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At least 541 records · Page 30Linked to original sources
PubMed1983

[Effect of neurotropic compounds on the transmembrane potential of synaptosomes].

Using the potential-sensitive dye (3,3-dipropylthiodicarbocyanine) [dis-C3-(5)] it has been shown that synaptosomes isolated from the rat brain cortex by the method of Hajôs retain their transmembrane potential (TMP) close to the K+-diffusional one. In the Krebs-Ringer medium containing 5 mM KCl the TMP of the synaptosomes was equal to 70-80 mV. The cytostatics cytochalazine B and colchicine and the peptides leu- and met-enkephalins and tuftcin in concentrations up to 10(-3) and 10(-4) M did not affect the TMP of the synaptosomes. Cytochalazine B in a concentration of 4 X 10(-4) M and over caused synaptosomal aggregation. The neuroleptics aminazine, trifluoroperazine, haloperidol, the antidepressant imipramine in concentrations about 10(-4) M as well as the tranquilizers diazepam and phenazepam in concentrations about 10(-3) M completely depolarized synaptosomal membranes.

Animals↗
PubMedDate not supplied

[Psychotropic properties of the tetrapeptide taftsin and its effect on learning].

Experiments on mice and rats have disclosed that taftsin so far known for its stimulatory action on phagocytosis has psychotropic properties. Taftsin potentiates the motor and orienting activity of the animals, reduces the effects of hexenal, reserpine, potentiates the action of amphetamine and arecoline. It shortens the latent period and time of the reaction during training of the rats in a T-shaped maze, but does not increase the number of the training animals. The effect of taftsin has a biphasic nature and seems likely to be related to the effect on alpha-adrenergic systems of the brain.

Amphetamine↗
PubMed1982

Humoral factors in host defense against microbial invaders.

Normal host defense against microbial invaders depends upon an intact humoral and cellular system of inflammation and specific immunity. The major weapons for killing microbes that invade tissue are phagocytic cells, however, humoral factors enable these phagocytic cells to recognize, migrate toward, efficiently ingest, and kill the invaders. Humoral factors essential for host defense include specific antimicrobial immunoglobulin antibodies and multiple proteins which comprise the complement system. The complement system is the oldest phylogenetically and the most important protein in this system is C3. When C3 is activated on the surface of the microbe, ligan is formed which provides a firm bond between organisms and phagocytic cells. This process is termed opsonization and activated C3/C3b is a highly efficient opsonin. C3b attachment stimulates efficient engulfment by phagocytic cells and most microbes are rapidly killed once they are ingested. Complement may also function as a direct bactericidal factor when associated with specific antibody on the bacterial surface. Neisseria meningitidis and Neisseria gonorrheae are susceptible to this action of complement which requires participation of the terminal proteins of the system C6, 7, 8, and 9. Patients without these terminal components, therefore, are susceptible to systemic infections with Neisseria. Septicemia from Streptococcus pneumoniae and other encapsulated microbial species occurs with greatly increased frequency in patients without spleens. Complement and other as yet unidentified humoral factors which contribute to host defense against microbial invaders appear to be deficient in patients without spleens. Antimicrobial antibodies produced in response to antigenic stimulation by microbes are also essential humoral factors. Effective levels of antimicrobial antibodies develop only after microbes have colonized their host and the immune system has been stimulated and protection is delayed. Once produced, however, specific antibodies are potent opsonins and are effective activators of complement. Highly effective and efficient host defense is present when there are circulating specific antibacterial antibodies and an intact complement system. Septicemia may occur when there is a traumatic portal or entry of an exceptionally large bacterial challenge, however, deficiency of humoral or cellular factors of host defense is frequently involved in the pathogenesis of septicemia. Measures for preventing septicemia in susceptible persons include active immunization with microbial antigens or passive therapy with specific antimicrobial antibodies.

Antibody Formation↗
PubMed1994

Immunosuppressive activity of analogs of tripeptide Lys-Arg-Pro with D-amino acid residues.

Synthesis of four analogs, containing D-amino acid residues, of the tripeptide immunosuppressor Lys-Arg-Pro is described. In addition, acetyl and amide derivatives of this peptide were synthesized. Biological effects of all peptides were studied using a delayed type hypersensitivity (DTH) test. It was found that incorporation of D-amino acid residues in definite positions of the peptide chain gives the substances with immunosuppressive activity. A strong immunosuppressive activity was observed also for all-D-analogs (D-Lys-D-Arg-D-Pro).

Amino Acid Sequence↗
PubMedDate not supplied

[The correlation of the behavioral, bioelectrical and cytobiochemical characteristics of the effect of taftsin].

The complex neurophysiological, biochemical, and histochemical investigation carried out in dogs, cats, rabbits, and rats revealed the effects of taftsin (300 mcg/kg) at the macro- and microlevels within different periods (30 and 75 min) after its intraperitoneal injection. It was shown that after taftsin administration the configuration of evoked potentials was modified, especially, in the visual cortex and the nucleus accumbens. The absolute power of EEG spectra increased in a wide range of brain structures under consideration. Catecholaminergic activity was augmented and serotonin activity suppressed in the sensorimotor cortex and caudate nucleus, the indices of the protein metabolism reciprocally changed in the cortical and subcortical structures. Comparison of taftsin effects at different levels suggests that such effects are mainly caused by the interaction between the dopamine-containing brain structures. The consequence of taftsin administration can be probably interpreted as an intervention into the processes of visual perception.

Animals↗
PubMedDate not supplied

[The characteristics of the anxiolytic action of taftsin and its analog TP-7 on behavior and serotonin metabolism in the brain of rats with chronic deprivation of serotoninergic system activity].

The effect of taftcine (Thr-Lys-Pro-Arg) and its analog TP-7 (Thr-Lys-Pro-Arg-Pro-Gly-Pro) on rat behavior and serotonin brain exchange was studied in 95 adult male Wistar rats neonatally administered with 5,7-dihydroxytriptamine. Intracutaneous administration of both peptides (300 micrograms/kg) was found to result in weakening perception of stress situations; an increase in stability of investigation behavior and normalization of serotonin level in the brain of rats with chronic deprivation of serotoninergic system activity. Anxiolytic and psychostimulant activities of TP-7 are more pronounced than those of tafcine.

5,7-Dihydroxytryptamine↗
PubMed1979

Pepstatin, an inhibitor of acid kininogenases and ascites retardant in neoplastic disease.

Evidence is reviewed that pepstatin, an inhibitor of acid kininogenases such as cathepsin D, may be an effective therapeutic agent in retarding ascites accumulation in certain cancers. The evidence for this conclusion is based on the actions of pepstatin in retarding ascites in six different tumor strains inoculated into various species of mice, as well as the demonstration that cathepsin D activity is reduced in vivo in several organs following pepstatin administration. The latter is significant since we have postulated that ascites formation, in good part, is due to leukokinin formation, which is catalyzed by cellular-released cathepsin D.

Animals↗
PubMed1979

The isolation of leukokinin-H and leukokininogen from human ascites fluid; their properties and role.

The leukokinin-leukokininogen system is a pathological kinin generating system which is catalyzed by acid proteases present in neoplastic cells, white cells and even normal tissues. The components of the human system including leukokinin-H and leukokininogen have now been isolated and characterized. Very specific protease inhibitors of the system such as pepstatin have been found and are now known to prevent "in vivo" the formation of pathological fluids such as neoplastic ascites. Strong evidence has been previously published and additional evidence has been presented here which indicates that pepstatin's actions are related to the inhibition of cathepsin-D in vivo and the inhibition of leukokinin formation. Both leukokinins and leukokininogens have been clearly defined and shown to differ from bradykinin and human bradykininogens. This clearly demonstrates the presence in pathological systems of a kinin-generating system which is separate and distinct from the bradykinin generating system. The importance of the leukokinin-leukokininogen system in disease would seem to be very great. The finding that pepstatin can inhibit the system in vivo opens the way for studies of pepstatin and related protease inhibitors as therapeutic agents in neoplastic disease and protease mediated inflammatory disorders.

Amino Acids↗