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PubMed1967

The conversion of C'IS to C'1 esterase by plasmin and trypsin.

The formation of C'1 esterase from C'1, the first component of complement, may be brought about by the action of plasmin or trypsin upon C'1s, a subcomponent of C'1. These enzymes also decrease the esterolytic activity of C'1 esterase. The formation of C'1 esterase was demonstrated by measuring the appearance of an agent or agents with esterolytic properties and the capacity to inactivate C'2 and C'4, attributes of C'1 esterase. The activity of the agent which evolved was blocked by serum inhibitor of C'1 esterase. The implications of these observations, that the formation of C'1 esterase during complement fixation is mediated by proteolytic processes, are under study. The possible inhibition of C'1q by soybean trypsin inhibitor is in agreement with this hypothesis.

Animals↗
PubMed1986

Endotoxin inactivating activity of rat serum.

The ability of rat serum to inactivate endotoxin (LPS) was assessed with the aid of the limulus amebocyte lysate assay. Following the addition of various amounts of endotoxin to normal serum the mixture was incubated for 1 hr at 37 degrees C and the residual endotoxin activity determined. One milliliter of rat serum inactivated between 5 and 10 micrograms Escherichia coli LPS per hour. Heating serum for 45 min at 56 degrees C resulted in loss of 80-90% of the LPS inhibitor (LPSI) activity. Serum from cobra venom factor (CVF)-treated rats inactivated between 0.5 and 2.5 micrograms LPS/ml serum. Serum from tolerant rats, even after heating for 45 min at 56 degrees C, inactivates between 10 and 15 micrograms LPS/ml serum/hr; decomplemented tolerant rat serum neutralizes between 5 and 10 micrograms LPS/ml serum/hr. Clearly, the tolerant rat has large quantities of LPSI activity, which does not appear to be complement. The inhibitor found in tolerant rat serum is not species specific since it inactivates Salmonella minnesota and Salmonella typhimurium endotoxins to the same degree and in the same amount as E. coli endotoxin, the agent used to induce tolerance. Both heating serum (56 degrees C) and lead acetate reduce LPSI activity.

Animals↗
PubMed1991

[Quality control studies of 3 deep-frozen coagulation-active fresh frozen plasma preparations from various suppliers and a new virus-inactivated lyophilized pooled plasma preparation].

Fresh frozen plasma is the most important therapeutic agent in acquired coagulation disorders. We investigated the quality of three conventional fresh-frozen plasma preparations (groups I, II, IV) and one new virus-inactivated lyophilised pooled plasma preparation (group III). In the new plasma preparation we found a significant reduction in coagulation activity, a significantly higher pH value and a highly significant rise in plasma heparin levels. No significant difference in electrolytes, protein levels and concentration or complement activity was found in any of the groups. In conclusion, unlike conventional fresh-frozen plasma, this new virus-inactivated lyophilised pooled plasma preparation does not seem to be suitable for use in therapy of coagulation disorders.

Antiviral Agents↗
PubMed1991

Complement in vitro inhibition by a low-sulfate chondroitin sulfate (matrix).

In this study, the ability of low-sulfate chondroitin sulfate (Matrix), a glycosaminoglycan that does not exhibit anticoagulant action, to inhibit the activation of complement has been evaluated. Two different in vitro tests were employed: lysis of mouse splenocytes sensitized with monoclonal antibodies and lysis of red blood cells sensitized using a rabbit antiserum towards those cells. In both tests, lyophilized rabbit complement was used as complement source. The low-sulfate chondroitin sulfate Matrix has been compared with a hypersulfated one (Arteparon). Both compounds share anticomplementary activity in vitro although potency appears to be related to the sulfate content of the chondroitin.

Animals↗
PubMed1991

Biochemical studies on sulfated lactobionic acid amides.

A series of sulfated bis-lactobionic acid amides was prepared. The compounds comprise highly charged poly-anions of very low molecular weight. Usually, the compounds contain 16 sulfate groups per molecule and are homogeneous, monodisperse substances. The molecular weights range from 2388 to 2514. The compounds were evaluated for anticoagulant activity using a number of standard tests. The compounds exhibited moderate to good APTT activity. Interestingly, the anti-Xa and anti-IIa activities were very low, particularly in amidolytic assays. Using prothrombin and Factor X activation assays, it was demonstrated that these compounds were more potent in these experimental settings than in standard anti-Xa or anti-IIa assays. Compared with heparin and LMW heparins, the bis-lactobionic acid amides were particularly active as inhibitors of the intrinsic system activation of Factor X. The bis-lactobionic acid amides exhibited potent anticomplement activity, being clearly superior to heparin and LMW heparins. For the most interesting substance, LW 10082, experimental results suggest that its anticoagulant activity is independent of antithrombin II. The anticoagulant activity of LW 10082 was readily neutralized by protamine sulfate. Platelet factor 4, however, did not reduce its anticoagulant activity. Because of these favorable properties, it is hoped that LW 10082 might prove to be an interesting alternative to heparin or LMW heparin in clinical use.

Amides↗
PubMed1988

[Changes in the kallikrein-kinin and complement system in angiography using non-ionic contrast media].

To examine alterations of the kallikrein-kinin system and of the complement due to the bolus injection of newer non-ionic contrast agents, venous blood samples were taken before and 3 min after angiography. There were no adverse contrast reactions clinically evident. Prekallikrein, kallikrein inhibition, beta-factor XIIa inhibition, C1-esterase inhibitor, C1q, C3, ATIII, HMW-kininogen, fibrinogen and factor XII were determined. Bolus injection of the contrast medium caused an activation of the kallikrein-kinin system (p less than 0.05) with reduction of prekallikrein, kallikrein-inhibition, beta-factor XIIa inhibition and C1-esterase inhibitor. The levels of C1q and C3 were also decreased (p less than 0.05) indicating an activation of the complement. Our results demonstrate, that angiography causes a significant activation of the kallikrein-kinin as well as of the complement system in spite of the use of newer non-ionic contrast agents.

Angiography↗
PubMed1979

Adherence, augmented adherence, and aggregation of polymorphonuclear leukocytes.

Adherence of polymorphonuclear leukocytes to nylon fiber was found to be plasma-independent and distinct from the processes of augmented adherence, leukocyte aggregation, and inhibition of random leukocyte migration, all of which are dependent on "activated" plasma. Nylon fibers were unable to "activate" plasma, in contrast to the complement-activating agent zymosan. Prior incubation of plasma with antiserum to the third component of complement (C3) inhibited aggregation of polymorphonuclear leukocytes by plasma incubated with zymosan, and heat-inactivation blocked augmentation of adherence by treatment of plasma with zymosan.

Adult↗
PubMed1991

A potent and specific immunotoxin for tumor cells expressing disialoganglioside GD2.

Monoclonal antibody 14G2a (anti-GD2) reacts with cell lines and tumor tissues of neuroectodermal origin that express disialoganglioside GD2. mAb 14G2a was coupled to the ribosome-inactivating plant toxin gelonin with the heterobifunctional cross-linking reagent N-succinimidyl-3(2-pyridyldithio)propionate. The activity of the immunotoxin was assessed by a cell-free translation assay that confirmed the presence of active gelonin coupled to 14G2a. Data from an enzyme-linked immunosorbent assay demonstrated the specificity and immunoreactivity of the 14G2a-gelonin immunotoxin, which was identical to that of native 14G2a. Assays for complement-dependent cytotoxicity (CDC) and antibody-dependent cellular cytotoxicity (ADCC) revealed that these functional properties of the native 14G2a antibody were also preserved in the 14G2a-gelonin immunotoxin. The gelonin-14G2a immunotoxin was directly cytotoxic to human melanoma (A375-M and AAB-527) cells and was 1000-fold more active than native gelonin in inhibiting the growth of human melanoma cells in vitro. The augmentation of tumor cell killing of 14G2a-gelonin immunotoxin was examined with several lysosomotropic compounds. Chloroquine and monensin, when combined with 14G2a-gelonin immunotoxin, augmented its cytotoxicity more than 10-fold. Biological response modifiers such as tumor necrosis factor alpha and interferon alpha and chemotherapeutic agents such as cisplatinum and N,N'-bis(2-chloroethyl)-N-nitrosourea (carmustine) augmented the cytotoxicity of 14G2a-gelonin 4- to 5-fold. The results of these studies suggest that 14G2a-gelonin may operate directly by both cytotoxic efforts and indirectly by mediating both ADCC and CDC activity against tumor cells; thus it may prove useful in the future for therapy of human neuroectodermal tumors.

Antibodies, Monoclonal↗