Prevalence of asymptomatic malaria infections in selected military camps in Tanzania

Background: Despite a decrease in malaria burden reported between 2000 and 2015, an increasing trend of malaria transmission has been recently reported in some endemic countries including Tanzania. Periodic monitoring to identify pocket areas for asymptomatic Plasmodium falciparum infection   is vital for malaria elimination efforts. The objective of this study was to determine prevalence of asymptomatic malaria infections among military recruits in selected camps in Tanzania. Methods: A cross-sectional study was conducted in 2015 at four military camps (Bulombora, Mgambo, Ruvu, and Rwamkoma) of National Service located in regions with varying malaria endemicity in Tanzania.  Finger prick blood samples collected from asymptomatic military recruits who had been at the camps for over two months were simultaneously tested using microscopy and malaria rapid diagnostic tests (mRDTs) to detect malaria parasite infections. Results: Malaria parasite prevalence among asymptomatic recruits was 20.3% and 19.4% by microscopy and mRDT respectively. There was moderate agreement (Kappa=0.724) between microscopy and mRDT test results. A significant difference (p<0.001) of malaria parasite prevalence among the four study camps was observed; ranging from 1.9% in Bulombora to 39.4% in Rwamkoma. The geometric mean parasite density was 11,053 asexual parasites/µl and most recruits (56.8%) had 200 to 1999 asexual parasites/µl. P. falciparum was the predominant (99.2%) malaria parasite species. Conclusion: Our study found high prevalence of asymptomatic malaria infections among military recruits in the selected camps, and this varied from one camp to another. The study has highlighted that public residence institutions such as military camps can be potential hotspots for malaria infection and therefore should not be skipped in routine national malaria surveillance system for monitoring trends of infection

Route map for the discovery and pre-clinical development of new drugs and treatments for cutaneous leishmaniasis.

Although there have been significant advances in the treatment of visceral leishmaniasis (VL) and several novel compounds are currently in pre-clinical and clinical development for this manifestation of leishmaniasis, there have been limited advances in drug research and development (R & D) for cutaneous leishmaniasis (CL). Here we review the need for new treatments for CL, describe in vitro and in vivo assays, models and approaches taken over the past decade to establish a pathway for the discovery, and pre-clinical development of new drugs for CL. These recent advances include novel mouse models of infection using bioluminescent Leishmania, the introduction of PK/PD approaches to skin infection, and defined pre-clinical candidate profiles

Novel benzoxaborole, nitroimidazole and aminopyrazoles with activity against experimental cutaneous leishmaniasis.

OBJECTIVES: Drugs for Neglected Diseases initiative (DNDi) has identified three chemical lead series, the nitroimidazoles, benzoxaboroles and aminopyrazoles, as innovative treatments for visceral leishmaniasis. The leads discovered using phenotypic screening, were optimised following disease- and compound-specific criteria. Several leads of each series were progressed and preclinical drug candidates have been nominated. Here we evaluate the efficacy of the lead compounds of each of these three chemical classes in in vitro and in vivo models of cutaneous leishmaniasis. METHODS: The in vitro activity of fifty-five compounds was evaluated against the intracellular amastigotes of L. major, L. aethiopica, L. amazonensis, L. panamensis, L. mexicana and L. tropica. The drugs demonstrating potent activity (EC50 < 5 μM) against at least 4 of 6 species were subsequently evaluated in vivo in different L. major - BALB/c mouse models using a 5 or 10-day treatment with either the oral or topical formulations. Efficacy was expressed as lesion size (measured daily using callipers), parasite load (by quantitative PCR - DNA) and bioluminescence signal reduction relative to the untreated controls. RESULTS: The selected drug compounds (3 nitroimidazoles, 1 benzoxaborole and 3 aminopyrazoles) showed consistent and potent activity across a range of Leishmania species that are known to cause CL with EC50 values ranging from 0.29 to 18.3 μM. In all cases, this potent in vitro antileishmanial activity translated into high levels of efficacy with a linear dose-response against murine CL. When administered at 50 mg/kg/day, DNDI-0690 (nitroimidazole), DNDI-1047 (aminopyrazole) and DNDI-6148 (benzoxaborole) all resulted in a significant lesion size reduction (no visible nodule) and an approximate 2-log-fold reduction of the parasite load as measured by qPCR compared to the untreated control. CONCLUSIONS: The lead compounds DNDI-0690, DNDI-1047 and DNDI-6148 showed excellent activity across a range of Leishmania species in vitro and against L. major in mice. These compounds offer novel potential drugs for the treatment of CL

Predicting the response to CTLA-4 blockade by longitudinal noninvasive monitoring of CD8 T cells

Immunotherapy using checkpoint-blocking antibodies against targets such as CTLA-4 and PD-1 can cure melanoma and non-small cell lung cancer in a subset of patients. The presence of CD8 T cells in the tumor correlates with improved survival. We show that immuno-positron emission tomography (immuno-PET) can visualize tumors by detecting infiltrating lymphocytes and, through longitudinal observation of individual animals, distinguish responding tumors from those that do not respond to therapy. We used 89 Zr-labeled PEGylated single-domain antibody fragments (VHHs) specific for CD8 to track the presence of intratumoral CD8 + T cells in the immunotherapy-susceptible B16 melanoma model in response to checkpoint blockade. A 89 Zr-labeled PEGylated anti-CD8 VHH detected thymus and secondary lymphoid structures as well as intratumoral CD8 T cells. Animals that responded to CTLA-4 therapy showed a homogeneous distribution of the anti-CD8 PET signal throughout the tumor, whereas more heterogeneous infiltration of CD8 T cells correlated with faster tumor growth and worse responses. To support the validity of these observations, we used two different transplantable breast cancer models, yielding results that conformed with predictions based on the antimelanoma response. It may thus be possible to use immuno-PET and monitor antitumor immune responses as a prognostic tool to predict patient responses to checkpoint therapies.National Institutes of Health (U.S.) (Grant R01-AI087879-06)National Institutes of Health (U.S.) (Grant DP1-GM106409-03)National Institutes of Health (U.S.) (Grant R01-GM100518-04)National Institutes of Health (U.S.) (Grant P01 CA080111

CELL WALL INVERTASE 4 is required for nectar production in Arabidopsis

To date, no genes have been reported to directly affect the de novo production of floral nectar. In an effort to identify genes involved in nectar production, the Affymetrix® ATH1 GeneChip was previously used to examine global gene expression profiles in Arabidopsis thaliana nectaries. One of the genes displaying highly enriched expression in nectaries was CELL WALL INVERTASE 4 (AtCWINV4, At2g36190), which encodes an enzyme that putatively catalyses the hydrolysis of sucrose into glucose and fructose. RT-PCR was used to confirm the nectary-enriched expression of AtCWINV4, as well as an orthologue from Brassica rapa. To probe biological function, two independent Arabidopsis cwinv4 T-DNA mutants were isolated. Unlike wild-type plants, cwinv4 lines did not produce nectar. While overall nectary morphology appeared to be normal, cwinv4 flowers accumulated higher than normal levels of starch in the receptacle, but not within the nectaries themselves. Conversely, wild-type, but not cwinv4, nectarial stomata stained intensely for starch. Cell wall extracts prepared from mutant flowers displayed greatly reduced invertase activity when compared with wild-type plants, and cwinv4 flowers also accumulated significantly lower levels of total soluble sugar. Cumulatively, these results implicate CWINV4 as an absolutely required factor for nectar production in the Brassicaceae, specifically by maintaining constant sink status within nectaries, thus allowing them to accumulate the sugars necessary for nectar production. In addition, CWINV4 is probably responsible for the hexose-rich composition observed for many Brassicaceae nectars

Cancer immunology and canine malignant melanoma: A comparative review

Oral canine malignant melanoma (CMM) is a spontaneously occurring aggressive tumour with relatively few medical treatment options, which provides a suitable model for the disease in humans. Historically, multiple immunotherapeutic strategies aimed at provoking both innate and adaptive anti-tumour immune responses have been published with varying levels of activity against CMM. Recently, a plasmid DNA vaccine expressing human tyrosinase has been licensed for the adjunct treatment of oral CMM. This article reviews the immunological similarities between CMM and the human counterpart; mechanisms by which tumours evade the immune system; reasons why melanoma is an attractive target for immunotherapy; the premise of whole cell, dendritic cell (DC), viral and DNA vaccination strategies alongside preliminary clinical results in dogs. Current “gold standard” treatments for advanced human malignant melanoma are evolving quickly with remarkable results being achieved following the introduction of immune checkpoint blockade and adoptively transferred cell therapies. The rapidly expanding field of cancer immunology and immunotherapeutics means that rational targeting of this disease in both species should enhance treatment outcomes in veterinary and human clinics

Mechanisms and in vivo functions of contact inhibition of locomotion

Contact inhibition of locomotion (CIL) is a process whereby a cell ceases motility or changes its trajectory upon collision with another cell. CIL was initially characterized more than half a century ago and became a widely studied model system to understand how cells migrate and dynamically interact. Although CIL fell from interest for several decades, the scientific community has recently rediscovered this process. We are now beginning to understand the precise steps of this complex behaviour and to elucidate its regulatory components, including receptors, polarity proteins and cytoskeletal elements. Furthermore, this process is no longer just in vitro phenomenology; we now know from several different in vivo models that CIL is essential for embryogenesis and in governing behaviours such as cell dispersion, boundary formation and collective cell migration. In addition, changes in CIL responses have been associated with other physiological processes, such as cancer cell dissemination during metastasis

Phenotypic and Genotypic Analysis of in vitro Selected Miltefosine Resistant Leishmania donovani

Abstract Visceral leishmaniasis is a devastating neglected parasitic disease caused by infection with Leishmania donovani. It life cycle has two stages with promastigote (insect stage) and amastigote (animal stage) morphologies. Miltefosine is currently the only commercially available oral drug available to treat leishmaniasis and recent evidence suggests clinical resistance has emerged. Due to the importance of this drug and the scarcity of new drugs in the pipeline, work has been done on understanding the mechanism(s) of miltefosine, yet the mechanism of action for resistance is still not known. In previous studies investigators generated miltefosine resistance on the insect vector stage (promastigotes), yet there is an important gap in understanding miltefosine resistance in the human infectious stage (amastigotes) of the disease. Before we could accomplish this goal a L. donovani cell line was converted into a stable, continuously cultured axenic amastigote cell line and characterized by disease burden generated in vitro and in vivo. The axenic line of L. donovani (MHOM/SD/75/1246/130) retains characteristics of amastigotes infecting macrophages and proliferated better than metacyclic promastigotes in macrophages in vitro and hamsters. The axenic amastigote line was used to induce miltefosine resistance by using discontinuous stepwise increasing drug pressure. Stable high-grade resistance was established (62-fold) and characterized in vitro and in vivo. Lastly, the fitness of miltefosine resistant versus susceptible parasite was established for the first time. This work adds the first efforts characterizing and understanding the complex problem of miltefosine resistance in amastigotes

Optimizing Function and Treatment of Hemodialysis Grafts and Fistulae

We are entering a new era for the management of hemodialysis grafts and fistulae. The hallmark of this new era will be the use of quantitative, hemodynamic parameters to optimize vascular access function and improve the results of our endovascular interventions. The implementation of vascular access surveillance programs has not only decreased the incidence of vascular access thrombosis, but also has provided new insights into the hemodynamic performance of grafts and fistulae. The measurement and analysis of intra-access blood flow has proven useful for the early detection of developing stenosis, and also provides a quantitative method to assess the results of our endovascular interventions. In the future, the use of quantitative hemodynamic measurements will play an increasingly important role in our evaluation and treatment of hemodialysis grafts and fistulae