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.     

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

Several glycopeptides structurally related to muramyl dipeptide (MDP) have been synthesized and evaluated for their ability to stimulate the non-specific resistance of hamsters against L. 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 x 10(7) 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.     

Effect of synthetic polynucleotides on the growth of transplantable tumours in BALB/c mice.

The effect of BALB/c mice pretreatment with tumour cells (a mammary adenocarcinoma, ADK-1t and an IgA secreting plasmocytoma, MOPC-315) adsorbed with poly I:C, poly I and poly C is examined. Only mice pretreated with cells of both tumours adsorbed with poly I:C and poly C proved to be extensively protected against challenge by homologous untreated tumour cells, whereas this was not so in the case of poly I. A possible explanation of this phenomenon is discussed.     

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.     

Effect of actinomycin D on Trypanosoma cruzi

Viable metacyclic forms of T. cruzi, Y strain, treated with an adequate dose of actinomycin D (50 micrograms Act-D/ml/10(7) parasites/ml for 72 h at 28 degrees C) showed the following properties: 1) they lost their ability to replicate in culture medium, in blood and in tissues of normal mice and were no longer able to incorporate tritiated thymidine; 2) they could not penetrate into Vero cells and could not replicate inside normal macrophages; 3) they retained their immunogenicity and the ability to protect mice against a virulent infection; 4) they did not induce histological lesions as described in chronic experimental Chagas' disease.     

Die anorganischen Bestandteile des Honigtaues vonMegoura viciae Buckt

Summary In the honeydew ofMegoura viciae Buckt., sucking on the sieve tube sap ofVicia faba, the following cations are present in measurable quantities: potassium (13.0–14.1 mg/ml), sodium (0.04–0.051 mg/ml), magnesium (1.8–2.3 mg/ml) and calcium (0.07–0.09 mg/ml). There are only traces of copper, iron, manganese, zinc, cobalt and molybdenum. Amongst the anions, phosphate was found at 1.9–2.5 and chloride at 0.02–0.05 mg/ml, whereas nitrate and sulphate could not be detected.     

Effect of synthetic polynucleotides on the growth of transplantable tumours in BALB/c mice

Summary The effect of BALB/c mice pretreatment with tumour cells (a mammary adenocarcinoma, ADK-1t and an IgA secreting plasmocytoma, MOPC-315) adsorbed with poly I:C, poly I and poly C is examined. Only mice pretreated with cells of both tumours adsorbed with poly I:C and poly C proved to be extensively protected against challenge by homologous untreated tumour cells, whereas this was not so in the case of poly I. A possible explanation of this phenomenon is discussed.This work was supported by a research contract with the Italian National Research Council (C.N.R.).     

Lack of effect of antioxidant therapy during renal ischemia and reperfusion in dogs

Acute ischemic renal failure is of great clinical importance because of its frequent occurrence and the high mortality it causes. Recent observations indicate that reperfusion has its own dangers because of oxygenderived free radicals. To study this problem, ischemia was evoked in dogs in one kidney, by clamping the left renal artery for 45 min. This was followed by a 90-min period of reperfusion when diuresis, GFR, PAH clearance and sodium and potassium excretion were studied. Besides a control group (n=6), the following treatment groups were investigated. Allopurinol (n=7): 50 mg/kg for two days p.o. and 50 mg/kg in physiological saline infusion during the experiment; a small dose of SOD (n=6): 0.5 mg/kg in infusion, started 1 min before reperfusion and given continuously for 10 min; and a high dose of SOD (n=7): 5 mg/kg as above. In the first 15 min following reperfusion, the renal functions significantly worsened in all groups. Later on, the renal functions gradually improved and in the last period after reperfusion, GFR in the ischemic kidney was 64%, cPAH 59%, diuresis 60% and sodium and potassium excretion were 65% and 76%, respectively, of the basal values in the control group.Treatment with free radical scavengers did not cause any considerable changes in the renal functions. In some respects, the worst results were observed with low-level SOD treatment (cPAH, diuresis, as well as sodium and potassium excretion).At the end of reperfusion, there was a significant drop in sodium excretion by the right (intact circulation) kidney of the treated animals.     

Demonstration of "hydroxylase" and "epoxide hydrase" activities in preparations of nucleoli isolated from rat liver]

Aryl hydrocarbon hydroxylase (AHH) activity and epoxyde hydrase (EH) activity have been found in Rat liver nucleoli obtained from untreated (C) and methylcholanthrene (MC) pretreated Rats. Electron microscopic observations of nucleolar preparations did not reveal significant contamination either by intact nuclei or by nuclear membranes. Very low but detectable activity of NADPH cytochrome C reductase was found in the nucleoli. Nucleolar preparations revealed little AHH activity (12-18 pmoles/min/mg). AHH was inducible by MC in nuclei but not in nucleoli. The presence of EH in nucleoli was demonstrated with phenanthrene 9,10-oxide (550-620 pmoles/min/mg) and benzopyrene 4,5-oxide (92-116 pmoles/min/mg). These values were lower than those obtained using intact nuclei. The addition of TCPO (10(-4) M) inhibited EH activity.     

Effect of thiamine hydrochloride on the blood level of 2-formyl 1-methyl pyridinium oxime chloride (2-PAM.C1) in rats.

The biological half-life of 2-PAM.C1 was found to increase in female rats pretreated with thiamine hydrochloride (10 mg/kg i.m.). No such effect was observed in the male rats.     

Chemical sympathectomy reveals pre-and postsynaptic effects of neuropeptide Y (NPY) in the cardiovascular system

Summary Intravenous injection of neuropeptide Y (NPY) caused short-lasting dose-dependent pressor responses in anesthetized rats. NPY was equipotent with noradrenaline in producing proportional pressor effects. Chemical sympathectomy, following the administration of 100 mg/kg 6-hydroxydopamine (6-OHDA), significantly potentiated the systemic pressor effects elicited by NPY or noradrenaline. Pretreatment with 2 nmol NPY enhanced the noradrenaline-induced pressor response in control rats. NPY did not change the basal tension of isolated rat aortic strips but significantly potentiated the contractile activity induced by 16 nM noradrenaline. This effect of NPY was not observed in aortic strips from rats pretreated with 6-OHDA. The presence of pre-and postsynaptic sites of action for NPY in the cardiovascular system of the rat is discussed.     

Chemical sympathectomy reveals pre- and postsynaptic effects of neuropeptide Y (NPY) in the cardiovascular system

Intravenous injection of neuropeptide Y (NPY) caused short-lasting dose-dependent pressor responses in anesthetized rats. NPY was equipotent with noradrenaline in producing proportional pressor effects. Chemical sympathectomy, following the administration of 100 mg/kg 6-hydroxydopamine (6-OHDA), significantly potentiated the systemic pressor effects elicited by NPY or noradrenaline. Pretreatment with 2 nmol NPY enhanced the noradrenaline-induced pressor response in control rats. NPY did not change the basal tension of isolated rat aortic strips but significantly potentiated the contractile activity induced by 16 nM noradrenaline. This effect of NPY was not observed in aortic strips from rats pretreated with 6-OHDA. The presence of pre- and postsynaptic sites of action for NPY in the cardiovascular system of the rat is discussed.     

Effect of Corynebacterium parvum on serum lysozyme (muramidase) levels (author's transl)]

An i.v. injection of 548 microgram of killed Corynebacterium parvum into C57B1 mice leads to significant changes in serum lysozyme (muramidase) levels. After an initial fall at 24 h, the activity of the enzyme increased progressively, reached a peak on the 9th day and returned to control range after the 15th day.     

Renal effects of a high unsaturated fat diet in renal artery stenosis in rats

The renal effects of an unsaturated fat (UNSAT) diet in mild to moderate two-kidney, one-clip (2K1C) renovascular hypertension were evaluated. An UNSAT diet (37% by energy) prevented the development of hypertension compared to 2K1C rats fed a high saturated fat (SAT) (37% by energy) and a normal fat (CONTROL) (11% by energy) diet. Urinary sodium and fractional sodium excretion increased in 2K1C rats as compared to SHAM operated controls, regardless of the diet received. In the early weeks of the experiment (weeks 2–4 post-surgery to induce hypertension), an enhanced natriuresis occurred in the 2K1C UNSAT as compared to the 2K1C CONTROL and SAT diet groups. This resulted from an increase in the glomerular filtration rate (GFR in mls·min^–1) as measured using the single-injection [⁵¹Cr] EDTA method (2K1C UNSAT; 1.99±0.18 versus 2K1C SAT; 1.27±0.09, p<0.02; and versus SHAM CONTROL; 1.45×0.01; p<0.02). The increased GFR was not associated with alterations in effective renal plasma flow (ERPF) as measured using the single-injection [¹²⁵I] Na hippurate method. No differences in sodium excretion; GFR; ERPF or renal blood flow (microsphere technique) were noted between the 2K1C UNSAT and SAT diet groups at weeks 6–8 post-surgery, despite a continued antihypertensive effect of the UNSAT diet. Hence, the antihypertensive effect of an unsaturated fat diet in 2K1C renovascular hypertension in rats is associated with transient glomerular changes leading to an enhanced natriuresis.     

Effect of actinomycin D onTrypanosoma cruzi

Summary Viable metacyclic forms ofT. cruzi, Y strain, treated with an adequate dose of actinomycin D (50 g Act-D/ml/10⁷ parasites/ml for 72 h at 28° C) showed the following properties: 1) they lost their ability to replicate in culture medium, in blood and in tissues of normal mice and were no longer able to incorporate tritiated thymidine; 2) they could no penetrate into Vero cells and could not replicate inside normal macrophages; 3) they retained their immunogenicity and the ability to protect mice against a virulent infection; 4) they did not induce histological lesions as described in chronic experimental Chagas' disease.     

Protective effect of Shigyaku-to,a traditional Chinese herbal medicine,on the infection of herpes simplex virus type 1 (HSV-1) in mice

The antiviral activity of Shigyaku-to (TJS-109), a traditional Chinese herbal medicine, was investigated in mice infected with herpes simplex virus type 1 (HSV-1). TJS-109 is a combination of the medicinal plant extracts fromZingiberis siccatum rhizoma,Aconiti tuber andGlycyrrhizae radix in a specific proportion. Mice infected with a 10 LD₅₀ dose of HSV-1 were treated with TJS-109 orally at doses of 1.25 to 20 mg/kg 2 days before, and 1 and 4 days after the infection. The treated groups had 80% (1.25 mg/kg), 40% (5 mg/kg) and 23% (20 mg/kg) mortality rates 25 days after the infection as compared with a 100% mortality rate in control mice treated with saline. When HSV-1 infected mice (recipients) received CD8⁺T cell fractions derived from spleens of mice treated with TJS-109 (donors), 70% of recipients survived, as compared with 0% survivors in the groups of mice treated with saline, B cell fractions, CD4⁺ T cell fractions or macrophage-enriched fractions prepared from the same donors. TJS-109 did not show any virucidal activities against HSV-1 or any virostatic activities on the growth of HSV-1 in Vero cells. These results suggest that TJS-109 protected mice exposed to lethal amounts of HSV-1 through the activation of CD8⁺ T cells.     

Dietary vitamin E does not protect from endotoxin-induced hepatic microvascular dysfunction

Starting from the concept that lipopolysaccharide (LPS)-associated hepatotoxicity involves the action of reactive oxygen species, the present study was conducted to test whether vitamin E, a lipophilic antioxidant, prevents LPS-induced hepatic microvascular dysfunction and liver injury. Fifty-two rats were divided into three groups and fed diets containing 0 (n=16), 75 (n=18) or 8000 mg (n=18) α-tocopherol acetate/kg food for four weeks. At 1 h and 6 h after intravenous LPS-exposure (10 mg/kg E. coli LPS) hepatic microvascular response and liver injury were assessed by the analysis of Kupffer cell phagocytic activity, leukocyte-endothelial cell interaction and nutritive sinusoidal perfusion (intravital fluorescence epi- illumination technique) as well as bile flow, serum liver enzyme activities and tissue histomorphology. In animals fed with 75 mg vitamin E/kg (standard diet), LPS caused hepatic Kupffer cell activation (increased phagocytic activity) and hepatic microvascular leukocyte activation, with stasis in sinusoids and adherence in postsinusoidal venules (1 h) followed by leukocytic infiltration into tissue (6 h) and progredient sinusoidal perfusion failure (6 h). Hepatic microvascular injury was accompanied by reduced bile flow and enhanced liver enzyme release. Vitamin E-enriched diet (8000 mg/kg) and even vitamin E-deficient diet did not significantly affect LPS-induced hepatic microvascular cell activation and perfusion failure. Thus, we conclude, that vitamin E is not effective to protect from endotoxin-induced hepatic microvascular dysfunction. Received 7 November 1996; received after revision 30 December 1996; accepted 20 January 1997     

Azelastine inhibits bronchial hyperreactivity to acetylcholine in guinea pigs

Contractile responses to acetylcholine were measured using isolated tracheae obtained from actively sensitized guinea pigs 0.5, 1, 5, 20, 24, 48 and 72 h after antigen challenge. Tracheal contractions to acetylcholine and to histamine were significantly increased 20 h but not 0.5, 1, 5, 24, 48 and 72 h after antigen challenge indicating bronchial hyperreactivity. When animals were pretreated with azelastine and then exposed to antigen challenge, concentration-response curve to acetylcholine did not differ from that obtained in control (non-challenged) tracheae. It is likely that azelastine is able to inhibit bronchial hyperresponsiveness to chemical mediators of bronchial asthma.     

Dexamethasone-induced neutrophilia. Negative correlation with increased plasma adrenaline concentrations

Summary Maximal increments in adrenaline and dexamethasone (DXM) plasma concentrations were observed c15 (T₅₀ 40 min) and 30 (T₅₀ 210–240 min) minutes after an i.v. DXM dose (6 mg/m² BSA) in man. There appears, however, to be no direct interaction between these agents in the development of induced neutrophilia, which occurs c240 min postinjection.Acknowledgments. The authors wish to thank Mrs C. Ditzler, Merck Sharp & Dohme Research Laboratories, USA, for determining the plasma dexamethasone concentrations J. M. M. is currently on sabbatical leave from McGaw Laboratories, USA. C. R. B. is a Rhodes scholar.     

Protein synthesis in vivo in muscles of the growing lamb]

The relationship between incorporation of intravenously injected 14C lysine and specific radio-activity of precursor was used to estimate protein synthesis in muscle of growing lambs. The rate of protein synthesis per unit of muscle weight in Supraspinatus and Extensor digitorum longus decreased strongly from one week of age to puberty (10 weeks); afterwards it decreased in supraspinatus and increased slightly in Extensor digitorum longus. The rate of protein synthesis increase in muscle protein weight was constant during the whole experiment (1 week-16 weeks). In preruminant Lambs )1 week-5 weeks) the rate of protein synthesis per unit of muscle weight decreased; however, due to the increase in muscle weight, the rate of protein synthesis in whole muscle remained relatively constant. In order Lambs the rate of protein synthesis in whole muscle decreased. The turnover time of protein increased with age. These results give some explanation on muscular development of Lambs.