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Biomedical subjects

E B Hansen

Publications and source records attributed to E B Hansen.

At least 55 records · Page 3Linked to original sources
PubMed1985

Analysis of D-penicillamine by gas chromatography utilizing nitrogen--phosphorus detection.

A method is presented for the analysis of the "orphan" drug D-penicillamine (D-Pa), which is used for the treatment of the inherited rare copper metabolism dysfunction known as Wilson's disease, by assaying a derivative of the compound by gas chromatography employing a rubidium sensitized nitrogen--phosphorus detector. Analytical procedures are described for the analyses of residues of D-Pa X HCl salt in animal feed and for the analyses of the salt or free base from aqueous solutions by utilizing a single-step double derivatization with diazomethane--acetone. Stability data for D-Pa X HCl in animal feed and for the free base in water are presented. An ancillary fluorescence derivatization procedure for the analysis of D-Pa in water is also reported.

Animal Feed↗
PubMed1985

Physical mapping and nucleotide sequence of the rnpA gene that encodes the protein component of ribonuclease P in Escherichia coli.

The rnpA gene, coding for the protein component of ribonuclease P (RNase P), was allocated to the dnaA region at 83 min of the E. coli K-12 map. This was accomplished through analysis of recombinant pBR322 plasmids, some of which complemented the temperature sensitivity of a strain carrying the rnpA 49 allele and restored the RNA processing activity. Although the temperature sensitivity of a strain carrying the rnp-241 allele could not be complemented by the rnpA+ plasmid, the RNA-processing activity was restored, suggesting that the rnp-241 mutation is allelic with rnpA 49. In this analysis we also found two genes coding for proteins (60 and 50 kDal) of unknown function. The order of the genes located in this region is in the clockwise orientation: rpmH (5.4 kDal; ribosomal protein L34), rnpA (14 kDal; protein component of RNase P), a gene for a 60-kDal protein (inner membrane protein), a gene for a 50-kDal protein, and tnaA. All these genes are expressed in the clockwise orientation. From the DNA sequence of the rnpA gene region a very basic polypeptide with an Mr of 13773 could be deduced. We conclude that this polypeptide is the rnpA gene product, and is the protein component of RNase P. Comparison with previously published data on the transcription of rpmH suggests that the rnpA gene is the second gene in the rpmH operon.

Amino Acid Sequence↗
PubMed1985

Genetic characterization and partial sequence determination of a Treponema pallidum operon expressing two immunogenic membrane proteins in Escherichia coli.

A detailed physical and genetic map of a previously cloned 5.5-kilobase segment of Treponema pallidum DNA is described. This segment expressed two proteins that are cell membrane associated in Escherichia coli. The structural genes of these treponemal membrane proteins, tmpA and tmpB, are coordinately expressed, and transcription in E. coli can start from at least two different treponemal promoters. The tmpA and tmpB proteins are the products of in vivo proteolytic cleavage from precursor proteins which are 2 and 4 kilodaltons larger, respectively, than the mature proteins. Because the sizes of the corresponding proteins produced in T. pallidum were identical to those of the mature membrane proteins in E. coli, we concluded that a similar proteolytic processing takes place in both E. coli and T. pallidum. Although tmpA and tmpB were controlled by the same transcription signals, tmpB was expressed to a higher extent than tmpA, and only the tmpB product could be overproduced by placing the left lambda promoter in front of the structural genes. The nucleotide sequence of the T. pallidum tmpA gene was established. This is the first T. pallidum gene sequenced. Codon usage and the nature of transcriptional and translational signals are discussed. The deduced amino acid sequence indicated the presence of a sequence that was characteristic for a signal peptide. This sequence information allowed the construction of hybrid genes coding for proteins having beta-galactosidase enzyme activity as well as TmpA epitopes. The enzyme-linked antigen was expressed at a high level in E. coli when transcriptional and translational signals from coliphage lambda were used. In this case the protein produced was a sandwich protein consisting of 21 amino acids of the lambda cro protein, 204 amino acids of the T. pallidum TmpA protein, and 1,020 amino acids of the E. coli lambda-galactosidase. The potential use of this enzyme-linked antigen for the serodiagnosis of syphilis is discussed.

Amino Acid Sequence↗
PubMed1984

Fine structure genetic map and complementation analysis of mutations in the dnaA gene of Escherichia coli.

A fine structure genetic map of several mutations in the dnaA gene of Escherichia coli was constructed by the use of recombinant lambda and M13 phages. The dnaA508 mutation was found to be the mutation most proximal to the promoter, while the dnaA203 mutation was found to be the most distal one. The order of mutations established in this analysis was: dnaA508, dnaA167, (dnaA5, dnaA46, dnaA211), dnaA205, dnaA204, dnaA203. The mutations dnaA601, dnaA602, dnaA603, dnaA604 and dnaA606 were found to map very close to each other and close to dnaA205 in the middle third of the dnaA gene. In analysing the dominance relationship all 13 dnaA mutations were found to be recessive to the wild type. Characteristic phenotypes of the dnaA(Ts) mutants, like reversibility of the temperature inactivation of the dnaA protein, cold sensitivity of haploid or of merodiploid strains and suppressibility by rpoB mutations, are found to correlate with clusters of mutations within the gene.

Bacterial Proteins↗
PubMed1984

Determination of N-nitrosamines and N-nitrosamine precursors in rubber nipples from baby pacifiers by gas chromatography-thermal energy analysis.

N-Nitrosamines and precursors are present in rubber products in which the accelerators and stabilizers used in the vulcanization process were derived from dialkylamines. Research was performed to develop data concerning the presence of N-nitrosamines and precursors so that the health significance of the exposure problem related to infant ingestion of these chemicals could be properly assessed. Volatile N-nitrosamines were determined in cut-up pacifier nipples by extraction with dichloromethane followed by concentration in a Kuderna-Danish evaporator, high-temperature mineral oil purge and trap, and analysis by gas chromatography--thermal energy analysis (GC-TEA). N-nitrosodibutylamine (NDBA) was the principal N-nitrosamine found, with concentrations up to 427 ppb. N-Nitrosamines and precursors in cut-up and intact nipples were determined by GC-TEA after a single extraction with artificial saliva. NDBA was the principal nitrosamine found, at levels up to 1040 ppb, while dibutylamine (DBA) was the principal precursor found, at levels up to 3890 ppb. The persistence of these compounds in intact nipples was determined by multiple artificial saliva extractions. Amounts of NDBA and DBA found after 15 artificial saliva extractions of intact pacifier nipples totalled 824 ppb and 15.6 ppm, respectively. N-Nitrosamine levels generally showed a gradual decrease in concentration with each extraction, whereas no consistent trend could be determined for concentrations of precursors.

Bottle Feeding↗
PubMed1983

Anterior cervical discectomy with and without fusion. A prospective study.

A prospective randomized study to compare discectomy without (DE) and with fusion (DEF) included 63 patients operated on with DE returned to work during the first 9 weeks postoperatively than patients operated on with DEF (p less than 0.005 to 0.05). The prognosis is significantly better for men than for women after DEF (p less than 0.005), while no difference can be shown after DE.

Adult↗
PubMed1982

The nucleotide sequence of the dnaA gene and the first part of the dnaN gene of Escherichia coli K-12.

The nucleotide sequence of the dnaA gene and the first 10% of the dnaN gene was determined. From the nucleotide sequence the amino acid sequence of the dnaA gene product was derived. It is a basic protein of 467 amino acid residues with a molecular weight of 52.5 kD. The expression of the dnaA gene is in the counterclockwise direction like the one of the dnaN gene, for which potential startsites were found.

Amino Acid Sequence↗
PubMed1982

The nucleotide sequence of the dnaA gene promoter and of the adjacent rpmH gene, coding for the ribosomal protein L34, of Escherichia coli.

The nucleotide sequence was determined of a 945-bp EcoRI fragment from the Escherichia coli K-12 chromosome at 82 min containing the promoter region of the dnaA gene. This nucleotide sequence contained a coding sequence identical to the amino acid sequence of the ribosomal protein L34 , designated rpmH . The rimA mutation, which affects the maturation of 50S ribosomal particles, may be an allele of the rpmH gene since it maps close to, or within, the L34 coding sequence. The rpmH gene and the dnaA gene are transcribed in the clockwise and counter-clockwise direction, respectively. Nuclease S1 mapping of transcripts indicated the existence of two major promoters for the L34 gene and two promoters for the dnaA gene within the 945-bp EcoRI fragment.

Alleles↗
PubMed1978

Late meningeal effects of myelographic contrast media with special reference to metrizamide.

Two hundred and fifty-six myelograms in 192 patients were following by repeat myelography using a water-soluble contrast medium. The films of these re-examinations were analysed for signs of meningeal changes. Adhesive arachnoiditis had developed in five of 46 cases after methiodal sodium, in 24 of 96 cases after iothalamate meglumine, in seven of 12 cases after iocarmate meglumine, in seven of ten cases after iodophendylate, but in none of 90 cases after metrizamide. Dose of contrast medium, observation time and protein concentration of the CSF were found to be factors of importance for the development of adhesive arachnoiditis.

Adolescent↗
PubMed1976

A clinical trial of Amipaque in lumbar myelography.

Three hundred lumbar myelographies using a new water-soluble, non-electrolytic contrast medium, Amipaque, were assessed with reference to: 1) the correlation between radiological and operative diagnosis; 2) the side-effects during and after the myelography. Myelograms of the same reliability as those obtained with other water-soluble contrast media were obtained. However, arachnoiditis as sequelae to previous myelography with oil-soluble and earlier water-soluble contrast media prevented the correct evaluation in some cases. Spinal anaesthesia was not necessary. There was no case of muscle spasms or other serious complication. Eight patients who were re-examined with Amipaque more than two months later revealed no evidence of arachnoiditis as sequelae to the first Amipaque myelography.

Adult↗