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Biomedical subjects

M Morrison

Publications and source records attributed to M Morrison.

At least 73 records · Page 4Linked to original sources
PubMed1990

Frequencies of Band 3 variants of human red cell membranes in some different populations.

A variant of Band 3, the major protein of the erythrocyte membrane, was observed by Mueller and Morrison in 1977 in 6-7% of healthy blood donors on sodium dodecyl sulphate-polyacrylamide gel electrophoresis (SDS-PAGE) of erythrocyte membranes treated with pronase. Pronase treated red cells containing this first recognized variant [here designated 'Band 3-Memphis (m)'] section had two bands of about 63,000 and 60,000 Mr while pronase treated normal cells had only the lighter Mr band. The present study includes data on the frequency of variants resembling Band 3-Memphis in patients of different ethnic groups and on random donors obtained earlier in Memphis. These variants were detected by the original method of Mueller and Morrison and were not associated with recognized clinical or haematological abnormalities. Significantly higher gene frequencies for the variants of the (m) type were observed in American Indians, African Americans and Filipinos than in Caucasians; putative heterozygotes and homozygotes were identified among each of these groups. The frequency of silent Band 3 polymorphisms in different populations should be considered in the interpretation of clinical findings associated with the presence of Band 3 variants.

Anion Exchange Protein 1, Erythrocyte↗
PubMed1990

The INR--a help or a hindrance to warfarin dosage?

We have examined the INR values of 128 warfarin patients obtained by four different techniques in common use in Scotland namely venous and capillary. Thrombotest and venous and capillary Prothrombin Time (PT). The PT INRs were carried out using Manchester Reagent thromboplastin. Discrepant INR values were obtained. The mean Manchester venous INR values were lower than those obtained by the other three methods (p less than 0.0001). This suggests that patient's dosed by reference to Manchester venous INR are liable to receive more warfarin than those dosed by the other methods.

Blood Coagulation Tests↗
PubMed1989

Cognitive-behavioral treatment of recurrent nonspecific abdominal pain in children: an analysis of generalization, maintenance, and side effects.

From 10% to 15% of school-aged children experience recurring abdominal pain. This study evaluated the efficacy of a cognitive-behavioral program for the treatment of nonspecific recurrent abdominal pain (RAP) using a controlled group design. The multicomponent treatment program consisted of differential reinforcement of well behavior, cognitive coping skills training, and various generalization enhancement procedures. Multiple measures of pain intensity and pain behavior were conducted, including children's self-monitoring, parent observation, teacher observation, and observation by independent observers. Results showed that both the experimental and the control groups reduced their levels of pain. However, the treated group improved more quickly, the effects generalized to the school setting, and a larger proportion of subjects were completely pain-free by 3-months follow-up (87.5% vs. 37.5%). There was no evidence for any negative side effects of treatment.

Abdomen↗
PubMed1989

New etiology for intestinal uptake of thallium-201.

A patient with both rest and exercise thallium images for unstable angina demonstrated marked large intestinal uptake of thallium. However, the thallium uptake in the large intestine was noted only after exercise. The only change in the patient status between the two studies was the administration of verapamil. Thus, verapamil administration has been demonstrated to be a new cause for gut uptake of thallium.

Angina, Unstable↗
PubMed1989

Discrepant INR values: a comparison between Manchester and Thrombotest reagents using capillary and venous samples.

The International Sensitivity Index (ISI) for different thromboplastin reagents is obtained by calibration against WHO reference preparations. It is hoped that calculation of the International Normalized Ratio (INR) from the ISI will permit accuracy and conformity in reporting laboratory assays of warfarin effect even across a range of different techniques. We have examined the INR values of 128 warfarin patients obtained by four different techniques in common use, namely venous and capillary Thrombotest and venous and capillary Manchester reagent. Discrepant INR values were obtained. The mean Manchester venous INR values were lower than those obtained by the other three methods (P less than 0.0001). This suggests that patients dosed by reference to Manchester venous INR are liable to receive more warfarin than those dosed by the other methods.

Animals↗
PubMed1988

Ca2+-mediated catabolism of human erythrocyte band 3 protein.

Catabolism of human erythrocyte membrane band 3 protein in the presence of Ca2+ was studied. An increase in the amount of a 30 kDa amino terminal fragment of band 3 was observed when erythrocyte membranes were incubated for 30 min with 1 mM Ca2+ in the presence of whole erythrosol. Incubation of the membranes with Ca2+ alone did not result in band 3 breakdown. Generation of the 30 kDa fragment from band 3 was related to the action of a leupeptin-sensitive Ca2+-dependent proteinase in the cytosol. This proteinase was also responsible for the increased production of a 52 kDa and a 70 kDa transmembrane carboxyl terminal fragment of band 3. From the size of the generated fragments, it is deduced that in the presence of Ca2+ and Ca2+-dependent proteinase, band 3 protein is cleaved at the cytoplasm/membrane interface and along its cytoplasmic domain.

Anion Exchange Protein 1, Erythrocyte↗
PubMed1988

A statistical model of the timing mechanism of the erythrocyte life-span.

Three statistical models are introduced as explanations of erythrocyte senescence. For the sake of simplicity, we prefer the multievent model, in which one of the parameters represents the number of events (between 7 and 12) needed to signal likely senescence. Proteolysis of a dimeric protein, such as protein 3, accounts for four events in the model, if little of the protein is degraded by senescence. Although each model we propose accommodates the possibility of random destruction, this alternative does not fit well with available experimental data.

Blood Proteins↗
PubMed1987

Red blood cell homeostasis: recognition of distinct types of damaged homologous red blood cells by a mouse macrophage cell line.

The mouse macrophage (M phi) cell line IC-21 preferentially ingests a subpopulation of homologous red blood cells (MRBC) from normal mice. This subpopulation presumably bears the so-called transfusion lesion, a consequence of damage acquired during the drawing and processing of blood. To determine if all damaged MRBC were recognized by a common receptor site on IC-21 M phi, we prepared suspensions of MRBC damaged in vitro by treatment with tannic acid and compared the phagocytic uptake of these cells with those bearing the transfusion lesion. Trypsin treatment of IC-21 M phi rendered them unable to recognize MRBC bearing the transfusion lesion; but it had no effect on the uptake of tannic acid-damaged MRBC, showing that IC-21 M phi have separate recognition sites for these two populations of damaged MRBC.

Animals↗
PubMed1987

Membrane skeletal alterations during in vivo mouse red cell aging. Increase in the band 4.1a:4.1b ratio.

We have examined membrane protein profiles for alterations during red blood cell aging. To obtain populations of in vivo-aged red cells, we maintained mice in a state of continuous erythropoietic suppression for up to 8 wk using serial hypertransfusion. The circulating t1/2 of red cells from mice which had been erythropoietically suppressed for 8 wk was less than 1 d compared with a t1/2 of 15 d for red cells from normal animals. The most obvious alteration in membrane proteins was an increase in the ratio of the membrane skeletal components 4.1a:4.1b from 0.3 for the normal red cell population to greater than 1 for these old cells. The 4.1a:4.1b ratio thus appears to be a useful index of red cell age. Analyses of the density profile of cells aged in the hypertransfused mice disclosed that these old cells had a density range similar to that of controls, suggesting that cell density does not increase significantly with red cell age in the mouse.

Animals↗
PubMed1987

Are the red cell proteases a clock mechanism which turns on a signal of senescence?

The mammalian erythrocyte has a finite life span. In order to study the mechanism involved, a well-defined age group of erythrocytes must be obtained. Such cells are produced by a hypertransfusion system in mice. With this system, it was possible to show that the very oldest population of erythrocytes bind autoantibodies. This binding of the autoantibodies is not a gradual accumulation, but occurs primarily in the oldest red cells. The immunoglobulins bound are not isotype specific but reflect the isotype in the serum. The red cells with the oldest mean age are recognized and phagocytized most readily by peritoneal exudate macrophage in vitro. Earlier studies suggest that protein 3 may be involved in autoantibody binding. An investigation of protein 3 indicates that the human red cells contain well-defined catabolic products of this protein and there is little variation of these catabolic products among individuals both quantitatively and qualitatively. This suggests that there is a well-regulated catabolic system in the red cell. A study of the calcium-activated proteases, the only neutral proteases in the red cell, show that they do not directly generate the amino terminal catabolic fragments of protein 3 found in the erythrocyte.

Animals↗
PubMed1986

Phase II evaluation of megestrol acetate in previously treated patients with advanced breast cancer: relationship of response to previous treatment.

Thirty-seven patients with advanced breast cancer were treated with megestrol acetate 160 mg daily. All patients except two had been heavily pre-treated with hormonal therapy; eight patients also received chemotherapy. Complete and partial responses occurred in 25% with a mean duration of 5 months (range 2-24 months). A further 38% of patients had static disease for 2 months or greater. Seven patients had previously received medroxyprogesterone acetate, and responses were seen even in patients who had failed to respond to this therapy. This was thought to be due to the higher levels of progestogenic activity which can be routinely achieved with megestrol acetate. Toxicity was minimal, and we would therefore consider that megestrol acetate should be the progestogen of choice in advanced breast cancer.

Adult↗
PubMed1986

Erythrocyte homeostasis: antibody-mediated recognition of the senescent state by macrophages.

We tested the hypothesis that the accumulation of bound autologous antibody on a "senescent epitope" identifies aged erythrocytes for phagocytic removal by macrophages. Erythrocytes were collected from mice maintained on a hypertransfusion protocol designed to yield cells of defined age. The mouse erythrocytes were assayed for the presence of bound antibody by measuring their susceptibility to ingestion by macrophages from mouse peritoneal exudates and by flow cytofluorometry. Both assays disclosed that only the oldest mouse erythrocytes bore detectable levels of antibody. Flow cytofluorometric analysis revealed that the frequency distribution of IgG isotypes bound to the cells reflected their levels in normal serum. Finally, treatment with trypsin abolished the ability of the macrophages to ingest erythrocytes aged in vivo. These findings support the hypothesis that antibody mediates the clearance of senescent mouse erythrocytes from the circulation and demonstrate that the presence of a trypsin-sensitive recognition structure on macrophages is an essential requirement in this homeostatic process.

Animals↗
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↗