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Biomedical subjects

E Black

Publications and source records attributed to E Black.

At least 55 records · Page 3Linked to original sources
PubMed1985

Analysis of chromatin changes associated with the expression of globin and non-globin genes in cell hybrids between erythroid and other cells.

Red blood cell differentiation involves the coordinate expression of a set of polypeptides some of which are erythroid-specific (the abundant globins as well as minor species such as glycophorin, carbonic anhydrase I and the RBC lipoxygenase) whereas others are found also in a subset of other cells, e.g. beta spectrin and a 19 kd polypeptide (ep 19) found in adult liver and kidney as well as erythroid cells. To investigate the genetic mechanisms involved in the regulation of these classes of genes, the expression of lipoxygenase, ep 19 and beta globin mRNAs was investigated in cell hybrids between mouse erythroid (Friend) cells and mouse T-lymphoma or neuroblastoma cells. All three mRNAs are expressed or repressed together in cell hybrids between the Friend cell and lymphoma or neuroblastoma cells respectively. Moreover, studies of the chromatin structure surrounding the genes reveal that erythroid cell-specific DNaseI hypersensitive sites within the ep 19 and beta major globin genes are lost in the Friend cell X neuroblastoma hybrids whereas they are retained in the Friend cell X lymphoma cell hybrids. This implies that the trans-acting mechanism responsible for regulating the RBC phenotype in these cell hybrids acts at the level of the early chromatin changes thought to reflect a pre-activation stage in gene expression.

Animals↗
PubMed1984

Neutralization of croatalidae venom induced platelet aggregation by affinity chromatography isolated IgG to Crotalus viridis helleri venom.

IgG was isolated from commercial antivenin by affinity chromatography using Crotalus viridis helleri venom as an affinant. This purified IgG was demonstrated to be more effective than the commercial antivenin in preventing platelet aggregation induced by four separate crotalid venoms in vitro. Affinity chromatography appears to be an effective means for specific, polyvalent IgG isolation and purification.

Animals↗
PubMed1975

Hepatic albumin and urea synthesis: The mathematical modelling of the dynamics of [14C]carbonate-derived guanidine-labelled arginine in the isolated perfused rat liver.

A mathematical model was constructed to define the dynamics of incorporation of radioactivity into urea carbon and the guanidine carbon of arginine in plasma albumin after the rapid intraportal-venous administration of Na214CO3 in the isolated perfused rat liver. 2. The model was formulated in terms of compartmental analysis and additional experiments were designed to provide further information on subsystem dynamics and to discriminate between alternative model structures. 3. Evidence for the rapid-time-constant of labelling of intracellular arginine was provided by precursor-product analysis of precursor [14C]carboante and product [14C]urea in the perfusate. 4. Compartmental analysis of the dynamics of newly synthesized urea was based on the fate of exogenous [13C]urea, endogenous [14C]urea and the accumulation of [12C]urea in perfusate water, confirming the early completion of urea carbon labelling, the absence of continuing synthesis of labelled urea, and the presence of a small intrahepatic urea-delay pool. 5. Analysis of the perfusate dynamics of endogenously synthesized and exogenously administered [6-14C]arginine indicated that although the capacity for extrahepatic formation of [14C]-urea exists, little or no arginine formed within the intrahepatic urea cycle was transported out of the liver. However, the presence of a rapidly turning-over intrahepatic arginine pool was confirmed. 6. On the basis of these subsystem analyses it was possible to offer feasible estimations for the parameters of the mathematical model. However, it was not possible to stimulate the form and magnitude of the dynamics of newly synthesized labelled urea and albumin which were simultaneously observed after administration of [14C]carbonate on the basis of a preliminary model which postulated that both products were derived from a single hepatic pool of [16-14C]arginine. On the other hand these observed dynamics could be satisfied to a two-compartment arginine model, which also provided an explanation for discrepancies observed between albumin synthesis measured radioisotopically and immunologically. This was based on a relative overestimation of [14C]urea specific radioactivity resulting from the rapid dynamics of [14C]carbonate and the [14C]urea subsystem relative to the labelled albumin subsystem. The effects of arginine compartmentalization could be minimized in the model by minor slowing of the rate of [14C]carbonate turnover or by constant infusion of [14C]carbonate, both of which permitted valid determination of albumin-synthesis rates.

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