Clinical evaluation of the BTA TRAK assay and comparison to voided urine cytology and the Bard BTA test in patients with recurrent bladder tumors. The Multi Center Study Group.

OBJECTIVES: To assess the clinical performance of the BTA TRAK assay and to compare it with that of voided urine cytology (VUC) and the Bard BTA test (BTA) in the detection of recurrent bladder cancer (BC). METHODS: The study was performed on randomly selected archival voided urine samples for many of which VUC and/or BTA information was available. Sensitivity was determined in samples from patients with histologically confirmed recurrent BC. Specificity was determined in samples from healthy volunteers, patients with three categories of current medical conditions, and patients with a history of BC but no current evidence of disease. RESULTS: The TRAK assay was positive in 156 of 216 samples for patients diagnosed with BC, for an overall sensitivity of 72%. Mean values increased with progressing grade and stage of disease. In the comparison between TRAK and VUC, the overall sensitivities were 68% and 25%, respectively (P < 0.001). For Stages Ta and T1 and for all tumor grades, the sensitivity of the TRAK assay was significantly greater than that of VUC (P < 0.001). TRAK sensitivity was also significantly better than that of BTA (73% versus 58%, P = 0.005). The specificity of the TRAK assay ranged from 75% in samples from patients with genitourinary disease to 97% in healthy volunteers. CONCLUSIONS: The TRAK assay is superior to VUC and the original BTA test in the detection of BC. The results of the study indicate that the TRAK assay may be a useful adjunct to cystoscopy in the management of patients with recurrent BC.

Cleavage and activation of human factor IX by serine proteases.

Human factor IX circulates as a single-chain glycoprotein. Upon activation in vitro, it is cleaved into disulfide-linked light and heavy chains and an activation peptide. After reduction of activated 125I-factor IX, the heavy and light chains are readily identified by gel electrophoresis. A direct, immunoradiometric assay for factor IXa was developed to assess activation of factor IX for proteases that cleaved it. The assay utilized radiolabeled antithrombin III with heparin to identify the active site and antibodies to distinguish factor IX. After cleavage of factor IX by factor XIa, factor VIIa-tissue thromboplastin complex, or the factor X-activating enzyme from Russell's viper venom, antithrombin III bound readily to factor IXa. Cleavage of 125I-factor IX by trypsin, chymotrypsin, and granulocyte elastase in the presence of calcium yielded major polypeptide fragments of the sizes of the factor XIa-generated light and heavy chains. Kallikrein did not cleave the zymogen. Nonactivation cleavage was noted by thrombin, but only in the absence of calcium. When the immunoradiometric assay was used to assess trypsin-cleaved factor IX, the product bound antithrombin III, but not maximally. After digesting with insolubilized trypsin, clotting activity confirmed activation. In contrast, incubation of factor IX with elastase (Takaki A et al, J Clin Invest 71:1706, 1983) or chymotrypsin did not lead to generation of an antithrombin III-binding site, despite their digestion of 125I-factor IX into heavy and light chain-sized fragments. In evaluating activation of factor IX, physical evidence of activation cleavages does not necessarily correlate with generation of an active site.

Cleavage and inactivation of Factor IX by granulocyte elastase.

Radioiodinated Factor IX was cleaved by a crude sonicate from leukocytes. In the absence of calcium, fragments of less than 15,000 mol wt were seen from reduced samples on gel electrophoresis. After digestion in 2 mM calcium, however, electrophoresis of reduced samples showed, in addition to low molecular weight fragments, protein bands corresponding in size to heavy and light chains of Factor XIa-activated Factor IX. The cleaving activity in leukocyte sonicates was inhibited by soybean trypsin inhibitor, but only to a small extent by aprotinin. Granulocyte elastase was isolated from purified polymorphonuclear leukocyte granules by affinity chromatography on soybean trypsin inhibitor-agarose and further chromatography on carboxymethyl cellulose. The purified fraction contained two isozymes on acidic gels which cleaved both an ester sensitive to elastase and radiolabeled Factor IX. These two activities were inhibited by elastase-specific chloromethyl ketone. The isolated protease fraction rapidly inactivated apparent Factor IX activity in a coagulant assay system. The degree of inactivation correlated with the amount of intact, radiolabeled Factor IX cleaved. As with the crude sonicate, generation of the larger heavy and light chain-sized fragments was dependent upon calcium. To assess directly the effect of elastase on Factor IX, an immunospecific, active site-directed assay was developed. In this assay, the sample was incubated with solid-phase antibody to Factor IX and the amount of activated product was detected as that which had complexed with radioiodinated antithrombin III. In this system, exposure of Factor IX to Factor XIa showed progressive increase in the ability to bind antithrombin III, whereas after elastase, Factor XIa was unable to generate antithrombin III binding. The elastase-degraded Factor IX did not inhibit activation of additional Factor IX in clotting assays. When Factor IXa was incubated with elastase, binding of antithrombin III was decreased, corresponding to appearance of low molecular weight fragments on parallel samples that were reduced and electrophoresed. These data are consistent with elastase inactivating Factor IX by cleaving bonds near, but distinct from, bonds cleaved by Factor XIa.

Amino acid sequence of the light chain of bovine factor X1 (Stuart factor).

The detailed proof of the amino acid sequence of the 140 residues (16,193 daltons) of the light chain of bovine factor X1 (Stuart factor) is presented. Sequence analyses were performed on fragments obtained after chemical cleavage of asparagine-glycine and tryptophanyl peptide bonds and after various enzymatic digestion procedures. Twelve gamma-carboxyglutamyl residues are clustered in the amino-terminal 39 residues and 13 half-cystine residues are found in the carboxyl-terminal 91 residues, suggesting two domains in the light chain, one exceptionally anionic and the other extensively cross-linked by disulfides.

Comparison of amino acid sequence of bovine coagulation Factor IX (Christmas Factor) with that of other vitamin K-dependent plasma proteins.

The amino acid sequence of bovine blood coagulation Factor IX (Christmas Factor) is presented and compared with the sequences of other vitamin K-dependent plasma proteins and pancreatic trypsinogen. The 416-residue sequence of Factor IX was determined largely by automated Edman degradation of two large segments, containing 181 and 235 residues, isolated after activating Factor IX with a protease from Russell's viper venom. Subfragments of the two segments were produced by enzymatic digestion and by chemical cleavage of methionyl, tryptophyl, and asparaginyl-glycyl bonds. Comparison of the amino acid sequences of Factor IX, Factor X, and Protein C demonstrates that they are homologous throughout. Their homology with prothrombin, however, is restricted to the amino-terminal region, which is rich in gamma-carboxyglutamic acid, and the carboxyl-terminal region, which represents the catalytic domain of these proteins and corresponds to that of pancreatic serine proteases.

Crayfish carboxypeptidase. Affinity chromatography, characterization and amino-terminal sequence.

In an effort to trace the evolutionary history of the pancreatic metalloexopeptidases, carboxypeptidase has been isolated from the cardia of the crayfish Astacus fluviatilis. The isolation procedure included affinity chromatography on a column of potato carboxypeptidase inhibitor covalently linked to Sepharose. Approximately 25 mg of pure enzyme can be obtained by the present procedure from 50 ml of cardia fluid. The pure enzyme resembles bovine carboxypeptidase B in specificity and is inhibited both by 3-phenyllactate and by 6-aminohexanoate. The pH optimum of activity is about pH 6.5, and the isoelectric point,pH 4.0. Inhibition by typical metal chelating agents (i.e. ethylenediamine tetraacetate and 1,10-phenanthroline) and neutron activation analysis indicate that, like the mammalian enzyme, crayfish carboxypepetidase is a zinc metalloenzyme. The purified enzyme migrates as a single band in cellulose acetate, disc gel and sodium dodecylsulfate gel electrophoresis. The amino acid composition is similar to that of pancreatic carboxypeptidases except for a higher content of acidic amino acid residues. The amino acid sequence of the first 19 amino-terminal residues reveals significant homology to that of pancreatic carboxypeptidases A and B.

Bovine factor X1 (Stuart factor): amino-acid sequence of heavey chain.

The amino-acid sequence of the heavy chain of bovine blood coagulation factor X1 (Stuart factor) isolated before and after activation has been determined. Sequence analysis was performed on fragments obtained by cleavage with cyanogen bromide and by tryptic digestion. Comparison of the complete sequence with those of other hepatic and pancreatic serine proteases demonstrates homology of the heavy chain of activated factor X1 (factor X1a) with the B chain of bovine thrombin as well as with bovine trypsin, chymotrypsins A and B, and porcine elastase. The activation peptide cleaved near the amino terminus by a protease from Russell's viper venom differs in both size and sequence from those of other serine proteases. With three exceptions, all of the residues which are important in the catalytic functions of trypsin and chymotrypsin occur in corresponding loci in the heavy chain of factor Xa. These finding suggest that the three-dimensional structure of the heavy chain is similar to that of the pancreatic serine proteases and that these enzymes have evolved from a common ancestral gene.

Amino-acid sequence of parvalbumin from rabbit skeletal muscle.

Determination of the complete amino-acid sequence of rabbit skeletal muscle parvalbumin is described. The sequence of 86 of the 109 total residues was determined automatically by sequenator analyses of peptides obtained after cleavage with CNBr or with trypsin. The positions of the remaining 23 residues were determined by subtractive Edman degradation of tryptic and chymotryptic peptides. The protein has an acetylated amino terminus. Comparison of the rabbit parvalbumin with those from carp, hake, and pike and with the calcium binding subunit of rabbit muscle troponin indicates that these proteins are homologous. Among the parvalbumins a high degree of identity is observed, especially of residues involved in the binding of calcium or in the formation of the hydrophobic core.

Bovine factor X1 (Stuart factor). Primary structure of the light chain.

The amino-acid sequence of the light chain of bovine factor X1 is presented. The sequence of 112 of the 140 residues was determined automatically on fragments produced by specific cleavage of arginyl, glutamyl, tryptophanyl, and asparaginyl-glycine bonds. The remainder was determined by conventional procedures. The amino-terminal sequence of the light chain is homologous with the amino-terminal region of bovine prothrombin and, like the latter, appears to contain several residues of a recently discovered unusual amino acid, lambda-carboxy-glutamic acid. The role of this amino acid in the calcium-binding ability of factor X and prothrombin is discussed.

A comparison of bovine prothrombin, factor IX (Christmas factor), and factor X (Stuart factor).

A comparison has been made of the electrophoretic behavior, chemical composition, amino-terminal sequence, and immunological properties of bovine prothrombin, factor IX (Christmas factor), and factor X (Stuart factor). Some immunological crossreactivity was found between the antibody to prothrombin and factor X although prothrombin and factor X differ substantially in amino-acid and carbohydrate composition. Considerable amino-acid sequence homology was found in the amino-terminal portion of prothrombin, factor IX, and the light chain of factor X. These data provide further evidence to support the hypothesis that at least three of the vitamin K-dependent clotting factors have evolved from a common ancestral gene.