Antimicrobial peptides: a potential role in ocular therapy

Bacterial pathogens are often involved in contact lens‐related adverse responses. This study aimed to find antimicrobial peptides and proteins that effectively eradicate or inhibit ocular bacteria. The antimicrobials were screened against Gram‐ negative and Gram‐positive bacteria originating from ocular sources. The viability of these ocular bacteria was measured after exposure to the peptides and proteins. Two conditions were used to grow bacteria, low nutrient phosphate‐buffered saline and high nutrient tryptone soya broth. Samples were taken at different times up to 48 h. In low nutrient conditions, protamine was found to be the most effective against all strains. Melittin was very effective against all strains except Serratia and one Pseudomonas isolate which were partially affected. In high nutrient condition, only melittin was effective in killing Staphylococcus aureus. Protamine and the combination of protamine and melittin had the greatest effect in eradicating the bacteria tested in low nutrient condition. Protamine alone and its combination with melittin may have potential therapeutic agents for ocular infections in an era of emerging antibiotic resistance.     

Production of N-acyl homoserine lactones by Gram-negative bacteria isolated from contact lens wearers

The purpose of this study was to investigate the production of N‐acyl‐homoserine lactone (AHL) signal molecules in ocular Gram‐negative bacteria. A total of 91 ocular strains isolated from contact lens adverse response patients and asymptomatic subjects were used in the study. These included Acinetobacter, Aeromonas hydrophila, Escherichia coli, Haemophilus influenzae, Klebsiella oxytoca, Pseudomonas aeruginosa, Serratia liquefaciens, Serratia marcescens, and Stenotrophomonas maltophilia. The biosensor strains Chromobacterium violaceum mutant CV026 and Agrobacterium tumefaciens A136 were used for detection of AHL signal molecules. The majority of A. hydrophila, P. aeruginosa, and S. liquefaciens strains produced more than one AHL molecule. Serratia marcescens strains were AHL positive only under detection of A136. The rest of the test species did not show any AHL production under the current detection system. These findings indicate that AHL‐ mediated quorum‐sensing systems are present in some of the ocular bacteria, and the different signal molecules may be involved with the quorum‐sensing pathway in the other bacterial species.     

Treatment of imported cases of falciparum malaria in France with halofantrine

Halofantrine is a 9-phenanthrenemethanol which is effective against multi-drug resistant strains of Plasmodium falciparum. It has been shown to be highly effective and extremely well tolerated in the treatment of imported cases of falciparum malaria in France. A total of 1,500 mg administered in three 500 mg doses at six-hour intervals results in a 100% cure rate in semi-immune subjects. This dosage should be repeated after 14 days to obtain the same cure rate in non-immune patients. Minor clinical side effects included epigastric pains, nausea and, in one case, a skin rash.     

Recovery of locomotion after chronic spinalization in the adult cat

Cats were spinalized (T13) as adults and were trained to walk with the hindlimbs on a treadmill. After 3 weeks to 3 months and up to 1 year depending on the animal, all were capable of walking on the plantar surface of the feet and support the weight of the hindquarters. Interactive training appeared to accelerate the recovery of locomotion and maintain smooth locomotor movements. Despite the obvious loss of voluntary control and equilibrium which the experimenter partially compensated for by maintaining the thorax and/or the tail, the cats could walk with a regular rhythm and a well-coordinated hindlimb alternation at speeds of 0.1-1.2 m/s. Cycle duration as well as stance and swing duration resembled those of normal cats at comparable speeds. The range of angular motion was also similar to that observed in intact cats as was the coupling between different joints. The EMG activity of the hindlimb and lumbar axial muscles also retained the characteristics observed in the intact animal. Some deficits such as a dragging of the foot in early swing and diminution of the angular excursion in the knee were seen at later stages. Thus, the adult spinal cat preparation is considered as a useful model to study the influence of different types of training and of different drugs or other treatments in the process of locomotor recovery after injury to the spinal cord.     

Tear film,contact lenses and tear biomarkers

This article summarises research undertaken since 1993 in the Willcox laboratory at the University of New South Wales, Sydney on the tear film, its interactions with contact lenses, and the use of tears as a source of biomarkers for ocular and non‐ocular diseases. The proteome, lipidome and glycome of tears all contribute to important aspects of the tear film, including its structure, its ability to defend the ocular surface against microbes and to help heal ocular surface injuries. The tear film interacts with contact lenses in vivo and interactions between tears and lenses can affect the biocompatibility of lenses, and may be important in mediating discomfort responses during lens wear. Suggestions are made for follow‐up research.     

The Role of Electron Microscopy in Studying the Continuum of Changes in Membranous Structures during Poliovirus Infection

Replication of the poliovirus genome is localized to cytoplasmic replication factories that are fashioned out of a mixture of viral proteins, scavenged cellular components, and new components that are synthesized within the cell due to viral manipulation/up-regulation of protein and phospholipid synthesis. These membranous replication factories are quite complex, and include markers from multiple cytoplasmic cellular organelles. This review focuses on the role of electron microscopy in advancing our understanding of poliovirus RNA replication factories. Structural data from the literature provide the basis for interpreting a wide range of biochemical studies that have been published on virus-induced lipid biosynthesis. In combination, structural and biochemical experiments elucidate the dramatic membrane remodeling that is a hallmark of poliovirus infection. Temporal and spatial membrane modifications throughout the infection cycle are discussed. Early electron microscopy studies of morphological changes following viral infection are re-considered in light of more recent data on viral manipulation of lipid and protein biosynthesis. These data suggest the existence of distinct subcellular vesicle populations, each of which serves specialized roles in poliovirus replication processes.