Biomedical subjects

E Poole

Publications and source records attributed to E Poole.

10 recordsLinked to original sources

PubMed2000

Release factors and their role as decoding proteins: specificity and fidelity for termination of protein synthesis.

The decoding of stop signals in mRNA requires protein release factors. Two classes of factor are found in both prokaryotes and eukaryotes, a decoding factor and a stimulatory recycling factor. These factors form complexes at the active centre of the ribosome and mimic in overall shape the complexes found at other stages of protein synthesis. The decoding release factor is shaped like a tRNA and has a domain for codon recognition at the decoding site of the ribosome, and a domain for peptidyl-tRNA hydrolysis that is inferred to be near the peptidyltransferase centre. Initial interaction of the decoding factor with the ribosome is a low fidelity event involving multiple contacts with the ribosomal components. A subsequent discrimination step, at present poorly defined, ensures high fidelity of codon recognition.

Animals↗

PubMed1999

Temperature-sensitive lesions in two influenza A viruses defective for replicative transcription disrupt RNA binding by the nucleoprotein.

The negative-sense segmented RNA genome of influenza virus is transcribed into capped and polyadenylated mRNAs, as well as full-length replicative intermediates (cRNAs). The mechanism that regulates the two forms of transcription remains unclear, although several lines of evidence imply a role for the viral nucleoprotein (NP). In particular, temperature-shift and biochemical analyses of the temperature-sensitive viruses A/WSN/33 ts56 and A/FPV/Rostock/34/Giessen tsG81 containing point mutations within the NP coding region have indicated specific defects in replicative transcription at the nonpermissive temperature. To identify the functional defect, we introduced the relevant mutations into the NP of influenza virus strain A/PR/8/34. Both mutants were temperature sensitive for influenza virus gene expression in transient-transfection experiments but localized and accumulated normally in transfected cells. Similarly, the mutants retained the ability to self-associate and interact with the virus polymerase complex whether synthesized at the permissive or the nonpermissive temperatures. In contrast, the mutant NPs were defective for RNA binding when expressed at the nonpermissive temperature but not when expressed at 30 degrees C. This suggests that the RNA-binding activity of NP is required for replicative transcription.

Animals↗

PubMed1997

Anti-emetic drug effects on pilot performance: granisetron vs. ondansetron.

BACKGROUND: The objectives of this study were to evaluate the effects of two anti-emetic drugs, granisetron (1 mg tablets/2 mg oral dose) and ondansetron (8 mg tablets/8 mg oral dose) on flying and mission performance in an F-16 research simulator. METHODS: The experimental approach, involving 9 pilots, was a placebo controlled, double blind, crossover design. Each pilot flew three defensive counter air missions. Data on nine measures of flying performance were collected via the simulator data recorder. In addition, ratings on mission and flying performance were recorded by simulator instructor pilots. Data were also collected on symptoms and side effects, mood, and vigilance. RESULTS: This study, carried out in the context of a simulated tactical air-to-air combat mission, produced no significant differences between the effects of the target drugs and placebo on any of the nine objective flying performance measures, including a composite measure of landing performance. There were no differences in evaluator ratings of routine mission flying or air combat performance. Pilots could not distinguish active drug from placebo and there were no differences on any of the mood scales. CONCLUSIONS: These results confirm our earlier findings that the drugs of interest are well tolerated and produce no cognitive, psychomotor or subjective state changes. In this study, there was no evidence of performance degradation caused by either granisetron or ondansetron when tested in a complex, military task environment.

Administration, Oral↗

PubMed1995

Nonfamilial tumoral calcinosis associated with chronic renal failure and secondary hyperparathyroidism: report of two cases with clinicopathological, immunohistochemical, and electron microscopic findings.

The clinical and pathological findings, including those of immunohistochemical and ultrastructural studies, of two cases of tumoral calcinosis-like lesion (TCL) are described. Both cases were associated with chronic renal failure and hyperparathyroidism. One case presented as a rapidly growing 20-cm multiloculated, cystic, calcific gluteal mass on the sacrum, which was not clinically suspected to be related to hyperparathyroidism. The other case presented as a 2.5-cm calcific mass on the right foot that recurred after surgical excision as a 7-cm mass, which was clinically presumed to be related to secondary hyperparathyroidism. Light microscopic and immunohistochemical studies on both cases and ultrastructural studies on one case indicated that the calcifying process involved histiocytes and osteoclast-like giant cells of histiocytic origin lining the cystic cavities. Hydroxyapatite crystal formation and calcification appeared to develop predominantly from intracytoplasmic membrane bound vesicles and also from mitochondria. These findings are similar to those recently reported for familial tumoral calcinosis, which support its having a mechanism of calcification comparable with that of a TCL.

Aged↗

PubMed1992

Chlamydia trachomatis serovar differentiation by direct sequence analysis of the variable segment 4 region of the major outer membrane protein gene.

The polymerase chain reaction method was used to amplify DNA from the fourth variable segment of the gene encoding the major outer membrane protein of Chlamydia trachomatis. Direct sequencing of the amplified DNA from prototype strains confirmed previously identified nucleotide sequence differences that were specific for each serovar. This analysis revealed differences in the DNA sequences of prototype strains C/UW-1 and G/IOL-238 from those of prototype strains C/TW-3 and G/UW-57, sequenced previously. This method was also used to determine the serovar types of C. trachomatis in 125 urogenital specimens from infected patients. The most common serovars were E (38%), F (17%), and G and D (14% each). Serovar D was found significantly more often in specimens from men than in specimens from women (P = 0.004). Conversely, serovar G was found significantly more often in specimens from women than in specimens from men (P = 0.026). Only two serovar G isolates gave sequences identical to that of the prototype strain G/IOL-238, suggesting that this strain may be a serovar variant. Three isolates (D+, G-, and J') gave sequences which have not been reported previously. One isolate had the same sequence as the D- serovar variant. Sequence analysis of amplified DNA reveals subtle differences between C. trachomatis strains and provides a very sensitive method for molecular epidemiological analysis.

Bacterial Outer Membrane Proteins↗

PubMed1987