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Y T Wachtfogel

Publications and source records attributed to Y T Wachtfogel.

At least 19 recordsLinked to original sources
PubMed1998

Thrombin and human plasma kallikrein inhibition during simulated extracorporeal circulation block platelet and neutrophil activation.

Cardiopulmonary bypass causes hemorrhagic complications, and initiates a chemical and cellular inflammatory response. Contact of blood with synthetic surfaces leads to qualitative and quantitative alterations in platelets, neutrophils, complement, and contact systems. Despite the fact that cardiopulmonary bypass is carried out in the presence of high doses of heparin, there is significant activation of both platelets and neutrophils. Thrombin is protected on cell and fibrin surfaces from antithrombin, even in the presence of high doses of heparin (approximately 5 U/ml). We therefore studied the effect of a small (Mr = 497), highly effective (Ki = 41 pM), reversible tripeptide inhibitor of thrombin, DUP 714 (1 microM), in a well characterized model of simulated extracorporeal circulation. In the absence of DUP 714, platelet counts decreased by 75% 5 min after the start of extracorporeal bypass and increased to 48% at 120 min of recirculation. DUP 714 significantly preserved platelet counts, decreased plasma levels of platelet beta-thromboglobulin levels, but did not prevent a decrease in sensitivity of platelets to adenosine diphosphate. Kallikrein-C1-inhibitor and C1-C1-inhibitor complexes increased progressively from 0.32 U/ml to 0.67 U/ml and from 4.45 U/ml to 7.25 U/ml, respectively, during 120 min of recirculation without DUP 714. Addition of DUP 714 significantly inhibited kallikrein-C1-inhibitor complex formation but did not affect C1-C1-inhibitor complexes. In the absence of DUP 714, human neutrophil elastase levels rose from a baseline of 0.01 +/- 0.00 microg/ml to 1.18 +/- 0.21 microg/ml during 120 min of recirculation. Human neutrophil elastase release at 120 min was significantly inhibited in the presence of DUP 714 to 37% of the value with heparin alone. These results indicated that addition of this novel thrombin (and kallikrein) inhibitor to heparin preserved platelet counts, decreased platelet secretion, and provided the additional benefit of partially blocking neutrophil activation during simulated extracorporeal circulation.

Cardiopulmonary Bypass↗
PubMed1995

Selective kallikrein inhibitors alter human neutrophil elastase release during extracorporeal circulation.

Cardiopulmonary bypass causes hemorrhagic complications and initiates a biochemical and cellular "whole body inflammatory response." This study investigates whether a variety of selective inhibitors of the contact pathway of intrinsic coagulation modulate complement and neutrophil activation during simulated extracorporeal circulation. After 60 min of recirculation in the presence of the slow tight-binding boronic acid inhibitor, Bz-Pro-Phe-boroArg-OH (10.7 microM), complete inhibition of kallikrein-C1-inhibitor complex formation and marked inhibition of C1-C1-inhibitor complex formation and the release of human neutrophil elastase were observed. Arg15-aprotinin (3.1 microM), Ala357,Arg358 alpha 1-antitrypsin (2.6 microM), and soybean trypsin inhibitor (48.0 microM) either completely or partially inhibited the generation of kallikrein-C1-inhibitor complexes but were less effective inhibitors of human neutrophil elastase release. The second-order rate constants for the inhibition of kallikrein in purified systems are consistent with the order of effectiveness of the inhibitors in blocking human neutrophil elastase release in heparinized blood. Our results suggest that low-molecular-weight selective inhibitors of kallikrein may be effective agents in the attenuation of the contact-mediated inflammatory response in cardiopulmonary bypass.

Amino Acid Sequence↗
PubMed1994

High molecular weight kininogen binds to Mac-1 on neutrophils by its heavy chain (domain 3) and its light chain (domain 5).

High molecular weight kininogen (HK) binds specifically, saturably, and reversibly to neutrophils and also reciprocally inhibits the binding of fibrinogen to neutrophils. Since fibrinogen binds to the leukocyte integrin CD11b/18 (Mac-1, alpha M beta 2), we investigated whether HK bound to Mac-1 and whether the binding site was similar to that for factor X. We also examined whether one or both chains of cleaved HK (HKa) were involved. Two monoclonal antibodies, 2B5 (0.29 microM) to HK heavy chain domains 2 (D2) and 3 (D3), and C11C1 (0.26 microM) to HK light chain domain 5 (D5), inhibited by 99 and 93% the binding, respectively, of 125I-HK (8.3 nM) to neutrophils. To minimize steric hindrance, we further demonstrated that the Fab' fragments of 2B5 and C11C1 were able to inhibit the binding of this ligand to virtually the same extent as the intact antibody, indicating that, as in binding of HK to platelets and endothelial cells, both chains are involved. To directly demonstrate the involvement of each chain, we showed that the reduced alkylated light chain derived from HK and low molecular weight kininogen, which contains the same heavy chain as HK, each markedly inhibited the binding of HK to neutrophils. We localized the domain responsible for the binding in each chain by showing that recombinant D3 and D5 decreased the binding of HK to neutrophils. To define the receptor for HK, we employed three monoclonal antibodies to Mac-1: OKM1 and OKM10 to epitopes on the alpha M subunit and IB4 to an epitope on the beta 2 chain. OKM1, which can inhibit fibrinogen binding to neutrophils, inhibited HK binding by 79%, whereas the other antibodies inhibited HK binding less than 25%. Coagulation factor X also binds to Mac-1 on monocytes at a similar site to C3bi. Synthetic peptides which define noncontiguous surface loops in factor X that interact with Mac-1, failed to inhibit 125I-HK binding to neutrophils. We conclude that HK binds, via domains on its heavy chain, D3, and light chain, D5, to Mac-1 on the neutrophil surface, and HK occupies a site overlapping with fibrinogen and different from factor X.

Amino Acid Sequence↗
PubMed1994

Alpha 1-antitrypsin Pittsburgh (Met358-->Arg) inhibits the contact pathway of intrinsic coagulation and alters the release of human neutrophil elastase during simulated extracorporeal circulation.

Cardiopulmonary bypass prolongs bleeding time, increases postoperative blood loss, and triggers activation of plasma proteolytic enzyme systems and blood cells referred to as the "whole body inflammatory response". Contact of blood with synthetic surfaces leads to qualitative and quantitative alterations in platelets, neutrophils, contact and complement systems. Contact and complement pathway proteins both induce neutrophil activation. alpha 1-antitrypsin Pittsburgh (Met358-->Arg), a mutant of alpha 1-antitrypsin, is a potent inhibitor of plasma kallikrein and thrombin. We investigated whether this recombinant mutant protein inhibited platelet activation, as well as contact and/or complement-induced neutrophil activation during simulated extracorporeal circulation. Arg358 alpha 1-antitrypsin did not prevent the 34% drop in platelet count at 5 min of recirculation, did not block the 50% decrease in ADP-induced platelet aggregation at 120 min of recirculation, nor inhibit the release of 6.06 +/- 1.07 micrograms/ml beta-thromboglobulin at 120 min of recirculation suggesting that the inhibitor had little effect on platelet activation. However, Arg358 alpha 1-antitrypsin totally blocked kallikrein-C1-inhibitor complex formation but not C1-C1-inhibitor complex formation. Most importantly, Arg358 alpha 1-antitrypsin decreased the release of 1.11 +/- 0.16 micrograms/ml human neutrophil elastase by 43%. The attenuation of neutrophil activation in the absence of an effect on complement activation via the classical pathway, supports the concept that kallikrein is a major mediator of neutrophil degranulation during cardiopulmonary bypass.

Arginine↗
PubMed1993

Genetic basis of total kininogen deficiency in Williams' trait.

High and low molecular weight kininogens (HK and LK) modulate inflammatory responses, serve as precursors of kinins, inhibit cysteine proteinases, and modulate thrombin activation of platelets. Differential splicing yields two different mRNAs for HK and LK. We report the first molecular characterization of a kininogen gene mutation in a patient lacking LK and HK. No gross DNA deletion or insertion was detected by Southern blots, and LK and HK mRNAs were normal size on Northern blots. Exon sequences amplified by polymerase chain reaction showed a C-->T transition at nucleotide 587, resulting in a CGA (Arg)--> TGA (Stop) mutation in exon 5 before the splice site in exon 10, thus preventing synthesis of both HK and LK. The mutation eliminated the recognition site of the restriction enzyme Csp45I. Results of Csp45I digestion of the polymerase chain reaction-amplified exon 5 DNA fragment of the patient (lacking kininogens), three daughters (approximately 50% HK), and 1 granddaughter (normal HK) revealed that the patient was homozygous, while the three daughters were heterozygous, and the granddaughter was normal. We conclude that a single base mutation in the kininogen gene exon 5 was responsible for kininogen deficiency in the Williams family.

Base Sequence↗
PubMed1993

Aprotinin inhibits the contact, neutrophil, and platelet activation systems during simulated extracorporeal perfusion.

Aprotinin reduces blood loss after cardiac operations and decreases the bleeding time. The mechanism of action of aprotinin that produces these effects is not clear. During simulated extracorporeal circulation the contact and complement systems, platelets, and neutrophils are activated. We investigated the effect of aprotinin on kallikrein-C1-inhibitor complex and C1-C1-inhibitor complex formation, neutrophil degranulation, and platelet release and aggregation during simulated extracorporeal circulation. Fresh heparinized human blood was recirculated at 37 degrees C for 2 hours in a spiral coil membrane oxygenator-roller pump perfusion circuit. Changes in platelet count, leukocyte count, platelet response to adenosine diphosphate, and plasma levels of beta-thromboglobulin, kallikrein-C1-inhibitor complexes, C1-C1-inhibitor complexes, and neutrophil elastase were measured before and at 5, 30, 60, and 120 minutes of recirculation at 0, 0.015, 0.03, 0.06, and 0.12 mg/ml doses of aprotinin. Platelet counts decreased to 36% +/- 12% of control values at 5 minutes and increased to 56% +/- 13% at 120 minutes without aprotinin. Aprotinin did not affect platelet counts, but it did prevent the decrease in sensitivity of platelets to adenosine diphosphate and it attenuated beta-thromboglobulin release. In the absence of aprotinin, kallikrein-C1-inhibitor and C1-C1-inhibitor complexes increased progressively to 0.53 +/- 0.14 U/ml and 2.38 +/- 0.33 U/ml, respectively, at 120 minutes. Kallikrein-C1-inhibitor complexes were completely inhibited and C1-C1-inhibitor complexes were partially inhibited at aprotinin concentrations of 0.03 mg/ml or greater. Release of neutrophil elastase was partially but not completely inhibited at the highest dose of aprotinin and was 50% inhibited at a dose of 0.03 mg/ml. Because activation of the fibrinolytic system does not occur in this system, the changes were independent of the inhibition of plasmin. We conclude that aprotinin in high doses completely inhibited kallikrein-induced activation of neutrophils and partially inhibited complement-induced activation. Aprotinin did not directly affect platelet adhesion or aggregation, but it indirectly preserved platelet sensitivity to agonists and also attenuated release of alpha-granule contents. The data indicate that in the presence of aprotinin platelet function was partially preserved, kallikrein production was totally inhibited, complement activation was partially inhibited, and neutrophil release was partially inhibited, thus attenuating the "whole body inflammatory response" associated with cardiopulmonary bypass.

Aprotinin↗
PubMed1992

Rabbit trachealis tension responses to receptor-mediated agonists are diminished by elastase.

The present study examined the effects of elastase, in concentrations present in respiratory secretions, on airway smooth muscle contractile responses in vitro and the magnitude of the airway epithelial inhibition of smooth muscle tension. Experiments were performed on 126 full-thickness tracheal strips from 25 rabbits. Isometric tension responses to acetylcholine (10(-8) to 10(-4) M) and potassium chloride (10 to 110 mM) were examined before and after a 5-min exposure to either porcine pancreatic elastase (PPE) or human neutrophil elastase (HNE). PPE (5 to 40 micrograms/100 microliters) reduced the tension response to acetylcholine but had no effect on the tension response to potassium chloride. PPE and HNE (20 micrograms/100 microliters) produced similar effects. Mechanical removal of the epithelium per se significantly (P less than 0.005) decreased the ED50 response to acetylcholine but did not affect maximal tension. However, the airway epithelial inhibitory effect on the acetylcholine tension response was similar in the presence and absence of PPE (20 micrograms/100 microliters). These data suggest that the diminution of tracheal smooth muscle tension responses to receptor-mediated agonists induced by elastase is a direct effect on the muscle and is not mediated by an effect of elastase on the respiratory epithelium.

Acetylcholine↗
PubMed1992

Plasma elastase alpha 1-antitrypsin and lactoferrin in sepsis: evidence for neutrophils as mediators in fatal sepsis.

Increased vasopermeability and vasodilation, presumably the result of endothelial perturbation, are considered among the basic pathogenetic mechanisms in septic shock. Neutrophils have been implicated as a source for mediators in endothelial injury. We measured elastase-alpha 1-antitrypsin (alpha 1AT) complexes and lactoferrin as markers for release of neutrophil granule contents in plasma from patients with sepsis on admission to the Intensive Care Unit, and we delineated the relationship of neutrophil activation to other inflammatory parameters and to hemodynamic and biochemical parameters. Levels of elastase-alpha 1AT and lactoferrin significantly correlated with each other (r = 0.58; p less than 0.008), and were increased (greater than 3.33 and 5 nmol/L, respectively) in 96% and 71% of the patients, respectively. Lactoferrin, but not elastase-alpha 1AT, correlated with the number of white blood cells (r = 0.38; p = 0.008). Elastase-alpha 1 AT levels were significantly higher (p = 0.008), whereas white blood cell counts were lower (p = 0.015) in patients with shock when compared with patients without abnormal blood pressure. Both elastase-alpha 1AT and lactoferrin levels correlated with lactate levels (r = 0.33; p = 0.024 and r = 0.30; p = 0.04), suggesting a role for neutrophil activation in the pathogenesis of hypoxygenation. In addition, elastase-alpha 1AT correlated with the concentrations of interleukin 6 (IL-6) (r = 0.46; p = 0.001) and C3a (r = 0.38; p = 0.009), suggesting that cytokines and complement may contribute to the degranulation of neutrophils in sepsis. Elastase-alpha 1AT complexes were inversely related to C1-inhibitor (r = -0.33; p = 0.028) and to platelet numbers (r = -0.42; p = 0.003). Levels of elastase-alpha 1AT complexes in plasma appeared to be of prognostic significance; levels were higher in 27 patients who died than in 21 patients who survived (p = 0.01). The mortality in 27 patients with concentrations below 10 nM was 37%, whereas it was 81% in 21 patients with higher levels. The overall mortality in this study was 56%. These results provide further evidence that activation and degranulation of neutrophils, induced by multiple agonists, are involved in the development of fatal complications in patients with sepsis.

Bacterial Infections↗
PubMed1989

High molecular weight kininogen inhibits fibrinogen binding to cytoadhesins of neutrophils and platelets.

Fibrinogen inhibited 125I-high molecular weight kininogen (HMWK) binding and displaced bound 125I-HMWK from neutrophils. Studies were performed to determine whether fibrinogen could bind to human neutrophils and to describe the HMWK-fibrinogen interaction on cellular surfaces. At 4 degrees C, the binding of 125I-fibrinogen to neutrophils reached a plateau by 30 min and did not decrease. At 23 and 37 degrees C, the amount of 125I-fibrinogen bound peaked by 4 min and then decreased over time because of proteolysis of fibrinogen by human neutrophil elastase (HNE). Zn++ (50 microM) was required for binding of 125I-fibrinogen to neutrophils at 4 degrees C and the addition of Ca++ (2 mM) increased the binding twofold. Excess unlabeled fibrinogen or HMWK completely inhibited binding of 125I-fibrinogen. Fibronectin degradation products (FNDP) partially inhibited binding, but prekallikrein and factor XII did not. The binding of 125I-fibrinogen at 4 degrees C was reversible with a 50-fold molar excess of fibrinogen or HMWK. Binding of 125I-fibrinogen, at a concentration range of 5-200 micrograms/ml of added radioligand, was saturable with an apparent Kd of 0.17 microM and 140,000 sites/cell. The binding of 125I-fibrinogen to neutrophils was not inhibited by the peptide RGDS derived from the alpha chain of fibrinogen or by the mAb 10E5 to the platelet glycoprotein IIb/IIIa heterodimer. Fibrinogen binding was inhibited by a gamma-chain peptide CYGHHLGGAKQAGDV and by mAb OKM1 but was not inhibited by OKM10, an mAb to a different domain of the adhesion glycoprotein Mac-1 (complement receptor type 3 [CR3]). HMWK binding to neutrophils was not inhibited by OKM1. These observations were consistent with a further finding that fibrinogen is a noncompetitive inhibitor of 125I-HMWK binding to neutrophils. Fibrinogen binding to ADP-stimulated platelets was increased twofold by Zn++ (50 microM) and was inhibited by HMWK. These studies indicate that fibrinogen specifically binds to the C3R receptor on the neutrophil surface through the carboxy terminal of the gamma-chain and that HMWK interferes with the binding of fibrinogen to integrins on both neutrophils and activated platelets.

Antibodies, Monoclonal↗
PubMed1989

Human neutrophils contain and bind high molecular weight kininogen.

Because plasma kallikrein activates human neutrophils, and in plasma prekallikrein (PK) circulates complexed with high molecular weight kininogen (HMWK), we determined whether HMWK could mediate kallikrein's association with neutrophils. HMWK antigen (237 +/- 61 ng HMWK/10(8) neutrophils) was present in lysates of washed human neutrophils. Little if any plasma HMWK was tightly bound and nonexchangeable with the neutrophil surface. Human neutrophils were found to possess surface membrane-binding sites for HMWK but no internalization was detected at 37 degrees C. 125I-HMWK binding to neutrophils was dependent upon Zn2+. Binding of 125I-HMWK to neutrophils was specific and 90% reversible. 125I-HMWK binding to neutrophils was saturable with an apparent Kd of 9-18 nM and 40,000-70,000 sites per cell. Upon binding to neutrophils, 125I-HMWK was proteolyzed by human neutrophil elastase (HNE) into lower relative molecular mass derivatives. Furthermore, HMWK found in neutrophils also served as a cofactor for HNE secretion because neutrophils deficient in HMWK have reduced HNE secretion when stimulated in plasma deficient in HMWK or with purified kallikrein. These studies indicate that human neutrophils contain a binding site for HMWK that could serve to localize plasma or neutrophil HMWK on their surface to possibly serve as a receptor for kallikrein and to participate in HNE secretion by this enzyme.

Antigens↗
PubMed1989

Formation of C1s-C1-inhibitor, kallikrein-C1-inhibitor, and plasmin-alpha 2-plasmin-inhibitor complexes during cardiopulmonary bypass.

Stimulation of platelets and neutrophils occurs during clinical cardiopulmonary bypass. We investigated whether the classical complement, contact, or fibrinolytic pathways are activated as potential sources of neutrophil agonists. Using enzyme-linked immunosorbent "sandwich" assays specific for C1s-C1-and kallikrein-C1-inhibitor complexes respectively, we found that there was a modest increase in plasma levels of each complex after clinical cardiopulmonary bypass was completed. The increased concentration of enzyme-inhibitor complexes reverted to baseline within 24 hours. Since these complexes are cleared in vivo, we measured their formation by assaying their plasma levels during in vitro simulated extracorporeal circulation. Over a period of two hours, C1s-C1-inhibitor complexes rose from a baseline of 2 +/- 1 nmol/L to 21 +/- 2 nmol/L, and kallikrein-C1-inhibitor complexes rose from 2 +/- 1 nmol/L to 25 +/- 5 nmol/L. However, there was no evidence of either in vivo or in vitro plasmin-alpha 2-plasmin-inhibitor complex formation. These results indicate that the pathways of classical complement and contact activation, but probably not fibrinolysis, may be associated with neutrophil activation seen during clinical cardiopulmonary bypass.

Adult↗
PubMed1988

Fibronectin degradation products containing the cytoadhesive tetrapeptide stimulate human neutrophil degranulation.

We investigated whether adhesive glycoproteins, such as fibronectin or fibrinogen, could function to provide a nidus for neutrophil degranulation. Elastase release in recalcified plasma was normal in afibrinogenemic plasma, but 73% less in plasma depleted of fibronectin. Proteolytic digests of fibronectin, but not intact fibronectin (50-1,000 micrograms/ml), induced a concentration-dependent release of neutrophil elastase and lactoferrin. MAbs N293, which recognized the mid-molecule of fibronectin, N294, which was directed toward the 11-kD cell adhesive fragment, and N295, generated against the amino terminal of the 11-kD fragment, inhibited the release of elastase by 7, 24, and 60%, respectively. The cytoadhesive tetrapeptide portion of fibronectin, Arg-Gly-Asp-Ser (250-1,000 micrograms/ml), released 1.94 +/- 0.10 micrograms/ml of elastase from 10(7) neutrophils, in contrast to the lack of release by the control hexapeptide, Arg-Gly-Tyr-Ser-Leu-Gly. Plasmin appeared to be the enzyme responsible for fibronectin cleavage, since neutrophil elastase release in plasma that had been depleted of plasminogen was decreased and reconstitution of plasminogen-deficient plasma with purified plasminogen corrected the abnormal release. Plasmin cleaved fibronectin to multiple degradation products, each less than 200 kD. This fibronectin digest released 1.05 microgram/ml of elastase from 10(7) neutrophils. We suggest that the activation of plasminogen leads to the formation of fibronectin degradation products capable of functioning as agonists for neutrophils.

Antibodies, Monoclonal↗
PubMed1988

Differential requirements for platelet aggregation and inhibition of adenylate cyclase by epinephrine. Studies of a familial platelet alpha 2-adrenergic receptor defect.

We describe a family whose members have impaired platelet aggregation and secretion responses to epinephrine with normal responses to adenosine diphosphate and collagen. Platelet alpha 2-adrenergic receptors (measured using 3H methyl-yohimbine) were diminished in the propositus (78 sites per platelet), his two sisters (70 and 27 sites per platelet), and parents (37 and 63 sites per platelet), but not in two maternal aunts (12 normal subjects, 214 +/- 18 sites per platelet; mean +/- SE). However, the inhibition of cyclic adenosine monophosphate (cAMP) levels by epinephrine in platelets exposed to 400 nmol/L PGI2 was similar in the patients and five normal subjects (epinephrine concentration for 50% inhibition, 0.04 +/- 0.01 mumol/L v 0.03 +/- 0.01 mumol/L; P greater than .05). In normal platelets, the concentration of yohimbine (0.18 mumol/L) required for half maximal inhibition of aggregation induced by 2 mumol/L epinephrine was lower than that for inhibition of its effect on adenylate cyclase (1.6 mumol/L). In quin2 loaded platelets, thrombin (0.1 U/mL) stimulated rise in cytoplasmic Ca2+ concentration, [Ca2+]i, was normal in the two patients studied. The PGI2 analog ZK 36,374 completely inhibited thrombin-induced rise in [Ca2+]i; the reversal of this inhibition by epinephrine was normal in the two patients. Thus, despite the impaired aggregation response to epinephrine, platelets from these patients have normal ability to inhibit PGI2-stimulated cAMP levels. These patients with an inherited receptor defect provide evidence that fewer platelet alpha 2-adrenergic receptors are required for epinephrine-induced inhibition of adenylate cyclase than for aggregation.

Adenosine Diphosphate↗
PubMed1987

Human neutrophil degranulation during extracorporeal circulation.

Cardiopulmonary bypass, especially when prolonged, may result in hemostatic failure and pulmonary dysfunction, which has been attributed to changes in platelets and leukocytes, respectively. It has been well documented that contact of blood with synthetic surfaces causes platelet activation. In this report, we explore mechanisms of the activation of neutrophils during simulated in vitro extracorporeal circulation and document the release of neutrophil lactoferrin and elastase during clinical cardiopulmonary bypass (CCB). Inhibition in the simulated circuit by prostaglandin E1 (PGE1) and lidocaine suggests different mechanisms for release of neutrophil-specific proteins. During CCB with a bubble oxygenator it was observed that platelet counts fell to 42% +/- 2% of baseline. In addition, beta-thromboglobulin antigen (beta TG), a platelet-specific, alpha-granule protein marker reflecting the release reaction, increased from 0.15 +/- 0.05 to 0.84 +/- 0.11 microgram/mL. Neutrophil counts decreased to 67% +/- 7% of prebypass levels but then gradually rose as bypass continued. Both lactoferrin, a neutrophil-specific granule marker, and neutrophil elastase, an azurophilic granule marker, increased in plasma threefold to 1.66 +/- 0.33 micrograms/mL and 1.65 +/- 0.68 microgram/mL, respectively, just before bypass was stopped. When fresh heparinized human blood was recirculated within an extracorporeal membrane oxygenator bypass circuit for 120 minutes, plasma beta-TG rose to 5.13 micrograms/mL, lactoferrin increased from 0.13 +/- 0.04 to 1.62 +/- 0.22 micrograms/mL, and neutrophil elastase rose from 0.05 +/- 0.02 to 1.86 +/- 0.41 micrograms/mL. At 120 minutes, lidocaine (100 mumol/L), which inhibits neutrophil activation, delayed release of lactoferrin (1.33 +/- 0.26 micrograms/mL) and markedly inhibited release of elastase (0.24 +/- 0.05 microgram/mL) but did not inhibit release of beta-TG antigen (5.66 micrograms/mL at 120 minutes). PGE1 (0.3 mumol/L) inhibited significantly the release of beta-TG (0.31 microgram/mL) and elastase (0.52 +/- 0.11 microgram/mL) and attenuated the release of lactoferrin (1.57 +/- 0.45 micrograms/mL).

Alprostadil↗
PubMed1986

Effects of verapamil and diltiazem on human platelet function.

In this study the antiplatelet properties of two calcium channel blockers, verapamil and diltiazem, were evaluated. In 20 random aspirin-abstaining donors, both diltiazem and verapamil (0.01-10 microM) reduced epinephrine-induced aggregation [46 +/- 6% (SE) inhibition] and demonstrated a dose-dependent inhibition of epinephrine-induced [14C]serotonin release (43 +/- 3% reduction). However, at equimolar concentrations, verapamil was twice as effective. Neither drug altered ADP, collagen, thrombin, or calcium ionophore-induced platelet aggregation or platelet granule secretion. Neither drug prevented formation of thromboxane B2 during secondary aggregation. Verapamil, but not diltiazem, increased the Kd of [3H]yohimbine binding from 2.03 to 46.99 nM without altering the calculated number of binding sites per platelet (124 sites/platelet). Supplemental calcium added to citrated platelet-rich plasma reversed both verapamil and diltiazem-induced inhibition of platelet aggregation. We conclude that, at the concentrations tested, both verapamil and diltiazem are specific inhibitors of epinephrine-induced platelet activation. Clearly, both agents may be acting by preventing epinephrine-induced increases in plasma membrane permeability to calcium. However, the greater potency of verapamil compared with diltiazem with only verapamil binding to alpha2-adrenergic receptors suggests that alpha-blockade represents a significant component of verapamil-induced platelet inhibition.

Benzazepines↗
PubMed1986

Purified plasma factor XIIa aggregates human neutrophils and causes degranulation.

Plasma kallikrein has been shown to aggregate human neutrophils and release human neutrophil elastase. However, neutrophils resuspended in factor XII-deficient plasma released only 30% of the elastase compared with normal plasma. Isolated human neutrophils were aggregated in a concentration-dependent fashion by 0.06 to 0.6 U/mL factor XIIa (0.022 to 0.22 mumol/L). Factor XIIa (0.1 to 1.0 U/mL) also induced neutrophil degranulation as evidenced by a concentration-dependent release of the specific granule protein, lactoferrin, and azurophilic granule protease, elastase. The release of neutrophil elastase was biphasic, reaching 40% of maximum at 15 seconds with maximal release by 90 minutes. The active site of factor XIIa was required, since the synthetic inhibitor, D-Pro-Phe-Arg-CH2Cl, which reacts with an essential histidine, and the natural plasma inhibitor, Cl-inhibitor, which interacts with the critical serine, both inhibit by more than 90% the release of elastase. The heavy chain is also required, since factor XII fragments failed to aggregate neutrophils or stimulate degranulation. Factor XIIa (0.6 U/mL) can completely correct the defect in elastase release evident in factor XII-deficient plasma. These studies demonstrate that factor XIIa, at concentrations potentially obtainable in plasma in disease states, can activate neutrophils, and thus may participate in the inflammatory response.

Cell Aggregation↗