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Biomedical subjects

C A Bell

Publications and source records attributed to C A Bell.

At least 37 records · Page 2Linked to original sources
PubMed1976

Anti-Wrb, and other autoantibodies responsible for positive direct antiglobulin tests in 150 individuals.

Eluates from the red blood cells (and sera whenever free autoantibody was present) of 150 individuals with positive direct antiglobulin tests, have been studied for antibody specificity. Of 87 patients with AIHA, 64 had autoantibodies reacting with all red cell samples including Rhnu11. Of these 64 anti-d1 autoantibodies, two were, and 32 contained, auto-anti-Wrb. Of 33 patients being treated with alphamethyldopa, who had developed positive direct antiglobulin tests, 23 had anti-d1 autoantibodies four of which contained auto-anti-Wrb. Of 30 haematologically normal donors with positive direct antiglobulin tests, 23 had anti-d1 autoantibodies, two of which were, and six of which contained, auto-anti-Wrb. The full specificities of autoantibodies, other than anti-Wrb and anti-d1, in the 150 patients are described, as are the natures of the protein red cell coatings that caused the positive direct antiglobulin tests. The presence of free serum autoantibody as a correlate of the three clinical conditions is reported. Several observations on auto-anti-Wrb are documented. The antibody can cause gross red cell destruction in vivo, but can be benign on other occasions; it occurs with approximately the same frequency in AIHA patients and "normal" donors with positive direct antiglobulin tests, but in fewer patients with alphamethydopa induced positive direct antiglobulin tests; it does not activate complement in vivo; and finally it may eventually provide a clue to the aetiology of AIHA.

Anemia, Hemolytic, Autoimmune↗
PubMed1975

Effects of external osmolality on polyamine metabolism in HeLa cells.

The polyamine content of Escherichia coli is inversely related to the osmolality of the growth medium. The experiments described here demonstrate that a similar phenomenon occurs in mammalian cells. When grown in media of low NaCl concentration, HeLa cells and human fibroblasts were found to contain high levels of putrescine, spermidine, and spermine. The putrescine content of HeLa cells was a function of the osmolality of the medium, as shown by growing cells in media containing mannitol or additional glucose. External osmolality per se had no effect on the contents of spermidine and spermine. For all media, the total cellular polyamine content could be correlated with the activity of ornithine decarboxylase, the first enzyme in polyamine biosynthesis. Different levels of enzyme activity appear to result solely from variations in the rate of enzyme degradation. A sudden increase in a NaCl concentration produced rapid loss of ornithine decarboxylase activity and a gradual loss of putrescine and spermidine. A sudden decrease in NaCl concentration led to rapid and substantial increases in ornithine decarboxylase activity and putrescine.

Culture Media↗
PubMed1974

Multiple transport components for putrescine in Escherichia coli.

Putrescine uptake was studied in cultures of Escherichia coli K-12 grown in media of high or low osmolarity. When grown in high osmolarity medium, a transport system of low K(m) and low V(max) was found. For cultures grown in a medium of low osmolarity, the kinetics of putrescine uptake was more complex and consistent with the existence of an additional transport system of higher K(m) and V(max). This conclusion is supported by the isolation of mutants in which one or the other system appears to be defective and by the ability of chloramphenicol to block the expression of the second transport system. Both systems appear to prefer putrescine over other compounds, since several basic amino acids and other polyamines competed only weakly for transport. The action of both uptake systems was shown to cause significant displacement of intracellular putrescine. Both systems also are at least partially energy dependent.

Amino Acids↗
PubMed1973

Polyamine requirements of a conditional polyamine auxotroph of Escherichia coli.

Escherichia coli MA-159 is deficient in agmatine ureohydrolase. After addition of exogenous arginine, the cellular putrescine content declines immediately and exponentially; however, the spermidine content remains normal for 3 h. The growth rate of such cultures, measured turbidometrically, slows gradually over many hours. Putrescine-depleted cultures grow especially slowly in media of low osmolarity, whereas nondepleted cultures grow at similar and rapid rates in media of either normal or low osmolarity. External osmolarity also affects the ability of various exogenous polyamines to stimulate growth of putrescine-depleted cultures. In medium of normal osmolarity, putrescine and spermidine both allow sustained rapid growth for many hours. In low osmolarity medium, putrescine allows sustained rapid growth, whereas cultures containing spermidine grow more slowly; this result cannot be explained by conversion of putrescine to spermidine, for cultures grown with exogenous putrescine contain smaller spermidine pools than do cultures grown with exogenous spermidine. Spermine greatly stimulates growth in medium of normal osmolarity; however, in medium of low osmolarity, spermine is much less effective and can block the action of putrescine. Several other polyamines have been studied in this system. These results confirm and expand previous reports that polyamines are necessary for growth of E. coli and suggest that putrescine may have a specific function during growth in media of low osmolarity.

Arginine↗
PubMed1973

Effects of external osmolarity on phospholipid metabolism in Escherichia coli B.

The turnover of total [(32)P]phospholipids in Escherichia coli B is shown to be inversely related to the osmolarity of the medium and a reflection of the rates of turnover of the major phospholipid classes, phosphatidylglycerol and phosphatidylethanolamine. External osmolarity also affects the phosphatidylglycerol content of the culture. These results suggest that alterations in the metabolism of membrane phospholipids may be part of the process of adaptation to the external osmotic environment.

Adaptation, Biological↗
PubMedDate not supplied

Matuhasi-Ogata phenomenon involving anti-ampicillin.

A 47-year-old group A, Rh1Rh1 woman treated with intravenous ampicillin for chronic pyelonephritis received two units of blood and also received oral cephalexin. Three months after the transfusions she was noted to have allo-anti-E and anti-c, and a 2+ positive direct antiglobulin test. Anti-E and anti-c could be eluted from her cells, yet neither antigen could be demonstrated on the patient's circulating red blood cells. Also present in the serum and in the eluate was anti-ampicillin antibody. Studies of the patient's red blood cell eluates using ampicillin-treated R1R1 and untreated R2R2 cells demonstrated anti-E complexed with anti-ampicillin in a drug-related example of the Matuhasi-Ogata phenomenon. Artificially created mixtures of anti-E and drug antibody could reproduce the effect in vitro. No effect of cephalexin could be demonstrated. The variability of the Matuhasi-Ogata phenomenon is discussed with regard to the sequence of antibody attachment, and the possible relationship to cephalexin is discussed. Drug antibodies may be involved in the Matuhasi-Ogata phenomenon in cases where another red blood cell antibody cannot be shown to be present.

Ampicillin↗
PubMedDate not supplied

Further studies on the relationship of anti-Ena and anti-Wrb in warm autoimmune hemolytic anemia.

The red blood cell eluates of two patients with warm autoimmune hemolytic anemia (AIHA) were found to have anti-dl and anti-Wrb in a study of 150 individuals with positive AHG tests.7 In that series 39 per cent of AIHA cases had anti-Wrb as part of the autoantibody specificity. The eluates of these two patients were of further interest since they showed weaker reactions with En(a-) cells than with En(a+), Wr(a+b-) cells. Further absorption of the eluates confirmed a second component that reacted with the En(a+), Wr(b-) cells but not the En(a-) cell, interpreted as autoanti-Ena. In one of the cases anti-Ena was recovered from the En(a-) absorbing cell although these cells were not agglutinated by the autoantibody. This effect was not due to polyagglutinability, the Matuhasi-Ogata phenomenon or the decreased sialic acid content of the En(a-) red blood cell membranes and remains unexplained.

Absorption↗