Stress impact of liposomes loaded with ciprofloxacin on the expression level of MepA and NorB efflux pumps of methicillin-resistant Staphylococcus aureus

International Microbiology - One mechanism of ciprofloxacin resistance is attributed to chromosomal DNA-encoded efflux pumps such as the MepA and NorB proteins. The goal of this research is to find...     

Cutting edge: induced indoleamine 2,3 dioxygenase expression in dendritic cell subsets suppresses T cell clonal expansion

In mice, immunoregulatory APCs express the dendritic cell (DC) marker CD11c, and one or more distinctive markers (CD8alpha, B220, DX5). In this study, we show that expression of the tryptophan-degrading enzyme indoleamine 2,3 dioxygenase (IDO) is selectively induced in specific splenic DC subsets when mice were exposed to the synthetic immunomodulatory reagent CTLA4-Ig. CTLA4-Ig did not induce IDO expression in macrophages or lymphoid cells. Induction of IDO completely blocked clonal expansion of T cells from TCR transgenic mice following adoptive transfer, whereas CTLA4-Ig treatment did not block T cell clonal expansion in IDO-deficient recipients. Thus, IDO expression is an inducible feature of specific subsets of DCs, and provides a potential mechanistic explanation for their T cell regulatory properties.     

Microbial transformation of delta 9(15)-africanene

Incubation of delta 9(15)-africanene with fungi Aspergillus niger and Rhizopus oryzae for 8 days yielded two oxidized derivatives, 10 alpha-hydroxy-delta 9(15)-africanene and 9 alpha,15-epoxyafricanane. The structure of the two products were assigned by interpretation of their spectral data.     

Hoxa9 transforms primary bone marrow cells through specific collaboration with Meis1a but not Pbx1b.

Hoxa9, Meis1 and Pbx1 encode homeodomaincontaining proteins implicated in leukemic transformation in both mice and humans. Hoxa9, Meis1 and Pbx1 proteins have been shown to physically interact with each other, as Hoxa9 cooperatively binds consensus DNA sequences with Meis1 and with Pbx1, while Meis1 and Pbx1 form heterodimers in both the presence and absence of DNA. In this study, we sought to determine if Hoxa9 could transform hemopoietic cells in collaboration with either Pbx1 or Meis1. Primary bone marrow cells, retrovirally engineered to overexpress Hoxa9 and Meis1a simultaneously, induced growth factor-dependent oligoclonal acute myeloid leukemia in <3 months when transplanted into syngenic mice. In contrast, overexpression of Hoxa9, Meis1a or Pbx1b alone, or the combination of Hoxa9 and Pbx1b failed to transform these cells acutely within 6 months post-transplantation. Similar results were obtained when FDC-P1 cells, engineered to overexpress these genes, were transplanted to syngenic recipients. Thus, these studies demonstrate a selective collaboration between a member of the Hox family and one of its DNA-binding partners in transformation of hemopoietic cells.     

An investigation of the homology of guanylate kinase isozymes in mammals and further evidence for multiple GUK gene loci

Guanylate kinase in the red cells of 63 different mammalian species was studied by electrophoresis and multiple molecular forms of the enzyme were found in all species. Two species were investigated in more detail. Using molecular weight estimates as a criterion of homology, the fallow deer and the Chinese hamster were found to have isozymes that corresponded to isozyme e, f, and g of man. Variation in the guanylate kinase isozymes was detected in a small population of orangutans. Results suggested that isozymes a and b were monomeric and that they were the products of a gene locus, GUK1, different from the locus GUK3 which coded for isozymes e, f, and g. Products c and d of the presumptive GUK2 locus were not found in the orangutan.     

The effect of benzyl penicillin on the ultrastructure of Neisseria gonorrhoeae

Electron microscopy of Neisseria gonorrhoeae grown on solid medium with a subinhibitory concentration of penicillin suggested that the amount of penicillin reaching each pair of gonococci was different, as illustrated by the ultrastructural appearance of N, gonorrhoeae cells in the colony. This supports the view that the concentration of penicillin in different parts of the colony is not uniform, causing some cells to lyse while the others remain intact.     

Mannich reaction: an approach for the synthesis of water soluble mulundocandin analogues

Semisynthetic modifications at Hydroxy tyrosine (Htyr) unit of mulundocandin (1) were carried out to improve its aqueous solubility. A single step introduction of substituted aminomethyl groups at the ortho position(s) of phenolic hydroxyl of HTyr unit of mulundocandin has been achieved in 7-85% yield. The in vitro screening of Mannich products against Candida albicans and Aspergillus fumigatus, retained the in vivo activity of parent by oral and intraperitoneal route. Compound 20, showed significant improvement in activity over mulundocandin (1) and activity compares well with that of fluconazole.     

A rapid identification system for metallothionein proteins using expert system

Metallothioneins (MT) are low molecular weight proteins mostly rich in cysteine residues with high metal content. Generally, MT proteins are responsible for regulating the intracellular supply of biologically essential metal ions and they protect cells from the deleterious effects of non-essential polarizable transition and post-transition metal ions. Due to their biological importance, proper characterization of MT is necessary. Here we describe a computer program (ID3 algorithm, a part of Artificial Intelligence) developed using available data for the rapid identification of MT. Tissue samples contains several low molecular weight proteins with different physical, chemical and biological characteristics. The described software solution proposes to categorize MT proteins without aromatic amino acids and high metal content. The proposed solution can be expanded to other types of proteins with specific known characteristics.