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Biomedical subjects

J D Williamson

Publications and source records attributed to J D Williamson.

At least 73 records · Page 4Linked to original sources
PubMed1984

Arginine metabolism in infected cell cultures as a marker character for the differentiation of orthopoxviruses.

Arginine has been shown to be essential for the replication of several orthopoxviruses in mouse sarcoma 180 cells and in chick embryo fibroblast cultures. Both host systems are characterized by their inabilities to utilize citrulline for the biosynthesis of arginine due to deficiencies in the requisite cellular enzymes and cell multiplication is absolutely dependent on the availability of exogenous arginine. Virus replication in such cells maintained with citrulline results from the induction of virus-specific enzymes. Significant virus yields in the absence of exogenous arginine or citrulline can arise from the replenishment of intracellular amino acid pools by increased utilization of arginyl residues in cellular proteins. The extent of the phenotypic expression of these characters in infected cells permitted significant discrimination between the viruses examined. Distinctions could be drawn between rabbitpox, ectromelia, cowpox, buffalopox and vaccinia strains. However, cowpox could not be distinguished from other viruses isolated from diseased animals in European zoos.

Animals↗
PubMed1982

Arginine deprivation and the generation of white variants in cowpox virus-infected cell cultures.

The white pock variant of cowpox virus shows limited growth in chick embryo fibroblasts maintained in arginine-deprived culture medium. Since these conditions inhibit the growth of parental virus, there is a marked increase in the frequency of the white variant in the virus population recovered after passage in the absence of arginine. The variants generated in this system have been characterized by restriction endonuclease analysis of virus DNA in the total DNA recovered from infected cell cultures. Such analysis shows that the white variants arise as deletion mutants of the parental virus, but there was considerable heterogeneity in the restriction patterns of different isolates examined shortly after their generation. Further passage selected white cowpox virus populations with a stable genome configuration comparable with the DNA of pock-purified white variants.

Animals↗
PubMed1980

Polyamine metabolism in MRC-5 cells infected with human cytomegalovirus.

The rate of putrescine uptake into MRC-5 cells increased markedly following infection with human cytomegalovirus (HCMV). Enhanced incorporation occurred immediately after infection and the highest levels were attained following the production of infectious, progeny virus. Parallel kinetic changes in the utilization of radio-labelled putrescine were shown by the amounts of spermidine and spermine recovered from infected cells as radioactive derivatives. A temporal correlation was found between these changes in polyamine metabolism and the synthesis of virus DNA. Methylglyoxalbis(guanylhydrazone), an inhibitor of spermidine and spermine synthesis, did not affect virus replication if HCMV-infected cells were exposed to the inhibitor after completion of the eclipse phase of the virus growth cycle. These results show that polyamine metabolism is required only during the initial stages of HCMV replication.

Biological Transport↗
PubMed1977

Healthward care.

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Allied Health Personnel↗
PubMed1977

Digoxin measurements in general practice.

1 As part of a prospective study on the use of digoxin in a general practice, plasma digoxin concentrations were measured in all patients receiving the drug. 2 A low mean plasma digoxin concentration was observed, suggesting a cautious approach to digitalization. 3 The correlation between plasma digoxin concentration and signs or symptoms commonly used in the assessment of digoxin effect was poor. 4 It was concluded that the measurement of plasma digoxin could be of assistance in a variety of clinical settings within a general practice.

Aged↗
PubMed1977

A conversion code from the RCGP to the ICHPPC classification system.

Faculty members from four family medicine training programs participated in the production of a definitive conversion of the Royal College of General Practitioners Classification of Diseases as modified for use with problem-oriented medical records (RCGP) to the International Classification of Health Problems for Primary Care (ICHPPC). The method used to produce the conversion and the several problems encountered are described. A detailed translation with the appropriate ICHPPC equivalent for each RCGP diagnostic title and code number is provided.

Disease↗
PubMed1976

The effect of canaline on some events in vaccinia virus replication.

Canaline, a pyridoxal phosphate antagonist, is shown to inhibit two distinct events in the replication of vaccinia virus in HeLa cells. Initial events proceed in the presence of the inhibitor leading to the formation of DNA-containing, cytoplasmic inclusions. However, further DNA synthesis is required for the subsequent production of infectious progeny following the reversal of canaline inhibition by pyridoxal phosphate. Inhibition of a separate, maturation event is shown by the delayed addition of canaline resulting in the failure to coat virus-specific DNA synthesized previously in the absence of the inhibitor. Thus, the replication of vaccinia virus is sensitive to inhibition by canaline at an early and a late stage in the replication cycle. Reversal is accomplished alternatively by the addition of 'non-essential' amino acids suggesting that the effects of canaline result from inhibition of specific protein functions.

Amino Acids↗