Leishmania donovani in hamsters: Stimulation of non-specific resistance by some novel glycopeptides and impact on therapeutic efficacy

Summary Several glycopeptides structurally related to muramyl dipeptide (MDP) have been synthesized and evaluated for their ability to stimulate the non-specific resistance of hamsters againstL. donovani infection. These compounds have been named CDRI compounds. The synthetic procedure used for compounds 86/448 and 84/212 is described.MDP and its synthetic congeners were administered as immunostimulants at a prophylactic dose of 3 mg/kg at two weeks interval. The challenge infection (1×10⁷ amastigotes i.c./hamster) was given in between two doses of the compounds. One of the glycopeptides, CDRI comp. 86/448, has been found to be significantly more potent than MDP, effecting 92% inhibition of the challenge dose, whereas MDP produced only 26.5% inhibition. The effect of comp. 86/448 lasted until day 7 of challenge. The efficacy of sodium stibogluconate was appreciably improved in hamsters treated with comp. 86/448.     

Leishmania donovani in hamsters: Stimulation of non-specific resistance by novel lipopeptides and their effect in antileishmanial therapy

Several novel type of lipopeptides were synthesized and evaluated for their ability to stimulate non-specific resistance againstLeishmania donovani infection. Peritoneal macrophages isolated from young male hamsters treated with muramyl dipeptide (MDP) and various synthetic lipopeptides (6 mg/kg i.p.) 7 days earlier, were cultured in vitro and challenged 24 h later withL. donovani promastigotes. One lipopeptide, Central Drug Research Institute (CDRI) compound 86/450, exhibited significantly higher immunostimulatory activity than MDP. Its prophylactic activity was further confirmed in hamsters by giving 2 split doses of 3 mg/kg of the compound spaced at 2 weeks, i.e. on day –7 and +7 of challenge withL. donovani amastigotes. The prophylactic effect lasted for 7 days following the last treatment with compound 86/450. The antileishmanial action of sodium stibogluconate (SAG) was also found to be enhanced by 16% in hamsters primed with compound 86/450.CDRI Communication No. 5034.     

Increase in the non-specific resistance to infection in mice after oral administration of 2 synthetic glycopeptides with adjuvant activity]

Two synthetic glycopeptides (MurNAc-L-Ala-D-isoGln and MurNAc-L-Ala-D-Glu), having adjuvant activity, were shown to enhance non-specific resistance to infection against K. pneumoniae. These compounds were active by various routes including oral administration and even if administered after the challenge. Two steroisomers lacking adjuvant activity did not protect the infected Mice.     

GABA transporter lysine 448: a key residue for tricyclic antidepressants interaction

The effects of three tricyclic antidepressants (TCAs) and two serotonin selective reuptake inhibitors (SSRIs) have been studied with an electrophysiological approach on Xenopus laevis oocytes expressing the rat GABA (γ-Aminobutyric-acid) transporter rGAT1. All tested TCAs and SSRIs inhibit the GABA-associated current in a dose-dependent way with low but comparable efficacy. The pre-steady-state and uncoupled currents appear substantially unaffected. The efficacy of desipramine, but not of the other drugs, is strongly increased in the lysine-glutamate or -aspartate mutants K448E and K448D. Comparison of I _max and K _0.5GABA in the absence and presence of desipramine showed that both parameters are reduced by the drug in the wild-type and in the K448E mutant. This suggests an uncompetitive inhibition, in which the drug can bind only after the substrate, an explanation in agreement with the lack of effects on the pre-steady-state and leak currents, and with the known structural data.     

The pleiotropic functions of aspirin: mechanisms of action

Recent studies have suggested that aspirin and aspirin-like compounds have a variety of actions in addition to their well-studied ability to inhibit cyclooxygenases. These actions include inhibition of the uncoupling of oxidative phosphorylation, decreases in adenosine triphosphate stores, increases in extracellular adenosine, downregulation of the expression and activity of inducible nitric oxide synthetase, inhibition and/or stimulation of various mitogen-activated protein kinase activities and inhibition of nuclear factor binding κB site (NF-κB) activation. Moreover, aspirin-like compounds have recently been shown to have previously unappreciated clinical and biological effects, some apparently independent of cyclooxygenase. In this review we discuss the various mechanisms of action of aspirin-like compounds and their relevance to clinical disease and therapy. Received 1 February 1999; received after revision 1 April 1999; accepted 7 May 1999     

Ureido-ethyl-imidazolines active against autochthonous diethylnitrosamine-induced epidermoid,papillary and adenocarcinomatous tumors of the respiratory tract of Syrian hamsters and against human bronchogenic carcinomas in nu/nu mice

Summary The detection of a new class of tumor inhibiting substances is described. Employing a chemical reaction discovered several years ago, a series of imidazolinylureas were prepared. It was found that some compounds of this group were active against diethylnitrosamine (DENA)-induced tumours in hamsters. CGP 15 720 A (1-{2-[2-(4-pyridyl)-2-imidazoline-l-yl]-ethyl}-3-(4-carboxy-phenyl)urea,Xb), the most active compound at present, was developed through a series of structural variations. CGP 15 720 A inhibits significantly in oral or parenteral treatment with well tolerated doses (10–30 mg/kg) the progressive growth of autochthonous, DENA-induced papillary, epidermoid and adenocarcinomatous tumors of the respiratory system in Syrian hamsters and prolongs significantly the survival. The substance also inhibits significantly the growth of 2 poorly differentiated human epidermoid or anaplastic bronchogenic carcinomas in nu/nu Balb/c mice and prolongs the mean survival time. In these mice, the substance is also active against the rodent ascites tumors Ehrlich carcinoma, CrSa 180 and Yoshida Sa AH 66, although it is only marginally active or inactive against these tumors in normal mice or rats. — In the therapeutic trials, hamsters tolerated the highest dose administered for 4 weeks, 1000 mg/kg p.o., without signs or symptoms of toxicity.Editorial remarks. There is still an urgent medical need for effective and welltolerated drugs for the treatment of the most common forms of cancer, such as bronchial carcinoma, or for post-operative prophylaxis against relapse and metastasis. — The old-established screening method based on rapidly proliferating acute transplantable lymphatic leukemias in the mouse that is applied in the major cancer research centers has certainly achieved some measure of clinical success, inasmuch as the mean duration of survival of patients with acute lymphatic leukemia has increased from 3 months to about 6 years and similar activity has been found in some rapidly proliferating lymphomas, sarcomas and teratomas.The authors were convinced, however, that chemotherapeutic agents effective against lung cancer could only be found with the help of new specific animal models. They developed a model of an autochthonous tumor in the hamster, applied it in extensive series of experiments, and succeeded in synthesizing and identifying a group of compounds that were both effective and well tolerated. They describe the synthesis and biological activity of CGP 15 720, the compound with the highest therapeutic index and an apparently non-cytotoxic mode of action.     

Spectrum of Aeromonas and Plesiomonas infections in patients with cancer and AIDS

The spectrum of infection with Aeromonas and Plesiomonas included gastroenteritis, bacteremia, biliary tract infection, perirectal infection, and disseminated disease. Most patients (86%) with bacteremia were neutropenic (less than 500 PMN/mm3). Colonization of stools and sputum also occurred. Therapy with aminoglycosides, beta-lactams, trimethoprim/sulfamethoxazole, and the newer quinolones was effective in patients with AIDS and cancer.     

Antidesmanol-a new pentacyclic triterpenoid fromAntidesma menasu Miq. ex. Tul.

Summary Antidesmanol (1), a new pentacyclic triterpenoid, has been isolated along with n-tritriacontane, friedelin, canophyllal and canophyllol from the aerial parts ofAntidesma menasu. Based on chemical and spectroscopic evidence, its structure has been established as 3-keto-16-hydroxyfriedelane. n-Tritriacontane and friedelin have shown antiinflammatory and diuretic activities respectively in experimental animals.CDRI Communication No. 2536.     

Course of fever response to repeated administration of sublethal doses of lipopolysaccharides, polyinosinic:polycytidylic acid and muramyl dipeptide to rabbits

The purpose of the present study was to examine the development of tolerance to three structurally dissimilar pyrogens, i.e., lipopolysaccharide (LPS), muramyl dipeptide (MDP) and polyinosinic:polycytidylic acid (poly I:C) in rabbits. The possibility of pyrogenic cross-tolerance among these agents has also been studied. It was observed that repeated injection of sublethal doses of LPS and MDP was connected with the changing of biphasic fever to monophasic. The consequence of this was a drop in the fever index. In contrast to LPS and MDP, the repeated administration of poly I:C did not result in such changes. Successive injections of this pyrogen always evoked biphasic fever. We also demonstrated that pyrogenic cross-tolerance between LPS and MDP did not occur. The cross-tolerance between LPS and MDP did not occur. The cross-tolerance among pyrogens was possible if they originated from the same class, for example endotoxin from Salmonella abortus eq. and endotoxin from Escherichia coli.     

Nitric oxide-dependent blood-brain barrier permeability alteration in the rat brain

The role of nitric oxide (NO), a well known vasodilator, in the regulation of blood-brain barrier (BBB) permeability is not clear. Therefore, the present study was planned to assess the role of NO-releasing compounds like sodium nitroprusside (SNP) and the active metabolite of molsidomine, SIN-1, as well as a precursor of NO, L-arginine, on this physiological barrier. The permeability was assessed by using several tracers. All three agents increased the permeability of BBB to the tracer. The increase in permeability caused by L-arginine was not blocked by N-nitro-L-arginine methyl ester (L-NAME). L-Arginine-treated brains did not show an elevation of nitrite content, thus ruling out the possibility of NO generation and its involvement in BBB permeability alteration. It is concluded that NO itself causes an increase in the permeability of BBB. However arginine-induced opening is not NO mediated.CDRI Communication Number: 5178.     

Course of fever response to repeated administration of sublethal doses of lipopolysaccharides,polyinosinic: Polycytidylic acid and muramyl dipeptide to rabbits

Summary The purpose of the present study was to examine the development of tolerance to three structurally dissimilar pyrogens, i.e., lipopolysaccharide (LPS), muramyl dipeptide (MDP) and polyinosinic: polycytidylic acid (poly I:C) in rabbits. The possibility of pyrogenic cross-tolerance among these agents has also been studied. It was observed that repeated injection of sublethal doses of LPS and MDP was connected with the changing of biphasic fever to monophasic. The consequence of this was a drop in the fever index. In contrast to LPS and MDP, the repeated administration of poly I:C did not result in such changes. Successive injections of this pyrogen always evoked biphasic fever. We also demonstrated that pyrogenic cross-tolerance between LPS and MDP did not occur. The cross-tolerance between LPS and MDP did not occur. The cross-tolerance among pyrogens was possible if they originated from the same class, for example endotoxin fromSalmonella abortus eq. and endotoxin fromEscherichia coli.     

Effect of diphosphonates on ATP and Pi content,Pi uptake and energy charge of cultured calvaria cells

Summary In previous studies we have shown that glycolysis is strongly inhibited in cultured calvaria cells treated with ethane-1-hydroxy-1, 1-diphosphonate (EHDP) or dichloromethanediphosphonate (Cl₂MDP). This study shows that the energy charge of the adenylate pool, and the ATP and Pi content, were not changed by treatment with diphosphonates except for a slight decrease of ATP and Pi at 0.25 mM Cl₂ MDP. The uptake of Pi was diminished by 50% and 20% in cells treated for 6 days with Cl₂MDP or EHDP, respectively, but not when diphosphonates were present only during the uptake studies.Acknowledgments. We thank Miss B. Wyss for her skilled technical assistance. This work has been supported by the Swiss National Science Foundation (grant Nos 3.725.76 and 3.824.79), by the Procter & Gamble Company, USA, and by the Ausbildungs- und Förderungsfonds der Arbeitsgemeinschaft für Osteosynthese (AO), Chur, Switzerland.     

Resistance of in vivo-selected spontaneously transformed cells and Rous sarcoma virus-transformed cells to macrophage-mediated cytotoxicity.

The cytotoxic activity (CTA) of activated peritoneal macrophages (MP) on variant lines of Syrian hamster embryo (HE) cells of differing malignant characteristics was studied. The target cells were a line of low-malignant cells resulting from spontaneous transformation of HE cells in vitro (STHE strain), and malignant variants selected from them in vivo (STHE-LM-4, STHE-LM-8, and STHE-75/18 strains). In addition, we used cells of the HET-SR-1 strain; these are HE cells transformed in vitro by a tumorigenic Rous sarcoma virus (Schmidt-Ruppin strain, RSV-SR), or the TU-SR strain induced by RSV-SR in vivo. Thioglycollate-elicited peritoneal MP from Syrian hamsters were activated in vitro with bacterial levan, LPS or MDP and used as effector cells. MP-mediated cytolysis was determined by means of a 42-h radioactivity release assay with 3H-thymidine-labeled target cells. We found that only the parental STHE cells were susceptible towards fully-activated MP-mediated CTA. All three of the in vivo-selected malignant variants of the STHE cell sublines, as well as the tumorigenic RSV-SR transformants, were resistant to cytolysis by activated MP. Non-activated thioglycollate-elicited MP did not lyse any of the tumor cells studied.     

Resistance of in vivo-selected spontaneously transformed cells and Rous sarcoma virus-transformed cells to macrophage-mediated cytotoxicity

The cytotoxic activity (CTA) of activated peritoneal macrophages (MP) on variant lines of Syrian hamster embryo (HE) cells of differing malignant characteristics was studied. The target cells were a line of low-malignant cells resulting from spontaneous transformation of HE cells in vitro (STHE strain), and malignant variants selected from them in vivo (STHE-LM-4, STHE-LM-8, and STHE-75/18 strains). In addition, we used cells of the HET-SR-1 strain; these are HE cells transformed in vitro by a tumorigenic Rous sarcoma virus (Schmidt-Ruppin strain, RSV-SR), or the TU-SR strain induced by RSV-SR in vivo. Thioglycollate-elicited peritoneal MP from Syrian hamsters were activated in vitro with bacterial levan, LPS or MDP and used as effector cells. MP-mediated cytolysis was determined by means of a 42-h radioactivity release assay with³H-thymidine-labeled target cells. We found that only the parental STHE cells were susceptible towards fully-activated MP-mediated CTA. All three of the in vivo-selected malignant variants of the STHE cell sublines, as well as the tumorigenic RSV-SR transformants, were resistant to cytolysis by activated MP. Non-activated thioglycollate-elicited MP did not lyse any of the tumor cells studied.     

Monoaminoguanidine prevents sorbitol accumulation,nonenzymatic protein glycosylation and development of kidney lesions in diabetic rats

Summary Monoaminoguanidine administration (25 mg/kg b.wt, i.p. for 14 weeks) to alloxan diabetic rats (blood glucose 250 mg/dl) decreased the nonenzymatic protein glycosylation and sorbitol levels. It prevented development of Armanni-Ebstein tubular lesions, pathological changes in the glomerular capillary tufts and glomerular basement membrane thickening in the kidney.CDRI Communication no. 4694.     

Effect of pectin and cellulose on formation and regression of gallstones in hamsters

Male Syrian hamsters were fed a lithogenic diet containing 7% cellulose or 4.2% pectin. After 50 days, pectin was 76% and cellulose 64% less lithogenic than the control diet. Hamsters fed the control diet for 50 days were maintained on that diet for another 50 days or fed diets containing cellulose or pectin. There was a 52% increase in gallstone incidence in hamsters continued on the control diet and a 9% increase in those on cellulose. Pectin promoted regression of gallstones (by 52%).     

Effect of pectin and cellulose on formation and regression of gallstones in hamsters

Summary Male Syrian hamsters were fed a lithogenic diet containing 7% cellulose or 4.2% pectin. After 50 days, pectin was 76% and cellulose 64% less lithogenic than the control diet. Hamsters fed the control diet for 50 days were maintained on that diet for another 50 days or fed diets containing cellulose or pectin. These was a 52% increase in gallstone incidence in hamsters continued on the control diet and a 9% increase in those on cellulose. Pectin promoted regression of gallstones (by 52%).Acknowledgments. This work was supported, in part, by a grant (HL-03299) and a Research Career Award (HL-00734) from the National Institutes of Health, and by funds from Mary L. Smith and the Commonwealth of Pennsylvania.     

The ecdysteroid agonist/antagonist and brassinosteroid-like activities of synthetic brassinosteroid/ecdysteroid hybrid molecules

A series of synthetic hybrid brassinosteroid/ecdysteroid structures has been assessed for their ecdysteroid agonist/antagonist activities in the Drosophila melanogaster B(II) cell bioassay and for brassinosteroid-like activity in the rice lamina inclination test. Most of the compounds proved inactive for ecdysteroid agonist activity, demonstrating the specificity of the ecdysteroid receptor for compounds closely structurally related to 20-hydroxyecdysone. However, compound 18, with 14alpha-hydroxy-7-en-6-one and 22S-hydroxy functionalities (as in most active ecdysteroids), possessed distinct agonist activity (median effective concentration = 1.4 x 10(-5) M), although this is still almost 2000-fold less active than 20-hydroxyecdysone (25). Compounds 13 and 15 possessed weak agonist activity. Compounds 5, 11 and 14 weakly antagonised the action of 20-hydroxyecdysone (at 5 x 10(-8) M) on B(II) cells. In the brassinosteroid bioassay, most of the tested compounds showed activity. This may reflect the metabolic capability of plant tissue to convert test compounds to more active analogues. However, it is clear that biological activity declines as the structure of the test compound deviates further from that of castasterone (16). Three ecdysteroids (25, 26 and 27) are completely inactive in the rice lamina inclination test. These studies demonstrate the high specificities of the insect ecdysteroid receptor and the plant brassinosteroid receptor and indicate that phytoecdysteroids, even in high concentrations, would not interfere with brassinosteroid signalling pathways in plants where the two classes of compounds co-occur. Equally, brassinosteroids would not interfere with ecdysteroid signalling in insects, especially if one takes into account the low concentrations of brassinosteroids in the diet of phytophagous insects.