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Leishmania parasites, the causative agents of leishmaniasis, are protozoan parasites with the ability to modify the signalling pathway and cell responses of their infected host cells. These parasite strategies alter the host cell environment and conditions favouring their replication, survival and pathogenesis. Since microRNAs (miRNAs) are able to post-transcriptionally regulate gene expression processes, these biomolecules can exert critical roles in controlling Leishmania-host cell interplay. Therefore, the identification of relevant miRNAs differentially expressed in Leishmania parasites as well as in infected cells, which affect the host fitness, could be critical to understand the infection biology, pathogenicity and immune response against these parasites. Accordingly, the current review aims to address the differentially expressed miRNAs in both, the parasite and infected host cells and how these biomolecules change cell signalling and host immune responses during infection. A deep understanding of these processes could provide novel guidelines and therapeutic strategies for managing and treating leishmaniasis. [ABSTRACT FROM AUTHOR]

Apolipoprotein A-I (apo A-I) represents the main component of the Trypanosomelytic factor (TLF) which contributes to the host innate immunity against Trypanosomaand Leishmania. These parasites use complex and multiple strategies such as molecular mimicry to evade or subvert the host immune system. Previous studies have highlighted the adaptation mechanisms of TLF-resistant Trypanosomaspecies. These data might support the hypothesis that Leishmaniaparasites (amastigote forms in macrophages) might express apo A-I to bypass and escape from TLF action as a component of the host innate immune responses. The anti-inflammatory property of apo A-I is another mechanism that supports our idea that apo A-I may play a role in Leishmaniaparasites allowing them to bypass the host innate immune system.

The association of leishmaniasis and malignancies in human and animal models has been highlighted in recent years. The misdiagnosis of coexistence of leishmaniasis and cancer and the use of common drugs in the treatment of such diseases prompt us to further survey the molecular biology of Leishmania parasites and cancer cells. The information regarding common expressed proteins, as possible therapeutic targets, in Leishmania parasites and cancer cells is scarce. Therefore, the current study reviews proteins, and investigates the regulation and functions of several key proteins in Leishmania parasites and cancer cells. The up- and down-regulations of such proteins were mostly related to survival, development, pathogenicity, metabolic pathways and vital signalling in Leishmania parasites and cancer cells. The presence of common expressed proteins in Leishmania parasites and cancer cells reveals valuable information regarding the possible shared mechanisms of pathogenicity and opportunities for therapeutic targeting in leishmaniasis and cancers in the future. [ABSTRACT FROM AUTHOR]

Plasmodium falciparum is the main cause of severe malaria in humans that can lead to death. There is growing evidence of drug-resistance in P. falciparum treatment, and the design of effective vaccines remains an ongoing strategy to control the disease. On the other hand, the recognition of specific diagnostic markers for P. falciparum can accelerate the diagnosis of this parasite in the early stages of infection. Therefore, the identification of novel antigenic proteins especially by proteomic tools is urgent for vaccination and diagnosis of P. falciparum. The proteome diversity of the life cycle stages of P. falciparum, the altered proteome of P. falciparum-infected human sera and altered proteins in P. falciparum-infected erythrocytes could be proposed as appropriate proteins for the aforementioned aims. Accordingly, this review highlights and proposes different proteins identified using proteomic approaches as promising markers in the diagnosis and vaccination of P. falciparum. It seems that most of the candidates identified in this study were able to elicit immune responses in the P. falciparum-infected hosts and they also played major roles in the life cycle, pathogenicity and key pathways of this parasite. [ABSTRACT FROM AUTHOR]

This paper shows how the structure and dynamics of a lightlike thin shell in general relativity can be obtained from a distributional approach.

Colombeau's generalized functions are used to adapt the distributional approach to singular hypersurfaces in general relativity with signature change. Equations governing the dynamics of a singular hypersurface are derived and a specific non-vanishing form for the energy-momentum tensor of the singular hypersurface is obtained. It is shown that matching in the case of de Sitter space in the Lorentzian sector is possible along the boundary with minimum radius but leads to the vanishing of the energy-momentum tensor of the singular hypersurface.

Time variation of the Newtonian gravitational constant, G, is studied in model universes with a variable space dimension proposed recently. Using the Lagrangian formulation of these models, we find the effective gravitational constant as a function of time. To compare it with observational data, a test theory for the time variation of Gis formulated. We have assumed a power law behavior of the time variation of Gwhere the exponent βis itself time dependent. Within this test theory we are able to restrict the free parameter of the theories under consideration and give upper bounds for the space dimension at the Planck era. The time variation of Gat earlier times, such as the time of nucleosynthesis is also predicted which express the needs to look for related observational data.

Kinematically viable space-time theories admitting a velocity-dependent dilatation factor in addition to the Lorentz transformation between the inertial systems are considered. It is shown that these theories are very unsatisfactory, in the sense of leading neither to a unique definition of time nor to a unique formulation of a dynamics. As an example, the relativistic theory of anisotropic spacetime proposed by Bogoslovsky is shown to differ discretely from the special theory of relativity. First-order rotor experiments restrict the free parameter r in this theory to values smaller than 10-10

The role of convention in various definitions of clock synchronization and simultaneity is investigated. We show that two principal methods of synchronization can be considered: system internal and system external synchronization. Synchronization by the Einstein procedure and by slow clock transport turn out to be equivalent if and only if the time dilatation factor is given by the Einstein result (1−v2)1/2. An ether theory is constructed that maintains absolute simultaneity and is kinematically equivalent to special relativity.

First-order tests of special relativity are based on a comparison of clocks synchronized with the help of slow clock transport with those synchronized by the Einstein procedure. This comparison enables the measurement of the one-way velocity of light and is equivalent to a measurement of the time dilatation factor. The accuracy of present measurements is of the order 10−7, yielding an upper limit of 3 cm/sec for the ether drift.

Various second-order optical tests of special relativity are discussed within the framework of the test theory developed previously. Owing to the low accuracy of the Kennedy-Thorndike experiment, the Lorentz contraction is known by direct experiments only to an accuracy of a few percent. To improve this-accuracy several experiments are suggested.

We use an exact general relativistic model structure within a Friedmann-Robertson-Walker cosmological background based on a Lemaître, Tolman, and Bondi metric to study the gravitational lensing by a cosmological and dynamical structure. Using different density profiles for the model structure, the deviation angle and the time delay through the gravitational lensing has been studied by solving the geodesic equations. The results of these exact calculations have been compared to the thin lens approximation. We have shown that the result for the thin lens approximation based on a modified Navarro-Frenk-White density profile with a void before going over to the Friedmann-Robertson-Walker background matches very well with the exact general relativistic calculations. However, the thin lens approximation based on a normal Navarro-Frenk-White profile does differ from the exact relativistic calculation. The difference is more the less compact the structure is. We have also looked at the impact of our calculation on the observational interpretation of arcs in the case of strong lensing and also the reduced shear in the case of weak lensing. No significant difference has been seen in the data available. [ABSTRACT FROM AUTHOR]