Pathological and immunological evaluation of different regimens of praziquantel treatment in a mouse model of Schistosoma mansoni infection

BackgroundOne of the considerable challenges of schistosomiasis chemotherapy is the inefficacy of praziquantel (PZQ) at the initial phase of the infection. Immature schistosomes are not susceptible to PZQ at the curative dose. Here, we investigated the efficacy of different PZQ regimens administered during the initial stage of Schistosoma mansoni infection in mice.Methodology/Principal findingsTwo months-old mice were individually infected with 80 S. mansoni cercariae and divided into one infected-untreated control group (IC) and four PZQ-treated groups: PZQ at 100 mg/kg/day for five consecutive days (group PZQ1), PZQ at 100 mg/kg/day for 28 days (group PZQ2), PZQ at 18 mg/kg/day for 28 days (group PZQ3) and a single dose of PZQ at 500 mg/kg (group PZQ4). The treatment started on day one post-infection (p.i), and each group of mice was divided into two subgroups euthanized on day 36 or 56 p.i, respectively. We determined the mortality rate, the parasitological burden, the hepatic and intestinal granulomas, the serum levels of Th-1, Th-2, and Th-17 cytokines, and gene expression. The treatment led to a significant (p < 0.001) reduction of worm burden and egg counts in the intestine and liver in groups PZQ2 and PZQ3. On 56^th day p.i, there was a significant reduction (p < 0.001) of the number and volume of the hepatic granulomas in groups PZQ2 and PZQ3 compared to group PZQ1 or PZQ4. Moreover, in group PZQ3, the serum levels of IFN-γ, TNF-α, IL-13, and IL-17 and their liver mRNA expressions were significantly reduced while IL-10 and TGF-β gene expression significantly increased. The highest mortality rate (81.25%) was recorded in group PZQ2.Conclusion/SignificanceThis study revealed that the administration of PZQ at 18 mg/kg/day for 28 consecutive days was the optimal effective posology for treating S. mansoni infection at the initial stage in a murine model.     

Prophylactic Effect of Enterococcus faecalis FK-23 Preparation on Experimental Candidiasis in Mice

The prophylactic effects of heat-killed cells of Enterococcus faecalis FK-23 (FK-23 preparation) on experimental candidiasis were investigated in normal and leukopenic mice. In cyclophosphamide-induced leukopenic mice, oral or intraperitoneal administration of the FK-23 preparation at a daily dose of 1.25 or 5 mg/mouse for 3 consecutive days prior to Candida albicans infection significantly prolonged survival periods of the infected mice, and decreased viable counts of C. albicans recovered from their kidneys. In normal mice, the FK-23 preparation administered at dosages ranging from 0.63 to 10 mg/mouse/day for 3 consecutive days was ineffective, while in leukopenic mice, the FK-23 administered orally caused a facilitated recovery in the number of white blood cells including neutrophils. Furthermore, intraperitoneal administration of the FK-23 preparation into mice augmented the anti-Candida activity of immunocompromised peritoneal exudate cells obtained from the animals. These results suggested the potential usefulness of the FK-23 preparation as a prophylactic agent for the management of patients with opportunistic fungal infections.     

Characteristic Immune Response in Peyer’s Patch Cells Induced by Oral Administration of Bifidobacterium Components

We demonstrate immunomodulatory effects, especially those involving murine intestinal IgA secretion, in Peyer's patch cells following oral administration of Bifidobacterium immunomodulator (BIM) derived from sonicated B. pseudocatenulatum 7041. BALB/c mice were administered BIM orally for 7 consecutive days. The PP cells demonstrated upregulated secretion of total IgA including BIM-specific IgA following BIM administration. In observing the response of PP cells co-cultured with BIM, we found enhanced secretion of interferon-γ (IFN-γ) and interleukin (IL)-6 in the CD4⁺ T cells. In contrast, IL-12 secretion by Thy1.2⁻ PP cells was enhanced, but secretion of IFN-γ, IL-5, and IL-6 was not significantly affected. Furthermore, the population of CD4⁺ CD45RB^high T cells in PP increased following oral administration of BIM. These data suggest that CD4⁺ T cells were affected by BIM administration. Overall, the results show that oral administration of BIM induced CD4⁺ PP cells to change their expression of cell surface antigen and cytokine production.     

Antibiotic Treatment in Mice Infected with Japanese Borrelia garinii: Efficacy of Ceftriaxone for Eradicating the Infection Induced by Ixodes persulcatus Tick Bites

We compared the efficacy of three antibiotics (ceftriaxone, erythromycin and clarithromycin) against Borrelia garinii infection in mice. The nymphal ticks of Ixodes persulcatus infected with the strain JEM6 of Japanese B. garinii were allowed to feed on female C3H mice. The mice were treated with each of the antibiotics for 5 consecutive days 1, 3, or 7 weeks after tick detachment. The doses of antibiotics per day were as follows: 5 mg intraperitoneal injection of ceftriaxone, 2 mg intraperitoneal injection of erythromycin and 1 mg peroral administration of clarithromycin. The infection status in treated mice was monitored by culturing their earlobes, hearts and urinary bladders in BSK II medium. Ceftriaxone eliminated borreliae completely; however, a recurrence of infection was observed in mice treated with erythromycin and clarithromycin.     

Reversal of cadmium chloride-induced oxidative stress and genotoxicity by Adhatoda vasica extract in Swiss albino mice

Adhatoda vasica Nees (Acanthaceae) that is used by Ayurvedic physicians possesses some established medicinal properties. Environmental and occupational exposure with cadmium affects the renal system adversely. Cadmium is an established genotoxic agent. In the present study, we evaluated the antioxidant and anticlastogenic efficacy of A. vasica against cadmium chloride (CdCl₂)-induced renal oxidative stress and genotoxicity in Swiss albino mice. A single intraperitoneal dose of CdCl₂ (5 mg/kg BW) resulted in significant (p<0.001) increase in chromosomal aberration and micronuclei formation. Oral administration of A. vasica at two doses (50 and 100 mg/kg BW) for seven consecutive days showed significant (p<0.001) suppression of mutagenic effects of CdCl₂ in plant-pretreated groups. To study the mechanism by which A. vasica exerts its antimutagenic potential, enzymes involved in metabolism and detoxification were also estimated. Cadmium intoxication altered the antioxidant levels and enhanced MDA formation significantly (p<0.001). A. vasica showed significant (p<0.001) recovery in antioxidant status, viz., GSH content, its dependent enzymes, and catalase activity. Prophylactic pretreatment of A. vasica extract in cadmium-intoxicated mice showed marked (p<0.001) inhibition of lipid peroxidation (LPO) and xanthine oxidase (XO) activity. The present findings support that antimutagenic efficacy of A. vasica can be attributed to its restoring effects on antioxidant status and suppression of MDA level formation.     

Artificial Infections of Pneumocystis carinii in the SCID Mouse and their Use in the In Vivo Evaluation of Antipneumocystis Drugs

A model for the in vivo evaluation of antipneumocystis drugs has been developed in SCID mice infected intratracheally with cryopreserved mouse-derived Pneumocystis carinii. The development of a highly reproducible fatal P. carinii pneumonia occured within 10 weeks (mean survival time ± SEM = 72.2 ± 1.2 days). Continuous administration of dexamethasone (2 mg/liter in the drinking water) exacerbated the rate of onset of severe P. carinii pneumonia (mean survival time ± SEM = 63 ± 1.3 days) in SCID mice. The number of cysts per g of lung homogenate (homogenate counts) were maximal with an inoculum of 20,000 cysts at 6 weeks post infection. Homogenate counts correlated with infection scores (graded assessments of immunofluorescent cysts on lung impression smears) suggesting that infection scoring accurately and rapidly reflects the severity of P. carinii pneumonia in SCID mice. These studies led to the development of a drug screening protocol in which Pneumocystis-free female SCID mice (20–25 g) were started on dexamethasone 7 days prior to IT inoculation with a single dose of 20,000 cysts. Drugs were evaluated either for: a) prophylaxis (continuously from day 1 post infection) or b) treatment (from day 21 post infection) until day 42 post infection, when all mice were killed and infection scores determined. Co-trimoxazole (at 250 mg sulfamethoxazole + 50 mg trimethoprim/kg/day) given in the drinking water was found to be highly effective in both the prophylaxis and treatment of mouse P. carinii pneumonia. Co-trimoxazole remained very effective in the prophylaxis P. carinii pneumonia in the SCID mouse at 125 mg sulfamethoxazole + 25 mg trimethoprim/kg/day p.o. and showed some enhancement of efficacy over sulfamethoxazole alone at 125 mg/kg/day p.o., suggesting limited synergy between sulfamethoxazole and trimethoprim. The results presented provide confirmation of the usefulness and predictability of the model.     

Single-bulb garlic oil regulates toll-like receptors and Nrf2 cross-talk and IL-17 production in mice fed with high-fat diet

The present study aimed to evaluate the effect of single-bulb garlic oil (SGO) on toll-like receptors 3 and 4 (TLR3 and TLR 4) and nuclear erythroid factor-like 2 (Nrf2) signaling pathway resulted from a high-fat diet and its underlying mechanism. Twenty-four Balb/c mice allocated into six groups: 1) N: mice fed with standard chow; 2) HFD: mice fed a high-fat diet for 45 days without any treatment; 3) HFD + Simv: mice fed a high-fat diet for 45 days and treated with simvastatin; 4–6) HFD + SGO 100, 200, 400 (mice fed a high-fat diet for 45 days and treated with single-bulb garlic oil at dose: 100, 200, and 400 mg/kg body weight for 30 days), respectively. At the end of treatment, spleen and hepar were isolated. The flow cytometry analysis was performed to analyze the relative number of nrf2, superoxide dismutase (SOD), malondialdehyde (MDA), TLR3, TLR4 and interleukin (IL-17). The results showed that HFD induction significantly reduced Nrf-2 and antioxidant enzyme levels. Furthermore, HFD induction increased TLR3 and TLR4 signaling and IL-17 production. Interestingly, 200 mg/kg BW of SGO increased the relative number Nrf-2 followed by SOD and HO-1 elevation at a dose of 100 mg/kg BW. SGO100 notably decrease the relative number of TLR3 (CD11b⁺TLR3⁺) and TLR4 (CD11b⁺TLR4⁺). The production of IL-17 by CD4 and CD8 were also reduced after receiving SGO at 200 mg/kg BW. This study suggests that the protective effect of SGO treatment on HFD mice was achieved by modulating TLR-Nrf2 cross-talks and decreasing IL-17 production. Our findings support a potential beneficial role of SGO for treating metabolic disease caused by a high-fat diet.     

Fas has a role in cerebral malaria, but not in proliferation or exclusion of the murine parasite in mice

We examined the susceptibility of murine Fas-deficient mutants to malaria infection in order to investigate the role of Fas in an experimental murine model of cerebral malaria (CM). We infected mice of B6 and CBA wild-type and mutant backgrounds with Plasmodium berghei ANKA. The incidence of CM in the mutant mice (B6-lpr, CBA-lpr^cg) was decreased by about 50% compared with wild-type control strains at 2 weeks after infection. We did not observe significant differences of parasitemia during a murine malaria infection with nonlethal Plasmodium yoelii 17XNL between wild-type and lymphoproliferative (lpr) mutant mice of C3H and MRL genetic backgrounds, although B6-lpr mice exhibited significantly higher parasitemia than did B6 mice 12 to 18 days after infection. These results suggest Fas has a possible role in CM but may not play a major role in the proliferation or exclusion of a murine malaria parasite in a nonlethal infection.     

Role of internalization in the pathogenicity of Shiga toxin-producing Escherichia coli infection in a gnotobiotic murine model

We investigated the role of bacterial internalization in the killing caused by Shiga toxin-producing Escherichia coli (STEC) infection using a gnotobiotic murine model. A high number of internalized STEC was found in the colonic epithelial cells of STEC-infected mice by both an ex vivo assay and transmission electron microscopy. Most of these mice were killed within 10 days after infection. However, the implantation of lactic acid bacteria in such mice before infection markedly decreased the number of internalized STECs and also completely protected these hosts from killing by a STEC infection. The inhibition of such internalization by immunoglobulin also prevented the hosts from being killed. The Shiga toxin levels in these hosts indicated an inhibition of the penetration of Shiga toxins produced in the colon to the underlying tissue. These results suggested that the internalization plays an important role in the pathogenicity caused by STEC infection in a gnotobiotic murine model.     

Genotoxic effect of 2,4-dichlorophenoxy acetic acid and its metabolite 2,4-dichlorophenol in mouse.

The cytogenetic effect of 2,4-dichlorophenoxy acetic acid (2,4-D) and its metabolite 2,4-dichlorophenol (2,4-DCP) was studied in bone-marrow, germ cells and sperm head abnormalities in the treated mice. Swiss mice were treated orally by gavage with 2,4-D at 1.7, 3.3 and 33 mg kg(-1)BW (1/200, 1/100 and 1/10 of LD(50)). 2,4-DCP was intraperitoneally (i.p.) injected at 36, 72 and 180 mg kg(-1)BW (1/10, 1/5, 1/2 of LD(50)). A significant increase in the percentage of chromosome aberrations in bone-marrow and spermatocyte cells was observed after oral administration of 2,4-D at 3.3 mg kg(-1)BW for three and five consecutive days. This percentage increased and reached 10.8+/-0.87 (P<0.01) in bone-marrow and 9.8+/-0.45 (P<0.01) in spermatocyte cells after oral administration of 2,4-D at 33 mg kg(-1)BW for 24 h. This percentage was, however, lower than that induced in bone-marrow and spermatocyte cells by mitomycin C (positive control). 2,4-D induced a dose-dependent increase in the percentage of sperm head abnormalities. The genotoxic effect of 2,4-DCP is weaker than that of 2,4-D, as indicated by the lower percentage of the induced chromosome aberrations (in bone-marrow and spermatocyte cells) and sperm head abnormalities. Only the highest tested concentration of 2,4-DCP (180 mg kg(-1)BW, 1/2 LD(50)) induced a significant percentage of chromosome aberrations and sperm head abnormalities after i.p. injection. The obtained results indicate that 2,4-D is genotoxic in mice in vivo under the conditions tested. Hence, more care should be given to the application of 2,4-D on edible crops since repeated uses may underlie a health hazard.     

Antiviral activity of recombinant cyanovirin-N against HSV-1

In this study, a standard strain of HSV-1 (strain SM₄₄) was used to investigate the antiviral activity of the recombinant Cyanovirin-N (CV-N) against Herpes simplex virus type 1 (HSV-1) in vitro and in vivo. Cytopathic effect (CPE) and MTT assays were used to evaluate the effect of CV-N on HSV-1 in Vero cells. The number of copies of HSV-DNA was detected by real-time fluorescence quantitative PCR (FQ-PCR). The results showed that CV-N had a low cytotoxicity on Vero cells with a CC₅₀ of 359.03±0.56 μg/mL, and that it could not directly inactivate HSV-1 infectivity. CV-N not only reduced the CPE of HSV-1 when added before or after viral infection, with a 50% inhibitory concentration (IC₅₀) with 2.26 and 30.16μg/mL respectively, but it also decreased the copies of HSV-1 DNA in infected host cells. The encephalitis model for HSV-1 infection was conducted in Kunming mice, and treated with three dosages of CV-N (0.5, 5 &; 10 mg/kg) which was administered intraperitoneally at 2h, 3d, 5d, 7d post infection. The duration for the appearance of symptoms of encephalitis and the survival days were recorded and brain tissue samples were obtained for pathological examination (HE staining). Compared with the untreated control group, in the 5mg/kg CV-N and 10mg/kg CV-N treated groups, the mice suffered light symptoms and the number of survival days were more than 9d and 14d respectively. HE staining also showed that in 5mg/kg CV-N and 10mg/kg CV-N treated groups, the brain cells did not show visible changes, except for a slight inflammation. Our results demonstrated that CV-N has pronounced antiviral activity against HSV-1 both in vitro and in vivo, and it would be a promising new candidate for anti-HSV therapeutics.     

富硒双歧杆菌缓解5-FU导致的化疗性肠粘膜炎的药效学研究

通过腹腔注射5-FU建立小鼠肠黏膜炎模型,探讨富硒长双歧杆菌(Selenium-enriched Bifidobacterium longum,Se-B.longum)能否改善5-FU所致的小鼠肠黏膜炎。将健康BALB/c小鼠随机分为对照组、5-FU组和Se-B.longum/5-FU组,分别灌胃生理盐水、生理盐水和Se-B.longum(Se0.3 mg/kg BW,1×106bacteria/只)6 d,然后5-FU组和Se-B.longum/5-FU组小鼠均腹腔注射5-FU(250 mg/kg),观察小鼠腹泻及死亡情况,5 d后处死小鼠,计算体重变化、脏器指数及考察肠道组织变化;将健康BALB/c小鼠随机分为对照组、5-FU组和Se-B.longum/5-FU组,分别灌胃生理盐水、生理盐水和Se-B.longum(Se 0.3 mg/kg BW,1×106bacteria/只)6 d,然后5-FU组和Se-B.longum/5-FU组小鼠均腹腔注射5-FU(300 mg/kg),观察小鼠死亡情况,绘制生存曲线。Se-B.longum能缓解5-FU导致的正常小鼠的肠粘膜炎、降低小鼠死亡率。     

Experimental treatment of Neospora caninum-infected mice with the arylimidamide DB750 and the thiazolide nitazoxanide

The cationic arylimidamide DB750 and the thiazolide nitazoxanide had been shown earlier to be effective against Neospora caninum tachyzoites in vitro with an IC₅₀ of 160 nM and 4.23 μM, respectively. In this study, we have investigated the effects of DB750 and nitazoxanide treatments of experimentally infected Balb/c mice, by applying the drugs either through the oral or the intraperitoneal route. In experiment 1, administration of DB750 (2 mg/kg/day) and nitazoxanide (150 mg/kg/day) started already 3 days prior to experimental infection of mice with 2 × 10⁶ tachyzoites. Following infection, the drugs were further administrated daily for a period of 2 weeks, either orally or intraperitoneally. Intraperitoneal injection of DB750 was well tolerated by the mice, but treatment with nitazoxanide resulted in death of all mice within 3 days. Upon intraperitoneal application of DB750, the cerebral parasite load was significantly reduced compared to all other groups, while oral application of DB750 and nitazoxanide were not as effective, and resulted in significant weight loss. In experiment 2, mice were infected with 2 × 10⁶ tachyzoites and at 2 weeks post-infection, DB750 (2 mg/kg/day) was applied by intraperitoneal injections for 14 days. In the DB750-treated group, only 2 out of 12 mice succumbed to infection, compared to 7 out of 12 mice in the placebo-group. DB750 treatment also resulted in significantly reduced cerebral parasite burden, and reduced numbers of viable tachyzoites. Our data suggest that DB750 exerted its activity also after crossing the blood–brain barrier, and that this class of compounds could be promising for the control of N. caninum-associated disease.     

Mating experiment of Microsporum canis and M. equinum isolated from animals with Nannizzia otae

In an attempt to study the influence of iron overload on deep mycotic infection, experimental candidiasis was induced in mice. One group received intravenous injections of colloidal iron (60 mg/kg weight) for three consecutive days before intravenous inoculation of Candida albicans spores (1×10⁷). The other received the same number of Candida spores without iron overload. The animals in both groups were observed for 28 days.The Candida lesions, regardless of iron administration, were located mainly in the kidney. There was a marked difference in mortality between the two groups, i.e., 40% in the group without iron administration and 80% in the group with it. The higher mortality rate in the latter group may be explained by following reasons: (1) increased serum iron and iron saturation (iron is essential to the growth of Candida), (2) decreased phagocytic activity against intravenously inoculated Candida because of the saturation of the phagocytic cells by the preceding colloidal iron administration and (3) enhanced proliferation of Candida, which tends to involve the kidney, exposed to abundant iron in the kidney due to increased excretion.The current experiment showed that excessive iron clearly promoted the proliferation of intravenously inoculated Candida in vivo.     

Reproductive and embryological toxicity of lead acetate in male mice and their offspring and mitigation effects of quercetin

Exposure to heavy metals not only impacts on fertility in males, it may also affect the offspring. The aim of the present study was to examine the toxic effects of lead acetate on fertility in male mice and their offspring, and the potential effect of quercetin on mitigating the likely effects. Experimental mice were randomly divided into three groups and administered with (i) distilled water (control); (ii) lead acetate (150 mg/kg BW/day); (iii) lead acetate (150 mg/kg BW/day) with quercetin (75 mg/kg BW/day). Lead acetate administration in male mice adversely affected their fertility through changes in sperm motility, viability, morphology, maturity, membrane integrity, and intracellular reactive oxygen species (P < 0.05). Similar findings were observed in the offspring of the lead-treated male mice. Early embryonic development and implantation rate were also adversely influenced in both the sires and offspring when male mice were treated with lead acetate (P < 0.05). The data demonstrated that down-regulation of Cks2 (CDC28 protein kinase regulatory subunit-2) in sperm had an association with early embryonic development in lead acetate treated group. In conclusion, lead acetate administration adversely impacted on the fertility of the male mice and their male offspring fertility; on the other hand, paternal quercetin co-administration somewhat ameliorated the adverse effects of lead on male mice and their offspring.     

Anti‐infectious activity of synbiotics in a novel mouse model of methicillin‐resistant Staphylococcus aureus infection

The anti‐infectious activity of synbiotics against methicillin‐resistant Staphylococcus aureus (MRSA) infection was evaluated using a novel lethal mouse model. Groups of 12 mice treated with multiple antibiotics were infected orally with a clinical isolate of MRSA at an inoculum of 10⁸ CFU on day 7 after starting the antibiotics. A dose of 400 mg/kg 5‐fluorouracil (5‐FU) was injected intraperitoneally on day 7 after the infection. A dose of 10⁸ CFU Bifidobacterium breve strain Yakult and 10 mg of galactooligosaccharides (GOS) were given orally to mice daily with the antibiotic treatment until day 28. The intestinal population levels of MRSA in the mice on multiple antibiotics were maintained stably at 10⁸ CFU/g of intestinal contents after oral MRSA infection and the subsequent 5‐FU treatment killed all the mice in the group within 14 days. B. breve administration saved most of the mice, but the synbiotic treatment saved all of the mice from lethal MRSA infection. The synbiotic treatment was effective for the treatment of intestinal infection caused by four MRSA strains with different toxin productions. There was a large difference among the six Bifidobacteria strains that were naturally resistant to the antibacterial drugs used. B. breve in combination with GOS is demonstrated to have valuable preventive and curative effects against even fatal MRSA infections.     

Zinc aspartate suppresses T cell activation in vitro and relapsing experimental autoimmune encephalomyelitis in SJL/J mice

Zinc is an essential trace element with a critical role in normal growth and development and in immune homeostasis. Zinc deficiency impairs both the innate and the adaptive immune system and can be normalized by zinc supplementation. On the other end of the spectrum, high dosages of zinc diminish immune cell functions similar to zinc deficiency. Here, we investigated the influence of zinc aspartate on proliferation and cytokine production of stimulated human T cells and mouse splenocytes in vitro. Furthermore, the effect of zinc aspartate was examined in mice with experimental autoimmune encephalomyelitis (EAE), an animal model of Multiple Sclerosis (MS) with a Th1/Th17 T cell-mediated immunopathogenesis. Zinc aspartate suppressed proliferation as well as IL-2, IL-10 and IL-17 production in stimulated human T cells and mouse splenocytes. Importantly, administration of a medium range dose of 30 μg/day zinc aspartate [1.5 mg/kg body weight (BW)] in a therapeutic manner led to a significant reduction of the clinical severity of the EAE during the first relapse of the disease. A lower zinc aspartate dose (6 μg/day, 0.3 mg/kg BW) had no significant therapeutic effect on the severity of the EAE, while administration of higher zinc aspartate amounts (120 μg/day, 6 mg/kg BW) led to more severe disease. Taken together, our data suggest that zinc aspartate can modulate activation, proliferation and cytokine production of effector T cells in vitro and in vivo and that activated autoreactive T cells may be potential therapeutic targets of tightly controlled zinc supplementation in autoimmune diseases like MS.     

Antimalarial activity of endoperoxide compound 6-(1,2,6,7-tetraoxaspiro[7.11]nonadec-4-yl)hexan-1-ol

Plasmodium falciparum, the major causative parasite for the disease, has acquired resistance to most of the antimalarial drugs used today, presenting an immediate need for new antimalarial drugs. Here, we report the in vitro and in vivo antimalarial activities of 6-(1,2,6,7-tetraoxaspiro[7.11]nonadec-4-yl)hexan-1-ol (N-251) against P. falciparum and Plasmodium berghei parasites. The N-251 showed high antimalarial potencies both in the in vitro and the in vivo tests (EC₅₀ 2.3 × 10⁻⁸ M; ED₅₀ 15 mg/kg (per oral)). The potencies were similar to that of artemisinin in vitro and greater than artemisinin's activity in vivo (p.o.). In addition, N-251 has little toxicity: a single oral administration at 2000 mg/kg to a rat gave no health problems to it. Administration of N-251 to mice bearing 1% of parasitemia (per oral 68 mg/kg, 3 times a day for 3 consecutive days) resulted in a dramatic decrease in the parasitemia: all the 5 mice given N-251 were cured without any recurrence, with no diarrhea or weight loss occurring in the 60 days of experiment. N-251 deserves more extensive clinical evaluation, desirably including future trials in the human.     

Cell viability and immunostimulating and protective capacities of Bifidobacterium longum 51A are differentially affected by technological variables in fermented milks

Aim: To investigate the cell viability of Bifidobacterium longum 5^1A in fermented milks and to study its immunostimulating and protective capacity against Salmonella enterica ssp. enterica serovar Typhimurium infection in mice. Methods and Results: Bifidobacterium longum 5^1A was added to milk fermented with different yoghurt starter cultures, before or after fermentation, and viability was monitored during storage (5°C, 28 days). Resistance to simulated gastric acid digestion was assessed. Fermented milks were orally administered to mice for 10 days followed by oral infection with Salmonella Typhimurium. The number of IgA+ cells in the small and large intestine was determined before infection. Survival to infection was monitored for 20 days. Bifidobacterium longum 5^1A lost viability during storage, but the product containing it was effective for the induction of IgA+ cells proliferation in the gut and for the protection of mice against Salm. Typhimurium infection. Conclusions: Cell viability of Bif. longum 5^1A in fermented milks along storage did not condition the capacity of the strain to enhance the number of IgA+ cells in the gut and to protect mice against Salmonella infection. Significance and Impact of the Study: The uncoupling of cell viability and functionality demonstrated that, in certain cases, nonviable cells can also exert positive effects.     

Chemotherapeutic efficacy of ascofuranone in Trypanosoma vivax-infected mice without glycerol

Ascofuranone, an antibiotic isolated from Ascochyta visiae, showed trypanocidal activity in Trypanosoma vivax-infected mice. A single dose of 50 mg/kg ascofuranone effectively cured the mice without the help of glycerol. Repeated administrations of this drug further enhanced its chemotherapeutic effect. After two, three, and four consecutive days treatment, the doses needed to cure the infection decreased to 25, 12, and 6 mg/kg, so that the total doses administered were 50, 36 and 24 mg/kg, respectively. Ascofuranone (50 mg/kg) also had a prophylactic effect against T. vivax infection within the first two days after administration. This prophylactic activity diminished to 80% by day 3 and completely disappeared four days after administration. Of particular interest in this study was that ascofuranone had trypanocidal activity in T. vivax-infected mice in the absence of glycerol, whereas co-administration of glycerol or repeated administrations of this drug are needed for Trypanosoma brucei brucei infection. Our present results strongly suggest that ascofuranone is also an effective tool in chemotherapy against African trypanosomiasis in domestic animals.