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J Elion

Publications and source records attributed to J Elion.

At least 163 records · Page 9Linked to original sources
PubMed1985

Production of monoclonal antibodies to the high fibrin-affinity, tissue-type plasminogen activator of human plasma. Demonstration of its endothelial origin by immunolocalization.

Monoclonal antibodies (MAbs) to vascular plasminogen activator (vPA), the tissue-type plasminogen activator (tPA) in human plasma, were produced to be used as probes for immunochemical analysis. Human tissue sections and one of these MAbs were used to demonstrate the endothelial origin of plasma-tPA by immunohistochemistry. To produce MAbs, mice were immunized with semipurified vPA isolated from postocclusion human venous blood. Primed spleen cells were fused with the mouse myeloma cell line NS-1. Screening for MAb-producing hybridomas was performed with postocclusion euglobulins as a source of antigen by means of a solid-phase fibrin-vPA immunoassay. The selective and high-affinity binding of vPA for fibrin ensures the specificity and sensitivity of this test. Thus, eight hybridomas secreting MAbs to vPA were selected, cloned, and established as permanent hybridoma cell lines. Immunohistochemical analysis of cryostat sections of human tissues was performed with EA-delta 12D, a MAb having no inhibitory effect against vPA activity but binding to vPA with a high affinity. Thus, the only structures immunostained were endothelial cells of venules, capillaries, and arterioles. The EA-delta 12D monoclonal localization of plasma vPA in the endothelial lining of blood vessels provides evidence that tPA in plasma originates from the vascular wall and validates its designation as vascular plasminogen activator, ie, vPA. Also, our results are consistent with the fact that vPA in blood and tPA in tissues are immunologically identical and have a common endothelial origin.

Antibodies, Monoclonal↗
PubMed1984

Covalent structures of beta and gamma autolytic derivatives of human alpha-thrombin.

Nonclotting beta- and gamma-thrombins have been prepared by autolysis of human alpha-thrombin at pH 8.6 in the presence of 0.4 M NaCl and purified on BioRex 70. Reduced and carbamidomethylated A and B chains fragments were separated by gel filtration and reverse phase high performance liquid chromatography. Structural characterization of these fragments demonstrated that alpha to beta conversion results from two cleavages at Arg 62 and Arg 73 in the B chain, releasing an intact 11-residue peptide. beta to gamma conversion corresponds to the additional loss of a fragment of the B chain stretching from Ile 124 to Lys 154. Autolysis is not accompanied by cleavages in the A chain. Loss of clotting activity is therefore related solely to the excision of residues 63 to 73 in the B chain. With the exception of cleavage at Arg 73, these results differ from a proposed model for alpha to gamma conversion of bovine thrombin.

Amino Acid Sequence↗
PubMed1984

Haemoglobinopathies: a pitfall in the assessment of glycosylated haemoglobin by ion-exchange chromatography.

Total glycosylated haemoglobin was determined by a minicolumn ion-exchange chromatography technique (Bio-Rad) and correlated with the mean of fasting and post-prandial blood glucose values for the preceding 6 weeks. In 360 diabetic subjects, free of congenital haemoglobinopathies and other detected causes of haemoglobin A1 misinterpretation (reference diabetic group), a highly significant correlation was established between haemoglobin A1 and glucose (y = 0.54 X +4.91; r = 0.791; p less than 0.01). In 28 of the 29 patients with heterozygous haemoglobinopathies (HbS, C, D, E), the apparent haemoglobin A1 values were lower than expected according to the 95% confidence limits of the diabetic reference group. The apparent haemoglobin A1 value was above these limits in patient 29, with beta thalassaemia. Patients with inappropriate glycosylated haemoglobin values should be investigated for causes of haemoglobin A1 misinterpretation, in particular, haemoglobinopathies.

Blood Glucose↗
PubMed1984

Haemoglobinopathies, malaria, and other interferences with HBA1 assessment.

Total glycosylated haemoglobin (HbA1) was determined by a rapid minicolumn chromatography technique in 438 diabetic patients and correlated with the mean of fasting and post-prandial blood glucose values for the preceding six weeks. In 360 of them, free of congenital haemoglobinopathies and other detected causes of HbA1 mis-interpretation (reference group), a significant correlation was established between the HbA1 and glucose values: y = 0.54 X + 4.91; r = 791; (p less than 0.01). In 28 of the 29 patients with heterozygous haemoglobinopathies (Hb S = 17; Hb C = 8; Hb D Pundjab = 1; Hb E = 2) the apparent HbA1 values were inappropriately low. The apparent HbA1 value was above the 95% confidence limits in the 29th patient, with beta thalassaemia. In 10 out of 14 diabetics with recurrent hypoglycemic attacks, the HbA1 value was lower than the 95% confidence limits of expected values. Out of 21 diabetics with a shortened red cell lifespan (occult blood losses: 10; haemolysis: 11) 15 displayed a lower than expected HbA1 value. Among these was a diabetic patient with malaria and severe anaemia. Out of 14 diabetics with severe chronic renal failure only 3 presented with apparent HbA1 values above the 95% confidence limits.

Adult↗
PubMed1984

Thrombin Metz: characterization of the dysfunctional thrombin derived from a variant of human prothrombin.

Thrombin Metz and normal thrombin, resulting from activation of the respective prothrombins by factor Xa in the presence of calcium, phospholipid, and factor Va, were purified by chromatography on sulfopropyl Sephadex. By physicochemical criteria, thrombin Metz is identical to normal thrombin. Its functional properties were investigated in some reactions in which thrombin is classically involved. Thrombin Metz exhibits less than 4% of fibrinogen clotting activity. Both Km and Kcat, determined on S2238, are abnormal. Titration with the high-affinity competitive inhibitor of thrombin, DAPA, shows that fluorescence enhancement of the probe is only 34% in binding to thrombin Metz when compared to that observed in binding to normal thrombin. High-performance liquid chromatography has been used to measure the simultaneous rate of release of fibrinopeptides A and B. A decreased release rate for both fibrinopeptides, more marked for fibrinopeptide B, results in a slow fibrin polymerization, as followed by absorbance at 450 nm. Thrombin Metz is less than 5% as effective as normal thrombin in inducing platelet aggregation. Interaction with antithrombin III is slower than normal when followed by SDS gel electrophoresis and inhibition of the amidolytic activity of thrombin on S2238. This abnormality is not observed in the presence of heparin. However, thrombin Metz binds less tightly to a heparin-Sepharose column, and the direct inhibition of heparin on its activity on S2238 is weaker. From these results, we can predict that the defect in thrombin Metz affects the catalytic site or its vicinity and, jointly or consequently, the region of interaction of thrombin with antithrombin III and heparin.

Antithrombin III↗
PubMed1983

Monosaccharides bound to hemoglobins in normal and diabetic individuals. Evidence for glucose, mannose and galactose as sugars released by methanolysis of the different hemoglobin components.

Direct evidence is given for the presence of glucose, mannose and galactose as the products of hydrolysis of hemoglobins A1a1, A1a2, A1b, A1c and A0. The presence of galactose cannot be explained by the earlier hypothesis of Amadori rearrangement and suggests the existence of further complex rearrangements. Monosaccharide content of the different hemoglobin components varies from 0.2-2.0 mol/mol of alpha beta dimer with an increase of 1.5-2.0-times in diabetic components. This increase is not accompanied by net charge differences, suggesting that additionally bound sugars are not responsible for the pI modification of these hemoglobins. The pattern of glucose, mannose and galactose ratio in normal individuals divides these hemoglobins into two classes, hemoglobins A1b, A1c and A0 (ratio 0.60:0.25:0.15) on one hand and hemoglobins A1a1 and A1a2 (ratio 0.40:0.40: 0.20) on the other. These findings suggest that diverse mechanisms for sugar binding might exist between these two classes of glycosylated hemoglobins. This difference disappears in diabetic components suggesting that the non-NH2-terminal sites are glycosylated in all components by a common mechanism. Increase in glucose at the expense of mannose and galactose, as observed in diabetics, could be an indicator of recent glycosylation.

Blood Glucose↗
PubMed1983

Influence of thyroid status on hemoglobin A2 expression.

We studied the electrophoretic pattern of hemoglobin (Hb) and red blood cell indices in 128 women divided into four groups: group I, 36 nonanemic hyperthyroid women, divided in two subgroups: 36 with untreated hyperthyroidism (subgroup IA) and 9 made euthyroid by antithyroid drug therapy (subgroup IB); group II, 12 nonanemic women with untreated hypothyroidism; group III, 30 women known to be heterozygous for beta-thalassemia; and group IV, 50 healthy women. The mean (+/- SEM) HbA2 level was higher (P less than 0.001) in subgroup IA (3.21 +/- 0.06%) than in subgroup IB (2.42 +/- 0.09%) and group IV (2.48 +/- 0.04%), but lower (P less than 0.001) than in group III (5.26 +/- 0.12%). The mean HbA2 level was lower (P less than 0.001) in group II (1.99 +/- 0.08%) than in group IV. Hb fetal was detectable in eight patients of subgroup IA and undetectable in subgroup IB and groups II and IV. The mean cellular volume was lower (P less than 0.001) in subgroup IA than in other nonanemic groups. The mean cellular volume was higher (P less than 0.001) in group II than in group IV. Follow-up of nine patients who became euthyroid with treatment showed the normalization of these erythrocyte parameters. These results suggest that thyroid hormones can modulate the synthesis of delta- and gamma-globin chains.

Adult↗
PubMed1982

Homozygous deletional alpha + thalassaemia associated with unequal expression of the two remaining alpha 1 genes (alpha 1A and alpha 1Q).

A Cambodian family presenting several haemoglobinopathies, Hb E, Hb Q and alpha + thalassaemia, has been investigated. DNA analysis showed that the thalassaemia syndrome corresponds to a leftward type (4.2 kb) deletional form of alpha + thalassaemia. Genotypes found in the family are: propositus -alpha A/-alpha Q, beta A/beta E., mother and older sister alpha A alpha A/-alpha Q, beta A/beta E., father alpha A alpha A/-alpha A, beta A/beta A. The propositus consistently presents an alpha Q/alpha A chain ratio of 60/40 although both chains are products of alpha 1 loci. The relatively higher expression of the alpha Q chain is not observed in the mother and therefore makes it unlikely to reflect anything other than differential expression of the maternal -alpha Q/ and paternal -alpha A/ haplotypes. This observation raises the possibility that both haplotypes are not strictly identical and that the region of the cross-over event is important for alpha gene expression.

Chromosome Deletion↗
PubMed1981

Prothrombin.

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Amino Acid Sequence↗
PubMed1981

[Recent data concerning abnormal hemoglobins (author's transl)].

The study of abnormal hemoglobins was oriented towards three criteria as a function of commonly encountered clinical problems : differentiation between frequent, relatively infrequent and exceptional hemoglobins ; systematic study of high-risk ethnic groups and isolated discoveries ; silent hemoglobinopathies and those accompanied by physiopathological repercussions such as hemolytic anemia, disturbance in oxygen transport and cyanosis. The chronology and rationale for these studies was discussed, with particular attention being given both to normalized baseline measures and to the new, high-resolution techniques such as isoelectric focalization. No attempt was made to provide an exhaustive list, but rather examples were provided illustrating the various points considered. Finally, a number of particular points are brought up to where a correctly made diagnosis can avoid the necessity of subjecting patients to long and possibly dangerous tests.

Anemia, Hemolytic↗
PubMed1980

Interaction of prothrombin and its fragments with monolayers containing phosphatidylserine. 1. Binding of prothrombin and its fragment I to phosphatidylserine-containing monolayers.

The adsorption isotherms of prothrombin and its fragment I on phosphatidylserine monolayers and on mixed monolayers of phosphatidylcholine and phosphatidylserine were determined by measuring surface radioactivity emanating from the tritium-labeled absorbed proteins at 0.1 N NaCl and between 0 and 10 mM Ca2+. The proteins were absorbed from very dilute solutions, about 10 times more than in previous investigations on bilayer vesicles. The binding constants as obtained from the Scatchard plots were between 3 X 10(6) and 3 X 10(8) mol/L, depending on the experimental conditions. These values are between 2 and 50 times larger, respectively, than the binding constants obtained on bilayer vesicles. Prothrombin absorbs appreciably also in the absence of Ca2+. The significance of these results is discussed.

Adsorption↗