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Guanylthiourea (GTU) derivatives were identified as possible anti-malarial agents, recently, using in vitro studies on Plasmodium falciparum. This article gives an account of the in vivo anti-malarial activity of GTU derivatives against experimental rodent malaria. A total of 20 synthesized GTU derivatives were evaluated for in vivo antimalarial activity, out of which six showed encouraging results; one compound appeared to have curative potential. Molecular docking and molecular dynamics analysis were carried out to understand the molecular level interactions.

Visceral leishmaniasis (VL) is a neglected tropical parasitic disease in humans caused by protozoan parasite Leishmania donovani and transmitted to humans by the bite of an infected female sand fly, a haemoflagellate vector. According to WHO, every year 0.7–1 million leishmaniasis cases are reported globally, and over 20,000–30,000 deaths occur. Current anti-leishmanial drug (pentavalent antimonials, miltefosine, amphotericin B, pentamidine and paromomycin) therapy is fraught with several problems and causes serious adverse effects, which limit their clinical application. The emergence of drug resistance and non-availability of an effective vaccine(s) against leishmaniasis poses a serious challenge to leishmaniasis treatment and control. Environmental and socio-economic status of people like deforestation, global warming and poverty exacerbates both parasite survival and disease progression. Pentavalent antimonial-resistant strains of L. donovani are rampant in Bihar, a highly endemic zone of VL in India. Development of co-infections (HIV-VL and Malaria-VL) often leads to poor diagnosis and treatment. There are no proper prognostic and diagnostic markers for VL. Therefore, there is an urgent need for the development of new anti-leishmanial drugs for the treatment and control of devastating VL. Effective immunotherapy/immuno-chemotherapy is considered as a viable alternative to chemotherapy. Cytokines (granulocyte-macrophage colony-stimulating factor, interferon-γ and interleukin-12) both stand-alone and in combination with current anti-leishmanial drugs are being thought to reduce the drug resistance and useful in VL treatment. The development and availability of the reliable models for anti-leishmanial drug screening is very much warranted.

BACTEC 460 has now been phased out, so the search for an alternative is imperative. We have determined the activity of standard anti-tuberculosis drugs against intramacrophage Mycobacterium tuberculosis, in vitro, by using BACTEC 460 and MGIT 960 methods. The minimum inhibitory concentrations of isoniazid, rifampicin, ethambutol and streptomycin against intracellular M. tuberculosis H37Rv were found to be 0.2, 0.8, 8.0, and 5.0 μg/mL, respectively, by both methods. These results show a significant (p

Globally, vaccines have emerged as one of the most effective, safe, and cost-effective public health interventions, and are known to save 2–3 million lives, annually. However, despite various commendable efforts, a suitable human malaria vaccine is yet to see the light of the day. The lack of our complete understanding of the molecular mechanisms of pathogenesis and immune protection in malaria appears to be responsible for this state. Earlier, our laboratory has reported that Swiss mice vaccinated with Plasmodium yoelii nigeriensis-total parasite antigens soluble in culture medium and saponin, following a 100% lethal challenge, showed 60% protection. The monoclonal antibodies (MAbs) generated from the splenocytes of these vaccinated/protected mice, following characterization by in vitro merozoite invasion inhibition assay, ex vivo macrophage phagocytosis assay, and in vivo passive transfer of protection test, belonged to 2 distinct groups—a larger group of MAbs inhibited

Tuberculosis (TB) has overburdened humans for ages and continues to be a major health problem worldwide. Mycobacterium tuberculosis, a facultative intracellular pathogen, is the causative agent of human TB. M. tuberculosis has an enormous capacity to survive and multiply inside host macrophages (MΦs), which are one of the most hostile cell types of the host. MΦs play a central role(s) as an effecter cell in host defense against mycobacterial infections. Soon after the inhalation of droplet-nuclei containing M. tuberculosis by the host, MΦsare the first cells to interact with mycobacteria, leading to the onset of primary events which later ensue in the development of TB. MΦs, all by themselves, are not sufficient to provide protective immunity; they require interaction with other cells (e. g. T-cells) to mount an enhanced protective immune response against the pathogen. The cytokines such as interferon gamma and tumor necrosis factor alpha etc. Play a major role in the regulation of interactions among different cells of the immune system to augment immunity. In this review, we focus on various functional roles of cytokines which serve as a link between innate and adaptive immunity, and discuss their potential use as biomarker(s) or biosignatures for the diagnosis, to monitor the progression of disease, and to determine the success of the treatment of human TB.

Three new series of 8-aminoquinolines with modifications in the side-chain by conjugation with amino acids, dipeptides and pseudodipeptides have been synthesized. The synthesized compounds were tested for in vitro antimalarial activity against chloroquine-sensitive and chloroquine-resistant Plasmodium falciparum strains, in vitro cytotoxicity in mammalian kidney cells (Vero), in vitro antileishmanial activity against Leishmania donovani, in vitro antimicrobial activity and in vitro inhibition of β-haematin formation. The promising compounds were also evaluated for in vivo blood-schizontocidal antimalarial activity against Plasmodium berghei infected mice. The analogues 55 and 101 produced highest antimalarial activities, in vitro. Analogues 52 and 59 exhibited promising antileishmanial and broad spectrum of antifungal activities, respectively.

Mycobacterium tuberculosis exhibits latent state due to its ability to survive for extended periods under oxygen depletion conditions. The conventional plating method employed for in vitro screening of antitubercular agents against latent state M. tuberculosis is laborious and time consuming exercise. Towards this end, BACTEC 460 TB system of antitubercular screening was evaluated for testing efficacy of antimicrobial agents in hypoxia induced model of latent tuberculosis, in vitro . In this study, drugs like isoniazid, metronidazole and rifampin were tested at concentrations— 2, 10 and 50 μg/ml for their antilatency activity by using BACTEC and conventional methods. Results obtained from both the methods were comparable ( P > 0.05) and a good correlation was observed between colony forming units and growth index values. Further, time to determine mycobacterial growth was significantly reduced ( P ≤ 0.001) in BACTEC method (4–7 days) as compared to plating method (26–30 days). BACTEC method was found to be faster, cost effective and more sensitive as compared to plating method. Being rapid, reliable and reproducible, this method can be a promising alternative to conventional plating method for screening of potential antitubercular agents in in vitro models of latent tuberculosis.

Serum amyloid P-component (SAP), a pentraxin, is known to play an important role in innate immunity to microbial infections; however, nothing is known about it during tuberculosis (TB). Mice intratracheally infected with Mycobacterium tuberculosis Erdman, showed peak SAP levels (442+/-58.2 microg/ml) on day 21, which declined to background levels by day 60. Their serum interleukin-6 levels paralleled SAP levels, whereas, their serum transforming growth factor-beta levels were paradoxical. During the acute phase of infection, the SAP levels positively correlated with the lung mycobacterial load. Purified mouse SAP (1-50 microg/ml) treatment of M. tuberculosis-infected alveolar macrophages (AMs), in vitro, inhibited their intracellular mycobacterial growth; maximum inhibition (1.1 log10 CFU reduction) occurred at 10 microg/ml, and a 4-day treatment appeared optimal. Treatment of AMs with both rabbit anti-mouse SAP polyclonal antibody and mannose-derived simple sugars, separately, blocked the SAP-induced inhibition of mycobacterial growth. The mycobacterial growth inhibition appeared to be nitric oxide (NO)-dependent as NO synthase inhibitors, both aminoguanidine and N(G)-monomethyl-L-arginine, annulled it. Further, SAP treatment of infected AMs induced significant (P0.05) elaboration of nitrite (72.1+/-8.3 nM/ml), compared to the controls, and these AMs showed augmented expression of inducible NO synthase. This first study demonstrates that during murine TB the SAP levels were increased, and purified mouse SAP inhibited the intra-AM M. tuberculosis growth, in vitro, apparently via NO-dependent mechanism(s). SAP may thus contribute both to the pathogenesis and pulmonary innate immunity in TB.

We have earlier shown that recombinant mouse granulocyte-macrophage colony-stimulating factor (rmGM-CSF) and methionine-enkephalin co-treatment can protect mice from malaria. We now report the bioimmunotherapeutic effect of rmGM-CSF and a synthetic enkephalin fragment peptide Tyr-Gly-Gly (TGG) co-treatment on blood-induced Plasmodium berghei infection in Swiss mice. Mice were completely aparasitimic following co-treatment with rmGM-CSF (10.0 microg/kg) and TGG (2.0 mg/kg x 3 per day, intraperitoneally (i.p.)) starting from day -1 to day +4; however, in monotherapy, neither of these agents showed any detectable bioimmunotherapeutic effect. Curiously, similar co-treatment with rmGM-CSF (10.0 microg/kg) and higher doses of TGG (10.0 mg/kg) did not protect the mice. The combined bioimmunotherapeutic effect of these agents was abrogated by the separate administration each of rabbit neutralizing anti-rmGM-CSF antibody, non-selective opioid receptor antagonist naltrexone (10.0 mg/kg x 6 per day, i.p.), and silica (3.0 mg per mouse, intravenously (i.v.)). The peritoneal and splenic macrophages from the protected mice showed a significant (P0.05) increase in their pool-size and the phagocytic activity, ex vivo. Furthermore, the protected mice, as compared to the unprotected ones, showed a significant (P0.05) maximum increase in their serum nitrate and nitrite, interferon-gamma (IFN-gamma), and tumor necrosis factor-alpha (TNF-alpha) levels in their splenic homogenates, on the day before the beginning of the resolution of parasitaemia. Selective inhibitors of both inducible (aminoguanidine) and all forms (L-N(G)-monomethyl arginine) of nitric oxide (NO) synthase, significantly (P0.05) augmented the mortality of co-treated mice, suggesting the role of NO in protection. These data show that, in P. berghei-infected mice, co-treatment with rmGM-CSF and conditional doses of TGG can impart protection, apparently through partly NO-dependent and macrophage-mediated mechanism(s).

We report in vitro antimalarial activities against chloroquine sensitive and resistant Plasmodium falciparum strains, and in vivo activities against Plasmodium berghei in mice for four series of ring-substituted- l -histidines and histamines.

Objective: The effect of morphine on host defense during Leishmania donovani infection in golden hamsters was studied. Methods: Hamsters were intracardially infected with L. donovani amastigotes and then monitored by spleen touch print microscopic examination. Morphine and naloxone were administered subcutaneously and intraperitoneally, respectively. Leukocytes were counted by a hemocytometer, and ex vivo phagocytosis was determined by the examination of stained adherent macrophages. Results: Low doses of morphine, 1.75 and 2.5 mg/kg × 2, administered subcutaneously on day 0 and day 15 significantly (p < 0.05) suppressed the infection, whereas high doses (20.0 and 50.0 mg/kg × 2) exacerbated the infection. On day 30, hamsters treated with low doses of morphine showed a significant (p < 0.05) increase in the number of circulating leukocytes and the pool size and phagocytic activity of peritoneal macrophages ex vivo; in hamsters treated with high doses, all these parameters appeared to be diminished. The bone marrow of morphine-treated hamsters showed a fall in total cellularity and no change in the number of monocytes; however, in those treated with low doses, the infection was completely eliminated by day 30, and paradoxically, a significant (p < 0.05) potentiation of infection was observed in hamsters treated with high doses. The spleens of hamsters treated with both low and high doses of morphine showed a significant (p < 0.05) decrease and increase in weight, respectively; treatment with low doses also caused an almost 2-fold increase in the percentage of monocytes. Morphine apparently exerted its protective effects via naloxone-sensitive opioid receptors; naloxone pretreatment did not affect the potentiation of infection. Conclusion: Conditional doses of morphine apparently biphasically modulated the course of L. donovani infection in hamsters, at least in part through macrophage-mediated mechanisms.

Human amoebiasis causes highest number of deaths due to any parasitic disease after malaria and schistosomiasis. Entamoeba histolytica/Entamoeba dispar, the causative parasites, exist in two forms: the highly active and invasive trophozoites and the infective cysts. The disease is transmitted by faecal-oral rout, oral-rectal contamination and by the ingestion of infective cysts in drinking water and food etc. Metronidazole, the most commonly used drug for the treatment of symptomatic amoebiasis, is fraught with several problems including emergence of resistance by E. histolytica. The prevention of the disease through improved sanitation and drinking water quality are some of the most effective means to control the disease. Additionally, the role(s) of mothers, proper hand washing and maintenance of good personal hygiene are also important in the containment of the disease.

Background Human tuberculosis (TB), a chronic inflammatory disease is caused by Mycobacterium tuberculosis, a facultative intramacrophage pathogen. The highly complex interactions between mycobacteria and macrophages (MΦs), characterized in part by the induction and elaboration of several cytokines including IL-1, IL-6, IL-10, IL-12 p40 and IL-12 p70 are not yet fully understood. The cytokines are known to have important bearing on the pathogenesis and host defense during TB. We thus studied different patterns of cytokines elaborated by mouse peritoneal macrophages (PMs) following their interaction with live and heat-killed, virulent and avirulent, and pathogenic and non-pathogenic mycobacteria, in vitro. Materials and methods Pathogenic M. tuberculosis H37Rv (virulent) and M. tuberculosis H37Ra (avirulent), and non-pathogenic M. smegmatis were grown in complete Middle Brook 7H9 broth. For some experiments, mycobacteria were heat-killed (80°C; 20 min). The supernatants of cultured PMs, having ingested mycobacteria for 6 h, 24 h, 4 days and 7 days, were harvested for the quantification of IL-1, IL-6, IL-10, IL-12 p40 and IL-12 p70 by using a multiplex suspension cytokine array system. Results The PMs infected with heat-killed mycobacteria, as compared to their respective live counterparts, invariably elaborated significantly (p

To eliminate an unwarranted metabolic pathway of the quinoline ring, a set of two compounds, where C-2 position of the antimalarial drug primaquine is blocked by metabolically stable bulky alkyl group are synthesized. Compound 2 [R = C(CH(3))(3)] of the series has produced excellent antimalarial efficacy against P. berghei and highly virulent multidrug-resistant P. yoelii nigeriensis strain in vivo. Compound 2 was also evaluated for methemoglobin (MetHb) toxicity. This study describes the discovery of a highly potent blood-schizontocidal antimalarial analogue 2, completely devoid of MetHb toxicity.

The effect of morphine on immunomodulation and host defense have been investigated during Plasmodiumbergheiinfection in BALB/c mice. A single low (5.0 mg/kg) subcutaneous dose of morphine strongly suppressed (sometimes completely eliminated) the parasitaemia, whereas a high dose (80.0 mg/kg) exerted mild potentiating effect. Mice treated with the low dose showed a significant (p < 0.05) increase in the total number of circulating leukocytes, the number (pool-size) of peritoneal macrophages, and the phagocytic activity of peritoneal macrophages, invitro. Conversely, in mice treated with the high dose, all these parameters were diminished. Silica (3.0 mg/mouse), administered intravenously, abrogated the morphine-induced protective effects but did not affect its potentiation of the infection. Naloxone pretreatment (4.0 mg/kg) completely blocked the protective effects of morphine, suggesting the mediation via naloxone-sensitive opiate-receptors; paradoxically, it did not affect the potentiating effects. These observations indicate that morphine exerted a dose-dependent, biphasic effect on the course of P.bergheiinfection in mice, apparently by modulating the macrophage-mediated protective mechanisms.

In continuing our search of potent antimalarials based on 8-aminoquinoline structural framework, three series of novel bis(8-aminoquinolines) using convenient one to four steps synthetic procedures were synthesized. The bisquinolines were evaluated for in vitro antimalarial (Plasmodium falciparum), antileishmanial (Leishmania donovani), antimicrobial (a panel of pathogenic bacteria and fungi), cytotoxicity, β-hematin inhibitory and methemoglobin (MetHb) formation activities. Several compounds exhibited superior antimalarial activities compared to parent drug primaquine. Selected compounds (44, 61 and 79) when tested for in vivo blood-schizontocidal antimalarial activity (Plasmodium berghei) displayed potent blood-schizontocial activities. The bisquinolines showed negligible MetHb formation (0.2–1.2%) underlining their potential in the treatment of glucose-6-phosphate dehydrogenase deficient patients. The bisquinoline analogues (36, 73 and 79) also exhibited promising in vitro antileishmanial activity, and antimicrobial activities (43, 44 and 76) against a panel of pathogenic bacteria and fungi. The results of this study provide evidence that bis(8-aminoquinolines), like their bis(4-aminoquinolines) and artemisinin dimers counterparts, are a promising class of antimalarial agents.

We report in vitro antimalarial activities against chloroquine sensitive and resistant Plasmodium falciparum strains, and in vivo activities against Plasmodium berghei in mice for four series of ring-substituted- l -histidines and histamines.

New primaquine conjugates 5-7 with glucosamine and two polymers of polyaspartamide type, poly/a,b-(N-2-hydroxyethyl-DL-aspartamide)/ (PHEA) and poly/a,b-(N-3-hydroxypropyl-DL-aspartamide)/ (PHPA), were synthesized, characterized and screened for their antimalarial activity. The conjugates differed in type of covalent bounding, length of spacer between the polymeric carrier and drug, molecular mass and drug-loading. Blood-schizontocidal activity of the prepared conjugates was tested against Plasmodium berghei infection in Swiss mice. The polymeric conjugates showed better antimalarial activity than glucosamine conjugate. U radu je opisana sinteza, karakterizacija i ispitivanje antimalarijskog djelovanja novih konjugata primakina 5-7 s glukozaminom i dva polimera poliaspartamidnog tipa, poli/a,b-(N-2-hidroksietil-DL-aspartamidom)/ (PHEA) i poli/a,b-(N-3-hidroksipropil-DL-aspartamidom)/ (PHPA). Konjugati su se razlikovali u vrsti kovalentne veze, duljini razmaknice između polimernog nosača i ljekovite tvari, molekulskoj masi i količini vezanog lijeka. Šizontocidno djelovanje pripravljenih konjugata ispitano je na miševima inficiranim Plasmodium berghei. Polimerni konjugati pokazali su jače antimalarijsko djelovanje nego konjugat s glukozaminom

The immunomodulatory effects of opioids are known in various infections. However, little is known about the effects of opioids in tuberculosis (TB). In the present study, we report the effects of morphine in Mycobacterium smegmatis infection in mice and macrophages. Morphine exerted a dose-dependent suppression of infection in vivo: 50 and 100 mg/kg morphine exerted significant (P

The effects of opiates in various infections are well known; however, very little is known about tuberculosis infection. Therefore, in the present study, we report for the first time, the effects of morphine during murine tuberculosis. Mice were infected intravenously with Mycobacterium tuberculosis H37Rv, administered morphine (0.1-100 mg/kg subcutaneously on day 0 and day +15) and sacrificed on day +30 for CFU enumeration in lungs and spleen. Morphine exerted maximum suppression of infection at 5 mg/kg, and sometimes completes elimination of infection; naloxone, silica and aminoguanidine blocked the protective effect of morphine. In vitro, morphine lacked direct antimycobacterial activity up to 1x10(-4) M concentration, as assessed by radiometric BACTEC method. In macrophage model of infection, morphine showed maximal killing at 1x10(-7) M concentration, the activity was blocked by naloxone and aminoguanidine. These observations suggest that morphine exerts a dose-dependent effect in murine tuberculosis, the protective effect being naloxone-reversible and may involve macrophage-mediated protective mechanisms. These results may be helpful in developing new opioid-like chemical entities against tuberculosis infection.

Serum amyloid P-component (SAP) plays important roles in host defense during various infectious diseases; however, nothing is known in tuberculosis (TB).To study the SAP response of Mycobacterium tuberculosis H37Rv- and H37Ra-infected mice, and to determine the effect(s) of purified mouse SAP both on their intra-alveolar macrophage (AM) uptake and intra-AM growth in vitro.The SAP levels of mice intratracheally infected with M. tuberculosis H37Rv and H37Ra were determined by ELISA. Mycobacterial AM uptake and intra-AM growth in vitro were determined using fluorescence microscopy and plating, respectively.M. tuberculosis H37Rv-infected mice showed significantly (p0.05) increased SAP levels (352.8+/-36.1 microg/ml) with compared mice infected with M. tuberculosis H37Ra (170+/-18.5 microg/ml). During the acute phase of both these infections, enhanced SAP levels correlated with the lung mycobacterial load. In vitro, purified mouse SAP (1-80 microg/ml) inhibited the AM uptake of both the mycobacteria in a concentration-dependent manners to a similar extent; 20 microg/ml SAP appeared optimal. Mycobacterial uptake inhibition was divalent cation- and pH-dependent, and was unaffected both by heat-inactivated and deglycosylated SAP, separately. Curiously, purified mouse SAP (1-80 microg/ml), in a concentration-dependent manner, inhibited the intra-AM growth of both M. tuberculosis H37Rv and H37Ra in vitro; the effect was 0.8 log10 CFUs greater on the latter. Both the mannose-based simple sugars and rabbit anti-mouse SAP polyclonal antibody, separately, annulled the inhibition of mycobacterial growth in vitro.This initial study demonstrates that both the SAP response of M. tuberculosis-infected mice, and the SAP-induced intra-AM mycobacterial growth inhibition in vitro were apparently dependent on mycobacterial virulence.

In the present communication, newly synthesized 8-quinolinamines (25-27) related to previously reported 2-tert-butylprimaquine (2) were evaluated for their in vitro antimalarial activity against chloroquine sensitive and resistant Plasmodium falciparum strains, in vivo antimalarial activity against P. berghei infected mice, in vitro antileishmanial activity against Leishmania donovani, in vitro antimicrobial activity against various fungi and bacteria, and cytotoxicity in a panel of mammalian cell lines. No promising cytotoxicities were observed for compounds reported herein. Analogue 25 was found to exhibit curative antimalarial activity at a dose of 25 mg/kg/dayx4 in a P. berghei infected mice model, and produced suppressive activity at a lower dose of 10 mg/kg/dayx4. In vitro antileishmanial activities (IC50 and IC90) comparable to standard drug pentamidine were exhibited by all synthesized 8-quinolinamines 25-27. At the same time, promising antibacterial and antifungal activities were also observed for synthesized compounds against a panel consisting of several bacteria and fungi.

Additional structural modifications of the new chemical entity, 2,8-dicyclopentyl-4-methylquinoline (DCMQ; MIC = 6.25 μg/mL, M. tuberculosis H37Rv ) resulted in the synthesis of four new series of the ring-substituted quinolinecarbohydrazides (series 1–4) constituting 22 analogues. All new derivatives were evaluated for in vitro antimycobacterial activities against drug-sensitive M. tuberculosis H37Rv strain. Certain ring-substituted-2-quinolinecarbohydrazide analogues described herein showed good inhibitory activity. In particular, analogues 4-(1-adamantyl)-2-quinolinecarbohydrazide ( 2d ), 4,5-dicyclopentyl-2-quinolinecarbohydrazide ( 2e ), 4,8-dicyclopentyl-2-quinolinecarbohydrazide ( 2f ), and 4,5-dicyclohexyl-2-quinolinecarbohydrazide ( 2g ) have exhibited the MIC value of 6.25 μg/mL. Further investigation of the most suitable lead prototype, 4-(1-adamantyl)-2-quinolinecarbohydrazide ( 2d , series 1) led to the synthesis of N2-alkyl/N2,N2-dialkyl/N2-aryl-4-(1-adamantyl)-2-quinolinecarboxamides (series 5) consisting of 13 analogues. Some of the synthesized carboxamides 7a , 7h , and 7m reported herein have exhibited excellent antimycobacterial activities in the range of 6.25–3.125 μg/mL against drug-sensitive and drug-resistant M. tuberculosis H37Rv strains.

The neuroimmunomodulatory effects of opiates during microbial infections are now well known; however, not much is known during leishmaniasis. Here, we report the effects of morphine on purified approximately 12-kDa component of Leishmania donovani amastigote antigen (LDAA-12)-induced colony-stimulating factor (CSF) production by mouse peritoneal macrophages (PMs) in vitro. Low concentrations (1 x 10(-9) and 1 x 10(-11) M) of morphine significantly (P0.05) augmented the production of CSFs, whereas high concentrations (1 x 10(-3) and 1 x 10(-5) M) inhibited CSF production. Morphine exerted a similar concentration-dependent biphasic effect on the LDAA-12-induced elaboration of granulocyte (G)-macrophage (M)-CSF (GM-CSF) and M-CSF by PMs in their conditioned medium, as quantified by using enzyme-linked immunosorbent assay. Furthermore, selective agonists of mu-(DAGO) and delta-(DPDPE) opioid receptors also, respectively, augmented and inhibited the production of CSFs. Pretreatment of PMs with naloxone (1 x 10(-5) M) significantly (P0.05) blocked the augmenting effect of morphine. In contrast, at 1 x 10(-5) M, naloxone lacked any effect on the inhibitory effect of morphine; however, its 100-fold higher concentration partially blocked it. This study, apparently for the first time, demonstrates that morphine, via surface opioid receptors, biphasically modulates the LDAA-12-induced CSF production by PMs, in vitro. These results thus show the implications of opiate abuse on the outcome of therapeutic interventions in areas where both visceral leishmaniasis and drug abuse are rampant.

Structural optimization of recently discovered new chemical entity, 2,8-dicyclopentyl-4-methylquinoline (DCMQ; MIC= 6.25 microg/mL, M. tuberculosis H37Rv) resulted in the synthesis of four new series of ring-substituted quinolinecarboxylic acids/esters constituting 45 analogues. All new derivatives were evaluated for in vitro antimycobacterial activities against M. tuberculosis H37Rv. Certain ring-substituted-2-quinolinecarboxylic acid ester and ring-substituted-2-quinoline acetic acid ester analogues described herein showed moderate to good inhibitory activity. In particular, three analogues methyl 4,5-dicyclopentyl-2-quinolinecarboxylate (3b), methyl 4,8-dicyclopentyl-2-quinolinecarboxylate (3c) and ethyl 2-(2,8-dicyclopentyl-4-quinolyl)acetate (14g) exhibited excellent MIC values of 1.00, 2.00 and 4.00microg/mL, respectively. Results obtained indicate that substitution of the quinoline ring with dicyclopentyl substituent presumably enhances the antimycobacterial activities in the quinoline analogues described herein.

We report in vitro antimycobacterial properties of ring-substituted quinolines (series 1-4) constituting 56 analogues against drug-sensitive and drug-resistant M. tuberculosis H37Rv strains. The most effective compounds 2h (R1 = R2 = c-C6H11, R3 = NO2, series 1) and 13g (R1 = OC7H15, R2 = NO2, series 4) have exhibited an MIC value of 1 microg/mL against drug-sensitive M. tuberculosis H37Rv strain that is comparable to first line anti-tuberculosis drug, isoniazid. Selected analogues (2d, 2g, 2h, 4e, 6b, 13b, 13g, and 14e, MIC:or = 6.25 microg/mL) upon further evaluation against single-drug-resistant (SDR) strains of M. tuberculosis H37Rv have produced potent efficacy in the range between 6.25 and 50 microg/mL.

Swiss mice vaccinated with Plasmodium yoelii nigeriensis-soluble antigen and saponin, following a homologous 100% lethal challenge, showed 60% protection (6 out of 10 mice survived). Monoclonal antibodies (MAbs), generated by hybridizing the Sp2/0 myeloma cells with the splenocytes of each of these ten mice, separately, were screened using enzyme-linked immunosorbent assay (ELISA), and were characterized by using merozoite (Mz) invasion inhibition assay in vitro, immunofluorescence assay (IFA), passive transfer of protection and ELISA-based isotyping. Curiously, purified MAbs from each of the six protected mice showed a distinct dichotomy: only two or three of them inhibited86% Mz invasion, whereas the remaining six to nine showed58% Mz invasion inhibition. However, none of the purified MAbs from the nonprotected mice could inhibit58% Mz invasion. Furthermore, the ability of the MAbs to inhibit Mz invasion appeared to correlate with their IFA-reactivity with the free-Mz, suggesting that these MAbs were directed against the Mz surface antigens involved in invasion. In passive transfer of protection experiments, pooled purified MAbs from protected mice, that inhibited86% Mz invasion, transferred 60% protection from challenge; the remaining pooled purified MAbs from protected mice, and those from nonprotected mice, when transferred separately, imparted only 30 and 10% protection, respectively. Isotypically, the MAbs belonged to IgG(1), IgG(2a), IgG(2b), and IgG(3) subclasses. Our results indicate that purified MAbs against P. yoelii nigeriensis, produced from the hybrids generated using the splenocytes of vaccinated and protected mice, belonged to two distinct groups: a small group that inhibited86% Mz invasion, strongly cross-reacted with free-Mz, transferred up to 60% passive protection, and belonged to IgG(2a) and IgG(3) subclasses, whereas the other relatively larger group inhibited58% Mz invasion, weakly cross-reacted with free-Mz, and transferred only 30% passive protection.

Morphine abuse is known to cause immunosuppression and enhanced host susceptibility to malaria. We studied the effect of morphine on the Plasmodium berghei total-parasite-antigens soluble in culture medium (P.b.SA)-induced production of colony-stimulating factors (CSFs) by mouse peritoneal macrophages, in vitro. Morphine exerted a concentration-dependent biphasic modulatory effect; at 1 x 10(-4)-1 x 10 x 10(-6) M it slightly inhibited, whereas at 1 X 10(-8)-1 x 10(-10) M it augmented the production of CSFs. However, at 1 x 10(-12) M concentration the augmenting effect of morphine was significantly (p0.05) diminished. Selective agonists of delta- (DPDPE) and mu- (DAGO) opioid receptors also respectively, inhibited and augmented the production of CSFs. The CSFs appear to be synthesized de novo as cycloheximide (50.0 microg/ml) completely inhibited their production. Naloxone ( 1 x 10(-5) M) lacked any effect on the inhibitory effect of morphine; however, at 1 x 10(-3) M it exerted partial blocking effect. Conversely, at 1 x 10(-5) M naloxone significantly (p0.05) blocked the augmenting effect of morphine. These results suggest that morphine via opioid receptors, in a concentration-dependent biphasic manner, modulated the P.b.SA-induced de novo production of CSFs by macrophages, in vitro.

An estimated 300-500 million new infections and 1.5-2.7 million deaths attributed to malaria occur annually in the developing world, and every year tens of millions of travelers from countries where malaria is not transmitted visit countries with malaria. Because the parasites that cause malaria have developed resistance to many antimalarial drugs, new methods for prevention are required. Intraperitoneal injection into mice of one dose of 150 ng (approximately 7.5 micrograms per kg body weight) recombinant mouse interleukin-12 (rmIL-12) 2 days before challenge with Plasmodium yoelii sporozoites protects 100% of mice against malaria. We report that one subcutaneous injection of 10 micrograms/kg recombinant human IL-12 (rhIL-12) 2 days before challenge with P. cynomolgi sporozoites protected seven of seven rhesus monkeys. Protection was associated with marked increases in plasma levels of interferon-gamma (IFN-gamma), and relative increases of lymphoid cell messenger RNA coding for IFN-gamma and several other cytokines. We speculate that rIL-12 protects monkeys through IFN-gamma-dependent elimination of P. cynomolgi-infected hepatocytes. This first report of rIL-12-induced protection of primates against an infectious agent supports assessment of rhIL-12 for immunoprophylaxis of human malaria.

Plasmodium cynomolgi total antigens soluble in culture medium (P.c.SA), and noninfective P. cynomolgi-infected monkey erythrocytes (P.c.IE) were compared for their potential to induce colony-stimulating factors (CSFs). When injected intravenously in monkeys, both preparations induced an increase in the serum CSFs levels; P.c.IE appeared to be 1.6-fold more potent than the P.c.SA. In vitro P.c.IE induced 1.8-fold more CSF by monkey blood monocyte-derived macrophages than P.c. However, both in vivo and in vitro, the peak CSFs levels induced by P.c.SA were attained apparently 8 h earlier. CSF generated by P.c.SA and P.c.IE induced the formation of macrophage, granulocyte and granulocyte-macrophage colonies, in vitro; P.c.IE-generated CSF induced the formation of significantly (P

The role of immune-complexes in the evasion of Plasmodium knowlesi from destruction by macrophages was studied in vitro. Incubation of macrophages with immune-complexes, prepared either by mixing total parasite antigens soluble in culture medium with normal or immune monkey serum, or by polyethylene glycol precipitation of serum from monkeys acutely infected with P. knowlesi, significantly reduced both the pool size of the macrophages that bound parasitized erythrocytes, and the number of parasitized erythrocytes bound per macrophage. Parasitized erythrocytes with mature schizonts were invariably preferred over those containing rings. These observations appear to indicate that during P. knowlesi infection in rhesus monkeys, immune-complexes may inhibit the binding of parasitized erythrocytes with mononuclear phagocytes and thus may enable them to evade the destructive mechanisms mounted by the host.