Enzyme immunoassay of bradykinin using beta-D-galactosidase as a labeling enzyme

Role of the renal kallikrein-kinin system in the development of salt-sensitive hypertension

The role of the renal kallikrein-kinin system in the development of salt-sensitive hypertension was studied using mutant kininogen-deficient Brown-Norway Katholiek (BN-Ka) rats, which generate no kinin in their urine, and other hypertensive rat models. It was found that ingestion of a low sodium diet or infusion of NaCl in doses slightly above 0.15 M caused hypertension and sodium accumulation in erythrocytes and the cerebrospinal fluid of kininogen-deficient BN-Ka rats. Development of hypertension in the deoxycorticosterone-acetate-salt model was completely prevented by administration of a newly discovered inhibitor, ebelactone B, of carboxypeptidase Y-like exopeptidase (an urinary kininase). The urinary kallikrein excretion of spontaneously hypertensive rats was lower than that of Wistar Kyoto rats at 4 weeks of age and did not increase by administration of furosemide, a diuretic agent, although approximately 50% of the diuretic action of this agent was dependent upon the renal kallikrein-kinin system in normal rats. In conclusion, the renal kallikrein-kinin system works as a safety valve for excess sodium intake.

The kallikrein-kininogen-kinin system: lessons from the quantification of endogenous kinins

The purpose of the present review is to describe the place of endogenous kinins, mainly bradykinin (BK) and des-Arg(9)-BK in the kallikrein-kininogen-kinin system, to review and compare the different analytical methods reported for the assessment of endogenous kinins, to explain the difficulties and the pitfalls for their quantifications in biologic samples and finally to see how the results obtained by these methods could complement and extend the pharmacological evidence of their pathophysiological role.

Whale high-molecular-weight and low-molecular-weight kininogens

The expression of high-molecular-weight and low-molecular-weight kininogen mRNAs in the whale liver was examined by reverse transcription-polymerase chain reaction. The nucleotide sequences of the high-molecular-weight and low-molecular-weight kininogen cDNAs were analyzed and deduced to the amino acid sequences. The high-molecular-weight kininogen composed of 609 amino acid residues with 18 signal peptides possessed the consensus sequences of the cysteine protease inhibitor domains I and II, the bradykinin domain, the histidine-rich region, and the prekallikrein-binding region. Except for the histidine-rich region, the overall homologies with bovine, human, and rat high-molecular-weight kininogens were 81%, 76%, and 62%, respectively. The low-molecular-weight kininogen is composed of 408 amino acid residues. The nucleotide sequence down to C(1200) as well as the amino acid sequence till Ile(382) is identical to that of the high-molecular-weight kininogen. The remaining low-molecular-weight kininogen-specific carboxy-terminal portion possessed an amino acid sequence similar to that of the land mammals. The overall homologies with bovine, human, and rat low-molecular-weight kininogens were 82%, 79%, and 64%, respectively. The amino acid sequences of both whale high-molecular-weight and low-molecular-weight kininogens are most similar to those of the bovine among the land mammals analyzed so far. An incubation of dolphin/whale plasma with human plasma kallikrein, or with bovine trypsin, in the presence of carboxypeptidase inhibitors generated bradykinin antigen as well as the spasmogenic activity to the estrous rat uterus. The amount of bradykinin released by the latter enzyme was almost double of the former, indicating that the dolphin/whale plasma contained similar concentrations of low-molecular-weight and high-molecular-weight kininogens.

Lack of Clinically Significant Contact System Activation During Platelet Concentrate Filtration by Leukocyte Removal Filters

When blood (plasma) contacts certain foreign surfaces, factor XII can activate and trigger a series of reactions leading to cleavage of kininogens with subsequent release of bradykinin. In this study, we investigated two different widely used leukocyte removal filters, Pall PXL8K (A) and Asahi PLS-5A (B), to test whether clinically significant contact activation occurred during leukodepletion of platelet-rich plasma (PRP). Kininogens were measured by particle concentration fluorescence immunoassay (PCFIA), which can detect cleavage of high and low molecular weight kininogens (HK and LK), the parent molecules of bradykinin, to determine if contact activation had occurred. A slight, nonsignificant decrease in HK and LK was observed with filter A after the first 5 mL was filtered that returned to prefiltration levels by the end of the filtration. Specific TotK (the combined measurement of HK and LK heavy chains divided by plasma protein concentration) showed a small, significant decrease with filter A after the first 5 mL of platelet concentrates was filtered that returned to prefiltration levels by the end of the filtration. There were no significant increases or decreases in the cleaved kininogen index (CKI), an index of HK proteolytic activation or HK and LK destruction (with release of bradykinin). These data suggest that small amounts of both HK and LK initially adsorb to filter A and then desorb, primarily intact. These data also indicate that no significant contact activation, as measured by PCFIA, occurs during leukodepletion of platelet concentrates with either filter A or B.

Lack of Clinically Significant Contact System Activation During Platelet Concentrate Filtration by Leukocyte Removal Filters

When blood (plasma) contacts certain foreign surfaces, factor XII can activate and trigger a series of reactions leading to cleavage of kininogens with subsequent release of bradykinin. In this study, we investigated two different widely used leukocyte removal filters, Pall PXL8K (A) and Asahi PLS-5A (B), to test whether clinically significant contact activation occurred during leukodepletion of platelet-rich plasma (PRP). Kininogens were measured by particle concentration fluorescence immunoassay (PCFIA), which can detect cleavage of high and low molecular weight kininogens (HK and LK), the parent molecules of bradykinin, to determine if contact activation had occurred. A slight, nonsignificant decrease in HK and LK was observed with filter A after the first 5 mL was filtered that returned to prefiltration levels by the end of the filtration. Specific TotK (the combined measurement of HK and LK heavy chains divided by plasma protein concentration) showed a small, significant decrease with filter A after the first 5 mL of platelet concentrates was filtered that returned to prefiltration levels by the end of the filtration. There were no significant increases or decreases in the cleaved kininogen index (CKI), an index of HK proteolytic activation or HK and LK destruction (with release of bradykinin). These data suggest that small amounts of both HK and LK initially adsorb to filter A and then desorb, primarily intact. These data also indicate that no significant contact activation, as measured by PCFIA, occurs during leukodepletion of platelet concentrates with either filter A or B.

Degradation of T-kininogen by cathepsin D and matrix metalloproteinases

Cathepsin D, matrix metalloproteinase (MMP)-2, MMP-3 (stromelysin), and MMP-9 were isolated from rat granulomatous tissues. HT1080 human fibrosarcoma cells and rheumatoid synovial cell CM. At acidic conditions, cathepsin D cleaved T-kininogen into small peptides and released Met-T-kinin-Leu (kinin precursor), but failed to release kinin. MMP-3 cleaved T-kininogen into a 57 kDa fragment as measured by SDS-PAGE and Western blot analysis using anti-T-kininogen antiserum. On the other hand, no degradation of T-kininogen occurred during incubation with MMP-2 or MMP-9100/1) at pH 7.5 for 7 h.

Effect of etodolac on prostaglandin E2 biosynthesis, active oxygen generation and bradykinin formation

The inhibitory actions of etodolac on prostaglandin (PG) E2 biosynthesis, active oxygen generation and bradykinin formation were compared with those of indomethacin, diclofenac Na, piroxicam, naproxen, ketoprofen and aspirin. The inhibitory action (IC50 5.35 x 10(-8) M) of etodolac on PGE2 biosynthesis in rabbit articular chondrocytes stimulated by interleukin-1 (IL-1) beta was about 1/5 that of indomethacin. The inhibitory action of etodolac on spontaneous PGE2 biosynthesis in rabbit gastric epithelial cells (RGEs) (IC50 2.27 x 10(-5) M) and Madin-Darby canine kidney cells (MDCKs) (IC50 4.54 x 10(-7) M) was much less than that in rabbit articular chondrocytes stimulated by IL-1 beta and about 1/19 and 1/9 that of indomethacin in rabbit gastric epithelial cells (RGEs) and Madin-Darby canine kidney cells (MDCKs), respectively. The inhibitory action of etodolac on active oxygen generation was similar to that of indomethacin and piroxicam, and more potent than that of naproxen, ketoprofen and aspirin. The inhibitory action of etodolac on bradykinin formation was the most potent among the seven anti-inflammatory drugs tested. Both etodolac and bromelain inhibited the inflammatory pain in concanavalin A-treated paws of rats in a dose-dependent manner, but indomethacin did not. These results indicate that etodolac is an anti-inflammatory drug which suppress IL-1 beta-stimulated PGE2 biosynthesis in rabbit articular chondrocytes, active oxygen generation and bradykinin formation. It has less suppressive action against spontaneous PGE2 biosynthesis in RGEs and MDCKs. Thus, etodolac is considered to be a safe anti-inflammatory drug for clinical use.

Human eccrine sweat contains tissue kallikrein and kininase II

We attempted to determine the level of sweat kallikrein (kininogenase) and to purify and characterize it using sweat collected over a white petrolatum barrier. Thermally induced eccrine sweat obtained from 24 healthy subjects showed kallikrein activity of 24.4 ng kinins generated/1 mg of sweat protein when heated plasma was used as the substrate and 16.1 ng kinin when purified low molecular weight bovine kininogen was used as the substrate. Sweat was sequentially purified by Sephacryl S-200, diethyaminoethyl Sephacel, and fast flow liquid chromatography Mono Q chromatography. Sweat kallikrein had a M(r) of 40,000 and was inhibited by aprotinin but not by soybean trypsin inhibitor. The peptide generated by sweat kallikrein was identified as lys-bradykinin using reverse phase high-performance liquid chromatography and by its amino acid sequence. Anti-human urinary kallikrein immunoglobulin G neutralized the sweat kallikrein activity completely, indicating that the sweat kallikrein is the glandular type. Purified sweat and salivary kallikrein showed similar M(r) and responses to inhibitors and antibodies. Using immunohistochemistry, kallikrein activity was localized in luminal ductal cells and in the peripheral rim of secretory coil segments, presumably the outer membrane of the myoepithelium. We also observed kininase activity in sweat at M(r) 160,000, which was inhibited by ethylenediamine tetraacetic acid, captopril, and angiotensin converting enzyme inhibitor peptide, indicating that it is kininase II (or angiotensin converting enzyme). Sweat also contains abundant non-kallikrein hydrolases for S-2266 and S-2302. The demonstration of glandular kallikrein, its tissue localization, and the presence of kininase II in sweat provide the basis for future studies on the physiologic role of the kallikrein/kinin system in the eccrine sweat gland.

Effects of a highly selective plasma kallikrein inhibitor on collagen-induced arthritis in mice

A study was conducted to evaluate the effects of a new, highly selective plasma kallikrein inhibitor, PKSI-527, on collagen-induced arthritis (CIA) in mice. PKSI-527 or indomethacin was administered daily intraperitoneally from day 20 postimmunization. Clinical evaluation was performed, and two of the components of the kallikrein-kinin system, high-molecular-weight (HMW) kininogen and plasma prekallikrein, were assayed. PKSI-527, as well as indomethacin, reduced the severity of arthritis significantly. PKSI-527, but not indomethacin, restored consumed components of the kallikrein-kinin system. These results suggest that PKSI-527 suppresses CIA by modifying the kallikrein-kinin system and PKSI-527 as a synthetic plasma kallikrein inhibitor would be a valuable tool to study the mechanism of inflammation of arthritic diseases.

Detection of the degradation products of bradykinin by enzyme immunoassays as markers for the release of kinin in vivo

We developed an enzyme immunoassay (EIA) specific for Arg1-Pro2-Pro3-Gly4-Phe5 ([1-5]-BK) for determination of the levels of this peptide in biological fluids. Previously developed EIAs for bradykinin (BK) and for des-Phe8-Arg9-BK ([1-7]BK) were also used. Incubation of rat plasma with glass powder resulted in the transient appearance of BK. A degradation product, [1-7]BK, could be detected in the incubation mixture for a longer period of time. When compared with BK and [1-7]BK, a larger amount of [1-5]BK was detectable even longer. In carrageenan-induced pleurisy in rats, which was associated with a peak rate of plasma exudation 5 hr after administration of carrageenan, BK was undetectable (< 160 pg/rat) in the pleural exudates. By contrast, [1-7]BK was detectable over the entire course of the inflammatory response. A larger amount of [1-5]BK was detectable. The peak level of [1-5]BK was 6050 +/- 1050 pg/rat, 5 hr after administration of carrageenan. Inhibition of the generation of BK by intrapleural administration of soy bean trypsin inhibitor (0.3 mg/rat) 30 min before collection of pleural fluid resulted in significant reductions in the levels of both [1-7]BK (by 51-65%) and [1-5]BK (by 63-79%) in the exudates 3, 7 and 19 hr after administration of carrageenan. Intraperitoneal administration of captopril (10 mg/kg) caused a marked reduction (by 98%) in levels of [1-5]BK in exudates 3 hr after administration of carrageenan. The reduction was accompanied by an increase in the level of BK up to 1250% of that in untreated rats. These results indicate that the newly developed EIA for [1-5]BK might be a useful tool for verifying the release of kinin in vivo.

Generation of plasma kinin by three types of protease isolated from Porphyromonas gingivalis 381

Three types of protease (A, B and C) isolated from the culture supernatant of Porphyromonas gingivalis 381 had peculiar activities on kinin generation from high molecular-weight kininogen in vitro. Protease C released bradykinin from the kininogen in a reaction mixture containing 2 mM dithiothreitol, but A and B did not. However, the activity of degrading bradykinin was much stronger in protease A and B than in C. These findings suggest that only protease C shows plasma kallikrein activity.

A useful and sensitive method for demonstration of the involvement of either kallikrein-kinin system in pathological states

In rat carrageenin-induced pleurisy, bradykinin (BK) was hardly able to be detected (< 160 pg per rat) in the exudates. In contrast, des-Phe8-Arg9-BK (des-8,9-BK) level, determined by an enzyme immunoassay (EIA) newly developed, was larger in the exudate and the levels were kept throughout the entire course of this inflammation. Arg-Pro-Pro-Gly-Phe ([1-5] BK) level, measured by an EIA newly developed, was much higher than that of des-8,9-BK in the exudate. Intrapleural administration of soy bean trypsin inhibitor (0.3 mg per rat) reduced the levels of both des-8,9-BK and [1-5] BK in the exudates. Reduction in the residual levels of plasma prekallikrein (P-Kall) and high-molecular-weight-kininogen (HMW-K), not low-molecular-weight-kininogen (LMW-K), were accompanied with increase in these BK degradation products, indicating that plasma prekallikrein was activated in the pleural cavity. On the other hand, intravenous injection of acetaldehyde to rats pretreated with disulfiram resulted in the significant increase in the levels of [1-5] BK in the blood, which was accompanied with reduction in the residual levels of LMW-K, not of HMW-K and P-Kall in plasma. These results indicated that the detection of BK degradation products was a good marker for the kinin release in vivo and that the concomitant reduction of the precursor proteins allowed us to identify the type of kallikrein-kinin systems relevant to the kinin release.

Kinin-generating cascade in advanced cancer patients and in vitro study

The role of the bradykinin-generating system in the pathogenesis of cancer was explored by simultaneously measuring plasma prekallikrein (PK), the precursor of kallikrein, which is the major enzyme responsible for kinin generation, and plasma kininogens (KNG), which are precursors of kinin, in patients with various cancers. The mean value of plasma PK in healthy volunteers was 2.5 +/- 0.5 (mean +/- SD) units/mg plasma protein and that in cancer patients (all stage IV) was 1.7 +/- 0.7 units/mg plasma protein. The mean value of plasma KNG in healthy volunteers was 12.5 +/- 2.0 ng kinin equivalents/mg plasma protein and that in cancer patients was 10.9 +/- 2.8 ng. These data showed that plasma PK and plasma KNG values were significantly lower in cancer patients compared with healthy volunteers (P less than or equal to 0.005 for PK; 0.0005 less than P less than or equal to 0.005 for KNG; n = 28 for healthy subjects; n = 29 for cancer patients). These data appear to indicate that conversion of PK to kallikrein would probably occur with concomitant consumption of KNG by newly generated kallikrein for kinin generation in cancer patients. Early stage cancer patients showed little difference from healthy volunteers. For the in vitro study, activation of purified Hageman factor (HF) and PK was examined by using cancer cell lines and virus-transformed cells that produced plasminogen activator (PA) at a high rate. Both HF and PK were activated in the presence of plasminogen. Diploid cell lines and primary fibroblasts, which did not produce PA, activated neither HF nor PK. Taking all these data together, we conclude that kinin generation does occur in the plasma of patients with advanced cancer, and that one of the initiation mechanisms of the kinin-generating cascade appears to be mediated by plasmin and to depend on cancer cell-derived PA activity.

Immunologic methods for quantitative estimation of small peptides and their application to bradykinin

A simple strategy was developed for the immunologic quantitative determination of small, biologically active peptides utilizing bradykinin (BK) as the model peptide prototype. Methods were developed for the preparation of a peptide-carrier complex suitable for immunization and for immobilization of peptides onto the plastic surface of enzyme-linked immunosorbent assay (ELISA) plates. An avidin-bound biotinylated peptide complex was used for raising peptide antibodies with high titers (1:4000) in the rabbit. The peptide BK was coupled to synthetic polymeric carriers poly-D-lysine (PL) and poly-D-lysine-succinylated (PLS) via the BK carboxy and amino terminus, respectively, with the aid of a water soluble carbodiimide. These carriers with antigen peptide side chains as well as avidin-biotinyl-peptide complexes were efficient surface immobilizing reagents for microwell plastic plates used in the detection of kinins by ELISA. Monoclonal antibodies reacted competitively with kinins in plates coated with either PL-BK or PLS-BK. In contrast, rabbit (polyclonal) antibodies reacted specifically in the plates coated with PLS-BK but only a non-specific reaction could be obtained with the PL-BK coated plates (i.e., could not be displaced with BK). Based on results using synthetic BK analogues, the carboxy terminal half of the BK molecule appears to be the stronger antigenic determinant in both mouse and rabbit systems. The polyclonal antibodies demonstrated a greater affinity to bradykinin compared to the monoclonal antibodies. Their use improved the sensitivity of the ELISA for kinin determination by one order of magnitude. Kinin levels determined in plasma tryptic digests by ELISA with the polyclonal antibodies and PLS-BK system were in agreement with published values.

Enzyme immunoassay for methionine-enkephalin sulfoxide

1. An immunoassay technique employing an enzyme-labelled ligand was developed for the sulfoxide derivative of the opioid peptide methionine-enkephalin (MOE). 2. The sensitivity of the enzyme immunoassay (EIA) was approximately twofold higher than that achieved in the radio-immunoassay (RIA) using tritiated ligand. Cross-reactivities of leucine-enkephalin and beta-endorphin with the EIA were less than 0.1%, while that with Gly-Gly-Phe-Met and oxidized Gly-Gly-Phe-Met were 2.5% and 10.2%, respectively. 3. These results indicate that the EIA is a useful alternative to the RIA for the assay of small peptides.

Demonstration of kinin-release in the peritoneal exudate of kaolin-induced writhing in mice

Using a bradykinin enzyme immunoassay, we measured the amount of kinin in the peritoneal washings of mice with the kaolin-induced writhing reaction. Simultaneous treatment with captopril, a kininase II inhibitor, significantly increased the kinin level at 1 min after kaolin injection. Soybean trypsin inhibitor injected simultaneously with kaolin almost completely suppressed the kinin level at 1 min with or without treatment of captopril. These results suggest that kinin is released through activation of the plasma kallikrein-kinin system by kaolin, and that kinin could be a main mediator for the writhing reaction.

Evidence for the involvement of a plasma kallikrein-kinin system in the immediate hypotension produced by endotoxin in anaesthetized rats

1. In vitro incubation of normal rat plasma with endotoxin from E. coli (3-10 mg ml-1) in the incubation mixture) caused a dose-dependent increase in levels of free kinin and plasma kallikrein in the presence of o-phenanthroline, together with a mirror-image, dose-dependent decrease in the residual levels of the precursors, plasma prekallikrein and high-molecular-weight kininogen. Low-molecular-weight kininogen levels were not modified. 2. Intravenous injection of endotoxin (3-30 mg kg-1) into the femoral vein of anaesthetized rats resulted in dose-dependent hypotension. In blood collected up to 15 min after injection, the levels of prekallikrein and high-molecular-weight kininogen in plasma were decreased while levels of the active forms, plasma kallikrein and free kinin, showed a transient increase in the blood 1 min after administration of endotoxin. 3. A degradation product of bradykinin, des-Phe8-Arg9-bradykinin, as measured by a newly developed enzyme immunoassay, was detectable up to 5 min after administration of endotoxin. 4. Intravenous infusion of soybean trypsin inhibitor inhibited both the formation of bradykinin and des-Phe8-Arg9-bradykinin and the initial hypotension. 5. It can be concluded from our results that plasma prekallikrein is activated in the blood immediately after administration of endotoxin to rats and that bradykinin is a major cause of the immediate hypotension.

Quantitative determination of kinins released by trypsin using enzyme-linked immunosorbent assay (ELISA) and identification by high-performance liquid chromatography (HPLC)

Rapid ELISA and HPLC procedures were developed for quantitation and identification of various natural kinins. Antibradykinin mouse monoclonal antibodies were used to determine kinin levels in the range of 20-200 ng. Bradykinin coupled to bovine serum albumin was used to coat the plates in a 3- to 4-hr ELISA. Synthetic kinin standards isoleucine-seryl-bradykinin (Ileu-Ser-BK), methionyl-lysyl-bradykinin (Met-Lys-BK), tyrosine-bradykinin (Tyr-BK) and bradykinin (BK) yielded almost identical curves with a mixture of A5 and D9 monoclonal antibodies. [Tyr5]-BK, [Tyr8]-BK and des-arginine9 bradykinin (des-Arg9-BK) showed negligible amounts of cross-reactivity. ELISA-compatible trypsin digestion developed for release of kinins from plasma of normal humans, rats and turpentine-treated rats gave values of 3.2, 6.9 and 70 micrograms/ml plasma, respectively. High performance liquid chromatography methods were developed for complete resolution of kinins on a C-18 reversed phase mu-Bondapak column before and after derivatization with phenyl isothiocyanate (PITC). The simple PITC derivatization procedure yielded good quantitation above 20 pmol. The ELISA and HPLC methods were used in a complementary fashion to assay and identify kinins in biological fluids as well as during the course of kininogen purification.

The Hageman factor-dependent system in the vascular permeability reaction

The mechanism by which the Hageman factor-dependent system induces vascular permeability has been analyzed. The Mr-28,000 active fragment of guinea pig Hageman factor (beta-HFa), injected intradermally, induces an increase in local vascular permeability. Inhibition of vascular permeability resulted from pretreatment of the beta-HFa with immunopurified anti-Hageman factor F(ab')2 antibody at concentrations of 10(-6)-10(-7) M as well as by incubation with corn and pumpkin seed inhibitors of beta-HFa. To determine whether prekallikrein and kallikrein participated in the permeability induced by beta-HFa, circulating prekallikrein was depleted by intra-arterial injections of anti-prekallikrein F(ab')2 antibody. This resulted in about 80% diminution of the vascular permeability response to beta-HFa, without affecting the permeability reaction to bradykinin. Soybean trypsin inhibitor (10(-6) M), injected at the same cutaneous site as the beta-HFa, inhibited the vascular permeability response to beta-HFa by more than 90%. This concentration of soybean inhibitor blocked more than 90% of the activity of guinea pig plasma kallikrein, but did not inhibit the amidolytic capacity of beta-HFa. The permeability activity of beta-HFa (but not its amidolytic activity) was augmented 10-fold by simultaneous injection of a synthetic kinin potentiator, SQ 20,881 (Glu-Tyr-Pro-Arg-Pro-Gln-Ile-Pro-Pro-OH), and was almost completely inhibited by the simultaneous injection of a kinin-destroying enzyme, carboxypeptidase B. These results support the hypothesis that the greatest proportion of vascular permeability induced by beta-HFa is produced by the activation of prekallikrein followed by the release of kinin in the cutaneous tissue. These data offer the first in vivo evidence that the Hageman factor-dependent system by itself can induce inflammatory changes.

Enzyme immunoassay of buprenorphine

Assays for the potent, highly lipophilic analgesic buprenorphine described in the literature include the radioimmunoassay (RIA), radioreceptor assay (RRA) and selected ion-monitoring. Problems arise with the use of hazardous and unstable ligand in the RIA and RRA and the need for an extraction step for RRA and selected ion-monitoring. An enzyme immunoassay (EIA) was developed to allow rapid and simple analysis of plasma concentrations of drug without these disadvantages. The N-dealkylated derivative of buprenorphine, norbuprenorphine, was labelled with beta-D-galactosidase using the linking agent N-(gamma-maleimidobutyryloxy) succinimide. This enzyme-labelled hapten was used to develop an EIA for buprenorphine. The assay is sensitive enough to measure 10 pg of buprenorphine. Endogenous opioid peptides do not cross-react in the assay; norbuprenorphine itself was completely cross-reactive. Since the presence of plasma (100 microliters) has no effect on the standard curve, plasma levels in humans were determined by this EIA without extraction after intravenous or sublingual administration of the drug. The EIA therefore represents a good alternative to existing assays for buprenorphine-like material with the advantages of simplicity, safety, sensitivity and ease of handling.

Effect of bromelain on kaolin-induced inflammation in rats

The effects of stem bromelain on the plasma kallikrein system, bradykinin levels and plasma exudation at the inflammatory site were examined in rats with a kaolin-induced inflammation of an air pouch. Bromelain (5, 7.5 mg/kg) caused a dose-dependent decrease of bradykinin levels at the inflammatory site and a parallel decrease of the prekallikrein levels in sera. Plasma exudation was also reduced dose dependently. Bradykinin-degrading activity in sera was elevated after treatment with bromelain, although it was unchanged in the pouch fluid. These data indicate that bromelain inhibits plasma exudation through inhibiting the generation of bradykinin at the inflammatory site via depletion of the plasma kallikrein system.

Partial purification of plasma and tissue kallikreins in psoriatic epidermis

Human psoriatic scale extracts produced kinins from heated plasma (11.3 +/- 5.5 ng kinin/mg protein) and from purified low molecular weight (LMW) bovine kininogen (4.4 +/- 1.7 ng/mg). Sephacryl S-200 gel filtration of the extracts showed three peaks of kininogenase activity with Mr values of 90,000 (K-I), 65,000 (K-II), and 35,000 (K-III). Upon DEAE-Sepharose chromatography of the Sephacryl peaks, K-I activity was found in the nonadsorbed fraction and formed kinins only from heated plasma. Peak K-II activity was resolved into two peaks, K-IIa (in the nonadsorbed fraction), which formed kinins only from heated plasma, and K-IIb (in the adsorbed fraction), which formed kinins from both heated plasma and LMW bovine kininogen. K-III kininogenase activity appeared at the same position as K-IIb and also formed kinins from both substrates. Kininogenases K-I and K-IIa had the same Km value (0.3 mM) with Pro-Phe-Arg-p-nitroanilide(pNA), similar to that found with human plasma kallikrein. The Km value of K-IIb with Val-Leu-Arg-pNA (0.8 mM) was like that found for human salivary kallikrein, whereas K-III had a low affinity for this substrate. Like plasma kallikrein, K-I and K-IIa were inhibited by soybean trypsin inhibitor, but only weakly by aprotinin. In addition the kininogenase activity of both K-I and K-IIa was neutralized by adding antihuman prekallikrein immunoglobulin G (IgG). In contrast, K-IIb and K-III were strongly inhibited by aprotinin but not by soybean trypsin inhibitor, consistent with their being tissue kallikreins. It was confirmed that K-IIb and K-III shares antigenic determinant of urinary kallikrein.

Role of bradykinin in the vascular permeability response induced by carrageenin in rats

1 Bradykinin in carrageenin-induced inflammatory pouch fluid was measured by an enzyme immunoassay method. 2 The bradykinin showed a single peak in the 30-60 min period after the challenge and then decreased quickly, and there was a correlation between the bradykinin level and exudation of fluorescein-labelled bovine serum albumin in the first 60 min period. 3 Captopril (an inhibitor of kininase II) elevated both the bradykinin level in the inflammatory pouch fluid and vascular permeability, while DL-2-mercaptomethyl-3- guanidinoethylthiopropanoic acid (an inhibitor of kininase I) had no effect. 4 Soybean trypsin inhibitor (SBTI) inhibited the vascular permeability response in parallel with the decrease in the bradykinin level. 5 A bradykinin-degrading activity appeared in the pouch fluid within 1 h after the challenge and increased with time. 6 In the period of 3.5-4 h, bradykinin levels were suppressed below the sensitivity limit of the assay, i.e. 0.07 nm ml-1, in spite of active generation. This was because degradation of bradykinin was very rapid in this late stage. Nevertheless, bradykinin still played a definite role in sustaining a high level of vascular permeability response in the late stage in conjunction with prostaglandins.

Identification of T-kinin-Leu(T-kinin-containing peptide) released from T-kininogen by cathepsin D of granulomatous tissues in rats

Acid proteinases of granulomatous tissues in rats with carrageenin-induced inflammation released kinin from T-kininogen. By column chromatography on pepstatin-Sepharose 4B, two types of acid proteinase seems to be responsible for kinin release. One of the acid proteinase was identified as cathepsin D from SDS-polyacrylamide gel electrophoresis and Western-blot analysis, using anti-rat liver cathepsin D IgG. Cathepsin D alone could not release T-kinin, but T-kinin-containing peptides. The T-kinin-containing peptides were separated into two peptides by reverse-phase high-performance liquid chromatography. From determination of its amino acid composition and its immunoreactivity toward anti-bradykinin antiserum, one of the T-kinin-containing peptides was identified as T-kinin-Leu.

Characterization of guinea-pig high-molecular-weight kininogen as multi-functional molecule

High-molecular-weight (HMW) kininogen was purified from guinea-pig plasma by measuring its ability to correct the prolonged clotting time in human HMW kininogen deficient plasma (Fitzgerald trait). The purified HMW kininogen demonstrated a homogeneous band in disc gel electrophoresis in the presence of sodium dodecyl sulfate under reducing or non-reducing conditions with an apparent molecular weight of 100,000. Kinin released from HMW kininogen by treatment with guinea-pig plasma kallikrein was identified as bradykinin by reverse-phase HPLC and amino-acid analysis. The capacity of HMW kininogen as a thiol-proteinase inhibitor was realized by its dose-dependent inhibitory activity to papain. The Ki value for papain was estimated to be 42 pM. The kinin-free HMW kininogen maintained the inhibitor and clotting-factor activities with similar capacities to those of the HMW kininogen molecule. Heavy chain (H-chain) and light chain (L-chain) of HMW kininogen were prepared from reduced and alkylated kinin-free HMW kininogen by HPLC. The S-alkylated H-chain, but not L-chain, demonstrated the inhibitor activity with the Ki value 6.9 nM for papain, whereas the S-alkylated L-chain, but not H-chain, maintained the clotting activity one-third of the capacity of HMW kininogen. Specific antibodies recognized HMW kininogen, but also a probable low-molecular-weight kininogen(s) with an apparent molecular weight of 60,000 in the guinea-pig plasma. All of these properties are consistent with the reports on human, bovine and rat HMW kininogen.

Ile-Ser-bradykinin (T-kinin) and Met-Ile-Ser-bradykinin (Met-T-kinin) are released from T-kininogen by an acid proteinase of granulomatous tissues in rats

An acid proteinase of granulomatous tissues in rats with carrageenin-induced inflammation released kinin from T-kininogen. The kinin isolated by n-butanol extraction was separated by reverse-phase high-performance liquid chromatography into T-kinin and a T-kinin derivative. From determination of its amino acid composition and its immunoreactivity toward anti-bradykinin antiserum, the T-kinin derivative was identified as Met-Ile-Ser-bradykinin (Met-T-kinin).