Whether Escherichia coli and Staphylococcus aureus cell wall fractions can trigger the activation of prekallikrein was investigated in a mixture of purified human factor XII, prekallikrein, and high-relative-molecular-weight (Mr) kininogen. After exposure for 30 min to bacterial preparations (0.02-5 mg/ml) at 0 C, lallikrein amidolytic activity was expressed as a percentage of the optimal activation of prekallikrein induced by dextran sulfate. Lipopolysaccharide (LPS) fractions of five E coli strains and lipid A of E coli O111B4 induced 50%-90% optimal activity. However, the polysaccharide fraction induced less than 5% activity. Peptidoglycan and teichoic acid of S aureus induced 70%-100% optimal activity at 5 mg/ml, but protein A did not generate activity. No activation of prekallikrein occurred in the absence of factor XII. Thus, LPS and lipid A of E coli and peptidoglycan and teichoic acid of S aureus can generate kallikrein amidolytic activity in a mixture of purified factor XII, prekallikrein, and high-Mr kininogen.
Amygdalin (D-mandelonitrile-beta-D-gentiobioside) is a cyanogenic glycoside claimed to show anti-cancer activity, sold under the incorrect name "Laetrile". For a sensible discussion of its alleged activity and its established toxicity it is necessary that its fate in the organism is known. The pharmacokinetics of amygdalin have been investigated in the Beagle dog after both intravenous and oral administration. The excretion of amygdalin has also been studied in the rat. Amygdalin concentrations were determined by high performance liquid chromatography in plasma ultrafiltrate and urine. The pharmacokinetics of amygdalin after intravenous administration were compared with those of diatrizoate, a model substance for extracellular volume and glomerular filtration. The amygdalin clearance is significantly larger than that of diatrizoate. The volumes of distribution of both substance are the same. After oral administration only a few percents of the amygdalin dose are systemically available. A part of the oral dose is recovered from the urine as prunasin (D-mandelonitrile-beta-D-glucoside).
The pharmacokinetics of prunasin have been investigated in the dog. The results are compared with results obtained with amygdalin. The volume of distribution and the clearance of prunasin are larger than those of amygdalin. The oral bioavailability of prunasin is approximately 50%, whereas amygdalin is hardly absorbed unchanged.
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