Biomedical subjects
Publications and source records attributed to D Riley.
Seventy-one Geomedic total knee replacements were reviewed retrospectively at a maximum of eight and a half years. The prosthesis was found to be successful in its primary aim of relieving pain. However, there was an overall failure rate of 18.3%. Analysis of the results by an actuarial method allowed comparison with other prostheses. The factors involved in failure are discussed.
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36 young adult volunteers were given either virus, or inactivated surface-antigen influenza vaccine, containing influenza A (H1N1) antigen. Their peripheral-blood lymphocytes were analysed to determine whether cytotoxic T lymphocytes (CTL) were induced by these vaccines. All three vaccines induced HLA-restricted T-lymphocyte responses specific for influenza A virus. This CTL response was found in 28 of 30 volunteers who showed antibody responses and in 3 of 6 who did not develop antibodies. Virus infected target cells showing certain HLA antigens (A1, A9, and B8) were less susceptible to lysis by HLA-matched cytotoxic T effector cells than target cells which matched effectors at other HLA loci.
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Recent observations suggest that the basic supranucleosomal structure of chromatin is a zigzag helical ribbon with a repeat unit made of two nucleosomes connected by a relaxed spacer DNA. A remarkable feature of one particular ribbon is that it solves the apparent paradox between the number of DNA turns per nucleosome and the total linking number of a nucleosome-containing closed circular DNA molecule. We show here that the repeat unit of the proposed structure, which contains two nucleosomes with -1 3/4 DNA turns per nucleosome and one spacer crossover per repeat, contributes -2 to the linking number of closed circular DNA. Space-filling models show that the cylindrical 250-A chromatin fiber can be generated by twisting the ribbon.
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Long stretches of protein-free, nonbeaded DNA were observed electron microscopically in nuclear spreads prepared from cells that had replicated their DNA in the absence of protein synthesis. The amount of this DNA increased with increasing time of replication in the presence of cycloheximide and was greatly decreased when replication was inhibited with 1-beta-D-arabinofuranosylcytosine (cytosine arabinoside). This DNA is considered to be "free" DNA because it has the same diameter as marker PM2 DNA and it is preferentially sensitive to DNase I digestion. Reversal of the cycloheximide block resulted in a burst of histone synthesis and repair of the depleted chromatin within 5 min. In addition, 26 presumptive replication forks were observed with beaded chromatin on two arms and free DNA on the third. These results suggest that new histones are usually deposited onto new DNA, that the cellular histone pool is very small, that histone migration is minimal in vivo for at least 18 hr, that for most fibers nuclesome assembly and segregation is conservative for stretches of DNA as long as 100 kbases, and that some part of the octameric histone core may remain bound to DNA during the replication process. The regularity we have observed for the assembly and segregation of nucleosomes is likely to be important for our understanding of how chromosomal information is segregated during development.
Nucleosomes were treated with increasing concentrations of exonuclease III (Exo III) from E. coli. At low levels of Exo III, the heterogeneous distribution of monomers (with associated DNA fragments ranging in size between 140 and 170 bp) is "trimmed" down to a discrete core of 140 bp. The "trimming" of monomers to 140 bp results from a 3' exonucleolytic digestion accompanied by a 5' clipping activity which is specific for the conformation of internucleosomal DNA. At higher concentrations of Exo III, the enzyme digests the 140 bp "trimmed" nucleosome core from both 3' ends without associated 5' nuclease activity. Most striking is the observation that the fragments produced during such a digestion display discrete single-stranded lengths that are integer multiples of 10 bases. For some dimer nucleosomes, Exo III can digest as many as 200 bases from at least one 3' end and produce a 10 base interval ladder from about 400 bases down to 180 bases. This suggests that the enzyme can traverse the length of an entire nucleosome without destroying whatever structural features are necessary to produce a 10 base DNA ladder.
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CONTEXT: A zinc preparation that provides a higher concentration of solubilized zinc in a minimally irritating formulation allowing controlled absorption would be of great clinical value for treating oral herpes. OBJECTIVE: To determine the effect of zinc oxide/glycine cream as a treatment for facial and circumoral herpes infection by measuring duration and intensity of signs and symptoms and assessing adverse effects. DESIGN: Double-blind, placebo-controlled, randomized clinical trial. SETTING: Subjects were enrolled from the general community through advertisements. PATIENTS: Forty-six subjects with facial or circumoral herpes infections. INTERVENTION: Application of a zinc oxide/glycine cream or a placebo cream every 2 hours until cold sore resolved or 21 days elapsed. MAIN OUTCOME MEASURES: Duration of cold sore lesions, severity of signs and symptoms, and frequency of adverse effects. RESULTS: Subjects who began treatment with a zinc oxide/glycine cream within 24 hours of onset of signs and symptoms experienced a significantly shorter duration of cold sore lesions (mean, 5.0 days) than did subjects treated with a placebo cream (mean, 6.5 days). Subjects treated with the zinc oxide/glycine cream also experienced reduction in overall severity of signs and symptoms, particularly blistering, soreness, itching, and tingling. Side effects among subjects treated with zinc oxide/glycine cream were those expected from an ionic zinc salt solution. All were completely reversible and of short duration. CONCLUSION: Zinc oxide/glycine cream is an effective treatment for facial and circumoral herpes infection with predictable adverse effects that are completely reversible.
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