Probing the structural requirements for vitamin D3 inhibition of the hedgehog signaling pathway

A structure-activity relationship study to elucidate the structural basis for hedgehog (Hh) signaling inhibition by vitamin D3 (VD3) was performed. Functional and non-functional regions of VD3 and VD2 were obtained through straightforward synthetic means and their biological activity was determined in a variety of cell-based assays. Several of these compounds inhibited Hh signaling at levels comparable to the parent VD3 with no effects on canonical vitamin D signaling. Most notably, compounds 5 and 9, demonstrated potent inhibition of the Hh pathway, exhibited no binding affinity for the vitamin D receptor (VDR), and did not activate VDR in cell culture. In addition, several compounds exhibited anti-proliferative activity against two human cancer cell lines through a mechanism distinct from the Hh or VDR pathways, suggesting a new cellular mechanism of action for this class of compounds.     

Prostaglandin E₂ increases both osteoblastic and osteoclastic activity in the scales and participates in calcium metabolism in goldfish

Using our original in vitro assay system with goldfish scales, we examined the direct effect of prostaglandin E? (PGE?) on osteoclasts and osteoblasts in teleosts. In this assay system, we measured the activity of alkaline phosphatase (ALP) and tartrate-resistant acid phosphatase (TRAP) as respective indicators of each activity in osteoblasts and osteoclasts. ALP activity in scales significantly increased following treatment at high concentration of PGE?(10?? and 10?? M) over 6 hrs of incubation. At 18 hrs of incubation, ALP activity also significantly increased in the PGE? (10?? to 10?? M)-treated scale. In the case of osteoclasts, TRAP activity tended to increase at 6 hrs of incubation, and then significantly increased at 18 hrs of incubation by PGE? (10(-7) to 10?? M) treatment. At 18 hrs of incubation, the mRNA expression of osteoclastic markers (TRAP and cathepsin K) and receptor activator of the NF-κB ligand (RANKL), an activating factor of osteoclasts expressed in osteoblasts, increased in PGE? treated-scales. Thus, PGE? acts on osteoblasts, and then increases the osteoclastic activity in the scales of goldfish as it does in the bone of mammals. In an in vivo experiment, plasma calcium levels and scale TRAP and ALP activities in the PGE?-injencted goldfish increased significantly. We conclude that, in teleosts, PGE? activates both osteoblasts and osteoclasts and participates in calcium metabolism.     

Removal of copper by Pseudomonas putida strain S4 isolated from copper mines

A bacterial strain, Pseudomonas putida S4, was isolated from smelter drainage of copper mines. The strain exhibited resistance to several heavy metals, like aluminium (Al), zinc (Zn), nickel (Ni), cobalt (Co) besides copper (Cu). Strain S4 could accumulate Cu from the Cu-supplemented growth medium. In the present study, we have demonstrated the Cu2+ removal capacity of this strain from various samples such as mine effluent, low-grade ore and ore-tailings, collected from the mining site. Moreover, approximately 80% of the accumulated Cu2+ could be recovered from the loaded biomass by a simple desorption procedure.     

The Rad51 paralog complex Rad55-Rad57 acts as a molecular chaperone during homologous recombination

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Curative effect of 18β-glycyrrhetinic acid in experimental visceral leishmaniasis depends on phosphatase-dependent modulation of cellular MAP kinases

We earlier showed that 18β-glycyrrhetinic acid (GRA), a pentacyclic triterpenoid from licorice root, could completely cure visceral leishmaniasis in BALB/c mouse model. This was associated with induction of nitric oxide and proinflammatory cytokine production through the up regulation of NF-κB. In the present study we tried to decipher the underlying cellular mechanisms of the curative effect of GRA. Analysis of MAP kinase pathways revealed that GRA caused strong activation of p38 and to a lesser extent, ERK in bone marrow-derived macrophages (BMDM). Almost complete abrogation of GRA-induced cytokine production in presence of specific inhibitors of p38 and ERK1/2 confirmed the involvement of these MAP kinases in GRA-mediated responses. GRA induced mitogen- and stress-activated protein kinase (MSK1) activity in a time-dependent manner suggested that GRA-mediated NF-κB transactivation is mediated by p38, ERK and MSK1 pathway. As kinase/phosphatase balance plays an important role in modulating infection, the effect of GRA on MAPK directed phosphatases (MKP) was studied. GRA markedly reduced the expression and activities of three phosphatases, MKP1, MKP3 and protein phosphatase 2A (PP2A) along with a substantial reduction of p38 and ERK dephosphorylation in infected BMDM. Similarly in the in vivo situation, GRA treatment of L. donovani-infected BALB/c mice caused marked reduction of spleen parasite burden associated with concomitant decrease of individual phosphatase levels. However, activation of kinases also played an important role as the protective effect of GRA was significantly abrogated by pharmacological inhibition of p38 and ERK pathway. Curative effect of GRA may, therefore, be associated with restoration of proper cellular kinase/phosphatase balance, rather than modulation of either kinases or phosphatases.     

BK Polyomavirus Genotypes Represent Distinct Serotypes with Distinct Entry Tropism

BK polyomavirus (BKV) causes significant urinary tract pathogenesis in immunosuppressed individuals, including kidney and bone marrow transplant recipients. It is currently unclear whether BKV-neutralizing antibodies can moderate or prevent BKV disease. We developed reporter pseudoviruses based on seven divergent BKV isolates and performed neutralization assays on sera from healthy human subjects. The results demonstrate that BKV genotypes I, II, III, and IV are fully distinct serotypes. While nearly all healthy subjects had BKV genotype I-neutralizing antibodies, a majority of subjects did not detectably neutralize genotype III or IV. Surprisingly, BKV subgenotypes Ib1 and Ib2 can behave as fully distinct serotypes. This difference is governed by as few as two residues adjacent to the cellular glycan receptor-binding site on the virion surface. Serological analysis of mice given virus-like particle (VLP)-based BKV vaccines confirmed these findings. Mice administered a multivalent VLP vaccine showed high-titer serum antibody responses that potently cross-neutralized all tested BKV genotypes. Interestingly, each of the neutralization serotypes bound a distinct spectrum of cell surface receptors, suggesting a possible connection between escape from recognition by neutralizing antibodies and cellular attachment mechanisms. The finding implies that different BKV genotypes have different cellular tropisms and pathogenic potentials in vivo. Individuals who are infected with one BKV serotype may remain humorally vulnerable to other BKV serotypes after implementation of T cell immunosuppression. Thus, prevaccinating organ transplant recipients with a multivalent BKV VLP vaccine might reduce the risk of developing posttransplant BKV disease.     

Cytoarchitectural alterations in kidney of Wistar rat after oral exposure to cadmium chloride

Male Wistar rats were randomly divided into three groups - A, B and C. A dose of 5 mg and 10 mg of cadmium chloride/kg body weight/day was orally administered to groups B and C, respectively. Rats from group A served as control. Rats were sacrificed on 1st, 2nd, 4th, 6th, and 8th week after initiation of the experiment. Kidneys were removed immediately, fixed in Bouin's fixative, routinely processed and stained with hematoxylin and eosin. The present study showed that the histopathological changes were caused in kidney of rats by cadmium exposure. The changes noticed were mainly - the glomerular swelling (at initial stage), the shrinkage of glomerulus (at later stage), the tubular dilatation, hypertrophy of tubular epithelium, degeneration of glomerulus and renal tubules and deposition of eosin-positive substances in the glomerulus and renal tubules. However, lesions were depended upon the doses and duration of the treatment.     

Eosinophils and Megakaryocytes Support the Early Growth of Murine MOPC315 Myeloma Cells in Their Bone Marrow Niches

Multiple myeloma is a bone marrow plasma cell tumor which is supported by the external growth factors APRIL and IL-6, among others. Recently, we identified eosinophils and megakaryocytes to be functional components of the micro-environmental niches of benign bone marrow plasma cells and to be important local sources of these cytokines. Here, we investigated whether eosinophils and megakaryocytes also support the growth of tumor plasma cells in the MOPC315.BM model for multiple myeloma. As it was shown for benign plasma cells and multiple myeloma cells, IL-6 and APRIL also supported MOPC315.BM cell growth in vitro, IL-5 had no effect. Depletion of eosinophils in vivo by IL-5 blockade led to a reduction of the early myeloma load. Consistent with this, myeloma growth in early stages was retarded in eosinophil-deficient ΔdblGATA-1 mice. Late myeloma stages were unaffected, possibly due to megakaryocytes compensating for the loss of eosinophils, since megakaryocytes were found to be in contact with myeloma cells in vivo and supported myeloma growth in vitro. We conclude that eosinophils and megakaryocytes in the niches for benign bone marrow plasma cells support the growth of malignant plasma cells. Further investigations are required to test whether perturbation of these niches represents a potential strategy for the treatment of multiple myeloma.