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Biomedical subjects

C G Cochrane

Publications and source records attributed to C G Cochrane.

At least 127 records · Page 7Linked to original sources
PubMed1981

Guinea pig Hageman factor as a vascular permeability enhancement factor.

Hageman factor was purified from guinea pig plasma by successive column chromatography. The guinea pig Hageman factor appeared homogeneous as a single-chain protein on polyacrylamide gels in the presence of sodium dodecyl sulfate (SDS) and beta-mercaptoethanol. The apparent molecular weight was 76,000 daltons by SDS--polyacrylamide gel electrophoresis and 105,000 daltons by gel filtration with a Sephadex G-150 column. Amino acid composition of the guinea pig Hageman factor was similar to that reported for human, bovine, and rabbit Hageman factors. The purified guinea pig Hageman factor, as well as guinea pig plasma, showed strong clotting time correction activity in Hageman-factor--deficient human plasma. The activity could be blocked by the IgG fraction of antiserums against guinea pig Hageman factor raised in rabbits or a goat. The concentration of Hageman factor in guinea pig plasma was determined to be 120 microgram/ml by quantitative radial immunodiffusion assay. The 28,000-dalton active form of Hageman factor (beta-HFa) was prepared from guinea pig Hageman factor by treatment with plasma kallikrein. beta-HFa caused an increase in vascular permeability when injected into guinea pig skin at concentrations as low as 3 x 10(-10) M (0.8 ng). Native, or zymogen Hageman factor did not cause an increase in permeability at concentrations of up to 2 x 10(-7) M. The increased permeability induced by beta-HFa was short lasting, with about a 50% decrease in activity apparent within 6 minutes after intradermal injection. The permeability enhancement activity of beta-HFa was inhibited by pretreatment of beta-HFa with diisopropylfluorophosphate. It may be concluded that active Hageman factor in the interstitial space of guinea pigs acts as a vascular permeability factor of far greater potency than bradykinin.

Animals↗
PubMed1980

Dissemination of contact activation in plasma by plasma kallikrein.

The dissemination of contact activation of plasma was examined by measuring the cleavage of Hageman factor (HF) molecules on two separate sets of kaolin particles, one of which contained all of the components of the contact activation system, HF, prekallikrein (PK) and high molecular weight kininogen (HMWK) in whole normal plasma, and the second set of particles containing only HF and HMWK, being prepared with PK-deficient plasma. After mixing of the particles, cleavage of HF on the second set of particles occurred at a rate similar to that occurring on the first set of particles. This indicated that rapid dissemination and burst of activity of the contact reaction takes place in fluid phase. A supernatant factor, responsibel for the dissemination of the contact reaction, was identified as kallikrein. A rapid appearance of cleaved PK (kallikrein) and HMWK on both the kaolin surface and in the supernate was observed. Within 40 s, > 70-80% of the PK and HMWK in the supernate was cleaved. On the surface, approximately 70% of each radiolabeled protein was cleaved at the earliest measurement. Cleavage of PK by activated HF occurred at least 17 times faster on the surface than in the fluid phase, as virtually no cleavage of PK occurred in fluid phase. Each molecule of surface-bound, activated HF was calculated to cleave at a minimum, 20 molecules of PK per minute. It is concluded that the contact activaton of plasma may be divided into three phases: (a) the reciprocal activation of a few molecules of zymogen HF and PK on the surface, with HMWK acting as cofactor to bring these molecules into apposition; (b) the rapid release of kallikrein into the fluid phase and the continued conversion of PK to kallikrein by each surface-bound molecule of activated HF; and (c) the activation by fluid-phase kallikrein of multiple surface-bound HF molecules, and the cleavage of multiple molecules of MHWK both in fluid phase and on the surface by the soluble kallikrein. The evidence suggests that steps b and c account for a great majority of the generation of contact activation of plasma.

Blood Coagulation↗
PubMed1980

Detection of active kallikrein in induced blister fluids of hereditary angioedema patients.

Six suction-induced blister fluids obtained from five patients with hereditary angioedema (HAE) contained active kallikrein, whereas only two blister fluids obtained from eight normal volunteers contained small amounts of this activity. Kallikrein was present in large amounts of HAE blister fluids as assessed by its ability to liberate smooth-muscle-contracting activity from purified high molecular weight kininogen. It was inhibited by purified antibodies specific for plasma prekallikrein and also by purified C1 inhibitor, but not by antibodies specific for C1s. These observations suggest that activation of the Hageman-factor-dependent pathways occurs in the tissues of HAE patients, and once generated, active kallikrein persists in these tissues.

Blister↗
PubMed1980

Rabbit prekallikrein. Purification, biochemical characterization, and mechanism of activation.

Rabbit prekallikrein (RPK) was purified from rabbit plasma by ion exchange and lectin column chromatography and preparative polyacrylamide gel electrophoresis. A 1500-fold purification was routinely achieved with a final yield of 5-10%. The purified RPK was found to be a glycoprotein with an apparent molecular weight of 88,000. Activation of RPK with either trypsin or rabbit Hageman factor (active) occurs by limited proteolytic cleavage, producing two disulfide-linked polypeptide chains with molecular weights of 55,000 and 35,000. Both chains contain carbohyrate and the 35,000-molecular-weight polypeptide was shown to incorporate [3H]DFP. Activation of RPK in kaolin-treated plasma was shown to proceed by an analogous mechanism yielding 55,000- and 35,000-molecular-weight polypeptide chains.

Amino Acids↗
PubMed1980

Activation of rabbit Hageman factor by homogenates of cultured rabbit endothelial cells.

Rabbit Hageman factor was proteolytically cleaved and activated by a homogenate prepared from cultured rabbit endothelial cells. Cleavage of radiolabeled Hageman factor was monitored by polyacrylamide gel electrophoresis in the presence of sodium dodecyl sulfate. Endothelial cell-mediated cleavage of Hageman factor was demonstrated both in a purified system and in plasma, was time and concentration dependent, and was associated with formation of the characteristic 28,000 M(r) form of active Hageman factor. The rate of cleavage of Hageman factor was not affected by Triton X-100 (Rohm and Haas, Co., Philadelphia, Pa.), hexadimethrine bromide (Polybrene, Aldrich Chemical Co., Inc., Milwaukee, Wis.), hirudin, soybean trypsin inhibitor, or antisera to plasminogen or prekallikrein. However, cleavage was enhanced by kaolin, and was inhibited by diisopropyl-fluorophosphate. The enzyme responsible for cleavage of Hageman factor was localized to the 100,000-g-sedimentable, subcellular fraction of the endothelial cell homogenate and was relatively specific, because neither radiolabeled rabbit Factor XI nor rabbit prekallikrein were themselves proteolytically cleaved by the endothelial cell homogenate. However, when these molecules were incubated with the homogenate in the presence of Hageman factor, both Factor XI and prekallikrein were cleaved, demonstrating that Hageman factor had been activated by the endothelial cell homogenate. Furthermore, the kallikrein generated by endothelial cell homogenate-activated Hageman factor was capable of liberating kinin from high molecular weight kininogen as measured by bioassay. Cultured rabbit endothelial cells, therefore, possess the capacity to activate Hageman factor by proteolysis. This may be one mechanism for Hageman factor activation in vivo.

Animals↗
PubMed1980

The distribution of lipopolysaccharide in normocomplementemic and C3-depleted rabbits and rhesus monkeys.

To examine the role of complement (C3) in determining the fate of lipopolysaccharide (LPS) in vivo, the distribution of LPS was studied in normocomplementemic (NC) and C3-depleted animals (pretreated with cobra venom factor [CoF]) after intravenous injection of highly purified, radioiodinated Salmonella minnesota R595 LPS. After injection of a lethal (250 micrograms) or nonlethal (5 micrograms) dose of LPS in NC and CoF rabbits and a lethal (5 mg/kg) dose of LPS in rhesus monkeys, the LPS disappeared from blood in a biphasic manner. In all cases, a substantial portion of the dose was removed from blood in an initial disappearance phase (t1/2 < 15 minutes), which, in some cases, was accelerated in CoF-treated animals. LPS remaining in blood beyond 30 minutes persisted with a much increased half-life (> 5 hours). Liver contained the major portion (40%) of tissue-bound LPS (determined by use of 131I-BSA blood marker) in animals killed 3--5 hours after injection. The distribution of LPS in rabbits was found to be dose-indpendent and only minimally changed by prior depletion of C3. In addition, the tissue distribution and cellular localization of LPS in monkeys was similar to that we have reported previously for R595 LPS in NC rabbits and was not substantially changed by prior CoF treatment. These results indicate that binding of C3 to intravenously injected LPS is not required for the initial rapid disappearance from blood. Further, the uptake of LPS by cellular targets, notably the hepatic macrophages (Kupffer cells), is not altered by in vivo decomplementation.

Animals↗
PubMed1979

Molecular assembly in the contact phase of the Hageman factor system.

Data obtained in the past few years have defined the molecular mechanisms of contact activation of the Hageman factor pathways of plasma, i.e., the kinin-forming, intrinsic clotting and fibrinolytic systems. Involved are four molecules: Hageman factor, high molecular weight (MW) kininogen, prekallikrein and factor XI. High MW kininogen serves as a surface cofactor to assemble prekallikrein or factor XI in proximity to surface-bound Hageman factor. Reciprocal proteolytic activation of Hageman factor and prekallikrein represents an essential step in the rapid activation of the contact phase. Although Hageman factor does undergo cleavage and activation in the absence of prekallikrein or high MW kininogen, the rate is approximately 50 and 100 times slower than when these molecules are present. Once Hageman factor is activated on the surface, it cleaves and activates clotting factor XI. Activated Hageman factor (HFa) exhibits two molecular forms. One of these, alpha HFa, activates prekallikrein and factor XI, and the intrinsic clotting system on the surface. alpha HFa and clotting factor XI remain surface bound. The other form of activated Hageman factor, beta HFa, leaves the surface, going into solution where it readily activates additional prekallikrein but not factor XI. Of perhaps even greater importance, kallikrein rapidly dissociates from the surface. Thus the formation of bradykinin and fibrinolysis is disseminated whereas clotting via the intrinsic system remains localized. Reviewed here is the molecular mechanism of contact activation of the Hageman factor pathways and discussed in the interaction of Hageman factor with the negatively charged surface, prekallikrein, factor XI and high MW kininogen. The multiple forms of activated Hageman factor and their potential biologic significance are also discussed.

Blood Coagulation↗
PubMed1979

Activation of human Hageman factor by a leukocytic protease.

We earlier reported the IgE-mediated release of a basophil kallikrein of anaphylaxis (BK-A) which, like plasma kallikrein, is an arginine esterase and cleaves human plasma kininogen generating immunoreactive kinin. We herein report that, like plasma kallikrein, preparations rich in this basophil protease also activate human Hageman Factor by proteolytic cleavage of the zymogen molecule into light and heavy chains. These fragments of 28,000 and 52,000 daltons are similar in size to those produced during activation of Hageman Factor by plasma kallikrein. Exposure of Hageman Factor (bound to a negatively charged surface) to BK-A led to the proteolytic cleavage of Hageman Factor producing a 28,000 molecular weight fragment (HFa) which is functionally active and capable of activating prekallikrein to kallikrein. We conclude that, during anaphylaxis, basophils may release a protease that is capable of cleaving and activating Hageman Factor, thus providing a mechanism for initiating the in vivo activation of the Hageman Factor dependent systems.

Anaphylaxis↗
PubMed1978

Surface and fluid phase activities of two forms of activated Hageman factor produced during contact activation of plasma.

The ability of the two forms of activated Hageman factor (HFa) produced during contact activation of plasma to activate prekallikrein and factor XI was studied. alpha-HFa, defined as an 80,000 mol wt two-chain enzyme which remains bound to the surface was capable of cleaving surface-bound prekallikrein and factor XI. beta-HFa, a 28,000 mol wt single chain molecule, released from the surface during contact activation was able to cleave prekallikrein but showed no activity on factor XI. Cleavage of prekallikrein by beta-HFa occurred irrespective of whether the substrate was surface-bound or in solution. Cleavage of factor XI occurred only when it was surface bound and only the alpha-form of HFa was capable of this proteolytic action. Factor XI was found to remain bound to the surface while prekallikrein and kallikrein rapidly dissociated from the surface into the supernate. These findings suggest that the initiation of intrinsic coagulation through the activation factor XI is a localized event occurring at the site of contact activation and is the result of the action of alpha-HFa. By contrast, kinin generation and fibrinolysis resulting from the formation of kallikrein can be initiated either at the site of contact activation, by alpha-HFa action, or throughout the plasma, by beta-HFa; further dissemination of these activities is assured by the rapid dissociation of kallikrein itself from the surface.

Blood Coagulation↗
PubMed1978

Mediating systems in inflammatory disease.

This article reviews the mediation systems participating or potentially participating in inflammatory disease, especially in immunologic injury of the glomerulus. Mediator systems are separated into 3 mechanisms: the first involves complement and neutrophils; the second involves systems unrelated to neutrophils and complement components from C3 to C9; and the third involves blood monocytes. Major emphasis is given to an analysis of factors that potentially participate in the second mechanism. These include humoral factors such as the coagulation system and Hageman factor systems and cellular factor such as platelets or cells resident in the glomerulus. Studies on a role of vasoactive amines are presented. The importance of separating neutrophil-dependent and -independent mechanisms in these studies is emphasized. A review of current knowledge of the biochemical mechanisms involved in the Hageman factor system is presented because of the potential role of these components in the development of inflammation.

Animals↗
PubMed1978

Role of complement in lethal bacterial lipopolysaccharide-induced hypotensive and coagulative changes.

The effect of C3 depletion on the multiple pathophysiological changes produced by a lethal dose of Serratia marcescens lipopolysaccharide (LPS) was evaluated. The injection of this LPS into rabbits resulted in biphasic hypotensive changes and thrombocytopenia. These changes were characterized by an acute, transient decrease occurring within minutes after injection followed by a second more gradual decrease beginning 30 to 60 min post-LPS. Prior depletion of C3, with the anticomplementary protein from cobra venom (CoF), did not alter the extent of either the gradual hypotensive and platelet changes or the coagulative and metabolic changes when normal and C3-depleted rabbits were compared. Importantly, the lethal effects of S. marcescens LPS were not reduced by prior depletion of C3. Only the immediate, reversible thrombocytopenia and hypotension were abrogated by C3 depletion.

Animals↗
PubMed1978

The effect of complement depletion on bacterial lipopolysaccharide (LPS)-induced hemodynamic and hematologic changes in the Rhesus monkey.

Lipopolysaccharide (LPS) isolated from Salmonella minnesota R595 or from Escherichia coli 0111:B4 induces hypotension in rhesus monkeys with normal complement levels. This hypotension is accompanied by decreased total peripheral resistance. The depletion of C3 and terminal complement components by prior intraperitoneal administration of the anticomplementary protein cobra factor did not alter the hemodynamic changes which occur following the rapid injection of 5 mg/kg of R595 LPS, the infusion of 500 microgram/kg of R595 LPS, or the injection of 500 microgram/kg of 0111:B4 LPS. We conclude that the LPS-induced hemodynamic changes in the subhuman primate are medicated by pathways which do not require the participation of C3. The kinetics and extent of the neutropenia and thrombocytopenia resulting from the injection of 0111:B4 or R595 LPS were not latered by prior depletion of greater than 95% of the plasma C3.

Animals↗