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Virstatin is a small compound that was discovered while researchers were screening for small molecules that affected the production of toxins produced by bacteria. Current antibiotics control pathogens by targeting growth and reproduction factors. New experiments have proven that targeting the factors that make the pathogen virulent are effective in fighting infections. By stopping the production of toxins and allowing the bacteria to grow, a normal immune response is illicited which may help fight future infections. Virstatin inhibits the production of toxin and the pilus required for the pathogenicity of the cholera bacillus. Virstatin also lowered the numbers of pathogen retained in the intestinal tract-without influencing bacterial growth. This approach is still in an investigative stage however the results look promising. Traditional methods of fighting bacterial infections are proving to be less and less effective. Research must contiue to look for new ways to combat the bacteria that we are exposed to on a daily basis.

The use of antisense agents as antimicrobial drugs holds promising results. An antisense agent is a short synthetic strand of DNA that binds to a target site on the DNA or RNA of a pathogen. When this agent binds to the pathogen DNA the biosynthesis of target proteins is disrupted. This approach has a great advantage, it prevents a pathogenic protein from being produced, rather than trying to selectively neutralize it once it is made. An antiviral drug based on antisense principals, fomivirsen, has been approved for treating the eye disease cytomegalovirus retinitus. Mammalian cells have a mechanism that on occasion, can prevent RNA from giving rise to the proteins for which they are encoded. This is useful when an infecting virus takes over a host cell. This mechanism is known as RNA interference. This mechanism is more effective than antisense agents and there are no known resistance mechanisms.

One of my previous posts discussed antimicrobial resistance however it did not discuss steps to correct this problem. Antimicrobial peptides may be the solution to antimicrobial resistance. Microorganisms are not the only organisms that produce antimicrobial substances. Antimicrobial peptides are produced by birds, amphibians, plants, and mammals. These peptides are part of the defense system of most forms of life and hundreds of peptides have been identified. These peptides have fewer than 100 amino acids and carry a positive electrical charge. This characterisitic allows them to disrupt microbial membranes which have a positive charge as well as enveloped viruses. These peptides can affect nonenveloped viruses by blocking viral receptors on the host cell. It is also believed that these peptides can damage bacteria's internal processes such as DNA and protein synthesis. Even though the peptides directly damage the bacteria and alter their internal processes, they are probably more important in boosting the host's immune system. There is a lot of work to be done if we are to harness the power of antimicrobial peptides.

It doesn't matter what type of lab you work in filter paper is part of it. Many manufacturing processes also require filter paper. Filter paper is available as cellulose or glass microfiber. The filter paper grades are determined by the manufacturer. The grade is related to speed or retention size; for instance Whatman 1 filter paper is close to Ahlstom filter paper grade 601. The cellulose filter paper may be qualitative or quantitative(low ash or ashless), wet strengthened, creped, or fluted. For the best filter paper for your application consult Ahlstrom and Whatman(now GE Healthcare) websites.

Glass microfiber filters, GFC, are designed for higher loading, or for gravimetric analyses as they they withstand temperatures up to 550 deg. C. Microfiber filters are best in high loading applications and for pre-filtration prior to using ultrafiltration filters. For guides in determining the best microfiber filter refer to the manufacturer's websites.

The term penicillin refers to a group of over 50 chemically related antibiotics. All penicillins have a common core structure that contains a B-lactam ring called the nucleus. Penicillins differ by the chemical side chains attached to their nuclei. Penicillins can be produced either naturally or synthetically and they prevent the crosslinking of peptidoglycans, which interferes with the construction of the cell wall in gram-positive bacteria. Penicillin extracted from cultures of the mold penicillium exists in several closely related forms known as natural penicillins. Penicillin G has a narrow but useful spectrum of activity and is often the drug of choice against staphylococci, streptococci, and several spirochetes. The effectiveness of penicillin can be seen on agar plates containing bacterial cultures. The body removes penicillin G fairly quickly however when penicillin G is combined with other drugs it can last up to 24 hours in the body. The downside of natural penicillins is that they have a narrow spectrum of activity. Synthetic penicillin can be made by removing side chains from the completed natural molecule and chemically adding a different side chain to make them more resistant.