variation increasing with the age of the patient. There was also wide variation in opinion among the surveyed physicians about how often patients should be screened for hypertension; depending on the patient's age, up to 35% of the physicians stated that the blood pressure should be measured at every visit. Only one third reported using any one or more methods to ensure that patients with hypertension were not lost to follow-up. The family physicians with an academic appointment used higher cut-off points for diagnosis and treatment, and they screened and scheduled follow-up visits less frequently than those without an academic appointment.

Adult↗
PubMed1984

Preferential phagocytosis of in vivo aged murine red blood cells by a macrophage-like cell line.

The ability of an established line of mouse macrophages (IC-21) to ingest red blood cells (RBC) aged in vivo was assessed. RBC populations of increasing age were prepared in mice by serial hypertransfusion, a procedure that inhibits erythropoiesis. Mouse RBC with a mean age of about 58 d (normal RBC life span, 60 d) had a circulating half-life of less than 1 d when transfused into normal mice. IC-21 macrophages ingested the in vivo aged RBC in preference to RBC from normal mice (mean RBC age, 30 d). RBC isolated from mice 10 d after being released from one red blood cell lifespan (60 d) of inhibited erythropoiesis (mean RBC age 5 d) were ingested significantly less than RBC from normal mice. The IC-21 macrophage line used with in vivo aged RBC affords a highly defined model system for identifying the mechanism(s) of macrophage-mediated homeostasis.

Animals↗
PubMed1983

The interaction of human erythrocyte Band 3 with cytoskeletal components.

Band 3 of the human erythrocyte is involved in anion transport and binding of the cytoskeleton to the membrane bilayer. Human erythrocytes were treated to incorporate varying concentrations of DIDS (4,4'-diisothiocyanostilbene-2,2'-disulfonic acid) a non-penetrating, irreversible inhibitor of anion transport, and both functions of Band 3 were analyzed. The rate of efflux of 35SO2-4 was measured and the binding of cytoskeletal components to the membrane was evaluated by extracting the membranes with 0.1 N NaOH and analyzing for the peptides remaining with the membrane. It was found that 0.1 N NaOH extracts all the extrinsic proteins from membranes of untreated cells, while, in the case of the membranes from cells treated with DIDS, a portion of the cytoskeletal components, spectrin (Bands 1 and 2) and Band 2.1 (ankyrin, syndein) remain with the membrane. The amount of these cytoskeletal components remaining with the membrane depends on the concentrations of DIDS incorporated. The effect of DIDS on the extractability of the spectrin-Band 2.1 complex correlates well with DIDS inhibition of anion transport (r = 0.91). At DIDS concentrations which completely inhibit anion transport, about 10% of total spectrin-Band 2.1 complex remains unextracted. Another anion-transport inhibitor, pyridoxal phosphate, has no effect on binding of the cytoskeleton to the membrane. On the other hand, digestion of DIDS-pretreated intact erythrocytes with Pronase, chymotrypsin, or trypsin releases the tight binding of Band 3 to cytoskeleton on the inside of the membrane. Since trypsin does not hydrolyze Band 3 the data suggest that a second membrane protein which is trypsin sensitive may be involved with Band 3 in cytoskeletal binding.

4,4'-Diisothiocyanostilbene-2,2'-Disulfonic Acid↗
PubMed1983

Does cell density correlate with red cell age?

We have examined age-related changes in red cells by employing a serial hypertransfusion protocol to generate populations of in vivo-aged mouse red cells. Studies of these old cells have revealed alterations in membrane components; namely, a conversion of band 4.1b to 4.1a and an increase in the amount of membrane-associated, Triton-insoluble globin. Furthermore, we have found that the erythrocyte does change in density, but only during the earliest stages of its life-span. As the cell continues to age, there is no longer a correlation between age and density.

Animals↗
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↗