Effects of chronic treatment with sodium tetrachloroaurate(III) in mice and membrane models

Gold is a nonessential element with a variety of applications in medicine. A few gold(I) compounds are used in the clinics for treatment of rheumatoid arthritis and of discoid lupus. Some novel gold(III) compounds are under evaluation as anticancer agents. It is known that gold compounds generally produce toxic effects on the kidneys and characteristic lesions in the brain. However, information concerning the neurotoxicity of gold derivatives in humans as well as in experimental toxicology is rather scarce. For this reason we tried to shed some further light on this aspect of gold neurotoxicity by chronic treatment of mice with sodium tetrachloroaurate(III) in order to observe possible biophysical and morphological alterations that may occur in the brain. Chronic gold treatment resulted in a markedly decreased expression of metallothioneins and of glial fibrillary acidic protein in astrocytes of different brain areas. To examine its effects on cell membranes, interactions of sodium tetrachloroaurate(III) with molecular models were also evaluated. The models consisted in bilayers built-up of classes of phospholipids located in the outer and inner monolayers of biological membranes. Structural perturbation of cell membrane models was observed only at concentrations 10(5) times higher than those detected in the brains of animals after three months' treatment. These results show that toxic effects on animal brain upon treatment with sodium tetrachloroaurate develop with difficulty and may be observed only at high doses.     

Transmission patterns of Leishmania tropica around the Mediterranean basin: Could Morocco be impacted by a zoonotic spillover?

Cutaneous leishmaniasis (CL) due to Leishmania tropica is a neglected tropical disease characterized by a wide geographical distribution in the Mediterranean basin and is endemic in several of its countries. In addition, the vector Phlebotomus sergenti is abundantly present all around the basin. Its transmission cycle is still subject to debate. In some countries, the presence of an animal reservoir has been confirmed. In Morocco, CL due to L. tropica has risen since the 1980s and has spread widely to become the most abundant form of leishmaniasis in the territory. However, the anthroponotic transmission is so far the only recognized mode, despite recordings of L. tropica infection in animal hosts. In this review article, we assess the situation of CL due to L. tropica in the Mediterranean basin with a focus on Morocco and gather knowledge about any potential zoonotic transmission in the country. A concomitant zoonotic transmission could explain the persistence of the disease in areas where human protective measures combined with vector management did not help reduce the disease burden.     

Tryptophan (W) at position 37 of murine IL-12/IL-23 p40 is mandatory for binding to IL-12Rβ1 and subsequent signal transduction

Interleukin (IL)-12 and IL-23 are composite cytokines consisting of p35/p40 and p19/p40, respectively, which signal via the common IL-12 receptor β1 (IL-12Rβ1) and the cytokine-specific receptors IL-12Rβ2 and IL-23R. Previous data showed that the p40 component interacts with IL-12Rβ1, whereas p19 and p35 subunits solely bind to IL-23R and IL-12Rβ2, resulting in tetrameric signaling complexes. In the absence of p19 and p35, p40 forms homodimers and may induce signaling via IL-12Rβ1 homodimers. The critical amino acids of p19 and p35 required for binding to IL-23R and IL-12Rβ2 are known, and two regions of p40 critical for binding to IL-12Rβ1 have recently been identified. In order to characterize the involvement of the N-terminal region of p40 in binding to IL-12Rβ1, we generated deletion variants of the p40-p19 fusion cytokine. We found that an N-terminal deletion variant missing amino acids M23 to P39 failed to induce IL-23-dependent signaling and did not bind to IL-12Rβ1, whereas binding to IL-23R was maintained. Amino acid replacements showed that p40W37K largely abolished IL-23-induced signal transduction and binding to IL-12Rβ1, but not binding to IL-23R. Combining p40W37K with D36K and T38K mutations eliminated the biological activity of IL-23. Finally, homodimeric p40D36K/W37K/T38K did not interact with IL-12Rβ1, indicating binding of homodimeric p40 to IL-12Rβ1 is comparable to the interaction of IL-23/IL-12 and IL-12Rβ1. In summary, we have defined D36, W37, and T38 as hotspot amino acids for the interaction of IL-12/IL-23 p40 with IL-12Rβ1. Structural insights into cytokine–cytokine receptor binding are important to develop novel therapeutic strategies.     

Sporotrichosis Successfully Treated with Terbinafine and Potassium Iodide: Case Report and Review of the Literature

Sporotrichosis is rare in Turkey. We report a 40-year-old woman who had subcutaneous sporotrichosis caused by sporothrix schenckii that was successfully treated with terbinafine (250 mg, twice a day) for a period of 6 months. She received a saturated solution of potassium iodide orally for two months. Terbinafine and potassium iodide are suggested to be the agents of choice for treatment of subcutaneous sporotrichosis.     

The S1P2 receptor negatively regulates platelet-derived growth factor-induced motility and proliferation

Sphingosine-1-phosphate (S1P), a bioactive sphingolipid metabolite, is the ligand for five specific G protein-coupled receptors, named S1P(1) to S1P(5). In this study, we found that cross-communication between platelet-derived growth factor receptor and S1P(2) serves as a negative damper of PDGF functions. Deletion of the S1P(2) receptor dramatically increased migration of mouse embryonic fibroblasts toward S1P, serum, and PDGF but not fibronectin. This enhanced migration was dependent on expression of S1P(1) and sphingosine kinase 1 (SphK1), the enzyme that produces S1P, as revealed by downregulation of their expression with antisense RNA and small interfering RNA, respectively. Although S1P(2) deletion had no significant effect on tyrosine phosphorylation of the PDGF receptors or activation of extracellular signal-regulated kinase 1/2 or Akt induced by PDGF, it reduced sustained PDGF-dependent p38 phosphorylation and markedly enhanced Rac activation. Surprisingly, S1P(2)-null cells not only exhibited enhanced proliferation but also markedly increased SphK1 expression and activity. Conversely, reintroduction of S1P(2) reduced DNA synthesis and expression of SphK1. Thus, S1P(2) serves as a negative regulator of PDGF-induced migration and proliferation as well as SphK1 expression. Our results suggest that a complex interplay between PDGFR and S1P receptors determines their functions.     

A novel acylglycerol kinase that produces lysophosphatidic acid modulates cross talk with EGFR in prostate cancer cells

The bioactive phospholipids, lysophosphatidic acid (LPA) and phosphatidic acid (PA), regulate pivotal processes related to the pathogenesis of cancer. Here, we report characterization of a novel lipid kinase, designated acylglycerol kinase (AGK), that phosphorylates monoacylglycerol and diacylglycerol to form LPA and PA, respectively. Confocal microscopy and subcellular fractionation suggest that AGK is localized to the mitochondria. AGK expression was up-regulated in prostate cancers compared with normal prostate tissues from the same patient. Expression of AGK in PC-3 prostate cancer cells markedly increased formation and secretion of LPA. This increase resulted in concomitant transactivation of the EGF receptor and sustained activation of extracellular signal related kinase (ERK) 1/2, culminating in enhanced cell proliferation. AGK expression also increased migratory responses. Conversely, down-regulating expression of endogenous AGK inhibited EGF- but not LPA-induced ERK1/2 activation and progression through the S phase of the cell cycle. Hence, AGK can amplify EGF signaling pathways and may play an important role in the pathophysiology of prostate cancer.     

Cyclosporine A Impairs Nucleotide Binding Oligomerization Domain (Nod1)-Mediated Innate Antibacterial Renal Defenses in Mice and Human Transplant Recipients

Acute pyelonephritis (APN), which is mainly caused by uropathogenic Escherichia coli (UPEC), is the most common bacterial complication in renal transplant recipients receiving immunosuppressive treatment. However, it remains unclear how immunosuppressive drugs, such as the calcineurin inhibitor cyclosporine A (CsA), decrease renal resistance to UPEC. Here, we investigated the effects of CsA in host defense against UPEC in an experimental model of APN. We show that CsA-treated mice exhibit impaired production of the chemoattractant chemokines CXCL2 and CXCL1, decreased intrarenal recruitment of neutrophils, and greater susceptibility to UPEC than vehicle-treated mice. Strikingly, renal expression of Toll-like receptor 4 (Tlr4) and nucleotide-binding oligomerization domain 1 (Nod1), neutrophil migration capacity, and phagocytic killing of E. coli were significantly reduced in CsA-treated mice. CsA inhibited lipopolysaccharide (LPS)-induced, Tlr4-mediated production of CXCL2 by epithelial collecting duct cells. In addition, CsA markedly inhibited Nod1 expression in neutrophils, macrophages, and renal dendritic cells. CsA, acting through inhibition of the nuclear factor of activated T-cells (NFATs), also markedly downregulated Nod1 in neutrophils and macrophages. Silencing the NFATc1 isoform mRNA, similar to CsA, downregulated Nod1 expression in macrophages, and administration of the 11R-VIVIT peptide inhibitor of NFATs to mice also reduced neutrophil bacterial phagocytosis and renal resistance to UPEC. Conversely, synthetic Nod1 stimulating agonists given to CsA-treated mice significantly increased renal resistance to UPEC. Renal transplant recipients receiving CsA exhibited similar decrease in NOD1 expression and neutrophil phagocytosis of E. coli. The findings suggest that such mechanism of NFATc1-dependent inhibition of Nod1-mediated innate immune response together with the decrease in Tlr4-mediated production of chemoattractant chemokines caused by CsA may contribute to sensitizing kidney grafts to APN.     

State of the art in the functioning of shallow Mediterranean lakes: workshop conclusions

Studies on shallow lakes from the north temperate zone show that they alternate between clear and turbid water states in response to control factors. However, the ecology of semi-arid to arid shallow Mediterranean lakes is less explored. Hydrological effects (e.g. water level fluctuations, water residence time) on major ions and nutrient dynamics and processes, and ecology of submerged macrophytes appear to have a crucial role for food webs in shallow Mediterranean lakes. Nutrient control may be of greater priority in eutrophicated warm shallow lakes than in similar lakes at higher latitudes. This will be relevant for the implementation of the European Water Framework Directive, and conservation and management of these ecosystems. Strong trophic cascading effects of fish resulting from dominance of omnivorous and benthivorous fish species, whose diversity is usually high, together with frequent spawning and absence of efficient piscivores, seem to be the reason for the lack of large-bodied grazers that could control phytoplankton. However, such effects may vary within the region depending on fish distribution and community. These factors need elaboration in order to allow shallow lake ecologists and managers to develop better restoration strategies for eutrophicated shallow Mediterranean lakes. Consequently, modifications for the implementation of the European Water Framework Directive for determining ecological status in shallow Mediterranean lakes appear to be necessary. Furthermore, the implications of climate warming may be even more challenging than in high latitude lakes since shallow lakes in the Mediterranean region are among the most sensitive to extreme climate changes. There is an urgent need for data on the ecology of shallow lakes in the region. An appeal is made for international cooperation, development of large-scale research and information exchange to facilitate this and a web-based discussion list has been implemented.     

Photophysical and photodynamic properties of Pyronin Y in micellar media at different temperatures

In this study, photophysics and photodynamical properties of Pyronin Y (PyY) in different liquid media were investigated. Interactions of PyY, which is a positively charged pigment compound pertaining to the xanthene derivatives with surfactants possessing distinct charges, were determined by using the molecular absorption and fluorescence spectroscopy techniques. It was observed that band intensities of absorption and fluorescence spectra belonging to PyY increase in proportion to the water when compared to three micelle systems, cetyltrimethylammonium bromide (CTAB), sodium dodecyl sulfate (SDS) and Triton X‐100 (TX‐100). This suggests that interactions in micelle systems are different from those in deionized water, and solvation and surface interactions modify. It is determined that the strongest interaction occurs between PyY dye and SDS, anionic surfactant, and this interaction arises from the electrostatic forces. Calculated photophysical parameters indicated that the microenvironment of PyY in SDS micelle is different to that of other systems. In temperature studies, it was reported that increasing the temperature of the samples increased non‐radiative transitions. Steady‐state fluorescence anisotropy values were calculated by using fluorescence intensities of PyY compound in pre‐micellar, micellar and post‐micellar systems. Once the PyY fluorescence probe is added to the surfactant containing solutions below the critical micelle concentrations, the measured anisotropy values were found to be low because the probe remains in the deionized water phase. When the surfactant concentration of the medium becomes closer to the critical micelle concentrations, the steady‐state anisotropy value prominently increases. This is because of the restrictions on the rotational diffusion of the probe in micellar solution. It is observed that positively charged PyY shows a higher affinity to the negatively charged SDS compared with the positively charged CTAB and neutral TX‐100 surfactants. This can be explained by Coulombic interactions.     

The genes encoding cAMP-dependent protein kinase catalytic subunit homologues of the microsporidia Encephalitozoon intestinalis and E. cuniculi: molecular characterisation and phylogenetic analysis

A gene encoding a protein kinase was identified by homology-based PCR amplification in Encephalitozoon intestinalis, a microsporidian parasite pathogenic to humans, and its orthologue has been identified by database mining in the genome of the related species E. cuniculi, whose sequence has been recently published. Phylogenetic analysis revealed that the proteins encoded by these genes are homologues of the cAMP-dependent protein kinase catalytic subunits (PKAc). Southern blot analysis indicated that the EiPKAc gene is present in two copies in the E. intestinalis genome, whereas the E. cuniculi orthologue (EcPKAc) is a single copy gene. RT-PCR data showed that the EiPKAc gene is expressed in at least one of the intracellular stages during infection of the mammalian host cell by E. intestinalis.