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Biomedical subjects

D J Stevens

Publications and source records attributed to D J Stevens.

At least 19 recordsLinked to original sources
PubMed1995

Genomic structure and sequence of the Fugu rubripes glucose-6-phosphate dehydrogenase gene (G6PD).

To investigate the organization of the compact genome of the puffer fish Fugu rubripes at the level of an individual housekeeping gene, we have cloned and sequenced the glucose-6-phosphate dehydrogenase (G6PD) gene from this fish and compared it to the corresponding human gene. The intron/exon structure of the two genes is identical throughout the protein coding regions. The puffer fish gene is four times smaller than the human gene--the difference is accounted for by the fact that the puffer fish gene has smaller introns. Intron 2 is the largest intron in both species. We have constructed a molecular phylogeny for 10 G6PD protein sequences. The sequences fall in the expected arrangement based on established phylogenetic relationships, with the Plasmodium falciparum sequence the most widely diverged.

Amino Acid Sequence↗
PubMed1995

New glucose-6-phosphate dehydrogenase mutations associated with chronic anemia.

We have identified the glucose-6-phosphate dehydrogenase mutations responsible for enzyme deficiency in nine individuals with chronic nonspherocytic hemolytic anemia. We found the variants Tokyo, Iowa, Shinshu, and Guadalajara in British subjects and Kobe in an Italian. In addition we have determined the variant Corum has the mutation 820 G-->A and have found in British subjects the mis-sense mutations 224 T-->C, 488 G-->A and 833 C-->T which have not been described before. Some, but not all, of the mutations involve amino acids located near putative substrate binding sites.

Anemia, Hemolytic↗
PubMed1989

Acinous cell carcinoma of the larynx.

Acinous cell tumours of the larynx and trachea are extremely rare. A recent review of the literature has only found four reported cases. This short report describes such a patient and discusses her management in the light of previous articles. In view of its rarity in the laryngotracheal area and the uncertainty in the way in which the tumour should be managed, we thought the following case report and review of the literature would be of interest.

Carcinoma↗
PubMed1989

Carcinoma of the pharyngeal pouch.

The condition of carcinoma arising in a pharyngeal pouch is rare. It has been described in relation to long standing pouches and in pouches previously treated by the Dohlman's operation. Three additional cases of carcinoma of the pharyngeal pouch are described.

Aged↗
PubMed1988

Neurofibromas of the paranasal sinuses.

Two cases of neurofibroma of the paranasal sinuses are presented. The tumours presented as space-occupying lesions and were treated by local excision. Histologically one was a typical neurofibroma, whilst the other showed some features of a schwannoma. The patients show no evidence of tumour recurrence at 18 and 6 months respectively.

Adult↗
PubMed1988

Papillary endothelial hyperplasia in the nose.

Benign papillary endothelial hyperplasia is a very rare lesion of the nasal cavity; histologically, it may be mistaken for an angiosarcoma. An awareness of this and the ways in which it differs from angiosarcoma will prevent incorrect diagnosis and inappropriate treatment by surgery or radiotherapy. A case report of each condition involving the nasal cavity is presented.

Adult↗
PubMed1988

Tracheostomy service for ITU patients.

An account of experience of tracheostomy performed on patients in the intensive care unit situation is presented. Forty-seven operations were undertaken over a 5-year period and the advantages and disadvantages are discussed. The authors recommend tracheostomy under these circumstances as an acceptable alternative to the procedure performed in an operating theatre.

England↗
PubMed1987

Antigenic and amino acid sequence analysis of the variants of H1N1 influenza virus in 1986.

Since their reintroduction to human populations in 1977, influenza A viruses of the H1N1 subtype have undergone antigenic drift. Recently a distinct antigenic variant, A/Singapore/6/86, has been almost exclusively isolated internationally, and the antigenic properties and amino acid sequence of its haemagglutinin have been determined and compared with those of the haemagglutinins of other H1N1 viruses, in particular A/Chile/1/83. Fourteen amino acid sequence differences are detected between the HA1 components of these two viruses, ten of which are different from equivalent residues in the haemagglutinins of all H1N1 viruses isolated between 1982 and 1983, and seven of which are novel in the haemagglutinins of all H1N1 viruses sequenced to date. The results are discussed in relation to the three-dimensional structure of the haemagglutinin and the location of the previously defined antigenically important regions.

Amino Acid Sequence↗
PubMed1984

A carbohydrate side chain on hemagglutinins of Hong Kong influenza viruses inhibits recognition by a monoclonal antibody.

A single amino acid substitution, Asp-63 to Asn-63, was detected in the hemagglutinin of an antigenic variant of the 1968 Hong Kong (H3) influenza virus that was selected by growth of the wild-type virus in the presence of a monoclonal antibody. The mutation generates an oligosaccharide attachment site, Asn-Cys-Thr at residues 63-65, that is glycosylated. Immunoprecipitation experiments with extracts from variant virus-infected cells prepared in the presence or absence of tunicamycin, which inhibits glycosylation, demonstrate that addition of the new oligosaccharide side chain is required to prevent reaction with the monoclonal antibody. Similar experiments with the virus of the 1969 Hong Kong influenza epidemic, A/England/878/69, which also contains a hemagglutinin glycosylated at residue 63, support this conclusion and provide evidence for the epidemiological significance of carbohydrate-mediated modifications of hemagglutinin antigenicity.

Amino Acid Sequence↗
PubMed1980

Studies on the quaternary structure of Escherichia coli pyruvate oxidase.

Pyruvate oxidase is a peripheral membrane enzyme isolated from Escherichia coli. The enzyme catalyzes the oxidative decarboxylation of pyruvate to yield acetate plus CO2. The specific activity of the purified oxidase is stimulated 25-fold by lipids, and this lipid requirement has been the subject of previous studies. Since the enzyme is a tetramer at high protein concentrations (1 mg/ml) and is known to self-aggregate under certain conditions, the question arose as to whether the lipid stimulation observed in the steady state assay might be due to a change in the quaternary structure of the protein, either a dissociation or further association. This report is directed at determining the state of association of pyruvate oxidase under assay conditions by using fluorescence polarization. A photoreactive, nonspecific probe, 1-azidonaphthalene 5-sulfonate, was used to label the protein surface with an extrinsic fluorophore. It is concluded that under steady state assay conditions the oxidase remains tetrameric.

Azides↗
PubMed1980

Platelet lesion of collection.

In the early stages of blood collection for transfusion, whole blood is subjected to trauma from the anticoagulant. The blood--anticoagulant mixture does not attain a pH at which platelets can remain functional (approximately pH 6.0) until about 25% of the unit has been collected. We have examined platelet ultrastructure and in vitro aggregation responses to adenosine diphosphate (ADP) and epinephrine (EPN), to assess the platelet trauma of collection into citrate-phosphate-dextrose. For comparison blood was collected by 2 methods: one was conventional (CC), the other metered anticoagulant into the blood as it was collected (MC). Platelets from CC blood showed disruption of organelles and depletion of the dense bodies, whereas platelets from MC blood showed no ultrastructural damage. In addition, biphasic aggregation in response to ADP or EPN was seen in MC platelets but not in CC platelets.

Adenosine Diphosphate↗