Biomedical subjects
Publications and source records attributed to David Ellis.
Reaction of Na2[7,9-C2B10H12] or its C-dimethyl analogue with SnCl2 in THF affords 4,1,6-closo-SnC2B10H12 or 1,6-Me2-4,1,6-closo-SnC2B10H10 respectively, the first 13-vertex metallacarboranes involving p-block metals; spectroscopic, structural and theoretical studies, including an analysis of fluctionality in solution, are reported.
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Amphotericin B is a polyene macrolide antibiotic derived from the actinomycete Streptomyces nodosus. Of the 200 known polyene agents, amphotericin B is the only one with toxicities that are sufficiently limited to permit intravenous administration. All polyenes have a common mechanism of action in that they preferentially bind to ergosterol, the primary sterol in the fungal cell membrane. The consequence of this binding includes disruption of the osmotic integrity of the membrane, with leakage of intracellular potassium and magnesium, and also the disruption of oxidative enzymes in target cells. Amphotericin B has a relatively broad spectrum of action and is useful in treating cases of candidosis, cryptococcosis, histoplasmosis, blastomycosis, paracoccidioidomycosis, coccidioidomycosis, aspergillosis, extracutaneous sporotrichosis and mucormycosis, and some cases of hyalohyphomycosis and phaeohyphomycosis. Resistance (MIC > 2 mg/L) tends to be species-dependent and emerges uncommonly and slowly in isolates from patients treated with amphotericin B. These include some individual strains of Candida albicans, Candida tropicalis, Candida parapsilosis and Candida lusitaniae, which may acquire resistance during treatment. Some isolates of Scedosporium apiospermum, Fusarium spp. and Sporothrix schenckii also show primary resistance, whereas all strains of Scedosporium prolificans demonstrate resistance. The main problems associated with the use of conventional amphotericin B have always been due to its poor aqueous solubility and toxicity rather than antifungal resistance.
Unselected, disposable acupuncture needles from various manufacturers and retail suppliers were taken from a pool of donated and bought samples. Three needles of each type were prepared for electron-microscopy. The needle tips were inspected at two magnifications (x39.37 and x612.5): 52 electron-micrographs were taken of 31 individual needles from 11 different types. No needle-tip looked perfect and significant faults were seen in most; some appeared seriously deformed. The faults noted were: scratch marks along or across the needle, metallic scuff, lumps and irregularities in the needle surface, needle-tip stubbed or malformed, and needle point off-centre. An additional test made was to wipe a number of needles firmly on white paper tissue. Some left grey lines, and these were regarded as evidence of metallic or oily residue from the needle surface which could have been deposited in the patient. These unexpected findings, in a variety of popularly used needles from well-respected suppliers, suggest that most manufacturers need to reassess their quality control procedures.