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Biomedical subjects

J Parker

Publications and source records attributed to J Parker.

At least 271 records · Page 15Linked to original sources
PubMed1984

Control of basal-level codon misreading in Escherichia coli.

Basal-level misreading of asparagine codons was examined in a number of Escherichia coli strains. Lysine substitutions were measured by quantitating the amount of charge heterogeneity in MS2 coat protein. In most strains the heterogeneity was consistent with misreading of AAU codons at a frequency of 3-6 X 10(-3). Strains with streptomycin resistance mutations (rpsL) have reduced levels of misreading. There is no significant difference in the frequency of basal-level errors in stringent (relA+) and relaxed (relA) strains, even during starvation for amino acids unrelated to the substitution being studied.

Amino Acids↗
PubMed1984

Binding of interleukin 2 to gangliosides.

Exogenous gangliosides inhibit interleukin 2 (IL2)-dependent growth of a T cell line, AKIL -1.E8. IL2 activity is retained by columns of ganglioside covalently linked to poly(L-lysine)-agarose and is not eluted with ethylene glycol but is completely recovered by elution with 1% SDS. The ability of gangliosides to inhibit IL2 activity is directly related to the complexity of their carbohydrate portion, and related ceramide derivatives at similar concentrations do not inhibit IL2 activity. We conclude that IL2 bound to exogenous gangliosides is inactive and that the carbohydrate portion of the ganglioside is crucial to its interaction with IL2.

Animals↗
PubMed1984

Codon specificity of starvation induced misreading.

Mistranslated derivatives of the coat protein of the bacteriophage MS2 were isolated from infected cells starved for asparagine. This protein contains a high level of lysine for asparagine substitutions. By peptide analysis and amino acid sequencing we show that there is a six-fold greater frequency of errors at AAU codons than at AAC codons. This ratio is the same as that found in unstarved cells where the overall error frequency is 100-fold less. We also demonstrate that, at least for AAC codons, context affects error frequency.

Amino Acid Sequence↗
PubMed1984

External threat and the definition of deviance.

Research ( Lauderdale , 1976; Schachter , 1951) suggests that an external threat to a group can lead to the rejection of deviant members of the group and alteration of group communication patterns and solidarity. This study sought to extend those findings, integrate them with concepts from Simmel 's (1917/1955) work on group conflict, and link them to key issues in the societal reaction approach to deviant behavior. We examined the effect of variation in level of threat, the relationship between deviant status and nonconformity to the central task norm, the role of high-status actors in deviance designation, the relationship between rejection and negative definition of the deviant, and the effects of rejection and negative definition on group solidarity. Hypotheses were tested in an experimental design involving three conditions (strong threat, weak threat, and no threat). The results suggest that (a) the level of threat is directly related to the extent of rejection and negative definition, (b) nonconformity to the central task norm is not systematically related to deviant status, (c) high-status actors are more involved in the rejection of the deviant, (d) sociometric rejection of the deviant is accompanied by negative definition in the strong-threat condition, and (e) the level of group solidarity is related to the extent of rejection and negative definition. Implications of these findings are discussed relative to the societal reaction approach to deviant behavior and analogous processes in other social groups.

Adolescent↗
PubMed1984

Identification of the purC gene product of Escherichia coli.

The purC region of the Escherichia coli chromosome was isolated from in vivo-derived lambda transducing bacteriophages and cloned in high-copy-number plasmids. The product of the purC gene, phosphoribosylaminoimidazolesuccinocarboxamide synthetase, was identified as a protein with an Mr of ca. 27,000. The level of the protein is increased by more than 60-fold in strains carrying the gene on a high-copy-number plasmid. Purine addition represses the enzyme level in both plasmid- and non-plasmid-containing strains.

Adenine↗
PubMed1984

Cat eye syndrome owing to tetrasomy 22pter leads to q11.

A case of tetrasomy 22pter leads to q11 with ocular hypertelorism, downward slanting palpebral fissures, total anomalous pulmonary venous return, and anal atresia is described. The phenotypic variability of the cat eye syndrome is emphasised along with the need for categorisation of these patients according to well characterised cytogenetic findings.

Abnormalities, Multiple↗
PubMed1984

Maprotiline poisoning: a case of cardiotoxicity and myoclonic seizures.

A 64-year-old man ingested 4500 mg of maprotiline hydrochloride. He developed major motor myoclonic seizures, first-degree AV block, intraventricular conduction delay, hypotension, and urinary retention. Myoclonic seizures have not been previously reported with maprotiline toxicity.

Aged↗
PubMed1983

Codon usage and mistranslation. In vivo basal level misreading of the MS2 coat protein message.

The coat protein of the small RNA virus MS2 shows charge heterogeneity in vivo. In most strains there is a basic satellite of the native protein. We have shown that this basic satellite is greatly diminished or absent in strains with the streptomycin-resistant allele, rpsL, a mutation which leads to increased translational accuracy. Further, the satellite is present in cells where the coat protein is encoded by duplex DNA. Tryptic digests of the satellite show that it contains new lysine-containing peptides which appear to be the same as those found in derivatives of coat protein which have a lysine for asparagine substitution. Sequencing of the NH2-terminal 19 amino acids of the satellite protein shows that the asparagine codon AAU at amino acid 12 is misread approximately 8 times more frequently than the AAC at amino acid 3. We conclude that the satellite species is the result of basal level lysine for asparagine substitution. These substitutions are most likely caused by preferential misreading of AAU codons at a frequency of approximately 5 X 10(-3), 10-fold higher than the average error frequency.

Amino Acid Sequence↗
PubMed1983

The risk of infection related to radial vs femoral sites for arterial catheterization.

To evaluate risk factors for infections associated with indwelling arterial catheters, 186 catheters were randomly allocated for either femoral or radial insertion in 155 critically ill patients. Femoral catheters were easier to insert and it was easier to obtain blood specimens from them. Rates of local infection at the insertion sites and rates of positive catheter-tip cultures were similar for femoral and radial catheters. Evidence of local infection was not predictive of a positive catheter-tip culture. Percutaneously inserted femoral and radial artery catheters had a similarly low incidence of catheter-associated infections. There was only one catheter-related infection, and no cultured catheter was judged the cause of bacteremia. Routine prophylactic replacement of arterial catheter systems may be unnecessary in critical care units where rates of arterial catheter-associated infections are low.

Adult↗