Influence of cytostatic agents on fibrinolytic and proteolytic enzymes and on phagocytosis of guinea-pig leucocytes

1967 ◽  
Vol 23 (10) ◽  
pp. 813-814 ◽  
Author(s):  
J. Prokopowicz ◽  
L. Rejniak ◽  
S. Niewiarowski
Keyword(s):  
Guinea Pig ◽  
Proteolytic Enzymes ◽  
Cytostatic Agents

scholarly journals ASPERMATOGENESIS, ANAPHYLAXIS, AND CUTANEOUS SENSITIZATION INDUCED IN THE GUINEA PIG BY HOMOLOGOUS TESTICULAR EXTRACT

1955 ◽  
Vol 101 (6) ◽  
pp. 591-604 ◽  
Author(s):  
Jules Freund ◽  
George E. Thompson ◽  
Murray M. Lipton
Keyword(s):  
Acetic Acid ◽  
Guinea Pig ◽  
Ammonium Sulfate ◽  
Guinea Pigs ◽  
Anaphylactic Shock ◽  
Proteolytic Enzymes ◽  
Trichloracetic Acid ◽  
Oil Emulsion ◽  
Highly Active ◽  
Water In Oil Emulsion

Guinea pig testicles were extracted with acetic acid; the extract was purified by removing material in consecutive precipitations with 30 per cent saturated ammonium-sulfate, trichloracetic acid, and chloroform. The solution so purified, when administered with complete adjuvants, was highly active in inducing impairment of spermatogenesis in guinea pigs. The activity resisted autoclaving at 15 pounds' pressure for 20 minutes, proteolytic enzymes, and formamide. Anaphylactic shock and cutaneous reaction to the purified homologous extract occurred in guinea pigs sensitized by the extract combined with adjuvants. For the production of aspermatogenesis it was essential to incorporate killed mycobacteria into the water-in-oil emulsion containing the antigen; but anaphylactic sensitization did not require the presence of mycobacteria.

Structural requirements for opioid activity of analogues of the enkephalins

1977 ◽  
Vol 198 (1132) ◽  
pp. 249-265 ◽  
Keyword(s):  
Amino Acids ◽  
Guinea Pig ◽  
Rat Brain ◽  
Binding Affinity ◽  
Receptor Binding ◽  
Vas Deferens ◽  
Proteolytic Enzymes ◽  
Opiate Receptor ◽  
Guinea Pig Ileum ◽  
Mouse Vas Deferens

Structure-activity relations of a series of analogues of the two endo­genous morphine-like peptides, leucine-enkephalin and methionine-enkephalin are examined on the basis of ( a ) effects on the mouse vas deferens and the guinea pig ileum and ( b ) affinities for the rat brain opiate receptor. In the mouse vas deferens, metabolism of the peptides by proteolysis is not a major influence on activity. In contrast, however, brain opiate re­ceptor preparations contain an abundance of proteolytic enzymes, the effects of which can be minimized by conducting opiate receptor binding assays at 0 °C and in the presence of bacitracin. The potentiation of biological activity and opiate receptor binding affinity by replacing the Gly 2 residue in the natural enkephalins by d-Ala, is discussed both in terms of increased stability of the Tyr-d-Ala bond to aminopeptidases and of the stabilization of the peptide conform­ation as present in the receptor-peptide complex. The substitution of the Leu 5 - or Met 5 -residue by the corresponding d-amino acid contributes little to proteolytic stability, which emphasizes that the predominating site at which metabolism occurs is the Tyr 1 -Gly 2 bond. Of the analogues described, [d-Ala 2 , d-Leu 5 ]-enkephalin is the most active peptide in the three assay systems, the mouse vas deferens, the guinea pig ileum and the rat brain opiate receptor preparations. Substitutions by the respective d-amino acids d-Tyr and d-Phe at positions 1 and 4 reduce both the potency and binding affinity and emphasize the importance of stereochemical acceptability at these positions. The promotion of receptor binding by d-amino acids is examined, particularly with respect to implied peptide conformations. The experi­mental data have been analysed for the relative influence of metabolic and conformational factors.

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