A novel chromogenic peptide for prekallikrein/kallikrein determination.

OBJECTIVE: To determine the Km, Vmax, and Ki of BOC-Leu-Ser-Thr-Arg-pNA (B3644) in the determination of kallikrein, and then to establish the procedure for plasma prekallikrein/kallikrein determination. Method Chromogenic substrate assays on a semi-auto spectrophotometer were employed. RESULTS: The apparent activities of seven substrates: B3644, S2238, S2251, ChromozymPCa, T6140, ChromozymPK, and T1637, for porcine kallikrein were 0.788, 0.691, 0.659, 0.636, 0.438, 0.396, and 0.145, respectively, that of B3644 being the highest. Amidolysis caused by kaolin activated human normal plasma was independent of coagulation factors II, X, XI, and protein C, but dependent on prekallikrein and to some extent on factor XII. The kallikrein's, thrombin's, and plasmin's Km and Vmax for the B3644 were determined and calculated to be 235 micromol/L and 337 nmol x s(-1) x U(-1), 469 micromol/L and 63 nmol x s(-1) x U(-1), and 70 micromol/L and 358 nmol x s(-1) x U(-1), respectively. At the same time, the kallikrein, thrombin, and plasmin Ki values for antithrombin III (AT-III) or limabean trypsin inhibitor (LBTI) were detected to be 840 or 2.50. 32 or 0.32, and, 108 or 1.55 U/L, [d1] respectively. With B3644, the recovery percentages of kallikrein and kaolin activated plasma were 100%. Intra-assay CV values ranged from 2.3% to 4.6%. By using B3644 and introducing AT-III or LBLI into the determination system, an optimized procedure for prekallikrein/kallikrein determination was obtained. With this procedure, the mean percentage values of plasma prekallikrein in normal subjects, pregnant women (gestation > or =24 weeks), and in patients with hypertension, hepatic failure, or with advanced cancers were determined to be 113.5, 151.6 (P<0.01), 173.2 (P<0.01), 43.5 (P<0.005), and 88.7 (P<0.05), respectively. CONCLUSION: B3644 was identified as a suitable substrate for the determination of plasma prekallkrein/kallikrein activity. A sensitive and reliable chromogenic substrate assay for human plasma prekallikrein was developed by using this novel substrate.

[Clinical observation of TP regiment for treating refractory and terminal squamous cancer of the esophagus].

OBJECTIVE: To evaluate the therapeutic efficacy and adverse effects of TP regimen consisting of taxol (TAX) and cisplatin (DDP) for treating refractory and terminal squamous cancer of the esophagus. METHODS: Totally 64 patients with stage IV squamous cancer of the esophagus, who failed to respond to a tow-course regiment, were treated with TP regimen with intravenous infusion of TAX 175 mg/m(2) on day 1 and DDP 30 mg/d on days 2-6. After 3 consecutive treatment course, each for 28 days, evaluation of the short-term efficacy and adverse effects was carried out. RESULTS: All the 64 patients completed altogether 192 treatment courses of TP regiment, resulting in a total response rate of 59.4% including 9 patients with complete remission (CR) and 29 with partial remission (PR). Stabilization (SD) was achieved in 12 patients while 14 failed to respond favorably and had further progression (PD) of the disease. The median remission duration was 4.8 months, median TTP 4.4 months and median survival of 9.8 months (4-28 months). The main adverse effect of the regimen was bone marrow depression. CONCLUSION: TP regimen for treating refractory and terminal squamous cancer of the esophagus is clinically effective and well tolerated.