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Biomedical subjects

R E Jordan

Publications and source records attributed to R E Jordan.

At least 55 records · Page 3Linked to original sources
PubMed1987

Heparin promotes the inactivation of antithrombin by neutrophil elastase.

Heparin is an acceleratory cofactor for antithrombin, a circulating inhibitor of blood coagulation enzymes. The presence of heparin on blood vessel walls is believed to contribute to the nonthrombogenic properties of those surfaces. In apparent opposition to this function, heparin was found to greatly accelerate the in vitro inactivation of antithrombin by neutrophil elastase. Inactivation rates in solution were potentiated several hundredfold by specific heparin fractions with anticoagulant activity. Although the data suggest that a heparin-antithrombin complex is essential for the inactivation by elastase to occur, the enzyme itself interacts tightly with heparin. These results suggest a mechanism which, if operating in vivo, could lead to a localized neutralization of the anticoagulant function of heparin at the endothelial surface.

Antithrombin III↗
PubMed1987

Physiological variant of antithrombin-III lacks carbohydrate sidechain at Asn 135.

Both normal antithrombin-III (AT-III alpha) and the high heparin affinity form (AT-III beta) were isolated from pooled human plasma. AT-III beta had a lower negative charge and lower molecular mass than AT-III alpha. Sialidase and endo-F digestion indicated that the inherent difference resided in the oligosaccharide component of the molecule. CNBr fragmentation showed there was an oligosaccharide sidechain missing between residues 104 and 251, subdigestion with trypsin indicated that Asn 135 was not glycosylated in AT-III beta. Chromatography of total tryptic digests on concanavalin A-Sepharose confirmed that the high heparin affinity form of antithrombin lacked an oligosaccharide moiety at Asn 135.

Antithrombin III↗
PubMed1986

Anticoagulantly active heparin from clam (Mercenaria mercenaria).

Heparin was isolated from Mercenaria mercenaria by ion-exchange chromatography and was fractionated into two distinct populations with immobilized antithrombin. The high-affinity glycosaminoglycan accelerated dramatically the inhibition of purified human factors IIa and Xa via purified human antithrombin. Specific anti-factor IIa and anti-factor Xa activities were 363 and 348 U.S.P. units/mg, respectively. The highly active clam heparin exhibited a molecular weight of approximately 18,000 and contained approximately 2.5 sulfate groups per disaccharide. The intrinsic fluorescence of purified human antithrombin was enhanced in the presence of the high-affinity invertebrate glycosaminoglycan to an extent comparable to the level induced by vertebrate heparin. In addition, the critical tetrasaccharides containing 3-O-sulfated glucosamine residues, which constitute part of the unique antithrombin-binding domain of mammalian heparin, were also detected in high-affinity Mercenaria heparin.

Animals↗
PubMed1986

Bonding to porcelain and gold.

To test the effectiveness of bonding orthodontic attachments to porcelain, edgewise brackets were bonded to 160 lower incisor, porcelain denture teeth by means of two different resin systems and three different porcelain bonding agents. Bonding to porcelain was found to be not only effective, but the use of a porcelain primer before bonding resulted in shear strengths comparable to those achieved with conventional acid-etch enamel bonding when the same resin was used. Roughening the porcelain surface and bonding with a heavily filled resin without a porcelain primer provided shear strengths (30.6 lbs) comparable to conventional acid-etch enamel bonding with a lightly filled resin (28.8 lbs). Roughening the porcelain surface before bonding, adding porcelain primers, and using highly filled resins all added significantly to bond strength, but caused a progressively greater risk of porcelain fracture during debonding. One of three methods to polish porcelain completely restored a roughened porcelain surface to its former appearance. The porcelain bonding primers failed to provide a significant increase in bond strength when bonding to gold. However, a roughened gold surface bonded with a heavily filled resin provided shear strengths (27.3 lbs). comparable to conventional acid-etch enamel bonding by means of a lightly filled resin (28.8 lbs). The use of a highly filled resin on an intact, glazed porcelain surface without using a porcelain primer may provide sufficient bond strength clinically. If more bond strength is needed, the use of Reliance porcelain primer on an intact glaze is preferable to Ormco porcelain primer or Fusion. Still greater bond strength can be developed by roughening the porcelain surface before application of a primer and use of a highly filled resin. The potential for porcelain fracture in debonding, however, is much increased and it is questionable whether bond strengths of this magnitude are required clinically.

Bisphenol A-Glycidyl Methacrylate↗
PubMed1986

A visible light-cured posterior composite resin: results of a 3-year clinical evaluation.

Seventy-nine Class I and II light-cured composite resin restorations were evaluated for 3 years. Although the composite resin was not totally wear resistant, its overall clinical performance was acceptable, relative to most parameters of evaluation. The use of such a material in the posterior region may be justified in situations in which appearance is important, ideal circumstances predominate over conservative cavity design, and the patient understands the benefits and limitations of the procedure.

Bicuspid↗
PubMed1985

Remission in skin infiltrate of a patient with mycosis fungoides treated with cyclosporine.

A 57-year-old woman with mycosis fungoides that had failed to respond to cytotoxic chemotherapy was treated with cyclosporine. Mycosis fungoides and Sézary syndrome are disorders of helper T cells. Cyclosporine is a fungal endecapeptide of novel chemical structure that causes preferential inhibition of T helper cells. Because of this in vitro inhibition of T helper cells, we used cyclosporine to treat a patient who had mycosis fungoides that was refractory to cytotoxic combination chemotherapy. With cyclosporine administered initially as an intravenous infusion and orally after 10 days, there was immediate improvement in the patient's symptoms. This subjective improvement was accompanied by a decrease in her skin infiltration, noted on physical examination and microscopically. Despite continued administration of the cyclosporine, symptoms recurred after 3 1/2 months of therapy.

Cyclosporins↗
PubMed1985

The new generation amalgam alloys. Clinical considerations.

There is a good deal of current speculation that composite resin materials will shortly replace silver amalgam as routine posterior restoration systems. This article provides guidelines in the selection and clinical handling of the new generation high copper amalgam alloys.

Chemical Phenomena↗
PubMed1983

Antithrombin in vertebrate species: conservation of the heparin-dependent anticoagulant mechanism.

Heparin is thought to regulate the rate of mammalian blood clotting by enhancing the activity of antithrombin, an inhibitor of coagulation enzymes. The present study establishes that this same inhibitor is present in the blood plasma of each of the terrestrial vertebrate groups including mammals, birds, reptiles, and amphibians. In each case, an inhibitor with remarkably similar properties to human antithrombin was isolated by affinity chromatography on immobilized porcine heparin. The purified vertebrate inhibitors all show the following physical and functional homologies to human antithrombin: (i) heparin-enhanced inhibition of both bovine thrombin and human Factor Xa, (ii) molecular masses of approximately 60,000, and (iii) heparin-induced increases in ultraviolet fluorescence. Also, the heparin-binding interaction of vertebrate antithrombins is highly selective with each demonstrating the same rigid specificity for heparin species fractionated on the basis of their affinity for human antithrombin. This common ability of vertebrate antithrombins to discriminate among heparins is accomplished by a nearly unvarying equilibrium binding constant for the high-affinity heparin species. Thus, the present results suggest that the anticoagulant relationship of heparin and antithrombin was established at an early point in the evolution of the coagulation system and has been highly conserved since that time.

Animals↗