Biomedical subjects
D M Evans
Publications and source records attributed to D M Evans.
Tumors of the vulva and vagina. Benign cysts and tumors of developmental origin.
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Deinococcus radiodurans UV endonuclease beta DNA incisions do not generate photoreversible thymine residues.
The ability of UV endonuclease beta of Deinococcus radiodurans to act as a pyrimidine dimer DNA glycosylase was investigated. Cell-free extracts of D. radiodurans exhibiting UV endonuclease beta activity failed to generate incisions in irradiated DNA that liberated free-thymine residues upon photoreversal with 254-nm light. This is in marked contrast to the pyrimidine dimer UV glycosylase of Micrococcus luteus that does liberate such residues. The result suggests that UV endonuclease beta incises DNA by true endonuclease action.
Critical role of an eight-amino acid sequence of VP1 in neutralization of poliovirus type 3.
The three serotypes of poliovirus are members of the picornaviradae, a group of viruses which cause a variety of diseases of considerable importance in man and animals. We have previously used antigenic mutants resistant to neutralizing monoclonal antibodies to identify a single antigenic site for the neutralization of poliovirus type 3 (ref. 1). Evidence based on oligonucleotide mapping suggested that this site corresponded largely to one physicochemical region of the capsid protein viral polypeptide 1 (VP1). We now present conclusive evidence that most of the mutations conferring resistance to neutralization are confined to an eight-amino acid region of VP1, specified by a sequence of viral RNA 277-300 bases from the start of the region coding for VP1. These data strongly suggest that this small region constitutes a major antigenic site involved in virus neutralization and they provide the most detailed information currently available on the antigenic site of a human virus.
Increased neurovirulence associated with a single nucleotide change in a noncoding region of the Sabin type 3 poliovaccine genome.
Most of the small number of cases of poliomyelitis which occur in countries where Sabin's attenuated poliovirus vaccines are used are temporally associated with administration of vaccine and involve polioviruses of types 2 and 3 (ref. 1). Recent studies have provided convincing evidence that the Sabin type 2 and 3 viruses themselves may revert to a neurovirulent phenotype on passage in man. We report here that a point mutation in the 5' noncoding region of the genome of the poliovirus type 3 vaccine consistently reverts to wild type in strains isolated from cases of vaccine-associated poliomyelitis. Virus with this change is rapidly selected on passage through the human gastrointestinal tract. The change is associated with a demonstrable increase in the neurovirulence of the virus.
Identification of an antigenic site in the neutralization of type 3 poliovirus.
Antigenic mutants of type 3 poliovirus were obtained by picking plaques formed in the presence of neutralizing monoclonal antibodies. All the mutants were clustered into a single operationally defined antigenic site based on their reactions with a panel of antibodies. Most of the mutations were shown to be located in the virion protein VP1 by sodium dodecyl sulfate-polyacrylamide gel electrophoresis and oligonucleotide mapping, and 15 of 16 mutants had single-point mutations in a region of VP1 encompassing only eight amino acids, a finding suggesting that this is a major target for the neutralization of the virus. Whereas other areas may also be required, it is likely that this region is a necessary component of a vaccine of any kind.
Maximum effect of urokinase plasminogen activator inhibitors in the control of invasion and metastasis of rat mammary cancer.
Experimentally induced pulmonary metastases of mammary cancer in the Fisher 344 rat can be suppressed by the inhibition of urokinase plasminogen activator (uPA). The inhibition of uPA with amiloride or B428 has been shown to be dose dependent. Increased dosage levels of inhibitors might be expected to enhance levels of suppression of metastases. The use of each of these inhibitors at equipotent concentrations that exceeded the doses administered in previous studies failed to eliminate pulmonary metastases. These results demonstrate that a maximum limit is attained for the inhibitory capacities on cells during in vitro invasion or in vivo metastasis. At increased levels, uPA inhibitors continue to suppress, but do not eradicate, experimental pulmonary metastases of MATB cell rat mammary cancer.
Images in cardiovascular medicine. Cantrell's syndrome: left ventricular diverticulum in an adult patient.
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The sites of origin of gastric cancers and ulcers in relation to mucosal junctions and the lesser curvature.
A histological mapping procedure was used to study 32 stomachs bearing small cancers and 23 stomachs bearing ulcers. Over 80 per cent of gastric cancers and peptic ulcers occurred within 2 cm of both a mucosal junction and the lesser curvature. They showed slight differences in their longitudinal relationship to the pyloric junction. There were differential characteristics between the groups of cancers arising at each of the three mucosal junctions. Cancers at the pylorus and cardia were more common in males (M:F--2.6:1) and were predominantly well differentiated, whereas those from the intermediate zone were more common in females (M:F--1:1.8) with a relatively higher proportion of undifferentiated cancers. These and other features suggest that gastric cancers should be subdivided according to the junction of origin.
Ultrasonic dispersal of cervical cell aggregates.
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Symposium on cervical cytology.
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Carbimazole hypersensitivity and liver damage.
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