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Biomedical subjects

H M Lewis

Publications and source records attributed to H M Lewis.

51 records · Page 3Linked to original sources
PubMed1983

The pyruvate dehydrogenase complex of Escherichia coli K12. Nucleotide sequence encoding the dihydrolipoamide acetyltransferase component.

The nucleotide sequence of the aceF gene, which encodes the dihydrolipoamide acetyltransferase component (E2) of the pyruvate dehydrogenase complex of Escherichia coli K12, has been determined using the dideoxy chain-termination method. The aceF gene comprises 1887 base pairs (629 codons excluding the initiation codon AUG); it is preceded by a short intercistronic segment of 14 base pairs containing a good ribosomal binding site, and it is followed closely by a potential rho-independent terminator. The results extend by 1980 base pairs the previously sequenced segment of 3780 base pairs containing the structural gene (aceE) of the pyruvate dehydrogenase component (E1) and they confirm that aceE and aceF are the proximal and distal genes of the ace operon. The amino terminus, carboxy-terminal sequence and amino acid composition of the acetyltransferase subunit predicted from the nucleotide sequence are in excellent agreement with previous studies with the purified protein. The predicted molecular weight (Mr = 65959) confirms experimental values derived from sedimentation equilibrium analysis and indicates that the higher values (78000-89000) that have been reported are due to unusual features of the protein that lead to anomalous mobilities during sodium dodecyl sulphate/polyacrylamide gel electrophoresis and in gel filtration. The primary structure fully supports conclusions, based on limited tryptic proteolysis, that the acetyltransferase subunit possesses two heterologous domains: the lipoyl domain and the subunit binding and catalytic domain. The lipoyl domain corresponds to the amino-terminal segment of the protein. It is acidic and contains three remarkably homologous repeating units of approximately 100 amino acids, each possessing a potential lipoyl binding site and a region that is characteristically rich in alanine and proline residues. The subunit binding and catalytic domain occupies most of the residual polypeptide in the carboxy-terminal segment.

Acetyltransferases↗
PubMed1983

The pyruvate dehydrogenase complex of Escherichia coli K12. Nucleotide sequence encoding the pyruvate dehydrogenase component.

The nucleotide sequence of a 3780-base-pair segment of DNA containing the aceE gene encoding the pyruvate dehydrogenase component (E1) of the pyruvate dehydrogenase complex of Escherichia coli, has been determined by the dideoxy chain-termination method. The aceE structural gene comprises 2655 base pairs (885 codons, excluding the initiation codon AUG), it is preceded by a good ribosome binding site and several potential RNA polymerase binding sites. Its polarity and location in the restriction map of the corresponding segment of DNA are consistent with it being the proximal gene in the ace operon, as defined in previous genetic and post-infection labelling studies. The relative molecular mass (99474), composition (885 amino acids), amino-terminal residue and carboxy-terminal sequence predicted from the nucleotide sequence are in excellent agreement with published information obtained from studies with the purified pyruvate dehydrogenase component (E1). The nucleotide sequence also contains a second gene (gene A) situated upstream of the aceE gene. It appears to be an independent gene containing 708 base pairs (236 codons) and encoding a weakly expressed product (protein A; Mr = 27049) of unknown function.

Amino Acids↗
PubMed1982

Use or abuse of phototherapy for physiological jaundice of newborn infants.

To investigate the need for and effects of phototherapy in full-term otherwise healthy babies with physiological jaundice, 40 consecutive babies with serum bilirubin levels of 250 mumol/l or more were assigned at random to two treatment groups. Phototherapy was started in the early group (n = 20) when serum bilirubin was 250 mumol/l and in the late group (n = 20) when serum bilirubin reached 320 mumol/l; however, only 3 of the late group required treatment. Phototherapy prevented a further rise in bilirubin in almost all treated babies, but the difference in peak bilirubin level between early and late treatment groups was not significant. Early phototherapy produced a more rapid decline in bilirubin; levels fell to below 250 mumol/l in a median of 28 h with early treatment and 54 h with late treatment. In each group the ratio of boys to girls was 2/1 and boys remained jaundiced for significantly longer. Phototherapy therefore curtailed the rise and duration of hyperbilirubinaemia, but the effect was small. Jaundice subsided spontaneously in most of these mature infants, especially girls. Phototherapy can separate mother from baby, and it is physiologically stressful. Treatment may be safely withheld until serum bilirubin exceeds 320 mumol/l.

Bilirubin↗
PubMed1980

The complete amino acid sequence of human fibroblast interferon as deduced using synthetic oligodeoxyribonucleotide primers of reverse transcriptase.

Using synthetic oligodeoxyribonucleotides to prime the transcription of interferon mRNA and cDNA, we recently determined the mRNA sequence coding for the 47 amino-terminal amino acids of mature human fibroblast interferon (1). From this sequence, we have now synthesised an oligodeoxyribonucleotide that is homologous with the mRNA sequence coding for amino acids 42-45 and used it as a primer to selectively transcribe an interferon cDNA template. The sequence of the newly synthesised DNA predicted the sequence of amino acids 48-109 in the interferon polypeptide. By repeating this process with one more primer, we have determined the complete amino acid sequence of mature human fibroblast interferon, a polypeptide of 166 amino acids.

Amino Acid Sequence↗
PubMed1980

The amino-terminal sequence of human fibroblast interferon as deduced from reverse transcripts obtained using synthetic oligonucleotide primers.

From recently published data on the amino-terminal structures of human and mouse interferons, we have predicted and synthesised an oligonucleotide capable of priming specifically the reverse transcription of human fibroblast interferon mRNA present within a total mRNA population. From these transcripts we determined the sequence of the 5'-terminus of the mRNA and identified a putative pre-peptide signal sequence. This enabled us to predict the sequence of another primer capable of directing the synthesis of interferon double-stranded cDNA corresponding to the entire coding region of the mRNA. Further sequencing studies also enabled us to establish the identity of 47 consecutive amino acids beginning with the methionine residue at the amino-terminus of the mature protein.

Amino Acid Sequence↗
PubMed1979

Role of viruses in febrile convulsions.

A disseminated viral illness was demonstrated by isolating a virus from the CSF, blood or urine in 27% of 73 children who were admitted to hospital after a first febrile convulsion. However, a viral aetiology could be implicated for 86% of the children after combining results of tissue culture, electron microscopy, mouse inoculation, complement fixation tests, and interferon assay. Parallel bacterial cultures showed a possible pathogen in 29% of children, but in only 4% was the pathogen isolated from the CSF, blood, or urine. No correlation was found between the nature of the pathogen (or evidence of its dissemination) and the severity of the convulsion, degree of fever, CSF protein, CSF white cells, or the WBC. The results suggest that a febrile convulsion could be a response to invasion of the blood stream or central nervous system by a micro-organism which is usually a virus. Invasion may be of such brief duration that successful isolation of the virus from the blood, CSF, or urine in not more commonly achieved.

Child↗
PubMed1979

A year's experience of the rotavirus syndrome and its association with respiratory illness.

In a hospital study rotavirus was identified in 51% of 152 children with diarrhoea. These patients showed a clinical pattern that was distinct from patients in whom the diarrhoea was associated with bacteria, other viruses, or no pathogens. A respiratory illness was described in 66% of rotavirus patients and usually preceded the gastrointestinal symptoms. Vomiting lasted between one and 3 days and was curtailed by substituting the normal diet with clear fluids. Watery diarrhoes continued for 4 or 5 days, even when rehydration was by the intravenous rather than the oral route. Prolonged diarrhoea was rare. Most children infected with rotavirus were under 2 years of age, but dehydration was most severe in infants aged between 12 and 18 months. A clinician can thus recognise the rotavirus syndrome and expect spontaneous recovery if adequate rehydration is maintained for a critical few days.

Adolescent↗
PubMed1976

Erosive adenomatosis of the nipple.

Erosive adenomatosis of the nipple is a rare, usually benign neoplasm of the major nipple ducts. Although morphologic features may distinguish it from Paget disease, histopathological differentiation is simple. Recognition of this tumor may spare needless mastectomy.

Adenoma↗