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Biomedical subjects

David Ellis

Publications and source records attributed to David Ellis.

At least 37 records · Page 2Linked to original sources
PubMed2004

Interlaboratory comparison of results of susceptibility testing with caspofungin against Candida and Aspergillus species.

Seventeen laboratories participated in a study of interlaboratory reproducibility with caspofungin microdilution susceptibility testing against panels comprising 30 isolates of Candida spp. and 20 isolates of Aspergillus spp. The laboratories used materials supplied from a single source to determine the influence of growth medium (RPMI 1640 with or without glucose additions and antibiotic medium 3 [AM3]), the same incubation times (24 h and 48 h), and the same end point definition (partial or complete inhibition of growth) for the MIC of caspofungin. All tests were run in duplicate, and end points were determined both spectrophotometrically and visually. The results from almost all of the laboratories for quality control and reference Candida and Aspergillus isolates tested with fluconazole and itraconazole matched the NCCLS published values. However, considerable interlaboratory variability was seen in the results of the caspofungin tests. For Candida spp. the most consistent MIC data were generated with visual "prominent growth reduction" (MIC(2)) end points measured at 24 h in RPMI 1640, where 73.3% of results for the 30 isolates tested fell within a mode +/- one dilution range across all 17 laboratories. MIC(2) at 24 h in RPMI 1640 or AM3 also gave the best interlaboratory separation of Candida isolates of known high and low susceptibility to caspofungin. Reproducibility of MIC data was problematic for caspofungin tests with Aspergillus spp. under all conditions, but the minimal effective concentration end point, defined as the lowest caspofungin concentration yielding conspicuously aberrant hyphal growth, gave excellent reproducibility for data from 14 of the 17 participating laboratories.

Antifungal Agents↗
PubMed2004

What if... [the consequences of innovation].

Innovations that could turn health care upside down are already here, in use or in development. These technological or clinical "wild cards" so resemble science fiction that they are easily dismissed--for example, brain implants to help the disabled control remote appliances or human arteries grown from scratch. Ignore them at your own risk.

Biomedical Technology↗
PubMed2003

Crystal engineering with heteroboranes. III. 2-Carboxy-1-methoxymethyl-1,2-dicarba-closo-dodecaborane(12).

The title compound, 1-CH(2)OCH(3)-2-COOH-1,2-closo-C(2)B(10)H(10) or C(5)H(16)B(10)O(3), forms a discrete centrosymmetric tetramer, via hydrogen bonding, involving two inner and two outer carborane molecules. One conventional eight-membered hydrogen-bonded ring [graph set R(2)(2)(8)] is formed between two carboxylic acid groups of the inner carboranes. This interaction is then supplemented by an open finite hydrogen bond (graph set D) between the ether O atom of the inner carborane and the carboxylic acid H atom of the outer carborane.

Journal Article↗
PubMed2003

Crystal engineering with heteroboranes. II. 1,2-Dicarboxy-1,2-dicarba-closo-dodecaborane(12) ethanol hemisolvate.

The title compound, 1,2-(COOH)(2)-1,2-closo-C(2)B(10)H(10).0.5C(2)H(6)O or C(4)H(12)B(10)O(4).0.5C(2)H(6)O, forms a tetramer by incorporating ethanol (solvent) molecules through hydrogen bonding. Two eight-membered rings [graph set R(2)(2)(8)] are formed by hydrogen bonding between two carboxylic acid groups, whereas two ten-membered rings [R(3)(3)(10)] are formed by hydrogen bonding between two carboxylic acid groups and the OH group of an ethanol molecule (solvent). Two crystallographically independent tetramers are present in the crystal structure.

Journal Article↗
PubMed2003

Prediction of pathogenic mutations in patients with early-onset breast cancer by family history.

We aimed to assess frequency and penetrance of BRCA1, BRCA2,and TP53 mutations in women diagnosed with breast cancer aged 30 years or younger, and then correlate this frequency with family history. 17 of 36 familial cases had a BRCA1, BRCA2, or TP53 mutation, compared with three of 63 non-familial cases. The calculated population frequency of TP53 mutations was one in 5000, substantially greater than previous estimates. This finding underlines the importance of accurate elucidation of a family history from young women diagnosed with breast cancer. Establishment of family history could help with development of patient-specific management and tumour surveillance protocols.

Adult↗
PubMed2003

Pharmacokinetics and pharmacodynamics of intrathecal ziconotide in chronic pain patients.

The pharmacokinetics and pharmacodynamics of ziconotide were assessed over a 48-hour period following intrathecal (i.t.) administration (1, 5, 7.5, or 10 micrograms) to 22 patients with chronic, nonmalignant pain. Plasma and cerebrospinal fluid (CSF) samples were obtained over a 24-hour period. Analgesic efficacy was monitored using Visual Analog Scale of Pain Intensity (VASPI) and Category Pain Relief Scores (CPRS) measurements. Pharmacokinetic (PK) parameters were calculated by noncompartmental methods. Plasma ziconotide data were insufficient for PK calculations. In CSF, the median half-life of ziconotide was 4.5 hours. The median CSF clearance and volume of distribution were 0.26 mL/min and 99 mL, respectively. CSF pharmacokinetics of ziconotide were linear, based on cumulative exposure and peak CSF concentrations. A dose-related analgesia was observed. Pharmacokinetic-pharmacodynamic efficacy and safety analyses showed that higher CSF ziconotide concentrations were generally associated with analgesia and increased incidence of nervous system adverse events following a 1-hour i.t. infusion.

Adult↗
PubMed2002

The first supraicosahedral p-block metallacarboranes.

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.

Journal Article↗
PubMed2002

Amphotericin B: spectrum and resistance.

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.

Amphotericin B↗
PubMed2002

Single-use acupuncture needles: scanning electron-microscopy of needle-tips.

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.

Acupuncture Analgesia↗