Antifungal activity and mode of action of synthetic peptides derived from the tick OsDef2 defensin.

Candida albicans is the principal opportunistic fungal pathogen in nosocomial settings and resistance to antifungal drugs is on the rise. Antimicrobial peptides from natural sources are promising novel therapeutics against C. albicans.

Histological analysis of the effects of cadmium, chromium and mercury alone and in combination on the spleen of male Sprague-Dawley rats.

The mining sector in South Africa is expected to be the fifth largest in the world. Both mining and transport are the most common reasons for an increased risk of human exposure to heavy metal contamination in South Africa. Due to increasing amounts of metals in the environment, this study identified three metals cadmium, chromium and mercury based on the risk of exposure in South Africa.

The dual functionality of antimicrobial peptides Os and Os-C in human leukocytes.

Antimicrobial peptides (AMPs), Os and Os-C, have been identified as multifunctional peptides with antibacterial, antiendotoxin, and anti-inflammatory properties. For further development of Os and Os-C as therapeutic peptides, it is essential to evaluate these effects in human mononuclear (MN) and polymorphonuclear (PMN) leukocytes. The cytotoxicity and the effects of both peptides on MN and PMN morphology were determined with the Alamar-Blue assay and scanning electron microscopy, respectively.

Investigation into the mechanism of action of the antimicrobial peptides Os and Os-C derived from a tick defensin.

Os and Os-C are two novel antimicrobial peptides, derived from a tick defensin, which have been shown to have a larger range of antimicrobial activity than the parent peptide, OsDef2. The aim of this study was to determine whether the peptides Os and Os-C are mainly membrane acting, or if these peptides have possible additional intracellular targets in Escherichia coli and Bacillus subtilis. Transmission electron microscopy revealed that both peptides adversely affected intracellular structure of both bacteria causing different degrees of granulation of the intracellular contents.

A descriptive study to provide evidence of the teratogenic and cellular effects of sibutramine and ephedrine on cardiac- and liver-tissue of chick embryos.

Exposure to drugs during pregnancy is a major concern, as some teratogenic compounds can influence normal foetal development. Although the use of drugs during pregnancy should generally be avoided, exposure of the developing foetus to teratogens may occur unknowingly since these compounds may be hidden in products that are being marketed as "all natural." The aim of the current study was to investigate the possible teratogenic and cellular effects of sibutramine-a serotonin-norepinephrine reuptake inhibitor used in the treatment of obesity-on the heart and liver tissue of chick embryos.

An in ovo investigation into the hepatotoxicity of cadmium and chromium evaluated with light- and transmission electron microscopy and electron energy-loss spectroscopy.

Excessive agriculture, transport and mining often lead to the contamination of valuable water resources. Communities using this water for drinking, washing, bathing and the irrigation of crops are continuously being exposed to these heavy metals. The most vulnerable is the developing fetus.

Premature collagen fibril formation, fibroblast-mast cell interactions and mast cell-mediated phagocytosis of collagen in keloids.

Keloids are benign hyper-proliferative growths of fibrous tissue where increased fibroblast activity results in abnormal collagen deposition. Excessive inflammation is a characteristic feature of keloids, but little is known about the underlying ultrastructural features of keloids related to collagen processing, fibril and fiber formation, the interaction between fibroblasts and associated collagen fibers and mast cells. In this study, the ultrastructure of the dermis of keloid patients was evaluated using light and transmission electron microscopy techniques.

Feasibility of high pressure freezing with freeze substitution after long-term storage in chemical fixatives.

Fixation of biological samples is an important process especially related to histological and ultrastructural studies. Chemical fixation was the primary method of fixing tissue for transmission electron microscopy for many years, as it provides adequate preservation of the morphology of cells and organelles. High pressure freezing (HPF) and freeze substitution (FS) is a newer alternative method that rapidly freezes non-cryoprotected samples that are then slowly heated in the FS medium, allowing penetration of the tissue to insure adequate fixation.

Structural and functional characterization of peptides derived from the carboxy-terminal region of a defensin from the tick Ornithodoros savignyi.

Tick defensins may serve as templates for the development of multifunctional peptides. The purpose of this study was to evaluate shorter peptides derived from tick defensin isoform 2 (OsDef2) in terms of their antibacterial, antioxidant, and cytotoxic activities. We compared the structural and functional properties of a synthetic peptide derived from the carboxy-terminal of the parent peptide (Os) to that of an analogue in which the three cysteine residues were omitted (Os-C).