Bronchoalveolar lavage (BAL) in newly diagnosed patients with collagen vascular diseases.

Collagen vascular diseases (CVD) are commonly associated with interstitial lung diseases. Bronchoalveolar lavage (BAL) fluid analysis has important diagnostic value when considered in conjunction with other information. The present study was undertaken in newly diagnosed patients with systemic lupus erythematosus (SLE) and rheumatoid arthritis (RA) at presentation to characterise BAL cellular constituents and elucidate the cellular picture in patients with and without pulmonary symptoms and in those with and without radiological (high resolution computed tomography) features of interstitial lung disease. All the patients were non-smokers and had not received any form of treatment for their diseases. The means of percentages of lymphocytes, neutrophils, and macrophages were 23.3%, 6.2%, 70.5% respectively. There was a significant BAL lymphocyte predominance in patients with pulmonary symptoms, and a lymphocyte and neutrophil predominance in those having radiological evidence of interstitial lung disease.

Transglutaminase inhibition by 2-[(2-oxopropyl)thio]imidazolium derivatives: mechanism of factor XIIIa inactivation.

The physiologic role of several transglutaminases could be more precisely defined with the development of specific inhibitors for these enzymes. In addition, specific plasma transglutaminase (fXIIIa) inhibitors may have therapeutic utility in the treatment of thrombosis. For these purposes, the inactivation of fXIIIa and human erythrocyte transglutaminase (HET) by 2-[(2-oxopropyl)thio]imidazolium derivatives, which comprise a novel class of transglutaminase inactivators, was studied. As a specific example, 1,3,4,5-tetramethyl-2-[(2-oxopropyl)thio]imidazolium chloride (III) inactivated fXIIIa with an apparent second-order rate constant (specificity constant of inactivation) of 6.3 x 10(4) M-1 s-1, corresponding to a rate 4 x 10(7) times greater than its reaction rate with glutathione (GSH). The mechanism of fXIIIa inactivation by this class of compounds was investigated utilizing two [14C]-isotopic regioisomers of 1,3-dimethyl-2-[(2-oxopropyl)thio]imidazolium iodide (II). Structural analyses demonstrated that acetonylation of the active site cysteinyl residue of fXIIIa occurred along with the stoichiometric release of the complementary fragment of the inactivator as the corresponding thione. Kinetic analysis of the inactivation of fXIIIa by nonquarternary analogs of II and III indicated the formation of a reversible complex between the inactivator and fXIIIa prior to irreversible modification of the enzyme. At 1 mM, III displayed no detectable levels of inhibition or inactivation with several serine proteases and thiol reagent-sensitive enzymes. 2-[(2-Oxopropyl)thio]imidazolium derivatives and the related molecule 2-(1-acetonylthio)-5-methylthiazolo-[2,3]-1,3,4-thiadiazo lium perchlorate (I), when present at the time of clot formation at 1-10 microM, enhanced the rates of tissue plasminogen activator catalyzed clot lysis in vitro. These inactivators prevented the fXIIIa-catalyzed covalent incorporation of alpha 2-antiplasmin into the alpha chain of fibrin and the formation of high molecular weight fibrin alpha chain polymers, providing the basis for the observed enhancements in clot lysis rates.

Identification and characterization of endothelin converting activity from EAHY 926 cells: evidence for the physiologically relevant human enzyme.

A neutral proteolytic activity that converts human Big endothelin-1 (Big Et-1) to endothelin-1 has been identified from a human endothelial hybrid cell line, EAHY 926. This enzyme is an integral membrane protein and cofractionates with other enzymes typically found in the plasma membrane. The activity has been solubilized with nonionic detergents and purified 1000-fold by a combination of lectin affinity chromatography, ion-exchange chromatography, and chromatography on red-dye agarose. The partially purified activity is a metalloenzyme based upon its sensitivity to chelating agents, competitive inhibition by phosphoramidon, and reconstitution with ZnCl2 or CoCl2 following EDTA inactivation. The enzyme appears to be unique, however, as it is not inhibited by specific inhibitors of known metalloproteases. It correctly processes Big Et-1 to Et-1 and the complementary C-terminal fragment with a sharp pH optimum near 7.0. Both the Km for Big Et-1 and the Ki for phosphoramidon are pH-dependent, with values of 5-7 and 3.5 microM, respectively, at pH 7.0. The enzyme also cleaves Big Et-2 with a Km of 27.9 microM and a Vmax one-third that for Big Et-1 but has no appreciable activity toward Big Et-3. An s20,w of 9.5 S was determined by sucrose density ultracentrifugation in H2O and D2O. When combined with a Stokes radius of 56 A determined by gel filtration, the enzyme had a calculated apparent molecular weight of 250,000. Conditions have been established to renature the activity after sodium dodecyl sulfate-polyacrylamide gel electrophoresis. Under nonreducing conditions activity was detected in a protein band at 280 kDa, in agreement with the aforementioned molecular weight determination. From these results, a kcat/Km of 1 x 10(6) M-1 s-1 was estimated for the purified enzyme with Big Et-1 as a substrate, which is a reasonable value for a protease acting upon its physiologic substrate. Several criteria indicate that the activity isolated from EAHY cells is the physiologically relevant endothelial-derived endothelin converting enzyme. On the basis of our results, this enzyme is present in low abundance in endothelial cells and at least a 100,000-fold purification will be required to obtain a homogeneous preparation. However, because EAHY cells can be grown in large numbers, they can supply the quantities of enzyme required both for biochemical studies and for the development of specific inhibitors.