Robert Steger

Activation of bovine bradykininogen by human plasmin

Abstract Incubation of bovine bradykininogen with urokinase-activated human plasmin produces kinin activity as demonstrated on the isolated guinea pig uterus. In terms of specific activity, the activation of bradykininogen appeared to be similar to that obtained with trypsin. A dose-response relationship was evident. It is suggested that direct activation of kininogen by plasmin may constitute another route, apart from the more major kallikrein pathway, in the formation of kinin.

Comparison of biochemical and immunologic properties of venoms from four hornet species

Abstract Venoms of two American hornets, Vespula maculata (bald-faced hornet) and Vespula arenaria (yellow hornet), and two Old World hornets, Vespa crabro and Vespa orientalis , were investigated for biochemical and immunologic properties. They were similar with regard to enzymatic activities (phospholipase A, phospholipase B, and hyaluronidase) and molecular composition. Analysis of radioallergosorbent test (RAST) results obtained from 30 vespid-sensitive patients suggests extensive cross-reactivity between the venoms of V. arenaria , V. maculata , and V. crabro , but the venom of V. orientalis seems to lack at least one important allergen. Rabbit antisera to each of the four venoms contain precipitating antibodies to all four venoms. Strong cross-reactivity was found between the venoms of V. maculata , V. arenaria , and V. crabro and between V. crabro and V. orientalis . V. orientalis venom cross-reacts weakly with the venoms of both V. maculata and V. arenaria . It is concluded therefore that diagnosis and immunotherapy with commercially available venoms of V. maculata and V. arenaria should be adequate for most patients sensitive to V. maculata , V. arenaria , or V. crabro but probably not for a significant proportion of those individuals primarily sensitive to V. orientalis .

Comparison of vespid venoms collected by electrostimulation and by venom sac extraction

Venoms of three vespid species, yellow jacket, bald-faced hornet, and yellow hornet, obtained by either electrostimulation of venom sac extraction were compared with regard to their enzymatic activity, antigenicity, and allergenicity. Phospholipase a, phospholipase B, and hyaluronidase enzymatic activities were present in all six preparations. The activity of venom sac extracts lay in the range found in different batches of venoms obtained by electrostimulation for each species. Analysis of sera from vespid-sensitive patients in the radioallergosorbent test (RAST) with discs coupled with either venom sac extracts or venoms obtained by electrostimulation showed a good correlation of the results within all three species (r = 0.95). In RAST inhibition the potency of venom sac extracts and venom obtained by electrostimulation was similar for each species. Analysis of rabbit antisera to the six preparations revealed similar patterns in immunoelectrophoresis and identity reactions between the major antigens within each species. Tissue protein contamination was detected in all venom sac extracts but not in venoms obtained by electrostimulation.

Immunologic and biochemical evaluation of the potency of whole insect body extracts

Recent studies have indicated that currently available whole body extracts have little potency and are ineffective for diagnosis and treatment of stinging insect allergy. Pure venom is a potent effective allergen but is difficult to obtain in sufficient quantities from all Hymenoptera species. In these studies, an attempt was made to prepare a potent whole body extract. Whole bee body extracts were prepared with different extraction periods and at cold and room temperatures. Potency was examined biochemically by measurements of phospholipase A (PLA) activity and immunologically by PLA and bee venom radioallergosorbent test (RAST) inhibition experiments and gel diffusion studies with the use of rabbit antisera. All extracts prepared in the laboratory had some potency, indicating that it is possible to make a whole body extract containing small quantities of PLA or bee venom. However, the potency of these extracts was minimal as compared with bee venom. Three commercial extracts were almost devoid of detectable immunologic activity. While further attempts may be made to prepare a potent whole body insect extract, these results suggest that it is necessary to obtain venom in relatively pure form for the diagnosis and treatment of stinging insect allergy.

Studies of Chemically Modified Honeybee Venom I.

Allergens of honeybee venom (BV) were modified by formaldehyde treatment (F), acetoacetylation (A) or coupling to polyethylene glycol (P). The biochemical, toxicologic and immunologic properties of these modified BV preparations were analyzed. F showed strongly reduced cytotoxicity, enzymatic activity and reactivity with human BV-specific IgE antibodies but retained the reactivity to BV-specific human and rabbit IgG. In A, enzymatic activity, cytotoxicity and the reactivity with human IgE and rabbit IgG antibodies were only moderately reduced. P lacked enzymatic activity and cytotoxicity and showed only minimal reactivity with IgE and IgG antibodies to BV.

Fibrinolysis and Vasoactive Peptides in Anaphylaxis

During the complex sequence of events in allergic and anaphylactic states, proteases, anticoagulants, histamine, 5-hydroxytryptamine, catecholamines, hypotensive polypeptides, and many other biologically active principles may appear in different animal species. The mechanism of activation and/or release of these factors is understood poorly, as are their respective roles in the biochemical chain of events in different types of shock.

Effect of Heparin on the Kinin-Forming Activity of Trypsin, Plasmin, and Various Kallikreins

Conclusion The effect of heparin on the kinin-forming activity of trypsin, plasmin, and kallikrein from human plasma, dog salivary gland, and dog plasma was studied. Heparin at concentrations of 5 units/ml was a potent inhibitor of dog plasma kallikrein. This inhibitory activity was equivalent to 500 units of Trasylol or 0.1 mg soya bean trypsin inhibitor. At high concentrations (2000 units/ml), heparin inhibited 80% of human plasma kallikrein activity and 40% of dog salivary kallikrein activity. The kinin-forming activity of neither trypsin nor human plasmin was inhibited.

The fibrinolysin system in otitis media with effusion.

Middle ear effusions can cause the fibrinolytic dissolution of human fibrin clots. The data presented herein indicate that the highest level of fibrinolytic activity and general proteolytic activity is found in the serous effusions. The mucoid effusions show the lowest levels of fibrinolytic activity. The significance of the fibrinolytic activity in middle ear fluids is not fully understood. Plasmin, the active protease of the fibrinolysin system, is capable of activating a number of proteolytic systems, including the intrinsic coagulation system, the vasoactive peptide system, and the complement system. All the inflammatory mediator systems can promote increased vascular permeability, tissue edema, and leukocytic migration. The relation of these systems to inflammation in the middle ear may have a profound influence on the possible conversion of a simple middle ear effusion into chronic otitis media.

Acid Dependent Kinin-Forming System in Mammalian Malignant and Normal Tissue

Previous studies have demonstrated that a mammalian tumor (Murphy-Sturm lymphosarcoma) contains the following components of a vasoactive kinin-forming system: kininogen, a kinin-destroying enzyme, and a pre-kallikrein proenzyme capable of being activated by acetone (1). Levels of kininogen increased during tumor development as did kininase activity. Acetone-precipitated tumor extracts formed kinin when incubated with heated (80°C rat) or human plasma. This kinin-forming activity initially increased during tumor growth and then diminished to almost zero levels within 12–14 days following tumor transplant. The kallikrein activity was similar to that of rat plasma kallikrein with respect to pH profile, kinetics of kinin formation (using human plasma kininogen as substrate at pH 7.8), and action of plant, mammalian, and synthetic protease inhibitors.

Comparative acute oral toxicity of sodium warfarin and microcrystalline warfarin in the Sprague-Dawley rat.

Summary The acute oral toxicities of sodium warfarin and a microcrystalline form of acid (enol) warfarin (MICROFARIN) were compared in male and female Sprague-Dawley rats. The drugs were administered in carboxymethylcellulose by gastric needle, and the rats were observed for a 14-day period. The LD 50 , calculated on the basis of probit-log plots and formulae, according to Bliss, for sodium warfarin was 100.3 ± 1.5 mg/kg (0.3037 mmol/kg) for male rats and 8.7 ± 1.2 mg/kg (0.0263 mmol/kg) for female rats. The LD 50 for microcrystalline warfarin for male rats was 112 ± 1.6 mg/kg (0.363 mmol/kg) and 10.4 ± 1.1 mg/kg (0.00337 mmol/kg) for female rats. Both warfarin preparations exhibited the same range of toxicity; the toxicity for both drugs was approximately 10 times greater in the female than in the male rat. Except for the highest dose of warfarin preparations studied (320 mg/kg), the period of highest mortality was between the 4th and 10th post-treatment day. Autopsy revealed hemorrhages into the intestine, thoracic cavity, peritoneal cavity, and urinary bladder. The data show that the microcrystalline form of warfarin is absorbed from the gastrointestinal tract and that its LD 50 is similar to that of sodium warfarin.