ABSTRACT
Violence, abuse and neglect constitute major threats to children's health and wellbeing globally. However, until recently, relatively little systematic attention has been paid to the role of faith communities in shaping the protective environment for children. This paper describes the development of a measure to capture child-protective disposition amongst faith communities through field studies with faith leaders and their spouses in Senegal, Uganda and Guatemala. Identifying common factors related to child care and protection practices, orientation to child rights and approaches to discipline, the measure potentially serves to both inform and evaluate interventions seeking to engage with the beliefs and behaviours of faith communities to support children's health and wellbeing.
Subject(s)
Child Abuse , Spouses , Humans , Child , Uganda , Guatemala , Senegal , Child Abuse/prevention & controlABSTRACT
AIMS: Research into the relationship between pathogens, faecal indicator microbes and environmental factors in beach sand has been limited, yet vital to the understanding of the microbial relationship between sand and the water column and to the improvement of criteria for better human health protection at beaches. The objectives of this study were to evaluate the presence and distribution of pathogens in various zones of beach sand (subtidal, intertidal and supratidal) and to assess their relationship with environmental parameters and indicator microbes at a non-point source subtropical marine beach. METHODS AND RESULTS: In this exploratory study in subtropical Miami (Florida, USA), beach sand samples were collected and analysed over the course of 6 days for several pathogens, microbial source tracking markers and indicator microbes. An inverse correlation between moisture content and most indicator microbes was found. Significant associations were identified between some indicator microbes and pathogens (such as nematode larvae and yeasts in the genus Candida), which are from classes of microbes that are rarely evaluated in the context of recreational beach use. CONCLUSIONS: Results indicate that indicator microbes may predict the presence of some of the pathogens, in particular helminthes, yeasts and the bacterial pathogen Staphylococcus aureus including methicillin-resistant forms. Indicator microbes may thus be useful for monitoring beach sand and water quality at non-point source beaches. SIGNIFICANCE AND IMPACT OF THE STUDY: The presence of both indicator microbes and pathogens in beach sand provides one possible explanation for human health effects reported at non-point sources beaches.
Subject(s)
Bacteria/isolation & purification , Bathing Beaches , Environmental Monitoring/methods , Helminths/isolation & purification , Water Microbiology , Yeasts/isolation & purification , Animals , Colony Count, Microbial , Florida , Seawater/microbiology , Seawater/parasitology , Silicon Dioxide/analysisABSTRACT
The responses of pig aortic endothelial cells to sublethal doses of potentially toxic stimuli were investigated by monitoring K+ efflux, prostaglandin production, and the release of cytoplasmic purines. Xanthine plus xanthine oxidase reversibly stimulated these three parameters of endothelial cell function at doses that were not cytotoxic, as measured by chromium release, adenine uptake, and vital dye exclusion. The effects of xanthine plus xanthine oxidase were inhibited by catalase but not by superoxide dismutase, suggesting that H2O2 was responsible. Reagent H2O2 also reversibly stimulated K+ efflux, prostaglandin production, and the release of purines. The threshold concentration of H2O2 for these effects was approximately 10 microM, which was at least 30-fold lower than that which caused cytotoxicity. In addition to the direct effect of H2O2 in stimulating prostaglandin production (PGI2 and PGE2), prior exposure of endothelial cells to lower doses of H2O2 (less than 0.1 microM) at high oxygen tension inhibited the subsequent stimulation of prostaglandin production by ATP, A23187, and H2O2 itself. We conclude that H2O2 has substantial effects on endothelial physiology at doses up to 3,000-fold lower than those which induce cytotoxicity.
Subject(s)
Aorta , Hydrogen Peroxide/toxicity , Animals , Endothelium/drug effects , Endothelium/metabolism , Endothelium/physiology , Epoprostenol/biosynthesis , Free Radicals , Microcirculation/physiology , Oxygen/metabolism , Purines/metabolism , Radioisotopes , Rubidium/metabolism , Swine , Xanthine Oxidase/toxicity , Xanthines/toxicityABSTRACT
Topical exposure of mice to chemical allergens results in the migration of epidermal Langerhans cells (LCs) from the skin and their accumulation as immunostimulatory dendritic cells (DCs) in draining lymph nodes. Epidermal cell-derived cytokines have been implicated in the maturation and migration of LCs, but the adhesion molecules that regulate LC migration have not been studied. We hypothesized that integrin-mediated interactions with extracellular matrix components of the skin and lymph node may regulate LC/DC migration. We found that alpha 6 integrins and alpha 4 integrins were differentially expressed by epidermal LCs and lymph node DCs. A majority of LCs (70%) expressed the alpha 6 integrin subunit, whereas DCs did not express alpha 6 integrins. In contrast, the alpha 4 integrin subunit was expressed at high levels on DCs but at much lower levels on LCs. The anti-alpha 6 integrin antibody, GoH3, which blocks binding to laminin, completely prevented the spontaneous migration of LCs from skin explants in vitro and the rapid migration of LCs from mouse ear skin induced after intradermal administration of TNF-alpha in vivo. GoH3 also reduced the accumulation of DCs in draining lymph nodes by a maximum of 70% after topical administration of the chemical allergen oxazolone. LCs remaining in the epidermis in the presence of GoH3 adopted a rounded morphology, rather than the interdigitating appearance typical of LCs in naive skin, suggesting that the cells had detached from neighboring keratinocytes and withdrawn cellular processes in preparation for migration, but were unable to leave the epidermis. The anti-alpha 4 integrin antibody PS/2, which blocks binding to fibronectin, had no effect on LC migration from the epidermis either in vitro or in vivo, or on the accumulation of DCs in draining lymph nodes after oxazolone application. RGD-containing peptides were also without effect on LC migration from skin explants. These results identify an important role for alpha 6 integrins in the migration of LC from the epidermis to the draining lymph node by regulating access across the epidermal basement membrane. In contrast, alpha 4 integrins, or other integrin-dependent interactions with fibronectin that are mediated by the RGD recognition sequence, did not influence LC migration from the epidermis. In addition, alpha 4 integrins did not affect the accumulation of LCs as DCs in draining lymph nodes.
Subject(s)
Antigens, CD/physiology , Cell Movement/immunology , Epidermis/immunology , Integrins/physiology , Langerhans Cells/immunology , Animals , Antibodies, Blocking/administration & dosage , Antibodies, Blocking/pharmacology , Antibodies, Monoclonal/pharmacology , Antigens, CD/biosynthesis , Antigens, CD/immunology , Cell Movement/drug effects , Dendritic Cells/metabolism , Epidermis/drug effects , Immunoglobulin G/administration & dosage , Integrin alpha4 , Integrin alpha6 , Integrins/biosynthesis , Langerhans Cells/drug effects , Langerhans Cells/metabolism , Mice , Mice, Inbred BALB C , Oligopeptides/pharmacology , Organ Culture Techniques , Rats , SkinABSTRACT
Lymphocyte migration from high endothelial venules into lymphoid organs is mediated by a sequence of interactions between cell adhesion molecules on lymphocytes and those on the vascular endothelial cells that line the vessels. recent studies suggest that the so-called lymphocyte homing receptors and vascular addressins regulate the first stages of this process, that of binding of lymphocytes from flowing blood. The subsequent crawling of lymphocytes over the endothelial cell surface and migration across the vessel wall (diapedesis) are regulated independently of initial binding. These latter stages are thought to be mediated by functional activation of integrins on the lymphocyte by chemoattractants located in the vessel wall.
ABSTRACT
The recruitment of leukocytes from the bloodstream is a key step in the inflammatory reaction, and chemokines are among the main regulators of this process. During lymphocyte-endothelial interaction, chemokines induce the polarization of T lymphocytes, with the formation of a cytoplasmic projection (uropod) and redistribution of several adhesion molecules (ICAM-1,-3, CD43, CD44) to this structure. Although it has been reported that these cytokines regulate the adhesive state of integrins in leukocytes, their precise mechanisms of chemoattraction remain to be elucidated. We have herein studied the functional role of the lymphocyte uropod. Confocal microscopy studies clearly showed that cell uropods project away from the cell bodies of adhered lymphocytes and that polarized T cells contact other T cells through the uropod structure. Time-lapse videomicroscopy studies revealed that uropod-bearing T cells were able, through this cellular projection, to contact, capture, and transport additional bystander T cells. Quantitative analysis revealed that the induction of uropods results in a 5-10-fold increase in cell recruitment. Uropod-mediated cell recruitment seems to have physiological relevance, since it was promoted by both CD45R0+ peripheral blood memory T cells as well as by in vivo activated lymphocytes. Additional studies showed that the cell recruitment mediated by uropods was abrogated with antibodies to ICAM-1, -3, and LFA-1, whereas mAb to CD43, CD44, CD45, and L-selectin did not have a significant effect, thus indicating that the interaction of LFA-1 with ICAM-1 and -3 appears to be responsible for this process. To determine whether the increment in cell recruitment mediated by uropod may affect the transendothelial migration of T cells, we carried out chemotaxis assays through confluent monolayers of endothelial cells specialized in lymphocyte extravasation. An enhancement of T cell migration was observed under conditions of uropod formation, and this increase was prevented by incubation with either blocking anti-ICAM-3 mAbs or drugs that impair uropod formation. These data indicate that the cell interactions mediated by cell uropods represent a cooperative mechanism in lymphocyte recruitment, which may act as an amplification system in the inflammatory response.
Subject(s)
Cell Adhesion Molecules/analysis , Chemokines/pharmacology , Chemotaxis, Leukocyte/immunology , Cytoplasm/immunology , T-Lymphocytes/cytology , Cell Adhesion Molecules/physiology , Cell Communication/immunology , Cell Membrane/chemistry , Cell Polarity , Cells, Cultured , Endothelium, Vascular/immunology , Humans , Immunologic Memory , Leukocyte Common Antigens/analysis , Lymphocyte Activation , T-Lymphocytes/immunologyABSTRACT
Resilience is increasingly recognised as a key process mitigating the impact of shocks and stressors on functioning. The literature on individual and community resilience is being extended to address characteristics of resilient service delivery systems in contexts of adversity. The validity and utility of a capacity-oriented resilience framework (including absorption, adaptation and transformation) is examined with respect to the functioning of United Nations Relief and Works Agency for Palestine Refugees in the Near East (UNRWA) health systems in Lebanon and Jordan in the context of the Syrian crisis. We completed 62 semi-structured interviews (30 in Lebanon in November-December 2016, and 32 in Jordan in January 2017) with professionals at primary care, area, and country management levels. Participants reflected on changes in population health status and health service delivery during the Syrian crisis, notably with respect to the influx of refugees from Syria. Interviews were analysed through inductive thematic analysis and used to critically interrogate health systems resilience against a pro-capacities framework. We find that UNRWA systems in Lebanon and Jordan were broadly resilient, deploying diverse strategies to address health challenges and friction between host and refugee populations. Absorptive capacity was evidenced by successful accommodation of increased patient numbers across most service areas. Adaptive capacities were reflected in broadening of collaboration and reconfiguration of staff roles to enhance service delivery. Transformative capacities were demonstrated in the revision of the service packages provided. While manifest as technical capacities, these clearly drew upon solidarity and commitment linked to the political context of the Palestinian experience. The study adds to the limited literature on health system and organizational resilience and indicates that capacity-oriented framings of resilience are valuable in extracting generalizable lessons for health systems facing adversity. The proposed resilience framework promises to guide strategies for sustained care delivery in these contexts.
Subject(s)
Arabs , Delivery of Health Care/organization & administration , Health Services Needs and Demand/organization & administration , Refugees , Resilience, Psychological , Government Programs/organization & administration , Humans , Interviews as Topic , Jordan , Lebanon , SyriaABSTRACT
The effects of neutrophil elastase on endothelial prostacyclin (PGI2) production, nucleotide release, and responsiveness to vasoactive agents were compared with the effects of cathepsin G (the other major neutral protease of neutrophils), pancreatic elastase, trypsin, chymotrypsin, and thrombin. PGI2 production by pig aortic endothelial cells cultured on microcarrier beads and perfused in columns was stimulated in a dose-dependent manner by trypsin, chymotrypsin, and cathepsin G (1-100 micrograms/ml for 3 min). Thrombin, while active at low concentrations (0.1-10 National Institutes of Health U/ml), induced smaller responses. Neutrophil and pancreatic elastase had little or no effect on PGI2 production. Dose-dependent, selective release of adenine nucleotides was induced by neutrophil elastase (3-30 micrograms/ml). The other proteases were much less active; for example, trypsin (100 micrograms/ml) induced a response only approximately 5% as great as did 30 micrograms/ml neutrophil elastase. After exposure to 30 micrograms/ml neutrophil elastase, cells did not exhibit the characteristic burst of PGI2 production in response to extracellular ATP; responsiveness gradually returned after 40-120 min. This effect was not seen with the other proteases. Elastase partly inhibited responses to bradykinin and had no effect on PGI2 production that was stimulated by ionophore A23187. There was no evidence of cytotoxicity, as measured by release of lactate dehydrogenase. Neutrophil degranulation can generate concentrations of elastase and cathepsin G comparable with those tested in the present study, and the effects of these enzymes on endothelial function lead us to suggest that they may play a role in vasoregulation and vascular pathology.
Subject(s)
Adenine Nucleotides/metabolism , Aorta, Thoracic/metabolism , Bradykinin/pharmacology , Calcimycin/pharmacology , Epoprostenol/biosynthesis , Neutrophils/enzymology , Pancreatic Elastase/blood , Pancreatic Elastase/pharmacology , Peptide Hydrolases/pharmacology , Adenosine Triphosphate/pharmacology , Animals , Cell Survival/drug effects , Cells, Cultured , Endothelium/cytology , Endothelium/drug effects , Endothelium/metabolism , Humans , L-Lactate Dehydrogenase/analysis , SwineABSTRACT
Infections caused by bacteria in the airway preferentially induce a Th17 response. However, the mechanisms involved in the regulation of CD4 T-cell responses in the lungs are incompletely understood. Here, we have investigated the mechanisms involved in the regulation of Th17 differentiation in the lungs in response to immunization with lipopolysaccharide (LPS) as an adjuvant. Our data show that both Myd88 and TRIF are necessary for Th17 induction. This distinctive fate determination can be accounted for by the pattern of inflammatory cytokines induced by airway administration of LPS. We identified the production of interleukin (IL)-1ß and IL-6 by small macrophages and IL-23 by alveolar dendritic cells (DCs), favoring Th17 responses, and IL-10 repressing interferon (IFN)-γ production. Furthermore, we show that exogenous IL-1ß can drastically alter Th1 responses driven by influenza and lymphocytic choriomeningitis virus infection models and induce IL-17 production. Thus, the precision of the lung immune responses to potential threats is orchestrated by the cytokine microenvironment, can be repolarized and targeted therapeutically by altering the cytokine milieu. These results indicate that how the development of Th17 responses in the lung is regulated by the cytokines produced by lung DCs and macrophages in response to intranasal immunization with LPS adjuvant.
Subject(s)
Adaptor Proteins, Vesicular Transport/metabolism , Influenza A Virus, H1N1 Subtype/immunology , Lung/metabolism , Lymphocytic Choriomeningitis/immunology , Lymphocytic choriomeningitis virus/immunology , Myeloid Differentiation Factor 88/metabolism , Orthomyxoviridae Infections/immunology , Th17 Cells/immunology , Adaptor Proteins, Vesicular Transport/genetics , Administration, Intranasal , Animals , Cell Differentiation , Cells, Cultured , Cellular Microenvironment , Cytokines/metabolism , Immunization , Lipopolysaccharides/immunology , Lung/pathology , Lymphocyte Activation , Mice , Mice, Inbred C57BL , Mice, Knockout , Myeloid Differentiation Factor 88/geneticsABSTRACT
Mental health is becoming a central issue for public health complex emergencies. In this review we present a culturally valid mental health action plan based on scientific evidence that is capable of addressing the mental health effects of complex emergencies. A mental health system of primary care providers, traditional healers, and relief workers, if properly trained and supported, can provide cost-effective, good mental health care. This plan emphasises the need for standardised approaches to the assessment, monitoring, and outcome of all related activities. Crucial to the improvement of outcomes during crises and the availability to future emergencies of lessons learned from earlier crises is the regular dissemination of the results achieved with the action plan. A research agenda is included that should, in time, fill knowledge gaps and reduce the negative mental health effects of complex emergencies.
Subject(s)
Disasters , Mental Health Services , Refugees , Warfare , Depression/etiology , Depression/therapy , Emergencies , Health Services Research , Humans , Mental Health Services/organization & administration , Refugees/psychology , Stress Disorders, Post-Traumatic/etiology , Stress Disorders, Post-Traumatic/therapyABSTRACT
Fc gammaRIIIb is a glycosylphosphatidylinositol(GPI)-anchored, low-affinity IgG receptor, expressed exclusively on human neutrophils. Upon activation or apoptosis of neutrophils, Fc gammaRIIIb is shed from the cell surface, but the enzyme(s) responsible for this process is (are) still unknown. Recently, metalloproteases have been suggested to mediate the shedding of cell surface proteins such as L-selectin and TNF-alpha. Using hydroxamic acid-based inhibitors of this class of proteases (BB-3103, Ro31-9790), we have observed a clear inhibitory effect on Fc gammaRIIIb shedding after PMA stimulation of neutrophils or induction of apoptosis. These inhibitors did not affect PMA-induced degranulation or superoxide generation.
Subject(s)
Metalloendopeptidases/metabolism , Neutrophils/immunology , Receptors, IgG/metabolism , Enzyme-Linked Immunosorbent Assay , Flow Cytometry , Humans , Hydroxamic Acids/pharmacology , L-Selectin/metabolism , Metalloendopeptidases/antagonists & inhibitors , Protease Inhibitors/pharmacology , Superoxides/metabolism , Tetradecanoylphorbol Acetate/antagonists & inhibitors , Tetradecanoylphorbol Acetate/pharmacologyABSTRACT
Feeding a vitamin E-deficient diet containing 5% menhaden oil to mice affords significant protection against both a chloroquine-sensitive and a chloroquine-resistant line of the malarial parasite. Nutritional manipulation may offer a new approach to the problem of drug-resistant malaria, a rapidly emerging global threat to public health.
Subject(s)
Diet , Fish Oils/therapeutic use , Malaria/prevention & control , Vitamin E Deficiency , Vitamin E/administration & dosage , Animals , Chloroquine/pharmacology , Drug Resistance , Fish Oils/administration & dosage , Male , Mice , Plasmodium falciparum/drug effectsABSTRACT
Young female mice were fed torula-yeast-based diets deficient in vitamin E or selenium or supplemented with cod-liver oil to determine the effect of host antioxidant status on the therapeutic efficacy of the Chinese traditional antimalarial drug qinghaosu (QHS), a sesquiterpene endoperoxide. Vitamin E deficiency enhanced the antimalarial action of QHS against Plasmodium yoelii, both in terms of decreased parasitemia and improved survival but Se deficiency did not. A vitamin E-deficient diet containing 5% cod-liver oil had such strong antimalarial activity in itself that no additional therapeutic benefit of QHS could be demonstrated. Hematocrit values in parasitized mice treated with QHS or fed the cod-liver-oil-supplemented, vitamin E-deficient diet were normal. Nutritional manipulation of host antioxidant status may provide a promising prophylactic and/or therapeutic tool for the control of malaria.
Subject(s)
Antimalarials/pharmacology , Artemisinins , Drugs, Chinese Herbal/pharmacology , Plasmodium yoelii/drug effects , Sesquiterpenes/pharmacology , Vitamin E Deficiency/metabolism , Animals , Antioxidants , Cod Liver Oil/pharmacology , Disease Susceptibility , Female , Malaria/complications , Malaria/parasitology , Mice , Plasmodium yoelii/pathogenicity , Selenium/deficiency , Vitamin E Deficiency/complicationsABSTRACT
A two-step reaction sequence between artemisinin and methanolic ammonia followed by treatment with Amberlyst 15 yielded 11-azaartemisinin in 65% yield. Substituting a variety of primary alkyl- and heteroaromatic amines for ammonia in the reaction sequence yields N-substituted 11-azaartemisinins in similar or greater yield. When Amberlyst 15 is replaced by a mixture of sulfuric acid/silica gel, both 11-azaartemisinin and the expected metabolite, 10-azadesoxyartemisinin, are formed in 45% and 15% yields, respectively. In vitro and in vivo test data for a number of novel N-substituted 11-azaartemisinins, against drug-resistant strains of Plasmodium falciparum, show they possess antimalarial activities equal to or greater than that of artemisinin. The most active derivative, N-(2'-acetaldehydo)-11-azaartemisinin, 17, was 26 times more active in vitro and 4 times more active in vivo than artemisinin.
Subject(s)
Antimalarials/pharmacology , Artemisinins , Plasmodium berghei/drug effects , Plasmodium falciparum/drug effects , Sesquiterpenes/pharmacology , Animals , Antimalarials/chemical synthesis , Antimalarials/chemistry , Drug Evaluation, Preclinical , Drugs, Chinese Herbal/pharmacology , Magnetic Resonance Spectroscopy , Malaria/drug therapy , Malaria/parasitology , Mass Spectrometry , Mice , Molecular Structure , Sesquiterpenes/chemical synthesis , Sesquiterpenes/chemistry , Structure-Activity RelationshipABSTRACT
Dispiro-1,2,4,5-tetraoxanes 2-4 were synthesized as potential peroxide antimalarial drugs. They had curative activity against Plasmodium berghei in vivo at single doses of 320 and 640 mg/kg which confirms earlier unpublished data. Moreover, artemisinin (1) and 4 had equivalent ED50's against P. berghei in vivo in the multiple-dose Thompson test; neither showed any evidence of acute toxicity at total doses of more than 12 g/kg. Dispiro-1,2,4,5-tetraoxane 4 had IC50's comparable to those of 1 against Plasmodium falciparum clones in vitro. These results confirm the potential of dispiro-1,2,4,5-tetraoxanes as a new class of inexpensive peroxide antimalarial drugs.
Subject(s)
Antimalarials/pharmacology , Ethylene Oxide/pharmacology , Peroxides/pharmacology , Spiro Compounds/pharmacology , Animals , Antimalarials/chemistry , Ethylene Oxide/analogs & derivatives , Ethylene Oxide/chemistry , Male , Mice , Molecular Structure , Peroxides/chemistry , Plasmodium berghei/drug effects , Plasmodium falciparum/drug effects , Spiro Compounds/chemistryABSTRACT
On the basis of observations that several bisquinolines such as piperaquine possess notable activity against chloroquine-resistant malaria, 13 N,N-bis-(7-chloroquinolin-4-yl)alkanediamines were synthesized and screened against Plasmodium falciparum in vitro and Plasmodium berghei in vivo. Twelve of the thirteen bisquinolines had a significantly lower resistance index than did chloroquine; the resistance index was apparently unrelated to either in vitro or in vivo activity. Except for two compounds, there was a reasonable correlation between in vitro and in vivo activities. Seven of the thirteen bisquinolines had IC50's of less than 6 nM against both chloroquine-sensitive (D-6) and -resistant (W-2) clones of P. falciparum and were curative against P. berghei at doses of 640 mg/kg. In contrast to chloroquine, these bisquinolines did not show any toxic deaths at curative dose levels. Four bisquinolines, however, caused skin lesions at the site of injection. Maximum activity was seen in bisquinolines with a connecting bridge of two carbon atoms where decreased conformational mobility seemed to increase activity. Bisquinoline 3 (+/-)-trans-N1,N2-bis(7-chloroquinolin-4-yl)cyclohexane-1,2-diamin e was not only the most potent bisquinoline in vitro, but was clearly unique in its in vivo activity--80% and 100% cure rates were achieved at doses of 160 and 320 mg/kg, respectively. In summary, these preliminary results support the premise that bisquinolines may be useful agents against chloroquine-resistant malaria.
Subject(s)
Antimalarials/chemical synthesis , Cyclohexylamines/chemical synthesis , Malaria/drug therapy , Quinolines/chemical synthesis , Animals , Antimalarials/pharmacology , Antimalarials/therapeutic use , Chloroquine/therapeutic use , Cyclohexylamines/pharmacology , Cyclohexylamines/therapeutic use , Drug Resistance , Molecular Conformation , Molecular Structure , Plasmodium berghei/drug effects , Plasmodium falciparum/drug effects , Quinolines/pharmacology , Quinolines/therapeutic use , Structure-Activity RelationshipABSTRACT
N,N-Bis(7-chloroquinolin-4-yl)heteroalkanediamines 1-11 were synthesized and screened against Plasmodium falciparum in vitro and Plasmodium berghei in vivo. These bisquinolines had IC50 values from 1 to 100 nM against P. falciparum in vitro. Six of the 11 bisquinolines were significantly more potent against the chloroquine-resistant W2 clone compared to the chloroquine-sensitive D6 clone. For bisquinolines 1-11 there was no relationship between the length of the bisquinoline heteroalkane bridge and antimalarial activity and no correlation between in vitro and in vivo antimalarial activities. Bisquinolines with alkyl ether and piperazine bridges were substantially more effective than bisquinolines with alkylamine bridges against P. berghei in vivo. Bisquinolines 1-10 were potent inhibitors of hematin polymerization with IC50 values falling in the narrow range of 5-20 microM, and there was a correlation between potency of inhibition of hematin polymerization and inhibition of parasite growth. Compared to alkane-bridged bisquinolines (Vennerstrom et al., 1992), none of these heteroalkane-bridged bisquinolines had sufficient antimalarial activity to warrant further investigation of the series.
Subject(s)
Antimalarials/chemical synthesis , Quinolines/chemical synthesis , Animals , Antimalarials/chemistry , Antimalarials/pharmacology , Biopolymers , Hemin/metabolism , Malaria/drug therapy , Male , Mice , Plasmodium berghei , Plasmodium falciparum/drug effects , Quinolines/chemistry , Quinolines/pharmacology , Structure-Activity RelationshipABSTRACT
A series of quaternary 2-phenylimidazo[1,2-a]pyridinum salts has been prepared and evaluated for antiparasitic activity. Primary attention was focused on derivatives with amido, substituted hydrazone, and heterocyclic functionality at the para position of the phenyl substituent. Guanylhydrazones and N-substituted guanylhydrazones of the 4'-formyl-substituted compounds are very active against the blood state Trypanosoma rhodesiense in mice by subcutaneous or oral administration. The most potent compounds attain 100% survival for 30 days at doses of less than 1.0 mg/kg (sc) and greater than 5.0 mg/kg (po). Weaker activity is noted for certain other 4'-substituents such as carboxamidines and carboxamide oximes. Considerable variation in structure, including replacing of the imidazo [1,2-a]pyridinium ring by other cationic heterocyclic rings and insertion of linking groups between the heterocyclic ring and phenyl group, can be done, and a high level of activity is maintained. Relationships between these structural changes and biological activity are discussed.
Subject(s)
Guanosine/analogs & derivatives , Hydrazones/therapeutic use , Imidazoles/therapeutic use , Pyridinium Compounds/therapeutic use , Trypanocidal Agents , Animals , Cations , Chemical Phenomena , Chemistry , Guanosine/chemical synthesis , Guanosine/pharmacology , Guanosine/therapeutic use , Hydrazones/chemical synthesis , Hydrazones/pharmacology , Imidazoles/chemical synthesis , Imidazoles/pharmacology , Leucine/metabolism , Molecular Structure , Pyridinium Compounds/chemical synthesis , Pyridinium Compounds/pharmacology , Structure-Activity Relationship , Thymidine/metabolism , Trypanosoma brucei brucei/drug effects , Trypanosoma brucei brucei/metabolism , Trypanosomiasis/drug therapyABSTRACT
A total of 34 analogues of the biguanide PS-15 (5s), a prodrug of the diaminotriazine WR-99210 (8s), have been prepared. Several of them, such as 5b (PS-33) and 5m (PS-26), maintain or exceed the in vivo activity of PS-15 while not requiring the use of highly regulated starting materials. The putative diaminotriazine metabolites of these new analogues (compounds 8) have also been prepared and shown to maintain the activity against resistant P. falciparum strains. The structure-activity relationships of biguanides 5 and putative metabolites 8 are discussed.
Subject(s)
Antimalarials/chemical synthesis , Folic Acid Antagonists/chemical synthesis , Guanidines/chemical synthesis , Prodrugs/chemical synthesis , Proguanil/analogs & derivatives , Proguanil/chemical synthesis , Tetrahydrofolate Dehydrogenase/metabolism , Triazines/chemical synthesis , Animals , Antimalarials/chemistry , Antimalarials/pharmacology , Antimalarials/toxicity , Drug Evaluation, Preclinical , Female , Folic Acid Antagonists/chemistry , Folic Acid Antagonists/pharmacology , Folic Acid Antagonists/toxicity , Guanidines/chemistry , Guanidines/pharmacology , Guanidines/toxicity , Malaria/drug therapy , Male , Mice , Plasmodium berghei , Plasmodium falciparum/drug effects , Prodrugs/chemistry , Prodrugs/pharmacology , Prodrugs/toxicity , Proguanil/chemistry , Proguanil/pharmacology , Proguanil/toxicity , Structure-Activity Relationship , Triazines/chemistry , Triazines/pharmacology , Triazines/toxicityABSTRACT
Sixteen alkyl-substituted dispiro-1,2,4,5-tetraoxanes (7,8,15, 16-tetraoxadispiro[5.2.5.2]hexadecanes) were synthesized to explore dispiro-1,2,4,5-tetraoxane SAR and to identify tetraoxanes with better oral antimalarial activity than prototype tetraoxane 1 (WR 148999). The tetraoxanes were prepared either by peroxidation of the corresponding cyclohexanone derivatives in H(2)SO(4)/CH(3)CN or by ozonolysis of the corresponding cyclohexanone methyl oximes. Those tetraoxanes with alkyl substituents at the 1 and 10 positions were formed as single stereoisomers, whereas the five tetraoxanes formed without the stereochemical control provided by alkyl groups at the 1 and 10 positions were isolated as mixtures of diastereomers. Three of the sixteen tetraoxanes were inactive (IC(50)'s > 1000 nM), but five (2, 6, 10, 11, 12) had IC(50)'s between 10 and 30 nM against the chloroquine-sensitive D6 and chloroquine-resistant W2 clones of Plasmodium falciparum compared to corresponding IC(50)'s of 55 and 32 nM for 1 and 8.4 and 7.3 nM for artemisinin. We suggest that tetraoxanes 13, 16, and 17 were inactive and tetraoxanes 4 and 7 were weakly active due to steric effects preventing or hindering peroxide bond access to parasite heme. Tetraoxanes 1, 10, 11, and 14, along with artemisinin and arteether as controls, were administered po b.i.d. (128 mg/kg/day) to P. berghei-infected mice on days 3, 4, and 5 post-infection. At this dose, tetraoxanes 10, 11, and 14 cured between 40% and 60% of the infected animals. In comparison, artemisinin and tetraoxane 1 produced no cures, whereas arteether cured 100% of the infected animals. There was no apparent relationship between tetraoxane structure and in vitro neurotoxicity, nor was there any correlation between antimalarial activity and neurotoxicity for these seventeen tetraoxanes.