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PubMed1974

Fletcher factor deficiency. A diminished rate of Hageman factor activation caused by absence of prekallikrein with abnormalities of coagulation, fibrinolysis, chemotactic activity, and kinin generation.

Fletcher factor-deficient plasma is deficient in prekallikrein and therefore generates no bradykinin upon activation with kaolin. It also possesses a diminished rate of kaolin-activable coagulation and fibrinolysis and possesses a defect in kaolin-activable chemotactic activity. These abnormalities are also corrected by reconstitution with purified prekallikrein. Addition of intact activated Hageman factor corrected the coagulation, fibrinolytic, and chemotactic defects and addition of Hageman factor fragments corrected the fibrinolytic defect and partially corrected the chemotactic defect; neither of these corrected the kinin-generating defect. Although the Hageman factor-dependent pathways appear to be initiated by contact activation of Hageman factor, the kallikrein generated activates more Hageman factor; this feedback is necessary for the Hageman factor-dependent pathways to proceed at a normal rate. It is the absence of this feedback in Fletcher factor-deficient plasma that accounts for the diminished rate of activation of Hageman factor and therefore a diminished rate of activation of the coagulation and fibrinolytic pathways. The ability of prekallikrein to correct the coagulation, fibrinolytic, kinin-generating, and chemotactic defects of Fletcher factor-deficient plasma is consistent with the identity of the Fletcher factor and prekallikrein.

Blood Coagulation↗
PubMed1976

[Studies on the demonstration of a factor VIII or IX deficiency by means of partial thromboplastin time].

A report is presented on the performance of the correction of PTT by means of factor VIII and IX deficiency plasma, which may be used at least one year, when preserved in liquid nitrogen. The method allows reliable, qualitative statements to be made about disturbances in the area of the coagulation factors VIII, IX, XI and XII; the small amount of time required for preparing and carrying out these works representing an essential advantage.

Blood Coagulation Tests↗
PubMed2000

Causes of venous thrombosis in fifty Chinese patients.

In a whole year from July 1997 to June 1998, a total of 50 patients with sonogram-proved venous thrombosis who called on our hematology clinic consecutively entered into the study. Their mean age was 59.1 +/- 17.5 years, range 18-83 years, and 29 were male. A series of examinations were performed in order to find out the cause of venous thrombosis. These examinations included antithrombin, protein C, protein S, plasminogen, heparin cofactor II, activated protein C ratio, factor V Leiden mutation, fibrinogen, factors VIII and XII, euglobulin lysis time, 677 C-->T mutation of methylenetetrahydrofolate reductase (MTHFR), prothrombin 20210 (PT 20210) A allele mutation, lupus anticoagulant, anticardiolipin antibody, and complete blood count. Five patients (10%) were found to have malignancy; an inferior vena cava thrombosis in one patient was due to venous compression by hydronephrosis; two patients had lupus anticoagulant; two had varicose veins of legs; two had protein C deficiency; four had protein S deficiency; two had plasminogen deficiency; two had antithrombin deficiency. No activated protein C resistance, elevated factor VIII level, factor V Leiden, PT 20210 A allele or heparin cofactor II deficiency was found in the present study. Homozygous MTHFR 677 C-->T gene mutation was found in 7 patients (14%); one of them also had a plasminogen deficiency. No possible risk factor of venous thrombosis could be found in 24 patients (48%). In conclusion, malignancy and protein S deficiency were the most frequent acquired and congenital causes of venous thrombosis in the Chinese, respectively.

Adenocarcinoma↗
PubMed1984

Correction of clotting factor "deficiencies" in plasma from patients with lupus-like anticoagulants.

Identification of spurious coagulation factor deficiencies that are known to occur in association with lupus-like anticoagulants (LLACs) requires the use of cumbersome laboratory procedures. To determine whether single-stage assays employing the APTT system may be used to identify such artifacts, we measured multiple clotting factor levels by several techniques in plasma of six patients with typical LLACs. While normal activities of factors VIII, IX, XI and XII were measured in only 4/24 APTT assays (17%) employing human plasma substrate, normal factor activities were present in all 24 APTT assays employing bovine, canine or rabbit plasma substrate. Normal factor II, V and X activities were recorded in all but one case in assays that utilized a modified Stypven time, while normal factor VIII levels were determined in 5/6 plasmas when the thromboplastin generation test was employed. These results indicate that the use of heterologous plasma substrates in the APTT system may provide a simple method to identify such coagulation factor "deficiencies".

Animals↗
PubMed1997

Potent blood pressure raising effects of activated coagulation factor XII.

A new pressor protein (NPP) in trypsin-activated human plasma was recently reported, whose blood pressure raising effects in bioassay rats are potentiated 300% after treatment with angiotensin I converting enzyme inhibitors (captopril). Pure NPP showed good N-terminal sequence homology with coagulation factor beta FXIIa, and little of it was present in FXII-deficiency plasmas (> or = 99%, n = 4). The present experiments confirm this in four additional FXII-deficiency plasmas. Further, (i) adding highly purified coagulation FXII, alpha FXIIa, or beta FXIIa fragment restores pressor activity to such plasmas, but only after activation with trypsin. (ii) Such requirement for trypsin suggests that no factor is structurally identical with NPP to begin with but that all can be activated to NPP. (iii) When injected directly by vein, only beta FXIIa is pressor, suggesting closest structural resemblance to NPP and (or) readiest endogenous conversion to NPP. (iv) NPP and beta FXIIa are cardiotonic: they both raise systolic pressure more than the diastolic, with a concomitant increase in heart rate. These observations support NPP's structural relationship with beta FXIIa and connect coagulation and blood pressure mechanisms in a new way, whose significance to the physiology and pathophysiology of blood pressure regulation remains to be established.

Adolescent↗
PubMed2002

Pathways for bradykinin formation and inflammatory disease.

Bradykinin is formed by the interaction of factor XII, prekallikrein, and high-molecular-weight kininogen on negatively charged inorganic surfaces (silicates, urate, and pyrophosphate) or macromolecular organic surfaces (heparin, other mucopolysaccharides, and sulfatides) or on assembly along the surface of cells. Catalysis along the cell surface requires zinc-dependent binding of factor XII and high-molecular-weight kininogen to proteins, such as the receptor for the globular heads of the C1q subcomponent of complement, cytokeratin 1, and urokinase plasminogen activator receptor. These 3 proteins complex together within the cell membrane, and initiation depends on autoactivation of factor XII on binding to gC1qR (the receptor for the globular heads of the C1q subcomponent of complement). There is also a factor XII-independent bypass mechanism requiring a cell-derived cofactor or protease that activates prekallikrein. Bradykinin is degraded by carboxypeptidase N and angiotensin-converting enzyme. Angioedema that is bradykinin dependent results from hereditary or acquired C1 inhibitor deficiencies or use of angiotensin-converting enzyme inhibitors to treat hypertension, heart failure, diabetes, or scleroderma. The role for bradykinin in allergic rhinitis, asthma, and anaphylaxis is to contribute to tissue hyperresponsiveness, local inflammation, and hypotension. Activation of the plasma cascade occurs as a result of heparin release and endothelial-cell activation and as a secondary event caused by other pathways of inflammation.

Anaphylaxis↗
PubMed1987

Inhibition of the activation of Hageman factor (factor XII) by complement subcomponent C1q.

Hageman factor (HF, Factor XII) is activated by glass, collagen, and ellagic acid, and initiates blood coagulation via the intrinsic pathway. C1q inhibits collagen-induced platelet aggregation and adherence of platelets to glass, effects attributable to the collagen-like region of C1q. We examined the actions of C1q on HF activation. Incubation of C1q with HF before addition of HF-deficient plasma extended the activated partial thromboplastin time. Similarly, when glass tubes were coated with C1q before testing, the partial thromboplastin time of normal plasma was increased. C1q reduced the activation of HF by ellagic acid, as measured by the release of p-nitroaniline from the synthetic substrate H-D-prolyl-L-phenylalanyl-L-arginine-p-nitroanilide dihydrochloride, an effect inhibited by monoclonal anti-human C1q murine IgG and by digestion of C1q by collagenase. Thus, C1q inhibits activation of HF in vitro in clot-promoting and amidolytic assays and suggests a regulatory mechanism for the inhibition of coagulation.

Amides↗
PubMed2006

gC1qR/p33 serves as a molecular bridge between the complement and contact activation systems and is an important catalyst in inflammation.

The receptor for the globular heads of C1q, gC1qR/p33, is a ubiquitously expressed protein, which is distributed both intracellularly and on the cell-surface protein. In addition to C1q, this molecule also is able to bind several other biologically important plasma ligands, including high-molecular-weight kininogen (HK), factor XII (FXII), and multimeric vitronectin. Previous studies have shown that incubation of FXII, prekallikrein, and HK with gC1qR leads to a zinc-dependent and FXII-dependent conversion of prekallikrein to kallikrein, a requisite for kinin generation. In addition, these studies showed that normal plasma, but not plasma deficient in FXII, PK, or HK, activate upon binding to endothelial cells (EC), and that this activation could be inhibited by antibody to gClqR. In these studies, we show that incubation of serum with microtiter plate bound gC1qR results in complement activation, as evidenced by the binding and activation of C1 and generation of C4d. However, neither Clq-deficient serum nor a truncated form of gC1qR (gC1qRA74-96), supported complement activation. Taken together, the data strongly suggest that at sites of inflammation, such as vasculitis and atherosclerosis, where gC1qR as well as its two important plasma ligands, C1q and HK, have been shown to be simultaneously present, soluble or cell-surface-expressed gC1qR may contribute to the inflammatory process by modulating complement activation, kinin generation, and perhaps even initiation of clotting via the contact system. Based on these and other published data, we propose a model of inflammation in which atherogenic factors (e.g., immune complexes, virus, or bacteria) are perceived not only to convert the endothelium into a procoagulant and proinflammatory surface, but also to induce enhanced expression of cell surface molecules such as gC1qR. Enhanced expression of gC1qR in turn leads to: (i) high-affinity C1q binding and cell production of proinflammatory factors, and (ii) high-affinity HK binding and facilitation of the assembly of contact activation proteins leading to generation of bradykinin and possibly coagulation through activation of FXI.

Carrier Proteins↗
PubMed1990

Regulation of insulin-like growth factor I and stage-specific levels of epidermal growth factor in stage synchronized rat testes.

Stage synchronization of seminiferous epithelium after withdrawal and replenishment of vitamin A provides a valuable and powerful approach to the investigation of paracrine interactions within the testis. However, since the discovery of this model, little attention has been given to the events surrounding the synchronous reinitiation of spermatogenesis after depletion of vitamin A. Synchronization of spermatogenesis was observed in all animals previously deficient in vitamin A. However, the degree of synchrony observed, as assessed by a ratio of synchrony, decreased markedly with time. The possibility that spermatogenic synchrony decreases with time due to variability of the temporal duration of stages of the cycle of the seminiferous epithelium is supported by this observation. However, long-term studies are required to substantiate this point. After initiation of stage synchrony of spermatogenesis, increased testicular concentrations of epidermal growth factor (EGF) were observed in testes synchronized between stages IX-II than at other stages of the cycle of the seminiferous epithelium. This elevation in testicular EGF concentrations correlated well with mitotic division of type A spermatogonia at stages IX, XII, and XIV of the cycle of the seminiferous epithelium. Previous in vitro studies have implicated an EGF-like factor in the stimulation of type A spermatogonial division in the mouse. A significant increase in testicular insulin-like growth factor I (IGF-I) concentrations was observed in control animals 14 days after the injection of retinol acetate. In vitamin A deficient animals, a marked increase in testicular IGF-I concentrations was observed as compared to age-matched controls. Maximal levels of testicular IGF-I concentrations were present 14 and 28 days and again 126 days after re-supplementation with retinol acetate. No stage dependent changes in testicular IGF-I were observed but the data provided suggest the retinol may be one of the factors involved in the regulation of testicular IGF-I.

Aging↗
PubMed1976

Radioimmunoassay of human Hageman factor (factor XII).

A secific, sensitive, and reproducible radioimmunoassay for human Hageman factor (HF, factory XII) has been developed with purified human HF and monospecific rabbit antibody. Precise measurements of HF antigen were possible for concentrations as low as 0.1% of that in normal pooled plasma. A good correlation (correlation co-efficient = 0.82) existed between the titers of HF measured by clot-promoting assays and radioimmunoassays among 42 normal adults. Confirming earlier studies, HF antigen was absent in Hageman trait plasma, but other congenital deficient plasmas, including those of individuals with Fletcher trait and Fitzgerald trait, contained normal amounts of HF antigen. HF antigen was reduced in the plasmas of patients with disseminated intravascular coagulation or advanced liver cirrhosis, but it was normal in those of patients with chronic renal failure or patients under treatment with warfarin. HF antigen was detected by this assay in plasmas of primates, but not detectable in plasmas of 11 nonprimate mammalian and one avian species.

Adult↗
PubMed1985

Rat plasma high-molecular-weight kininogen. A simple method for purification and its characterization.

High-molecular-weight kininogen has been isolated from rat plasma in three steps in a relatively high yield. The purified preparation gave a single band on sodium dodecyl sulfate-polyacrylamide gel electrophoresis in the absence and presence of 2-mercaptoethanol, and the apparent Mr was estimated as 100,000. On incubation with rat plasma kallikrein, rat high Mr kininogen yielded a kinin-free protein consisting of a heavy chain (Mr = 64,000) and a light chain (Mr = 46,000), liberating bradykinin. The kinin-free protein was S-alkylated, and its heavy and light chains were separated by a zinc-chelating Sepharose 6B column. The amino acid compositions of rat high Mr kininogen and its heavy and light chains were very similar to those of bovine high Mr kininogen and its heavy and fragment 1.2-light chains, respectively. A high histidine content in the light chain of rat high Mr kininogen indicated the presence of a histidine-rich region in this protein as in bovine high Mr kininogen, although this region was not cleaved by rat plasma kallikrein. Rat high Mr kininogen corrected to normal values the prolonged activated partial thromboplastin time of Brown-Norway Katholiek rat plasma known to be deficient in high Mr kininogen and of Fitzgerald trait plasma. The kinin-free protein had the same correcting activity as intact high Mr kininogen. Rat high Mr kininogen also accelerated approximately 10-fold the surface-dependent activation of rat factor XII and prekallikrein, which was mediated with kaolin, amylose sulfate, and sulfatide. These results indicate that rat high Mr kininogen is quite similar to human and bovine high Mr kininogens in terms of biochemical and functional properties.

Animals↗