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Biomedical subjects

L M Greenbaum

Publications and source records attributed to L M Greenbaum.

At least 55 records · Page 3Linked to original sources
PubMed1979

Further studies of the effect of pepstatin on ascites accumulation in tumor-bearing mice.

Studies were done of the effect of pepstatin on ascites accumulation in mice bearing MM46, Ehrlich, CCM, SN36, L1210, and NTF ascites tumors. When pepstatin was injected subcutaneously at 80 mg/kg body wt before ascites accumulation, it inhibited the accumulation in all strains of the tumors tested. In MM46, CCM and NTF tumor strains there was also a decrease in the tumor cell numbers following pepstatin treatment. Kinetic studies on ascites accumulation with tumor strain MM46 demonstrated that even when pepstatin was injected after ascites accumulation it reduced the ascites volume. A dose-dependent effect was observed in this tumor strain when pepstatin was injected both before and after ascites accumulation. The results confirm previous studies of pepstatin's ability to retard ascites in L1210 and P-815Y ascites tumors and also broaden the concept of the mechanisms by which petstatin may be acting.

Animals↗
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↗
PubMed1977

Pepstatin, an ascites retardant of L1210 tumor-bearing mice.

The effect of pepstatin on the kinetics of ascitic fluid accumulation in L1210 tumor-bearing mice (DBA/2) was observed. Following inoculation of 1.5x10(6) tumor cells, untreated mice reached a peak of fluid accumulation on day 6 and remained at this level until death on day 9. A "lag" phase of 4 days occurred before fluid accumulation was seen. Pepstatin administered SC in a single dose of 80 mg/kg during the lag phase, significantly retarded fluid accumulation as compared to untreated animals. Pepstatin administered following fluid accumulation was much less effective. We concluded that pepstatin prevents fluid accumulation rather than acts as a diuretic agent. The term "ascites retardant" is suggested for the pharmacologic actions of pepstatin, since it prevents fluid accumulation without diminishing the cell count.

Animals↗
PubMed1975

Pepstatin, an inhibitor of leukokinin formation and ascitic fluid accumulation.

Ascites fluid accumulation accompanying a mastocytoma or L1210 murine tumor is significantly retarded following the i.p. or s.c. injection of moderate quantities of pepstatin, a known acid protease inhibitor. No effect on cell count was noted by pepstatin treatment. The probable mechanism by which pepstatin acts is by inhigiting the enzymatic formation of chemical mediators known as leukokinins. These are pharmoacologically active peptiedes having potent permeability characteristics previously described by this laboratory. Leukokinins are formed by cathepsin D-like enzymes present in the invading cells and in the ascites fluid acting on a protein substrate, leukokininogen. present in the ascites fluid. Pestatin inhibits the action of these leukokinin-forming enzymes invitro but has no effect on kallikreins (bradykinin-forming enzymes) in vitro. Human ascites fluid from a patient with ovarian carcioma was found to have a paepstatin-inhibited, leukokinin-generating system, as does the mouse. A 'chemical mediator' theory is proposed for ascites fromation which broadens the previously held theory of lymphatic blockage (Holm-Nielsen) and may explain the recent findings of Hirabayashi and Graham of increased plasma-ascites exchange in peritoneal carcionmatosis. Pepstatin inhibition of chemical mediator formation may represent a new therapeutic approach to ascites fluid accumulation in neoplastic disease.

Animals↗