Biomedical subjects

Colin Charnock

Publications and source records attributed to Colin Charnock.

8 recordsLinked to original sources

PubMed2006

Synthesis of indolizine derivatives with selective antibacterial activity against Mycobacterium tuberculosis.

1-substituted indolizines with activity against Mycobacterium tuberculosis have been synthesized. The most active compounds carry an hydroxyphenylmethyl- or hydroxyalkyl substituent in the indolizine 1-position. The alkyl chain should be moderately long (C-5 or C-6). Aryl groups in the 2- and 3-position of the indolizine are also required. Removal of the 3-substituent resulted in significant loss of activity. A nitrile substituent in the 7-position is beneficial for both chemical stability and bioactivity. The compounds studied display a narrow antibacterial spectrum and appear to be quite selective antimycobacterial compounds. Moderate activity against certain pathogenic protozoa was also observed.

Animals↗

PubMed2006

Biocidal activity of a bioactive glass-protected, preservative-free tattooing solution.

BACKGROUND: The number of people obtaining a tattoo has increased markedly in recent years Tattooing is known to present a risk of transfer of bacterial/fungal pathogens and possibly also viral pathogens. Colorants used for tattooing purposes can be heavily contaminated with bacteria, thus presenting a risk for infections. Concerted efforts are being made to remove this threat, including the production and use of cleaner dyes and pigments with enhanced antimicrobial properties. METHODS: Challenge tests were used to assess the survival characteristics of bacteria, bacterial endospores, fungal hyphae/spores, and bacteriophage in tattooing colorants. RESULTS: Bacteria were able to grow to high numbers in some colorants. A recently marketed, preservative-free colorant was shown to have a good hygienic quality and rapidly inactivated added bacteria and fungal spores. Activity against bacterial endospores was also demonstrated. Bacteriophage survived in the product during the 28-day test period. CONCLUSION: The present study is the first to document the survival characteristics of vegetative bacteria and endospores, fungi, and bacteriophage (as virus surrogate) in tattooing solutions. The results of the present study readily explain the previously reported high numbers of bacteria in some tattooing colorants. A preservative-free colorant, which was designed in response to recent recommendations of the European Council with respect to chemical content, was also adequately self-preserving with respect to bacterial and fungal growth.

Anti-Infective Agents↗

PubMed2006

(+)-agelasine D: improved synthesis and evaluation of antibacterial and cytotoxic activities.

An improved synthesis of (+)-agelasine D (10) from (+)-manool is reported together with cytotoxic and antibacterial data for agelasine D and structurally close synthetic analogues. These compounds display a broad spectrum of antibacterial activities including effects on M. tuberculosis and Gram-positive and Gram-negative bacteria (both aerobes and anaerobes). They exhibit profound cytotoxic activity against several cancer cells, including a multidrug-resistant cell line. (+)-Agelasine D (10) has been isolated earlier from a marine sponge (Agelas sp.).

Animals↗

PubMed2006

Are multidose over-the-counter artificial tears adequately preserved?

PURPOSE: To investigate artificial tears containing different preservatives for antimicrobial efficacy. Based on the challenge test outlined in the European Pharmacopoeia, products were tested in their original containers to see whether their component preservative had sufficient activity. METHODS: Five brands of over-the-counter artificial tears each containing different preservatives (benzalkonium chloride/EDTA, parabens, chlorobutanol, silver chloride complex, and Purite-stabilized oxychloro complex) were inoculated with test microorganisms (Pseudomonas aeruginosa, Staphylococcus aureus, and Candida albicans). Changes in the microbial start concentration with time were followed by plating onto growth media to provide a measure of the preservative efficacy. In another test, artificial tears were applied to paper disks that were then placed onto agar growth media seeded with microorganisms. Zones of inhibition were measured after incubation. RESULTS: Only the brand of artificial tears containing benzalkonium chloride/EDTA satisfied the major criteria for antimicrobial preservation for all the test microorganisms. Only a benzalkonium chloride/EDTA-containing disk placed on agar seeded with S. aureus produced a zone of inhibition in the agar diffusion test. CONCLUSION: The brand of artificial tears containing benzalkonium chloride/EDTA is suitable for sale in countries adopting the monographs of the European Pharmacopoeia. Other brands would only be suitable for sale if justified reasons for not meeting the major criteria for preservative efficacy can be provided.

Benzalkonium Compounds↗

PubMed2005

Swabbing of waiting room magazines reveals only low levels of bacterial contamination.

Previous studies have shown that toys in waiting rooms of general practice surgeries can be contaminated with potentially pathogenic bacteria. The question was raised as to whether magazines might also be sources of contamination. Swabbing of the front page of 15 magazines from 11 general practice surgeries, followed by analysis for total and specific bacteria, revealed low levels of contamination. Among targeted groups of pathogens only two colonies of Staphylococcus aureus were detected. Magazines do not seem to be potentially important vectors of bacterial transfer in the setting examined.

Bacteria↗

PubMed2005

Dirty magazines.

Explore the source record for details and available documents.

Humans↗

PubMed2004

[Tattooing dyes and pigments contaminated with bacteria].

BACKGROUND: Obtaining a tattoo has become increasingly popular in recent years. However, the degree to which tattooing represents a health risk in the form of infections is still a matter of debate. The aim of the present study was to investigate the microbial content of tattooing dyes and pigments (colourants). MATERIAL AND METHODS: Microbes present in colourants used for tattooing were counted and identified using standard techniques and rapid identification systems. RESULTS: Seven of in total twelve colourants contributed by five studios contained bacteria. No fungi were found. Three solutions contained more than 10 8 bacteria/ml, chiefly aerobic, Gram-negative rods including Pseudomonas aeruginosa. No primary pathogens were found, however, the high colony counts found for some samples may represent infectious doses of a wide range of bacteria. INTERPRETATION: Although required by current regulations to be sterile, a number of colourants were highly contaminated with bacteria. The detection of bacteria in colourants necessitates a review of the studios' internal control procedures. In addition, the appropriate monitoring body should initiate testing of colourants in order to ascertain if these are contaminated at the time of purchase, or become so during use.

Bacteria↗

PubMed2004

Evaluation of the antibacterial efficacy of diesters of azelaic acid.

A number of diesters of the topical dermatosis treatment azelaic (nonanedioic) acid were prepared and tested for antibacterial effect. Two esters, bis-[(hexanoyloxy)methyl] nonanedioate and especially bis-[(butanoyloxy)methyl] nonanedioate showed promising activity against acne related bacteria in vitro. No activity of azelaic acid was detected in Mueller Hinton II agar at pH 7.3 when using the agar diffusion method, whereas both esters gave zones of growth inhibition. At pH 5.6, activity of azelaic acid was detected. At this pH, the zones of inhibition and MIC values obtained with azelaic acid were smaller than those of bis-[(butanoyloxy)methyl] nonanedioate for all test organisms. A preparation for topical use containing 20% (w/w) bis-[(butanoyloxy)methyl] nonanedioate, and the commercially available Skinoren (20% (w/w) azelaic acid), were compared for antibacterial effect against cutaneous bacteria using contact plate analyses of the skin. Though Skinoren was usually most effective, the differences were not statistically significant. Furthermore, bacteria surviving contact with the topical preparations were invariably more sensitive to the ester than to azelaic acid upon subculturing onto agar (pH 5.6) containing either preparation at 0.2-0.7 mg/ml. This might indicate that other factors, such as the composition of the cream base, mitigate the antibacterial activity of the ester. It is proposed that the pharmacological and microbiological properties of bis-[(butanoyloxy)methyl] nonanedioate are worthy of further study based on an extended screening of acne sufferers.

Anti-Bacterial Agents↗