Biometals 

About: Biometals is an academic journal published by Springer Science+Business Media. The journal publishes majorly in the area(s): Medicine & Chemistry. It has an ISSN identifier of 0966-0844. Over the lifetime, 2294 publications have been published receiving 83966 citations.

Cadmium stress: an oxidative challenge

Abstract: At the cellular level, cadmium (Cd) induces both damaging and repair processes in which the cellular redox status plays a crucial role. Being not redox-active, Cd is unable to generate reactive oxygen species (ROS) directly, but Cd-induced oxidative stress is a common phenomenon observed in multiple studies. The current review gives an overview on Cd-induced ROS production and anti-oxidative defense in organisms under different Cd regimes. Moreover, the Cd-induced oxidative challenge is discussed with a focus on damage and signaling as downstream responses. Gathering these data, it was clear that oxidative stress related responses are affected during Cd stress, but the apparent discrepancies observed in between the different studies points towards the necessity to increase our knowledge on the spatial and temporal ROS signature under Cd stress. This information is essential in order to reveal the exact role of Cd-induced oxidative stress in the modulation of downstream responses under a diverse array of conditions.

Antifungal activity and mode of action of silver nano-particles on Candida albicans

Abstract: In this study, the antifungal effects of silver nano-particles (nano-Ag) and their mode of action were investigated. Nano-Ag showed antifungal effects on fungi tested with low hemolytic effects against human erythrocytes. To elucidate the antifungal mode of action of nano-Ag, flow cytometry analysis, a glucose-release test, transmission electron microscopy (TEM) and the change in membrane dynamics using 1,6-diphenyl-1,3,5-hexatriene (DPH), as a plasma membrane probe, were performed with Candida albicans. The results suggest nano-Ag may exert an antifungal activity by disrupting the structure of the cell membrane and inhibiting the normal budding process due to the destruction of the membrane integrity. The present study indicates nano-Ag has considerable antifungal activity, deserving further investigation for clinical applications.

Zinc coordination sphere in biochemical zinc sites

Abstract: Zinc is known to be indispensable to growth and development and transmission of the genetic message. It does this through a remarkable mosaic of zinc binding motifs that orchestrate all aspects of metabolism. There are now nearly 200 three dimensional structures for zinc proteins, representing all six classes of enzymes and covering a wide range of phyla and species. These structures provide standards of reference for the identity and nature of zinc ligands in other proteins for which only the primary structure is known. Three primary types of zinc sites are apparent from examination of these structures: structural, catalytic and cocatalytic. The most common amino acids that supply ligands to these sites are His, Glu, Asp and Cys. In catalytic sites zinc generally forms complexes with water and any three nitrogen, oxygen and sulfur donors with His being the predominant amino acid chosen. Water is always a ligand to such sites. Structural zinc sites have four protein ligands and no bound water molecule. Cys is the preferred ligand in such sites. Cocatalytic sites contain two or three metals in close proximity with two of the metals bridged by a side chain moiety of a single amino acid residue, such as Asp, Glu or His and sometimes a water molecule. Asp and His are the preferred amino acids for these sites. No Cys ligands are found in such sites. The scaffolding of the zinc sites is also important to the function and reactivity of the bound metal. The influence of zinc on quaternary protein structure has led to the identification of a fourth type of zinc binding site, protein interface. In this case zinc sites are formed from ligands supplied from amino acid residues residing in the binding surface of two proteins. The resulting zinc site usually has the coordination properties of a catalytic or structural zinc binding site.

Functions of zinc in signaling, proliferation and differentiation of mammalian cells.

Abstract: Zinc is essential for cell proliferation and differentiation, especially for the regulation of DNA synthesis and mitosis. On the molecular level, it is a structural constituent of a great number of proteins, including enzymes of cellular signaling pathways and transcription factors. Zinc homeostasis in eukaryotic cells is controlled on the levels of uptake, intracellular sequestration in zinc storing vesicles ('zincosomes'), nucleocytoplasmic distribution and elimination. These processes involve the major zinc binding protein metallothionein as a tool for the regulation of the cellular zinc level and the nuclear translocation of zinc in the course of the cell cycle and differentiation. In addition, there is also increasing evidence for a direct signaling function for zinc on all levels of signal transduction. Zinc can modulate cellular signal recognition, second messenger metabolism, protein kinase and protein phosphatase activities, and it may stimulate or inhibit activities of transcription factors, depending on the experimental systems studied. Zinc has been shown to modify specifically the metabolism of cGMP, the activities of protein kinase C and mitogen activated protein kinases, and the activity of transcription factor MTF-1 which controls the transcription of the genes for metallothionein and the zinc transporter ZnT-1. As a conclusion of these observations new hypotheses regarding regulatory functions of zinc ions in cellular signaling pathways are proposed.

Heavy metal poisoning: the effects of cadmium on the kidney

Abstract: The heavy metal cadmium (Cd) is known to be a widespread environmental contaminant and a potential toxin that may adversely affect human health. Exposure is largely via the respiratory or gastrointestinal tracts; important non-industrial sources of exposure are cigarette smoke and food (from contaminated soil and water). The kidney is the main organ affected by chronic Cd exposure and toxicity. Cd accumulates in the kidney as a result of its preferential uptake by receptor-mediated endocytosis of freely filtered and metallothionein bound Cd (Cd-MT) in the renal proximal tubule. Internalised Cd-MT is degraded in endosomes and lysosomes, releasing free Cd(2+) into the cytosol, where it can generate reactive oxygen species (ROS) and activate cell death pathways. An early and sensitive manifestation of chronic Cd renal toxicity, which can be useful in individual and population screening, is impaired reabsorption of low molecular weight proteins (LMWP) (also a receptor-mediated process in the proximal tubule) such as retinol binding protein (RBP). This so-called 'tubular proteinuria' is a good index of proximal tubular damage, but it is not usually detected by routine clinical dipstick testing for proteinuria. Continued and heavy Cd exposure can progress to the clinical renal Fanconi syndrome, and ultimately to renal failure. Environmental Cd exposure may be a significant contributory factor to the development of chronic kidney disease, especially in the presence of other co-morbidities such as diabetes or hypertension; therefore, the sources and environmental impact of Cd, and efforts to limit Cd exposure, justify more attention.